Refractive outcome of prethreshold retinopathy of prematurity treated by diode laser: follow-up at 5 years

Abstract

Phuoc Huu Nguyen,1,2 Caroline Catt,2 Tinh Xuan Nguyen,3 Van Trong Pham4,51Department of Ophthalmology, Thanhhoa Paediatrics Hospital, Thanhhoa City, Vietnam; 2Save Sight Institute and Discipline of Clinical Ophthalmology, University of Sydney, NSW, Australia; 3Paediatrics Department, Vietnam National Ínstitute of Ophthalmology, 4Ophthalmology Department, Hanoi Medical University, 5Oculoplastics and Cosmesis Department, Vietnam National Ínstitute of Ophthalmology, Hanoi, VietnamBackground: The purpose of this study was to evaluate the refraction of eyes treated with diode laser photocoagulation for prethreshold retinopathy of prematurity (ROP) at a mean of 5 years after treatment.Materials and methods: Fifty infants with prethreshold ROP treated with diode laser at Hanoi Childrens’ Hospital during the period 2008 to 2009 were reviewed. Refractive error was identified by cycloplegic refraction with Cyclogyl 1%. Myopia was divided into two categories based on magnitude: high myopia (more than -5.00 D) and low myopia (between 0 and -5.00 D). Hypermetropia was subdivided into low hypermetropia (between 0 and +5.00 D) and high hypermetropia (greater than +5.00 D). Astigmatism was classified as high if >2.00 D. Eyes with media opacification that interferes with retinoscopy were excluded. The refractive outcome was correlated with birth weight and gestational age. The anatomical and visual outcomes were recorded.Results: One hundred eyes from 50 infants were included in the study. The mean birth weight was 1,426.4 g and the mean gestational age was 29.88 weeks. After 5 years of follow-up, the average spherical equivalent for 100 eyes was -2.87 D. On cycloplegic retinoscopy, high myopia (more than -5.00 D) was seen in 32% of eyes. Twenty (20%) eyes had nonsignificant hypermetropia, and high hypermetropia (more +5.00 D) was seen in only one eye (1%). The prevalence of astigmatism and high astigmatism (more than -2.00 D) was 79% and 49%, respectively. Three infants (6%) had esotropia and two infants (4%) had exotropia. None of the infants had nystagmus.Conclusion: The majority of patients who underwent diode laser therapy for prethreshold ROP had favourable anatomical and visual outcomes. High refractive error is common and may be the cause of visual impairment.Keywords: refractive outcome, myopia, hypermetropia, astigmatism