Structural and Functional Correlation in Sickle Cell Retinopathy Using Spectral-Domain Optical Coherence Tomography and Scanning Laser Ophthalmoscope Microperimetry

Purpose: To correlate macular structural changes by spectral domain optical coherence tomography (SD-OCT) with functional changes by scanning laser ophthalmoscope (SLO) microperimetry testing in patients with sickle cell hemoglobinopathies. Design: Prospective, investigational study. Methods: Patients with electrophoretic confirmation of sickle cell hemoglobinopathies and normal subjects underwent SD-OCT and microperimetry testing with the OPKO Spectral OCT/SLO instrument. Based on SD-OCT findings, patients were grouped into those with focal macular thinning (Group A) and those without (Group B). Main outcome measure were mean retinal sensitivities measured by microperimetry and mean macular thicknesses in the 9 Early Treatment Diabetic Retinopathy Study (ETDRS)-like subfields. Results: Thirty-seven eyes of 19 patients with sickle cell hemoglobinopathies (SS, SC, and S-Thalassemia) and 34 eyes of 34 age similar normal controls were included. Mean age and mean logMAR best corrected visual acuity between Group A and B were not statistically different (39.7 years vs. 36.5 years, p = 0.64 and 0.015 vs. 0.016, p = 0.93, respectively). Group A had significantly thinner retinas compared to Group B in the parafoveal superior (p = 0.019), parafoveal temporal (p < 0.004), parafoveal inferior (p = 0.003), perifoveal superior (p = 0.04), perifoveal temporal (p = 0.0005), and perifoveal inferior (p = 0.045) subfields. The overall mean microperimetry retinal sensitivities of Group A were significantly less than those of Group B (14.2 dB vs. 16.5 dB, p = 0.00005). However, there was no statistical difference between Group B and controls (16.5 dB vs. 16.7 dB, p = 0.63). Conclusion: Sickle cell patients with focal macular thinning present on SD-OCT have significantly decreased retinal sensitivities compared to those without focal thinning or normal controls based on mean microperimetry sensitivities, despite similar age and visual acuity. Microperimetry is a sensitive measurement of macular function in patients with sickle cell hemoglobinopathies.