Unilateral Refractive Keratotomy for Anisometropia

Excimer laser refractive correction of myopia after episcleral buckling for rhegmatogenous retinal detachment

PURPOSE

To evaluate the long-term effects of excimer laser treatment for ametropia after surgical treatment of rhegmatogenous retinal detachment (RRD) with scleral buckles.

SETTING

Helsinki University Eye Hospital, Helsinki, Finland.

METHODS

Ten patients (10 eyes) who had 1 or more surgeries for RRD followed by refractive surgery for myopia were retrospectively enrolled in this study and were examined after excimer laser refractive surgery. Photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) was performed using a Star S2 excimer laser system (Visx). The best spectacle-corrected visual acuity (BSCVA), refraction, degree of anisometropia, and topographical changes were evaluated before and after the surgeries.

RESULTS

All patients were free of asthenopic symptoms after refractive surgery. At the end of the follow-up, a mean of 67 months +/- 14 (SD) after refractive surgery, 6 patients were within +/-1.0 diopter of the intended correction. Compared with previously reported cohorts of myopic patients, the achieved refraction in patients who previously had a scleral buckling procedure was worse. The postoperative refraction was stable, and corneal topography did not show induced scar formation, keratectasia, or irregular astigmatism. After refractive surgery, the BSCVA improved 1 Snellen line in 3 patients and 2 lines in 1 patient. One patient lost 1 Snellen line and another patient lost 2 lines. Four patients showed no changes. New retinal complications were not observed.

CONCLUSIONS

In the long-term, PRK and LASIK were safe methods for the treatment of myopia in RRD patients after scleral buckling. The predictability of myopic LASIK/PRK may be worse than generally reported in myopic cohorts.

Improvement of Visual Acuity Following Refractive Surgery for Myopia and Myopic Anisometropia

PURPOSE

To test the hypothesis that anisometropic adults without significant amblyopia suffer from mild visual impairment probably due to aniseikonia, which might be improved by corneal refractive surgery.

METHODS

Fifty-seven patients presenting with myopic anisometropia > or = 3.25 diopters (D) and 174 myopic controls appropriate for refractive surgery were included. Photorefractive keratectomy (PRK) or LASIK was performed on 57 anisometropic eyes. As 43 of the 174 myopic control patients had bilateral surgery, PRK or LASIK was performed on 217 myopic control eyes. Best spectacle-corrected visual acuity (BSCVA), refraction, and refractive correction were measured preoperatively and at 1, 3, 5 to 7, 8 to 13, and 25 months following surgery.

RESULTS

Preoperative mean spherical equivalent was -7.20 +/- 2.40 D for anisometropic patients and -6.40 +/- 1.90 D for myopic patients. At 8 to 13 months postoperatively, when 23 (40%) anisometropic eyes and 94 (43%) myopic eyes were examined, the mean spherical equivalent refractions were -0.80 +/- 1.60 D and -0.30 +/- 0.60 D, respectively. Preoperatively, the mean BSCVA on a logMAR scale was -0.0143 +/- 0.0572 (Snellen 0.98 +/- 0.12) in the anisometropic group and 0.0136 +/- 0.0361 (Snellen 1.04 +/- 0.09) in the control group (P = .001). Eight to 13 months postoperatively, these values were 0.0076 +/- 0.0659 (Snellen 1.03 +/- 0.15) and 0.0495 +/- 0.0692 (Snellen 1.13 +/- 0.18) and this difference remained statistically significant (P = .012). For the myopic patients, the improvement in BSCVA reached almost maximum at 3 months, and this improvement was found to be highly significant 3 months after surgery (P = .001). The improvement in BSCVA was significantly slower for anisometropic patients and became statistically significant only after 8 to 13 months postoperatively (P = .041).

CONCLUSIONS

Anisometropia reduces visual acuity in the more myopic eye and can be at least partially reversed by refractive correction. The slower improvement in BSCVA for anisometropic patients suggests plastic changes in the visual cortex following refractive surgery.

Photorefractive Keratectomy for Visual Rehabilitation of Anisometropia Induced by Retinal Detachment Surgery

PURPOSE

To evaluate the efficacy of unilateral photorefractive keratectomy to correct anisometropia induced by retinal detachment surgery.

METHODS

Photorefractive keratectomy was performed in 10 eyes of 10 patients with anisometropia induced by previous retinal detachment surgery. The Aesculap Meditec MEL 60 excimer laser was used.

RESULTS

Preoperative mean spherical equivalent refraction was -5.20 D. Mean postoperative spherical equivalent refraction was -0.25 D after a mean follow-up of 12.9 months. Mean preoperative spherical equivalent refraction difference between two eyes of 4.87 D was decreased to a mean 0.60 D postoperatively (t-test, P < .0001). All patients were free of anisometropic symptoms after laser surgery.

CONCLUSION

Unilateral photorefractive keratectomy seems to be an effective method to correct anisometropia induced by conventional retinal detachment surgery, especially for patients with spectacle and contact lens intolerance.