Retinal Function and Fundus Autofluorescence Imaging in Patients with Maternal Inherited Diabetes and Deafness (MIDD)

Abstract

Abstract: : Purpose: To investigate retinal function in patients with maternally inherited diabetes and deafness (MIDD) and to correlate the findings with fundus autofluorescence (FAF) imaging. Methods: FAF was imaged in 4 patients (age range: 49-60 years) confirmed to have the mitochondrial DNA nucleotide A3243G point mutation. Retinal function was measured by Ganzfeld electroretinography (ERG) and pattern ERG, performed to incorporate the ISCEV-standard. Multifocal ERG (mfERG; RETIscan System, Roland Consult, Germany) was also performed, binocularly in 3 patients and monocularly in 1 patient due to strabismus. The stimulus used in the mfERG consisted of 61 hexagons, covering in total 56.9 degree of visual field. For analysis of the mfERG data 5 regional ring groups of equal eccentricity were formed. For each ring the peak amplitude (defined as the difference between P1 and N1) and the implicit time of P1 were determined and compared to normative values. Results: Visual acuity in the patients was between 20/40 and 20/20 (ETDRS-chart). Irregular increased FAF signals were observed adjacent to and between areas of atrophy of the retinal pigment epithelium (RPE) (Rath PP, ARVO Abstract # 4345, 2002). Ganzfeld ERGs were within normal limits for 3 patients. One patient showed bilaterally reduced rod-specific b-wave amplitudes. Pattern ERG was abnormal in both eyes of 2 patients. In all patients the mfERG peak amplitudes were significantly reduced in rings 2-5 (p<0.05). No implicit times changes were present. Conclusions: While the Ganzfeld photopic ERG was normal in all patients the mfERG cone responses showed significant reductions. This is topographically consistent with heterogeneous damage to the central retina in MIDD. On mfERG recordings dysfunction was most obvious in rings 2 and 3. This was consistent with areas of increased FAF as well as with decreased FAF (RPE atrophy). Reduced peak amplitudes with normal implicit times in the mfERG may indicate localized damage to the cone photoreceptor outer segments or cone photoreceptor loss in MIDD.

Keywords: electroretinography: clinical • imaging/image analysis: clinical • retinal degenerations: hereditary