AQUEOUS-HUMOR DYNAMICS IN PATIENTS WITH DIABETES-MELLITUS

PURPOSE: We measured aqueous dynamic variables in subjects with diabet es mellitus and correlated them with severity of retinopathy and metab olic control to determine whether diabetes affects the anterior circul ation of the eye as it affects the posterior (retinal) circulation. ME THODS: Sixty-one subjects with diabetes mellitus type 1 and 60 subject s with diabetes mellitus type 2 were recruited from the active practic e of the Mayo Clinic. Thirty-two normal subjects, divided by age into two overlapping groups of 20 each, served as contemporaneous control s ubjects. The diabetic subjects were stratified into four groups accord ing to severity of retinopathy. Aqueous humor now was measured by clea rance of topically applied fluorescein with a spectrofluorophotometer; outflow facility was measured by tonography; and intraocular pressure was measured by applanation tonometry. RESULTS: In type 1 diabetics, the mean intraocular pressure was slightly greater (14 +/- 3 mm Hg), c ompared with control subjects (12 +/- 2 mm Hg [P =.002]), while aqueou s humor flow was slightly less (2.5 +/- 0.6 mu l/min), compared with c ontrol subjects (2.9 +/- 0.5 mu l/min [P = .023]). In type 2 diabetics , the intraocular pressure was 14 +/- 3 mm Hg, which did not differ fr om that of control subjects (14 a 3 mm Hg [P =.258]). Aqueous humor fl ow in type 2 diabetics (2.5 +/- 0.7 mu l/min) did not differ significa ntly from that of the control group (2.5 +/- 0.7 mu l/min [P =.961]). Tonographic facility of outflow was not significantly differ ent in ty pe 1 and type 2 diabetics and the control subjects. There was no signi ficant correlation in aqueous humor now, intraocular pressure, or tono graphic facility of outflow to severity of retinopathy or hemoglobin A (1c) in either type 1 or type 2 diabetics. CONCLUSION: The dynamics of aqueous humor are not affected to any clinically significant extent i n the early or middle stages of diabetic retinopathy. However, there i s a tendency toward less aqueous humor flow in the advanced stages of retinopathy.