Which element is NOT part of the standard classifications for retinopathy of prematurity?

• A. Stages
• B. Color of retina
• C. Zones
• D. Clock hours

Answer: (B)

Retinopathy of prematurity is categorized by where and how severely the retina is affected, using stages, zones, and clock hours. The color of the retina is not part of this standard classification.

Stages describe the progression from an initial demarcation between vascularized and avascular retina (stage 1) through increasing levels of plus disease and retinal detachment (up to stage 5). Zones map the location of the disease relative to the optic nerve, with posterior Zone I being closest to the nerve and fovea, then Zone II and Zone III extending outward. Clock hours quantify the extent of involvement within the affected zones on a clock-face map, indicating how many hours of the retina show disease involvement. Plus disease (dilated and tortuous posterior vessels) is a severity modifier that influences treatment decisions but remains within the standard framework.

Color of the retina, while observable in examination, does not constitute a classification criterion in this system.