Retinopathy of Prematurity
Xi Chen, MD, PhD
Lejla Vajzovic, MD
Cynthia A. Toth, MD
Preterm infants are at risk for retinopathy of prematurity (ROP), a disease caused by delayed or pathological retinal vascular growth. Left untreated, ROP could lead to fibrosis, retinal detachment, and blindness. With improvement in neonatal medicine and increased survival of very preterm infants, ROP severity has increased and become more prevalent.
Screening guidelines (United States): Infants with a birth weight of 1500 g or less or a gestational age of 30 weeks or less, and selected infants with a gestational age of more than 30 weeks or a birth weight between 1500 and 2000 g who are believed to be at risk for ROP. Screening is performed starting at 4 weeks after birth or at 31 weeks postmenstrual age (whichever is later). Standard screening is performed by an ophthalmologist using eyelid speculum, topical anesthesia, scleral depressor, and indirect ophthalmoscopy with a 28-diopter lens.
ROP classification (defined by International Classification of Retinopathy of Prematurity [ICROP]1): ROP is described as zone, stage, and vascular activity (plus disease) (Fig. 28.1).
Zone I: circle with radius of twice the distance between fovea and optic nerve centered at the optic nerve.
Zone II: radius of the distance between the nasal ora in the horizontal meridian centered at the optic nerve.
Zone III: the remaining retina.
Stage 1: narrow white line at the vascular-avascular junction.
Stage 2: ridge of thickening at the vascular-avascular junction.
Stage 3: neovascularization with growth of vessels toward the vitreous cavity.
Stage 4: partial retinal detachment not involving (4A) or involving the fovea (4B).
Stage 5: total retinal detachment.
Plus disease: two or more quadrants of dilated and tortuous vessels at the posterior pole.
Aggressive posterior ROP: Posterior severe plus disease, with the absence of obvious neovascular elevations but marked circumferential shunt vessels and flat neovascularization (sometimes presumed). These eyes have a high degree of vascular activity and therefore carry a higher risk of progression to retinal detachment.
Isolated neovascular tufts (“popcorn”)2: Small isolated tufts of neovascular tissue, often observed posterior to stage 2 ridge, are believed to increase the risk of progression to stage 3 disease.
IMAGING IN ROP
Indirect ophthalmoscopy is the gold standard for ROP diagnosis. The goal of telemedical screening for ROP is to identify referral-warranted ROP3 (defined as any ROP in zone I, plus disease, or stage 3 ROP). Imaging in infants at risk for ROP helps to document and evaluate ROP and serves as a vehicle for telemedical screening.