Fig 1.
Adaptive optics montage of the central retina in the right eye of a patient with a diagnosis of type 1 diabetes mellitus in the past 37 years (DM1_P7).
A) Wide field fundus image. The arrow highlights a cluster of spot hemorragies outside the region of interest. B) Adaptive optics montage of the central retina showing the photoreceptor mosaic (2.46x2.18 mm). Analysis of the cone mosaic was done in 160x160 μm sampling areas on four locations at 1.5 degrees eccentric from the fovea along all retinal meridians. Scale bar: 160 μm.
Table 1.
Characteristics of the study population.
Patients with type 1 diabetes mellitus were identified as having mild nonproliferative diabetic retinopathy (NPDR) or not (noDR) by fundoscopy.
Table 2.
Average (±SD) values of the cone metrics calculated by sampling data of the four paravofeal locations at 1.5 degrees eccentric from the fovea in patients with type 1 diabetes mellitus (DM1) with (NPDR) or without (noDR) signs of diabetic retinopathy on fundoscopy and age-matched controls.
Fig 2.
Adaptive optics images of the parafoveal cone mosaic and corresponding Voronoi diagrams in four patients with type 1 diabetes mellitus and two age-matched controls.
Upper row) Adaptive optics images of the parafoveal cone mosaic (160x160 μm) and bottom row) corresponding Voronoi diagrams in six age-matched representative cases (colour maps are described under Methods). From the left to the right are shown the images collected at 1.5 degrees inferior from the fovea in Control_36, Control_43, DM1_P9, DM1_P12, DM1_P2 and DM1_P4 respectively. The corresponding data from this parafoveal location were as follows: in Control_36 (39 years old), cone density was 29927 cones/mm2 and percentages of 6n and 4n+8n were 51% and 3% respectively; in Control_43 (33 years old), cone density was 28103 cones/mm2 and percentages of 6n and 4n+8n were 51% and 6% respectively; in DM1_P9 (35 years old, duration of DM1: 9 years), density was 29492 cones/mm2, and percentages of 6n and 4n+8n were 46% and 6% respectively; in DM1_P12 (36 years old, duration of DM1: 11 years), density was 27938 cones/mm2, and percentages of 6n and 4n+8n were 45% and 7% respectively; in DM1_P2 (35 years old, duration of DM1: 17 years), density was 23619 cones/mm2, and percentages of 6n and 4n+8n were 47% and 5% respectively; in DM1_P4 (35 years old, duration of DM1: 10 years), density was 23320 cones/mm2, and percentages of 6n and 4n+8n were 41% and 8% respectively. The packing arrangement of the parafoveal cones in eyes with diabetes showed on average less hexagonal cones and more non-hexagonal cones, which were associated with average decreased cone density, in comparison with controls.
Fig 3.
Box plots showing the distribution of values for cone density, linear dispersion index and heterogeneity packing index in patients with diabetes and controls.
Parallel box plots showing the distribution of values for parafoveal cone density (left plot; cones/mm2), linear dispersion index (middle plot; LDi, D.U.: dimensionless unit) and heterogeneity packing index (right plot; HPi, %) in patients with (NPDR) and without (noDR) signs of diabetic retinopathy on fundoscopy and controls. The blue plus sign and the line in each box represent the mean and median scores respectively; the lower and upper edges of each box represent the 25th and 75th percentiles, respectively. The upper and lower adjacents (i.e., the bars) include all the extreme values up to the 99th percentile. Red crosses represent outlier data points.
Fig 4.
Adaptive optics images of the photoreceptor mosaic for all patients with diabetes and eight representative age-matched controls acquired at 1.50 degrees superior from the fovea.
The upper row includes the eyes with noDR (from DM1_P9 to DM1_P16 from the left to right respectively), the middle row the eyes with NPDR (from DM1_P1 to DM1_P8 from the left to right respectively) and the lower row the control eyes (C30, C32, C33, C37, C39, C41, C44 and C48 from the left to right respectively). Each window is 160x160 μm. The cones were reliably identified in all AO images collected from study cases and controls.