A comparison of dense versus less dense diode laser photocoagulation patterns for threshold retinopathy of prematurity

Abstract

Objective: To determine if the density of diode laser photocoagulation for the treatment of zone 1 or zone 2 threshold retinopathy of prematurity (ROP) affects the rate of progression of the disease.

Design: Retrospective, nonrandomized, comparative trial (n = 12) and prospective, randomized, clinical trial (n = 46).

Participants: Two surgeons treated a total of 107 eyes from 58 patients with zone 1 or zone 2 threshold ROP within 72 hours of diagnosis. The two consecutive groups of patients were treated with two different diode laser photocoagulation patterns between May 1995 and October 1997 and were observed for at least 3 months.

Intervention: All patients underwent diode laser photocoagulation of the peripheral avascular retina extending from the ridge of extraretinal proliferation to the ora serrata. One cohort received a near confluent laser pattern, whereas the second cohort received a pattern of laser spots placed 1 to 1.5 burn widths apart.

Main outcome measures: Anatomic outcome, rate of progression to stage 4 or 5 retinopathy of prematurity, postoperative complications, and timing and frequency of retreatment.

Results: For analysis, the retrospective and randomized outcome data were grouped. The rate of progression in the near confluent laser treatment group was 3.6% overall, 0% of zone 1 eyes, and 3.8% of zone 2 eyes. The rate of progression in the less dense treatment group was 29% overall, 44% of zone 1 eyes, and 21 % of zone 2 eyes. Mean time to retreatment was 16 days in cohort 1 and 24 days in cohort 2.

Conclusions: A dense pattern of diode laser treatment for threshold ROP and prompt retreatment for residual plus disease significantly reduce the rate of progression in eyes with zone 2 disease (P = 0.02) and may be beneficial in eyes with zone 1 disease.