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The Journal of Experimental Biology Mar 2024Previous studies often inferred the focus of a bird's attention from its head movements because it provides important clues about their perception and cognition....
Previous studies often inferred the focus of a bird's attention from its head movements because it provides important clues about their perception and cognition. However, it remains challenging to do so accurately, as the details of how they orient their visual field toward the visual targets remain largely unclear. We thus examined visual field configurations and the visual field use of large-billed crows (Corvus macrorhynchos Wagler 1827). We used an established ophthalmoscopic reflex technique to identify the visual field configuration, including the binocular width and optical axes, as well as the degree of eye movement. A newly established motion capture system was then used to track the head movements of freely moving crows to examine how they oriented their reconstructed visual fields toward attention-getting objects. When visual targets were moving, the crows frequently used their binocular visual fields, particularly around the projection of the beak-tip. When the visual targets stopped moving, crows frequently used non-binocular visual fields, particularly around the regions where their optical axes were found. On such occasions, the crows slightly preferred the right eye. Overall, the visual field use of crows is clearly predictable. Thus, while the untracked eye movements could introduce some level of uncertainty (typically within 15 deg), we demonstrated the feasibility of inferring a crow's attentional focus by 3D tracking of their heads. Our system represents a promising initial step towards establishing gaze tracking methods for studying corvid behavior and cognition.
Topics: Animals; Crows; Eye-Tracking Technology; Motion Capture; Vision, Ocular; Visual Fields
PubMed: 38362616
DOI: 10.1242/jeb.246514 -
International Journal of Circumpolar... Dec 2024Retina fundus images conducted in Greenland are telemedically assessed for diabetic retinopathy by ophthalmological nurses in Denmark. Applying an AI grading solution,...
Retina fundus images conducted in Greenland are telemedically assessed for diabetic retinopathy by ophthalmological nurses in Denmark. Applying an AI grading solution, in a Greenlandic setting, could potentially improve the efficiency and cost-effectiveness of DR screening. We developed an AI model using retina fundus photos, performed on persons registered with diabetes in Greenland and Denmark, using Optos® ultra wide-field scanning laser ophthalmoscope, graded according to ICDR.Using the ResNet50 network we compared the model's ability to distinguish between different images of ICDR severity levels in a confusion matrix. Comparing images with ICDR level 0 to images of ICDR level 4 resulted in an accuracy of 0.9655, AUC of 0.9905, sensitivity and specificity of 96.6%.Comparing ICDR levels 0,1,2 with ICDR levels 3,4, we achieved a performance with an accuracy of 0.8077, an AUC of 0.8728, a sensitivity of 84.6% and a specificity of 78.8%. For the other comparisons, we achieved a modest performance. We developed an AI model using Greenlandic data, to automatically detect DR on Optos retina fundus images. The sensitivity and specificity were too low for our model to be applied directly in a clinical setting, thus optimising the model should be prioritised.
Topics: Humans; Artificial Intelligence; Diabetic Retinopathy; Diabetes Mellitus; Sensitivity and Specificity; Greenland; Mass Screening
PubMed: 38359160
DOI: 10.1080/22423982.2024.2314802 -
Journal of Visualized Experiments : JoVE Jan 2024Transplantation of photoreceptor cells and retinal pigment epithelial (RPE) cells provide a potential therapy for retinal degeneration diseases. Subretinal...
Transplantation of photoreceptor cells and retinal pigment epithelial (RPE) cells provide a potential therapy for retinal degeneration diseases. Subretinal transplantation of therapeutic donor cells into mouse recipients is challenging due to the limited surgical space allowed by the small volume of the mouse eye. We developed a trans-scleral surgical transplantation platform with direct transpupillary vision guidance to facilitate the subretinal delivery of exogenous cells in mouse recipients. The platform was tested using retinal cell suspensions and three-dimensional retinal sheets collected from rod-rich Rho::EGFP mice and cone-rich OPN1LW-EGFP;NRL mice, respectively. Live/dead assay showed low cell mortality for both forms of donor cells. Retinal grafts were successfully delivered into the subretinal space of a mouse model of retinal degeneration, Rd1/NS, with minimum surgical complications as detected by multimodal confocal scanning laser ophthalmoscope (cSLO) imaging. Two months post-transplantation, histological staining demonstrated evidence of advanced maturation of the retinal grafts into 'adult' rods and cones (by robust Rho::EGFP, S-opsin, and OPN1LW:EGFP expression, respectively) in the subretinal space. Here, we provide a surgical platform that can enable highly accurate subretinal delivery with a low rate of complications in mouse recipients. This technique offers precision and relative ease of skill acquisition. Furthermore, the technique could be used not only for studies of subretinal cell transplantation but also for other intraocular therapeutic studies including gene therapies.
Topics: Mice; Animals; Retinal Degeneration; Retina; Retinal Cone Photoreceptor Cells; Cell Transplantation; Vision, Ocular
PubMed: 38345250
DOI: 10.3791/65448 -
Optics Express Jan 2024We propose and design a multi-stage cascaded scanning laser ophthalmoscope (SLO) for ultra-wide field (UWF), which uses conicoid mirrors, constructed by conjugation of...
We propose and design a multi-stage cascaded scanning laser ophthalmoscope (SLO) for ultra-wide field (UWF), which uses conicoid mirrors, constructed by conjugation of pupil plane. The vergence uniformity and the angular magnification of a cascaded conicoid mirrors (CCM) system are analyzed recursively and optimized preliminarily to achieve high quality imaging with UWF, and the optimal system with the model eye are obtained by simulation and optimization. Two-stage and three-stage cascaded systems are designed with this method, and the formulas of beam vergence and angular magnification are obtained by theoretical derivation. As compared to the two-stage CCM system, the proposed three-stage cascaded UWF SLO has superior performance in imaging quality. Its average RMS radius of spot diagram is calculated to be 26.372 µm, close to the diffractive limit resolution. The image resolution of human retina can be up to 30 µm with 135° FOV in theory. The three-stage cascaded SLO is more suitable for UWF fundus imaging. This study will be helpful for early screening and accurate diagnosis of various diseases in the peripheral retina.
Topics: Humans; Ophthalmoscopy; Fundus Oculi; Retina; Ophthalmoscopes; Lasers
PubMed: 38297535
DOI: 10.1364/OE.508121 -
Applied Optics Jan 2024In prior art, advances in adaptive optics scanning laser ophthalmoscope (AOSLO) technology have enabled cones in the human fovea to be resolved in healthy eyes with...
In prior art, advances in adaptive optics scanning laser ophthalmoscope (AOSLO) technology have enabled cones in the human fovea to be resolved in healthy eyes with normal vision and low to moderate refractive errors, providing new insight into human foveal anatomy, visual perception, and retinal degenerative diseases. These high-resolution ophthalmoscopes require careful alignment of each optical subsystem to ensure diffraction-limited imaging performance, which is necessary for resolving the smallest foveal cones. This paper presents a systematic and rigorous methodology for building, aligning, calibrating, and testing an AOSLO designed for imaging the cone mosaic of the central fovea in humans with cellular resolution. This methodology uses a two-stage alignment procedure and thorough system testing to achieve diffraction-limited performance. Results from retinal imaging of healthy human subjects under 30 years of age with refractive errors of less than 3.5 diopters using either 680 nm or 840 nm light show that the system can resolve cones at the very center of the fovea, the region where the cones are smallest and most densely packed.
Topics: Humans; Calibration; Fovea Centralis; Lasers; Ophthalmoscopes; Refractive Errors; Retinal Diseases
PubMed: 38294386
DOI: 10.1364/AO.504283 -
Journal of Ophthalmic & Vision Research 2023This study aimed to report a case of peripapillary choroidal neovascularization (CNV) with a pitchfork sign.
PURPOSE
This study aimed to report a case of peripapillary choroidal neovascularization (CNV) with a pitchfork sign.
CASE REPORT
A young female presented with a progressive and painless visual blurring of the left eye. Ophthalmoscopic findings and results of optical coherence tomography (OCT), OCT angiography (OCTA), and fluorescein angiography (FAG) were evaluated. OCT showed subretinal hyperreflective material adjacent to the optic nerve head with multiple vertical finger-like projections extending into the outer retina (pitchfork sign). OCTA revealed that seafan-shaped high-flow vessels above the retinal pigment epithelium (RPE) were compatible with CNV type 2 with a large feeder vessel completely contiguous with the optic nerve. No evidence of ocular or systemic inflammation was found.
CONCLUSION
Pitchfork sign can be seen in CNV type 2 in either inflammatory or noninflammatory conditions.
PubMed: 38250232
DOI: 10.18502/jovr.v18i4.14557 -
BioMed Research International 2024[This retracts the article DOI: 10.1155/2022/5422360.].
[This retracts the article DOI: 10.1155/2022/5422360.].
PubMed: 38230043
DOI: 10.1155/2024/9820545 -
Biomedical Papers of the Medical... Jan 2024Large vessel carotid stenosis is a significant cause of ischaemic stroke. Indications for surgical revascularisation depend on the severity of the stenosis and clinical...
BACKGROUND
Large vessel carotid stenosis is a significant cause of ischaemic stroke. Indications for surgical revascularisation depend on the severity of the stenosis and clinical symptoms. However, mild symptoms such as TIA (Transient ischaemic attack), amaurosis fugax or minor stroke precede large strokes in only 15% of cases.
AIM
The aim of this prospective study is to evaluate whether retinal perfusion is impacted in significant carotid stenosis. Automated retinal oximetry will be used to better assess perfusion in the post-stenotic basin. We presume the more stenotic the blood vessel, the more reduced the retinal perfusion is, resulting in adaptive changes such as greater arteriovenous saturation difference due to greater oxygen extraction. This could broaden the indication spectrum for revascularisation for carotid stenosis.
METHODS
We plan to enroll yearly 50 patients with significant carotid stenosis and cross-examine them with retinal oximetry. The study group will provide stenotic vessels and, non-stenotic vessels will form the control group. Patients with significant carotid stenosis will undergo an MRI (Magnetic Resonnance imaging) examination to determine the presence of asymptomatic recent ischaemic lesions in the stenotic basin, and the correlation to oximetry parameters.
STATISTICS
The stenosis severity and retinal oximetry parameters will be compared for study and control groups with a threshold of 70%, respectively 80% and 90% stenosis. Results will be then reevaluated with emphasis on MRI findings in the carotid basin.
CONCLUSION
This prospective case control study protocol will be used to launch a multicentre trial assessing the relationship between significant carotid stenosis and retinal perfusion measured with automated retinal oximetry. Despite these differences, the findings indicate the potential of retinal oximetry for noninvasive real-time measurements of oxyhaemoglobin saturation in central nervous system vessels. Following calibration upgrade and technological improvement, verification retinal oximetry may potentially be applied to critically ill and anaesthesia care patients. The study on combined scanning laser ophthalmoscope and retinal oximetry supports the feasibility of the technique for oximetry analysis in newly born babies.
TRIAL REGISTRATION
ClinicalTrials.gov, ID: NCT06085612.
PubMed: 38192247
DOI: 10.5507/bp.2023.052 -
Graefe's Archive For Clinical and... May 2024To describe the benefits of optometric evaluation for detection of vision-affecting conditions in the context of community-based eye health screenings and identify...
PURPOSE
To describe the benefits of optometric evaluation for detection of vision-affecting conditions in the context of community-based eye health screenings and identify factors associated with having a recent dilated eye exam.
METHODS
Enrolled participants were age 40 and older, living independently in affordable housing developments in New York City. Eye health screening failure and criteria for seeing the on-site study optometrist were defined as visual acuity 20/40 or worse in either eye, intraocular pressure 23-29 mmHg, or an unreadable fundus image. The optometrist conducted a manifest refraction using loose lenses and used a portable slit lamp and ophthalmoscope to perform a non-dilated anterior and posterior segment ocular health evaluation. Demographics, social determinants of health, eye health screening results, and rates of suspected ophthalmic conditions were recorded. To determine factors associated with having a recent dilated eye exam, which was the main outcome for this statistical analysis, a stepwise multivariate logistic regression was performed.
RESULTS
A total of 708 participants were screened, 308 attended the optometric exam; mean age 70.7 ± 11.7 [standard deviation (SD)] years. Among this subgroup, 70.1% identified as female, 54.9% self-identified as African American, 39% as Hispanic/Latino, and 26.6% Dominican ethnicity; 78.2% (241/308) had not undergone a dilated eye exam within the last year, 71.4% reported they did not have an eye care provider. Stepwise multivariate logistic regression analysis indicated that participants who self-reported having cataracts (odds ratio (OR) 2.15; 95% confidence interval (CI) 1.03-4.47; p = 0.041), self-reported having glaucoma/glaucoma suspect (OR 5.60; 95% CI 2.02-15.43; p = 0.001), or spoke Spanish as their primary language (OR 3.25; 95% CI 1.48-7.11; p = 0.003) had higher odds of having a recent dilated eye exam.
CONCLUSIONS
This community-based screening initiative demonstrated the effectiveness of optometric exams in detecting vision-affecting conditions and identified factors associated with having a recent dilated eye exam. Optometrists play a vital role in increasing access to eye care for high-risk, underserved populations.
TRIAL REGISTRATION
ClinicalTrials.gov (NCT04271709).
Topics: Adult; Aged; Aged, 80 and over; Female; Humans; Middle Aged; Cataract; Follow-Up Studies; Glaucoma; Ocular Hypertension; Vision Disorders; Vision Screening
PubMed: 38189973
DOI: 10.1007/s00417-023-06344-2 -
BMC Ophthalmology Jan 2024To investigate the relationship between body weight and Axial length in guinea pigs.
BACKGROUND
To investigate the relationship between body weight and Axial length in guinea pigs.
METHODS
Forty pigmented guinea pigs were randomly divided into two groups, namely control group and negative lens-induced myopization (LIM) group. After measuring the baseline axial length and body weight (BW), guinea pigs of LIM group received bilateral negative lens-induced myopization using - 10.0 diopters lenses. One week later, the lenses were removed and biometric and ophthalmoscopic examinations were repeated.
RESULTS
Two groups of guinea pigs showed no statistical difference in initial body weight and eye axis length. Compared to the control group, the lens-induced group had a lower weight (P = 0.02) and a longer axial length (P < 0.01) at the end of study Neither at baseline nor at week 1 did AL correlate with BW in both groups (Control Baseline: r = 0.306, P = 0.19; Control Week1: r = 0.333, P = 0.15; LIM Baseline: r=-0.142, P = 0.55; LIM Week 1: r = 0.189, P = 0.42). Lens-induction had a significant effect on axial elongation (P < 0.01) while body weight had no impact on such aspect (P > 0.05).
CONCLUSION
In guinea pigs of the same age, axial length was not correlated with body weight. Also, baseline body weight had no impact on natural axial length growth or lens-induced myopia. Lens-induction caused a significant reduction in body weight gain.
Topics: Animals; Guinea Pigs; Myopia; Lens, Crystalline; Axial Length, Eye; Biometry; Disease Models, Animal
PubMed: 38172796
DOI: 10.1186/s12886-023-03271-y