[The effect of keratoconus-associated refractive errors on the results of tomographic methods of studying the posterior structures of the eye]. / Vliyanie opticheskikh narushenii pri keratokonuse na rezul'taty tomograficheskikh metodov issledovaniya struktur zadnego segmenta glaza.

PURPOSE: The study assesses the potential influence of refractive errors in keratoconus (KC) on the results of tomographic methods of studying the structures of the posterior eye segment. MATERIAL AND METHODS: The study included 30 patients with bilateral stabilized KC of stages I-IV in classification by M. Amsler. Spherical and cylindrical components of refractions were determined using automatic refractometry, keratometry measurements - based on scanning keratotopography with Scheimpflug analyzer. Aberrometry was performed to evaluate corneal wave front according to the following parameters: root mean square for lower order aberrations (RMS LOA), root mean square for higher order aberrations (RMS HOA), vertical trefoil, vertical coma, horizontal coma and spherical aberrations. Optical coherence tomography (OCT) and laser confocal scanning ophthalmoscopy (HRT 3) data was used in morphometric analysis of the optic nerve head and peripapillary retina. The following morphometric parameters were analyzed: optic nerve head (ONH) area, optic disc cup area, optic disc cup volume, ratio of optic disc cup area to ONH area, neuroretinal rim area, neuroretinal rim volume, peripapillary retinal nerve fiber layer (RNFL) thickness. All studies were performed first without correction, and 30 minutes after installing customized scleral hard contact lenses (SHCL). RESULTS: Compensation of the refractive errors characteristic for KC was achieved as expected with contact correction. OCT revealed a general trend for reduction in the area and volume of the optic disc cupping, ratio of area to volume of the optic disc cupping, as well as an increase in other parameters. As such, with correction the values for area and volume of the neuroretinal rim according to OCT were 2.2 and 13%, HRT 3 - 18 and 51.6%; comparable increase in mean RNFL thickness - 2.8 and 28.5%, respectively (p<0.001). According to HRT 3 data, the area and volume of optic disc cupping statistically significantly decreased (by 21 and 28%, respectively), while OCT showed statistically significant decrease only in cupping area (by 5.7%). The ratio of cupping to ONH area decreased by 6.6 and 23% relative to the initial data obtained with OCT and HRT 3, respectively. Significant decrease in ONH area amid SHCL correction was observed only with HRT 3. The revealed changes in morphometric parameters were analyzed using the fundamental principles of physiological optics. Changes in interference pattern and, consequently, morphometric parameters of structures of the eye fundus in KC are of multifactorial nature, and are mostly associated with refractive and wave artefacts occurring when the rays pass through the irregular corneal surface and cannot be optically compensated by the device. The use of SHCL as means for making the optic system relatively regular can significantly decrease the artefacts in morphometric measurements. CONCLUSION: The results obtained in this study demonstrate the practicality of tomographic examination in KC with contact correction. The optimal choice is custom-fit SHCL, which along with proper correction of refractive errors also ensures stable position of the lens on the cornea. In standard examination specialists should take into account the «false¼ decrease in parameters of the peripapillary retinal nerve fiber layer and increase in ONH cupping.

Ocular posterior segment microstructural and microvascular morphological changes in protein supplement-consuming bodybuilders.

BACKGROUND: To determine the effects of protein supplement (whey protein powder (PP)) on retinal, choroidal and optic nerve head (ONH) microstructure and microvascular morphology in healthy bodybuilders. METHODS: This cross-sectional study included 23 male adults (consumers, 23 right eyes) who had been routinely consuming whey PP for bodybuilding purposes for ≥ 3 months, and 21 age- and gender-matched healthy volunteers (non-consumers, 21 right eyes) who also attended the gym but did not consume any nutritional supplements. Participants underwent standard ocular exams, enhanced depth imaging optical coherence tomography (EDI OCT), and optical coherence tomography angiography (OCTA) after ≥ 8 h of rest and fasting. RESULTS: Whey PP was consumed for a median of 9.5 (6-12) months. Whey PP consumers had a median age of 22 (21-22) years, while non-consumers had 21 (20-22) years (p = 0.067). Whey PP consumers had greater microstructural thickness than non-consumers, with subfoveal choroidal thickness (301.40 ± 38.91 versus 278.12 ± 33.58 µm; p = 0.035) being significantly different but not central macular thickness (270.55 ± 24.60 versus 265.85 ± 12.44 µm; p = 0.402). Despite a non-significant difference in superficial and deep capillary plexus vascular densities (VDs), whey PP consumers had relatively lower VDs than non-consumers in all macular regions (p > 0.05). Despite this, whey PP consumers displayed greater ONH VDs, as well as higher global RNFL thickness (116.75 ± 10.41 versus 114.50 ± 11.70 µm) than non-consumers (p > 0.05). CONCLUSION: Protein supplements, particularly whey PPs, appear to be associated with different changes in the retina and choroid, as well as ONH microstructural and microvascular morphology, implying that paying attention to these clinical aspects when performing ocular tests in bodybuilders who consume nutritional supplements could be critical.

Measuring Inflammation in the Vitreous and Retina: A Narrative Review.

Uveitis consists of a group of syndromes characterised by intraocular inflammation, accounting for up to 15% of visual loss in the western world and 10% worldwide. Assessment of intraocular inflammation has been limited to clinician-dependent, subjective grading. Developments in imaging technology, such as optical coherence tomography (OCT), have enabled the development of objective, quantitative measures of inflammatory activity. Important quantitative metrics including central macular thickness and vitreous signal intensity allow longitudinal monitoring of disease activity and can be used in conjunction with other imaging modalities enabling holistic assessment of ocular inflammation. Ongoing work into the validation of instrument-based measures alongside development of core outcome sets is crucial for standardisation of clinical trial endpoints and developing guidance for quantitative multi-modal imaging approaches. This review outlines methods of grading inflammation in the vitreous and retina, with a focus on the use of OCT as an objective measure of disease activity.

Vitamin A deficiency and the retinal "double carrot" sign with optical coherence tomography.

BACKGROUND: Spectral-domain optical coherence tomography (SD-OCT) and full-field electroretinography (ERG) allow retinal assessment with vitamin A deficiency (VAD). Using SD-OCT, this study aimed to characterize and follow a novel retinal abnormality in patients with VAD and intramuscular supplementation. METHODS: Patients with VAD were retrospectively reviewed, including SD-OCT and electroretinography. RESULTS: Three patients had VAD following bariatric or colon surgery and varying supplementation. All had nyctalopia, extinguished scotopic rod-specific function with ERG, and decreased serum vitamin A. None demonstrated surface abnormalities. All received intramuscular vitamin A with subjective resolution of symptoms. On SD-OCT, four of six eyes exhibited homogenous foveal hyperreflectivity anterior to retinal pigment epithelium-Bruch complex, reminiscent of a "double carrot", which improved following supplementation. ERG findings demonstrated improved scotopic rod-specific function in all cases; however, photopic function remained diminished in two cases. CONCLUSIONS: Structural improvement of the proposed "double carrot" sign occurs soon after vitamin A supplementation. While scotopic function improves rapidly following supplementation, cone function recovers more slowly. Therefore, foveal changes such as the "double carrot" sign suggest that structural recovery of cones precedes functional recovery.

A moderate dosage of coffee causes acute retinal capillary perfusion decrease in healthy young individuals.

AIM: Caffeinated beverages are very popular across populations and cultures, but quantitative evidence of the acute effects of moderate coffee doses on retinal perfusion is sparse and contradicting. Thus, the aim of this randomized, cross-over and parallel-group design study was to investigate whether moderate consumption of coffee alters macular retinal capillary perfusion in young healthy individuals. METHODS: Twenty-seven young healthy individuals were recruited for this study. Acute changes in retinal microvasculature were assessed using spectral-domain optical coherence tomography angiography (SD-OCTA) at baseline, 0.5 h, and 2 h after intake of coffee, or water. Meanwhile, cerebral blood flow (CBF) and retina-choroid blood flow were evaluated in a parallel-group design (4 participants each in coffee or water group) using magnetic resonance imaging (MRI) with pseudo-continuous arterial spin labeling sequences. RESULTS: Two hours after coffee intake, blood caffeine concentration increased from 0 to 5.05 ± 1.36 µg/mL. Coffee caused a significant decrease in retinal vessel diameter index (VDI) (19.05 ± 0.24 versus [vs] 19.13 ± 0.26; p < 0.001) and CBF in the frontal lobe (77.47 ± 15.21 mL/100 mL/min vs. 84.13 ± 15.55 mL/100 mL/min; p < 0.05) 2 h after intake. However, it significantly increased retina-choroid blood flow after 0.5 and 2 h (163.18 ± 61.07 mL/100 mL/min vs. 132.68 ± 70.47 mL/100 mL/min, p < 0.001, and 161.21 ± 47.95 vs. 132.68 ± 70.47; p < 0.001, respectively). CONCLUSION: This is the first study to demonstrate the acute effects of daily dose coffee consumption on retinal capillary perfusion using SD-OCTA combinate with blood flow MRI. The findings imply that although moderate coffee intake caused a significant increase in retina-choroid blood flow, there was a significant acute decrease both in macular retinal capillary perfusion and CBF.

The Feasibility of Using Ultra-Widefield Retinal Imaging to Identify Ocular Pathologies amongst Those with Systemic Medical Disease Attending a Tertiary Healthcare Facility at a University Hospital.

AIMS: The aim of the study was to evaluate the feasibility of ultra-widefield (UWF) imaging to identify ocular pathologies amongst in- and out-patients in a tertiary university hospital. METHODS: We followed a prospective double-blinded multicenter clinical study. In total, 634 patients from a university hospital with pulmonary, cardiovascular, and endocrine diseases were examined by two teams by conventional slit-lamp biomicroscopy (CBM). UWF images with Optos Tx200 were taken and subsequently graded independently by two retina specialists and graders from two reading centers for the presence of pre-defined pathologies. Interrater reliability was calculated using Fleiss statistical software. An independent, trained and certified ophthalmologist with retinal subspecialty (BL) classified all UWF images with retinal hemorrhages by severity and interrater agreement. RESULTS: Complete data were available for 502 patients. The Moorfields Eye Hospital Reading Center, London, UK (RM), reported the highest number of cases with retinal pathologies (378), and the Reading Center GRADE Bonn, Germany (RB), did so for cases with optic disc cupping (466). Two retinal consultants (R1 and R2) from the Department of Ophthalmology, University Hospital Giessen and Marburg GmbH, Campus Giessen, Germany, noted optic disc pathologies. R1 reported 151 cases with optic disc pallor, while R2 reported only 39 disc pathologies. Both for clinical and for image readers, the early changes had equally low interrater reliability. The presence of at least 3 retinal hemorrhages had the highest interrater reliability (0.59). CONCLUSIONS: UWF imaging is convenient to identify overt retinal pathologies in patients at risk of ocular complications of their systemic disease who are attending hospital clinics. Imaging the eye allows for remote retinal assessment and for placing the patient into the appropriate clinical pathway for ophthalmology. PRECIS: UWF-imaging in a population of in- and out-patients at a university hospital who are at risk of retinal complications is effective to detect overt retinal pathologies and allows for tele-ophthalmology approaches to be enabled for placing the patients into the appropriate clinical pathways.

The effect of hyperbaric oxygen therapy on retina, choroidal thickness, and choroidal vascularity index.

PURPOSE: To determine the acute and cumulative effect of hyperbaric oxygen therapy (HBOT) on retina and choroid tissue in healthy eyes. MATERIAL AND METHODS: Thirty-five subjects who were planned to undergo HBOT for non-ophthalmologic indications comprised the population of this prospective study. Central macular thickness (CMT), retinal nerve fiber layer (RNFL), and choroidal thickness (CT) (3 points: subfoveal area, 500 µm nasal and fovea temporal) were measured using spectral-domain optical coherence tomography (SD-OCT) before HBOT and half an hour after the 1st and 20th sessions of HBOT. The subfoveal choroidal area was segmented using ImageJ software with the binarization technique on enhanced depth imaging (EDI) OCT images. Choroidal area (CA), luminal area (LA), and stromal area (SA) were calculated. Choroidal vascularity index (CVI) was determined as the ratio between LA and CA. RESULTS: The right eyes of 35 patients aged between 22 and 59 years were enrolled in the study. The mean CMT values of the patients were 259.36 ± 22.31 µm, 256.94 ± 22.72 µm, and 254.58 ± 23.02 µm before HBOT, after the 1st session, and after the 20th session, respectively. The change in CMT values before and after HBOT was statistically significant (p=0.001). When the patients' RNFL, CT, CA, SA, LA, and CVI changes before and after the HBOT were examined, no statistically significant difference was found (p>0.05). CONCLUSIONS: Our study jointly evaluates the effect of HBOT on the vascular and stromal components of the choroid and macula in healthy eyes. Due to its thinning effect on the macula, it can be preferred as an adjunctive and facilitating treatment option in addition to current treatments in patients with macular edema due to retinal vascular disorders.

[Effect of acupuncture on retinal and choroidal thickness in patients with optic atrophy].

OBJECTIVE: To observe the effect of acupuncture on visual acuity, intraocular pressure, visual field, retinal and choroidal thickness on optic disc and macular area in patients with optic atrophy. METHODS: A total of 33 patients with optic atrophy were treated with acupuncture. Acupuncture was given at Chengqi (ST 1), Shangjingming (Extra), Qiuhou (EX-HN 7) and Fengchi (GB 20) etc., 30 min each time, once a day, for 14 days. The visual acuity, intraocular pressure, visual field indexes (mean deviation [MD], pattern standard deviation [PSD] and visual field index [VFI]), optic disc retinal nerve fiber layer thickness, macular retinal thickness and choroidal thickness of optic disc and sub-foveal were compared before and after treatment. RESULTS: Compared before treatment, the visual acuity was increased (P<0.05), the MD value was decreased (P<0.05), the thickness of nerve fiber layer on the upper temporal side of optic disc was thinner (P<0.05), and the choroidal thickness of average, nasal side and lower temporal side of optic disc was increased (P<0.05). There was significant correlation between visual field MD and retinal nerve fiber layer thickness in different quadrants before and after treatment (P<0.01). CONCLUSION: Acupuncture could improve visual acuity, increase choroidal thickness in part of optic disc area in patients with optic atrophy.

TRANSCORNEAL ELECTRICAL STIMULATION THERAPY MAY HAVE A STABILIZATION EFFECT ON MULTIFOCAL ELECTRORETINOGRAPHY FOR PATIENTS WITH RETINITIS PIGMENTOSA.

PURPOSE: To assess the effects of transcorneal electrical stimulation (TES) on several measures of visual function in retinitis pigmentosa. METHODS: This prospective, randomized, fellow-eye-controlled study includes 30 eyes of 15 patients with retinitis pigmentosa. Each patient's eyes were randomly selected as treatment (TE) and control eye (CE), and 30 minutes/week TES was applied for 6 months. Patient evaluations were performed before and after TES, including comprehensive ophthalmological examination, visual fields, full-field and multifocal electroretinography, microperimetry, and optical coherence tomography. All parameters were compared before and after TES and between TE and CE. RESULTS: After TES, the mean signal amplitudes in multifocal electroretinography were stabilized in TE. The mean signal amplitudes in CE decreased in every ring, reaching significance in the fifth ring (847.15 ± 393.94 and 678.77 ± 282.66 nV, P = 0.039, before and after TES, respectively). The changes in the mean signal amplitudes of TE and CE were -0.38 ± 295.53 and -185.15 ± 332,62 nV in second (P = 0.046), 36.69 ± 326.4 and -143.38 ± 317,41 nV in fourth (P = 0.028), and -17.46 ± 333.07 and -168.38 ± 297,14 nV in fifth rings (P = 0.046), respectively. The decrease in the mean signal amplitudes between 2° and 20° midperipheral retina was significantly less in TE (-33.59 ± 225,1 nV) than CE (-205.56 ± 345.1 nV) (P = 0.011). There were no significant changes in other parameters. CONCLUSION: The progression in multifocal electroretinography might be stabilized with TES. Further studies with larger sample sizes and a longer follow-up are needed to conclude that TES reduces retinitis pigmentosa progression.

Effect of acupuncture on retinal and choroidal thickness in patients with optic atrophy / 中国针灸

OBJECTIVE@#To observe the effect of acupuncture on visual acuity, intraocular pressure, visual field, retinal and choroidal thickness on optic disc and macular area in patients with optic atrophy.@*METHODS@#A total of 33 patients with optic atrophy were treated with acupuncture. Acupuncture was given at Chengqi (ST 1), Shangjingming (Extra), Qiuhou (EX-HN 7) and Fengchi (GB 20) etc., 30 min each time, once a day, for 14 days. The visual acuity, intraocular pressure, visual field indexes (mean deviation [MD], pattern standard deviation [PSD] and visual field index [VFI]), optic disc retinal nerve fiber layer thickness, macular retinal thickness and choroidal thickness of optic disc and sub-foveal were compared before and after treatment.@*RESULTS@#Compared before treatment, the visual acuity was increased (P<0.05), the MD value was decreased (P<0.05), the thickness of nerve fiber layer on the upper temporal side of optic disc was thinner (P<0.05), and the choroidal thickness of average, nasal side and lower temporal side of optic disc was increased (P<0.05). There was significant correlation between visual field MD and retinal nerve fiber layer thickness in different quadrants before and after treatment (P<0.01).@*CONCLUSION@#Acupuncture could improve visual acuity, increase choroidal thickness in part of optic disc area in patients with optic atrophy.

Simultaneous directional full-field OCT using path-length and carrier multiplexing.

Full-field swept-source optical coherence tomography (FF-SS-OCT) is an emerging technology with potential applications in ophthalmic imaging, microscopy, metrology, and other domains. Here we demonstrate a novel method of multiplexing FF-SS-OCT signals using carrier modulation (CM). The principle of CM could be used to inspect various properties of the scattered light, e.g. its spectrum, polarization, Doppler shift, or distribution in the pupil. The last of these will be explored in this work, where CM was used to acquire images passing through two different optical pupils. The two pupils contained semicircular optical windows with perpendicular orientations, with each window permitting measurement of scattering anisotropy in one dimension by inducing an optical delay between the images formed by the two halves of the pupil. Together, the two forms of multiplexing permit measurement of differential scattering anisotropy in the x and y dimensions simultaneously. To demonstrate the feasibility of this technique our carrier multiplexed directional FF-OCT (CM-D-FF-OCT) system was used to acquire images of a microlens array, human hair, onion skin and in vivo human retina. The results of these studies are presented and briefly discussed in the context of future development and application of this technique.

HDC-Net: A hierarchical dilation convolutional network for retinal vessel segmentation.

The cardinal symptoms of some ophthalmic diseases observed through exceptional retinal blood vessels, such as retinal vein occlusion, diabetic retinopathy, etc. The advanced deep learning models used to obtain morphological and structural information of blood vessels automatically are conducive to the early treatment and initiative prevention of ophthalmic diseases. In our work, we propose a hierarchical dilation convolutional network (HDC-Net) to extract retinal vessels in a pixel-to-pixel manner. It utilizes the hierarchical dilation convolution (HDC) module to capture the fragile retinal blood vessels usually neglected by other methods. An improved residual dual efficient channel attention (RDECA) module can infer more delicate channel information to reinforce the discriminative capability of the model. The structured Dropblock can help our HDC-Net model to solve the network overfitting effectively. From a holistic perspective, the segmentation results obtained by HDC-Net are superior to other deep learning methods on three acknowledged datasets (DRIVE, CHASE-DB1, STARE), the sensitivity, specificity, accuracy, f1-score and AUC score are {0.8252, 0.9829, 0.9692, 0.8239, 0.9871}, {0.8227, 0.9853, 0.9745, 0.8113, 0.9884}, and {0.8369, 0.9866, 0.9751, 0.8385, 0.9913}, respectively. It surpasses most other advanced retinal vessel segmentation models. Qualitative and quantitative analysis demonstrates that HDC-Net can fulfill the task of retinal vessel segmentation efficiently and accurately.

Roughness of retinal layers in Alzheimer's disease.

There is growing evidence that thinned retinal regions are interspersed with thickened regions in all retinal layers of patients with Alzheimer's disease (AD), causing roughness to appear on layer thickness maps. The hypothesis is that roughness of retinal layers, assessed by the fractal dimension (FD) of their thickness maps, is an early biomarker of AD. Ten retinal layers have been studied in macular volumes of optical coherence tomography from 24 healthy volunteers and 19 patients with mild AD (Mini-Mental State Examination 23.42 ± 3.11). Results show that FD of retinal layers is greater in the AD group, the differences being statistically significant (p < 0.05). Correlation of layer FD with cognitive score, visual acuity and age reach statistical significance at 7 layers. Nearly all (44 out of 45) FD correlations among layers are positive and half of them reached statistical significance (p < 0.05). Factor analysis unveiled two independent factors identified as the dysregulation of the choroidal vascular network and the retinal inflammatory process. Conclusions: surface roughness is a holistic feature of retinal layers that can be assessed by the FD of their thickness maps and it is an early biomarker of AD.

Impacts of Camellia sinensis fermentation end-product (black tea) on retinal microvasculature: an updated OCTA analysis.

BACKGROUND: Tea, second only to water, is one of the most regularly consumed drinks in the world. Its potentially beneficial effects on general health may be enormously important. Optical coherence tomography angiography (OCTA) now allows clinicians to examine the acute retinal morphological changes caused by black tea consumption. The purpose of this study was to investigate the acute impacts of a Camellia sinensis fermentation end-product (black tea) on retinal microvasculature in healthy individuals using OCTA. RESULTS: In this study, 60 healthy people were divided into two groups: group 1 (n = 30) received black tea (2 mg/250 mL of water) and group 2 (n = 30) received only 250 mL of water. Following consumption, AngioVue Analytics software automatically analyzed the foveal, parafoveal, perifoveal macular superficial and deep vascular plexus densities, foveal avascular zone (FAZ) area, FAZ perimeter and foveal vessel density in a 300 µm wide region around the FAZ (FD-300). Male-to-female ratios were 19:11 and 15:15 in groups 1 and 2, respectively (P = 0.217). Mean age was 33.27 ± 7.92 years in group 1 and 31.00 ± 7.30 years in group 2 (P = 0.254). Changes in foveal, perifoveal and parafoveal macular vessel density between groups 1 and 2 were not statistically significant. In addition, no significant differences regarding FAZ, FAZ perimeter and FD-300 were observed. CONCLUSION: There were no acute effects of black tea on macular microcirculation in healthy individuals. The authors, however, believe that this study could serve as a model for future research on the relationship between regular tea consumption and general ocular physiology. © 2021 Society of Chemical Industry.