Purpose: The purpose of this study was to assess density and morphology of cone photoreceptors (PRs) and corresponding retinal sensitivity in ischemic compared to nonischemic retinal capillary areas of diabetic eyes using adaptive optics optical coherence tomography (AO-OCT) and microperimetry (MP).
Methods: In this cross-sectional, observational study five eyes of four patients (2 eyes with proliferative diabetic retinopathy (DR) and 3 eyes moderate nonproliferative DR) were included. PR morphology and density was manually assessed in AO-OCT en face images both at the axial position of the inner-segment outer segment (IS/OS) and cone outer segment tips (COSTs). Retinal sensitivity was determined by fundus-controlled microperimetry in corresponding areas (MP-3, Nidek).
Results: In AO-OCT, areas affected by capillary nonperfusion showed severe alterations of cone PR morphology at IS/OS and COST compared to areas with intact capillary perfusion (84% and 87% vs. 9% and 8% of area affected for IS/OS and COST, respectively). Mean reduction of PR signal density in affected areas compared to those with intact superficial capillary plexus (SCP) and deep capillary plexus (DCP) perfusion of similar eccentricity was -38% at the level of IS/OS (P = 0.01) and -39% at the level of COST (P = 0.01). Mean retinal sensitivity was 10.8 ± 5.4 in areas affected by DCP nonperfusion and 28.2 ± 1.5 outside these areas (P < 0.001).
Conclusions: Cone PR morphology and signal density are severely altered in areas of capillary nonperfusion. These structural changes are accompanied by a severe reduction of retinal sensitivity, indicating the importance of preventing impaired capillary circulation in patients with DR.
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http://dx.doi.org/10.1167/iovs.62.13.1 | DOI Listing |
J Vis Exp
December 2024
Department of Ophthalmology and Visual Neurosciences, University of Minnesota;
G protein-coupled receptors (GPCRs) are a superfamily of transmembrane proteins that initiate signaling cascades through activation of its G protein upon association with its ligand. In all mammalian vision, rhodopsin is the GPCR responsible for the initiation of the phototransduction cascade. Within photoreceptors, rhodopsin is bound to its chromophore 11-cis-retinal and is activated through the light-sensitive isomerization of 11-cis-retinal to all-trans-retinal, which activates the transducin G protein, resulting in the phototransduction cascade.
View Article and Find Full Text PDFUnlabelled: Sensory stimuli vary across a variety of dimensions, like contrast, orientation, or texture. The brain must rely on population representations to disentangle changes in one dimension from changes in another. To understand how the visual system might extract separable stimulus representations, we recorded multiunit neuronal responses to texture images varying along two dimensions: contrast, a property represented as early as the retina, and naturalistic statistical structure, a property that modulates neuronal responses in V2 and V4, but not in V1.
View Article and Find Full Text PDFMethodsX
June 2025
Assistant Professor, Department of Electronics and Communication Engineering, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Tamil Nadu, 600062, India.
Glaucoma, a severe eye disease leading to irreversible vision loss if untreated, remains a significant challenge in healthcare due to the complexity of its detection. Traditional methods rely on clinical examinations of fundus images, assessing features like optic cup and disc sizes, rim thickness, and other ocular deformities. Recent advancements in artificial intelligence have introduced new opportunities for enhancing glaucoma detection.
View Article and Find Full Text PDFOphthalmol Glaucoma
January 2025
Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA. Electronic address:
Purpose: To investigate the impact of blood pressure (BP) on rates of retinal nerve fiber layer (RNFL) thinning in glaucomatous eyes with focal ischemic (FI) versus generalized enlargement (GE) optic disc phenotypes.
Design: Prospective cohort study.
Participants: The study included 122 eyes from 101 patients diagnosed with primary open-angle glaucoma.
J Optom
January 2025
Department of Ophthalmology, Peking University People's Hospital, Beijing, China; Eye Diseases and Optometry Institute, Beijing, China; Beijing Key Laboratory of Diagnosis and Therapy of Retinal and Choroid Diseases, Beijing, China; College of Optometry, Peking University Health Science Center, Beijing, China.
Purposes: To investigate the 12-month effectiveness of Diverse Segmented Defocus Optics (DSDO) and Defocus Incorporated Multiple Segments (DIMS) spectacle lenses in a real-world clinical population in myopic and pre-myopic Chinese children.
Methods: About 364 subjects prescribed DSDO or DIMS were enrolled. Axial length (AL) and cycloplegic spherical equivalent refraction (SER) changes over 12 months were measured.
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