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Nick Muthiah, Kunal K Dansingani, Travis Smith, Michel Michaelides, Pete Coffey, Lyndon Da Cruz; Longitudinal study of in-vivo Cone Photoreceptor Structural – Functional Changes in Ischemic Diabetic Maculopathy. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4599.
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© ARVO (1962-2015); The Authors (2016-present)
To assess, longitudinally, the structure-function correlates in patients with ischemic diabetic maculopathy, using adaptive optics (AO) retinal imaging with the rtx1 system (Imagine Eyes, Orsay, France) and microperimetry (MP).
AO imaging was performed of the retina in 5 eyes (3 patients) who had previously been diagnosed with extrafoveal macular ischemia on flourescein angiography (FA). AO images were taken at baseline, 6 months and 1 year following FA. The imaging findings (cone density and hexagonality) were then correlated with microperimetry (MP), ETDRS grading of the ischemia on FA was undertaken, and AO data were compared to spectral-domain optical coherence tomography (SD-OCT).
Baseline cone densities in the disease set ranged from 0.23×103 to 5.0×103 cones/mm2 and, at follow up, ranged from 1.04×103 to 25.3×103 cones/mm2. Longitudinal follow up demonstrated that the cone density can both worsen (2 eyes) and improve (3 eyes). The 5 ischemic foci at the follow up visit had cone hexagonality (6-sides, 6ns) in the range of 23.1% to 33.2%, compared to baseline, where hexagonality was 7.7% to 33.3%.Cone density index (as % of age-matched normal cone density) showed good correlation to MP retinal sensitivity (r = 0.66, p = 0.038) p < 0.05. The greater the DMI severity, as per ETDRS grading, the lower was the cone density index (rs = -0.79, p = 0.001) p < 0.01. There was no significant correlation between photoreceptor outer segment (OS) length on OCT and cone density index.Restoration of cone OS reflectance was seen most notably in 2 patients; in the first a 20-fold cone density increase occurred within the ischemic focus with a rise in MP retinal sensitivity from 9 dB to 18 dB. Improvement was also seen in the fellow eye, with a 4.5-fold cone density increase and a MP retinal sensitivity improvement from 6 dB to 8 dB. A second patient experienced the most significant improvement with doubling of cone density from < 0.5×103 to > 1.0×103 in the ischemic focus, and retinal sensitivity increase from 0 dB to 4 dB.
Cone photoreceptor OS regeneration, seen in vivo on AO, is a new finding in ischemic diabetic maculopathy. Future studies with larger cohorts might relate cone recovery to glycated HbA1c.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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