Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is the main reason of preventable blindness in pediatric age group. In this disease, incomplete development of retinal vessels in a premature neonate cause retinal ischemia and formation of retinal new vessel, which can result in retinal detachment and vision loss. Early diagnosis and intervention can prevent blindness; therefore, timely screening should be highlighted in these infants. The most important risk factors for developing ROP in a premature infant are low birth weight and low gestational age. Other possible predisposing elements are genetic, supplementary oxygen and variations in blood oxygen level, blood transfusion, sepsisو and blood glucose level. In developed countries, chances of ROP causing blindness is less than 10%, whereas this proportion is up to 40% in developing countries due to limitations in resources, neonatal care and NICU facilities, and availability of retinal exam. Therefore, it is recommended that screening guidelines be customized in each country. Based on a research conducted at Farabi eye Hospital in Tehran, 2016, screening guidelines in Iran has been defined as gestational age £32 weeks and gestational weight £2000 gram. Following this guideline, infants need treatment can be identified with a sensitivity of about 100%, while unnecessary exams will be at its lowest rate. Using screening recommendations of American Academy of Pediatrics would miss 8.4% ROP requiring treatment in this cohort. The first retinal examination of premature infants with gestational age of £27 weeks should be at 31st week of postmenstrual age. This time for neonates with gestational age of 28-32 weeks is at 4-6 weeks after birth or postmenstrual age of 31-33 weeks (whichever is later). An international committee of ROP classified retina (with the centration of optic nerve) into 3 zones (I-III) and categorized severity of ROP into 5 stages (1-5). Plus disease, which is defined as vascular dilation and tortuosity in posterior pole, shows severity of disease and it is an indication for treatment. Guidelines for examination follow up and treatment is based on this international classification. 90% of ROP spontaneously regress in stage 1 and 2. Of those with aggressive posterior ROP, approximately 17% progress to retinal detachment. The gold standard of treatment of ROP is laser, which ablates avascular retina and helps control the activity of disease and regression of new vessels. Intravitreal injections of anti VEGF (Bevacizumab) has been recently considered the treatment of choice for treatment of zone I ROP. Although the regression time is shorter in the injection group, these babies require a longer follow-up time for the retina to become fully vascularized and should be monitored for the possible complications may occur in avascular retina. Recurrence showed to be more common in posterior zone II cases. Fluorescein angiography can be helpful in suspicious cases of recurrence due to its potential in differentiating new vessels from shunt vessels. Scleral buckling and vitrectomy are treatment options when there is a retinal detachment. Overall, children with ROP need a long life follow-up for managing the possible complications, of which the most devastating are retinal detachment and glaucoma.