Biometry, Refractive Errors, and the Results of Cataract Surgery: A Large Sample Study (original) (raw)
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Revista Brasileira de Oftalmologia, 2024
Objective: To evaluate intraocular lens power calculation and postoperative refractive errors in patients with high myopia undergoing cataract surgery, comparing predicted target refraction and actual postoperative refraction measured 30 days after surgery with SRK/T formula. Methods: This retrospective analysis comprised 39 eyes of 31 patients undergoing cataract surgery through phacoemulsification with in-the-bag IOL implantation. Axial length was measured by partial coherence interferometry or immersion ultrasound biometry, with measurements greater than 26 mm and preoperative myopia greater than -6.0 D Manifest refraction was performed at the 1-month postoperative visit, and the spherical equivalent was analyzed. Results: After analysis of 39 eyes of 31 patients undergoing cataract surgery with a mean axial length of 30.4 (standard deviation of 2.2) mm, the mean preoperative refractive spherical equivalent was -15.6 (standard deviation of 7.6) D, ranging from -24.0 to -13.4 D. At 30 days postoperatively, the mean spherical equivalent was -0.35 (standard deviation of 1.1) D, ranging from -2.4 to 2.50 D. Conclusion: We encountered a correlation between the absolute refractive error and the dioptric power of the intraocular lens. Against expectations, in our study, ultrasound biometry yielded better results than the optical biometer device, probably due to the small number of patients undergoing optical biometry, suggesting that well-performed immersion biometry can still produce satisfactory results.
Ocular biometry characteristics in cataract surgery candidates: A cross-sectional study
Medical Hypothesis, Discovery & Innovation in Ophthalmology, 2021
Background: This study was conducted to investigate ocular biometry parameters in cataract surgery candidates in northern Tehran, Iran using OA-2000 biometry device. Methods: In this cross-sectional study, values of ocular biometry parameters, including axial length (AL), anterior chamber depth (ACD), mean corneal curvature (mean K), lens thickness (LT), corneal astigmatism (CA), and white-to-white (WTW) of 818 eyes with cataracts, were measured using the OA-2000 biometry device (Tomey, Nagoya, Japan). The participants were divided into six age subgroups, in 10-year intervals. Finally, the values of the biometry parameters were calculated, and the trend of changes was examined for both age and sex subgroups. Results: The mean ± standard deviation (SD) of age of the participants was 63.82 ± 13.25 years. Mean ± SD of biometry parameters were as follows: AL, 23.36 ± 1.55 mm; ACD, 3.09 ± 0.40 mm; LT, 4.45 ± 0.55 mm; mean K, 44.51 ± 1.72 D; CA, 1.06 ± 0.94 D; and WTW, 11.81 ± 0.45 mm. Mo...
Effect of visual acuity on biometry prediction error after cataract surgery
Journal of Cataract & Refractive Surgery, 2003
To determine the effect of visual acuity on biometry prediction error. Setting: Postgraduate teaching hospital. Methods: The study was an observational case series of the first operated eye of 2149 consecutive patients who had cataract surgery. Biometry prediction error was defined as the difference between the planned refraction determined by biometry and the spherical equivalent of the final refraction. The principal outcome measure was the percentage of eyes within Ϯ1.00 diopter (D) of the intended refraction. This outcome was calculated for patients with visual loss caused by cataract alone, defined as eyes with a postoperative acuity of 6/6 or better, and eyes with different levels of postoperative visual acuity. Results: Complete data were available for 1978 eyes (92%). Of these, 1438 (73%) were within Ϯ1.00 D of the intended refraction. When the final corrected visual acuity was 6/6 or better, the percentage of eyes within Ϯ1.00 D of the predicted refraction was at least 78%. When the preoperative acuity was worse than 6/60, 74% in the counting fingers group and 69% in the hand movements group with a final corrected acuity of 6/6 or better were within Ϯ1.00 D. This trend bordered on statistical significance (P ϭ .05). There was a rapid reduction in the percentage of eyes within Ϯ1.00 D of the intended refraction as the postoperative acuity decreased because of ocular comorbidity, with a statistically significant difference between eyes with a postoperative acuity of 6/6 or better and each group with an acuity of 6/9 or worse (PϽ.01). Conclusions: In eyes without visually significant ocular comorbidity, cataract must reduce vision to 6/60 or worse before there is an increase in biometry prediction error. In contrast, ocular comorbidity that reduces the postoperative acuity causes an early and marked increase in biometry prediction error.
Comparative Study of Manual Versus Automated Biometry on Refractive Outcome of Cataract Surgery
Journal of Evolution of Medical and Dental Sciences
BACKGROUND Intraocular Lens (IOL) power calculation is the most important step to achieve best refractive outcome in cataract surgery. Various studies had revealed that about 54% of the error in predicted refraction occurred due to inaccuracy in axial length measurement alone. Therefore, axial length measurement is the most important step to minimise these errors. The aim of this study was to compare IOL power calculation using a manual method (Applanation ultrasound A-Scan and Keratometry) with the automated method (Optical biometry). MATERIALS AND METHODS It was a prospective, comparative study. In this study, 200 eyes of 196 patients were analysed in the Department of Ophthalmology. Each eye underwent measurement by both methods, with manual method (Applanation Ultrasound A-Scan and manual Keratometer) and with automated optical biometry. Axial length and Keratometric readings were obtained and IOL power calculation was done by both the methods. Patient underwent clear corneal phacoemulsification cataract surgery within the IOL implantation in all the cases, then postoperative autorefraction was noted in all cases in follow-ups. RESULTS The Mean Axial Length calculated by optical A scan was 23.02±1.00 mm and by ultrasound A scan was 22.93±1.03 mm. The mean difference in axial length between optical system and Ultrasound A scan was 0.087±0.039 mm, which is statistically not significant (p value 0.19). However, differences in axial length measurement were more when compared, for short eyes, by two devices. After analysis of Bland-Altman plot. All differences were within two standard deviations (95% confidence level) from mean differences (0.0869±0.038 mm, i.e. between 0.0096 mm and 0.1641 mm). The regression line between the two methods, Pearson's correlation coefficient 'r' is 0.999, which evaluates excellent agreement of axial length measurement between two methods. The differences in mean IOL power between automated method and manual method was 0.43±0.38 D, which was statistically and clinically insignificant (p value 0.09). CONCLUSION To measure axial length and IOL power, optical biometry is very precise and interchangeable with ultrasound method. Optical biometry in short eyes gives better result in axial length measurement as compared to ultrasound A-scan.
Journal of Nepalgunj Medical College, 2022
Introduction: Proper preoperative biometry in cataract surgery provides expected postoperative uncorrected visual outcome. Astigmatism is one of the major problems to achieve best postoperative unaided visual acuity. Aims: To determine the distribution of biometric parameter and unaided visual outcome in the cataract patients operated at Nepalgunj medical college, Banke, Nepal. Methods: The patients who underwent cataract surgery between January 2019 and December 2020 at Nepalgunj medical college were studied. Patient’s demographic parameter, keratometric value, anterior chamber depth, lens thickness and axial length data, type of surgery, preoperative and post-operative visual acuity and other clinical details were collected and analyzed. Results: This study enrolled 261 eyes of 261 patients who had undergone cataract surgery. The mean age of patients was 60.8 ± 14.62 years. The mean corneal astigmatism was 1.30±1.43 D. Corneal astigmatism was higher than 1.00 D in almost 40% of ca...
Revista Brasileira de Oftalmologia, 2013
To analyze refractive results in postoperative cataract surgery in eyes previously submitted to keratotomy using Haigis formula and data provided by IOL Master ® optical biometer. Methods: The measurements for IOL calculation were obtained through optical biometry by partial coherence interferometry 5.4 and 5.5 version) that provides us with the axial length, the central keratometry of 2.5mm, white-to-white diameter and anterior chamber anatomical depth. The formula chosen was Haigis. The surgical technique applied was with the scleral incision at 1.5 mm from the limbus, with scleral-corneal tunnel of 2.2 mm wide, phacoemulsification using INFINITI Ozil ® -Alcon and implantation of hydrophobic acrylic aspheric intraocular lens -SN60WF ® -Alcon. Results: We studied 20 eyes submitted to keratotomy in the past and currently with cataract with indication for cataract surgerywith intraocular lens implantation using phacoemulsification. Postoperative spherical equivalent was plano in 40% of the eyes and lower than -1.00 in 85% of the eyes. Conclusion: The optical biometry by partial coherence interferometry associated with Haigis formula is a valid alternative in IOL calculation for eyes submitted to keratotomy. The refractive results are highly predictable and reproducible.
BMJ Open Ophthalmology, 2019
ObjectivePrediction errors are increased among patients presenting for cataract surgery post laser vision correction (LVC) as biometric relationships are altered. We investigated the prediction errors of five formulae among these patients.Methods and analysisThe intended refractive error was calculated as a sphero-cylinder and as a spherical equivalent for analysis. For determining the difference between the intended and postoperative refractive error, data were transformed into components of Long's formalism, before changing into sphero-cylinder notation. These differences in refractive errors were compared between the five formulae and to that of a control group using a Kruskal-Wallis test. An F-test was used to compare the variances of the difference distributions.Results22 eyes post LVC and 19 control eyes were included for analysis. Comparing both groups, there were significant differences in the postoperative refractive error (p=0.038). The differences between the intended...
Ocular biometric measurements in cataract surgery candidates in Portugal
PloS one, 2017
Describe the ocular biometric parameters and their associations in a population of cataract surgery candidates. A cross-sectional study of 13,012 eyes of 6,506 patients was performed. Biometric parameters of the eyes were measured by optical low-coherence reflectometry. The axial length (AL), mean keratometry (K) and astigmatism, anterior chamber depth (ACD) (epithelium to lens), lens thickness (LT), and Corneal Diameter (CD) were evaluated. The mean age was 69 ± 10 years (44-99 years). Mean AL, Km, and ACD were 23.87 ± 1.55 mm (19.8-31.92 mm), 43.91 ± 1.71 D (40.61-51.14 D), and 3.25 ± 0.44 mm (2.04-5.28 mm), respectively. The mean LT was 4.32 ± 0.49 mm (2.73-5.77 mm) and the mean CD was 12.02 ± 0.46 mm (10.50-14.15 mm). The mean corneal astigmatism was 1.08 ± 0.84 D (0.00-7.58 D) and 43.5% of eyes had astigmatism ≥ 1.00 D. Male patients had longer AL and ACDs (p < .001) and flatter corneas (p < .001). In regression models considering age, gender, Km, ACD, LT, and CD, a longe...
Evaluation of postoperative refractive error correction after cataract surgery
PLOS ONE, 2021
Suboptimal cataract surgery outcomes remain a challenge in most developing countries. In Ghana, about 2 million people have been reported to be blind due to cataract with about 20% new cases being recorded yearly. The aim of this study was to evaluate postoperative correction of refractive errors after cataract surgery in a selected eye hospital in Ashanti Region, Ghana. This was a retrospective study where medical records of patients (aged 40–100) who reported to an eye hospital in Ghana from 2013–2018 were reviewed. Included in the study were patients aged ≥40 years and patients with complete records. Data on patient demographics, type of surgery, intra-ocular lens (PCIOL) power, availability of biometry, postoperative refraction outcomes, pre- and postoperative visual acuity were analyzed. Data of two hundred and thirteen eyes of 190 patients who met the inclusion criteria were analyzed. Descriptive analysis and Chi-square test were carried out to determine the mean, median, stan...