Corneal response to rigid contact lens wear (original) (raw)
Related papers
Investigative Ophthalmology & Visual Science, 2003
To investigate topographical thickness changes of the epithelium and total cornea measured with optical coherence tomography (OCT) after overnight wear of rigid gas-permeable lenses. METHODS. Reverse geometry design CRT (Dk ϭ 100) rigid (test) lenses (Paragon Vision Sciences, Mesa, AZ) were randomly fitted on one eye of each of 20 neophyte subjects (mean age, 24.6 Ϯ 2.7 years) and the other eye was fitted with an alignment tricurve rigid lens of the same material (control). Epithelial and total corneal thickness was measured at intervals of 10°a cross a 10-mm zone of the horizontal meridian of the cornea, before and after overnight wear. Refractive error was measured with an autorefractor. These measurements were repeated 20 and 60 minutes and 3, 6, and 12 hours after lens removal.
Contact Lens-Induced Corneal Peripheral Swelling Differences With Extended Wear
Cornea, 2008
Purpose. To compare the repeatability and agreement of corneal thickness measurements using central and peripheral ultrasound and Orbscan pachymetry to detect contact lens (CL)-induced corneal swelling after extended wear (EW). Methods. Corneal thickness was measured in five corneal locations (central, superior, inferior, nasal, and temporal) with ultrasound and Orbscan pachymetry 1 week before CL wear commenced and after 1 week of EW. High oxygen permeability (lotrafilcon A) and low oxygen permeability (etafilcon A) CL were randomly fitted for EW in the right and left eyes of 20 subjects with normal ocular health to induce different amount of corneal swelling. Results. Poor repeatability and poor agreement in peripheral ultrasound and Orbscan pachymetry was found between corneas with and without corneal swelling. Ultrasound coefficients of repeatability (central, superior, inferior, nasal, and temporal) in corneas without (0.
Confocal microscopic observations of the human cornea following overnight contact lens wear
Clinical and Experimental Optometry, 2002
Background: Striae and folds are observed with a slitlamp biomicroscope in the cornea following overnight contact lens wear. These phenomena are poorly understood. The aim of this study is to employ confocal microscopy to observe and document these and other morphological changes in the human cornea following overnight contact lens wear. Methods: Slitlamp biomicroscopy, slit-scanning confocal microscopy and ultrasonic pachometry were performed on both eyes of 13 subjects (3M, 10F, age 24 ± 3 years) before and after eight hours overnight wear of a -3.00 D Bausch & Lomb one day disposable soft contact lens (Dk/t = 15.1 x 10 -9 {cm/sec} x {ml O 2 /ml x mmHg}) in one eye; the other non-lens-wearing eye acted as a control. Results: Following sleep, both corneas were swollen (lens-wearing eye 11.8 ± 3.8 per cent; control eye 2.1 ± 1.9 per cent) and the stroma of both corneas displayed an apparent reduction in keratocyte density (lens-wearing eye 21 per cent; control eye 10 per cent). Folds were observed with the slitlamp biomicroscope and long, straight, dark, orthogonal lines were observed with the confocal microscope, in the posterior stroma of the oedematous lens-wearing eyes. Such features were not observed in the control eyes. The keratocytes appeared less distinct with greater levels of corneal oedema. Conclusion: The apparent loss of keratocytes following overnight lens wear is an optical artefact that can be explained in terms of corneal oedema causing volumetric tissue expansion and a loss of optical clarity, which hampers keratocyte detection. These findings place the onus on researchers postulating a loss of stromal keratocytes following clinical interventions, such as contact lens wear, to account for the effects of oedema.
The morphology of corneal endothelial cells in long term soft contact lens wearers in Kuala Lumpur
Contact Lens and Anterior Eye, 2021
To analyse and compare the alterations in corneal endothelium morphology induced by different materials and durations of wearing soft contact lenses (CL) among young adults living in Kuala Lumpur. Methods: Healthy soft CL wearers were invited to participate in this study. Visual acuity (VA) was measured using the Snellen chart, and subjective refraction was performed using cross-cylinder technique. Standard ocular assessments were conducted using a slit lamp biomicroscope and morphology of corneal endothelial cells (endothelial cell density, ECD, coefficient variation, COV, hexagonality, HEX and central corneal thickness, CCT) were evaluated using a non-contact specular microscope. Statistical analysis was conducted using ANOVA and data from the right eye only is included. Results: A total of 72 subjects (32 SiHy and 40 HCL wearers) and 24 non-CL wearers (control) participated in this study. The gender distribution for study subjects was 13 males and 59 females, with a mean age 22.15 ± 1.84 years old. The mean refraction was −1.86 ± 1.25DS. The duration of wearing CL ranged from 1 to 9 years. Subjects were later divided into 2 groups following duration of CL wear: Group 1 (< 5 years) and Group 2 (≥5 years) for analysis purposes. Statistical analysis showed significant alterations in ECD, COV and HEX of CL wearers (p < 0.05), with more changes found in HCL and Group 2 wearers. No significant change was found in CCT. Conclusion: This study concludes that soft CL wear induced alterations in the morphology of corneal endothelial cells. Contact lens material and duration of CL wear (in years) are factors that affect the alterations. Optometrists are recommended to regularly evaluate the morphology of corneal endothelial cells in CL wearers and provide necessary intervention when required.
Epithelial permeability reflects subclinical effects of contact lens wear
British Journal of Ophthalmology, 1998
Aims-Recently, it was reported by the authors that a single drop fluorophotometric technique for estimating corneal epithelial permeability (P dc ) to fluorescein is not suYciently precise for monitoring permeability changes in individual patients, but may be useful for evaluating mean diVerences in P dc in population based research. To determine whether this technique provides a more sensitive index of epithelial integrity compared with conventional clinical assessments, the eVects of mild corneal trauma on P dc , the slit lamp appearance of the cornea, and corneal thickness (CT) were assessed.
Investigative Opthalmology & Visual Science, 2003
PURPOSE. To study the effects of extended contact lens wear (EW) on the movement of basal epithelial cells toward the corneal surface. METHODS. Rabbits (n ϭ 32) were injected with 5-bromo-2deoxyuridine (BrdU) to label a group of proliferating basal epithelial cells, and, 24 hours later, one randomly chosen eye was fitted with a low-or medium-oxygen-transmissible (Dk/t) rigid gas permeable (RGP) contact lens, while the other eye served as the control (n ϭ 28). Four rabbits were not fitted with any contact lens. Rabbits were euthanatized at different time points and the corneal epithelium was immunocytochemically stained for BrdU and/or Ki-67 and counterstained with propidium iodide or Syto 59. Corneal flatmount tissues were examined three dimensionally under a laser confocal microscope and the location of each BrdU-labeled cell in the corneal epithelium (basal or suprabasal) was determined. RESULTS. Four days after injection of BrdU, both low-(P Ͻ 0.001) and medium-Dk/t RGP (P Ͻ 0.001) lens groups showed significantly more BrdU-labeled cells in the basal cell layer than in the control eyes. Six days after injection of BrdU, a small percentage of BrdU-labeled cells (Ͻ0.5%) were Ki-67 positive. CONCLUSIONS. Within 6 days, the majority (80%) of BrdU-labeled basal cells became terminally differentiated and rarely divided secondarily in the central epithelium. Short-term use of lowand medium-Dk/t RGP EW contact lenses slows the normal movement of basal epithelial cells toward the surface in the central cornea. This is consistent with known EW-lens-induced decreases in corneal epithelial basal cell proliferation and surface cell exfoliation. Overall, the data suggest that EW lenses significantly inhibit the normal homeostatic turnover rate of the corneal epithelium.
Variations in Central Corneal Thickness During the First Year of Contact Lens Wear
Acta Ophthalmologica, 2009
Variations in central corneal thickness during the first year of hard, hydrophilic or silicone lens wear are reported. The mean corneal swelling after 1/2,3 and 6 months was 4.7-3.0% in the first 2 groups (P < 0.001-P = 0.005), but only 1.3-0.8% in the latter group (P = 0.01 1-0.050). These differences were statistically significant (P < 0.001-P = 0.046) and are ascribed to a higher oxygen tension under the silicone lenses. An overall reduction of corneal oedema was noted after 1/2 month (P = 0.025). One year after lens fitting a similar and not significant corneal swelling was found in the 3 lens groups. In addition to an initial 'osmotic' adaptation our results indicate that a further corneal adaptation to hard and hydrophilic lenses may take place between 6 and 12 months after lens fitting. Development of lens intolerance was not correlated to the degree of corneal oedema after 112 month of lens wear.
Clinical optometry, 2018
Purpose: Soft contact lens wear is most frequently associated with morphologic changes in corneal endothelial cells, but the data are scarce in Asians. This study aimed to evaluate changes in corneal endothelial cell morphology after 6 months of wearing soft hydrogel contact lenses (SH) in young myopic adults living in Kuala Lumpur. Patients and methods: Forty-eight subjects were included in the study, 24 were fitted with SH contact lenses (A) and the rest were prescribed with glasses (B). Refraction was conducted subjectively and standard contact lens fitting protocol was followed. Corneal endothelial cell morphology (endothelial cell density, ECD; coefficient of variation, COV; cells' hexagonality, HEX; and central corneal thickness, CCT) was evaluated using specular microscope. Data were collected at baseline and after 6 months of lens wear. Results: Mean age of all subjects was 21.23±1.30 years. All results are shown at baseline and 6 months, respectively. Mean refraction for A was-2.16±0.97 diopter sphere (DS) and-2.05±1.03 DS (P=0.49); for B was-2.72±1.51 DS and-2.73±1.51 DS (P=0.58). Mean ECD (cell/mm 2) for A: 3104.19±237.30 and 3107.23±237.51 (P=0.07); for B: 3011.56±227.95 an d 2983.83±244.55 (P=0.33). COV (%) for A: 46.52±8.63 and 48.53±10.65 (P=0.06); for B: 46.93±9.31 and 46.14±10.65 (P=0.88). HEX (%) for A: 46.21±10.12 and 45.15±10.01 (P=0.08); for B: 46.21±10.12 and 45.15±10.01 (P=0.12). CCT (µm) for A: 520.33±0.04 and 525.70±0.05 (P=0.41); for B: 532.00±0.04 µm and 530.00±0.05 µm (P=0.40). Conclusion: This study found no significant change in corneal endothelial cell morphology after 6 months of wearing SH contact lenses. This is probably due to better oxygen permeability of the contact lens material, good compliance, and short wearing period.