Purpose: To study retinal function in asymptomatic Type 1 and Type 2 diabetic patients with nonproliferative diabetic retinopathy (NPDR) and no clinical signs of diabetic macular edema.
Methods: Thirty-six consecutive Type 1 and Type 2 diabetic patients with nonproliferative diabetic retinopathy and no diabetic macular edema and 28 healthy controls underwent a complete ophthalmologic examination, including spectral domain optical coherence tomography and microperimetry.
Results: Seventy-one eyes (17 patients with Type 1 and 19 with Type 2 diabetes) were tested, and data from 36 (17 Type 1 and 19 Type 2) eyes were analyzed. Mean best-corrected visual acuity was 0.00 ± 0.01 logMAR and 0.00 ± 0.02 logMAR for Type 1 and Type 2 diabetic patients, respectively (P = 0.075). Mean central foveal thickness was 234.5 ± 13.7 μm and 256.3 ± 12.7 μm for Type 1 and Type 2 diabetic patients, respectively (P = 0.04); the central foveal thickness was statistically different compared with the control groups (P = 0.04 and P = 0.01, respectively). Mean retinal sensitivity was 18.9 ± 0.5 dB and 17.7 ± 0.4 dB for Type 1 and Type 2 diabetic patients, respectively; it was statistically different compared with control groups (P < 0.0001 and P < 0.0001, respectively).
Conclusion: We demonstrated a significantly reduced sensitivity in both nonproliferative diabetic retinopathy groups without diabetic macular edema compared with healthy controls; this reduction was greater in Type 2 diabetic patients. Central foveal thickness was increased in all diabetic patients compared with healthy controls, despite the absence of diabetic macular edema.
In eyes with nonproliferative diabetic retinopathy and no clinical signs of diabetic macular edema, microperimetry shows a reduction in retinal sensitivity, to a greater extent in patients affected by Type 2 diabetes than Type 1 diabetes.
*Department of Ophthalmology, Scientific Institute San Raffaele, University Vita Salute San Raffaele, Milan, Italy;
†Department of Ophthalmology, University of Paris Est Creteil, Centre Hospitalier Intercommunal de Creteil, Creteil, France; and
‡Epidemiology Unit, Scientific Institute San Raffaele, Milan, Italy.
Reprint requests: Giuseppe Querques, MD, PhD, Department of Ophthalmology, University Vita Salute San Raffaele, Via Olgettina 60, 20132 Milan, Italy; e-mail: firstname.lastname@example.org
Contributions to authors in each of these areas: Study design and conduct (U.D., G.Q., F.B.); data collection, management, analysis (U.D., G.Q., R.L., E.B., G.T., G.M., G.C.), and interpretation (U.D., G.Q., F.B.); manuscript preparation (U.D., G.Q., E.B., G.T., F.B.), review, or approval (G.Q., F.B.).
None of the authors have any financial/conflicting interests to disclose.