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At least 667 records · Page 37Linked to original sources
PubMed2002

Retinal thickness in eyes with mild nonproliferative retinopathy in patients with type 2 diabetes mellitus: comparison of measurements obtained by retinal thickness analysis and optical coherence tomography.

OBJECTIVE: To compare measurements of retinal thickness in eyes with mild nonproliferative retinopathy in patients with type 2 diabetes mellitus using 2 different techniques: the retinal thickness analyzer (RTA) and optical coherence tomography (OCT). METHODS: Twenty-eight eyes from 28 patients with type 2 diabetes mellitus and mild nonproliferative retinopathy were classified according to the Wisconsin grading system by 7-field stereoscopic fundus photography. Ten eyes were classified as level 10 (absence of visible lesions) and 18 as level 20 or 35 (minimal retinopathy). All eyes were examined by the RTA and OCT. Healthy populations were used to establish reference maps for the RTA (n = 14; mean age, 48 years; age range, 42-55 years) and OCT (n = 10; mean age, 56 years; age range, 43-68 years). Reference maps were computed using the means + 2 SDs of the values obtained for each location. Increases in thickness were computed as a percentage of increase over these reference maps. RESULTS: The RTA detected increases in thickness in 1 or more locations in 24 of the 28 diabetic eyes examined, whereas OCT detected increases in only 3 eyes. The percentages of increase detected by the RTA ranged from 0.3% to 73.5%, whereas OCT detected percentages of increase of 0.3% to 4.8%. CONCLUSION: Optical coherence tomography is less sensitive than the RTA in detecting localized increases in retinal thickness in the initial stages of diabetic retinal disease.

Aged↗
PubMed1984

Retinal location in purple membrane of Halobacterium halobium: a neutron diffraction study of membranes labelled in vivo with deuterated retinal.

Purple membranes were prepared by growing Halobacterium halobium in a medium containing nicotine (which inhibits biosynthesis of retinal) and the oxidation products of fully deuterated beta-carotene. This allowed the in vivo incorporation of deuterated retinal into the membranes. The labelled membranes were crystalline and isomorphous with native membrane as determined by X-ray diffraction, and their optical absorption spectra were very similar. Neutron diffraction data for the two dimensional in-plane lattice from labelled and native membranes were analysed by difference Fourier and direct methods to 8.6 A resolution. The difference Fourier shows the retinal to be located in the centre of the bacteriorhodopsin molecule. The best fit to the data was obtained with the projection of retinal as a 10 A long rod forming an angle of -40 degrees +/- 10 degrees with the x axis centred at x = -0.19 +/- 0.02, y = -0.35 +/- 0.02 in fractional unit cell coordinates. The main peak in the difference Fourier map is at x = -0.17, y = -0.33.

Bacteriorhodopsins↗
PubMed2002

Neural cell differentiation from retinal pigment epithelial cells of the newt: an organ culture model for the urodele retinal regeneration.

Transdifferentiation from retinal pigment epithelium (RPE) to neural retina (NR) was studied under a new culture system as an experimental model for newt retinal regeneration. Adult newt RPEs were organ cultured with surrounding connective tissues, such as the choroid and sclera, on a filter membrane. Around day 7 in vitro, lightly pigmented "neuron-like cells" with neuritic processes were found migrating out from the explant onto the filter membrane. Their number gradually increased day by day. BrdU-labeling study showed that RPE cells initiated to proliferate under the culture condition on day 4 in vitro, temporally correlating to the time course of retinal regeneration in vivo. Histological observations of cultured explants showed that proliferating RPE cells did not form the stratified structure typically observed in the NR but they rather migrated out from the explants. Neuronal differentiation was examined by immunohistochemical detection of various neuron-specific proteins; HPC-1 (syntaxin), GABA, serotonin, rhodopsin, and acetylated tubulin. Immunoreactive cells for these proteins always possessed fine and long neurite-like processes. Numerous lightly pigmented cells with neuron-like morphology showed HPC-1 immunoreactivity. Fibroblast growth factor-2 (FGF-2), known as a potent factor for the transdifferentiation of ocular tissues in various vertebrates, substantially increased the numbers of both neuron-like cells and HPC-1-like immunoreactive cells in a dose-dependent manner. These results indicate that our culture method ensures neural differentiation of newt RPE cells in vitro and provides, for the first time, a suitable in vitro experimental model system for studying tissue-intrinsic factors responsible for newt retinal regeneration.

Animals↗
PubMed1993

Distribution of microtubule-associated proteins (MAPs) in adult and embryonic mouse retinal explants: presence of the embryonic map, MAP5/1B, in regenerating adult retinal axons.

Microtubule-associated proteins (MAPs) are developmentally regulated proteins involved in microtubule polymerization and stabilization. We have asked whether MAPs in regenerating adult mouse retinal ganglion cell axons recapitulate the pattern of MAPs seen during development. Adult and Embryonic Day 15 (E15) mouse retinal segments were explanted onto laminin-coated coverslips and allowed to extend neurites in serum-free medium. Using a variety of monoclonal antibodies (Mabs), we stained adult and E15 explant cultures for early (MAP5) and late (MAP1, MAP2, MAP2a+b, tau) MAPs. Optic neurites growing from E15 explants were strongly immunoreactive for MAP5. Labeling was absent for MAP1 and MAP2a+b. Mabs to MAP2 and tau lightly stained axons and cell bodies, probably due to MAP2c and juvenile tau which are found in developing neurons. In adult explant cultures, both perikarya and axons were immunoreactive for MAP1. MAP2 and MAP2a+b labeled perikarya and fibers within the explant, and tau stained axons on the substrate. MAP5 immunoreactivity was intense in the adult explant cultures, labeling axons extending over the substrate and perikarya and dendrites in the explant in a pattern similar to that seen in E15 explants. In summary, adult retinal explants maintain their adult complement of MAPs, in showing high levels of MAP1, tau immunoreactivity restricted to neurites on the substrate, and MAP2 segregated into neurites and perikarya within the explant. The exception is MAP5 for which the pattern of immunoreactivity is similar in adult and E15 retinal explants.

Animals↗
PubMed1992

Immunocytochemical localization of retinal binding protein in the octopus retina: a shuttle protein for 11-cis retinal.

The cephalopod retina contains two photopigments that are spatially separated within the photoreceptors; rhodopsin, localized in the light-sensitive rhabdoms, and retinochrome, present in the myeloid bodies of the photoreceptor inner segments. In the light, the chromophore of retinochrome, all-trans retinal, is photoisomerized to 11-cis to form metaretinochrome. Metaretinochrome is believed to serve as a store for 11-cis retinal used in the regeneration or biosynthesis of rhodopsin. Previous studies suggest that a soluble retinal binding protein (RALBP) serves as a shuttle between retinochrome and rhodopsin, and, in the dark, may transport chromophore from the myeloid bodies to the rhabdoms. Our study supports this hypothesis and demonstrates that RALBP is in the correct cellular locations to function as a shuttle. Dark- and light-adapted octopus retinas were labeled with anti-RALBP using immunofluorescence and immunogold techniques. Our results showed that RALBP was distributed differently in the dark- and light-adapted retinas. Our most significant observation was that myeloid bodies from light-adapted retinas were more heavily labeled by anti-RALBP than myeloid bodies in dark-adapted retinas. The rhabdomeres, interphotoreceptor matrix, and inner limiting membrane were also labeled in both light and dark conditions. Based on these results and evidence from previous biochemical studies, we conclude that in the dark RALBP leaves the myeloid bodies and transports 11-cis retinal to the rhabdoms where chromophore exchange with metarhodopsin may occur.

Adaptation, Ocular↗
PubMed2005

A novel in vitro retinal differentiation model by co-culturing adult human bone marrow stem cells with retinal pigmented epithelium cells.

Human retinal pigment epithelium (HRPE) cells are important in maintaining the normal physiology within the neurosensory retina and photoreceptors. Recently, transplantation of HRPE has become a possible therapeutic approach for retinal degeneration. By negative immunoselection (CD45 and glycophorin A), in this study, we have isolated and cultivated adult human bone marrow stem cells (BMSCs) with multilineage differentiation potential. After a 2- to 4-week culture under chondrogenic, osteogenic, adipogenic, and hepatogenic induction medium, these BMSCs were found to differentiate into cartilage, bone, adipocyte, and hepatocyte-like cells, respectively. We also showed that these BMSCs could differentiate into neural precursor cells (nestin-positive) and mature neurons (MAP-2 and Tuj1-positive) following treatment of neural selection and induction medium for 1 month. Furthermore, the plasticity of BMSCs was confirmed by initiating their differentiation into retinal cells and photoreceptor lineages by co-culturing with HRPE cells. The latter system provides an ex vivo expansion model of culturing photoreceptors for the treatment of retinal degeneration diseases.

Bone Marrow Cells↗
PubMed2004

Zebrafish mosaic eyes is a novel FERM protein required for retinal lamination and retinal pigmented epithelial tight junction formation.

Polarization is a common feature of many types of cells, and we are beginning to understand how cells become polarized. The role of cell polarity in development and tissue morphogenesis, however, is much less well understood. Our previous analysis of the mosaic eyes (moe) mutations revealed that moe is required for retinal lamination and also suggested that zebrafish moe function is required in the retinal pigmented epithelium (RPE) for the proper localization of adjacent retinal cell divisions at the apical neuroepithelial surface. To understand the function of moe in the RPE, we cloned the moe locus and show that it encodes a novel FERM (for 4.1 protein, ezrin, radixin, moesin) domain-containing protein. Expression of moe in the eye, kidney, and brain reflects phenotypes found in moe(-) mutants, including RPE and retinal lamination defects, edema, and small or absent brain ventricles. We show that moe function is required for tight junction formation in the RPE. We suggest that moe may be a necessary component of the crumbs pathway that regulates apical cell polarity and also may play a role in photoreceptor morphogenesis.

Amino Acid Sequence↗
PubMed2004

Intraocular implantation of DNA-transfected retinal pigment epithelium cells: a new approach for analyzing molecular functions in the newt retinal regeneration.

Adult newts can regenerate their entire retinas, even after surgical removal of the neural retina (retinectomy), through transdifferentiation of the retinal pigment epithelium (RPE) cells. To develop a new experimental system for analyzing molecular functions during retinal regeneration of adult newts, we attempted to deliver a foreign gene into RPE cells of retina-less eye-cups in vitro. Here we used pCS2mt-GFP as a reporter construct, and selected Polyfect as a transfection reagent. DNA-transfection appeared to be restricted to the RPE cells of retina-less eye-cups and its efficiency was 0.1-0.2%. We tried to implant RPE-choroid tissue containing DNA-transfected RPE cells into the eye of a host animal. The tissue was placed into the posterior eye-chamber immediately after retinectomy so that the implanted RPE tissue was facing the cornea (i.e., normal orientation). The implant and host RPE regenerated one continuous hybrid neural retina. Ocular sections after 60 days of implantation showed that a small number of cells in the regenerating retina were intensely stained with an anti-GFP antibody. Some of those cells were believed to be retinal cells such as ganglion cells, amacrine cells and photoreceptors. The GFP-positive cells in the hybrid regenerating retina could represent clones derived from a single RPE cell. These results indicate that this experimental system could become useful in the study of adult newt retinal regeneration.

Animals↗
PubMed2006

Neural retinal regeneration in the anuran amphibian Xenopus laevis post-metamorphosis: transdifferentiation of retinal pigmented epithelium regenerates the neural retina.

In urodele amphibians like the newt, complete retina and lens regeneration occurs throughout their lives. In contrast, anuran amphibians retain this capacity only in the larval stage and quickly lose it during metamorphosis. It is believed that they are unable to regenerate these tissues after metamorphosis. However, contrary to this generally accepted notion, here we report that both the neural retina (NR) and lens regenerate following the surgical removal of these tissues in the anuran amphibian, Xenopus laevis, even in the mature animal. The NR regenerated both from the retinal pigment epithelial (RPE) cells by transdifferentiation and from the stem cells in the ciliary marginal zone (CMZ) by differentiation. In the early stage of NR regeneration (5-10 days post operation), RPE cells appeared to delaminate from the RPE layer and adhere to the remaining retinal vascular membrane. Thereafter, they underwent transdifferentiation to regenerate the NR layer. An in vitro culture study also revealed that RPE cells differentiated into neurons and that this was accelerated by the presence of FGF-2 and IGF-1. The source of the regenerating lens appeared to be remaining lens epithelium, suggesting that this is a kind of repair process rather than regeneration. Thus, we show for the first time that anuran amphibians retain the capacity for retinal regeneration after metamorphosis, similarly to urodeles, but that the mode of regeneration differs between the two orders. Our study provides a new tool for the molecular analysis of regulatory mechanisms involved in retinal and lens regeneration by providing an alternative animal model to the newt, the only other experimental model.

Animals↗
PubMed2000

Two secreted retinal factors regulate different stages of development of the outer blood-retinal barrier.

The retinal pigment epithelium (RPE) lies at the interface between the neural retina and the choriocapillaries where it forms a blood-retinal barrier. Like endothelial regions of the blood-brain barrier, the development of the RPE barrier is a gradual, multistep process. A culture model of chick RPE was used to study this development. The permeability of the tight junctions that limit diffusion between neighboring RPE cells was measured as the transepithelial electrical resistance (TER). Embryonic day 14 (E14) retinas were used to make a conditioned medium that lowered the permeability of cultured RPE. The TER of cultures prepared from E14 RPE was twice that of E7 RPE. In each culture, retinal conditioned medium increases the TER 2-2.5 fold. The active factors of conditioned medium that affected each culture had different physical properties. The factor that affected E7 was protease-resistant with a Mr<10 kDa, but the factor that affected E14 appeared to be a protein of approximately 49 kDa. Unlike the effect of astrocyte conditioned medium on endothelia, retinal conditioned medium did not act synergistically with cAMP. These data indicate that the chick retina, which lacks astrocytes, uses different diffusible factors to regulate different stages of tight junction development.

Adrenergic Agonists↗
PubMed2002

Retinal and extra-retinal contribution to position coding.

Though considerable effort has been expended on demonstrating the importance of extraretinal cues in distance perception (e.g. state of vergence), recent studies have shown that enriching the visual image brings about a decrease of perceptual underestimation of distance as observed otherwise, providing that contextual information is situated in the proximal space with regard to target position. The fact that a similar effect was observed when viewing monocularly was suggesting a prevalence of retinal input in distance coding. The present study, investigating reaching movements performed monocularly or binocularly in three successive visual scenes (dark-structured-dark), gave evidence for this assumption. Whatever the vision condition, a dark environment gave rise to an underestimation of target distance, which disappeared instantaneously when a structured background was unexpectedly provided. The sudden return to the dark condition resulted in a progressive drift towards underestimation. These findings strongly suggest that structured retinal information influences widely the perception of target distance. They show in addition that retinal signals may contribute to the calibration of non-retinal sources of information. The putative implication of the posterior parietal cortex in this dual influence is discussed.

Adult↗
PubMed2006

Reproducibility of peripapillary retinal nerve fiber layer and macular retinal thickness measurements using optical coherence tomography.

We investigated the interoperator reproducibility of peripapillary retinal nerve fiber layer (RNFL) and macular retinal thickness measurements using optical coherence tomography (OCT) in healthy Taiwanese eyes. In this study, OCT-3 was used by three trained and experienced operators to measure peripapillary RNFL and macular retinal thickness in a randomly chosen single eye from each normal subject. Mean thickness levels and the differences in thickness measurements among the three operators were calculated and compared. The eyes of 39 subjects (24 females and 15 males) were enrolled. The mean age of the subjects was 30.4 +/- 16.1 years (range, 11-46 years). The mean pupil diameter after pupillary dilation was 7.4 +/- 0.6mm (range, 6-9 mm). Comparing peripapillary RNFL and macular retinal thickness measurements after pupillary dilation, there were no significant differences in: superior, inferior, temporal, and nasal peripapillary areas; 6 mm total macular volume and foveal thickness; and 1, 3 and 6 mm perifoveal areas among the three operators. In this study, OCT thickness measurements showed good interoperator reproducibility among three trained and experienced operators.

Adolescent↗
PubMed1978

Specificity of the retinal binding site of bacteriorhodopsin: chemical and stereochemical requirements for the binding of retinol and retinal.

The complexes formed from bacteriopsin and various retinyl compounds were analyzed by fluorescence and absorption spectroscopy. The binding of retinol occurs in two steps. In the first reaction the molecule is fixed in the retinal binding site of the protein. In this state, energy transfer from aromatic amino acid residues to the retinyl moiety is observed. all-trans-Retinal and the 13-, 11-, and 9-cis-retinols are bound in the chromophoric site. In the second reaction the cyclohexene ring and the side chain of the retinyl moiety are forced into a planar conformation. This reaction is mediated by a base (B1) with a pK of 3.8 and requires the oxygen atom but not the free hydroxyl group of retinol, indicating interaction with a group AH (pK greater than or equal to 10.5). The ring-chain planarization reaction is blocked for the 9-cis isomer of retinol. Binding studies with bacterioopsin and retinal isomers reveal that, as in the case of the corresponding retinols, B1 mediates ring-chain planarization in the case of the all-trans, 13-cis, and 11-cis isomers but not with the 9-cis isomer. Reconstitution of the purple complex from the intermediate 430-460-nm chromophore requires the presence of a second base (B2) with a pK of 4.6. This reaction is exclusive for all-trans- and 13-cis-retinal

Bacteriorhodopsins↗
PubMed1992

Neurolin, a cell surface glycoprotein on growing retinal axons in the goldfish visual system, is reexpressed during retinal axonal regeneration.

The mAb E 21 recognizes a cell surface glycoprotein selectively associated with fish retinal ganglion cell axons that are in a state of growth. All retinal axons and ganglion cells in goldfish embryos stained for E 21. In adult fish, however, E 21 immunoreactivity exhibited a patterned distribution in ganglion cells in the marginal growth zone of the continuously enlarging fish retina and the new axons emerging from these cells in the retina, optic nerve, and optic tract. The E 21 antigen was absent from older axons, except the terminal arbor layer in the tectum, the Stratum fibrosum et griseum superficiale where it was uniformly distributed. Upon optic nerve transection, the previously unlabeled axons reacquired E 21 positivity as they regenerated throughout their path to the tectum. Several months after ONS, however, E 21 staining disappeared from the regenerated axons over most of their lengths but reappeared as in normal fish in the terminal arbor layer. The immunoaffinity-purified E 21 antigen, called Neurolin, has an apparent molecular mass of 86 kD and contains the HNK1/L2 carbohydrate moiety, like several members of the class of cell adhesion molecules of the Ig superfamily. The NH2-terminal amino acid sequence has homologies to the cell adhesion molecule DM-Grasp recently described in the chicken. Thus, retinal ganglion cell axons express Neurolin during their development and are able to reexpress this candidate cell adhesion molecule during axonal regeneration, suggesting that Neurolin is functionally important for fish retinal axon growth.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed1975

Marked accommodation, retinal stretch, monocular space perception and retinal receptor orientation.

In recent years we have come to recognize that retinal receptors are probably aligned with the center of the exit pupil of the eye. It becomes crucial to define those factors influencing and determining photoreceptor alignment. Here, the effect of retinal stretch associated with marked accommodation has been considered. Assuming that a sense of direction is associated with a given retinal locus, we have used a classical monocular bisection test technique in order to see if marked accommodation altered bisection settings. Substantial changes in bisection settings were found when testing in the region of the posterior pole. These could be localized most probably in the retina and choroid. In separate studies, the effect of anterior retinal stretch upon cone receptor orientation in the region of the fovea was evaluated. Marked accommodation caused a transient nasal displacement of the peak of the Stiles-Crawford directional sensitivity function. These studies suggest that the posterior pole of the eye is routinely subject to stresses and strains. This point is of clinical significance. Our studies suggest that the presence of the blind spot influences the magnitude of change of measured parameters. We have only begun the important task of evaluating the nature of recovery processes following marked accommodation. Lastly, in order to obtain the necessary responses, we have had to train our young observers to voluntarily utilize nearly their entire accommodative capability.

Accommodation, Ocular↗
PubMed2006

Retinal thickness in diabetic retinopathy: comparison of optical coherence tomography, the retinal thickness analyzer, and fundus photography.

BACKGROUND: Optical coherence tomography (OCT) and the retinal thickness analyzer (RTA) have proved their ability to measure retinal thickness in healthy subjects and diabetics reliably. In the present study, both techniques were compared for the same study population of diabetic patients, and the findings were related to macular edema shown by stereo fundus photography (SFP). METHODS: Maculas of 124 eyes from 69 patients with diabetes mellitus were examined with OCT and the RTA. Measurements of retinal thickness were compared with signs of macular edema shown by SFP. For each eye, nine different sectors were analyzed (a foveal sector, four parafoveal sectors, and four extrafoveal sectors). Thirteen eyes with a normal macula served as controls. Sensitivity and specificity of detecting clinically significant macular edema (CSME) were calculated. RESULTS: Of 111 eyes, 64 showed signs of CSME by SFP. Mean retinal thickness +/- SD of the foveal sector was 249 +/- 104 microm by RTA and 295 +/- 124 microm by OCT measurements. There was a moderate overall correlation between OCT and the RTA (r = 0.66). The correlation was best in the foveal sector (r = 0.82). Overall correlation with SFP was better for OCT (r = 0.77) than for the RTA (r = 0.62). Sensitivity of detecting CSME was consistently higher with OCT, while the RTA showed higher specificity. CONCLUSION: Both measuring techniques yielded similar results when examining eyes of patients with diabetes, although absolute values differed. OCT seems to be more suitable in the clinical screening for macular edema due to its high sensitivity (>90%) with appropriate analysis parameters. The RTA is more prone to erroneous or missing thickness readings particularly under difficult measuring conditions.

Adolescent↗
PubMedDate not supplied

Evaluation of in vitro effects of bevacizumab (Avastin) on retinal pigment epithelial, neurosensory retinal, and microvascular endothelial cells.

PURPOSE: To evaluate the short-term in vitro safety of bevacizumab (Avastin) in human retinal pigment epithelial (ARPE-19), rat neurosensory retinal (R28), and human microvascular endothelial (HMVECad) cells. METHODS: ARPE-19 and R28 cells were treated with 0.125 mg/mL, 0.25 mg/mL, 0.50 mg/mL, and 1 mg/mL of bevacizumab for 2, 6, and 24 hours. HMVECad cells were treated with 5 ng/mL of vascular endothelial growth factor (VEGF) and 0.125 mg/mL, 0.25 mg/mL, 0.50 mg/mL, and 1 mg/mL of either bevacizumab for 2, 6, and 24 hours or a nonspecific human purified immunoglobulin (IgG) for 24 hours. Cell viability was measured using trypan blue dye exclusion assay. RESULTS: The cell viabilities of ARPE-19 cells, R28 cells, and HMVECad cells treated with bevacizumab were not significantly different (P > 0.05) from that of untreated controls. There was no significant difference (P > 0.05) between viabilities of HMVECad cells treated with bevacizumab and IgG. CONCLUSION: This study suggests that bevacizumab, at concentrations at or above the dose normally used in clinical practice, is not toxic to human retinal pigment epithelial, rat neurosensory retinal, or human microvascular endothelial cells in vitro. This report is consistent with the recent report of lack of toxicity of intravitreal bevacizumab in rabbits as well as the lack of apparent toxicity in clinical use.

Angiogenesis Inhibitors↗
PubMed2005

Retinal location of the preferred retinal locus relative to the fovea in scanning laser ophthalmoscope images.

PURPOSE: It is difficult to determine the position of a preferred retinal locus (PRL) relative to the fovea in scanning laser ophthalmoscope (SLO) images as a result of disease-related retinal morphologic changes that obscure the fovea. To overcome this problem, we developed a method for determining retinal foveal position based on normal fixation position relative to the optic disk. The normal foveal position measurements can then be used to estimate the distance between a PRL and the fovea. METHODS: Using the SLO, foveal position was determined for 50 normal subjects by measuring the retinal locus of fixation relative to the optic disk in undistorted SLO images. The resulting normal foveal fixation area is described by a bivariate normal ellipse that can be plotted on any undistorted SLO image. Measurement reliability was assessed by repeated measurements. The PRL relative to the normal foveal fixation area was determined for 24 subjects with macular degeneration and bilateral central scotomas. RESULTS: The normal foveal fixation area based on all 50 subjects is described by a p = 0.9 bivariate ellipse whose centroid is located 12.6 degrees temporal to the temporal optic disk edge and 1.4 degrees inferior to a horizontal line bisecting the disk. PRL area is shown to increase with distance from the foveal fixation ellipse centroid. The shape of the PRL, characterized by the ratio of PRL ellipse major to minor axis, was found to depend on whether the PRL was vertically or horizontally aligned with the foveal fixation centroid. CONCLUSIONS: PRL position relative to the fovea can be reliably estimated by plotting the normal foveal fixation bivariate ellipse on undistorted SLO images of retinas in which the fovea is obscured as a result of the disease process.

Adult↗