Local retinal dysfunction strikes in type 1 diabetes patients showing no signs of DR
Electroretinogram-assessed localized retinal dysfunction in type 1 diabetes mellitus (DM1) patients appears to occur even in the absence of clinical signs of diabetic retinopathy (DR), and this incidence is associated with ageing, according to a study.
Multifocal electroretinograms (mfERG) were recorded in 35 eyes of 18 patients with no DR, in 38 eyes of 19 patients with mild signs of nonproliferative DR (NPDR) and in 31 eyes of 17 healthy controls.
Researchers measured response amplitude densities (RADs) of the N1-P1 components, as well as P1 implicit times (ITs), from isolated (R1: 0°–2.5°, R2: 2.5°–5°, R3: 5°–10°) and combined (R1 + R2, R2 + R3 and R1 + R2 + R3) annular rings and from four retinal sectors (nasal, temporal, superior and inferior) with increasing eccentricities up to 10° (S1, S2, S3, S1 + S2, S1 + S2 + S3).
There were significant differences in mfERG RADs, but not ITs, from all isolated and combined rings and sectors up to 10° of foveal eccentricity between the DM1 groups and controls. Results were comparable between NO DR and NPDR DM1 patients.
On Pearson’s test, the mfERG abnormalities of the central retinal areas showed a significant correlation with age in both DM1 groups, as well as with diabetes duration but only in the NPDR group.
The findings point to the potential of using mfERG in detecting localized retinal areas with functional impairment, researchers said. Clinicians should be aware that neuroretinal dysfunction is present much in advance with respect to the clinical onset of DR.
The study data may prove useful in assessing functional (in association to structural) indicators of DR progression and identifying different phenotypes of DR with different risks of developing vision-threatening complications with the aim of understanding diabetic pathologic mechanisms and pursuing personalized management, researchers added.