The Logistical Backbone of Photoreceptor Cell Function: Complementary Mechanisms of Dietary Vitamin A Receptors and Rhodopsin Transporters.

In this review, we outline our current understanding of the mechanisms involved in the absorption, storage, and transport of dietary vitamin A to the eye, and the trafficking of rhodopsin protein to the photoreceptor outer segments, which encompasses the logistical backbone required for photoreceptor cell function. Two key mechanisms of this process are emphasized in this manuscript: ocular and systemic vitamin A membrane transporters, and rhodopsin transporters. Understanding the complementary mechanisms responsible for the generation and proper transport of the retinylidene protein to the photoreceptor outer segment will eventually shed light on the importance of genes encoded by these proteins, and their relationship on normal visual function and in the pathophysiology of retinal degenerative diseases.

Adverse COVID-19 outcomes in American Veterans with age-related macular degeneration: a case-control study.

Objectives: Prior studies suggest that patients with age-related macular degeneration (AMD) have poorer COVID-19 outcomes. This study aims to evaluate whether AMD is associated with adverse COVID-19 outcomes in a large clinical database.

Design: Case-control study.

In Silico Prediction of MYO1C-Rhodopsin Interactions and Its Significance in Protein Localization and Visual Function.

Rods and cones are photoreceptor neurons in the retina that are required for visual sensation in vertebrates, where proper protein localization and compartmentalization are critical for phototransduction and visual function. In human retinal diseases, improper protein transport to the outer segment (OS) or mislocalization of proteins to the inner segment (IS) could lead to impaired visual responses and photoreceptor cell degeneration, causing a loss of visual function. We showed involvement of an unconventional motor protein, MYO1C, in the proper localization of rhodopsin to the OS, where loss of MYO1C in a mammalian model caused mislocalization of rhodopsin to IS and cell bodies, leading to progressively severe retinal phenotypes.

The role of motor proteins in photoreceptor protein transport and visual function.

Background: Rods and cones are photoreceptor neurons in the retina that are required for visual sensation in vertebrates, wherein the perception of vision is initiated when these neurons respond to photons in the light stimuli. The photoreceptor cell is structurally studied as outer segments (OS) and inner segments (IS) where proper protein sorting, localization, and compartmentalization are critical for phototransduction, visual function, and survival. In human retinal diseases, improper protein transport to the OS or mislocalization of proteins to the IS and other cellular compartments could lead to impaired visual responses and photoreceptor cell degeneration that ultimately cause loss of visual function.

Beneficial Effects of Spatial Remapping for Reading With Simulated Central Field Loss.

Purpose: People with central field loss (CFL) lose information in the scotomatous region. Remapping is a method to modify images to present the missing information outside the scotoma. This study tested the hypothesis that remapping improves reading performance for subjects with simulated CFL.

The Effect of Scleral Buckling Surgery on Choroidal Thickness Measured by Enhanced Depth Optical Coherence Tomography: A Cross-Sectional Study.

Introduction: To assess the anatomical changes taking place in the choroid after a scleral buckle (SB) procedure for retinal detachment repair.

Methods: This cross-sectional study looked at 23 adults with a history of unilateral retinal detachment repaired with a SB or other encircling element. The subjects underwent bilateral Enhanced Depth Spectral Domain Optical Coherence Tomography to image the choroid.

Strategies for Improving Patient Comfort During Intravitreal Injections: Results from a Survey-Based Study.

Introduction: Many ocular diseases require intravitreal injections of pharmacological agents. Optimizing patients' experiences during injections is important to ensure compliance and maintenance of quality of life. The objective of this study was to identify strategies to help alleviate discomfort during intravitreal injections.

Ultra Wide-Field Indocyanine Green Angiogram Highlights Choroidal Perfusion Delay Secondary to Giant Cell Arteritis.

Vision loss in giant cell arteritis (GCA) often presents as anterior ischemic optic neuropathy and central retinal artery occlusion. Previous studies have established an acute delay in choroidal perfusion on fluorescein angiography (FA) as a classic sign of GCA. The authors present a unique imaging case report of GCA where ultra wide-field (UWF) indocyanine green angiography (ICGA) offers improved characterization of delayed choroidal perfusion compared to FA.

Implantation of the Argus II Retinal Prosthesis in an Eye With Short Axial Length.

The authors describe the implantation of the Argus II Retinal Prosthesis System (Argus II) (Second Sight Medical Products, Sylmar, CA) into a short axial length (AL) eye. The authors' main modification is the use of endocyclophotocoagulation (endo-CPC) to the ciliary processes in the area that the cable enters through the sclerotomy. This case describes the surgical technique necessary for successful implantation of the Argus II into a short AL eye.

Association of Disorganization of Retinal Inner Layers With Vision After Resolution of Center-Involved Diabetic Macular Edema.

Importance: Macular edema (ME) prognosis and treatment response vary according to the underlying abnormalities. Biomarkers of visual acuity (VA) improvement could influence management decisions in different types of ME.

Objective: To investigate whether disorganization of retinal inner layers (DRIL) and other spectral-domain optical coherence tomography (SD-OCT)-derived variables are associated with subsequent VA after ME resolution in both nondiabetic and diabetic ME.

The heritability of the ring-like distribution of macular pigment assessed in a twin study.

Purpose: It has been suggested that ring-like patterns of macular pigment, as measured with dual wavelength autofluorescence, are observed less frequently in subjects with age-related maculopathy. We explored relative contributions of genetic and environmental factors in macular pigment optical density (MPOD) distributions using a classic twin study.

Methods: As part of a previous nutritional study, 322 healthy Caucasian female twins, aged 16 to 50 (mean 40) years, underwent measurement of MPOD optical density by two-wavelength fundus autofluorescence.

High-resolution multimodal imaging of multiple evanescent white dot syndrome.

The integrity of macular morphology was examined in a patient with multiple evanescent white dot syndrome (MEWDS) diagnosed through clinical and investigational adaptive optics (AO) retinal imaging techniques. Imaging was performed during the acute and recovery phases to examine changes in retinal morphology, revealing characteristic small multifocal white dots in the perifoveal region and a granular appearance in the fovea. Fluorescein angiography revealed early and intermediate hyperfluorescence, and regions of decreased fundus autofluorescence were observed.

Chronic retinal necrosis: cytomegalovirus necrotizing retinitis associated with panretinal vasculopathy in non-HIV patients.

Purpose: To characterize a unique cytomegalovirus (CMV)-associated retinopathy in patients with limited immune dysfunction.

Methods: Retrospective observational case series. CMV was confirmed as the pathogenic agent via polymerase chain reaction analysis of aqueous or vitreous humor samples or via immunohistochemical analysis of retinal biopsy specimens.

Retinal optical coherence tomography image enhancement via shrinkage denoising using double-density dual-tree complex wavelet transform.

ABSTRACT. Image enhancement of retinal structures, in optical coherence tomography (OCT) scans through denoising, has the potential to aid in the diagnosis of several eye diseases. In this paper, a locally adaptive denoising algorithm using double-density dual-tree complex wavelet transform, a combination of the double-density wavelet transform and the dual-tree complex wavelet transform, is applied to reduce speckle noise in OCT images of the retina.

The heritability of macular response to supplemental lutein and zeaxanthin: a classic twin study.

Purpose: Antioxidant supplements may reduce age-related macular degeneration (AMD) progression. The macular carotenoids are of particular interest because of their biochemical, optical, and anatomic properties. This classic twin study was designed to determine the heritability of macular pigment (MP) augmentation in response to supplemental lutein (L) and zeaxanthin (Z).

Preventive effects of ethyl pyruvate on endotoxin-induced uveitis in rats.

Purpose: Recent studies indicate that ethyl pyruvate (EP) exerts anti-inflammatory properties; however, the effect of EP on ocular inflammation is not known. The efficacy of EP in endotoxin-induced uveitis (EIU) in rats was investigated.

Methods: EIU in Lewis rats was developed by the subcutaneous injection of lipopolysaccharide (LPS; 150 μg).

Post-translational protein modification by carotenoid cleavage products.

Carotenoids are known to generate various aldehydes, known as carotenoid-derived aldehydes (CDAs), which could efficiently react with protein or DNA. In this in vitro model study, interaction between CDA and protein has been studied. Various proteins were incubated with CDA, and protein modification and adduct formation were confirmed by using matrix-assisted laser desorption and ionization time-of-flight, amino acid analysis, and measuring enzyme activity on modification with CDA.

Prevention of endotoxin-induced uveitis in rats by plant sterol guggulsterone.

Purpose: To investigate the anti-inflammatory effects of guggulsterone, an antioxidant and antitumor agent, in endotoxin-induced uveitis (EIU) in rats and to elucidate the underlying molecular mechanism or mechanisms related to ocular inflammation.

Methods: EIU was induced by subcutaneous injection of lipopolysaccharide (LPS; 150 μg) into Lewis rats treated with guggulsterone (30 mg/kg body weight, intraperitoneally) or its carrier. After 24 hours the rats were killed, eyes were enucleated, and aqueous humor (AqH) was collected.

Cadmium-induced induction of cell death in human lens epithelial cells: implications to smoking associated cataractogenesis.

Cadmium is reported to accumulate in human eye tissues suggesting its implication in diverse ocular pathology. Using an in vitro cell culture model we investigated the effects of cadmium on human lens epithelial cells (HLECs) (HLE-B3). We observed cadmium-induced dose- as well as time-dependent decline in HLECs viability which was exacerbated significantly upon reduction of intracellular glutathione levels by buthionine sulfoximine (BSO).

The value of measurement of macular carotenoid pigment optical densities and distributions in age-related macular degeneration and other retinal disorders.

There is increasing recognition that the optical and antioxidant properties of the xanthophyll carotenoids lutein and zeaxanthin play an important role in maintaining the health and function of the human macula. In this review article, we assess the value of non-invasive quantification of macular pigment levels and distributions to identify individuals potentially at risk for visual disability or catastrophic vision loss from age-related macular degeneration, and we consider the strengths and weaknesses of the diverse measurement methods currently available.

Genotoxic effects of carotenoid breakdown products in human retinal pigment epithelial cells.

Purpose: To investigate the genotoxic effects of lutein (LBP) and beta -carotene breakdown products (beta -apo-8-carotenal, BA8C) and the preventive role of GSH in human retinal pigment epithelial cells (ARPE-19).

Methods: LBP- and BA8C-induced DNA damage in human retinal pigment epithelial cells (ARPE-19) was determined by comet assay. The DNA damage was quantified by the image analysis system using Comet Score software.

Cadmium-induced apoptotic death of human retinal pigment epithelial cells is mediated by MAPK pathway.

Cadmium (Cd), released from cigarette smoke and metal industrial activities, is known to accumulate in human body organs including retina and is particularly higher in retinal tissues of age-related macular degeneration (AMD) eyes compared to non-AMD eyes. We have determined the cytotoxic effects of Cd on human retinal pigment epithelial (RPE) cells. Upon Cd treatment, there was a dose- and time-dependent decline in ARPE-19 cell viability as well as early apoptotic changes such as altered mitochondrial membrane potential (MMP) and Cytochrome C release in cytosol.

Prevention of posterior capsular opacification through aldose reductase inhibition.

Purpose: The purpose of this study was to evaluate the effect of aldose reductase (AR) inhibition on posterior capsular opacification (PCO) with the use of a pig eye capsular bag model.

Methods: Pig eye capsular bags were prepared by capsulorhexis and cultured in medium without or with AR inhibitors for 7 days. Immunostaining was performed in paraformaldehyde-fixed capsular bags to determine the expression of proliferating cell nuclear antigen (PCNA), alpha-smooth muscle actin (SMA), beta-crystallin, and intercellular adhesion molecule (ICAM)-1.