Effect of aging on optical quality and intraocular scattering using the double-pass instrument.

PURPOSE: To assess the effect of aging on optical quality in a normal population. METHODS: We prospectively examined 100 normal eyes of 100 healthy volunteers (50 men, 50 women; ages, 20-69 years; mean age ± standard deviation, 44.6 ± 15.5 years). We quantitatively assessed the values of MTF cutoff frequency, Strehl ratio, and objective scattering index (OSI), using an Optical Quality Analysis System™ (Visiometrics, Terrassa, Spain). We took these measurements three times each, and the mean value obtained was used for statistical analysis. We investigated the relationships between subject age and these optical quality parameters. RESULTS: The mean MTF cutoff frequency, Strehl ratio, and OSI, were 27.76 ± 8.41, 0.17 ± 0.05, and 1.29 ± 0.76 cycles/degree, respectively. We found a significant negative correlation between subject age and MTF cutoff frequency (Pearson's correlation coefficient r = -0.606, p < 0.001), and between age and Strehl ratio (r = -0.649, p < 0.001). We also found a significant positive correlation between subject age and OSI (r = 0.691, p < 0.001). CONCLUSIONS: The MTF cutoff frequency and the Strehl ratio are significantly decreased, and the OSI is significantly increased, by aging, indicating that the optical quality of the eye is degraded in older subjects.

Factors influencing the changes in coma-like aberrations after myopic laser in situ keratomileusis.

PURPOSE: To assess factors affecting changes in coma-like aberrations after myopic laser in situ keratomileusis (LASIK). METHODS: We retrospectively examined 91 eyes of 48 patients undergoing LASIK (mean patient age ± standard deviation, 29.6 ± 8.1 years; gender, 29 male and 19 female; manifest refraction, -4.76 ± 1.42 diopters). We quantitatively assessed the values of coma-like aberrations for 4-mm and 6-mm pupils using a Hartmann-Shack aberrometer before and 3 months after surgery. Multiple regression analysis was used to assess the relevant factors of the changes in coma-like aberrations. RESULTS: The mean changes in coma-like aberrations for 4-mm and 6-mm pupils were 0.08 ± 0.09 µm and 0.31 ± 0.30 µm, respectively. Explanatory variables relevant to the changes in coma-like aberrations were, in order of influence, amount of spherical equivalent correction (partial regression coefficient B = 0.022, p <0.001 for a 4-mm pupil, B = 0.090, p <0.001 for a 6-mm pupil), and surgical technique (B = -0.062, p = 0.01 for a 4-mm pupil, B = -0.169, p = 0.03 for a 6-mm pupil). No significant correlation was seen with other clinical factors such as age, gender, astigmatism correction, mean keratometric readings, central corneal thickness, or eye tracking (with or without). CONCLUSIONS: High myopic eyes requiring larger amounts of laser correction and eyes undergoing conventional LASIK tend to induce more coma-like aberration after surgery. Wavefront-guided LASIK may be a better surgical approach for preventing the induction of coma-like aberrations, especially in eyes with high myopia.

Clinical outcomes of photoastigmatic refractive keratectomy for the correction of residual refractive errors following cataract surgery.

PURPOSE: To assess the clinical outcomes of photoastigmatic refractive keratectomy (PARK) for the correction of residual refractive errors after cataract surgery. METHODS: This study evaluated 88 eyes of 66 consecutive patients with mean spherical equivalent refraction of -3.16±1.71 diopters (D) who underwent PARK to correct refractive errors after phacoemulsification with intraocular lens (IOL) implantation. Patient age at the time of surgery was 65.2±12.7 years. Safety, efficacy, predictability, stability, and adverse events of the surgery were assessed 1, 3, 6, and 12 months postoperatively. RESULTS: At 1 year postoperatively, uncorrected distance visual acuity and corrected distance visual acuity were 0.08±0.16 logMAR (Snellen 20/25) and -0.08±0.11 logMAR (Snellen 20/16), respectively. Safety and efficacy indices were 1.08±0.25 and 0.76±0.28, respectively. At 1 year, 68% of eyes were within ±0.50 D and 88% were within ±1.00 D of targeted correction. Manifest refraction changes of -0.06±1.06 D occurred from 1 week to 1 year. No vision-threatening complications occurred during the observation period. CONCLUSIONS: Photoastigmatic refractive keratectomy is safe and moderately effective in the correction of residual refractive errors in pseudophakic eyes, suggesting its viability as a surgical option for the treatment of such eyes.