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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 -
Applied Optics Oct 2015Optical design and testing have numerous applications in industrial, military, consumer, and bio-medical settings. This issue features original research ranging from the...
Optical design and testing have numerous applications in industrial, military, consumer, and bio-medical settings. This issue features original research ranging from the optical design of image and nonimage optical stimuli for human perception, optics applications, bio-optics applications, displays, and solar energy systems to novel imaging modalities from deep UV to infrared spectral imaging, a systems perspective to imaging, as well as optical measurement. In addition, new concepts and trends for optics and further optical systems will be especially highlighted in this special issue.
Topics: Equipment Design; Eye; Humans; Lasers; Light; Optical Devices; Optics and Photonics; Temperature
PubMed: 26479674
DOI: 10.1364/AO.54.00ODT1 -
Journal of Neuro-ophthalmology : the... Sep 2014Spectral-domain optical coherence tomography (SD-OCT) changed 3 worlds: clinical care, clinical research, and the regulatory environment of phases 2, 3, and 4... (Review)
Review
Spectral-domain optical coherence tomography (SD-OCT) changed 3 worlds: clinical care, clinical research, and the regulatory environment of phases 2, 3, and 4 pharmaceutical and surgical trials. OCT is now undergoing another transformation with multicolor technology, which acquires images using data from 3 simultaneous lasers: red, green, and blue, taking advantage of the different wavelengths of each of these colors to most precisely image 3 different zones of the retina. Rather than seeing only the surface of the retina and optic disc and any large lesions in the deeper retina, this technology provides a topographic map of the outer (red), mid (green), and inner (blue) retina somewhat similar to what is observed with fundus autoflourescence of deep retina, retinal pigment epithelium, and choroid. Multicolor imaging will supplement and help to define what is observed with traditional fundus photography and SD-OCT. In addition, it may demonstrate abnormalities when routine photography is normal and when SD-OCT findings are equivocal. This review will illustrate the basic principles of multicolor imaging and will show clinical examples of how this technique can further define retinal and optic nerve pathology.
Topics: Diagnostic Techniques, Ophthalmological; Fluorescein Angiography; Humans; Optic Disk; Retina; Retinal Pigment Epithelium; Tomography, Optical Coherence; Visual Pathways
PubMed: 25133967
DOI: 10.1097/WNO.0000000000000164 -
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 -
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 -
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 -
Journal of Cataract and Refractive... Jul 2022To compare axial length (AL) measurements obtained by optical biometry (OB) and immersion ultrasound (iUS) to investigate the agreement between the 2 techniques and how...
PURPOSE
To compare axial length (AL) measurements obtained by optical biometry (OB) and immersion ultrasound (iUS) to investigate the agreement between the 2 techniques and how to use OB constants for eyes with AL by iUS.
SETTING
Multicenter study.
DESIGN
Retrospective observational case series.
METHODS
Agreement between OB and iUS ALs was investigated in 4 subsets. Also, in a test database, the prediction error (PE) for iUS AL was assessed with 4 methods: (1) data-optimized constants; (2) user group for laser interference biometry (ULIB) constants with iUS biometry; (3) with recalibrated AL; and (4) ULIB A-constant - 0.23.
RESULTS
A Combined 1970 eyes were measured with both OB and iUS biometry. OB mean AL was 0.0873 mm longer than iUS AL. The latter was made equivalent to OB ALs with this equation: Recalibrated iUS AL = 1.0228 × iUS AL - 0.4556. In a fifth database (n = 1079) with OB AL measurements only, after AL was artificially shortened by 0.0873 mm, the original A-constant had to be reduced by 0.23 to maintain a zero PE. In a sixth database (n = 127) with iUS AL, the original ULIB A-constant provided the poorest outcomes. Using either recalibrated iUS AL or ULIB A-constant - 0.23 zeroed out the mean PE and achieved the lowest median absolute error.
CONCLUSIONS
AL measurements by iUS can be used with ULIB constants for OB by subtracting 0.23 from the A-constant; alternatively, the iUS AL may be recalibrated. The recalibrated iUS AL should be treated as AL measurements obtained by OB. It is longer than iUS AL in long eyes.
Topics: Axial Length, Eye; Biometry; Eye; Humans; Immersion; Lenses, Intraocular; Optics and Photonics; Refraction, Ocular; Retrospective Studies
PubMed: 34759175
DOI: 10.1097/j.jcrs.0000000000000865 -
Vestnik Oftalmologii 2022The article presents five cases of various forms of hemangiomas of the optic nerve head (ONH) and juxtapapillary retina that were monitored and analyzed using ocular...
The article presents five cases of various forms of hemangiomas of the optic nerve head (ONH) and juxtapapillary retina that were monitored and analyzed using ocular visualization methods. The obtained data allowed a conclusion that capillary hemangioma of the ONH features clearly-seen boundaries of the lesion both on ophthalmoscopy and optical coherence tomography (OCT) images; on the other hand, juxtapapillary granuloma can be characterized by blurred outlines on ophthalmoscopy and a gradual transition of the altered retina on OCT images with secondary changes seen in the macular area. When comorbid, capillary hemangioma of the ONH and retina feature a combination of these visualization signs.
Topics: Hemangioma, Capillary; Humans; Ophthalmoscopy; Optic Disk; Retina; Tomography, Optical Coherence
PubMed: 35488564
DOI: 10.17116/oftalma202213802166 -
Vestnik Oftalmologii 2020The review summarizes experimental and clinical data attesting to the important role the choroid plays in the development of refraction through optically oriented...
The review summarizes experimental and clinical data attesting to the important role the choroid plays in the development of refraction through optically oriented thickness changes and the release of growth factors. Because of its unique anatomical position, the choroid can influence the transmission of a cascade of chemical signals from the retina to the sclera and thereby affect the growth of the eye. Understanding the relationship between the optical defocus and the response of the choroid to it will help uncover the fundamental mechanisms for controlling eye growth and develop new strategies for preventing the progression of myopia.
Topics: Choroid; Disease Progression; Humans; Myopia; Retina; Sclera
PubMed: 32779466
DOI: 10.17116/oftalma2020136041124 -
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