Abstract
Purpose: :
To determine the relationship of retinal vascular caliber with primary glaucoma in Asians.
Methods: :
This was a cross-sectional hospital-based study of 572 persons with primary glaucoma. All subjects underwent dilated digital retinal photography and standardized clinical assessment. Primary open angle glaucoma (POAG) patients with a mean untreated intraocular pressure (IOP) consistently less than 21 mm Hg on diurnal testing were classified as normal tension glaucoma (NTG), and those with higher IOP were classified as high tension glaucoma (HTG). Primary angle closure glaucoma (PACG) subjects had at least 180 degrees of angle closure on gonioscopy. Retinal vascular caliber was measured by computer-assisted software in a zone 0.5 to 1.0 disc diameter away from optic disc, and summarized as average retinal arteriolar and venular caliber of that eye. Left eye retinal vascular caliber was used for analyses.
Results: :
388 POAG subjects (195 HTG and 193 NTG subjects) and 184 PACG subjects were studied. While adjusting for age, gender, race and history of diabetes mellitus, hypertension and smoking, retinal venular caliber was narrowest in persons with NTG (207.02 µm, 95% CI 198.71, 215.32), followed by HTG (210.27µm, 95% CI 202.00, 226.72) and PACG (218.18 µm, 95% CI 209.65, 226.72) (p<0.001). Persons with NTG (odds ratio 1.74, 95% CI 1.36, 2.22, per standard deviation decrease in venular caliber) and HTG (odds ratio 1.41, 95% CI 1.12, 1.78) had narrower retinal venular caliber than persons with PACG. Retinal arteriolar caliber did not differ between glaucoma sub-types. In all subjects, narrower retinal arteriolar and venular caliber was associated with greater optic cup-disc ratio (p<0.001).
Conclusions: :
Eyes with POAG, particularly those with NTG, have narrower retinal venular caliber than PACG, suggesting a greater role for microvascular mechanisms in the pathogenesis of POAG and NTG. Assessment of retinal vascular caliber may provide insights into the role of vascular processes in different glaucoma subtypes.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • imaging/image analysis: clinical • pathobiology