The effect of laser frequency on the outcomes of treatment of Type 1 Retinopathy of Prematurity: ND YAG laser (532nm) vs Diode laser (810nm).

Abstract

Purpose : To compare the structural and refractive outcomes in eyes treated for Type 1 retinopathy of prematurity (ROP) with the ND-YAG (532nm) and diode (810nm) retinal laser photocoagulation.

Methods : Retrospective chart review of babies diagnosed with Type 1 ROP and treated with retinal laser photocoagulation between January 1st 2006 and December 31st 2021. The charts of babies with complete documentation of ROP treatment and >1 cycloplegic refraction were included in the study. Eyes with ocular and systemic risk factors for refractive abnormalities were excluded. To account for the multiple measurements within each subject, the association between laser frequency and refractive outcomes were assessed using penalized quasi-likelihood method within the framework of generalized mixed effects model. A two-sided p-value of 0.05 was used to determine statistical significance.

Results : The charts of ninety-eight babies (193 eyes) who met the study’s inclusion criteria were reviewed. One hundred and sixty-three eyes received treatment with the diode laser and 30 eyes, ND-YAG laser. The average age at initial laser therapy was 36.4 weeks in the diode laser group and 44.5 weeks in the ND-YAG treatment group (p < 0.001). 77% of eyes treated with the ND-YAG laser received intravitreal bevacizumab injection prior to laser therapy, compared with 6% of eyes treated with the diode laser (p<0.001) however the diode laser treated eyes received more laser spots (p<0.001) and utilized more power (<0.001). The laser-retreatment rate was similar in both groups (p=0.7). Neither group had any significant structural complication attributed to treatment and the most frequent long-term ocular morbidity was esotropia. The generalized mixed effect model showed no significant difference in the refractive outcomes over time between the two types of laser treatment groups (p = 0.5). On regression analysis, the determinants of refractive outcome were gestational age at birth, age at diagnosis of type 1 ROP and birthweight (p < 0.05).

Conclusions : This study did not show any difference in refractive and structural outcomes between eyes treated with diode (810nm) and ND-YAG (532nm) laser. Further longitudinal studies will be required to establish these findings.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.