Retinopathy of prematurity (ROP) is a developmental disease usually occurring in premature infants, particularly those weighing less than 1250 g at birth. Screening examinations to detect the presence and severity of ROP are time consuming and technically difficult. Most of the significant findings are present in the peripheral retina at the leading edge of retinal vascular development. Diagnosing neovascularisation in ROP requires the use of an indirect ophthalmoscope and scleral indentation in unstable infants who often reside in a glass encased isolette. Learning to diagnose and manage ROP is complicated enough that most who perform screening examinations are well trained in the intricacies and subtleties of this disease.

Screening examinations usually start 4–6 weeks after birth and continue at frequent intervals either until ROP progresses to threshold disease, with neovascularisation at the leading edge of developing retinal vasculature, when treatment should be applied with laser or cryoretinal ablation, or until it regresses spontaneously. In many cases this window of vulnerability to development of threshold ROP lasts several months. However, the timing of diagnosis of threshold disease is crucial, as it is well known that threshold disease may progress and worsen rapidly.

The stakes in screening for ROP are high. Almost 50% of eyes reaching threshold for treatment would suffer poor visual and anatomical outcome without …