Search Results (1,465)

Objectives: Fluorescein break-up time (FBUT) is commonly used to assess tear film stability. However, the instillation of fluorescein destabilises the tear film, impacting validity and clinical applicability, while the subjective nature and variation in volume and concentration reduces repeatability. Non-invasive break-up time (NIBUT) offers an alternative method with less potential bias. Normal tear break-up time is conventionally accepted as 10 seconds (s); however, FBUT is expected to be lower than NIBUT. This study was designed to compare FBUT and NIBUT values in a pre-operative refractive surgery population, where diagnosis of dry eye disease may alter the risk–benefits ratio and contraindicate surgical procedure(s). Improved understanding of the relationship between these two methods will aid appropriate pre-operative patient counselling and consent. Methods: Data from consecutive participants presenting to a private ophthalmology clinic, for initial refractive surgery pre-operative assessment, were analysed. NIBUT and FBUT were performed. Paired and unpaired comparisons were made using the Wilcoxon signed-rank and Mann–Whitney U tests, respectively, and relationships with demographics were explored using Spearman’s rank correlation coefficient. Results: Median and interquartile range (IQR) for the first NIBUT was 12.5 s (7.0–18.0 s) and 14.2 s (9.4–18.0 s) for the right and left eyes, respectively. Median and IQR for the average NIBUT was 14.0 s (6.9–18.0 s) and 14.6 s (10.1–18.0 s) for the right and left eyes, respectively. Median and IQR for FBUT was 7 s (5–8 s) and 6 s (5–8 s) for the right and left eyes, respectively. There was a statistically significant difference between NIBUT and FBUT (p < 0.001). Conclusions: The findings suggest that the commonly used diagnostic threshold of 10 s cannot be uniformly applied to both FBUT and NIBUT, as FBUT systematically underestimates tear stability. Full article

Background/Objectives: Attention deficit hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder. As the retina is an extension of the central nervous system, retinal imaging may provide insights into the ADHD pathophysiology. The objective of this work was to evaluate structural retinal alterations using optical coherence tomography (OCT) in ADHD patients compared to neurotypical controls. Methods: A case–control study involving 200 eyes (100 from 50 patients with ADHD and 100 from 50 controls) was conducted by comparing the thicknesses of the macular region (total retina, inner and outer retinal layers, ganglion cell layer plus inner plexiform layer [GCIPL], and macular retinal nerve fiber layer [mRNFL]), the peripapillary region (pRNFL), and the optic nerve head (ONH) parameters. Areas under the curve (AUCs) were calculated to evaluate diagnostic performance. Right and left eyes were analyzed separately. Results: Patients with ADHD showed a significant reduction in total and outer retinal thickness across several macular sectors in both eyes. No significant differences were observed in mRNFL, GCIPL, inner retina, pRNFL, or ONH parameters between groups. AUC values derived from ROC analysis indicate moderate diagnostic performance for total and outer retinal thickness in the macular region. Conclusions: ADHD is associated with retinal thinning in the macula (total and outer retinal thickness) in both eyes, suggesting the potential of OCT-based biomarkers for this condition. Full article

Background/Objectives: Autorefractometers are valuable tools in clinical practice, but their accuracy is often questioned, especially in the pediatric population. This study aimed to compare refraction data from open-field and close-field autorefractometers and subjective refraction without using cycloplegia. Methods: A total of 50 eyes of 50 participants (19 males and 31 females, 11.8 ± 1.56 years) were evaluated. In a single visit, objective refraction was performed using NVision-K 5001 (open-field) and Visionix VX120 (close-field) autorefractometers, and subjective refraction using the fogging technique. Differences between procedures were assessed for sphere, spherical equivalent, and cylindrical vectors J₀ and J₄₅ using the Friedman test, followed by the post hoc Wilcoxon test as needed. Results: Significant differences were found in the sphere between the three procedures (all p ≤ 0.032). For the spherical equivalent, the Visionix VX120 differed significantly with the other two techniques (both p < 0.001), whereas no significant differences were found between NVision-K 5001 and subjective refraction (p = 0.193). Finally, no significant differences were observed for J₀ and J₄₅ vectors among the procedures (both p ≥ 0.166). Conclusions: There are certain discrepancies between autorefractometers and the subjective assessment of refractive error, most evident in measurements taken with the close-field device, possibly due to greater accommodative stimulation. However, in contexts such as visual screening or as a preliminary guide in the clinic, the values obtained by autorefractometry can provide useful information. Full article

Background: Early identification of visual disorders in children is essential to prevent long-term visual impairment and support academic development. Despite the recognized importance of visual screenings, no universal consensus exists on which visual parameters or threshold values should be used, particularly for measuring visual acuity (VA) in pediatric populations. Objectives: This study aimed to develop age-related percentile norms for VA using LEA symbol charts. Methods: A sample of Italian schoolchildren aged 5 to 15 years (n = 1510) participated in the study. Data were collected retrospectively from school-based vision screenings conducted across 12 schools in the Lombardy and Piedmont regions from 2010 to 2019. Monocular and binocular VA were measured at 3 m using a standardized LEA symbol chart, and values were scored letter-by-letter on a LogMAR scale. Smoothed percentile curves were derived using Box–Cox, Cole, and Green distribution modeling and regression analysis. Results: The results showed a non-linear improvement in VA with age. Compared to prior studies, LEA symbols yielded slightly lower VA scores, reinforcing the need for chart-specific norms. The 50th percentile VA improved from approximately +0.07 LogMAR at age 6 to about −0.09 LogMAR at age 15. Conclusions: These findings highlight the importance of age-specific, chart-specific, and statistically robust reference data for VA screening in children. The derived percentile tables offer a more sensitive tool than fixed cut-offs for identifying visual anomalies and tailoring clinical interventions. This work contributes to standardizing pediatric VA screening practices and improving early detection of visual deficits. Full article

Background: Standard visual acuity (VA) is often preserved in early retinitis pigmentosa (RP), limiting its value as a marker of functional impairment. Alternative measures such as low-luminance deficit (LLD) and low-contrast deficit (LCD) may detect earlier changes in cone function. This study aimed to evaluate the diagnostic utility of these measures in RP patients under photopic and mesopic conditions. Methods: A prospective observational study was conducted on 57 RP patients and 54 age-matched controls. Binocular VA was assessed using ETDRS charts at 100% and 10% contrast under photopic (100 cd/m²) and mesopic (1 cd/m²) conditions. LLD and LCD scores were computed from VA differences across conditions. ROC curve analysis was used to determine diagnostic accuracy. Results: RP patients showed significant VA loss under reduced luminance and contrast (p < 0.001), independent of age. LLD under high contrast was reduced, while LLD under low contrast and LCD (both photopic and mesopic) were significantly higher than in controls. The mesopic LCD demonstrated the highest diagnostic capacity (AUC = 0.87), with a threshold of > 13 ETDRS letters yielding optimal sensitivity and specificity. Unlike standard VA, mesopic LCD correlated with functional symptoms and was unaffected by age. Conclusions: Low-contrast VA under mesopic conditions is a simple, reproducible, and sensitive marker for early visual dysfunction in RP. A difference > 13 ETDRS letters may serve as a clinically relevant threshold for disease monitoring and early detection in retinal dystrophies. Full article

Spectral-domain Optical Coherence Tomography (SD-OCT) is a critical tool in ophthalmology, providing high-resolution cross-sectional images of the retina. Accurate segmentation of sub-retinal layers is essential for diagnosing and monitoring retinal diseases. While manual segmentation by clinicians is the gold standard, it is subjective, time-intensive, and impractical for large-scale use. This study introduces an automated segmentation algorithm based on graph theory, utilizing a shortest-path graph-search technique to delineate seven intra-retinal boundaries. The algorithm incorporates a region of interest (ROI) selection to enhance efficiency, achieving a mean computation time of 0.93 s on standard systems suitable for real-time clinical applications. Image denoising was evaluated using Gaussian and wavelet-based filters. While wavelet-based denoising improved accuracy to some extent, its increased computation time (~10 s/image) was the trade-off. The intra-retinal layer thicknesses computed by the segmentation algorithm was consistent with previous studies and demonstrated high accuracy with respect to manual segmentation, thus indicating clinical relevance. Future research will explore integrating machine learning to improve robustness across diverse retinal pathologies, enhancing the algorithm’s applicability in clinical settings. Full article

Background: In glaucoma screening programs, a large proportion of patients remain free of open-angle glaucoma (OAG) or have no need of intraocular eye pressure (IOP)-lowering therapy within 10 years of follow-up. Is it possible to identify a large proportion of patients already at the initial examination and, thus, to safely exclude them already at this point? Methods: A total of 6889 subjects received a complete ophthalmological examination, including objective optic nerve head and quantitative disc measurements at the initial examination, and after an average follow-up period of 11.1 years, complete data were available of 585 individuals. Two neural network models were trained and extensively tested. To allow the models to refuse to make a prediction in doubtful cases, a reject option was included. Results: A prediction for the first endpoint, ‘remaining OAG-free and no IOP-lowering therapy within 10 years’, was rejected in 57% of cases, and in the remaining cases (43%), 253/253 (=100%) received a correct prediction. The second prediction model for the second endpoint ‘remaining OAG-free within 10 years’ refused to make a prediction for 46.4% of all subjects. In the remaining cases (53.6%), 271/271 (=100%) were correctly predicted. Conclusions: Most importantly, no eye was predicted false-negatively or false-positively. Overall, 43% all eyes can safely be excluded from a glaucoma screening program for up to 10 years to be certain that the eye remains OAG-free and will not need IOP-lowering therapy. The corresponding model significantly reduces the screening performed by and work load of ophthalmologists. In the future, better predictors and models may increase the number of patients with a safe prediction, further economizing time and healthcare budgets in glaucoma screening. Full article

Background: Visual impairment (VI) continues to be a significant global public health concern, especially in underserved rural communities. Objectives: This study aims to assess the prevalence of VI and refractive errors, as well as to identify the causes and risk factors associated with VI in Duhknah, a rural area in Qassim Province, Saudi Arabia. Methods: This cross-sectional study, conducted in May 2024, included 929 participants aged 6–90 years from Duhknah, a rural area in Qassim Province, Saudi Arabia. Refractive errors (REs) were measured using a non-cycloplegic autorefractometer. Anterior and posterior eye examinations were performed using slit lamp biomicroscopy, direct ophthalmoscopy, and 90 D fundus biomicroscopy. VI was classified based on the International Classification of Diseases 11th revision (ICD-11), 2018. Results: The findings revealed that 671 (72.2%) participants had never undergone an eye examination. The overall prevalence of presenting VI was 370 (39.8%), comprising 21.6% with mild VI, 11.0% moderate, 4.1% severe, and 3.1% classified as blind. The prevalence of hyperopia, myopia, and astigmatism was 20.6%, 36.9%, and 13.2%, respectively. Uncorrected REs were the most common cause of VI (81.4%), followed by amblyopia (13.5%) and cataracts (3.2%). Regression analysis showed that women had 1.58 times higher odds of VI (p = 0.001). Participants with eye examinations for one year or more had 3.64 times higher odds (p < 0.001). Additionally, the risk of VI was significantly lower among older participants (ages 18–90) compared to younger ones (ages 6–17), (p < 0.001). Conclusions: This study found most participants had never had an eye exam, and VI was highly prevalent in the rural community. These findings underscore the need to strengthen primary eye care in rural Saudi Arabia. Regular vision screening, particularly for children, and better access to refractive services could significantly reduce VI and support the goals of Saudi Vision 2030. Full article

Background/Objectives: Dry eye (DE) can cause persistent eye rubbing, contributing to keratoconus (KC) development and progression. Both keratoconus (KC) and dry eye (DE) significantly impact patients’ functional and emotional well-being, with KC patients exhibiting a higher prevalence of DE symptoms and signs. This study examined whether functional (KEPAQ-F) and emotional (KEPAQ-E) quality of life, assessed by the Keratoconus End-Points Assessment Questionnaire, differ when influenced by symptoms and clinical signs of general DE versus meibomian gland dysfunction (MGD) in KC patients. Methods: Volunteers with KC (ages 18–70) underwent DE and MGD assessments, completing OSDI, MGD (MGDQ), and KEPAQ questionnaires. Clinical measures included NITBUT, Schirmer, and meibography. Pearson correlations and path analysis assessed relationships between DE and MGD symptoms and KEPAQ-F/E. Results: Forty-five KC participants (mean age: 45 ± 13, range: 20–69 years, 25 males) were enrolled; 22 (49%) had DE, and 15 (33%) had MGD. Significant correlations were observed between KEPAQ-E (2.9 ± 3.0 Logit) and KEPAQ-F (1.7 ± 3.0 Logit) scores with OSDI (26.5 ± 26.7) and MGDQ (3.3 ± 2.2) scores, and all Belin outcome measures A-D for all participants. In participants with diagnosed dry eye, KEPAQ E and F were also significantly correlated with loss of meibomian glands in the lower eyelids (R = −0.44, p = 0.04). Path analysis showed both DE and MGD were negatively correlated with lower KEPAQ-E and KEPAQ-F scores, with DE symptoms more influential (p < 0.05). The model explained 42% of the KEPAQ-E variance and 41% of the KEPAQ-F variance. Conclusions: Emotional and functional quality of life in KC is significantly and negatively related to DE and MGD symptoms, with DE symptoms exhibiting a greater impact. Furthermore, greater loss of meibomian glands in the lower eyelids is significantly associated with reduced emotional and functional KEPAQ scores in DE patients. These results underscore the critical importance of evaluating DE in KC to improve patient-reported outcomes. Full article

Background: Choroidal nevi are common, benign tumors. These tumors rarely cause adverse retinal sequalae, but when they do, they can lead to disruption of the outer retina and vision loss. In this paper, we used high-resolution retinal imaging modalities, optical coherence tomography (OCT) and adaptive optics scanning laser ophthalmoscopy (AOSLO), to longitudinally monitor retinal sequelae of a submacular choroidal nevus. Methods: A 31-year-old female with a high-risk choroidal nevus resulting in subretinal fluid (SRF) and a 30-year-old control subject were longitudinally imaged with AOSLO and OCT in this study over 18 and 22 months. Regions of interest (ROI) including the macular region (where SRF was present) and the site of laser photocoagulation were imaged repeatedly over time. The depth of SRF in a discrete ROI was quantified with OCT and AOSLO images were assessed for visualization of photoreceptors and retinal pigmented epithelium (RPE). Cell-like structures that infiltrated the site of laser photocoagulation were measured and their count was assessed over time. In the control subject, images were assessed for RPE visualization and the presence and stability of cell-like structures. Results: We demonstrate that AOSLO can be used to assess cellular-level changes at small ROIs in the retina over time. We show the response of the retina to SRF and laser photocoagulation. We demonstrate that the RPE can be visualized when SRF is present, which does not appear to depend on the height of retinal elevation. We also demonstrate that cell-like structures, presumably immune cells, are present within and adjacent to areas of SRF on both OCT and AOSLO, and that similar cell-like structures infiltrate areas of retinal laser photocoagulation. Conclusions: Our study demonstrates that dynamic, cellular-level retinal responses to SRF and laser photocoagulation can be monitored over time with AOSLO in living humans. Many retinal conditions exhibit similar retinal findings and laser photocoagulation is also indicated in numerous retinal conditions. AOSLO imaging may provide future opportunities to better understand the clinical implications of such responses in vivo. Full article

Objectives: To compare the objective refraction of young hyperopes obtained by two wavefront autorefractors with identical measurement principles but different optical designs: a monocular closed-field (VX 120) and a binocular open-field (Eye Refract), both developed by the same manufacturer (Visionix; Pont-de-l’Arche, France). Methods: A randomized, cross-sectional study was carried out with 37 hyperopic participants (18.2 ± 7.8 years; range 8 to 31 years). Each participant underwent two measurement sessions (one with and one without cycloplegia), during which three measurements were taken per autorefractor (monocular and binocular). Refractive variables (M, J0, and J45) were analyzed in one randomly selected eye. Results: The spherical equivalent (M) showed significant differences between autorefractors under noncycloplegic and cycloplegic conditions (p < 0.001). Without cycloplegia, the binocular autorefractor measured +0.45 (+1.49, −0.58) D more hyperopia than the monocular device. Under cycloplegia, this difference decreased to +0.26 D (+0.99, −0.48) D. Both autorefractors provided higher hyperopia with cycloplegia, with differences inversely correlated with age (r = −0.4; p < 0.05). Conclusions: Whenever possible, refraction in young hyperopes should be measured under cycloplegic conditions using a binocular open-field autorefractor to promote greater accommodative relaxation and ensure more reliable hyperopia measurements in both clinical practice and research. Full article

Background/Objectives: Genetic testing is important for diagnosing inherited retinal diseases (IRDs), but further evidence is needed on the utility of singleton genetic testing in an Australian cohort. Methods: A consecutive series of individuals with clinically diagnosed IRDs without prior genetic testing underwent commercial panel-based sequencing (Invitae or Blueprint Genetics), clinical assessment, and multimodal imaging. Retinal images were graded using the Human Phenotype Ontology terms. Binary logistic regression was used to evaluate clinical predictors of a positive molecular diagnosis. Results: Among 140 participants (mean age 49 ± 19 years), genetic testing was undertaken, on average, 23 ± 17 years after the initial clinical IRD diagnosis. Of the 60% who received a probable molecular diagnosis, 40% require further phase testing, highlighting the limitations of singleton genetic testing. USH2A, ABCA4, and RPGR were the most common encountered genes; 67% of the probably solved participants had causative genes with targeted experimental treatments in ongoing human clinical trials. Symptom onset before the age of 30 (OR = 3.06 [95% CI: 1.34–7.18]) and a positive IRD family history (OR = 2.87 [95% CI: 1.27–6.78]) were each associated with higher odds of receiving a molecular diagnosis. Diagnostic rates were comparable across retinal imaging phenotypes (atrophy and autofluorescence patterns in widespread IRD, and the extent of dystrophy in macular IRDs). Conclusions: In an Australian IRD population without prior genetic testing, commercial panels yielded higher diagnostic rates in individuals with IRD onset before the age of 30 and those with an IRD family history. Further research is needed to understand the genetic basis of IRDs, especially isolated and late-onset cases, to improve diagnosis and access to emerging therapies. Full article

Background and Objectives: To clinically validate a semi-automatic measurement of Tear Meniscus Central Area (TMCA) to differentiate between Non-Aqueous Deficient Dry Eye (Non-ADDE) and Aqueous Deficient Dry Eye (ADDE) patients. Materials and Methods: 120 volunteer participants were included in the study. Following TFOS DEWS II diagnostic criteria, a battery of tests was conducted for dry eye diagnosis: Ocular Surface Disease Index questionnaire, tear film osmolarity, tear film break-up time, and corneal staining. Additionally, lower tear meniscus videos were captured with Tearscope illumination and, separately, with fluorescein using slit-lamp blue light and a yellow filter. Tear meniscus height was measured from Tearscope videos to differentiate Non-ADDE from ADDE participants, while TMCA was obtained from fluorescein videos. Both parameters were analyzed using the open-source software NIH ImageJ. Results: Receiver Operating Characteristics analysis showed that semi-automatic TMCA evaluation had significant diagnostic capability to differentiate between Non-ADDE and ADDE participants, with an optimal cut-off value to differentiate between the two groups of 54.62 mm² (Area Under the Curve = 0.714 ± 0.051, p < 0.001; specificity: 71.7%; sensitivity: 68.9%). Conclusions: The semi-automatic TMCA evaluation showed preliminary valuable results as a diagnostic tool for distinguishing between ADDE and Non-ADDE individuals. Full article

In this study, we address the question of whether a waveguide with absorbing sidewalls can be considered pseudo free space and if the free-space transfer function is valid in such a medium. We test this hypothesis by applying a phase retrieval algorithm based on the free-space transfer function. First, optical measurements are carried out to measure the optical properties of a stack of thin films and select the parameters of simulations. Next, the propagation of light in a waveguide was simulated in COMSOL, and the phase of a wave was retrieved in MATLAB. Analysis was performed both for free-space conditions, and for a waveguide with absorbing sidewalls. The cross-correlation between the distributions of intensity under both conditions was about 0.40. The RMS error of the wave retrieved under free-space conditions was 0.378 rad, while that in the case of absorbing sidewalls was 0.323 rad, indicating successful retrieval. The successfully recovered phase of the input wave suggests that a waveguide with absorbing sidewalls can be approximated as pseudo free space and the free-space transfer function may be valid. These results may be used in future studies on how to shorten the phase retrieval of two-dimensional objects. Full article

This study employs a machine learning approach to identify a small-molecule-based signature capable of predicting Alzheimer’s disease (AD). Utilizing metabolomics data from the plasma of a well-characterized cohort of 94 AD patients and 62 healthy controls; metabolite levels were assessed using the Biocrates MxP^® Quant 500 platform. Data preprocessing involved removing low-quality samples, selecting relevant biochemical groups, and normalizing metabolite data based on demographic variables such as age, sex, and fasting time. Linear regression models were used to identify concomitant parameters that consisted of the data for a given metabolite within each of the biochemical families that were considered. Detection of these “concomitant” metabolites facilitates normalization and allows sample comparison. Residual analysis revealed distinct metabolite profiles between AD patients and controls across groups, such as amino acid-related compounds, bile acids, biogenic amines, indoles, carboxylic acids, and fatty acids. Correlation heatmaps illustrated significant interdependencies, highlighting specific molecules like carnosine, 5-aminovaleric acid (5-AVA), cholic acid (CA), and indoxyl sulfate (Ind-SO₄) as promising indicators. Linear Discriminant Analysis (LDA), validated using Leave-One-Out Cross-Validation, demonstrated that combinations of four or five molecules could classify AD with accuracy exceeding 75%, sensitivity up to 80%, and specificity around 79%. Notably, optimal combinations integrated metabolites with both a tendency to increase and a tendency to decrease in AD. A multivariate strategy consistently identified included 5-AVA, carnosine, CA, and hypoxanthine as having predictive potential. Overall, this study supports the utility of combining data of plasma small molecules as predictors for AD, offering a novel diagnostic tool and paving the way for advancements in personalized medicine. Full article