Ocular Neovascularization

Induction by fibroblast growth factors of mesoderm during gastrulation leads to blood-forming tissue, including angioblasts and hemopoietic cells, that together constitute the blood islands of the yolk sac. The differentiation of angioblasts from mesoderm and the formation of primitive blood vessels from angioblasts at or near the site of their origin are the two distinct steps during the onset of vascularization that are defined as vasculogenesis. Vascular endothelial growth factor and its high-affinity receptor tyrosine kinase flk-1 represent a paracrine signaling system crucial for the differentiation of endothelial cells and the development of the vascular system. Specified cell adhesion molecules such as VE-cadherin and PECAM-1 (CD-31), and transcription factors such as ets-1, as well as mechanical forces and vascular regression and remodeling are involved in the subsequent events of endothelial cell differentiation, apoptosis, and angiogenesis.

To determine the prevalence of age-related maculopathy in an elderly population in The Netherlands. Fundus photographs of 6251 participants of the Rotterdam Study, a single-center prospective follow-up study in persons 55 to 98 years of age, were reviewed for the presence of drusen, pigmentary abnormalities, and atrophic or neovascular age-related macular degeneration. The prevalence of at least one drusen of 63 microns or larger increased from 40.8% in persons 55 to 64 years of age to 52.6% in those 85 years of age or older. Similarly, the prevalence of the following abnormalities increased significantly in these age categories: drusen of 125 microns or larger from 4.8% to 17.5%, retinal pigment epithelial hypopigmentations from 3.5% to 9.0%, and increased retinal pigment from 3.7% to 15.3%. Atrophic or neovascular age-related macular degeneration was present in 1.7% of the total population. Atrophic age-related macular degeneration increased from 0.1% in persons 55 to 64 years of age to 3.7% in those 85 years of age or older. Neovascular age-related macular degeneration increased from 0.1% to 7.4% in these age groups. No sex differences were observed for these lesions. The prevalence of atrophic or neovascular age-related macular degeneration is 1.7%. In those 55 years of age or older, the prevalence increases strongly with age and it is similar in men and women. Neovascular age-related macular degeneration was twice as common as atrophic age-related macular degeneration. These findings suggest that age-related maculopathy may be less common in this European population than in similar populations in the United States.

Bilateral blindness unrelated to simple refractive error is twice as prevalent among blacks as among whites, although the difference narrows among the elderly. The reasons for this race- and age-related pattern are uncertain. A randomly selected, stratified, multistage cluster sample of 2395 blacks and 2913 whites 40 years of age and older in East Baltimore underwent detailed ophthalmic examinations by a single team. We identified 64 subjects who were blind in both eyes. The leading causes of blindness were unoperated senile cataract (accounting for blindness in 27 of the total of 128 eyes), primary open-angle glaucoma (17 eyes), and age-related macular degeneration (16 eyes). Together, these three disorders accounted for 47 percent of all blindness in this sample. Unoperated cataract accounted for 27 percent of all blindness among blacks, among whom it was four times more common than among whites; whites were almost 50 percent more likely than blacks to have undergone cataract extraction before the age of 80 (P less than 0.002). Primary open-angle glaucoma accounted for 19 percent of all blindness among blacks; it was six times as frequent among blacks as among whites and began 10 years earlier, on average. By contrast, age-related macular degeneration resulting in blindness was limited to whites, among whom it was the leading cause of blindness (prevalence, 2.7 per 1000; 95 percent confidence interval, 1.2 to 5.4); it affected 3 percent of all white subjects 80 years of age or older. The pattern of blindness in urban Baltimore appears to be different among blacks and whites. Whites are far more likely to have age-related macular degeneration, and blacks to have primary open-angle glaucoma. The high rate of unoperated cataracts among younger blacks and among elderly subjects of both races suggests that health services are underused. Half of all blindness in this urban population is probably preventable or reversible.