Visual and refractive outcome after 12 years of treatment of type 1 prethreshold retinopathy of prematurity

Abstract

Aim: In this study, the best corrected visual acuity (BCVA) and refraction in preterm-born infants in South-Eastern Bulgaria after 12 years of treatment for type 1 prethreshold retinopathy of prematurity were presented, and the outcomes of laser treatment and cryotherapy were compared. Materials and methods: Since 2010, we have treated 319 eyes of 164 prematurely born children for type 1 prethreshold retinopathy of prematurity and were prospectively followed up. The mean (range) gestational age was 28.6 weeks of gestation (23–33) and the mean (range) birth weight was 1143 g (570–1990). Cryotherapy was applied on 76 eyes (23.2%), laser was used in 215 eyes (65.5%), anti-VEGF – in 10 eyes (3%) and surgery – in 18 eyes (5.5%). Twelve children (24 eyes, 7.3%) were lost to the follow-up. BCVA was tested in 114 eyes and refraction in 190 eyes. Because of the small number of eyes treated surgically or with anti-VEGF (18 and 10, respectively), these children’s eyes were excluded from the statistical analysis. Results: Fifty eyes showed BCVA between 0.6 and 1.0; 25 eyes – between 0.2 and 0.5; 5 eyes – between 0.04 and 0.1; 5 eyes between light perception –0.03 and 4 eyes were totally blind. Laser-treated eyes showed statistically significantly higher BCVA compared to the cryotherapy treated eyes (Fisher’s exact test, p=0.012). Myopia (any myopic refraction) was found in 50 eyes; hyperopia (>+2 D) – in 20 eyes; astigmatism (difference between the two principal meridians >0.75 D) – in 70 eyes, and emmetropia – in 30 eyes. Although in the laser-treated group more eyes showed emmetropic and hyperopic refraction compared to cryo treated group (25 eyes vs. 7 eyes – emmetropia and 15 eyes vs. 5 eyes – hyperopia, respectively), the difference did not reach statistical significance (Fisher’s exact test, p=0.106). Conclusion: Timely treatment of type 1 prethreshold retinopathy of prematurity leads to very good anatomical and functional results. Laser treatment leads to significantly higher BCVA, compared to cryotherapy. Emmetropia and hyperopia are more commonly seen in laser-treated eyes.