Retinopathy of Prematurity - Pathophysiology

Pathophysiology

Normally, maturation of the retina proceeds in-utero, and at term the mature infant has fully vascularized retina. However, in preterm infants, the retina is often not fully vascularized. ROP occurs when the development of the retinal vasculature is arrested and then proceeds abnormally. The key disease element is fibrovascular proliferation. This is growth of abnormal new vessels that 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". Supplemental oxygen exposure, while a risk factor, is not the main risk factor for development of this disease. Restricting supplemental oxygen use does not necessarily reduce the rate of ROP, and may raise the risk of other hypoxia-related systemic complications.

Other physicians have suggested that supplemental oxygen, specifically oxygen tents given to pre-term infants specifically causes ROP. The hypothesized mechanism involves the degradation and developmental cessation of blood vessels in the presence of excess oxygen. When the excess oxygen environment is removed, the blood vessels begin forming rapidly again and grow into the vitreous humor of the eye from the retina, sometimes leading to blindness. This does not preclude the dangers of hypoxic environments for premature infants.

Patients with ROP are at greater risk for strabismus, glaucoma, cataracts and myopia later in life and should be examined yearly to help prevent and treat these conditions.