Abstract
Purpose: :
Fluorescein angiographic measurements allow assessment of retinal perfusion. Correlations of depressed static contrast sensitivity with increasing capillary drop out in diabetic maculopathy have been demonstrated. Prolonged arteriovenous passage (AVP) times are coupled with more severe visual field damage in asymmetric glaucoma. This analysis was performed to test whether there is a correlation of AVP and static contrast sensitivity in glaucoma patients.
Methods: :
Digital scanning laser fluorescein angiography (Scanning Laser Ophthalmocsope (Rodenstock Instr., Germany) 25 Hz) was performed to assess retinal AVP times that represent the passage of dye through a retinal vascular segment from artery passing through capillary formation and into the vein. Static contrast sensitivity results were obtained using the CSV–1000 (Vector Vision; Dayton, OH, USA) with 4 spatial frequencies (3,6,12,18 cycles per degree (cpd)). Eighty five subjects were included in this analysis (healthy subjects: n=22; glaucoma like disk: n=10; ocular hypertensive patients: n=13; normal pressure glaucoma (NPG): n=33; primary open angle glaucoma (POAG): n=7).
Results: :
Anova testing revealed significant differences between groups (p=0.0008 AVP; p<0.0001, 3,6,12,18 cpd). Contrast sensitivity at all four spatial frequencies were inversely correlated with arteriovenous passage times (3 cpd/AVP: r=–0.47, p<0.0001; 6 cpd/AVP: r=–0.46, p<0.0001; 12 cpd/AVP: r=–0.44, p<0.0001; 18 cpd/AVP:r=–0.4, p<0.0001). Correlation subgroup analysis showed no significant correlation of AVP and contrast sensitivity for healthy subjects, patients with glaucoma like disk, or ocular hypertension. In NPG AVP was correlated with contrast sensitivity at 3,6 &12 cpd (p=0.0008, 3cpd; p=0.0006, 6 cpd; p=0.03, 12 cpd), whereas POAG patients reached only borderline significance due to the small sample size.
Conclusions: :
Glaucomatous optic neuropathy representing a multi–factorial disease is associated with a circulatory mal–perfusion of the optic disk and retina. Functional damage measured by static contrast sensitivity at all spatial frequencies occurred and was found to be correlated with more prolonged retinal circulation. The study suggests a relationship of retinal circulatory alterations and functional loss of contrast sensitivity in NPG patients.
Keywords: contrast sensitivity • blood supply • imaging/image analysis: clinical