Stage 3 retinopathy of prematurity (ROP) signifies development of a new vessels (neovascularization) in the stage 2 demarcation line and leads to extraretinal proliferation of tissue. The ridge may now bleed and cause traction on the ridge.
Stage three is a critical stage in development of ROP as it signifies that retinal ischaemia is significant enough to cause development of new vessels in an attempt to supply oxygen to this retina. However since retinal vessels are not there in the avascular retina in the periphery, the new vessels grow in a futile attempt to try to re-vascularise the area.
Extensive development of new vessels causes them to grow into the vitreous gel in the middle of the eye, which incites fibrous proliferation which eventually causes traction over the Ridge and can lead to retinal detachment. Extensive stage three ROP progresses through stages of prethreshold ROP to threshold ROP.
Development of stage three is critical for analysis of type I ROP, which is the current guidelines for treatment. Laser treatment can effectively reduce the development and progression of new vessels in the retina and can lead to regression of the disease.
It is very important for retinal specialists to identify and treat the disease as early as possible to prevent further complications.