A comparison of laser photocoagulation with cryotherapy for threshold retinopathy of prematurity at 10 years ☆: part 1. Visual function and structural outcome1

Abstract Objective To assess visual and structural outcomes after laser photocoagulation and transscleral cryotherapy for threshold retinopathy of prematurity (ROP) after 10 years. Design Extended follow-up of a randomized controlled clinical trial. Participants One hundred eighteen eyes from 66 patients were randomly assigned to receive either cryotherapy or laser photocoagulation for threshold ROP. Forty-four eyes from 25 patients were examined for 10-year follow-up evaluations. Intervention Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity, slit-lamp, and fundus examination; fundus photography; and B-scans (eyes with retinal detachments) were performed. Patients' histories were taken to elicit past amblyopia therapy. Based on fundus photographs, independent observers graded the degree of retinal dragging as none, mild, moderate, or severe. Main and secondary outcome measures Best-corrected ETDRS visual acuity (BCVA). The degree of dragging was determined clinically and photographically. In addition, the presence of strabismus or amblyopia and/or any history of treatment for amblyopia were noted accordingly. Results Eyes treated with laser had a mean BCVA of 20/66 (Snellen equivalent), whereas cryotherapy-treated eyes had a mean BCVA of 20/182 (Snellen equivalent) ( P = 0.015, n=42). Compared with eyes treated with cryotherapy, eyes treated with laser photocoagulation were 5.2 times more likely to have a 20/50 or better BCVA (95% confidence interval, 1.37–19.8, n=42). Eyes treated with cryotherapy were 7.2 times (95% confidence interval, 1.54–33.6, n=33) more likely to develop retinal dragging compared with laser treatment. By linear regression analysis, ETDRS visual acuity was inversely proportionate to the degree of retinal dragging in both laser ( r = −0.637, P = 0.006) and cryotherapy ( r = −0.517, P = 0.040) treated eyes. Among the 21 patients with favorable outcomes in both eyes, 13 had strabismus (62%) and 6 had received amblyopia therapy (29%). Ptosis, loss of cilia, and cortical cataract were among probable treatment-related complications that were noted in this study. Conclusions Overall, laser-treated eyes had better structural and functional outcome compared with eyes treated with cryotherapy.