The relationship of macular microcirculation to visual acuity in diabetic patients
O. Arend, S. Wolf, A. Harris and M. Reim
Medical Faculty, Technical University of Aachen, Germany.
OBJECTIVE: To assess the perifoveal microcirculation in diabetic
maculopathy without clinically significant macular edema and its
relationship to visual acuity. DESIGN: Prospective analysis. SETTING: A
teaching hospital. PATIENTS: Fifteen patients with impaired visual acuity
of 20/50 or worse, a diabetic control population with unaffected visual
acuity (matched age, gender, retinopathy stage), and 52 healthy controls
were enrolled. INTERVENTIONS: Study consisted of video-fluorescein
angiography with image analyses and hemoglobin A1c measurements. MAIN
OUTCOME MEASURES: Macular capillary blood velocity, capillary density
(perifoveal intercapillary area), and foveal avascular zone. RESULTS: The
capillary blood velocity was significantly reduced in both diabetic groups
(P < .001) when compared with healthy controls, but did not differ
significantly among the two diabetic groups. The perifoveal intercapillary
area and foveal avascular zone were significantly enlarged in both diabetic
groups compared with healthy controls (P < .001). The foveal avascular
zone (P < .01) and perifoveal intercapillary area (P = .01) were further
enlarged in the diabetics with reduced visual acuity. The visual acuity
correlated significantly with foveal avascular zone (R2 = .51) and
perifoveal intercapillary area (R2 = .24), indicating an association
between enlargement and declined visual acuity. CONCLUSIONS: Capillary
blood velocity remained unchanged regardless of presence of visual
impairment, whereas foveal avascular zone and perifoveal intercapillary
area indicated ischemia. This may help in defining a critical hypoxic
threshold for visual loss and identifying the presence of an ischemic
diabetic maculopathy.
