Functional Retinal Impairment in Type 1 Diabetic Patients without any Signs of Retinopathy

Purpose: To investigate functional and morphological retinal changes in the long-term follow-up in subjects with type 1 diabetes mellitus (DM1) without any signs of retinal vasculopathy. Methods: Functional testing included Humphrey Matrix perimetry (30-2 threshold program) and white-on-white Humphrey perimetry (HFA, 30-2 SITA standard), while retinal nerve fibre layer (RNFL) thickness was measured by scanning laser polarimetry with variable corneal birefringence compensator. Results: Data from 20 eyes of 20 subjects with DM1 were analysed. No changes of HFA mean deviation (MD: -2.20 ± 3.44 vs. -1.63 ± 2.47; p = 0.14) and pattern standard deviation (PSD: 2.50 ± 1.71 vs. 2.28 ± 1.36; p = 0.31), and Matrix MD (-1.06 ± 3.62 vs. -1.24 ± 2.99; p = 0.65) were found after 5 years. A significant change was found for Matrix PSD between baseline and the end of follow-up (2.76 ± 0.59 vs. 3.1 ± 0.68; p = 0.0078). RNFL parameters were not changed. A significant relationship was found between HbA1c levels and changes from baseline of Matrix PSD (R2 0.29, p = 0.02). Conclusions: Progressive retinal functional impairment could be detected in DM1 subjects by frequency doubling perimetry before the onset of any overt retinal vasculopathy and functional impairment seems to be significantly related to glycaemic control.