Retinopathy of prematurity stages

Retinopathy of prematurity stages or ROP is retinal disease seen in prematurely born or babies with low birth weight. Babies born with less than 1.500g (1.5kg) or before 32 weeks are exposed to greater risk to develop ROP. There are three zones (1, 2 and 3) and six stages of this vision problem (known as stages 0, 1, 2, 3, 4 and 5).

Stage 0 of ROP

Retinopathy categorized as stage 0 is mildest form of this condition, caused by immature vasculature and without clear demarcation of vascularized and non-vascularized retina. In zone 1 stage 0 ROP is seen as vitreous haze and this should be examined every week. Zone 2 should be examined every 2 weeks, while zone 3 should be examined every 3 to 4 weeks.

Stage 1

In these patients doctors usually notice thin demarcation line separating vascular and avascular region. There is no thickness or height of this line. In zone 1 this is flat, thin line, without elevation for avascular part of retina. Similarly like in stage 0, zone 1 should be examined every week, zone 2 bimonthly and zone 3 every couple of weeks.

Stage 2

From the avascular part of retina there is visible, broad and thick ridge which separates this structure and vascular retina. If there is some pinkness or redness of the ridge in zone 1, this is not a good sign. If there are some engorged blood vessels present, this requires proper treatment in next three days. Without vascular changes in zone 2, eye examinations are recommended every 2 weeks. Zone 3 should also be examined every 2 to 3 weeks, if there are no vascular problems.

Stage 3

On the ridge, there might be some extraretinal proliferation of fibrovascular tissue and this process is known as neovascularization. Because of this, the ridge looks velvety and have ragged border. Neovascularization in zone 1 is serious problem and it must be treated. If there are no vascular tortuosity or straightening of the vascular arcades, examination every 2 to 3 weeks is found to be sufficient.

Stage 4

In stage 4 of retinopathy of prematurity there is some subtotal detachment of the retina which starts at the ridge. This fibrovascular ridge pulls retina into the vitreous. This condition is classified as 4A when it doesn’t involve fovea or 4B when the fovea is involved.

Stage 5

Retina in stage 5 has been completely detached and it possesses the shape of a funnel. It can look either like open funnel (which is known as stage 5A) or closed funnel (stage 5B).