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Preconditioning with carbon monoxide inhalation promotes retinal ganglion cell survival against optic nerve crush via inhibition of the apoptotic pathway
摘要： Optic neurodegeneration, in addition to central nervous trauma, initiates impairments to neurons resulting in retinal ganglion cell (RGC) damage. Carbon monoxide (CO) has been observed to elicit neuroprotection in various experimental models. The present study investigated the potential retinal neuroprotection of preconditioning with CO inhalation in a rat model of optic nerve crush (ONC). Adult male Sprague-Dawley rats were preconditioned with inhaled CO (250 ppm) or air for 1 h prior to ONC. Animals were euthanized at 1 or 2 weeks following surgery. RGC densities were quantified by hematoxylin and eosin (H&E) staining and FluoroGold labeling. Visual function was measured via flash visual evoked potentials (FVEP). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and caspase-9 and caspase-3 activity in the retinas, were assessed at 2 weeks post-ONC. The RGC density of CO + crush rats was significantly increased compared with that of the corresponding crush-only rats at 2 weeks (survival rate, 66.2 vs. 48.2% as demonstrated by H&E staining, P<0.01; and 67.6 vs. 37.6% as demonstrated by FluoroGold labeling, P<0.05). FVEP measures indicated a significantly better-preserved latency and amplitude of the P1 wave in the CO + crush rats compared with the crush-only rats. The TUNEL assays demonstrated fewer apoptotic cells in the CO + crush group compared with the crush-only group, accompanied by the suppression of caspase-9 and caspase-3 activity. The results of the present study suggested that inhaled CO preconditioning may be neuroprotective against ONC insult via inhibition of neuronal apoptosis.
关键词： neuroprotection,optic nerve crush,carbon monoxide,preconditioning,retinal ganglion cell
更新于2025-09-23 15:22:29
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Autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytoma
摘要： The authors report fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (OCT ) findings of two consecutive patients who presented with optic disk melanocytoma (ODM). A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up.
关键词： Melanoma/diagnosis,Female,Adult,Male,Case reports,Optic nerve neoplasms/diagnosis,Fluorescein angiography,Humans,Tomography, optical coherence
更新于2025-09-23 15:22:29
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High-Resolution Direct Ophthalmoscopy With an Unmodified iPhone X
摘要： There has been a steady decline in the amount of time dedicated to ophthalmology training in medical school, which leaves many physicians unable to perform adequate direct ophthalmoscopy. However, this is a useful clinical skill that allows the clinician to assess the red reflex, retina, and optic nerve. Visualization of the optic nerve is of particular interest to physicians of many specialties, and a host of abnormalities (including neovascularization, swelling, hemorrhages, and atrophy) can be seen there. To counter deteriorating ophthalmoscopy skills, dedicated devices have been produced that allow ophthalmoscopic examination in the clinic, ward, community, and emergency department. These perform well, but they are not available in all clinical care settings. However, smartphones seem to be ubiquitous in these settings. Direct smartphone ophthalmoscopy can be performed with the addition of a device using prisms or mirrors. Indirect smartphone ophthalmoscopy usually requires a condensing lens, which may not be available to nonophthalmologists in all clinical care settings. We report a technique that allows direct smartphone ophthalmoscopy using only an unmodified iPhone X (priced at $999) without any additional device or software.
关键词： iPhone X,optic nerve,direct ophthalmoscopy,ophthalmoscopy,smartphone
更新于2025-09-23 15:21:01
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Enhanced Structure-Function Relationship in Glaucoma With an Anatomically and Geometrically Accurate Neuroretinal Rim Measurement
摘要： PURPOSE. To evaluate the structure–function relationship between disc margin–based rim area (DM-RA) obtained with confocal scanning laser tomography (CSLT), Bruch’s membrane opening–based horizontal rim width (BMO-HRW), minimum rim width (BMO-MRW), peripapillary retinal nerve fiber layer thickness (RNFLT) obtained with spectral-domain optical coherence tomography (SD-OCT), and visual field sensitivity. METHODS. We examined 151 glaucoma patients with CSLT, SD-OCT, and standard automated perimetry on the same day. Optic nerve head (ONH) and RNFL with SD-OCT were acquired relative to a fixed coordinate system (acquired image frame [AIF]) and to the eye-specific fovea-BMO center (FoBMO) axis. Visual field locations were mapped to ONH and RNFL sectors with fixed Garway-Heath (VFGH) and patient-specific (VFPS) maps customized for various biometric parameters. RESULTS. Globally and sectorally, the structure–function relationships between DM-RA and VFGH, BMO-HRWAIF and VFGH, and BMO-HRWFoBMO and VFPS were equally weak. The R2 for the relationship between DM-RA and VFGH ranged from 0.1% (inferonasal) to 11% (superotemporal) whereas that between BMO-HRWAIF and VFGH ranged from 0.1% (nasal) to 10% (superotemporal). Relatively stronger global and sectoral structure–function relationships with BMO-MRWAIF and with BMO-MRWFoBMO were obtained. The R2 between BMO-MRWAIF and VFGH ranged from 5% (nasal) to 30% (superotemporal), whereas that between BMO-MRWFoBMO and VFPS ranged from 5% (nasal) to 25% (inferotemporal). The structure–function relationship with RNFLT was not significantly different from that with BMO-MRW, regardless of image acquisition method. CONCLUSIONS. The structure–function relationship was enhanced with BMO-MRW compared with the other neuroretinal rim measurements, due mainly to its geometrically accurate properties.
关键词： glaucoma,structure–function relationship,visual field,optic nerve head,automated perimetry
更新于2025-09-23 15:21:01
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Microvascular changes in macula and optic nerve head after femtosecond laser-assisted LASIK: an optical coherence tomography angiography study
摘要： To measure the microcirculation change of macula and optic nerve head before and after femtosecond laser assisted laser in situ keratomileusis. In total 45 eyes from 45 subjects, who underwent FS-LASIK during June 2017 to December 2017 in Guangdong Provincial People’s Hospital, were recruited in this study. Vessel density in macula and optic nerve head were measured by optical coherence tomography angiography before and after transient elevation in intraocular pressure caused by application of suction ring during surgery. Vessel density (VD) at superficial (SCP) plexus of macular region did not differ after surgery (F(3,132) = 1.41, P = 0.24), while the deep (DCP) plexus of macular region significantly decreased 1 day after surgery (P = 0.001) but returned to its baseline value 1 month postoperatively (P = 0.1). Vessel density of optic nerve head region had no significant changes after surgery (F(2.51,95.18) = 0.6, P = 0.59). A short-term temporary decrease of vessel density at deep layer of macular region was observed in eyes undergoing FS-LASIK. However, the retinal capillary density went back to preoperative level 1 month after surgery. Therefore, transient IOP spike during FS-LASIK did not cause long-term decline of retinal microcirculation.
关键词： Optical coherence tomography angiography,Femtosecond laser-assisted LASIK,Microvascular changes,Macula,Optic nerve head
更新于2025-09-23 15:19:57
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Optic Nerve Head Volumetry by Optical Coherence Tomography in Papilledema Related to Idiopathic Intracranial Hypertension
摘要： Purpose: Idiopathic intracranial hypertension (IIH) leads to optic nerve head swelling and optic atrophy if left untreated. We wanted to assess an easy to perform volumetric algorithm to detect and quantify papilledema in comparison to retinal nerve fiber layer (RNFL) analysis using optical coherence tomography (OCT). Methods: Participants with and without IIH underwent visual acuity testing at different contrast levels and static perimetry. Spectralis-OCT measurements comprised standard imaging of the peripapillary RNFL and macular ganglion cell layer (GCL). The optic nerve head volume (ONHV) was determined using the standard segmentation software and the 3.45 mm early treatment diabetic retinopathy study (ETDRS) grid, necessitating manual correction within Bruch membrane opening. Three neuro-ophthalmologists graded fundus images according to the Frisén scale. A mixed linear model (MLM) was used to determine differences between study groups. Sensitivity and specificity was evaluated using the area under the receiver-operating characteristic (ROC). Results: Twenty-one patients with IIH had an increased ONHV of 6.46 ± 2.36 mm3 as compared to 25 controls with 3.20 ± 0.25 mm3 (P < 0.001). The ONHV cutoff distinguishing IIH from controls was 3.97 mm3 (i.e. no patient with IIH had an ONHV below and no healthy individual above this value). The area under the curve (AUC) for ONHV was 0.99 and for the RNFL at 3.5 mm 0.90. The Frisén scale grading correlated higher with the ONHV (r = 0.90) than with the RNFL thickness (r = 0.68). ONHV measurements were highly reproducible in both groups (coefficient of variation <0.01%). Conclusions: OCT-based volumetry of the optic nerve head discriminates very accurately between individuals with and without IIH. It may serve as a useful adjunct to the rating with the subjective and ordinal Frisén scale. Translational Relevance: A simple OCT protocol run on the proprietary software of a commercial OCT device can reliably discriminate between normal optic nerve heads or pseudo-papilledema and true papilledema while being highly reproducible. Our normative data and OCT preset may be used in further clinical studies.
关键词： optical coherence tomography,pseudotumor cerebri syndrome,idiopathic intracranial hypertension,papilledema,optic nerve head volume
更新于2025-09-23 15:19:57
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Future clinical applicability of optical coherence tomography angiography
摘要： Optical coherence tomography angiography (OCT-A) is an emerging technology that allows for the non-invasive imaging of the ocular microvasculature. Despite the wealth of observations and numerous research studies illustrating the potential clinical uses of OCT-A, this technique is currently rarely used in routine clinical settings. In this review, technical and clinical aspects of OCT-A imaging are discussed, and the future clinical potential of OCT-A is considered. An understanding of the basic principles and limitations of OCT-A technology will better inform clinicians of its future potential in the diagnosis and management of ocular diseases.
关键词： ocular microvasculature,corneal vascularisation image artifact,segmentation,optical coherence tomography angiography,optic nerve head disease,algorithm,retinal disease
更新于2025-09-23 15:19:57
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Retinal nerve fibre layer thickness in a healthy Nepalese population by spectral domain optical coherence tomography
摘要： Objective: To determine the normal values for peripapillary retinal nerve fibre layer thickness (RNFL) measured by spectral domain optical coherence tomography (SD-OCT) in a healthy Nepalese population and to compare the RNFL thicknesses between the genders and among the various age groups. Material and methods: One hundred and fifty six eyes of 156 healthy Nepalese subjects (66 males and 88 females) of various age groups were enrolled in this observational, cross-sectional, hospital-based study. The peripapillary RNFL of the randomly chosen eye of each subject was imaged with a high resolution SD-OCT (Spectralis HRA+OCT, Heidelberg Engineering). The RNFL thickness was measured around the optic nerve head using 16 automatically averaged, consecutive, circular B scans with a 3.4 mm diameter and compared between the genders and among the various age groups. Results: The mean age of the subjects was 38.94 ± 17.00 years (range - 14 to 76 years). The average peripapillary RNFL was found to be 102.64 ± 9.56 μm (95 % CI 97.01 - 101.93). The mean ± SD peripapillary RNFL measurements at the superior, nasal, inferior and temporal sectors in the study population were 129.51 ± 15.09 μm, 76.55 ± 12.02 μm, 134.53 ± 17.19 μm and 70.74 ± 15.53 μm respectively. The average RNFL thickness was 99.47 ± 10.18 μm in the male whereas it was 105.09 ± 8.31 μm in the female participants. The RNFL decreased by 2.26 μm per age perdecade. Conclusion: The Average RNFL thickness is 102.64 ± 9.56 μm in the Nepalese population. Gender and age related variation in the RNFL can serve as a useful guideline in the diagnosis of glaucoma in our population.
关键词： optic nerve head,retinal nerve fibre layer,optical coherence tomography
更新于2025-09-19 17:15:36
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Response of the Retinal Nerve Fiber Layer Reflectance and Thickness to Optic Nerve Crush
摘要： PURPOSE. To study the effects of acute optic nerve damage on the re?ectance of the retinal nerve ?ber layer (RNFL) and to compare the time courses of changes of RNFL re?ectance and thickness. METHODS. A rat model of optic nerve crush (ONC) was compared with previously studied normal retinas. The re?ectance and thickness of the RNFL were studied at 1 to 5 weeks after ONC. Re?ectance spectra from 400 to 830 nm were measured for eyes with ONC, their contralateral untreated eyes, and eyes with sham surgery. Directional re?ectance was studied by varying the angle of incidence. RNFL thickness was measured by confocal microscopy. RESULTS. After ONC, the RNFL re?ectance remained directional. At 1 week, RNFL re?ectance decreased signi?cantly at all wavelengths (P < 0.001), whereas there was no signi?cant change in RNFL thickness (P ? 0.739). At 2 weeks, both RNFL re?ectance and thickness decreased signi?cantly, and by 5 weeks they declined to approximately 40% and 30%, respectively, of the normal values. Although RNFL re?ectance decreased at all wavelengths, there was a greater reduction at short wavelengths. Spectral shape at long wavelengths was similar to the normal. Some of these changes were also found in the contralateral untreated eyes, but none of these changes were found in eyes with sham surgery. CONCLUSIONS. Decrease of RNFL re?ectance after ONC occurs prior to thinning of the RNFL and the decrease is more prominent at short wavelengths. Direct measurement of RNFL re?ectance, especially at short wavelengths, may provide early detection of axonal damage.
关键词： optic nerve crush,optical properties,thinning of the RNFL,directional reflectance,retinal nerve fiber layer
更新于2025-09-19 17:15:36
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Do microvascular changes occur preceding neural impairment in early-stage diabetic retinopathy? Evidence based on the optic nerve head using optical coherence tomography angiography
摘要： Aims To evaluate the microvascular and neural differences of the optic nerve head (ONH) between type 2 diabetes mellitus (T2DM) subjects and controls. Methods This was a cross-sectional observational study. One hundred and eight eyes of 108 T2DM subjects with or without diabetic retinopathy (DR) (54 preclinical DR and 54 mild-to-moderate DR) were included. Fifty-two eyes of 52 healthy subjects were included as controls. The 4.5-mm Angio Disc scan mode and the ganglion cell complex scan mode were performed with all participants using AngioVue software 2.0 of the optical coherence tomography angiography (OCTA) device. Results Regarding ONH radial peripapillary capillary (RPC) density, the peripapillary region was mainly significantly reduced in the No-DR (NDR) group. Moreover, the RPC density of the peripapillary region and the inside optic disc area were significantly reduced in the non-proliferative DR (NPDR) group. When compared to the controls, significantly reduced peripapillary capillary density in six sections was observed in the NPDR group. However, reduced density was observed in only two sections in the NDR group. The NPDR group had significantly increased focal loss volume (FLV) and reduced peripapillary RNFL thickness in the inferior nasal section compared to those in the controls, but similar changes were not observed in the NDR group. A regression model identified RPCs inside the optic disc as a significant parameter in early-stage DR detection. In the NPDR group, BCVA showed a significantly negative correlation with RPCs inside the optic disc and a significantly positive correlation with FLV. Conclusions OCTA findings of the ONH area may provide evidence that microvascular changes occur preceding neural impairment in early-stage DR. However, further researches are still needed to support the statement. Reduced ONH perfusion inside the optic disc may be one of the crucial biomarkers in early-stage DR detection and is a possible sensitive visual acuity predictor in early-stage DR subjects. With the ONH mode, OCTA may be a more promising tool in DR screening.
关键词： Neural impairment,Optical coherence tomography angiography,Optic nerve head,Microvascular changes,Diabetic retinopathy
更新于2025-09-19 17:15:36