-
Experimental Biology and Medicine... Oct 2021By providing the sectioning capability to differentiate individual retinal layers, optical coherence tomography (OCT) is revolutionizing eye disease diagnosis and... (Review)
Review
By providing the sectioning capability to differentiate individual retinal layers, optical coherence tomography (OCT) is revolutionizing eye disease diagnosis and treatment evaluation. A better understanding of the hyper- and hypo-reflective bands in retinal OCT is essential for accurate interpretation of clinical outcomes. In this article, we summarize the interpretations of clinical OCT and adaptive optics (AO) OCT (AO-OCT) of the outer retina in the human eye, and briefly review OCT investigation of the outer retina in animal models. Quantitative analysis of outer retinal OCT bands is compared to established parameters of retinal histology. The literature review and comparative analysis support that both inner/outer segment (IS/OS) junction and IS ellipsoid zone nonexclusively contribute to the second band; and OS, OS tips, and retinal pigment epithelium apical processes contribute to the third band in conventional OCT. In contrast, AO-OCT might predominantly detect the IS/OS junction and OS tip signals at the second and third bands due to its improved sectioning capability and possible AO effect on the sensitivities for recording ballistic and diffusive photons from different regions of the outer retina.
Topics: Animals; Eye Diseases; Fovea Centralis; Humans; Photoreceptor Cells, Vertebrate; Ranidae; Retinal Pigment Epithelium; Tomography, Optical Coherence
PubMed: 34111984
DOI: 10.1177/15353702211022674 -
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 -
Turkish Journal of Ophthalmology Dec 2022Hamartomas are local malformation of cells that demonstrate abnormal proliferation in the area where they are normally present. Retinal and optic disc hamartomas include...
Hamartomas are local malformation of cells that demonstrate abnormal proliferation in the area where they are normally present. Retinal and optic disc hamartomas include astrocytic hamartoma, congenital hypertrophy of the retinal pigment epithelium (CHRPE), simple congenital hamartoma of the retinal pigment epithelium (CSHRPE), combined hamartoma of the retina and retinal pigment epithelium (CHRRPE), retinal hemangioblastoma (retinal capillary hemangioma), and retinal cavernous hemangioma. Retinal and optic disc hamartomas can be observed sporadically as well as with systemic associations. Astrocytic hamartoma usually appears as a flat, transparent yellowish lesion. CHRPE is a round, pigmented, and flat lesion. CSHRPE usually presents as a dark black macular tumor. CHRRPE consists of vascular, glial, and pigment epithelial components, which can demonstrate peripapillary, macular, and peripheral localization. Retinal hemangioblastoma is a vascular tumor, red-pink in color with tortuous and dilated afferent and efferent vessels, typically located in the peripheral retina or optic disc. Retinal cavernous hemangioma is characterized by the formation of thin-walled saccular angiomatous structures in the retina or optic nerve head resembling concord grapes. Ultrasonography, fundus autofluorescence, optical coherence tomography, optical coherence tomography angiography, and fluorescein angiography methods are used in the diagnosis of retinal and optic disc hamartomas. Some retinal and optic disc hamartomas do not require treatment. However, complications including vitreous hemorrhage, macular exudation, retinal detachment, macular hole, epiretinal membrane, and choroidal neovascularization require treatment.
Topics: Humans; Optic Disk; Hemangioblastoma; Retina; Retinal Diseases; Retinal Neoplasms; Eye Abnormalities; Hamartoma; Eye Neoplasms; Hemangioma, Cavernous
PubMed: 36578224
DOI: 10.4274/tjo.galenos.2022.25979 -
Clinical & Experimental Optometry Jan 2021Optical coherence tomography angiography (OCT-A) is a non-invasive imaging modality for assessing the vasculature within ocular structures including the retina, macula,... (Review)
Review
Optical coherence tomography angiography (OCT-A) is a non-invasive imaging modality for assessing the vasculature within ocular structures including the retina, macula, choroid and optic nerve. OCT-A has a wide range of clinical applications in various optometric conditions which have been independently reported in the literature. This paper aims to present a review of the current literature on the clinical application of OCT-A in optometric practice as well as to analyse and evaluate the quality of the available evidence. This review included 78 articles from a literature search conducted on 26 May 2019 across the following databases: Cochrane Library of Systematic Reviews, Medline, Scopus and Web of Science. Primary ocular pathologies discussed in this review include glaucoma, diabetic retinopathy, age-related macular degeneration, myopia, acquired and congenital macular dystrophies, epiretinal membrane, retinal vein occlusion, retinitis pigmentosa, choroidal melanoma, uveitis, central serous chorioretinopathy, amblyopia and optic neuropathies. Primary outcome variables included vessel density, foveal avascular zone area and diameter, flow velocity and flow index. This review aims to evaluate the evidence available for OCT-A applications in diagnosis and prognosis of ocular conditions in an optometric setting.
Topics: Fluorescein Angiography; Humans; Macula Lutea; Retina; Retinal Vessels; Systematic Reviews as Topic; Tomography, Optical Coherence
PubMed: 32285493
DOI: 10.1111/cxo.13068 -
Acta Ophthalmologica Dec 2022To determine the utility of Split-Window optical coherence tomography OCT (SW-OCT) biometry in measuring ocular axial dimensions as well as imaging the intraocular lens...
PURPOSE
To determine the utility of Split-Window optical coherence tomography OCT (SW-OCT) biometry in measuring ocular axial dimensions as well as imaging the intraocular lens (IOL) and posterior capsule in pseudophakic eyes.
METHODS
Sixty-nine pseudophakic eyes of 69 subjects were enrolled in the study. The results of SW-OCT biometry implemented in the SD OCT device for posterior and anterior segment imaging (REVO NX, Optopol Technology) were compared with those obtained with the SS-OCT-based biometer IOLMaster 700 (Carl Zeiss Meditec). Differences in measurement values between the two biometers were determined using the paired t-test. Agreement was assessed through intraclass correlation coefficients (ICC) and Bland-Altman plots.
RESULTS
The correlation between measurements obtained with SW-OCT and SS-OCT was very high (ICC for: axial length (AL) = 1.000; anterior chamber depth (ACD) = 0.997; IOL thickness (IOL LT) = 0.997; central corneal thickness (CCT) = 0.987). The mean AL measurement difference was 0.003 ± 0.021 mm (the 95% LoA ranged from -0.04 to 0.05); the mean ACD difference was -0.009 ± 0.025 mm (95% LoA, -0.06 to 0.04); mean LT difference was 0.001 ± 0.021 mm (95% LoA, -0.04 to 0.04); and mean CCT difference was 1.4 ± 5.4 μm (95% LoA, -9 to 12).
CONCLUSION
The study shows small, non-significant differences between the biometric measurements obtained with REVO NX SW-OCT and IOLMaster 700 SS-OCT in pseudophakic eyes. However, SW-OCT offered significantly lower ACD and LT measurement failure rates. With high-resolution imaging, SW-OCT enables accurate assessment of IOL position relative to the posterior capsule and visualization of capsular fibrosis.
Topics: Humans; Axial Length, Eye; Tomography, Optical Coherence; Reproducibility of Results; Biometry; Lenses, Intraocular; Anterior Chamber; Interferometry; Cornea
PubMed: 35670319
DOI: 10.1111/aos.15198 -
Annual Review of Vision Science Sep 2019Retinal function has long been studied with psychophysical methods in humans, whereas detailed functional studies of vision have been conducted mostly in animals owing... (Review)
Review
Retinal function has long been studied with psychophysical methods in humans, whereas detailed functional studies of vision have been conducted mostly in animals owing to the invasive nature of physiological approaches. There are exceptions to this generalization, for example, the electroretinogram. This review examines exciting recent advances using in vivo retinal imaging to understand the function of retinal neurons. In some cases, the methods have existed for years and are still being optimized. In others, new methods such as optophysiology are revealing novel patterns of retinal function in animal models that have the potential to change our understanding of the functional capacity of the retina. Together, the advances in retinal imaging mark an important milestone that shifts attention away from anatomy alone and begins to probe the function of healthy and diseased eyes.
Topics: Animals; Humans; Ophthalmoscopy; Optics and Photonics; Retina; Retinal Neurons; Tomography, Optical Coherence; Vision, Ocular
PubMed: 31525142
DOI: 10.1146/annurev-vision-091517-034239 -
ELife Sep 2023The telencephalon and eye in mammals are originated from adjacent fields at the anterior neural plate. Morphogenesis of these fields generates telencephalon,...
The telencephalon and eye in mammals are originated from adjacent fields at the anterior neural plate. Morphogenesis of these fields generates telencephalon, optic-stalk, optic-disc, and neuroretina along a spatial axis. How these telencephalic and ocular tissues are specified coordinately to ensure directional retinal ganglion cell (RGC) axon growth is unclear. Here, we report self-formation of human telencephalon-eye organoids comprising concentric zones of telencephalic, optic-stalk, optic-disc, and neuroretinal tissues along the center-periphery axis. Initially-differentiated RGCs grew axons towards and then along a path defined by adjacent PAX2+ VSX2+ optic-disc cells. Single-cell RNA sequencing of these organoids not only confirmed telencephalic and ocular identities but also identified expression signatures of early optic-disc, optic-stalk, and RGCs. These signatures were similar to those in human fetal retinas. Optic-disc cells in these organoids differentially expressed and ; FGFR inhibitions drastically decreased early RGC differentiation and directional axon growth. Through the RGC-specific cell-surface marker CNTN2 identified here, electrophysiologically excitable RGCs were isolated under a native condition. Our findings provide insight into the coordinated specification of early telencephalic and ocular tissues in humans and establish resources for studying RGC-related diseases such as glaucoma.
Topics: Animals; Humans; Retinal Ganglion Cells; Retina; Glaucoma; Axons; Telencephalon; Mammals
PubMed: 37665325
DOI: 10.7554/eLife.87306 -
Asia-Pacific Journal of Ophthalmology... Nov 2022The diagnosis of glaucoma depends upon indentification of characteristic damage to the optic nerve and retinal fiber layer. In many cases, however, clinicians find it...
The diagnosis of glaucoma depends upon indentification of characteristic damage to the optic nerve and retinal fiber layer. In many cases, however, clinicians find it difficult to ascertain whether glaucomatous damage is present or absent. These patients are often labeled as "glaucoma suspects," which creates a subpopulation of individuals without clear-cut disease who nonetheless must remain under surveillance. Most will never go on to develop glaucoma, yet the need for ongoing monitoring burdens clinics and health care systems. In this perspective, we illustrate possible directions and novel approaches that can be used to remedy this situation by integrating current technologies into clinical practice. In particular, we suggest that optical coherence tomography be better utilized to methodologically classify these eyes into glaucomatous and healthy categories.
Topics: Humans; Optic Disk; Nerve Fibers; Retinal Ganglion Cells; Intraocular Pressure; Ocular Hypertension; Glaucoma; Tomography, Optical Coherence
PubMed: 36278943
DOI: 10.1097/APO.0000000000000564 -
Journal of Vision Feb 2022Convolved images are often used to simulate the effect of ocular aberrations on image quality, where the retinal image is simulated by convolving the stimulus with the...
Convolved images are often used to simulate the effect of ocular aberrations on image quality, where the retinal image is simulated by convolving the stimulus with the point spread function derived from the subject's aberrations. However, some studies have shown that convolved images are perceived far more degraded than the same image blurred with optical defocus. We hypothesized that the positive interactions between the monochromatic and chromatic aberrations in the eye are lost in the convolution process. To test this hypothesis, we evaluated optical and visual quality with natural optics and with convolved images (on-bench, computer simulations, and visual acuity [VA] in subjects) using a polychromatic adaptive optics system with monochromatic (555 nm) and polychromatic light (WL) illumination. The subject's aberrations were measured using a Hartmann Shack system and were used to convolve the visual stimuli, using Fourier optics. The convolved images were seen through corrected optics. VA with convolved stimuli was lower than VA through natural aberrations, particularly in WL (by 26% in WL). Our results suggest that the systematic decrease in visual performance with visual acuity and retinal image quality by simulation with convolved stimuli appears to be primarily associated with a lack of favorable interaction between chromatic and monochromatic aberrations in the eye.
Topics: Humans; Optics and Photonics; Photic Stimulation; Retina; Vision, Ocular; Visual Acuity
PubMed: 35179553
DOI: 10.1167/jov.22.2.12 -
FASEB Journal : Official Publication of... Apr 2020The optics of the eye is the key to a functioning visual system. The exact nature of the correlation between ocular optics and eye development is not known because of...
The optics of the eye is the key to a functioning visual system. The exact nature of the correlation between ocular optics and eye development is not known because of the paucity of knowledge about the growth of a key optical element, the eye lens. The sophisticated optics of the lens and its gradient of refractive index provide the superior optical quality that the eye needs and which, it is thought, has a major influence on the development of proper visual function. The nature of a gradient refractive index lens, however, renders accurate measurements of its development difficult to make and has been the reason why the influence of lens growth on visual function remains largely unknown. Novel imaging techniques have made it possible to investigate growth of the eye lens in the zebrafish. This study shows measurements using X-ray Talbot interferometry of three-dimensional gradient index profiles in eye lenses of zebrafish from late larval to adult stages. The zebrafish lens shows evidence of a gradient of refractive index from the earliest stages measured and its growth suggests an apparent coincidence between periods of rapid increase in refractive index in the lens nucleus and increased expression of a particular crystallin protein group.
Topics: Animals; Cornea; Lens, Crystalline; Mathematical Computing; Optics and Photonics; Refractometry; Zebrafish
PubMed: 32103543
DOI: 10.1096/fj.201902607R