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%; chi(2) = 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.