Excimer laser photorefractive keratectomy for the correction of myopia.

AIM OF STUDY: To ascertain the efficacy, predictability, safety and stability of photorefractive keratectomy (PRK) for the correction of myopia. METHODS: Nine-hundred and seventy-one eyes of 628 patients had PRK performed for the correction of myopia. The mean pre-operative myopia was -5.7 D +/- 2.21 D (range -1.0 D to -15.25 D). The mean attempted correction was -5.0 D +/- 1.9 D (range -1.0 D to -9.90 D). RESULTS: Four-hundred and sixty-seven eyes had a follow-up of 6 months or more. Ninety-three percent of low myopic eyes (pre-operative myopia of less than or equal to 6.0 D) and 75% of high myopic eyes (pre-operative myopia of more than 6.0 D) attained an unaided visual acuity of 6/12 or better. Seventy-four percent of low myopic and 50% of high myopic eyes were within 1 D of the intended correction. The mean post-operative refraction at 6 months was 0.60 D +/- 1.46 D. Eight eyes in the high myopia group and 1 eye in the low myope group lost 2 or more lines or best-corrected visual acuity. CONCLUSION: PRK was safer and produced better results for low myopes.

Electroretinographic profile in emmetropic Singaporean eyes.

OBJECTIVES: To characterise the electroretinographic (ERG) profile in 70 Singaporean emmetropic eyes. METHOD: Seventy eyes of thirty-five patients with refractive error of -1.00D or less and with a normal ophthalmic examination were chosen. They were subjected to three flash patterns generated with a Nihon-Kohden Flash Stimulator. The results were captured on a Nihon-Kohden Neuropack 8. RESULTS: The mean age of the patients was 25 years (range 20 to 30). The mean spherical refractive error was -0.3D (range 0D to -1.00D). For the scotopic dim flash, the mean amplitude for the 'b' wave was 304.6 +/- 69.2 mu v (range 175 mu v to 469 mu v) and the mean latency was 47.56 +/- 4.87 ms (range 41.2 ms to 62.0 ms). For the scotopic bright flash, the mean amplitude for the 'b' wave was 469.54 +/- 127.15 mu v (range 257 mu v to 750 mu v) and the mean latency was 40.54 +/- 3.91 ms (range 32.0 ms to 48.9 ms). In the flicker response, the mean amplitude for the 'b' wave was 34.19 +/- 12.97 mu v (range 14 mu v to 64 mu v) with mean latency at 34.46 +/- 0.58 ms (range 33.1 ms to 35.9 ms). CONCLUSION: With ERG normal values so generated, comparisons with these can then be made for abnormal cases.