Abbasali Yekta - Academia.edu (original) (raw)

Papers by Abbasali Yekta

Research paper thumbnail of Evaluation of the presence of a central fusion lock effect on fixation disparity curve parameters in symptomatic and asymptomatic subjects

Clinical and Experimental Optometry

ABSTRACT Clinical relevance: Several parameters are likely to affect the magnitude of fixation di... more ABSTRACT Clinical relevance: Several parameters are likely to affect the magnitude of fixation disparity (FD) and FD curve characteristics. Presence of a central fusion lock may have an important effect on clinical testing of FD and interpretation of its results. Background: The aim of this study was to evaluate FD curve parameters using the modified near Mallett unit (with a central fusion lock) and the Sheedy disparometer (without a central fusion lock) in symptomatic and asymptomatic subjects. Methods: This cross-sectional study was conducted in 147 patients with a mean age of 22.5 years who presented to the optometry clinic of Paramedical College of Mashhad University of Medical Sciences. The symptoms were recorded in a questionnaire for each patient. FD was measured using the modified near Mallett unit and Sheedy disparometer and FD curves were generated using the AutoCAD 2005 software. Results: There was a significant difference in the FD, associated phoria, and slope measurements between the two devices (all p values < 0.05). Significant difference was found in the mean FD between symptomatic and asymptomatic subjects using the modified near Mallett unit (p < 0.0001) and Sheey disparometer (p = 0.007). In symptomatic subjects, the mean slope was steeper for the modified near Mallett unit compared to the Sheedy disparometer (p = 0.001). Although the mean centre of symmetry was more negative in the modified near Mallett unit versus the Sheedy disparometer, the difference between the instruments was not significant in symptomatic (p = 0.477) and asymptomatic (p = 0.257) participants. Conclusion: There are differences in the FD curve parameters between the modified near Mallett unit and Sheedy disparometer. Slope is a proper criterion for differentiating asymptomatic subjects from symptomatic individuals. The modified near Mallett unit is a more precise tool for assessment of non-compensated heterophoria compared to the Sheedy disparometer.

Research paper thumbnail of Prevalence and associated factors of corneal arcus in the geriatric population; Tehran geriatric eye study

BMC Ophthalmology

Purpose To determine the age and sex-standardized prevalence of corneal arcus and its associated ... more Purpose To determine the age and sex-standardized prevalence of corneal arcus and its associated factors in a geriatric population. Methods This population-based cross-sectional study was conducted in 2019 in Tehran; the capital of Iran, using a multi-stage stratified random cluster sampling method. All participants underwent a detailed interview, blood pressure measurement, laboratory blood tests, and a complete ocular examination. Results Three thousand three hundred ten of 3791 invitees participated in the study (response rate: 87.31%). The mean age of the participants was 69.35 ± 7.62 years (60–97 years) and 1912 (57.76%) were female. Overall, the age and sex-standardized prevalence (95% CI) of corneal arcus was 44.28% (41.21–47.39). Based on the multiple logistic regression, the odds of corneal arcus were higher in men than in women (OR: 1.51; 95% CI: 1.14–2.00); in the age group ≥ 80 years compared to the age group 60–64 years (OR: 2.44; 95% CI: 1.68–3.53), and in retired peop...

Research paper thumbnail of Biomechanically-Corrected Intraocular Pressure Compared To Pressure Measured With Commonly Used Tonometers In Normal Subjects

Clinical Optometry, 2019

Purpose: To compare the biomechanically-corrected intraocular pressure (bIOP) measured by the Cor... more Purpose: To compare the biomechanically-corrected intraocular pressure (bIOP) measured by the Corvis ST (Oculus, Wetzlar, Germany) with IOP measurements made by other commonly used tonometers; and to test the correlations between IOP measures and central corneal thickness. Methods: One randomly-selected eye from each of 94 healthy subjects was assessed. The bIOP was determined by the CorVis ST and compared with the IOP measurements made by standard Goldmann Applanation Tonometer (GAT: Haag-Streit AG, Bern, Switzerland), the Icare (Icare Finland Oy, Vantaa, Finland), and the Ocular Response Analyzer (ORA-IOPcc: Reichert, New York, USA). Corneal thickness was assessed by the Oculus Pentacam. The correlation between bIOP and the other devices and between CCT were assessed using the Pearson correlation test or Spearman's rho test accordingly to the distribution of these values. The Bland-Altman method and intraclass correlation coefficients (ICC) were used to assess the agreement of bIOP results with IOP obtained with other techniques. The limits of agreement (LoA) were determined as the mean difference ±1.96 SD of the mean differences. In all tests, the significance level was considered to be 0.05. Results: Mean and SD of the bIOP were 16.11±1.66 mmHg. Significant differences were found between the bIOP and other IOP measurements (GAT, 3.02±2.60 mmHg, p<0.001, Icare, 1.51±2.95 mmHg, p<0.001, IOPcc, 1.09±1.96 mmHg, p<0.001). The lowest and highest mean differences in IOP were with the IOPcc and GAT, respectively. Interestingly, there were no significant differences in bIOP, GAT-IOP and ORA-IOPcc between the eyes with thin or thick corneal thicknesses, with Icare-IOP being the only exception (p<0.001). Conclusion: The Corvis bIOP has a higher correlation with the IOPcc by ORA, which are also compensated for the effects of corneal biomechanics and have less association with corneal thickness relative to the uncorrected GAT and Icare measurements.

Research paper thumbnail of Binocular Function in Different Gaze Positions

Journal of Ophthalmic and Vision Research

Purpose: To evaluate varied aspects of binocular function in multiple gaze positions. Methods: In... more Purpose: To evaluate varied aspects of binocular function in multiple gaze positions. Methods: In 2018, this cross-sectional study was conducted on 21 participants (male = 11) with an age range of 19–25 years. Having emmetropia and 10/10 visual acuity in both eyes were conditions of the inclusion criteria for the crosssectional study. The following aspects of binocular function including amplitude of accommodation (AA), near point of convergence, near phoria, and monocular accommodative facility were evaluated in five gazes (primary, upward, downward, left, and right) for all subjects. Results: Near point of convergence values showed significant differences in all gaze positions (P < 0.001). The lowest near point of convergence value was seen in the primary gaze (2.69 cm) and the downward gaze (3.47 cm) and the highest near point of convergence value was seen in the left gaze (7.5 cm). There was also a significant difference in the amplitude of accommodation among the upward, dow...

Research paper thumbnail of Corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure and their associated factors in the geriatric population, a population-based study

International Ophthalmology, 2022

To determine the distribution of corneal-compensated intraocular pressure (IOPcc), Goldmann-corre... more To determine the distribution of corneal-compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg) and their associated factors in a geriatric population. The present cross-sectional study was performed in individuals above 60 years of age in Tehran, the capital of Iran. The sampling was performed using multi-stage random cluster sampling method. All participants underwent preliminary ocular examinations, and then imaging by Pentacam HR and IOL master 500. Measurement of IOPg, IOPcc, and corneal biomechanical indices including corneal hysteresis (CH) and corneal resistant factor (CRF) was performed in a random sub-sample using ocular response analyzer (ORA). The mean IOPg and IOPcc were 16.76 ± 4.71 mmHg and 19.05 ± 4.67 mmHg, respectively. There were no statistically significant differences in both IOPg (p = 0.891) and IOPcc (p = 0.248) between males and females. Based on the multiple linear regression models, both IOPg and IOPcc showed a statistically significant direct relationship with CRF (P < 0.001) and a significant inverse relationship with CH (P < 0.001 for IOPg and IOPcc), anterior chamber angle (ACA) (p = 0.006 for IOPg and p = 0.017 for IOPcc), and spherical equivalent refractive error (p = 0.032 for IOPg and p = 0.046 for IOPcc). Mean IOPg and IOPcc in the present study were higher compared to most previous studies. Corneal biomechanical indices including CH and CRF, refractive error and anterior chamber angle were independent associated factors of IOPg and IOPcc in the present study. There was no significant relationship between ORA-derived IOP values and CCT.

Research paper thumbnail of Demographic profile, clinical, and topographic characteristics of keratoconus patients attending at a tertiary eye center

Journal of Current Ophthalmology, 2019

To evaluate the demographic profile, clinical, and topographic characteristics of keratoconus (KC... more To evaluate the demographic profile, clinical, and topographic characteristics of keratoconus (KCN) patients attending at a subspecialty eye hospital in Tehran, Iran. Methods: In this cross-sectional study, all patients who attended Noor Eye Hospital between March 2011 and March 2017 and had a diagnosis of KCN were identified, and the required number of patients was randomly selected. The following data were extracted from patient's records: age, sex, visual acuity, refraction, keratometry, pachymetry, and treatment procedures. The data of KCN laterality, severity, morphology, and cone location were also extracted by analyzing the corneal imaging maps. Results: The records of 1080 eyes of 540 patients were evaluated. The mean age of the participants was 31.04 ± 8.54 years (range, 13e63 years), and 69.3% of the patients were male. The highest and lowest frequency of KCN was seen in the age group 20e30 years and above 50 years, respectively. Bilateral KCN was detected in 93.3% [95% confidence interval (CI): 91.68e94.75] of the subjects. 43.7% (95%CI: 32.88e54.48), 55.6% (95%CI: 44.73e66.38), and 0.8% (95%CI: 0.75e0.78) of the cases had nipple, oval, and globus cones, respectively. The cone was central in 52.1% (95%CI: 41.10e63.11), paracentral in 43.6% (95%CI: 36.13e51.04), and peripheral in 4.3% (95%CI: 00.76e7.86) of the cases. The frequency percentage of KCN according to severity was 15.2% (95%CI: 13.09e17.46), 56.4% (95%CI: 53.37e59.37), and 28.4% (95%CI: 25.75e31.21) for mild, moderate, and severe KCN, respectively. Among different parameters, only cone location had a significant association with age as the frequency of paracentral and peripheral cones increased with ageing (P ¼ 0.002). Conclusions: The mean age of KCN patients in our study was higher than similar studies in other Asian countries. KCN was bilateral in most cases with an oval morphology and central cone location. Most of the patients had moderate to severe KCN.

Research paper thumbnail of Global and regional estimates of the prevalence of root caries – Systematic review and meta-analysis

The Saudi Dental Journal, 2018

Aim: To evaluate the pooled prevalence of root caries through a systematic review and meta-analys... more Aim: To evaluate the pooled prevalence of root caries through a systematic review and meta-analysis. Methods: A keyword search was done in Scopus, Pubmed and CINAHL databases using all the synonyms of root caries in the published literature (till January 1st, 2018). The search was supplemented with standard Boolean operators and other keywords like prevalence, epidemiology in the title, abstract and MeSH terms. Data was extracted and exported to Covidence software for screening and removal of duplicates. Results: The search revealed a total of 492 documents from Scopus (n = 95), Pubmed (n = 220) and CINAHL (n = 177). Random effects model was used as there was a high degree of heterogeneity was seen among the studies published (I 2 = 99.62%). A total of 74 publications were included in the analysis of the pooled prevalence of root caries which yielded a prevalence of 41.5 (36.9-46.1). Conclusion: Root caries is a significant problem, and four out of ten adults might be affected.

Research paper thumbnail of Are the results of handheld auto-refractometer as valid as the result of table-mounted refractometer?

Journal of Current Ophthalmology, 2018

Purpose: To determine the agreement of table-mounted and handheld auto-refractometers and to eval... more Purpose: To determine the agreement of table-mounted and handheld auto-refractometers and to evaluate the effect of age and different types of refractive errors on this comparison. Methods: In this cross-sectional study conducted in 2015 using multi-stage cluster sampling, two underserved villages were selected randomly in the north and southwest of Iran. All the selected participants underwent optometric and ophthalmic examinations. Refraction was measured using handheld and table-mounted auto-refractometers in 652 subjects. Results: The mean age of the subjects was 32.7 ± 18.72 years, and 58.3% of them were female. A significant difference was observed in the results of sphere, spherical equivalent (SE), and J45 vector between the two devices (P < 0.012), but there was no significant difference in J0 vector. There was a significant difference in the results of sphere between the two devices in all age groups under 50 years (P ¼ 0.005), but there was no difference in age groups above 50 years. Correlation coefficients of the two devices were 0.989, 0.986, 0.908, and 0.951 for the results of sphere, SE, J0 vector, and J45 vector, respectively (P < 0.0001). The 95% limit of agreement (LOA) of the two devices was À0.31 to þ0.53 for sphere, À0.27 to þ0.63 for SE, À0.27 to þ0.27 for J0 vector, and À0.16 to À0.17 for J45 vector. Conclusions: According to our findings, the spherical error and cylindrical power measurements of the two devices have a significant correlation. Although there is a significant difference in the mean values between the two devices, this difference may be considered clinically insignificant, and considering the narrow 95% LOA between the two devices, the results may be used interchangeably.

Research paper thumbnail of The prevalence of refractive errors among adult rural populations in Iran

Clinical and Experimental Optometry, 2017

In this cross-sectional study, we used cluster sampling for selecting participants from every dep... more In this cross-sectional study, we used cluster sampling for selecting participants from every department of Mashhad University of Medical Sciences, proportional to the number of students in each department. Each participant received refraction examination with an autorefractometer and check up with a retinoscope. Myopia and hyperopia were defined as spherical equivalent (SE) less than-0.5 and more than +0.5 D, respectively. Astigmatism was defined as cylinder power worse than 0.5 D. Results: Out of 1,745 selected individuals, the data of 1,431 participants were analyzed after implementing the exclusion criteria; 58.8% of the participants were female and the mean age of the participants was 23.8±3.8 years (range, 18-32 years). Myopia, hyperopia, and astigmatism were seen in 41.7% (95%CI 38.7-44.7), 7.8% (95%CI 6.2-9.4), and 25.6% (95%CI 23-28.3) of the students in this study, respectively. The prevalence of myopia increased significantly with age (OR=1.16 1.12-1.20 p<0.001). The prevalence of hyperopia was significantly higher in females (OR=2.1 1.1-3.7 p=0.025) and decreased significantly with age (OR=0.87 0.81-0.94 p=0.001). The prevalence of astigmatism increased significantly with age. Moreover, 6% of the students had anisometropia and 1.2% had high myopia. Conclusion: The prevalence of myopia was considerably high in these students; therefore, attention to this age group to identify and correct the refractive errors should receive priority in the health system.

Research paper thumbnail of The prevalence of asthenopia and its determinants in a population of university students

Acta Ophthalmologica, 2017

Research paper thumbnail of Paper: THE PREVALENCE OF VISUAL PROBLEMS IN SCHOOL CHILDREN, SHIRAZ, IRAN

Research paper thumbnail of Age-Related Changes in Type and Amount of Refractive Errors

Optometry and Vision Science, 2001

Research paper thumbnail of Refractive errors before and after presbyopia

THE JOURNAL OF …, 2005

Methods: This was a cross sectional study carried out at the department of optometry (Mashhad Uni... more Methods: This was a cross sectional study carried out at the department of optometry (Mashhad University of Medical Sciences) in 2001. Following routine optometric examination, the type and degree of refractive errors of 500 patients before and after presbyopia were statically ...

Research paper thumbnail of The normal distribution of corneal eccentricity and its determinants in two rural areas of north and south of Iran

Journal of Current Ophthalmology, 2018

Research paper thumbnail of Four-year change in ocular biometric components and refraction in schoolchildren: A cohort study

Journal of Current Ophthalmology, 2018

Purpose: To determine 4-year changes of ocular biometric and dioptric components in Iranian child... more Purpose: To determine 4-year changes of ocular biometric and dioptric components in Iranian children aged 7e11 years following the first phase. Methods: 468 children were evaluated in the first phase of the study in 2012 and again in 2016e2017. Multi-stage stratified cluster sampling was applied to select the participants. The Topcon autorefractometer and the LENSTAR/BioGraph biometer (WaveLight AG, Erlangen, Germany) were used for cycloplegic refraction and biometry, respectively. All measurements were repeated at 4 years as the baseline assessments. Results: Of 468 children, 251 (53.6%) were boys. Spherical equivalent (SE) showed a marked myopic shift (P ¼ 0.000) in the second phase which was significantly higher in boys (0.24 vs. 0.18 D) (P < 0.001). Axial length (AL) and anterior chamber depth (ACD) increased by 0.49 ± 0.05 and 0.12 ± 0.02 mm, while lens thickness (LT) and lens power (LP) decreased by 0.08 ± 0.01 mm and 1.59 ± 0.12 D, respectively (P < 0.05). The mean corneal curvature and thickness did not change significantly during 4 years. All biometric component changes were greater in boys. Biometric changes in different age groups showed a decreased LP, increased AL, and increased ACD in most age groups (P < 0.05), while LT and SE did not change significantly in the age groups 9 and 11 years and 8 and 9 years, respectively. Changes in the corneal thickness, diameter, curvature, and refractive astigmatism were not significant in any of the age groups (P > 0.05). Conclusions: Statistical and clinical changes were seen in AL, ACD, LP, and LT. The changes observed in biometric components (AL, ACD, and LT) had a sinus rhythm.

Research paper thumbnail of The Effect of Cyclopentolate on Ocular Biometric Components

Optometry and Vision Science, 2020

SIGNIFICANCE It is apparent that a variety of biometric changes are caused by different types of ... more SIGNIFICANCE It is apparent that a variety of biometric changes are caused by different types of cycloplegic eye drops. However, these effects are inconsistent and have not been reported in different refractive groups. PURPOSE The purpose of this study was to determine the effect of cyclopentolate 1% on ocular biometric components in different types of refractive errors in children. METHODS This cross-sectional study was conducted on 226 eyes of 113 schoolchildren in Shahroud, northeast Iran, with a mean ± standard deviation age of 9.20 ± 1.65 years. All participants had noncycloplegic and cycloplegic objective refraction using an autorefractometer. Cycloplegia was induced using cyclopentolate 1% eye drops. Biometric measurements were made with Allegro Biograph (WaveLight AG, Erlangen, Germany) before and after administering cycloplegic drops. Mixed-effect model regression was used to analyze the data. RESULTS After cycloplegia, the vitreous chamber depth (VCD) (−0.043; 95% confidence interval [CI], −0.067 to −0.019 mm), lens thickness (−0.146; 95% CI, −0.175 to −0.117 mm), axial length (−0.009; 95% CI, −0.012 to −0.006 mm), and lens power (−0.335; 95% CI, −0.463 to −0.208 D) decreased significantly, whereas the anterior chamber depth (ACD) (0.183; 95% CI, 0.164 to 0.202 mm), anterior segment length (0.036; 95% CI, 0.014 to 0.058) mm), lens central point (0.109; 95% CI, 0.094 to 0.124 mm), and pupil diameter (1.599; 95% CI, 1.482 to 1.716 mm) increased (P value for all tests, <.001). For changes in VCD and ACD, a significant interaction was observed between different types of refractive errors and cycloplegia, such that the adjusted mean change for ACD was significantly lower and for VCD was significantly higher in hyperopes compared with emmetropes. Lens center moves backward in myopes (0.17 mm) and stays the same in hyperopes under cycloplegia. CONCLUSIONS According to the findings of this study, cycloplegia reduces the thickness of the crystalline lens and subsequently causes an increase in the ACD. Cycloplegia-related ocular biometric changes were different by type of refractive error.

Research paper thumbnail of Relation Between Near Work and Ocular Biometric Components

International journal of occupational hygiene, 2015

ORIGINAL ARTICLE To determine the association between ocular biometric components and near work i... more ORIGINAL ARTICLE To determine the association between ocular biometric components and near work in bank employees.This study was conducted as an analytical cross-sectional study. A group of bank employees and a control group were randomly selected. After applying the inclusion criteria, all selected subjects had a set of examinations including refraction, uncorrected and corrected visual acuity, slit lamp biomicroscopy and ophthalmoscopy. Then ocular biometric indices were measured using a Nidek biometer (US 800).Mean spherical equivalent was -0.53 (95%CI: -0.7 to -0.36) diopter (D) in bank employees and 0.09(95%CI: -0.05 to 0.23) D in the control group(p<0.001). After adjusting for age and gender, axial length and vitreous chamber depth were significantly longer in bank employees. In a logistic regression model, near work significantly correlated with increasing axial length 1.89(95%CI: 1.3 to 2.75) and decreasing corneal radius of curvature 0.22 (95%CI: 0.08 to 0.63) after adju...

Research paper thumbnail of Effect of Occlusion Therapy on Visual Acuity, Contrast Sensitivity and Stereopsis in Amblyopia

Purpose: To determine the effect of occluding a normal eye on visual acuity, contrast sensitivity... more Purpose: To determine the effect of occluding a normal eye on visual acuity, contrast sensitivity and stereopsis in amblyopic school children. Methods: Amblyopic children from primary schools of region 2 in Mashhad were identified and referred to Optometry Clinics of Mashhad Medical University through a screening program. Informed consent was obtained from the parents. All subjects underwent an ophthalmologic examination including visual acuity, subjective refractive error, biomicroscopy and funduscopy. Best-corrected visual acuity (BCVA), contrast sensitivity and stereopsis were measured by Snellen E chart, Cambridge low contrast chart and Titmus stereotest , respectively. All tests were repeated 2 weeks, 1 month and 3 months after initial examination. Results: Of 1,947 children, 289 (14.8%) were amblyopic of whom 62 subjects were eventually enrolled for the study. BCVA in the amblyopic eye was less than 3/10 in 25.8% of subjects before treatment however all children had BCVA of 3/...

Research paper thumbnail of The prevalence of Amblyopia in a young Population

British Journal of Visual Impairment

Purpose: The aim of this study was to determine the prevalence of amblyopia and its determinants ... more Purpose: The aim of this study was to determine the prevalence of amblyopia and its determinants in Iranian students above 18 years. Methods: In this university-based cross-sectional study, multi-stage cluster sampling was used to select participants. After selecting the students, visual acuity, objective, and subjective refraction were measured and the best-corrected visual acuity was determined. Results: We evaluated 1462 individuals with a mean age of 22.8 ± 3.1 years in this study, of whom 73% were female. The prevalence of amblyopia was 2.19% (95% confidence interval [CI]: [1.43, 2.93]), of which 6.2% was strabismic, 71.8% was refractive (isometropic and anisometropic), and 22.0% was mix (strabismic and anisometropic). No difference was observed in the prevalence of amblyopia between boys and girls (p value = 0.315). The prevalence of amblyopia was 3.93%, 1.71%, 3.79%, and 0% in the age group 18–20, 21–25, 26–30, and above 30 years, respectively (p value = 0.071). Conclusion: The results of this study, as the first study investigating the prevalence of amblyopia in Iranian adults, showed a rather higher prevalence of amblyopia in Iranian university students compared to other studies on adults in other countries. Moreover, similar to some other studies, refractive amblyopia had a higher prevalence than other types.

Research paper thumbnail of Tear film secretion and stability in welders

Contact Lens and Anterior Eye

PURPOSE Welders are prone to ocular injuries and ocular surface problems due to exposure to ultra... more PURPOSE Welders are prone to ocular injuries and ocular surface problems due to exposure to ultraviolet light. The aim of this study was to evaluate the tear film comprehensively and assess objective and subjective indices of dry eye in welders. METHODS In this historical cohort, welders with at least 5 years of experience were compared with controls. A complete evaluation of ocular health was done for all participants. The Schirmer test (invasive and non-invasive) and Invasive Tear Break-Up Time (ITBUT) were applied for objective evaluation and the Ocular Surface Disease Index (OSDI) was used for subjective assessment of the tear film status. The results were compared between the two groups using the SPSS software. RESULTS The results of 140 welders (mean age: 46.66 ± 13.01 years) and 172 controls (mean age: 45.05 ± 12.61) were analyzed. The values of the Schirmer test and ITBUT were significantly lower in welders than controls; the difference was more prominent for the Schirmer test as compared to TBUT (Schirmer difference = 4.98 mm, ITBUT difference = 2.23 s). OSDI values were also significantly lower in welders than controls (P < 0.001). Considering a cut-off point of 12, 81.2% of welders had degrees of dry eye which was severe in 46.2% while 35.5% of controls had dry eye. CONCLUSION The results indicate that the percentage of dry eye and tear problems is far higher in welders than non-welders. Most of the affected welders have severe dry eye. It seems that the main reason for dry eye in these people is aqueous deficiency.

Research paper thumbnail of Evaluation of the presence of a central fusion lock effect on fixation disparity curve parameters in symptomatic and asymptomatic subjects

Clinical and Experimental Optometry

ABSTRACT Clinical relevance: Several parameters are likely to affect the magnitude of fixation di... more ABSTRACT Clinical relevance: Several parameters are likely to affect the magnitude of fixation disparity (FD) and FD curve characteristics. Presence of a central fusion lock may have an important effect on clinical testing of FD and interpretation of its results. Background: The aim of this study was to evaluate FD curve parameters using the modified near Mallett unit (with a central fusion lock) and the Sheedy disparometer (without a central fusion lock) in symptomatic and asymptomatic subjects. Methods: This cross-sectional study was conducted in 147 patients with a mean age of 22.5 years who presented to the optometry clinic of Paramedical College of Mashhad University of Medical Sciences. The symptoms were recorded in a questionnaire for each patient. FD was measured using the modified near Mallett unit and Sheedy disparometer and FD curves were generated using the AutoCAD 2005 software. Results: There was a significant difference in the FD, associated phoria, and slope measurements between the two devices (all p values < 0.05). Significant difference was found in the mean FD between symptomatic and asymptomatic subjects using the modified near Mallett unit (p < 0.0001) and Sheey disparometer (p = 0.007). In symptomatic subjects, the mean slope was steeper for the modified near Mallett unit compared to the Sheedy disparometer (p = 0.001). Although the mean centre of symmetry was more negative in the modified near Mallett unit versus the Sheedy disparometer, the difference between the instruments was not significant in symptomatic (p = 0.477) and asymptomatic (p = 0.257) participants. Conclusion: There are differences in the FD curve parameters between the modified near Mallett unit and Sheedy disparometer. Slope is a proper criterion for differentiating asymptomatic subjects from symptomatic individuals. The modified near Mallett unit is a more precise tool for assessment of non-compensated heterophoria compared to the Sheedy disparometer.

Research paper thumbnail of Prevalence and associated factors of corneal arcus in the geriatric population; Tehran geriatric eye study

BMC Ophthalmology

Purpose To determine the age and sex-standardized prevalence of corneal arcus and its associated ... more Purpose To determine the age and sex-standardized prevalence of corneal arcus and its associated factors in a geriatric population. Methods This population-based cross-sectional study was conducted in 2019 in Tehran; the capital of Iran, using a multi-stage stratified random cluster sampling method. All participants underwent a detailed interview, blood pressure measurement, laboratory blood tests, and a complete ocular examination. Results Three thousand three hundred ten of 3791 invitees participated in the study (response rate: 87.31%). The mean age of the participants was 69.35 ± 7.62 years (60–97 years) and 1912 (57.76%) were female. Overall, the age and sex-standardized prevalence (95% CI) of corneal arcus was 44.28% (41.21–47.39). Based on the multiple logistic regression, the odds of corneal arcus were higher in men than in women (OR: 1.51; 95% CI: 1.14–2.00); in the age group ≥ 80 years compared to the age group 60–64 years (OR: 2.44; 95% CI: 1.68–3.53), and in retired peop...

Research paper thumbnail of Biomechanically-Corrected Intraocular Pressure Compared To Pressure Measured With Commonly Used Tonometers In Normal Subjects

Clinical Optometry, 2019

Purpose: To compare the biomechanically-corrected intraocular pressure (bIOP) measured by the Cor... more Purpose: To compare the biomechanically-corrected intraocular pressure (bIOP) measured by the Corvis ST (Oculus, Wetzlar, Germany) with IOP measurements made by other commonly used tonometers; and to test the correlations between IOP measures and central corneal thickness. Methods: One randomly-selected eye from each of 94 healthy subjects was assessed. The bIOP was determined by the CorVis ST and compared with the IOP measurements made by standard Goldmann Applanation Tonometer (GAT: Haag-Streit AG, Bern, Switzerland), the Icare (Icare Finland Oy, Vantaa, Finland), and the Ocular Response Analyzer (ORA-IOPcc: Reichert, New York, USA). Corneal thickness was assessed by the Oculus Pentacam. The correlation between bIOP and the other devices and between CCT were assessed using the Pearson correlation test or Spearman's rho test accordingly to the distribution of these values. The Bland-Altman method and intraclass correlation coefficients (ICC) were used to assess the agreement of bIOP results with IOP obtained with other techniques. The limits of agreement (LoA) were determined as the mean difference ±1.96 SD of the mean differences. In all tests, the significance level was considered to be 0.05. Results: Mean and SD of the bIOP were 16.11±1.66 mmHg. Significant differences were found between the bIOP and other IOP measurements (GAT, 3.02±2.60 mmHg, p<0.001, Icare, 1.51±2.95 mmHg, p<0.001, IOPcc, 1.09±1.96 mmHg, p<0.001). The lowest and highest mean differences in IOP were with the IOPcc and GAT, respectively. Interestingly, there were no significant differences in bIOP, GAT-IOP and ORA-IOPcc between the eyes with thin or thick corneal thicknesses, with Icare-IOP being the only exception (p<0.001). Conclusion: The Corvis bIOP has a higher correlation with the IOPcc by ORA, which are also compensated for the effects of corneal biomechanics and have less association with corneal thickness relative to the uncorrected GAT and Icare measurements.

Research paper thumbnail of Binocular Function in Different Gaze Positions

Journal of Ophthalmic and Vision Research

Purpose: To evaluate varied aspects of binocular function in multiple gaze positions. Methods: In... more Purpose: To evaluate varied aspects of binocular function in multiple gaze positions. Methods: In 2018, this cross-sectional study was conducted on 21 participants (male = 11) with an age range of 19–25 years. Having emmetropia and 10/10 visual acuity in both eyes were conditions of the inclusion criteria for the crosssectional study. The following aspects of binocular function including amplitude of accommodation (AA), near point of convergence, near phoria, and monocular accommodative facility were evaluated in five gazes (primary, upward, downward, left, and right) for all subjects. Results: Near point of convergence values showed significant differences in all gaze positions (P < 0.001). The lowest near point of convergence value was seen in the primary gaze (2.69 cm) and the downward gaze (3.47 cm) and the highest near point of convergence value was seen in the left gaze (7.5 cm). There was also a significant difference in the amplitude of accommodation among the upward, dow...

Research paper thumbnail of Corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure and their associated factors in the geriatric population, a population-based study

International Ophthalmology, 2022

To determine the distribution of corneal-compensated intraocular pressure (IOPcc), Goldmann-corre... more To determine the distribution of corneal-compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg) and their associated factors in a geriatric population. The present cross-sectional study was performed in individuals above 60 years of age in Tehran, the capital of Iran. The sampling was performed using multi-stage random cluster sampling method. All participants underwent preliminary ocular examinations, and then imaging by Pentacam HR and IOL master 500. Measurement of IOPg, IOPcc, and corneal biomechanical indices including corneal hysteresis (CH) and corneal resistant factor (CRF) was performed in a random sub-sample using ocular response analyzer (ORA). The mean IOPg and IOPcc were 16.76 ± 4.71 mmHg and 19.05 ± 4.67 mmHg, respectively. There were no statistically significant differences in both IOPg (p = 0.891) and IOPcc (p = 0.248) between males and females. Based on the multiple linear regression models, both IOPg and IOPcc showed a statistically significant direct relationship with CRF (P < 0.001) and a significant inverse relationship with CH (P < 0.001 for IOPg and IOPcc), anterior chamber angle (ACA) (p = 0.006 for IOPg and p = 0.017 for IOPcc), and spherical equivalent refractive error (p = 0.032 for IOPg and p = 0.046 for IOPcc). Mean IOPg and IOPcc in the present study were higher compared to most previous studies. Corneal biomechanical indices including CH and CRF, refractive error and anterior chamber angle were independent associated factors of IOPg and IOPcc in the present study. There was no significant relationship between ORA-derived IOP values and CCT.

Research paper thumbnail of Demographic profile, clinical, and topographic characteristics of keratoconus patients attending at a tertiary eye center

Journal of Current Ophthalmology, 2019

To evaluate the demographic profile, clinical, and topographic characteristics of keratoconus (KC... more To evaluate the demographic profile, clinical, and topographic characteristics of keratoconus (KCN) patients attending at a subspecialty eye hospital in Tehran, Iran. Methods: In this cross-sectional study, all patients who attended Noor Eye Hospital between March 2011 and March 2017 and had a diagnosis of KCN were identified, and the required number of patients was randomly selected. The following data were extracted from patient's records: age, sex, visual acuity, refraction, keratometry, pachymetry, and treatment procedures. The data of KCN laterality, severity, morphology, and cone location were also extracted by analyzing the corneal imaging maps. Results: The records of 1080 eyes of 540 patients were evaluated. The mean age of the participants was 31.04 ± 8.54 years (range, 13e63 years), and 69.3% of the patients were male. The highest and lowest frequency of KCN was seen in the age group 20e30 years and above 50 years, respectively. Bilateral KCN was detected in 93.3% [95% confidence interval (CI): 91.68e94.75] of the subjects. 43.7% (95%CI: 32.88e54.48), 55.6% (95%CI: 44.73e66.38), and 0.8% (95%CI: 0.75e0.78) of the cases had nipple, oval, and globus cones, respectively. The cone was central in 52.1% (95%CI: 41.10e63.11), paracentral in 43.6% (95%CI: 36.13e51.04), and peripheral in 4.3% (95%CI: 00.76e7.86) of the cases. The frequency percentage of KCN according to severity was 15.2% (95%CI: 13.09e17.46), 56.4% (95%CI: 53.37e59.37), and 28.4% (95%CI: 25.75e31.21) for mild, moderate, and severe KCN, respectively. Among different parameters, only cone location had a significant association with age as the frequency of paracentral and peripheral cones increased with ageing (P ¼ 0.002). Conclusions: The mean age of KCN patients in our study was higher than similar studies in other Asian countries. KCN was bilateral in most cases with an oval morphology and central cone location. Most of the patients had moderate to severe KCN.

Research paper thumbnail of Global and regional estimates of the prevalence of root caries – Systematic review and meta-analysis

The Saudi Dental Journal, 2018

Aim: To evaluate the pooled prevalence of root caries through a systematic review and meta-analys... more Aim: To evaluate the pooled prevalence of root caries through a systematic review and meta-analysis. Methods: A keyword search was done in Scopus, Pubmed and CINAHL databases using all the synonyms of root caries in the published literature (till January 1st, 2018). The search was supplemented with standard Boolean operators and other keywords like prevalence, epidemiology in the title, abstract and MeSH terms. Data was extracted and exported to Covidence software for screening and removal of duplicates. Results: The search revealed a total of 492 documents from Scopus (n = 95), Pubmed (n = 220) and CINAHL (n = 177). Random effects model was used as there was a high degree of heterogeneity was seen among the studies published (I 2 = 99.62%). A total of 74 publications were included in the analysis of the pooled prevalence of root caries which yielded a prevalence of 41.5 (36.9-46.1). Conclusion: Root caries is a significant problem, and four out of ten adults might be affected.

Research paper thumbnail of Are the results of handheld auto-refractometer as valid as the result of table-mounted refractometer?

Journal of Current Ophthalmology, 2018

Purpose: To determine the agreement of table-mounted and handheld auto-refractometers and to eval... more Purpose: To determine the agreement of table-mounted and handheld auto-refractometers and to evaluate the effect of age and different types of refractive errors on this comparison. Methods: In this cross-sectional study conducted in 2015 using multi-stage cluster sampling, two underserved villages were selected randomly in the north and southwest of Iran. All the selected participants underwent optometric and ophthalmic examinations. Refraction was measured using handheld and table-mounted auto-refractometers in 652 subjects. Results: The mean age of the subjects was 32.7 ± 18.72 years, and 58.3% of them were female. A significant difference was observed in the results of sphere, spherical equivalent (SE), and J45 vector between the two devices (P < 0.012), but there was no significant difference in J0 vector. There was a significant difference in the results of sphere between the two devices in all age groups under 50 years (P ¼ 0.005), but there was no difference in age groups above 50 years. Correlation coefficients of the two devices were 0.989, 0.986, 0.908, and 0.951 for the results of sphere, SE, J0 vector, and J45 vector, respectively (P < 0.0001). The 95% limit of agreement (LOA) of the two devices was À0.31 to þ0.53 for sphere, À0.27 to þ0.63 for SE, À0.27 to þ0.27 for J0 vector, and À0.16 to À0.17 for J45 vector. Conclusions: According to our findings, the spherical error and cylindrical power measurements of the two devices have a significant correlation. Although there is a significant difference in the mean values between the two devices, this difference may be considered clinically insignificant, and considering the narrow 95% LOA between the two devices, the results may be used interchangeably.

Research paper thumbnail of The prevalence of refractive errors among adult rural populations in Iran

Clinical and Experimental Optometry, 2017

In this cross-sectional study, we used cluster sampling for selecting participants from every dep... more In this cross-sectional study, we used cluster sampling for selecting participants from every department of Mashhad University of Medical Sciences, proportional to the number of students in each department. Each participant received refraction examination with an autorefractometer and check up with a retinoscope. Myopia and hyperopia were defined as spherical equivalent (SE) less than-0.5 and more than +0.5 D, respectively. Astigmatism was defined as cylinder power worse than 0.5 D. Results: Out of 1,745 selected individuals, the data of 1,431 participants were analyzed after implementing the exclusion criteria; 58.8% of the participants were female and the mean age of the participants was 23.8±3.8 years (range, 18-32 years). Myopia, hyperopia, and astigmatism were seen in 41.7% (95%CI 38.7-44.7), 7.8% (95%CI 6.2-9.4), and 25.6% (95%CI 23-28.3) of the students in this study, respectively. The prevalence of myopia increased significantly with age (OR=1.16 1.12-1.20 p<0.001). The prevalence of hyperopia was significantly higher in females (OR=2.1 1.1-3.7 p=0.025) and decreased significantly with age (OR=0.87 0.81-0.94 p=0.001). The prevalence of astigmatism increased significantly with age. Moreover, 6% of the students had anisometropia and 1.2% had high myopia. Conclusion: The prevalence of myopia was considerably high in these students; therefore, attention to this age group to identify and correct the refractive errors should receive priority in the health system.

Research paper thumbnail of The prevalence of asthenopia and its determinants in a population of university students

Acta Ophthalmologica, 2017

Research paper thumbnail of Paper: THE PREVALENCE OF VISUAL PROBLEMS IN SCHOOL CHILDREN, SHIRAZ, IRAN

Research paper thumbnail of Age-Related Changes in Type and Amount of Refractive Errors

Optometry and Vision Science, 2001

Research paper thumbnail of Refractive errors before and after presbyopia

THE JOURNAL OF …, 2005

Methods: This was a cross sectional study carried out at the department of optometry (Mashhad Uni... more Methods: This was a cross sectional study carried out at the department of optometry (Mashhad University of Medical Sciences) in 2001. Following routine optometric examination, the type and degree of refractive errors of 500 patients before and after presbyopia were statically ...

Research paper thumbnail of The normal distribution of corneal eccentricity and its determinants in two rural areas of north and south of Iran

Journal of Current Ophthalmology, 2018

Research paper thumbnail of Four-year change in ocular biometric components and refraction in schoolchildren: A cohort study

Journal of Current Ophthalmology, 2018

Purpose: To determine 4-year changes of ocular biometric and dioptric components in Iranian child... more Purpose: To determine 4-year changes of ocular biometric and dioptric components in Iranian children aged 7e11 years following the first phase. Methods: 468 children were evaluated in the first phase of the study in 2012 and again in 2016e2017. Multi-stage stratified cluster sampling was applied to select the participants. The Topcon autorefractometer and the LENSTAR/BioGraph biometer (WaveLight AG, Erlangen, Germany) were used for cycloplegic refraction and biometry, respectively. All measurements were repeated at 4 years as the baseline assessments. Results: Of 468 children, 251 (53.6%) were boys. Spherical equivalent (SE) showed a marked myopic shift (P ¼ 0.000) in the second phase which was significantly higher in boys (0.24 vs. 0.18 D) (P < 0.001). Axial length (AL) and anterior chamber depth (ACD) increased by 0.49 ± 0.05 and 0.12 ± 0.02 mm, while lens thickness (LT) and lens power (LP) decreased by 0.08 ± 0.01 mm and 1.59 ± 0.12 D, respectively (P < 0.05). The mean corneal curvature and thickness did not change significantly during 4 years. All biometric component changes were greater in boys. Biometric changes in different age groups showed a decreased LP, increased AL, and increased ACD in most age groups (P < 0.05), while LT and SE did not change significantly in the age groups 9 and 11 years and 8 and 9 years, respectively. Changes in the corneal thickness, diameter, curvature, and refractive astigmatism were not significant in any of the age groups (P > 0.05). Conclusions: Statistical and clinical changes were seen in AL, ACD, LP, and LT. The changes observed in biometric components (AL, ACD, and LT) had a sinus rhythm.

Research paper thumbnail of The Effect of Cyclopentolate on Ocular Biometric Components

Optometry and Vision Science, 2020

SIGNIFICANCE It is apparent that a variety of biometric changes are caused by different types of ... more SIGNIFICANCE It is apparent that a variety of biometric changes are caused by different types of cycloplegic eye drops. However, these effects are inconsistent and have not been reported in different refractive groups. PURPOSE The purpose of this study was to determine the effect of cyclopentolate 1% on ocular biometric components in different types of refractive errors in children. METHODS This cross-sectional study was conducted on 226 eyes of 113 schoolchildren in Shahroud, northeast Iran, with a mean ± standard deviation age of 9.20 ± 1.65 years. All participants had noncycloplegic and cycloplegic objective refraction using an autorefractometer. Cycloplegia was induced using cyclopentolate 1% eye drops. Biometric measurements were made with Allegro Biograph (WaveLight AG, Erlangen, Germany) before and after administering cycloplegic drops. Mixed-effect model regression was used to analyze the data. RESULTS After cycloplegia, the vitreous chamber depth (VCD) (−0.043; 95% confidence interval [CI], −0.067 to −0.019 mm), lens thickness (−0.146; 95% CI, −0.175 to −0.117 mm), axial length (−0.009; 95% CI, −0.012 to −0.006 mm), and lens power (−0.335; 95% CI, −0.463 to −0.208 D) decreased significantly, whereas the anterior chamber depth (ACD) (0.183; 95% CI, 0.164 to 0.202 mm), anterior segment length (0.036; 95% CI, 0.014 to 0.058) mm), lens central point (0.109; 95% CI, 0.094 to 0.124 mm), and pupil diameter (1.599; 95% CI, 1.482 to 1.716 mm) increased (P value for all tests, <.001). For changes in VCD and ACD, a significant interaction was observed between different types of refractive errors and cycloplegia, such that the adjusted mean change for ACD was significantly lower and for VCD was significantly higher in hyperopes compared with emmetropes. Lens center moves backward in myopes (0.17 mm) and stays the same in hyperopes under cycloplegia. CONCLUSIONS According to the findings of this study, cycloplegia reduces the thickness of the crystalline lens and subsequently causes an increase in the ACD. Cycloplegia-related ocular biometric changes were different by type of refractive error.

Research paper thumbnail of Relation Between Near Work and Ocular Biometric Components

International journal of occupational hygiene, 2015

ORIGINAL ARTICLE To determine the association between ocular biometric components and near work i... more ORIGINAL ARTICLE To determine the association between ocular biometric components and near work in bank employees.This study was conducted as an analytical cross-sectional study. A group of bank employees and a control group were randomly selected. After applying the inclusion criteria, all selected subjects had a set of examinations including refraction, uncorrected and corrected visual acuity, slit lamp biomicroscopy and ophthalmoscopy. Then ocular biometric indices were measured using a Nidek biometer (US 800).Mean spherical equivalent was -0.53 (95%CI: -0.7 to -0.36) diopter (D) in bank employees and 0.09(95%CI: -0.05 to 0.23) D in the control group(p<0.001). After adjusting for age and gender, axial length and vitreous chamber depth were significantly longer in bank employees. In a logistic regression model, near work significantly correlated with increasing axial length 1.89(95%CI: 1.3 to 2.75) and decreasing corneal radius of curvature 0.22 (95%CI: 0.08 to 0.63) after adju...

Research paper thumbnail of Effect of Occlusion Therapy on Visual Acuity, Contrast Sensitivity and Stereopsis in Amblyopia

Purpose: To determine the effect of occluding a normal eye on visual acuity, contrast sensitivity... more Purpose: To determine the effect of occluding a normal eye on visual acuity, contrast sensitivity and stereopsis in amblyopic school children. Methods: Amblyopic children from primary schools of region 2 in Mashhad were identified and referred to Optometry Clinics of Mashhad Medical University through a screening program. Informed consent was obtained from the parents. All subjects underwent an ophthalmologic examination including visual acuity, subjective refractive error, biomicroscopy and funduscopy. Best-corrected visual acuity (BCVA), contrast sensitivity and stereopsis were measured by Snellen E chart, Cambridge low contrast chart and Titmus stereotest , respectively. All tests were repeated 2 weeks, 1 month and 3 months after initial examination. Results: Of 1,947 children, 289 (14.8%) were amblyopic of whom 62 subjects were eventually enrolled for the study. BCVA in the amblyopic eye was less than 3/10 in 25.8% of subjects before treatment however all children had BCVA of 3/...

Research paper thumbnail of The prevalence of Amblyopia in a young Population

British Journal of Visual Impairment

Purpose: The aim of this study was to determine the prevalence of amblyopia and its determinants ... more Purpose: The aim of this study was to determine the prevalence of amblyopia and its determinants in Iranian students above 18 years. Methods: In this university-based cross-sectional study, multi-stage cluster sampling was used to select participants. After selecting the students, visual acuity, objective, and subjective refraction were measured and the best-corrected visual acuity was determined. Results: We evaluated 1462 individuals with a mean age of 22.8 ± 3.1 years in this study, of whom 73% were female. The prevalence of amblyopia was 2.19% (95% confidence interval [CI]: [1.43, 2.93]), of which 6.2% was strabismic, 71.8% was refractive (isometropic and anisometropic), and 22.0% was mix (strabismic and anisometropic). No difference was observed in the prevalence of amblyopia between boys and girls (p value = 0.315). The prevalence of amblyopia was 3.93%, 1.71%, 3.79%, and 0% in the age group 18–20, 21–25, 26–30, and above 30 years, respectively (p value = 0.071). Conclusion: The results of this study, as the first study investigating the prevalence of amblyopia in Iranian adults, showed a rather higher prevalence of amblyopia in Iranian university students compared to other studies on adults in other countries. Moreover, similar to some other studies, refractive amblyopia had a higher prevalence than other types.

Research paper thumbnail of Tear film secretion and stability in welders

Contact Lens and Anterior Eye

PURPOSE Welders are prone to ocular injuries and ocular surface problems due to exposure to ultra... more PURPOSE Welders are prone to ocular injuries and ocular surface problems due to exposure to ultraviolet light. The aim of this study was to evaluate the tear film comprehensively and assess objective and subjective indices of dry eye in welders. METHODS In this historical cohort, welders with at least 5 years of experience were compared with controls. A complete evaluation of ocular health was done for all participants. The Schirmer test (invasive and non-invasive) and Invasive Tear Break-Up Time (ITBUT) were applied for objective evaluation and the Ocular Surface Disease Index (OSDI) was used for subjective assessment of the tear film status. The results were compared between the two groups using the SPSS software. RESULTS The results of 140 welders (mean age: 46.66 ± 13.01 years) and 172 controls (mean age: 45.05 ± 12.61) were analyzed. The values of the Schirmer test and ITBUT were significantly lower in welders than controls; the difference was more prominent for the Schirmer test as compared to TBUT (Schirmer difference = 4.98 mm, ITBUT difference = 2.23 s). OSDI values were also significantly lower in welders than controls (P < 0.001). Considering a cut-off point of 12, 81.2% of welders had degrees of dry eye which was severe in 46.2% while 35.5% of controls had dry eye. CONCLUSION The results indicate that the percentage of dry eye and tear problems is far higher in welders than non-welders. Most of the affected welders have severe dry eye. It seems that the main reason for dry eye in these people is aqueous deficiency.