Angelos Kalitzeos

Aim To study structure-function correlates using adaptive optics retinal imaging (AORI) and microperimetry in patients with diabetic macular ischaemia (DMI). Methods En-face AORI in 7 DMI eyes in regions of interest (ROI) with fluorescein angiography evidence of enlarged foveal avascular zone and in seven control eyes. Microperimetry and optical coherence tomography (OCT) scans were also performed. Cone density index (CDI)=percentage ratio of cone density, hexagonality ratio (Hr)=ratio of hexagonal cones (6 ns) to all sided cones (4–8 ns) and inter-cell distance (ICD) in DMI/control eyes were measured. Retinal sensitivity and inner-segment ellipsoid (ISel) band were assessed. ETDRS DMI grading performed. Results Photoreceptor metrics in two eyes (3 ROIs) with ETDRS grade 2 (mild) ischaemia: mean Hr 0.90 (SD=0.12) and mean CDI 40.2 (SD=16.9), in the two eyes (3 ROIs) with ETDRS grade 3 moderate ischaemia: lower mean Hr 0.69 (SD=0.08) and mean CDI 12.0 (SD=9.5), and in three eyes (3 ROIs) with severe ETDRS grade 4 ischaemia: significantly lower mean Hr 0.37 (SD=0.19) and mean CDI 1.9 (SD=1.7). Significant correlation of CDI, Hr and ICD to ETDRS DMI severity; r_s=−0.90, p=0.001 (ps=−0.84, p=0.004 (ps+0.74, p=0.023 (pConclusions AORI detected photoreceptor changes with high correlation to ischaemia and function, often unaccompanied by ISel abnormalities on OCT.

Purpose: To determine the repeatability of retinal blood vessel parameters (from proprietary software and the raw vessel data) measured in vivo in healthy individuals at rest, during and post flicker light (FL) provocation using a standardised protocol. Methods: We recorded the diameters of one retinal artery and one vein in each of 33 healthy adult volunteers at rest, during and post FL provocation on two occasions using the Retinal Vessel Analyser (RVA). Repeat visits were scheduled at three different timepoints: (1) within 30 mins on the same day, (2) within a fortnight and (3) within a month ( n = 11, each). All participants underwent intraocular and systemic blood pressure assessment to ensure these were comparable between visits. Results: Retinal vessel parameters at rest, during and post FL provocation were comparable between all pairs of visits for all three groups. Repeatability between visits was assessed using Bland–Altman Analyses and Intraclass Correlation Coefficients (ICCs). Maximum dilation for arteries and veins and maximum constriction for arteries due to FL provocation computed from raw dilation data showed better repeatability than that generated by the RVA software. Time to reach maximum dilation in arteries and veins and maximum constriction in arteries was on average comparable but least repeatable between visits. Conclusions: Retinal vessel parameters computed from the raw RVA data may be superior in quality to the output from the proprietary software because the latter uses fixed narrow time‐windows to determine the parameters. Variance within healthy controls, pathology groups and repeatability parameters alongside systemic haemodynamic parameters should be considered when utilising dynamic retinal vascular parameters as study endpoints.

Background/aims: The purpose of this study was to investigate retinal structure in detail of subjects with autosomal-dominant (AD) and autosomal-recessive (AR)PROM1-associated retinal degeneration (PROM1-RD), study design: institutional, cross-sectional study.Methods: Four eyes from four subjects (three with AD and one with AR)PROM1-RD were investigated by ophthalmic examination including best-corrected visual acuity (BCVA) and multimodal retinal imaging: fundus autofluorescence (FAF), spectral-domain optical coherence tomography (SD-OCT) and adaptive optics scanning light ophthalmoscopy. Quantitative assessment of atrophic lesions determined by FAF, thickness of individual retinal layers and cone photoreceptor quantification was performed.Results: BCVA ranged from 20/16 to 20/200. Initial pathological changes included the presence of hyperautofluorescent spots on FAF imaging, while later stages demonstrated discrete areas of atrophy. In all patients, thinning of the outer retinal layers on SD-OCT with varying degrees of atrophy could be detected depending on disease-causing variants and age. Cone density was quantified both in central and/or at different eccentricities from the fovea. Longitudinal assessments were possible in two patients.Conclusions: PROM1-RD comprises a wide range of clinical phenotypes. Depending on the stage of disease, the cone mosaic inPROM1-RD is relatively preserved and can potentially be targeted by cone-directed interventions.