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Eye (London, England) May 2018The regional susceptibility of the retina to diseases has been well known by clinicians for many years. It is surprising that the implications of these observations have... (Review)
Review
The regional susceptibility of the retina to diseases has been well known by clinicians for many years. It is surprising that the implications of these observations have not spawned major research efforts to characterise the structural and functional attributes of the outer retina in different regions of a foveate retina. Without such an effort, the understanding of the disease mechanisms in retinal dystrophies will remain limited and may hamper therapeutic efforts. That outer retinal disease is responsible for over 50% of blind registration in the western world underlines the importance of these considerations.
Topics: Humans; Macula Lutea; Retinal Diseases
PubMed: 29148528
DOI: 10.1038/eye.2017.247 -
Ophthalmic Surgery, Lasers & Imaging... Oct 2018Vital dyes contain complex molecules with chromophores that stain living tissues and have greatly enhanced identification and removal of transparent vitreoretinal... (Review)
Review
Vital dyes contain complex molecules with chromophores that stain living tissues and have greatly enhanced identification and removal of transparent vitreoretinal tissues during surgery. Several "chromovitrectomy" dyes are frequently used by vitreoretinal specialists, including indocyanine green, trypan blue, brilliant blue G, and triamcinolone acetonide; other dyes are also under investigation. Trypan Blue was approved by the U.S. Food and Drug Administration (FDA) for epiretinal membrane removal, and preservative-free triamcinolone acetonide was approved by the FDA for intraocular use. However, currently available chromovitrectomy dyes have their limitations, and of particular concern for some of them is the possibility for acute and chronic toxicity to the neurosensory retina and retinal pigmented epithelium. The potentially irreversible acute toxicity and other limitations, such as lack of long-term safety profiles, highlight the need for further advancements. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:788-798.].
Topics: Coloring Agents; Humans; Indocyanine Green; Intraoperative Period; Macula Lutea; Retinal Diseases; Trypan Blue; Vitreoretinal Surgery; Vitreous Body
PubMed: 30395665
DOI: 10.3928/23258160-20181002-07 -
Eye (London, England) Oct 2021To evaluate the distribution of macula and circumpapillary retina nerve fiber layer (cpRNFL) thickness and other associated factors among grade-1 primary school children...
OBJECTIVE
To evaluate the distribution of macula and circumpapillary retina nerve fiber layer (cpRNFL) thickness and other associated factors among grade-1 primary school children in Lhasa using spectral-domain optical coherence tomography (SD-OCT).
METHODOLOGY
OCT assessment was conducted on 1856 grade-1 students from 7 primary schools in Lhasa, Tibet following a successful random stratified sampling of the students. Each child underwent comprehensive general and ocular examinations as well as an SD-OCT detection (12 × 9 mm, 3D wide scan mode, Topcon 3D OCT-1) to assess the thickness of the macula, ganglion cell-inner plexiform layer (GCIPL), ganglion cell complex (GCC), and cpRNFL. Multivariate and correlation analyses were performed to evaluate the association of the demographic and ocular variables.
RESULTS
The average age of the 1762 (94.43%) students who underwent OCT assessment was 6.83 ± 0.46 years. Among them, 984 (53.02%) were boys. The number of students who had macular, cpRNFL, and optic disc scans completed and with adequate image quality were 1412 (82.2%), 1277 (74.4%), and 1243 (72.4%), respectively. The average macula full retinal thickness (FRT), GCIPL, GCC, and cpRNFL thickness of the students was 279.19 ± 10.61 μm, 76.41 ± 4.70 μm, 108.15 ± 6.15 μm, and 112.33 ± 13.5 μm, respectively. Multivariate regression and correlation analysis further revealed that boys and girls had significant differences in their average cpRNFL thickness. Moreover, GCC and GCIPL thickness was negatively correlated with IOP but positively correlated with the body mass index. The thickness of all the layers of the macula and cpRNFL were positively correlated with spherical equivalent. Further to this, the average macular FRT, GCIPL, and GCC thicknesses were positively correlated with cpRNFL global thickness.
CONCLUSION
This study describes the normal distribution of macular retina, cpRNFL, and optic disc parameters in grade-1 Tibetan children in Lhasa. It contributes to the establishment of a normative ophthalmology database of Tibetan children, and advances the ability of OCT in ophthalmic disorder diagnosis during long-term monitoring in plateau.
Topics: Child; Cross-Sectional Studies; Female; Humans; Macula Lutea; Male; Nerve Fibers; Optic Disk; Retina; Retinal Ganglion Cells; Tomography, Optical Coherence
PubMed: 33239762
DOI: 10.1038/s41433-020-01313-z -
The Journal of General Physiology May 1955The iodopsin system found in the cones of the chicken retina is identical with the rhodopsin system in its carotenoids. It differs only in the protein-the opsin -with...
The iodopsin system found in the cones of the chicken retina is identical with the rhodopsin system in its carotenoids. It differs only in the protein-the opsin -with which carotenoid combines. The cone protein may be called photopsin to distinguish it from the scotopsins of the rods. Iodopsin bleaches in the light to a mixture of photopsin and all-trans retinene. The latter is reduced by alcohol dehydrogenase and cozymase to all-trans vitamin A(1). Iodopsin is resynthesized from photopsin and a cis isomer of vitamin A, neovitamin Ab or the corresponding neoretinene b, the same isomer that forms rhodopsin. The synthesis of iodopsin from photopsin and neoretinene b is a spontaneous reaction. A second cis retinene, isoretinene a, forms iso-iodopsin (lambda(max) 510 mmicro). The bleaching of iodopsin in moderate light is a first-order reaction (Bliss). The synthesis of iodopsin from neoretinene b and opsin is second-order, like that of rhodopsin, but is very much more rapid. At 10 degrees C. the velocity constant for iodopsin synthesis is 527 times that for rhodopsin synthesis. Whereas rhodopsin is reasonably stable in solution from pH 4-9, iodopsin is stable only at pH 5-7, and decays rapidly at more acid or alkaline reactions. The sulfhydryl poison, p-chloromercuribenzoate, blocks the synthesis of iodopsin, as of rhodopsin. It also bleaches iodopsin in concentrations which do not attack rhodopsin. Hydroxylamine also bleaches iodopsin, yet does not poison its synthesis. Hydroxylamine acts by competing with the opsins for retinene. It competes successfully with chicken, cattle, or frog scotopsin, and hence blocks rhodopsin synthesis; but it is less efficient than photopsin in trapping retinene, and hence does not block iodopsin synthesis. Though iodopsin has not yet been prepared in pure form, its absorption spectrum has been computed by two independent procedures. This exhibits an alpha-band with lambda(max) 562 mmicro, a minimum at about 435 mmicro, and a small beta-band in the near ultraviolet at about 370 mmicro. The low concentration of iodopsin in the cones explains to a first approximation their high threshold, and hence their status as organs of daylight vision. The relatively rapid synthesis of iodopsin compared with rhodopsin parallels the relatively rapid dark adaptation of cones compared with rods. A theoretical relation is derived which links the logarithm of the visual sensitivity with the concentration of visual pigment in the rods and cones. Plotted in these terms, the course of rod and cone dark adaptation resembles closely the synthesis of rhodopsin and iodopsin in solution. The spectral sensitivities of rod and cone vision, and hence the Purkinje phenomenon, have their source in the absorption spectra of rhodopsin and iodopsin. In the chicken, for which only rough spectral sensitivity measurements are available, this relation can be demonstrated only approximately. In the pigeon the scotopic sensitivity matches the spectrum of rhodopsin; but the photopic sensitivity is displaced toward the red, largely or wholly through the filtering action of the colored oil globules in the pigeon cones. In cats, guinea pigs, snakes, and frogs, in which no such colored ocular structures intervene, the scotopic and photopic sensitivities match quantitatively the absorption spectra of rhodopsin and iodopsin. In man the scotopic sensitivity matches the absorption spectrum of rhodopsin; but the photopic sensitivity, when not distorted by the yellow pigmentations of the lens and macula lutea, lies at shorter wave lengths than iodopsin. This discrepancy is expected, for the human photopic sensitivity represents a composite of at least three classes of cone concerned with color vision.
Topics: Animals; Cats; Cattle; Chickens; Eye Proteins; Guinea Pigs; Retina; Retinal Cone Photoreceptor Cells; Retinal Pigments; Retinaldehyde; Rhodopsin; Rod Opsins
PubMed: 14367777
DOI: 10.1085/jgp.38.5.623 -
Indian Journal of Ophthalmology Mar 2020
Topics: Female; Humans; Macula Lutea; Middle Aged; Retinal Perforations; Tomography, Optical Coherence
PubMed: 32057023
DOI: 10.4103/ijo.IJO_1425_19 -
Asia-Pacific Journal of Ophthalmology... 2019The process of emmetropization is the adjustment of the length of the optical axis to the given optical properties of the cornea and lens after the end of the second... (Review)
Review
The process of emmetropization is the adjustment of the length of the optical axis to the given optical properties of the cornea and lens after the end of the second year of life. Up to the end of the second year of life, the eye grows spherically. Axial elongation in the process of emmetropization after the second year of life is associated with a thinning of the retina and a reduced density of retinal pigment epithelium (RPE) cells in the equatorial and retroequatorial region, and a thinning of the choroid and sclera, starting at the equator and being most marked at the posterior pole. In contrast, retinal thickness and RPE density in the macular region and thickness of Bruch membrane (BM) in any region are independent of axial length. It led to the hypothesis that axial elongation occurs by the production of additional BM in the equatorial and retroequatorial region leading to a decreased RPE density and retinal thinning in that region and a more tube-like than spherical enlargement of the globe, without compromise in the density of the macular RPE cells and in macular retinal thickness. The increased disc-fovea distance in axially myopic eyes is caused by the development and enlargement of parapapillary, BM-free, gamma zone, whereas the length of macular BM, and indirectly macular RPE cell density, and macular retinal thickness, remain constant.
Topics: Axial Length, Eye; Bruch Membrane; Disease Progression; Humans; Macula Lutea; Myopia; Optic Disk
PubMed: 31425168
DOI: 10.1097/01.APO.0000578944.25956.8b -
Translational Vision Science &... Apr 2021We evaluated the patient-control differences and predictive value of the retina as potential biomarkers for schizophrenia.
PURPOSE
We evaluated the patient-control differences and predictive value of the retina as potential biomarkers for schizophrenia.
METHODS
The institutional study included both eyes of 58 schizophrenia spectrum disorder (SSD) patients (age 37.2 ± 12.3 years) and 35 controls (age 41.1 ± 15.2 years). Retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer, outer retinal photoreceptor complex, and total macula thicknesses were measured by optical coherence tomography (OCT). Anterior segment parameters including central corneal thickness, anterior chamber depth, and axial length were measured to rule out confounds on the retinal measures.
RESULTS
The peripapillary RNFL was overall significantly thinner in SSD relative to controls (F = 3.97, P = 0.049), most pronounced in the temporal (5.2 µm difference, F = 6.95, P = 0.010) and inferior quadrants (12.1 µm difference, F = 7.32, P = 0.009). There were no significant group differences in thickness for the macular RNFL, ganglion, or photoreceptor cell related measures (P > 0.05). Peripapillary RNFL, central macula, and outer photoreceptor complex thicknesses were together able to classify SSD patients with 80% sensitivity and 71% specificity; area under the curve = 0.82 (95% confidence interval, 0.75-0.88).
CONCLUSIONS
SSD patients exhibited significant RNFL thinning relative to controls. Notably, retinal thickness measures including both peripapillary and macular data exhibited improved diagnostic accuracy for SSD as compared to these regions alone.
TRANSLATIONAL RELEVANCE
This is the first study to evaluate the predictive value of both the inner and outer retina in SSD. OCT retinal thickness measures including peripapillary data in conjunction with macular data may provide an informative, noninvasive in vivo ocular biomarker for schizophrenia.
Topics: Adult; Biomarkers; Humans; Macula Lutea; Middle Aged; Nerve Fibers; Retinal Ganglion Cells; Schizophrenia; Tomography, Optical Coherence; Young Adult
PubMed: 34004009
DOI: 10.1167/tvst.10.4.29 -
Investigative Ophthalmology & Visual... May 2016Retinal photocoagulation and nondamaging laser therapy are used for treatment of macular disorders, without understanding of the response mechanism and with no rationale...
PURPOSE
Retinal photocoagulation and nondamaging laser therapy are used for treatment of macular disorders, without understanding of the response mechanism and with no rationale for dosimetry. To establish a proper titration algorithm, we measured the range of tissue response and damage threshold. We then evaluated safety and efficacy of nondamaging retinal therapy (NRT) based on this algorithm for chronic central serous chorioretinopathy (CSCR) and macular telangiectasia (MacTel).
METHODS
Retinal response to laser treatment below damage threshold was assessed in pigmented rabbits by expression of the heat shock protein HSP70 and glial fibrillary acidic protein (GFAP). Energy was adjusted relative to visible titration using the Endpoint Management (EpM) algorithm. In clinical studies, 21 eyes with CSCR and 10 eyes with MacTel were treated at 30% EpM energy with high spot density (0.25-diameter spacing). Visual acuity, retinal and choroidal thickness, and subretinal fluid were monitored for 1 year.
RESULTS
At 25% EpM energy and higher, HSP70 was expressed acutely in RPE, and GFAP upregulation in Müller cells was observed at 1 month. Damage appeared starting at 40% setting. Subretinal fluid resolved completely in 81% and partially in 19% of the CSCR patients, and visual acuity improved by 12 ± 3 letters. Lacunae in the majority of MacTel patients decreased while preserving the retinal thickness, and vision improved by 10 letters.
CONCLUSIONS
Heat shock protein expression in response to hyperthermia helps define the therapeutic window for NRT. Lack of tissue damage enables high-density treatment to boost clinical efficacy, therapy in the fovea, and retreatments to manage chronic diseases.
Topics: Animals; Disease Models, Animal; Finite Element Analysis; Fluorescein Angiography; Follow-Up Studies; Fundus Oculi; HSP72 Heat-Shock Proteins; Humans; Immunohistochemistry; Laser Therapy; Macula Lutea; Macular Degeneration; Male; Middle Aged; Prospective Studies; Rabbits; Time Factors; Tomography, Optical Coherence; Treatment Outcome; Visual Acuity
PubMed: 27159441
DOI: 10.1167/iovs.15-18981 -
Investigative Ophthalmology & Visual... Mar 2024A progression sequence for age-related macular degeneration onset may be determinable with consensus neuroanatomical nomenclature augmented by drusen biology and... (Review)
Review
A progression sequence for age-related macular degeneration onset may be determinable with consensus neuroanatomical nomenclature augmented by drusen biology and eye-tracked clinical imaging. This narrative review proposes to supplement the Early Treatment of Diabetic Retinopathy Study (sETDRS) grid with a ring to capture high rod densities. Published photoreceptor and retinal pigment epithelium (RPE) densities in flat mounted aged-normal donor eyes were recomputed for sETDRS rings including near-periphery rich in rods and cumulatively for circular fovea-centered regions. Literature was reviewed for tissue-level studies of aging outer retina, population-level epidemiology studies regionally assessing risk, vision studies regionally assessing rod-mediated dark adaptation (RMDA), and impact of atrophy on photopic visual acuity. The 3 mm-diameter xanthophyll-rich macula lutea is rod-dominant and loses rods in aging whereas cone and RPE numbers are relatively stable. Across layers, the largest aging effects are accumulation of lipids prominent in drusen, loss of choriocapillary coverage of Bruch's membrane, and loss of rods. Epidemiology shows maximal risk for drusen-related progression in the central subfield with only one third of this risk level in the inner ring. RMDA studies report greatest slowing at the perimeter of this high-risk area. Vision declines precipitously when the cone-rich central subfield is invaded by geographic atrophy. Lifelong sustenance of foveal cone vision within the macula lutea leads to vulnerability in late adulthood that especially impacts rods at its perimeter. Adherence to an sETDRS grid and outer retinal cell populations within it will help dissect mechanisms, prioritize research, and assist in selecting patients for emerging treatments.
Topics: Humans; Adult; Aged; Macular Degeneration; Retina; Macula Lutea; Geographic Atrophy; Retinal Cone Photoreceptor Cells
PubMed: 38466281
DOI: 10.1167/iovs.65.3.4 -
PloS One 2020We sought to evaluate the incidence and characteristics of dome-shaped macula (DSM) in children and adolescents with myopia.
PURPOSE
We sought to evaluate the incidence and characteristics of dome-shaped macula (DSM) in children and adolescents with myopia.
METHODS
A retrospective review of medical records was performed to identify subjects who were younger than 19 years with myopia of -3.0 diopters or greater. The results of optical coherence tomography images were analyzed to identify DSM. The height and diameter of the dome were measured. Age, best-corrected visual acuity (BCVA), and refractive error of study participants who exhibited DSM were compared with those of patients who did not.
RESULTS
Among the 1,042 eyes of 615 patients, eight eyes (0.77%) of seven patients had DSM. Six of these eight eyes were not highly myopic (i.e., less than -6.0 diopters of spherical equivalents). Additionally, the mean height and diameter of the identified domes were 146.50 ± 42.33 μm and 4779.75 ± 699.38 μm, respectively. Patients with DSM were significantly older (mean age: 15.88 ± 2.36 years) than patients without it (11.51 ± 4.60 years; p = 0.007). The youngest affected patient was 11 years old. There was no significant difference in refractive errors (p = 0.629) or BCVA (p = 0.314) between the two groups.
CONCLUSIONS
Although the incidence in this study was very low, DSM was found even in children and adolescents. In addition, 75% of affected individuals were not highly myopic. These results suggest that inherent traits may be involved in development of DSM.
Topics: Adolescent; Child; Child, Preschool; Disease Progression; Female; Fluorescein Angiography; Humans; Macula Lutea; Male; Myopia; Retrospective Studies; Tomography, Optical Coherence
PubMed: 31910232
DOI: 10.1371/journal.pone.0227292