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Leo Sheck, Dianne M. Sharp, Andrea L. Vincent; Differentiating ABCA4 And MIDD Maculopathies Using Fundal Autofluorescence And High Definition Optical Coherence Tomogrpahy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2392.
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Considerable overlap in macular phenotypes exists between ABCA4 and MIDD maculopathy. This study aims to compare the macula phenotypes associated with ABCA4 maculopathy with that in maternally inherited diabetes and deafness (MIDD) (mt3243A>G positive) using High-Definition Spectral-Domain Optical Coherence Tomography (SD-OCT) and confocal scanning laser ophthalmoscope fundus autofluorescence (FAF).
Patients recruited from a tertiary Ocular Genetics Clinic with a maculopathy associated with a confirmed genotype of ABCA4 or the mitochondrial mt.3243A>G. A complete ophthalmological examination, including ERG, was done. SD-OCT and FAF were performed with the Spectralis HRA SD-OCT
Twelve eyes from 6 ABCA4-positive patients and 4 eyes from 2 patients with mt.3243A>G mutations were examined. FAF images were obtainable in 10 eyes with ABCA4 maculopathy and all 4 eyes with mt.3243A>G maculopathy. FAF was variable in ABCA4 maculopathy. 6 eyes demonstrated well defined areas of absent autofluorescence involving the fovea and 4 of these eyes have surrounding speckled hyperfluorescence, 4 eyes showed hyperfluorescent flecks, and 6 eyes had mottled hypofluorescent areas. All eyes with MIDD maculopathy showed well defined areas of absent autofluorescence in the posterior pole with surrounding speckled hyperfluorescence. In contrast to ABCA4 maculopathy, the absent autofluorescent areas in MIDD spared the fovea. The MIDD maculopathy visualised with SD-OCT revealed a sharp edge with abrupt loss of outer nuclear layer (ONL), external limiting membrane (ELM), photoreceptor inner segment / outer segment (IS/OS) layer , and attenuation of the retinal pigment epithelium (RPE) layer. This corresponded to the boundary of absent autofluorescence. In contrast, in the eyes with ABCA4 maculopathy and absent autofluorescence, SD-OCT showed a gradual loss of retinal thickness at the boundary of the absent autofluorescence, with loss of IS / OS layer extending beyond the area of absent autofluorescence in all 6 eyes. It appeared that RPE attenuation is better correlated with areas of absent autofluorescence.
Ocular imaging utilising FAF and SD-OCT is able to detect significant differences between the ABCA4 and MIDD maculopathies, particularly in the periatrophic regions. In conjunction with clinical history, pedigree and clinical exam, these tools allow clinicians to tailor targeted genetic testing when faced with a patient with possible genetic maculopathy.
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