A Multicenter Trial of Photorefracti*ve Keratectomy for Residual Myopia after Previous Ocular Surgery (original) (raw)

Visual performance after excimer laser photorefractive keratectomy for high myopia

Taiwan Journal of Ophthalmology, 2017

PURPOSE: To evaluate the efficacy, safety, predictability, and visual performance of excimer laser photorefractive keratectomy (PRK) for myopia greater than −8 diopters (D). METHODS: Fifty-four patients (104 eyes) with myopia from −8D to −13D and cylinder up to −4D received surface ablation technique with the Allegretto wave version 1009-1 excimer laser to correct their refractive error. The patients were examined on days 1, 3, 7, and 14 and 1, 3, 6, and 12 months postoperatively. Visual acuity, manifest refraction, corneal haze, topography, intraocular pressure, contrast sensitivity, and wavefront aberration were evaluated. RESULTS: Twelve months postoperatively, 95% of eyes were within 1D of the intended correction. In addition, 94% of eyes had attained uncorrected distance visual acuity of 20/25 or better, and 98% of eyes had improved or remained their corrected distance visual acuity. All eyes exhibited barely detectable corneal haze which peaked during the 1 st month with a gradual reduction in the 3 rd month. Ninety-five percent of patients had no or only mild degree of night glare. CONCLUSIONS: Excimer laser PRK is an effective and predictive treatment for high myopia greater than −8D with or without astigmatism up to −4D. The incidence of complication is low. All patients who are candidates for laser in situ keratomileusis can be candidates for surface ablation, especially those with preoperative thinner cornea or higher risk of corneal flap complications.

Excimer laser Photorefractive Keratectomy (PRK): First report from the Italian study group

1991

To assess the visual and refractive results of excimer laser photorefractive keratectomy (PRK) in myopic astigmatism. Methods: Excimer laser PRK was performed using an Aesculap Meditec MEL 60 laser in 46 myopic astigmatic eyes. Preoperative corneal astigmatism was-1.50 D. (±0.50) in 7 eyes (15.2%);-2.50 D. (±0.50) in 14 eyes (30.5%);-3.50 D. (±0.50) in 13 eyes (28.3%);-4.50 D. (±0.50) in 8 eyes (17.4%); and-5.50 D. (±0.50) in 4 eyes (8.6%). Mean preoperative cylinder was-3.50 D. (±2.50). Mean preoperative sphere was-4.50 D. (±2.25). Pre and postoperative visual acuity, refraction, keratometer readings, corneal topography, intraocular pressure, and slit lamp findings were recorded. Results: By one year of follow-up, postoperative cylinder was between +0.50 and-0.50 D. in 31 eyes (67.4%); between-0.50 and-1.50 D. in 11 eyes (23.9%); between-1.50 and-2.50 D. in 4 eyes (8.7%). Mean post-operative cylinder was-1.21 D. (± 1. 70). Mean postoperative sphere was-1.09 D. (±1.25). Myopic and astigmatic improvement was achieved in each patient (100%). Topography analysis showed 69.4% were within 0.5 mm, 96.8% within 1 mm, 97.8% within 1.5 mm of centration; 55% of the patients achieved uncorrected visual acuity of 10/10 (Snellen). One patient (2.2%) lost one line of best corrected vision due to decentration and change of axis. Conclusion: These preliminary results of myopic astigmatic excimer laser PRK procedures compare favorably in efficiency and safety with reports of PRK for myopia.

Characteristics Influencing Outcomes of Excimer Laser Photorefractive Keratectomy

Ophthalmology, 1996

To identify preoperative and intraoperative characteristics associated with outcomes of photo refractive keratectomy (PRK). Methods: In the phase III multicenter clinical trials of the Summit Technology excimer laser for corrections of 1.5 to 6.0 diopters (0) of myopia, three principal outcomes of PRK on 612 patients were examined: (1) uncorrected visual acuity of 20/40 or better, (2) predictability of refractive outcome within 1.0 0 of attempted correction, and (3) stability of refractive result between 12 and 24 months. Multiple logistic regression was used to test for independent associations of multiple preoperative and intraoperative characteristics with each of these outcomes. Results: Older age was independently associated with lesser likelihood of achieving 20/40 or better uncorrected visual acuity (odds ratio = 1.08 per incremental year of age, 95% confidence interval [CI] = 1.04-1.12) and with decreased predictability, specifically with overcorrection (odds ratio = 1.09, 95% CI = 1.06-1.12), but age was not associated with stability of refraction. Greater attempted correction was associated independently with a decreased likelihood of 20/40 or better uncorrected visual acuity (odds ratio = 2.78 for corrections of 3.5-5.5 0, 95% CI = 1.18-6.75; odds ratio = 4.19 for corrections of :2::5.5 0 , 95% CI = 1.66-10.58), with decreased predictability (odds ratio = 1.72 for corrections of 3.5-5.5 0, 95% CI = 1.05-2.85; odds ratio = 2.95 for corrections of :2::5.5 0, 95% CI = 1.65-5.26), and with a reduced likelihood of stability of refraction (odds ratio = 3.46 for corrections of :2::5.0 0, 95% CI = 1.32-9.11). No intraoperative characteristics were associated with any of the outcomes assessed. Conclusions: Using this specific excimer laser system with an optical zone of 4.5 or 5.0 mm, patient age and attempted correction are important preoperative characteristics associated with postoperative uncorrected visual acuity and predictability of PRK. Stability of refraction is strongly associated with attempted correction. Such information may help guide patient selection, determine timing of fellow eye treatment, and suggest changes in the laser treatment algorithm for individual patients. Although these findings may be representative of PRK in general, similar analyses should be performed before modifying patient treatments using either a 6.0-mm treatment zone or other laser systems.

The Complications of Excimer Laser Photorefractive Keratectomy for Myopia in the First Year

European journal of Implant and Refractive Surgery, 1995

OBJECTIVE: To record the frequency and type of complications that occur following photorefractive keratectomy (PRK) for myopia. DESIGN: Prospective, with follow-up for 1 year. SETTING: Mater Private Hospital Laser Clinic, Dublin, Republic of Ireland. PATIENTS: One hundred and sixty one myopic eyes in 120 patients. MAIN OUTCOME MEASURES: Any complications occurring in the follow-up period. Patient satisfaction rating, on a graded scale, was recorded in the first 50 eyes in 50 consecutive patients at 1 year. RESULTS: Of 161 eyes 22.4% had early complications of their procedure. These were most commonly caused by the use of routine post-laser medications. Furthermore, only 6% of 50 patients surveyed, failed to achieve their original aim (wholely or in part) in undergoing the treatment. In no case was the visual outcome compromised by non-refractive complications. CONCLUSIONS: PRK is safer than extended wear soft contact lens use.