During development, blood vessels grow from the central part of the retina outwards. This process is completed a few weeks before the normal time of delivery. However, in premature babies it is incomplete. If blood vessels grow normally, ROP does not occur. If the vessels grow and branch abnormally the baby develops ROP.
These abnormal blood vessels may grow up from the plane of the retina and may bleed inside the eye. When the blood and abnormal vessels are reabsorbed, it may give rise to multiple band like membranes which can pull up the retina, causing detachment of the retina and eventually blindness before 6 months.
Normally, maturation of the retina proceeds in-utero, and at term, the medial portion of the retina is fully vascularized, while the lateral portion is only incompletely vascularized. The normal growth of the blood vessels is directed to relatively low-oxygen areas of the retina, but the vessels remain in the plane of the retina and do not grow into the vitreous humor. If excess oxygen is given, normal blood vessels degrade and cease to develop. When the excess oxygen environment is removed, the blood vessels rapidly begin forming again and grow into the vitreous humor of the eye from the retina.
The key disease element in ROP is fibrovascular proliferation. This is growth of abnormal new vessels; this may regress, but frequently progresses. Associated with the growth of these new vessels is fibrous tissue (scar tissue) that may contract to cause retinal detachment. Multiple factors can determine whether the disease progresses, including overall health, birth weight, the stage of ROP at initial diagnosis, and the presence or absence of “plus disease”.
Babies are examined by doctors at Southern Vitreoretinal Associates starting at 6 weeks after birth.
If a baby is determined to have “threshold” disease then laser treatment is considered. Treatment of laser by doctors at Southern Vitreoretinal Associates in the hospital to the area of non-perfused retina can help prevent retinal detachments.
Supplemental oxygen exposure, while a risk factor, is not the main risk factor for development of this disease. Restricting supplemental oxygen use reduces the rate of ROP, but may raise the risk of other hypoxia-related systemic complications, including death.
Patients with ROP, particularly those who have developed severe disease needing treatment are at greater risk for retinal detachment, strabismus, glaucoma, cataracts, and shortsightedness (myopia) later in life and should be examined yearly to help prevent or detect and treat these conditions.