Excimer laser photorefractive keratectomy for hyperopia: 7.5-year follow-up
Accepted 13 October 2004.
Purpose
To report the results of a long-term prospective study to evaluate refractive stability and safety of hyperopic photorefractive keratectomy (H-PRK).
Setting
Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.
Methods
Twenty-one patients (49%) (40 eyes) of cohort of 43 patients who participated in 1 of the first clinical trials of H-PRK were assessed at a mean follow-up of 90.7 months (range 62 to 106 months). The H-PRK was performed using a Summit Technology Apex Plus Excimer laser (Summit Technology, Inc.). The mean preoperative spherical equivalent refraction (SEQ) was +4.70 diopters (D) (range +2.00 to +7.50 D). Patients were allocated to 1 of 4 treatment groups based on their preoperative refraction and received 1 of the following spherical corrections: +1.50 D, +3.00 D, +4.50 D, or +6.00 D.
Results
At 7.5 years, the refractive correction remained stable with a mean difference in SEQ between 1 year and 7.5 years of +0.28 D. The mean manifest SEQ was +0.83 D (range +5.00 to −3.00 D). Sixty-seven percent of eyes having corrections of +1.50 D and +3.00 D were within ±1.00 D of the predicted correction. Predictability was poorer with +4.50 D and +6.00 D corrections, with 40% of eyes within ±1.00 D of that expected. An improvement in uncorrected near acuity was achieved in 35 eyes (87.5%), and 35 eyes (87.5%) showed an improvement in uncorrected distance acuity from preoperative levels. Best spectacle-corrected visual acuity (BSCVA) was unchanged or improved from preoperative values in 25 eyes (62.5%). Three eyes (8%) lost 2 lines of Snellen BSCVA, which in 2 cases was attributable to cataract formation. A peripheral ring of haze, 6.5 mm in diameter, appeared in most eyes. Its intensity was greatest at 6 months and then diminished with time. In 10 eyes (25%), remnants of the haze ring were evident at 7.5 years and subepithelial iron rings, 6.5 mm in diameter were evident in 26 eyes (70%). No patient complained of night-vision problems and no eye developed ectasia.
Conclusions
In H-PRK, refractive stability achieved at 1 year was maintained up to 7.5 years with no evidence of hyperopic shift, diurnal fluctuation, or late regression. Peripheral corneal haze decreased with time but was still evident in a number of eyes at the last follow-up visit.
From the Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom
Reprint requests to David P.S. O'Brart, MD, FRCOphth, FRCS, Department of Ophthalmology, St. Thomas' Hospital, Lambeth Palace Road, London, SE1 7EH, United Kingdom.
Supported by the Iris Fund for Prevention of Blindness in relation to both the purchase and maintenance of the laser.
Professor Marshall was a consultant for Summit Technology. No other author has a proprietary or financial interest in any material or method mentioned.
ABSTRACT