Excimer laser photorefractive keratectomy for myopia: 12 month follow-up

Abstract

SUMMARYA prospective study of excimer laser photo refractive ker atectomy was performed with the aim of correcting a range of myopic errors between -1.00 and -10.00 dioptres . Corneal healing was monitored through the first post-operative year by serial assessments of refrac tion, contrast sensitivity, corneal haze, pachymetry and keratometry. Eighty-one patients were recruited for the study. At 12 months 81 % were within ± 1.00 dioptre of desired emmetropia and with unaided vision of 6/12.Contrast sensitivity was found by Pelli-Robson assess ment to be reduced throughout the 12 months and regres sion analysis predicted recovery by 2 years. At 12 months, however, only 15 % of patients �ere found to have lost a single line of best corrected Snellen acuity. Predictability of results was found to be greatest for initial errors less than -4.00 dioptres. No serious complications were observed during the follow-up period, but refraction had not stabilised in all cases and patients remain under review.

Fortnightly Review: Treating myopia with the excimer laser: the present position

“…Over the past two years these findings have been confirmed by other centres using different laser systems (table I) 28 30 33 39 40 41 42 43 44 45. Most myopic people have less than −6.00 dioptres of myopia, and in these patients predictability and stability of refractive outcome are relatively good 24 25 26 27 28 30 33 39 40 41 42 43 44 45. In addition, while photorefractive keratectomy has side effects (box 1), few sight threatening complications have been encountered 23 34.…”

“…Gartry et al, however, reported considerable individual variation in response to this treatment because of differences in wound healing from patient to patient, and in particular they found that it was much more difficult to treat moderate to high myopia (greater than around −6.00 D) 24 25 26. Over the past two years these findings have been confirmed by other centres using different laser systems (table I) 28 30 33 39 40 41 42 43 44 45. Most myopic people have less than −6.00 dioptres of myopia, and in these patients predictability and stability of refractive outcome are relatively good 24 25 26 27 28 30 33 39 40 41 42 43 44 45.…”

“…The first British procedures started at St Thomas's Hospital in November 198924 25 26 at around the same time as those in the United States,27 and at Moorfields Eye Hospital in December 1990 28. Since then, tens of thousands of patients have been treated worldwide.…”

“…Mean follow up is considerably less than five years, and the procedure therefore should be regarded as experimental and investigational. However, the available data suggest that serious longer term side effects (such as late onset sight threatening infection, corneal decompensation, or serious permanent scarring) are unlikely, though not impossible 24 25 26 27 28 30 33 39 40 41 42 43 44 45. To date, because of potential long term problems, the American Food and Drug Administration has taken a cautious approach, and the procedure has yet to gain its approval.…”

Changes in Contrast Sensitivity Function and Ocular Higher Order Aberration by Conventional Myopic Photorefractive Keratectomy

“…[1][2][3][4] In this study, we found that a reduction in contrast sensitivity signifi cantly correlated with the surgically induced increases in ocular higher order wavefront aberrations. Because there was no case of moderate to severe corneal subepithelial haze in our patients, the current data indicate that increases in ocular higher order wavefront aberrations led to a decline of contrast sensitivity function after PRK.…”