Comparison of Ocular Aberrations in Two Hydrophobic and Hydrophilic Intraocular Lenses.

OBJECTIVE: To compare differences in higher-order aberrations (HOAs) between two standard spherical monofocal intraocular lenses (IOLs), the hydrophobic acrylic Alcon SA60AT (Bausch & Lomb), and hydrophilic acrylic Rayner Superflex (620H) (Rayner). METHODS: In this case series, sixty-eight eyes of 68 patients who underwent phacoemulsification cataract surgery were studied. In group 1 (n=39), the hydrophobic Alcon SA60AT IOL, and in group 2 (n=29), the hydrophilic Rayner Superflex (620H) IOL, were implanted. Distant best-corrected visual acuity was 20/20. Aberrometry was performed by the OPD Scan III (Nidek) on the undilated pupil and under mesopic conditions at the first and third months after surgery. RESULTS: There were no differences between the two groups in the mean total coma, total trefoil, total spherical aberration, and total HOAs in the two follow-up sessions (P>0.5, Independent t test). According to the repeated measure analysis of variance test results, total coma, total trefoil, total spherical aberration, and total HOAs significantly increased over time (P=0.033, P=0.017, P=0.005, P=0.004, respectively), although these changes were not significant between the two groups. CONCLUSION: It seems that IOL optically behaves differently in vivo versus in vitro conditions and environmental factors can affect the increase or decrease in HOAs by an IOL. Therefore, we should consider these factors and the effect of IOL material and design. Also, the implantation of the Alcon SA60AT and Rayner Superflex IOL does not induce higher HOAs in pseudophakic versus phakic eyes.

Normal range of cambridge low contrast test; a population based study.

PURPOSE: To determine the range of contrast sensitivity (CS) and its determinants in a normal population, Mashhad, Iran. METHODS: In this cross-sectional population based study, 4,453 individuals were invited of whom 3,132 persons agreed to participate (response rate, 70.4%). CS data from 2,449 eligible individuals were analyzed. CS was determined using the Cambridge low contrast square-wave grating test, and its associations with age, gender, best-corrected visual acuity (BCVA) and manifest refraction spherical equivalent (MRSE) refractive error, were analyzed. RESULTS: Mean age of the participants was 29.1±17.3 (range, 4-89) years and 66.4% were female. Mean CS was 239.6±233.3 and 234.6±228.6 cps in right and left eyes, respectively. Mean binocular CS was 310.9±249.0 cps. Multiple linear regression showed that CS was inversely correlated with older age (ß=-1.1, P<0.001), female gender (ß=-40.1, P<0.001), poorer BCVA (ß=-165.4, P<0.001), and severity of myopia (ß=-10.2, P<0.001). CONCLUSION: The normal range of Cambridge low-contrast grating test reported herein may serve as a reference for the general population in Iran. Our findings can be used for both research and clinical applications, particularly for evaluations of the outcomes of refractive surgery. In the current study, CS was lower in older subjects, myopic individuals and patients with lower BCVA.

Effects of mitomycin-C on tear film, corneal biomechanics, and surface irregularity in mild to moderate myopic surface ablation: preliminary results.

PURPOSE: To assess the effect of mitomycin-C (MMC) on the tear film, corneal biomechanics, and surface irregularity in surface ablation (photorefractive keratectomy [PRK]) for low to moderate myopia. SETTING: Refractive Surgery Unit, Farabi Eye Hospital, Tehran, Iran. DESIGN: Double-masked randomized clinical trial. METHODS: In patients with spherical equivalent myopia of -0.75 to -3.87 diopters (D) and astigmatism up to -1.75 D, the first eye was randomly assigned to the application of MMC 0.02% or a balanced salt solution for 15 seconds. The fellow eye received the alternate in a masked fashion after excimer photoablation. RESULTS: The study enrolled 60 patients. In fellow eyes, the changes in the tear-film index were comparable 1 month and 6 months postoperatively. There was no significant difference in changes in total higher-order aberrations, spherical aberration, coma, or Q values (Pentacam HR) between fellow eyes at 1 month and 6 months. There was a trend toward a higher asymmetry index at 1 month; however, a statistically significant drop was observed at 6 months in the MMC group (P<.01). It was hypothesized that stromal remodeling was delayed, but better, in MMC-treated eyes. No haze was recorded at 6 months in either group. CONCLUSION: Use of MMC in PRK did not appear to contribute significantly to surface irregularity, transient tear-film dysfunction, or biomechanical weakening of the cornea compared with PRK without MMC. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

The distribution of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth in an adult population of Shahroud, Iran.

BACKGROUND: Ocular biometric parameters can be influenced by race, ethnicity, and genetics; their differences across different populations can probably explain differences in refractive errors in these populations. The aim of this study is to determine the normal range of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth in the population of Shahroud in the north of Iran. METHODS: In the first phase of Shahroud Eye Cohort Study, the 40-64 year old population were sampled cross-sectionally; 6311 were invited and 5190 (82.2%) participated in the study. Biometric examinations were done using the LENSTAR/BioGraph (WaveLight AG, Erlangen, Germany) after vision tests and before cycloplegic refraction tests. Any type of eye surgery, extensive pterygium, and lack of cooperation were used as exclusion criteria, and analyses were done with data from 4869 eyes. RESULTS: We found a mean axial length of 23.14 mm (95% confidence interval [CI], 23.11-23.17), mean anterior chamber depth of 2.62 mm (95% CI, 2.60-2.63), mean lens thickness of 4.28 mm (95% CI, 4.27-4.29), and the mean vitreous chamber depth was 15.72 mm (95% CI, 15.70-15.75).Kolmogorov-Smirnov tests showed that the distribution of axial length, anterior chamber depth, lens thickness, and vitreous chamber depth significantly differed from normal; axial length and vitreous chamber depth demonstrated a leptokurtic distribution as well.Axial length, anterior chamber depth, and vitreous chamber depth significantly decreased with age, and lens thickness significantly increased with age (p < 0.001). All indices were significantly higher in men. CONCLUSIONS: The distributions of axial length, vitreous chamber depth, and lens thickness are reported for the first time in an Iranian adult population. Compared to other studies, axial length was in the mid range, nonetheless, studying axial length components showed that the Iranian population had smaller anterior chamber depth and lens thickness. Age and gender were significantly associated with all indices assessed in this study.