Measuring retinal sensitivity with the microperimeter in patients with diabetes

To evaluate the retinal sensitivity and fixation characteristics in participants with diabetes mellitus, using the microperimeter (MP-1) and to correlate the MP-1 values with the severity of diabetic retinopathy (DR).

We performed complete ophthalmic examinations, including best-corrected visual acuity, slit-lamp examination, indirect ophthalmoscopy, and microperimetry (central 20° of macula) on 210 eyes of 160 participants. Participants included healthy individuals, individuals with diabetes but no retinopathy, and individuals with different stages of DR.

The mean age of participants was (mean ± SD) 49.83 ± 7.43 years for healthy individuals, 53.20 ± 5.7 years for participants with diabetes but no retinopathy, and 55.39 ± 7.81 years for participants with DR. Retinal sensitivity was significantly (P = 0.001) decreased with severity of DR. The mean foveal sensitivity (retinal sensitivity in the central 2°) was 16.68 ± 2.13 dB in healthy individuals, 14.73 ± 3.64 dB in participants with diabetes but no DR, and 11.60 ± 5.76 dB in participants with DR. There was significant loss of retinal sensitivity in participants with diabetes but no retinopathy when compared with healthy individuals. Participants with severe nonproliferative DR showed more significant loss of retinal sensitivity in the central 20° than those with other stages of DR.

The MP-1 is a useful tool to quantify retinal sensitivity in DR. Using the MP-1, we can detect early loss of retinal sensitivity in patients with diabetes but no retinopathy. Patients with severe nonproliferative DR will have less retinal sensitivity than those with other stages of DR. Scotoma mapping using the MP-1 provides details of functional vision in patients with DR.