Iris transillumination defects in patients with primary open angle glaucoma.

PURPOSE: To examine the incidence and pattern of iris transillumination defects in patients with primary open angle glaucoma (POAG) with and without vascular dysregulation, in comparison to controls. METHODS: We prospectively examined 24 patients with POAG (M/F 10:14; mean age 59 +/- 14, range 21-76 years) and 23 controls (M/F 10:13; mean age 52 +/- 15, range 25-86 years). Vascular dysregulation was presumed if patients had a typical medical history of vasospasm and a pathological result in nailfold capillaroscopy. Iris transillumination defects were visualized by video-taped, digitized diaphanoscopy and assessed by two blinded observers. RESULTS: We found significantly more iris transillumination defects in POAG than in controls (54.2% vs. 8.7%; chi2 = 8.85; df = 1; p = 0.002). The defects in POAG showed a characteristic radially-streaked pattern different from those described, for instance, in pigment dispersion syndrome, pseudoexfoliation syndrome, and acute glaucoma. Glaucoma patients with vascular dysregulation had a tendency to a higher incidence of transillumination defects than non-vasospastic patients, though this finding was not significant. CONCLUSIONS: Patients with POAG have a higher incidence of iris transillumination defects than controls. The underlying mechanisms are not yet clear and call for further investigation.