<s>[INST] context: * According to ETROP guidelines : * Stage 1, Zone 3: no Rx is required. STAGES : 1. Demarcation Line 2. Ridge 3. Fibrovascular Proliferation 4. Localized Retinal detachment 5. Total RD Plus Disease : 2 quadrants (usually 6 or more clock hours) of dilation and touosity of the posterior retinal blood vessels. ZONES : ZONE 1: take optic disc as centre, a circle is drawn with radius equal to twice the distance between fovea and optic disc ZONE 2: keep optic disc as centre draw a circle with double diameter as zone 1 with nasal ora serrata as nasal border. ZONE 3: it is the temporal crescent that is left Zone 1 and 2 are more dangerous zones Threshold Disease in ROP: -When stage 3 ROP is present in either zone I or zone II, with at least 5 continuous or 8 total clock hours of disease & presence of plus disease. NOT TO TREAT - Zone I, stage 1 or 2 with no plus disease or - Zone II, stage 3 with no plus disease - Zone III, stage 1 ROP THAT REQUIRES TREATMENT *Zone I, any stage ROP with plus disease or *Zone I, stage 3, with or without plus disease *Zone II, stage 2 or 3 ROP, with plus disease [/INST] question: Which of the following stage of ROP we can just wait and watch: | options: A: Aggressive posterior ROP B: Stage 4 ROP C: Stage 1, Zone 3 ROP D: Stage 2, Zone 1 with Plus disease | answer: C </s>