To compare measurements of the foveolar choroidal blood circulation in subjects with nonexudative, age-related macular degeneration (AMD) with those of control subjects.
Laser Doppler flowmetry was ...used to assess relative choroidal blood velocity (ChBVel), volume (ChBVol), and flow (ChBFlow) in the center of the fovea. Measurements were obtained in 20 eyes of 20 subjects with 10 or more large drusen, visual acuity of 20/32 or better, and no evidence of choroidal neovascularization. Findings obtained in these subjects were compared with those of 10 eyes of 10 age- and blood pressure-matched control subjects with no large drusen. Foveolar choroidal blood flow measurements were obtained by asking the study participants to fixate on a probing laser beam.
No significant differences in average age, blood pressure, or intraocular pressure were observed between subjects with AMD and control subjects. In subjects with AMD, average ChBVol was 0.24 +/- 0.08 (+/- 1 SD) arbitrary units (AU); this value was 33% lower than that of control subjects (0.36 +/- 0.11 AU; two-tailed, independent Student's t-test, P = 0.005). Average ChBVel, conversely, was not significantly different from normal (0.44 +/- 0.07 AU) in subjects with AMD (0.44 +/- 0.10 AU). Average ChBFlow in subjects with AMD (8.7 +/- 3.1 AU) was 37% lower than that of control subjects (13.7 +/- 3.5 AU) (P = 0.0005). Average blood flow pulsatility was 6% higher in subjects with AMD (0.71 +/- 0.15) than in control subjects (0.66 +/- 0.14), but this difference was not statistically significant (P = 0.42).
Average ChBFlow in the nonexudative stages of AMD is lower than that of age-matched controls, and the effect is caused mainly by a decrease in ChBVol. Further studies are needed to elucidate whether decreased ChBFlow plays a role in the development of choroidal neovascularization, and whether ChBFlow measurements may help identify subjects with AMD at risk for developing choroidal neovascularization.
Choroidal neovascular membranes (CNVMs) developed in eight patients after photocoagulation for clinically significant diabetic macular edema (DME). The CNVMs developed in areas where Bruch's membrane ...was ruptured and were diagnosed 2 weeks to 5 months after treatment. Only six patients had symptoms. The CNVMs were treated in four patients; final visual acuity was poor in all eight patients. This serious complication that follows laser treatment for DME may be related to the use of repeated small-size, short-duration laser or intense laser burns, or both.
In 14 of 27 eyes with choroidal neovascular membranes associated with severe myopia, visual acuity deteriorated two or more lines on the Snellen chart. Twelve of the 27 eyes became legally blind. ...Final visual acuity may be related to the position of the neovascular membrane within the posterior pole. Four of the eight eyes with new vessels outside of the foveal avascular zone had follow-up visual acuities of 6/12 (20/40) or better. Only one of five eyes with new vessels extending to the edge of the avascular zone had a final visual acuity of 6/12 (20/40) or better. Three of 14 eyes with a neovascular membrane beneath the foveal avascular zone had visual acuities of 6/12 (20/40) or better. Neovascularization associated with severe myopia clearly jeopardizes central visual acuity. Laser photocoagulation therapy may be useful in treating neovascular membranes outside the foveal avascular zone or extending to the edge of the perifoveal capillary network. A larger prospective study is needed to determine the guidelines for and efficacy of such treatment for patients with severe myopia who develop choroidal neovascularization.
To explore morphological and vision changes in untreated eyes with subfoveal choroidal neovascularization (CNV) that have poorly demarcated boundaries.
Analysis of photographs of untreated patients ...with poorly demarcated occult CNV participating in a prospective clinical trial evaluating laser treatment compared with observation.
Two tertiary retinal referral centers.
Symptomatic individuals with poorly demarcated subfoveal occult CNV associated with age-related macular degeneration.
Change in size of lesion, development of classic CNV, change in vision, and development of subretinal fibrosis.
During follow-up (9-12 months), 32% of the occult choroidal neovascular lesions more than doubled their original size. Classic CNV developed in 52% of eyes that started without it. The median loss in visual acuity was 2.5 lines. Eyes with classic CNV or subretinal blood or both at baseline developed subretinal fibrosis more frequently and lost more visual acuity, but not to a statistically significant degree.
The morphological changes of eyes with subfoveal occult CNV in which the boundaries are poorly demarcated in variable; the presence of subretinal blood or a component of classic CNV may influence the prognosis for further loss of vision.
Age-related macular degeneration Bressler, N M; Bressler, S B; Fine, S L
Survey of ophthalmology,
05/1988, Letnik:
32, Številka:
6
Journal Article
Recenzirano
Age-related macular degeneration (AMD) is the leading cause of irreversible severe visual loss in the United States in people over 50 years of age. The nonexudative stage includes hard drusen ...(associated with localized dysfunction of the retinal pigment epithelium RPE), soft drusen (associated with diffuse dysfunction of the RPE), and geographic (areolar) atrophy. These fundus changes may predispose the eye to develop the neovascular/exudative stages of AMD. Most patients who develop severe visual loss from AMD have this exudative stage. Treatment for AMD has been shown to be effective for only a small proportion of patients who have a well-defined choroidal neovascular membrane (CNVM) more than 200 microns from the foveal center. Even in successfully treated cases, severe visual loss is postponed only for about 18 months because of the high rate of recurrent CNVMs that extend into the fovea. Thus, despite recent breakthroughs in laser treatment for AMD, most patients who develop the exudative form of AMD will develop central visual impairment. At the present time, the only available treatments for the majority of patients who develop the exudative form of AMD are low vision aids. Investigators are currently evaluating whether treatment is effective for membranes within 200 microns of the foveal center. Future studies need to be directed toward further understanding of the pathogenesis, treatment and prevention of the blinding complications of AMD.
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