We report the clinical history of two siblings, initially diagnosed with juvenile glaucoma (JG), who were subsequently found to harbor a novel pathogenic OPA1 splicing variant consistent with dominant optic atrophy (DOA). The male proband presented with elevated intraocular pressure (IOP) at age 11, while his sister had normal IOP values at age 16. Both developed bilateral temporal optic nerve pallor, central visual field defects, and reduced color vision. Optical coherence tomography (OCT) confirmed thinning of the retinal nerve fiber and ganglion cell layers. Whole exome sequencing identified a novel splice-site variant in OPA1 (NM_130837.3:c.611-2A>T) in both siblings and their affected mother, classified as pathogenic according to ACMG/AMP guidelines. During treatment washout, the male proband showed elevated IOP, consistent with concomitant JG and DOA, whereas the sister exhibited DOA only. This report highlights the importance of considering DOA in young patients with presumed JG, and suggests potential overlapping pathophysiology involving mitochondrial dysfunction and retinal ganglion cells vulnerability.

ABSTRACTFor species found in multiple habitats, the problem of camouflage against visually different backgrounds can be challenging. This is particularly so for bird eggs in open nests, as the scope for movement or alternative defensive strategies is limited. We studied egg camouflage in a small shorebird, the Kentish plover Anarhynchus alexandrinus, in two different coastal habitats in Cádiz province, Spain: sandy beaches and saltmarshes. Using calibrated photographs taken in situ and neurophysiologically plausible models of colour and pattern vision, we assessed the predicted discriminability of egg colour and patterning from those of backgrounds for likely nest predators (avian and mammalian carnivore) and, for comparison, humans. The findings suggest that at close range A. alexandrinus eggs are more susceptible to detection by visual predators based on their patterns (aka visual texture) rather than their colours, but at distances beyond which individual pattern elements can be resolved, they are highly cryptic. Although the colours and patterns of the saltmarsh and beach nest sites differ, the colours and surface patterning of eggs do not, suggesting that there is no local adaptation. However, the colours of eggs are similar to the types of background colours that overlap between the beach and saltmarsh. This suggests that, although the gross visual appearances of beach and salt marsh are quite different, egg camouflage in Kentish plovers relies on behavioural nest‐site selection and a good colour match to the average location type. The maculation on the eggs does not appear to represent background matching in terms of pattern, so its function remains speculative.

An optimal visual environment in operating rooms (ORs) is critical for ensuring safe effective patient care. This study's primary objective assessed-in a simulated environment-OR staff task performance under spectrally shifted (blue and green) ambient lighting conditions, commonly used in minimally invasive surgical procedures, by comparing success rates, error rates and completion times to that under white light. Secondary objectives included identifying drug label features most relied on for accurate decision-making under these lighting conditions. This randomized-single-center-crossover trial involved 300 OR staff and volunteers at the Royal Brisbane and Women's Hospital. Participants were screened for color vision deficiencies using the Ishihara and Farnsworth D-15 Tests (FT), then randomized to 1 of 2 lighting sequences (blue-green or green-blue). Each participant completed the FT and Drug Label Matching Test (DLMT) under each lighting condition, with performances compared to white light. A questionnaire assessed which drug label characteristics participants used for identification under each lighting condition. Of the 266 eligible participants, all successfully completed the FT under white light (100% success; 95% confidence interval [CI], 99.01%-100%), but none succeeded under blue/green light (0% success; 95% CI, 0.00%-0.99%). Median FT completion times were 50 (interquartile range [IQR], 39-63) seconds (white), 64 (IQR, 49-84) seconds (blue), and 64 (IQR, 44-93) seconds (green). Median DLMT completion times were 76 (IQR, 65-89) seconds (white), 103 (IQR, 88-126) seconds (blue), and 96 (IQR, 78-120) seconds (green), with significantly faster performance under white light compared to blue or green ( P < .001 for both). DLMT failure rates were significantly higher ( P = .033) under blue/green light compared to white, with the odds of an error occurring under blue/green light estimated to be 3.67 times higher (95% CI, 1.05-12.87). Under blue and green light, reliance on color for drug identification dropped sharply (from 96.6% to ~41%-42.5%), while use of drug names differed slightly (76.3% to ~80%-83%), grouping (8.3% to ~50%-56.8%) and memory (0.4% to ~42%-45%) both increased substantially. This study demonstrated that ambient blue and green lighting significantly impairs the ability of OR staff to distinguish color hues, compromising color-dependent decision-making. The Farnsworth D-15 Test confirmed that color hues become virtually indistinguishable under spectrally shifted lighting. Drug Label Matching Test performance declined to a lesser extent due to the presence of multiple identifiers on drug labels with increased reliance on noncolor cues. These findings underscore potential challenges in accurately assessing tissue perfusion and identifying medications, thereby elevating risks of medication errors. To address these concerns, strategies such as improved environmental lighting control, use of machine-readable drug labeling, or integration of augmented reality tools should be considered. Further research is warranted to explore clinical implications of spectrally shifted lighting and to evaluate solutions in real-world perioperative settings.

PurposeSinonasal mucosal melanoma (SNMM) accounts for approximately 4-8% of sinonasal malignancies. SNMM frequently originates in the nasal cavity, causing nonspecific nasal symptoms that inevitably delay diagnosis. Left untreated, the tumor may extend into the orbit.Case DescriptionHerein, the authors describe two patients presenting with compressive optic neuropathy and were found to have advanced SNMM involving the orbit. Both patients presented with vision loss, decreased color vision, proptosis, conjunctival chemosis, and restricted extraocular movements. One patient was found to have a relative afferent pupillary defect. Neither patient was a surgical candidate, and both received palliative radiotherapy and immunotherapy.ConclusionsThese cases and literature review demonstrate the potential for the disease to initially manifest with orbital extension and ocular symptoms. Ophthalmologists can play a crucial role in the early detection of SNMM, which may improve outcomes, given the challenges of SNMM treatment.

Background Cataract is the leading cause of reversible blindness worldwide, affecting visual function through different morphological types. Nuclear sclerosis often reduces distance vision with myopic shift, cortical cataract commonly causes glare and variable acuity, while posterior subcapsular cataract disproportionately impairs best-corrected visual acuity. Evaluating these differences in visual function is important for patient counseling and surgical planning. This study analyzes visual acuity, contrast sensitivity, color vision and glare among patients with nuclear, cortical, and posterior subcapsular cataracts. MethodsA cross-sectional study was conducted among 395 patients (131 per cataract type) at Lumbini Eye Institute, Nepal. Cataract grade was assessed using LOCS III, and visual function evaluated with Snellen’s chart (VA), Ishihara chart (color vision), Pelli-Robson chart (contrast sensitivity), and Glare and Halo Questionnaire.ResultsAmong 395 patients (52.2% female), mean logUCVA was worst in nuclear sclerosis (0.94±0.35) and best in cortical cataract (0.76±0.33; p-value&lt;0.001), while logBCVA was poorest in PSCC (0.61±0.31; p-value&lt; 0.001). NS showed myopic, CC hyperopic, and CC had highest astigmatism (p-value=0.008). Contrast sensitivity was highest in CC and lowest in PSCC (p-value=0.015). Glare increased with cataract grade, most frequent in PSCC (92%). Color vision remained normal in &gt;96% of all groups (p-value=0.66).Conclusions Visual function varied among cataract types, with nuclear sclerosis showing worse UCVA, posterior subcapsular cataract worse BCVA, cortical cataract higher contrast sensitivity, and glare increasing with cataract grade, while color vision remained largely unaffected.

Purpose: A 12-year-old boy with a five-day history of blunt trauma to the right orbit was referred to our pediatric ophthalmology clinic for evaluation of diplopia and proptosis.Case summary: Upon examination, uncorrected visual acuity was 20/20 in both eyes, intraocular pressures were 19 mmHg and 16 mmHg in the right and left eye, respectively, and Hertel exophthalmometry revealed 2 mm of right eye proptosis. Extraocular motility testing demonstrated 16 prism diopters (PD) of right exotropia and 2 PD of right hypotropia in primary position, with restricted upgaze in the right eye. Pupillary reflexes, color vision, slit-lamp biomicroscopy, and fundus examination were normal. Orbital computed tomography (CT) showed a subperiosteal hematoma compressing the right superior rectus muscle. The patient was managed conservatively, with resolution of upgaze limitation within six months. Follow-up CT at nine months demonstrated complete hematoma resolution without residual orbital mass.Conclusions: Spontaneous resolution of post-traumatic orbital subperiosteal hematoma is rare but possible; in the absence of compressive optic neuropathy, careful observation with regular follow-up should be considered.

Color vision assessment is essential in clinical practice, yet different tests exhibit distinct strengths and limitations. Here we apply a psychophysical paradigm, Angular Indication Measurement (AIM) for color detection and discrimination. AIM is designed to address some of the shortcomings of existing tests, such as prolonged testing time, limited accuracy and sensitivity, and the necessity for clinician oversight. AIM presents adaptively generated charts, each a N×M (here 4 × 4) grid of stimuli, and participants are instructed to indicate either the orientation of the gap in a cone-isolating Landolt C optotype or the orientation of the edge between two colors in an equiluminant color space. The contrasts or color differences of the stimuli are adaptively selected for each chart based on performance of prior AIM charts. In a group of 23 color-normal and 15 people with color vision deficiency (CVD), we validate AIM color against Hardy-Rand-Rittler (HRR), Farnsworth-Munsell 100 hue test (FM100), and anomaloscope color matching diagnosis and use machine learning techniques to classify the type and severity of CVD. The results show that AIM has classification accuracies comparable to that of the anomaloscope, and while HRR and FM100 are less accurate than AIM and an anomaloscope, HRR is very rapid. We conclude that AIM is a computer-based, self-administered, response-adaptive and rapid tool with high test-retest repeatability that has the potential to be suitable for both clinical and research applications. Not applicable.

Retinitis pigmentosa (RP) is the most common group of hereditary retinal disorders, characterised by the progressive degeneration of photoreceptor cells in the retina, leading to gradual loss of vision. Rod dysfunction causes night blindness and peripheral visual loss, followed by cone involvement affecting central and colour vision.

Introduction: Vision plays a critical role in maintaining quality of life, particularly among elderly individuals. Senile cataracts, a leading cause of visual impairment in older adults, can significantly hinder daily functioning and vision-related quality of life (VRQL). Although phacoemulsification surgery is the standard treatment, its broader impact on functional independence and VRQL warrants further exploration. Purpose: This study aimed to evaluate changes in activities of daily living (ADL) and VRQL in patients with senile cataracts before and after undergoing phacoemulsification surgery. Methods: An analytic cross-sectional study was conducted using purposive randomized sampling. ADL was assessed using the Barthel Index, while VRQL was measured using the National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25). The Marginal Homogeneity test was applied to analyze changes in ADL, and the Wilcoxon test was used to analyze VRQL data. Results: The study included 50 patients with a mean age of 65.9 ± 9.6 years, of whom 42% were male and 58% female. Of the participants, 58% had immature cataracts, and 42% had mature cataracts. There was a significant improvement in ADL post-surgery (p = 0.000). Preoperatively, 50% of the patients were severely dependent, 40% were moderately dependent, and 10% were mildly dependent. Postoperatively, 82% of the patients became independent, 14% mildly dependent and 4% moderately dependent. VRQL also showed significant improvements across domains, including overall function, visual acuity, near vision, distance vision, and color vision (p = 0.000). Conclusion: Phacoemulsification surgery in patients with senile cataract significantly enhances both functional independence in daily living and vision-related quality of life.

To report two cases of Jalili syndrome (JS) harboring a novel mutation in the CNNM4 gene, review previously published studies on JS, and analyze factors potentially associated with visual acuity in patients with JS. Two JS patients from a non-consanguineous Chinese family underwent comprehensive ophthalmic evaluations. Next-generation sequencing (NGS) was performed to identify pathogenic variants, and Sanger sequencing was used for validation. A literature search was conducted to retrieve studies on JS published up to January 31, 2025; only studies with detailed records of visual acuity and mutation sites were included. Correlations between visual acuity and age, as well as between visual acuity and mutation domain, were analyzed. A total of 53 patients with detailed visual acuity and mutation site records from previous studies were included in the analysis. The mean logarithm of the minimum angle of resolution (logMAR) visual acuity was 1.15 (range: 0.69-2.00). Spearman's correlation analysis showed a positive correlation between visual acuity (logMAR) and age (rs =0.502, P<0.001). No association was found between logMAR visual acuity and mutation domain (P=0.748). The 6-year-old proband and her 3-year-old brother carried a novel homozygous missense variant c.949A>C (p.Ser317Arg) in CNNM4. Both patients presented with reduced visual acuity, pendular nystagmus, photophobia, night blindness, color vision loss, macular atrophy, and amelogenesis imperfecta. Optical coherence tomography (OCT) revealed atrophy of the outer retinal layers, and electroretinography (ERG) showed extinguished cone and rod responses. Fundus autofluorescence (FAF) and fundus fluorescein angiography (FFA) of the proband demonstrated bilateral retinal pigment epithelium (RPE) defects around the optic disc, vascular arcades, and macular region. At the latest follow-up (30mo), the proband's condition remained stable: best-corrected visual acuity was 2.00 logMAR (right eye) and 1.30 (left eye), with no changes in fundus appearance. The younger brother had a best-corrected visual acuity of 1.52 logMAR in both eyes at the latest follow-up, accompanied by severe bilateral macular atrophy and obvious dentin discoloration due to progressive enamel thinning. This study reports a novel homozygous missense variant c.949A>C (p.Ser317Arg) in CNNM4 in a Chinese JS family. Visual acuity in JS patients deteriorates with increasing age.

Introduction: Due to optic nerve and retinal damage, methanol-induced optic neuropathy (Me-ION) may lead to permanent vision loss, including blindness, making it a serious condition. Here, we present a case demonstrating clinical recovery in a patient with Me-ION. Case Presentation: A 20-year-old man came to the emergency unit with a chief complaint of sudden visual loss in both eyes since the day before admission. It was accompanied by shortness of breath, headache, nausea, and vomiting. He reported ingesting methanol three days before presentation and had no history of systemic illness. Visual acuity (VA) was counting fingers at one meter in the right eye and counting fingers at three meters in the left eye. The intraocular pressure (IOP) in both eyes was measured at 12.2 mmHg. Optical Coherence Tomography (OCT) of the retinal nerve fiber layer (RNFL) revealed increased thickness in both superior and inferior quadrants bilaterally. Laboratory tests revealed metabolic acidosis. The patient was diagnosed with Me-ION in both eyes, accompanied by metabolic acidosis. Dialysis was started, and he was treated with a high-dose steroid. Subsequently, VA improved to 5/5 in the right eye and 5/12 in the left eye. Color vision improved in the right eye to 30/38 (Ishihara), while the left eye remained at 20/38. Conclusions: Early diagnosis and prompt treatment of Me-ION can result in significant clinical improvement in visual acuity and color vision, emphasizing the significance of early treatment in managing toxic optic neuropathy.

Quantitative data on the colors of early film productions is very scarce but may be useful for preserving these cultural assets and for guiding modern digitization processes. We measured the spectral transmittance of 46 small areas in 13 frames of films from the 1910s and 1920s, which were colored using the same tinting process. From spectral measurements of the light source in an early carbon arc cinema projector, we computed CIELAB color coordinates for these areas and the results were compared with those from two more recent light sources: a Xenon lamp and an ultra-high performance (UHP) lamp. Average color inconstancy values for the 46 samples were 3.5, 7.9, and 7.0 CIELAB units for carbon-Xenon, carbon-UHP and Xenon-UHP changes, respectively, which are color differences above human visual thresholds for observers with normal color vision. Therefore, for accurate color specifications of such films, in addition to the spectral transmittances of frames, we must consider the spectral power distribution of projection lamps. Compared with a recent surface object-color gamut, the 46 samples were spread across a relatively wide region of color space, excluding CIELAB hue-angles in the range of 270–360 degrees.

To report TON in indigenous tribal communities of Northeast India, and to explore its association with Tuibur use. Retrospective study undertaken in consecutive patients presenting with unexplained gradual, painless, bilateral diminution of vision. Detailed dietary and medical history was taken. Demographic profile of subjects was noted, including age, gender, ethnicity and occupation. Duration & frequency of Tuibur use per day was noted. Clinical evaluation along with visual fields, color vision, Retinal nerve fibre layer analysis was done. All patients were started on oral Vitamin B complex supplementation, including Vitamin B12 (1500 mcg) once daily for three months. The patients were called for follow up at monthly intervals for 3 months and at 6 months. 39 patients with bilateral involvement, mean age of 39.5 ± 11.6 years were studied. 82% were females; 97.4% belonging to tribal community. There was statistically significant improvement in visual acuity [Oculus Dexter (OD) P=0.002, Oculus Sinister (OS) P=0.007] and visual field indices after treatment. TON may cause severe visual loss; however, timely management gives favourable results. Treatment involves replacing deficient nutrients and eliminating offending toxins. It is also important to consider contributory cultural and dietary practices. This is the first study linking a hitherto unheard-of toxic agent, liquid tobacco (Tuibur/Hidakphu) to optic neuropathy.

Color vision deficiency (CVD) affects learning outcomes, career opportunities, and daily life, but early screening in Vietnam remains limited. This study introduces an Android-based mobile health (mHealth) application for CVD screening, integrated with an artificial intelligence (AI) module for career guidance. The app was deployed with 527 high school students in Da Nang and validated against standard printed Ishihara plates. Results showed complete agreement with the traditional test, faster screening time, and positive feedback on ease of use and usefulness. The majority of students rated the CVD simulation and career guidance functions as valuable. This research contributes by (1) validating a CVD mHealth tool on a large student population in real educational settings, (2) integrating AI to link health screening with career orientation, and (3) demonstrating a cost-effective, scalable digital solution that supports both school health programs and personalized career counseling. The findings emphasize the role of engineering innovations in enhancing education and health support for students.

BackgroundMobile visual acuity (VA) apps have emerged as valuable tools in both clinical and home settings, particularly in the context of expanding teleophthalmology. Despite the growing number of apps available to measure visual acuity, studies evaluating their overall quality, functionality, and clinical relevance are limited.ObjectiveThis study aimed to systematically evaluate the quality and features of mobile VA apps available on iOS and Android platforms using the clinically validated Mobile App Rating Scale (MARS).MethodsA comprehensive search of the Google Play Store and Apple App Store was conducted between January 2024 and March 2024 using standardized search terms. Eligible apps included free, English-language VA testing tools not requiring external devices. App characteristics and features were extracted. Each app was independently evaluated by 2 trained reviewers using MARS, which rates engagement, functionality, aesthetics, information quality, and subjective quality on a 5-point scale.ResultsOf the 725 apps initially identified, 44 met the inclusion criteria, with 23 from the Google Play Store and 21 from the Apple App Store. The most common VA test optotypes used were Tumbling E (n=21; 48%), Snellen Chart (18/44; 41%), and Landolt C (n=14; 32%). Common supplemental features included color vision testing (n=20; 46%), astigmatism tests (n=13; 30%), Amsler grid (n=13; 30%), and contrast testing (n=12; 28%). The average MARS scores were comparable across platforms: 3.04 (SD 0.80) for Android and 3.02 (SD 0.84) for iOS. Functionality received the highest ratings (mean 3.65, SD 0.75 for Android; mean 3.71, SD 0.82 for iOS), while subjective quality received the lowest (mean 2.09, SD 1.01 for Android; mean 2.21, SD 1.01 for iOS). Few apps had undergone clinical validation. Only Apple App Store apps demonstrated significant correlations between MARS scores and app store star ratings.ConclusionsVA apps exhibited considerable heterogeneity in quality, functionality, and clinical use. Total mean MARS scores were similar between the Google Play Store and the Apple App Store, suggesting that neither platform consistently offers superior app quality. While many apps are technically sound, low subjective-quality scores and a lack of clinical validation limit their current use in professional practice. These findings underscore the need for more rigorous app development and validation standards to improve their relevance and reliability in teleophthalmology.

Daltonization methods are image adaptation techniques that adjust screen colors to aid people with color vision deficiency (CVD). Though their effectiveness in boosting the hue’s dissimilarity has been documented, it was not entirely clear to what extent they improve color processing. The purpose of our study was to measure the direct contribution of daltonization to color working memory. Two different types of daltonization methods were tested: severity–based (SB) enhancing red-green contrast and type-based (TB) enhancing blue-yellow contrast. We used simple behavioral tasks while measuring speed and accuracy. Participants in our experiments were asked to find the target color among the two presented choices (2AFC task). The colors were either presented simultaneously (perception task) or sequentially (memory task). Both daltonization methods significantly improved CVD participants’ performance on both tasks and with both measures, with stronger effects found in the memory task. The effects of the TB method were robust across tasks, while the effects of the SB method were smaller and dependent on the level of enhanced red-green contrast when colors needed to be remembered. We confirmed the previously reported effects of daltonization and demonstrated that these effects extend to the level of short-term retention of color information. Based on the differences in the effects of the two daltonization methods under varying cognitive demands, we identified the specific conditions under which each method supports cognitive functions. Consequently, our findings enable precise application decisions: using daltonization for promoting fast discrimination vs. enhancing memory during material learning.

Non-motor symptoms of Parkinson's disease (PD), particularly visual disturbances, often appear before a formal diagnosis and may serve as early signs or prodromal features of the disease. This review aims to evaluate ocular biomarkers associated with prodromal and early-stage PD, highlighting ophthalmic indicators that could support earlier diagnosis and aid in tracking disease progression. PubMed and Scopus databases were systematically searched for all records available from their inception through May 2024, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement extension for Scoping Reviews (PRISMA-ScR) guidelines. Two distinct PICO (PICO stands for Population, Intervention, Control, Outcome) frameworks were employed to guide the selection criteria: one for people with early Parkinson's disease and another for individuals at risk of prodromal PD. 30 studies were included - 4 solely on prodromal cohorts (RBD), 18 on patients with PD and 8 studies with both prodromal and clinical cohorts. Studies of people with RBD have shown abnormalities in pupillary light reflex, eye movements, and color discrimination. People with early PD showed impaired contrast sensitivity, impaired color discrimination, retinal structural changes, including retinal thinning (in the inner nuclear layer and ganglion cell-inner plexiform layer, altered pupillary responses, visual hallucinations, and ocular movement disorders). Impairment of both color and contrast vision, as well as changes in optical coherence tomography (OCT), correlate with disease severity and cognitive decline. They can serve as an early, safe, noninvasive biomarker of neurodegeneration.

The KeyScope (KS) is a low-cost laparoscope that is designed specifically for use in low- and middle-income countries (LMICs). This study evaluates its safety and feasibility in a porcine model. Surgeons performed three laparoscopic tasks fundamental to the performance of laparoscopy, including stapled bowel resection, intracorporeal knot tying, and cholecystectomy in three pigs: a practice pig, KS, and standard-of-care (SOC). Vital signs, complications, and task completion times were compared using paired nonparametric tests. After completing laparoscopic tasks, surgeons completed a survey to assess feasibility and identify opportunities for technology improvement. Five surgeons completed 45 laparoscopic tasks in 15 animals. There were no significant differences in vital signs between KS and SOC. There were no significant differences in median times to perform stapled bowel resection or cholecystectomy (KS 3min, SOC 3min, p = 0.185; KS 6min, SOC 8min, p = 0.887, respectively). Surgeons performed intracorporeal knot tying on SOC significantly faster than KS (KS 5min, SOC 3min, p = 0.012). All surgeons entered the gallbladder during dissection, with more liver bed injuries using the SOC compared to KS (n = 3, 60% vs. n = 2, 40%). Surgeons reported they would be willing to use the KS for laparoscopic procedures they do not routinely perform. When asked to rate the performance of KS versus SOC, there was a preference for KS in ergonomics and degree of fogging but a preference for SOC for light intensity, distance vision, and amount of focus. They felt KS and SOC performed similarly in glare, tissue color, and close vision. Surgeons reported a preference for the KS to an open approach. In standardized porcine studies, KS performed similarly to the SOC with fewer complications, demonstrating both its feasibility and safety. Overall, surgeons reported comfort using the KS for laparoscopic cases. This data supports that KeyScope is a feasible tool to enable laparoscopy in LMICs.

PurposeThe primary aim of this study was to evaluate the level of agreement in color vision assessment between the smartphone application Farnsworth D-15 (FD-15) test and the standard FD-15 test.Materials and MethodsA cross-sectional study was conducted involving participants aged ≥ 18 years. Inclusion criteria included the ability to follow test instructions and provide informed consent. Eyes with visual acuity worse than 20/200 were excluded. Standardized score sheets were used for both tests to calculate the color confusion index (CCI). Agreement between the two tests was assessed using the Pearson correlation coefficient, adjusted R-squared (R2), calibration slope, calibration-in-the-large (CITL), and root mean square error (RMSE), and Bland–Altman plots.ResultsA total of 200 eyes from 101 participants were included in the study. The CCI data showed a strong correlation (Pearson correlation coefficient = 0.9924). The adjusted R2 of 0.9839 indicated high explanatory power. A calibration slope of 0.9861 and CITL of 0.0957 indicated minimal proportional and systematic bias, respectively. RMSE was 0.1211, within acceptable limits. The Bland–Altman analysis demonstrated limits of agreement within clinically acceptable range.ConclusionThe smartphone application FD-15 test demonstrated high agreement with the standard FD-15 test. This study serves as a pilot validation demonstrating the potential of the smartphone-based FD-15 application for color vision screening. However, the current findings should be interpreted considering the use of a single smartphone model and the low prevalence of color vision defects. These findings support its potential utility as a practical and accessible tool for remote care and occupational health assessments.

In primates, the OFF midget retinal ganglion cells (OFF mRGCs) have a high spatial density and small dendritic arbors. Their axons provide input to the parvocellular pathway mediating both colour vision and the highest-acuity spatial vision. This study aimed to understand the basis for their light responses by identifying the presynaptic amacrine and bipolar cells. Retinal tissue from an adult macaque was processed for serial block-face scanning electron microscopy, and a volume of images of the inner retina located 2mm temporal to the centre of the fovea was analysed. Ten OFF mRGCs and many of their presynaptic cells were reconstructed. Both midget and diffuse types of bipolar cells provided excitatory, glutamatergic input. Axons and long dendrites of wide-field amacrine cells made synapses, and we propose that these mediate tonic, GABAergic inhibition. Narrow-field amacrine cells also made synapses onto the OFF mRGCs, and we propose that most of them are glycinergic, inhibitory synapses. One presynaptic narrow-field amacrine cell was the knotty bistratified type 1 (KB1), which contains immunoreactive glycine and vesicular glutamate transporter 3. We propose that they enlarge the receptive field centers of OFF mRGCs via direct, excitatory synapses. The KB1 cell studied most extensively was presynaptic to some of the same types of amacrine cells that made inhibitory synapses onto OFF mRGCs. We propose that the knotty bistratifed type 1cells release glycine at those synapses and disinhibit responses of OFF mRGCs. KEY POINTS: In primates, OFF midget ganglion cells have the highest spatial density of any projection neurons, and they mediate high acuity vision. Ten of these cells and the neurons providing their inputs were reconstructed from a volume of serial ultrathin sections taken 2mm temporal to the centre of the macaque fovea. They received the majority of their inputs from amacrine cells, local circuit neurons that are typically inhibitory. One of the presynaptic amacrine cells resembled those containing vesicular glutamate transporter 3, and we propose that they provide excitatory input that enlarges the receptive field centers of OFF midget ganglion cells. They also receive excitatory input from both midget and diffuse bipolar cells. The results provide an explanation for some apparent contradictions between anatomical and physiological studies and are potentially important for understanding the etiology of retinal diseases.