Retinopathy of Prematurity.

Retinopathy of prematurity (ROP) primarily affects premature infants weighing about 2¾ pounds (1250 grams) or less that are born before 31 weeks of gestation.

IMMATURE RETINA AND ROP DIFFERENCE : Immature retina is incomplete retinal vessel development, but not ROP. The eye goes through a normal vessel development with retinal vessels grow from the optic nerve head towards the retinal periphery. If they grow normally, they reach the nasal retinal peiphery (ora seratta) by 36 weeks post conceptional age and temporal periphery by 40 weeks post conceptional age.
This is a stage of no retinopathy of prematurity. These vessels can grow normally or later get stopped to develop ROP.
STAGES OF ROP :
Stage 1 retinopathy of prematurity (ROP) signifies development of a demarcation line between the normal retinal vessel developed retina and avascualr retina, where vessels have not developed.
Stage 2 retinopathy of prematurity (ROP) signifies development of a demarcation ridge. The demarcation line of stage 1 gains height and width and extends above the retina surface.
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.
Stage 4 retinopathy of prematurity (ROP) signifies that retinal detachment has started to occur due to the traction of the fibrous and vascular tissue over the ridge. Its called 4A when the retinal detachment spares the macula, and stage 4B when retinal detachment involves the macula.
Stage 5  retinopathy of prematurity (ROP) signifies that total retinal detachment has occured. This is the last stage of retinopathy of prematurity, and the most severe stage too.
LASTLY, PLUS DISEASE.
Plus disease is characterized by abnormal dilation and tortuosity of the retinal arteries and veins at the posterior part of the retina of the eye. This signifies that the disease is active and might progress. Plus disease also causes iris rigidity causing the difficult pupil dilation. Decrease is plus disease is a good sign and might herald disease regression..
Courtesy- Rop.com.
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