In retinopathy of prematurity, plus disease is defined by which vascular changes?

• A. Extraretinal neovascularization
• B. Stage 5
• C. Stage 3
• D. Plus disease

Answer: (D)

Plus disease is defined by dilation and tortuosity of the posterior retinal vessels, especially in the posterior pole near the optic disc. This vascular pattern signals more active and aggressive retinopathy of prematurity and often prompts urgent treatment. The other options describe structural stages or features of ROP (such as extraretinal neovascularization or retinal detachment) rather than the specific vascular changes that define plus disease.