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The British Journal of Ophthalmology Oct 2019Myopic eyes have an increased risk of glaucoma. However, glaucomatous changes in a myopic eye are often difficult to detect. Classic structural and functional... (Review)
Review
Myopic eyes have an increased risk of glaucoma. However, glaucomatous changes in a myopic eye are often difficult to detect. Classic structural and functional investigations to diagnose glaucoma may be confounded by myopia. Here, we identify some of the common pitfalls in interpreting these structural parameters, and the possible solutions that could be taken to overcome them. For instance, in myopic eyes, we discuss the limitations and potential sources of error when using neuroretinal rim parameters, and retinal nerve fibre layer and ganglion cell-inner plexiform layer thickness measurements. In addition, we also review new developments and potential adjuncts in structural imaging such as the assessment of the retinal nerve fibre layer texture, and the examination of the microcirculation of the optic nerve head using optical coherence tomography angiography. For the functional assessment of glaucoma, we discuss perimetric strategies that may aid in detecting characteristic visual field defects in myopic glaucoma. Ultimately, the evaluation of glaucoma in myopia requires a multimodal approach, to allow correlation between structural and functional assessments. This review provides overview on how to navigate this diagnostic dilemma.
Topics: Fluorescein Angiography; Glaucoma; Humans; Microcirculation; Myopia; Nerve Fibers; Optic Disk; Retinal Ganglion Cells; Tomography, Optical Coherence; Vision Disorders; Visual Fields
PubMed: 31040131
DOI: 10.1136/bjophthalmol-2018-313530 -
Contact Lens & Anterior Eye : the... Aug 2022Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is... (Review)
Review
Optical Coherence Tomography (OCT) is a noninvasive, high-speed, high-resolution imaging technology based in the Michaelson interferometry. A near-infrared light beam is used to register the intensity variations for the light backscattered on each sample layer. Due to the high repeatability on corneal measurements, spectral domain OCT (SD-OCT) is the gold standard when talking about in vivo, non-invasive anterior segment imaging. Changes in the morphology of various ocular surfaces such as the cornea, conjunctiva, limbus or tear film with soft (SCL), rigid, corneal or scleral lens (SL) wear can be described by OCT measurements. For instance, evaluation of the corneoscleral region is essential on SL fitting. For orthokeratology lenses central epithelial thinning and peripheral thickening and their regression could be quantified with OCT after Ortho-K lens wear. Blood vessel compression on the landing zone as well as vault thickness and fluid reservoir (FR) turbidity could be imaged with OCT. Tear film evaluation on contact lens wearers is essential because its use could lead to variations on the biochemical components in tears. Changes in tear meniscus dynamics and several parameters such as volume (TMV), tear meniscus height (HMT) and turbidity could be determined with OCT and positively correlated with the instillation of different ophthalmic solutions with Non-Invasive Break Up Time (NIBUT) and Schirmer test values. This manuscript shows the increasing applicability of OCT technology for the in vivo characterization of contact lens fitting and interaction with the ocular surface in a faster, safer and non-invasive way. Future research will still allow exploring OCT imaging to its full potential in contact lens practice, as there is still a significant amount of information contained in the images that are not yet easy to extract, analyze and give clinical value.
Topics: Conjunctiva; Contact Lenses, Hydrophilic; Cornea; Humans; Tears; Tomography, Optical Coherence
PubMed: 34799247
DOI: 10.1016/j.clae.2021.101540 -
Retinal Cases & Brief Reports Jan 2024To report a case of peripapillary subretinal fluid associated with a ridge-shaped morphology surrounding the optic disk, which we termed ridge-shaped peripapilla.
PURPOSE
To report a case of peripapillary subretinal fluid associated with a ridge-shaped morphology surrounding the optic disk, which we termed ridge-shaped peripapilla.
METHODS
Case report.
RESULTS
A 6-year-old girl with mild-to-moderate myopia was referred for an abnormal fundus appearance of the left eye. Fundus examination of the left eye showed a vertical whitish elevation just temporal to the disk with pigment clumping. Spectral domain optical coherence tomography of the left eye showed an elevation of the fundus at the temporal edge of the disk with thinning of the choroid overlying the thickened scleral protrusion and a serous subretinal fluid. Fluorescein angiography of the left eye showed a hyperfluorescent area without leakage at the temporal edge of the disk, indicative of retinal pigment epithelium atrophy. There was no sign of choroidal neovascularization. Based on the fluorescein angiography and optical coherence tomography findings, the protrusion of the sclera seemed to result in overlying choroidal thinning with choroidal blood flow disturbances, and consequent retinal pigment epithelium atrophy, leading to the subretinal fluid.
CONCLUSION
This case highlights an unusual presentation of ridge-shaped peripapilla, characterized by inward convexity of the peripapillary area with a ridge-shaped morphology and localized thickening of the peripapillary sclera, in eyes with myopia.
Topics: Female; Humans; Child; Choroid; Fundus Oculi; Optic Disk; Tomography, Optical Coherence; Atrophy; Myopia; Fluorescein Angiography
PubMed: 36007179
DOI: 10.1097/ICB.0000000000001308 -
Survey of Ophthalmology 2022Superior segmental optic nerve hypoplasia (SSONH) is a congenital condition characterized by developmental abnormalities of the superior optic disc and an... (Review)
Review
Superior segmental optic nerve hypoplasia (SSONH) is a congenital condition characterized by developmental abnormalities of the superior optic disc and an underappreciated differential diagnosis for glaucoma. The reported prevalence is less than 1%, although likely underestimated due to the difficulties with diagnosis. The exact pathophysiology of SSONH remains elusive, but a mechanism involving developmental attrition of retinal ganglion cells has been proposed, and maternal diabetes is recognized as a major risk factor. SSONH often is observed incidentally, and the patients typically are then evaluated for an acquired optic atrophy, often glaucoma because of the presence of inferior visual field defects. There are 4 characteristic signs of SSONH: superior entrance of the central retinal artery, superior disc pallor, superior peripapillary halo, and thinning of the superior peripapillary nerve fiber layer; however, the presence of these signs is variable. Optical coherence tomography can be helpful in distinguishing SSONH by demonstrating superonasal retinal nerve fiber layer thinning, as compared to the inferotemporal thinning seen in glaucoma, and an aberrant extension of retinal pigment epithelium over Bruch membrane. Overall, the prognosis of SSONH is favorable, with a non-progressive course. It is essential that ophthalmologists recognize and differentiate SSONH from glaucoma to avoid misdiagnosis and unnecessary treatment.
Topics: Glaucoma; Humans; Optic Disk; Optic Nerve Hypoplasia; Retinal Ganglion Cells; Tomography, Optical Coherence; Visual Field Tests
PubMed: 35189184
DOI: 10.1016/j.survophthal.2022.02.008 -
Bioelectromagnetics Feb 2022Vitreous "floaters" are a common entoptic phenomenon that can result in significant reduction in quality of life in a proportion of sufferers. The authors use a...
Vitreous "floaters" are a common entoptic phenomenon that can result in significant reduction in quality of life in a proportion of sufferers. The authors use a computational mathematical model based on Fourier optics and reflection and transmission coefficients calculated for a planar type II collagen opacity suspended in aqueous to show that floaters are perceived by the patient through interference effects that result in significant variations in intensity on the retina when viewing a constant brightness surface. The model also predicts that backscattered intensity from floaters is ten thousand to one million times lower than the variations in intensity produced on the retina, which demonstrates that the visible effects of floaters for the patient can be highly significant, whereas clinical observation of the vitreous may be entirely unremarkable. Importantly, the results also demonstrate that floaters do not need to be opaque to cause symptoms, with only small differences in refractive index between the floater material and the surrounding vitreous needed to produce significant optical effects. The model predicts that pupil size is an important factor in determining the severity of symptoms from floaters, with constricted pupils giving much greater effect than dilated pupils. Finally, the authors' model predicts that floaters degrade contrast sensitivity function, with greatest degradation occurring in the 5-40 cycles per degree spatial frequency range and that the effects of shadowing caused by floaters are very strongly correlated to the predicted degradation of contrast sensitivity function. Bioelectromagnetics. 43:90-105, 2022. © 2021 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.
Topics: Eye Diseases; Humans; Quality of Life; Retina; Vitreous Body
PubMed: 34969150
DOI: 10.1002/bem.22386 -
Journal of Biomedical Optics Dec 2023The assessment of biomarkers in the eye is rapidly gaining traction for the screening, diagnosis, and monitoring of ocular and neurological diseases. Targeted ocular...
SIGNIFICANCE
The assessment of biomarkers in the eye is rapidly gaining traction for the screening, diagnosis, and monitoring of ocular and neurological diseases. Targeted ocular spectroscopy is a technology that enables concurrent imaging of the eye fundus and analysis of high-quality spectra from a targeted region within the imaged area. This provides structural, compositional, and functional information of specific regions of the eye fundus from a non-invasive approach to ocular biomarker detection.
AIM
The aim of our study was to demonstrate the multimodal functionality and validation of targeted ocular spectroscopy. This was done , using a reference target and a model eye, and .
APPROACH
Images and spectra from different regions of a reference target and a model eye were acquired and analyzed to validate the system. Targeted ocular fluorescence spectroscopy was also demonstrated with the same model. Subsequently, imaging and diffuse reflectance spectra were acquired to assess blood oxygen saturation in the optic nerve head and the parafovea of healthy subjects.
RESULTS
Tests conducted with the reference target showed accurate spectral analysis within specific areas of the imaging space. In the model eye, distinct spectral signatures were observed for the optic disc, blood vessels, the retina, and the macula, consistent with the variations in tissue composition and functions between these regions. An ocular oximetry algorithm was applied to spectra from the optic nerve head and parafovea of healthy patients, showing significant differences in blood oxygen saturation. Finally, targeted fluorescence spectral analysis was performed .
CONCLUSIONS
Diffuse reflectance and fluorescence spectroscopy in specific regions of the eye fundus open the door to a whole new range of monitoring and diagnostic capabilities, from assessment of oxygenation in glaucoma and diabetic retinopathy to photo-oxidation and photodegradation in age-related macular degeneration.
Topics: Humans; Fundus Oculi; Retina; Optic Disk; Oximetry; Spectrometry, Fluorescence
PubMed: 38111476
DOI: 10.1117/1.JBO.28.12.126004 -
Journal of Visualized Experiments : JoVE Apr 2023The ocular micro-dissection of the rodent eye involves the segmentation of the enucleated eyeball with the attached nictitating membrane, or third eyelid, to obtain the...
The ocular micro-dissection of the rodent eye involves the segmentation of the enucleated eyeball with the attached nictitating membrane, or third eyelid, to obtain the anterior and posterior eyecups. With this technique, the sub-parts of the eye, including the corneal tissue, neural tissue, retinal pigment epithelial (RPE) tissue, and lens, can be obtained for wholemounts, cryo-sectioning, and/or single-cell suspensions of a specific ocular tissue. The presence of the third eyelid presents unique and significant advantages, as it benefits the maintenance of the orientation of the eye, which is important for understanding eye physiology following any localized intervention or in studies involving ocular analysis relating to the eye's spatial topography. In this method, we enucleated the eyeball at the socket along with the third eyelid by carefully and slowly cutting through the extraocular muscles and severing the optic nerve. The eyeball was pierced through the corneal limbus using a microblade. The incision was used as the point of entry, allowing for cutting along the corneal-scleral junction by inserting micro-scissors through the incision point. Small and continuous cuts along the circumference were made until the cups separated. These could be further dissected by gently peeling the translucent layer of the neural retina using Colibri suturing forceps to obtain the neural retina and RPE layers. Further, three/four equidistant cuts were made from the periphery perpendicularly to the optic center until the optic nerve was reached. This opened the hemispherical cups into a floret shape so that they fell flat and could be easily mounted. This technique has been used in our lab for corneal wholemounts and retinal sections. The presence of the third eyelid delineates the nasal-temporal orientation, which allows for the study of various cell therapy interventions post-transplantation and, thus, the targeted physiological validation vital for visualization and accurate representation in such studies.
Topics: Animals; Microdissection; Eye; Retina; Retinal Pigment Epithelium; Lens, Crystalline; Cornea
PubMed: 37154568
DOI: 10.3791/64414 -
Acta Ophthalmologica Sep 2022To assess intrapupillary space (IPS) changes in healthy subjects with regard to decreased iris motility in patients with pseudoexfoliation glaucoma (PEXG) or...
PURPOSE
To assess intrapupillary space (IPS) changes in healthy subjects with regard to decreased iris motility in patients with pseudoexfoliation glaucoma (PEXG) or non-arteritic anterior ischaemic optic neuropathy (NAION) in a feasibility study in a clinical environment.
METHODS
Scotopic and photopic IPS measurements using three-dimensionally rendered swept-source optical coherence tomography (SS-OCT) data were obtained and compared for all subjects. Intrapupillary space (IPS) parameters were evaluated such as absolute volumetric differences, relative light response for volumetric ratios and pupillary ejection fraction (PEF) for functional contraction measurements.
RESULTS
From a total of 122 IPS from 66 subjects, 106 IPS were eligible for comparison providing values for 72 normal, 30 PEXG and 4 NAION eyes. In healthy, PEXG and NAION subjects, scotopic overall mean IPS was 8.90, 3.45 and 4.16 mm , and photopic overall mean IPS was 0.87, 0.74 and 1.13 mm , respectively. Three-dimensional contractility showed a mean absolute difference of 8.03 mm for normals (defined as 100% contractility), 2.72 mm for PEXG (33.88% of normal) and 3.03 mm for NAION (38.50% of normal) with a relative light response ratio between scotopic and photopic volumes of 10.26 (100%), 4.69 (45.70%) and 3.67 (35.78%), respectively. Pupillary ejection fraction (PEF) showed a contractile pupillary emptying of 88.11% for normals, 76.92% for PEXG and 70.91% for NAION patients.
CONCLUSION
This 3D pupillometry OCT assessment allows for quantitative measurements of pupil function, contractility and response to light. More specifically, PEF is presented as a potential (neuro)-pupillary outcome measure that could be useful in the monitoring of ophthalmic disorders that affect pupillary function.
Topics: Exfoliation Syndrome; Humans; Iris; Optic Neuropathy, Ischemic; Pupil; Tomography, Optical Coherence
PubMed: 34750988
DOI: 10.1111/aos.15063 -
Applied Optics Apr 2022Nodal points are defined using parallel object and image rays at very small angles to the optical axis, and Johann Listing described them when characterizing the eye in...
Nodal points are defined using parallel object and image rays at very small angles to the optical axis, and Johann Listing described them when characterizing the eye in 1845. They are only distinct from principal points when there is a refractive index difference, but Reginald Clay used the term "nodal slide" in 1904 for equipment that uses lens rotation when measuring a lens focal length in air. Over time, sketches of nodal rays at large angles have become common, and these perhaps appear to support observations that input angles to the eye match image angles measured to the nodal point. Raytrace calculations confirm that this is correct for very large angles, but the relationship comes from the cornea curving around, towards incoming light, angles being rescaled at the exit pupil by a constant factor, and then the retina curving around to meet the image rays. The eye has high linearity, with 1:1 angular scaling occurring at approximately the nodal point, but ray bundles passing through the pupil center, rather than paraxial nodal rays, define the optical properties.
Topics: Cornea; Lens, Crystalline; Pupil; Retina; Vision, Ocular
PubMed: 35471355
DOI: 10.1364/AO.455464 -
Ophthalmology Oct 2021To determine the prevalence of different types of artifacts seen in OCT angiography (OCTA) images of healthy and glaucoma eyes and evaluate the characteristics...
PURPOSE
To determine the prevalence of different types of artifacts seen in OCT angiography (OCTA) images of healthy and glaucoma eyes and evaluate the characteristics associated with poor-quality images.
DESIGN
Retrospective study.
PARTICIPANTS
A total of 649 eyes of 368 healthy, glaucoma suspect, and glaucoma patients.
METHODS
Angiovue (Optovue Inc) high-density (HD) and non-HD optic nerve head and macula OCTA images of participants were evaluated by 4 expert reviewers for the presence of different artifacts, including eye movement, defocus, shadow, decentration, segmentation error, blink, and Z offset in the superficial vascular layer. Each OCTA scan was designated to have good or poor quality based on the presence of artifacts. The association of demographic and ocular characteristics with the likelihood of obtaining poor-quality OCTA images was evaluated.
MAIN OUTCOME MEASURES
The prevalence of OCTA artifacts and the factors associated with increased likelihood of capturing poor-quality OCTA images.
RESULTS
A total of 5263 OCTA images were evaluated. Overall, 33.9% of the OCTA images had poor quality. The majority of images with acceptable quality scores (QS ≥ 4) had no artifacts (76.6%). Other images had 1 (13.6%) or 2 or more artifacts (9.8%). Older age (P < 0.001), male gender (P = 0.045), worse visual field mean deviation (P < 0.001), absence of eye tracking (P < 0.001), and macular scan area (P < 0.001) were associated with a higher likelihood of obtaining poor-quality images. In images with acceptable QS, the commercially available quality measures including QS and signal strength index had the area under the receiver operating characteristic curves of 0.65 (95% confidence interval [CI], 0.62-0.69) and 0.70 (95% CI, 0.68-0.73) to detect good-quality images, respectively.
CONCLUSIONS
OCTA artifacts associated with poor-quality images are frequent, and their prevalence is affected by ocular and patient characteristics. One should not rely solely on the quantitative assessments that are provided automatically by OCTA instruments. A systematic scan review should be conducted to ensure appropriate interpretation of OCTA images. Given the high prevalence of poor-quality OCTA images, the images should be reacquired whenever an apparent and correctable artifact is present on a captured image.
Topics: Aged; Artifacts; Female; Fluorescein Angiography; Fundus Oculi; Humans; Male; Optic Disk; Retinal Ganglion Cells; Retrospective Studies; Tomography, Optical Coherence; Visual Fields
PubMed: 33819524
DOI: 10.1016/j.ophtha.2021.03.036