Mathieu Flores

Reliability of cone counts using an adaptive optics retinal camera

To assess the reproducibility and repeatability of cone imaging in healthy human eyes, using the RTx‐1 Adaptive Optics Retinal Camera and its proprietary cone‐counting software.

Quantification of cone loss after surgery for retinal detachment involving the macula using adaptive optics

Aims To image the cones in eyes with anatomically successful repair of retinal detachment (RD) involving the macula and in healthy fellow eyes using an adaptive optics (AO) camera and to correlate the results to clinical outcomes. Methods Twenty-one patients (42 eyes) operated for macula-off RD were imaged 6 weeks after surgery using an AO camera (RTX 1, Imagine Eyes, Orsay, France). Cone density (cells/mm2), spacing between cells (µm) and the percentage of cones with six neighbours were measured. Best-corrected visual acuity (BCVA) and thickness of the inner segment ellipsoid (ISe) band imaged by SD-optical coherence tomography were also measured. Results The parafoveal cone density was decreased in eyes operated for RD (mean±SD 14 576±4035/mm2) compared with fellow eyes (20 589±2350/mm2) (p=0.0001). There was also an increase in cone spacing (10.3±2.6 vs 8.0±1.0.9 µm, respectively, p<0.0001). The nearest-neighbour analysis revealed a reduction in the percentage of cones with six neighbours (36.5±4.2 vs 42.7±4.6%, p=0.0003). The ISe thickness, thinner in the operated eyes, was correlated to the cone density (r=0.62, p<0.0001). BCVA was significantly correlated to cone density (r=0.8, p<0.001). Conclusions There was a decrease in the cone density after RD with an estimated loss of one-third of the cones. Postoperative visual acuity was highly correlated with the cone density. AO may be a valuable prognostic tool after RD surgery.

Reflectivity of the Outer Retina on Spectral-Domain Optical Coherence Tomography as a Predictor of Photoreceptor Cone Density

PURPOSE To investigate the relationship between outer retinal reflectivity on spectral-domain optical coherence tomography and cone density in the corresponding area. DESIGN Prospective cross-sectional observational study. METHODS In this institutional-based study, 20 eyes of 10 patients presenting maculopathies with various degrees of impairment of the photoreceptor layer (central serous chorioretinopathy, chronic central serous chorioretinopathy, maculopathy associated with hydroxychloroquine, and healthy eyes) were studied. Selection criteria were intended to ensure good image quality. Inner segment ellipsoid band reflectivity, global retinal reflectivity, and relative inner segment ellipsoid reflectivity (defined as the ratio of inner segment ellipsoid band reflectivity on overall retinal reflectivity) were measured on a longitudinal reflectance profile extracted from the spectral-domain optical coherence tomography B-scan. The cone metrics were measured in the same region of interest, located in the perifoveal area, using an adaptive optics retinal camera. RESULTS Inner segment ellipsoid and relative ellipsoid reflectivity were closely correlated with cone density (Pearson r: 0.72 and 0.70, respectively, P < .01). CONCLUSION Outer retinal reflectivity on the transversal optical coherence tomography scan can be correlated to adaptive optics in terms of photoreceptor density. This quantitative approach using optical coherence tomography images could have important implications in the management of maculopathies.

Assessment of parafoveal cone density in patients taking hydroxychloroquine in the absence of clinically documented retinal toxicity.

To measure cone density in patients taking hydroxychloroquine (HCQ), with no clinical evidence of maculopathy.

Three-dimensional Printing of Optical Lenses and Ophthalmic Surgery: Challenges and Perspectives

PURPOSE To determine whether the historical Ridley lens could be reproduced with current three-dimensional lens printing technology. METHODS A reproduction of the Ridley lens was printed using the Printoptical Technology (LUXeXceL Group BV, Kruiningen, Netherlands). Photographs and electron microscopy images were taken. Dimensions, weight, anterior and posterior surface radius of curvature, optical transmission, back optical power, and surface analysis using interferometry were obtained. RESULTS The printed lens was 8.10 ± 0.01 mm in diameter, 2.50 ± 0.01 mm thick, and weighed 117 mg. The anterior radius of curvature was 14.63 ± 0.69 mm and the posterior radius of curvature was 10.88 ± 0.22 mm. The back focal length in air was 14.1 ± 0.4 mm. An average 75% transmission in the visible spectrum (400 to 700 nm) was achieved. Surface analysis showed significant surface roughness. CONCLUSIONS The printed reproduction of the Ridley lens was far from current clinical standards, but had the properties of a biconvex lens.

Retinal Reflectivity Measurement for Cone Impairment Estimation and Visual Assessment After Diabetic Macular Edema Resolution (RECOVER-DME)

Purpose Photoreceptor loss has been suspected of being involved in incomplete visual recovery after diabetic macular edema (DME) resolution. Recent studies have shown that cone density in the perifoveal area could be estimated by in vivo measurements of the outer retinal reflectivity on optical coherence tomography (OCT). The main objective of this study was to assess the photoreceptor layer reflectivity after DME resolution and to determine its relationship with final visual acuity (VA). Methods In this cross-sectional case-control study, 77 eyes of 58 patients were divided into three groups: a first group (n = 34) encompassed eyes with resolved DME (R-DME), a second group (n = 24) corresponded to diabetic eyes without DME (no-DME), and a third group (n = 19) comprised a control group of nondiabetic healthy eyes. Outer retinal reflectivity was measured on volumetric spectral-domain (SD)-OCT scans acquired 3 months after DME resolution, from the photoreceptor ellipsoid zone (EZ) and the retinal pigment epithelium (RPE). Results The mean DME duration was 26.5 ± 13.4 months in the R-DME group. EZ reflectivity was 19.8% lower (P < 0.0001) in this group compared to diabetic eyes without DME and 26.5% lower (P < 0.0001) than in nondiabetic control eyes. Reflectivity was 7.8% lower in the no-DME group compared to controls (P < 0.0001). RPE reflectivity was comparable among the three groups (P > 0.05). VA was significantly correlated with EZ reflectivity in diabetic patients (r2 = 0.57; P < 0.0001). Reflectivity tended to decrease with prolonged DME duration without reaching statistical significance (P = 0.10). Conclusions DME significantly impacts the photoreceptor layer. This impairment can be estimated by measuring outer retinal reflectivity on OCT images after edema resorption. We also provide evidence that in diabetic eyes without a history of DME, there is early photoreceptor loss, or at least outer segment (OS) disorganization, in addition to the inner retinal degeneration reported previously. This suggests the neurodegenerative process in diabetes. This quantitative approach may help monitor neuroprotective strategies to rescue photoreceptor cells in diabetic eyes.

Optical and morphological characterization of a 3D printed intraocular lens

Purpose Three‐dimensional printing (or “additive manufacturing”) is a technology which allows to create a three dimensional object by building it layer by successive layer. It is especially interesting for objects that are produced in little series and that require a high degree of customization, as it allows economies of scale and potentially unlimited design possibilities. Those characteristics are particularly relevant to intraocular lenses used in cataract surgery, in a personalized medicine approach. Despite technical barriers, additive manufacturing of good quality lenses without post‐processing is now achievable. We aimed to determine if the historical Ridley lens was able to be reproduced with current 3D lens printing technology.