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Annual Review of Biomedical Engineering Jul 2021As the human eye ages, the crystalline lens stiffens (presbyopia) and opacifies (cataract), requiring its replacement with an artificial lens [intraocular lens (IOL)]....
As the human eye ages, the crystalline lens stiffens (presbyopia) and opacifies (cataract), requiring its replacement with an artificial lens [intraocular lens (IOL)]. Cataract surgery is the most frequently performed surgical procedure in the world. The increase in IOL designs has not been paralleled in practice by a sophistication in IOL selection methods, which rely on limited anatomical measurements of the eye and the surgeon's interpretation of the patient's needs and expectations. We propose that the future of IOL selection will be guided by 3D quantitative imaging of the crystalline lens to map lens opacities, anticipate IOL position, and develop fully customized eye models for ray-tracing-based IOL selection. Conversely, visual simulators (in which IOL designs are programmed in active elements) allow patients to experience prospective vision before surgery and to make more informed decisions about which IOL to choose. Quantitative imaging and optical and visual simulations of postsurgery outcomes will allow optimal treatments to be selected for a patient undergoing modern cataract surgery.
Topics: Cataract; Humans; Lens Implantation, Intraocular; Lens, Crystalline; Ophthalmology; Prospective Studies
PubMed: 33848431
DOI: 10.1146/annurev-bioeng-082420-035827 -
Acta Ophthalmologica Sep 2017To assess thickness and associations of the peripapillary choroidal layers.
PURPOSE
To assess thickness and associations of the peripapillary choroidal layers.
METHODS
The population-based Beijing Eye Study included 3468 participants with an age of 50+ years. Using spectral-domain optical coherence tomography, we measured the large vessel layer (LVL) and small-to-medium vessel layer (SMVL) of the peripapillary choroid in a circular scan with a diameter of 3.4 mm around the optic nerve head centre at eight locations equidistant (45°) to each other. The ratio of SMVL thickness to LVL thickness was calculated.
RESULTS
Measurements were available for 3000 (86.5%) study participants (mean age: 64.4 ± 9.6 years; range: 50-93 years). SMVL (mean thickness: 31 ± 7 μm; range: 17-70 μm) and LVL (103 ± 48 μm; range: 9-313 μm) were thickest superiorly, followed by the temporal region, nasal region, and inferior region. Thicker SMVL was associated (regression coefficient r: 0.33) with younger age (p < 0.001; standardized regression coefficient β: -0.26), higher cognitive function (p = 0.02; β: 0.05), shorter axial length (p < 0.001; β: -0.12), thicker lens (p < 0.001; β: 0.07), smaller disc area (p < 0.001; β: -0.08), smaller parapapillary β/γ zone (p < 0.001; β: -0.10) and lower prevalence of angle-closure glaucoma (p = 0.04; β: -0.04). Thicker LVL thickness was correlated (r: 0.45) with younger age (p < 0.001; β: -0.34) and higher cognitive function (p = 0.01; β: 0.05), shorter axial length (p < 0.001; β: -0.09)), thicker lens (p = 0.009; β: 0.06), smaller disc area (p < 0.001; β: -0.09), smaller parapapillary alpha zone (p = 0.04; β: -0.04), smaller β/γ zone (p < 0.001; β: -0.14) and lower prevalence of angle-closure glaucoma (p = 0.057; β: -0.04). A higher SMVL-to-LVL thickness ratio was related with older age (p < 0.001; β: 0.36), longer axial length (p < 0.001; β: 0.09), lower best-corrected visual acuity (BCVA) (p = 0.002; β: 0.07), larger optic disc area (p < 0.001; β: 0.10) and larger β/γ zone (p < 0.001; β: 0.19).
CONCLUSION
Small-to-medium vessel layer (SMVL) and LVL, thickest superiorly and thinnest inferiorly, increased with younger age and higher cognitive function after adjusting for axial length and prevalence of angle-closure glaucoma. With older age, longer axial length, larger optic disc area and larger β zone, LVL decreased more than SMVL in thickness. The association between thicker peripapillary choroidal thickness and better cognitive function may deserve further attention.
Topics: Aged; Aged, 80 and over; Axial Length, Eye; Beijing; Choroid; Cross-Sectional Studies; Female; Glaucoma, Angle-Closure; Humans; Male; Middle Aged; Optic Disk; Prevalence; Retinal Vessels; Retrospective Studies; Rural Population; Tomography, Optical Coherence; Urban Population; Visual Acuity
PubMed: 28251820
DOI: 10.1111/aos.13379 -
ELife Apr 2023The retina, behind the transparent optics of the eye, is the only neural tissue whose physiology and pathology can be non-invasively probed by optical microscopy. The...
The retina, behind the transparent optics of the eye, is the only neural tissue whose physiology and pathology can be non-invasively probed by optical microscopy. The aberrations intrinsic to the mouse eye, however, prevent high-resolution investigation of retinal structure and function in vivo. Optimizing the design of a two-photon fluorescence microscope (2PFM) and sample preparation procedure, we found that adaptive optics (AO), by measuring and correcting ocular aberrations, is essential for resolving putative synaptic structures and achieving three-dimensional cellular resolution in the mouse retina in vivo. Applying AO-2PFM to longitudinal retinal imaging in transgenic models of retinal pathology, we characterized microvascular lesions with sub-capillary details in a proliferative vascular retinopathy model, and found Lidocaine to effectively suppress retinal ganglion cell hyperactivity in a retinal degeneration model. Tracking structural and functional changes at high-resolution longitudinally, AO-2PFM enables microscopic investigations of retinal pathology and pharmacology for disease diagnosis and treatment in vivo.
Topics: Mice; Animals; Retina; Retinal Ganglion Cells; Retinal Degeneration; Microscopy, Fluorescence; Optics and Photonics
PubMed: 37039777
DOI: 10.7554/eLife.84853 -
Indian Journal of Ophthalmology Nov 2021Diabetic retinopathy (DR) is a leading cause of blindness among adults and the numbers are projected to rise. There have been dramatic advances in the field of retinal... (Review)
Review
Diabetic retinopathy (DR) is a leading cause of blindness among adults and the numbers are projected to rise. There have been dramatic advances in the field of retinal imaging since the first fundus image was captured by Jackman and Webster in 1886. The currently available imaging modalities in the management of DR include fundus photography, fluorescein angiography, autofluorescence imaging, optical coherence tomography, optical coherence tomography angiography, and near-infrared reflectance imaging. These images are obtained using traditional fundus cameras, widefield fundus cameras, handheld fundus cameras, or smartphone-based fundus cameras. Fluorescence lifetime ophthalmoscopy, adaptive optics, multispectral and hyperspectral imaging, and multicolor imaging are the evolving technologies which are being researched for their potential applications in DR. Telemedicine has gained popularity in recent years as remote screening of DR has been made possible. Retinal imaging technologies integrated with artificial intelligence/deep-learning algorithms will likely be the way forward in the screening and grading of DR. We provide an overview of the current and upcoming imaging modalities which are relevant to the management of DR.
Topics: Adult; Artificial Intelligence; Diabetes Mellitus; Diabetic Retinopathy; Fluorescein Angiography; Fundus Oculi; Humans; Photography; Retina; Tomography, Optical Coherence
PubMed: 34708731
DOI: 10.4103/ijo.IJO_1212_21 -
Veterinary Ophthalmology May 2022The purpose was to describe the in vivo microanatomy of typical and atypical chorioretinal and juxtapapillary colobomas in the dog.
PURPOSE
The purpose was to describe the in vivo microanatomy of typical and atypical chorioretinal and juxtapapillary colobomas in the dog.
METHODS
Three cross-breed dogs were found to be affected with colobomas. Two of the cases were NEHJ1 homozygous and Collie Eye Anomaly (CEA) affected and had the typical optic nerve head colobomas seen with the disease. The third case had an unexpected atypical coloboma. In vivo retinal photography and non-invasive retinal imaging by confocal scanning laser ophthalmoscope (cSLO) and optical coherence tomography (OCT) were done, and the eye affected with the atypical coloboma was collected and processed for histopathological evaluation.
RESULTS
The majority of the defining features within the CEA defects were similar, with the extent of change to the choroid being of note. Similar to the first two cases, the atypical coloboma demonstrated absent normal retina, RPE, and choroid within the coloboma. Prominent intercalary membranes and vitreal strands attached to the depth of the coloboma were also apparent in all affected eyes. However, unlike the CEA-associated colobomas, the atypical coloboma possessed normal choroid surrounding the lesion and the depth of the lesion was apparent throughout.
CONCLUSIONS
Advanced retinal imaging enables the appreciation of microanatomical changes that occur in the living eye. The ability of OCT to enhance visualization of abnormal retinal structures and detect subtle neurosensory retinal defects has allowed for the in vivo characterization of features observed in typical and atypical colobomas, as well as the appreciation of some of the resulting structural changes not visible by ophthalmoscopy alone.
Topics: Animals; Choroid; Coloboma; Dog Diseases; Dogs; Retina; Retinal Diseases; Tomography, Optical Coherence
PubMed: 35092136
DOI: 10.1111/vop.12970 -
Graefe's Archive For Clinical and... Jun 2023To compare macular damage in glaucomatous optic neuropathy (GON) and compressive optic neuropathy (CON) and assess its diagnostic accuracy in distinguishing between... (Observational Study)
Observational Study
PURPOSE
To compare macular damage in glaucomatous optic neuropathy (GON) and compressive optic neuropathy (CON) and assess its diagnostic accuracy in distinguishing between diseases.
METHODS
Observational, cross-sectional, single-center study. Patients with GON, CON, and healthy controls were included according to the eligibility criteria. An automated spectral-domain optical coherence tomography (SD-OCT) algorithm was used to segment the circumpapilary retinal nerve fiber layer (cpRNFL) and macula. The layer thickness was measured in each sector according to the Early Treatment Diabetic Retinopathy Study and the 6-sector Garway-Heath-based grids. Data was compared across all study groups, and the significance level was set at 0.05.
RESULTS
Seventy-five eyes of 75 participants, 25 with GON, 25 with CON, and 25 healthy controls (CG), were included. Macular thickness was diminished in the ganglion cell complex of GON and CON patients compared to CG (p<0.05). The best Garway-Heath-based grid parameters for distinguishing GON and CON were the nasal-inferior (NI) and nasal-superior sectors and the NI/temporal inferior (TI) damage ratios in the macular ganglion cell (mGCL) and inner plexiform (IPL) layers. Moreover, the combination of the NI sector and NI/TI damage ratios in both layers had higher discriminative power (AUC 0.909; 95% CI 0.830-0.988; p<0.001) than combining parameters in each layer separately.
CONCLUSION
Our findings suggest that the evaluation of macular segmented layers damage by SD-OCT may be a helpful add-on tool in the differential diagnosis between GON and CON.
Topics: Humans; Optic Disk; Cross-Sectional Studies; Retinal Ganglion Cells; Nerve Fibers; Optic Nerve Diseases; Glaucoma; Macula Lutea; Tomography, Optical Coherence
PubMed: 36625929
DOI: 10.1007/s00417-022-05962-6 -
Investigative Ophthalmology & Visual... Aug 2019To define the shape of the anterior surface of the peripapillary sclera (PPS) and evaluate its relationship with age and ocular determinants in a population-based...
PURPOSE
To define the shape of the anterior surface of the peripapillary sclera (PPS) and evaluate its relationship with age and ocular determinants in a population-based Chinese cohort.
METHODS
The optic nerve heads of 619 healthy Chinese subjects were imaged with spectral-domain optical coherence tomography. To assess the shape of the PPS/Bruch's membrane (BM), we measured the angle between a line parallel to the nasal anterior PPS/BM boundary and one parallel to the temporal side. A negative value indicated that the PPS/BM followed an inverted v-shaped configuration (peak pointing toward the vitreous), whereas a positive value indicated that it followed a v-shaped configuration (peak pointing toward the orbital tissues). A linear regression model was used to evaluate the relationship between the PPS angle and other ocular parameters.
RESULTS
The mean PPS angle was 3.68° ± 6.73° and the BM angle was 9.69° ± 5.05°. The PPS angle increased on average by 0.233 deg/y. A v-shaped PPS was significantly associated with age (β = 0.087, P = 0.004), peripapillary choroidal thickness (β = -0.479, P < 0.001), lamina cribrosa depth (β = 0.307, P < 0.001), and BM angle (β = 0.487, P < 0.001) after adjusting for best corrected visual acuity, central corneal thickness, and axial length.
CONCLUSIONS
The anterior surface of PPS of an elderly adult population had a v-shaped configuration and was more pronounced with increasing age, thin peripapillary choroid, and a deep cup. Such a change in shape with age could have an impact on the biomechanical environment of the optic nerve head.
Topics: Adult; Aged; Aged, 80 and over; Aging; Asian People; Bruch Membrane; Female; Humans; Male; Middle Aged; Optic Disk; Sclera; Singapore; Tomography, Optical Coherence
PubMed: 31369672
DOI: 10.1167/iovs.19-26777 -
Experimental Eye Research Sep 2023The purpose was to quantify ocular dopamine in rabbits after stimulation of the optic nerve head with short-wavelength (blue) light to activate melanopsin expressed in...
The purpose was to quantify ocular dopamine in rabbits after stimulation of the optic nerve head with short-wavelength (blue) light to activate melanopsin expressed in the axons of intrinsically photosensitive retinal ganglion cells (ipRGCs). Dopamine levels in tears, aqueous humor, vitreous body, and retina (including choroid) were quantified after blue light stimulation of the optic nerve head of 15 rabbits with an optical fiber for 1 min, 10 min, or no stimulation (n = 5, each group). The left eye of all rabbits was operated on to introduce the optical fiber and stimulate the optic nerve, while the contralateral eye served as internal control. One minute of blue light stimulation significantly increased dopamine concentration in the vitreous body of the treated eyes compared to the contralateral ones (P = 0.015). Stimulation for 10 min significantly increased dopamine concentration in the vitreous body, as well as the aqueous humor (P < 0.05). Therefore, using an optical fiber approach to stimulate the optic nerve head with blue light significantly increased dopamine concentration in the aqueous humor and the vitreous body. This likely reflects an upregulation of retinal dopamine synthesis that could be attributed to ipRGC activation. However, the data provided in this study fell short of establishing a definitive link between dopamine release and ipRGC activation, mainly due to the lack of evidence supporting the expression of the melanopsin photopigment in the optic nerve.
Topics: Animals; Rabbits; Optic Disk; Dopamine; Retina; Retinal Ganglion Cells; Light; Rod Opsins; Photic Stimulation
PubMed: 37499737
DOI: 10.1016/j.exer.2023.109604 -
Scientific Reports Mar 2022Miniature varifocal lenses are crucial for many applications requiring compact optical systems. Here, utilizing electro-mechanically actuated 0.5-mm aperture infrared...
Miniature varifocal lenses are crucial for many applications requiring compact optical systems. Here, utilizing electro-mechanically actuated 0.5-mm aperture infrared Alvarez meta-optics, we demonstrate 3.1 mm (200 diopters) focal length tuning with an actuation voltage below 40 V. This constitutes the largest focal length tuning in any low-power electro-mechanically actuated meta-optic, enabled by the high energy density in comb-drive actuators producing large displacements at relatively low voltage. The demonstrated device is produced by a novel nanofabrication process that accommodates meta-optics with a larger aperture and has improved alignment between meta-optics via flip-chip bonding. The whole fabrication process is CMOS compatible and amenable to high-throughput manufacturing.
Topics: Equipment Design; Lens, Crystalline; Lenses; Micro-Electrical-Mechanical Systems; Optics and Photonics
PubMed: 35354839
DOI: 10.1038/s41598-022-09277-8 -
Neurobiology of Aging Nov 2018Aging is a major risk factor for age-related ocular diseases including age-related macular degeneration in the retina and retinal pigment epithelium (RPE), cataracts in...
Aging is a major risk factor for age-related ocular diseases including age-related macular degeneration in the retina and retinal pigment epithelium (RPE), cataracts in the lens, glaucoma in the optic nerve, and dry eye syndrome in the cornea. We used targeted metabolomics to analyze metabolites from young (6 weeks) and old (73 weeks) eyes in C57 BL6/J mice. Old mice had diminished electroretinogram responses and decreased number of photoreceptors in their retinas. Among the 297 detected metabolites, 45-114 metabolites are significantly altered in aged eye tissues, mostly in the neuronal tissues (retina and optic nerve) and less in cornea, RPE/choroid, and lens. We noted that changes of metabolites in mitochondrial metabolism and glucose metabolism are common features in the aged retina, RPE/choroid, and optic nerve. The aging retina, cornea, and optic nerve also share similar changes in Nicotinamide adenine dinucleotide (NAD), 1-methylnicotinamides, 3-methylhistidine, and other methylated metabolites. Metabolites in taurine metabolism are strikingly influenced by aging in the cornea and lens. In conclusion, the aging eye has both common and tissue-specific metabolic signatures. These changes may be attributed to dysregulated mitochondrial metabolism, reprogrammed glucose metabolism and impaired methylation in the aging eye. Our findings provide biochemical insights into the mechanisms of age-related ocular changes.
Topics: Aging; Animals; Choroid; Cornea; Electroretinography; Eye; Female; Male; Metabolomics; Mice, Inbred C57BL; Mitochondria; Optic Nerve; Photoreceptor Cells; Retina; Retinal Pigment Epithelium
PubMed: 30172221
DOI: 10.1016/j.neurobiolaging.2018.07.024