Quantification of macular ischaemia in sickle cell retinopathy

Macular ischaemia has a central role in the pathophysiology and prognosis of retinal macular disease. We attempted to quantitate two of its major components as follows: vascular nonperfusion, by measuring the foveal avascular zone (FAZ), using fluorescein angiography; and functional damage, using automated perimetry of the central 30 degrees. Sickle cell disease was chosen for study because it was considered a prototype for a purely ischaemic retinopathy without an exudative component. We found that the FAZ measurement was reproducible and that the patients with maculopathy had statistically larger FAZs than the normal controls (p = 0.016, Wilcoxon rank sum test). In addition, scotomas measured by visual field perimetry were significantly larger in the sickle cell patients with maculopathy than in those without maculopathy. Our results showed that angiography and perimetry of the central 30 degrees were more sensitive tests for the detection of ischaemic macular disease than visual acuity and that macular ischaemia could be quantified by their use.