Medical hypothesis, discovery & innovation in optometry

Background: Anisometropia is associated with asymmetric ocular growth and may influence retinal structure, yet its impact on retinal nerve fiber layer thickness (RNFLT) remains incompletely understood. RNFLT is influenced by axial length (AL) and refractive status, and anisometropia is frequently associated with amblyopia. This study aimed to evaluate RNFLT and central macular thickness (CMT) in children with anisometropia and to examine their relationships with refractive error and ocular biometric parameters.
Methods: This cross-sectional study included children aged 5–16 years with anisometropia and was conducted at Port Said Ophthalmology Hospital, Egypt, between January and June 2025. Children were eligible if they showed an interocular difference in spherical equivalent refraction (SER) greater than 2.0 diopters. Comprehensive ophthalmic evaluation included visual acuity assessment, cycloplegic refraction, intraocular pressure (IOP) measurement, ocular biometry, and spectral-domain optical coherence tomography. Peripapillary RNFLT and CMT were measured and compared descriptively between worse and fellow eyes and according to amblyopia status. RNFLT was assessed across the superior, nasal, inferior, and temporal quadrants. Correlations between SER and AL, IOP, CMT, and RNFLT were summarized using Spearman’s rank correlation coefficients.
Results: Among 46 children (median age 14 years; range, 5–16 years), 45.7% (n = 21) had anisometropic amblyopia. Compound anisometropia was observed in 42 children (91.3%), mixed anisometropia in three (6.5%), and simple anisometropia in one (2.2%). Nasal RNFLT was numerically greater in worse eyes compared with fellow eyes (median, 84.0 versus 78.0 µm), while the remaining quadrants and CMT showed relatively small interocular differences. RNFLT values were numerically higher in amblyopic eyes than in non-amblyopic eyes across all quadrants, whereas CMT values were similar between the two groups. SER showed a strong negative correlation with AL (r = -0.91) and positive correlations with inferior (r = +0.56), superior (r = +0.67), temporal (r = +0.59), and nasal (r = +0.37) RNFLT. Correlations with CMT (r = -0.22) and IOP (r = +0.19) were weak.
Conclusions: Children with anisometropia showed regional differences in RNFLT, particularly involving the nasal quadrant, while macular thickness remained largely similar between comparison groups. The observed associations between refractive error, AL, and RNFLT suggest a relationship between refractive status and retinal structure. Given the exploratory nature of the comparisons, these findings warrant cautious, primarily descriptive interpretation. Longitudinal studies are warranted to clarify the temporal relationship and clinical relevance of these localized differences.

Background: The chi-squared (X²) test is a fundamental non-parametric statistical method. It is widely employed in clinical, epidemiological, and biomedical research, including ophthalmology and optometry. It is useful for testing hypotheses regarding independence between categorical variables and for assessing the goodness-of-fit of observed categorical frequencies to a specified expected distribution. In this review, we present a thorough examination of the statistical principles and clinical relevance of the X² test, focusing on its application in vision science and related research domains.
Methods: We outline the conceptual framework and methodological steps for conducting the X² test, emphasizing two common applications considered in this review: the goodness-of-fit test and the test of independence. We discuss key assumptions, such as the independence of observations, use of frequency data, and minimum expected cell counts in detail. Moreover, we explain the process of calculating degrees of freedom (df) and interpreting results based on critical values from the X² distribution. Additionally, appropriate measures of effect size, i.e., Phi for 2 × 2 tables and Cramer’s V for larger tables, for assessing association strength, are introduced. To contextualize its clinical relevance, we present four examples from ophthalmology and optometry.
Results: In the first example, the association between vision impairment (VI) category and sex was examined using a 6 × 2 contingency table. Using unrounded expected frequencies, the Pearson X² statistic was 5.31 with 5 df; however, two expected cell frequencies were < 1, indicating that an exact procedure is preferable for formal inference. Cramer’s V was 0.097, indicating a negligible association. The second example examined the association between age category and first-year persistence with antiglaucoma therapy. Here, X² = 6.18 (df = 2, P = 0.045), indicating a statistically significant association, although Cramer’s V was negligible (0.054). In the third example, a 2 × 2 table was used to examine the association between sex and the type of anti-vascular endothelial growth factor injection (aflibercept or ranibizumab). This yielded X² = 0.027 (df = 1, P = 0.870) and Phi = 0.017, indicating no statistically significant evidence of association and a negligible effect. In the goodness-of-fit example, the observed contact-lens distribution differed statistically from the pooled historical reference proportions used in the analysis (X² = 3.99, df = 1, P = 0.046).
Conclusions: The X² test is a widely used tool for analyzing categorical data, enabling clinicians and researchers to assess potential associations between variables. However, its reliability depends on its proper application, including verification of assumptions and appropriate interpretation of effect sizes, along with consideration of statistical significance. In clinical disciplines, such as ophthalmology or optometry, understanding and utilizing the X² test enhances research rigor and the validity of research findings, facilitating better-informed decisions in patient care and in program development.

Background: Contact lens wear is widely preferred for refractive error correction because of its cosmetic appeal and visual benefits. However, safe use requires adherence to proper prescription, wear, and maintenance practices. Non-compliance increases the risk of complications, particularly when contact lenses are procured from non-conventional sources. Despite contact lens wear being a major risk factor for microbial keratitis, data on contact lens procurement and wear habits in Oman remain limited.
Methods: This descriptive cross-sectional study employed non-probability sampling using a self-administered questionnaire conducted between January and April 2024. Participants were 18 years or older, resided in Oman, and reported contact lens use. The survey assessed contact lens procurement, wear patterns, care practices, and compliance with recommended lens care behaviors.
Results: A total of 526 individuals participated, with a mean (standard deviation) age of 23.7 (6.1) years (range: 18–53), representing all governorates of Oman. The majority were female (n = 484, 92.0%) and students (n = 336, 64.0%). Nearly half of participants (n = 259, 49.2%) used contact lenses for cosmetic purposes. While 68.4% (n = 360) wore soft contact lenses, 24.9% (n = 131) were unaware of the type of lenses they used. Approximately 60% (n = 316) of participants did not undergo an eye examination prior to obtaining their first pair of contact lenses; 22.2% (n = 117) purchased lenses online, and 16.2% (n = 85) from pharmacies or beauty salons without specialist consultation. Furthermore, 68.1% (n = 358) did not have regular eye examinations and 18.4% (n = 97) reported sharing contact lenses with friends.
Conclusions: Contact lens use is common among young people in Oman, predominantly for cosmetic purposes, and unsafe practices are widespread. Non-conventional procurement, lack of eye examinations, missed follow-up visits, and contact lens sharing were frequently reported. These findings underscore the need for stricter regulation of contact lens distribution and targeted public health education to promote safe contact lens wear. Future research should use nationally representative samples to further evaluate contact lens safety practices in Oman.

Background: Pediatric ocular trauma is a leading cause of preventable visual morbidity and monocular blindness worldwide. The epidemiology and clinical patterns of ocular injuries vary across regions due to differences in environmental exposure, socioeconomic factors, and supervision practices. Understanding local injury patterns is essential to informing targeted prevention strategies and optimizing clinical management.
Methods: A cross-sectional observational study was conducted at Biratnagar Eye Hospital, a tertiary eye care center in Eastern Nepal, between April and September 2023. Pediatric patients younger than 16 years with ocular trauma were enrolled through hospital presentation and school-based recruitment. Patients with previous ocular trauma, repeat visits for the same injury, follow-up cases, and non-traumatic ocular conditions were excluded. Data on demographic characteristics, educational status, causative agents, place of injury, clinical diagnosis, and management approach were collected at the time of clinical evaluation using a structured proforma. Management was classified as medical, surgical, or observational. Results were summarized using descriptive statistics.
Results: A total of 260 children were included, 184 (70.8%) of whom were male. The highest proportion of ocular trauma was observed in children aged 6–10 years (n = 115, 44.2%). Stick- or wood-related injuries were the most common cause (n = 85, 32.7%), followed by injuries from iron or other sharp objects (n = 45, 17.3%). The majority of injuries occurred at home (n = 170, 65.4%). Open globe injury was the most frequently reported diagnosis category (n = 101, 38.8%). Medical management was used in 57.7% (n = 150) of patients, whereas 40.0% (n = 104) underwent surgical intervention. Observation alone was used in 2.3% (n = 6) of patients.
Conclusions: In this study, pediatric ocular trauma predominantly affected school-aged boys and most commonly occurred in the home environment, often involving largely preventable causes. The substantial burden of open globe injuries highlights the need for strengthened injury prevention strategies, enhanced parental supervision, and timely access to specialized ophthalmic care. Targeted community education and coordinated trauma management approaches may help reduce the incidence and visual consequences of pediatric ocular injuries.

Background: Near point of convergence (NPC) is a key clinical measure used in the assessment of binocular vision function and the diagnosis of convergence insufficiency. Normative NPC values vary across populations and are influenced by demographic and methodological factors. However, published normative NPC data in Oman remain limited. This study aimed to describe normative NPC break and recovery values among university students at the University of Buraimi, Oman, and to examine variations by sex and age.
Methods: This prospective cross-sectional study was conducted among students at the University of Buraimi, Oman. Participants aged 17–25 years with best-corrected distance visual acuity of 20/20 or better, near visual acuity N6, and a Convergence Insufficiency Symptom Survey (CISS) score less than or equal to 21 were included. NPC break and recovery points were measured subjectively using a Royal Air Force (RAF) ruler-based method with an accommodative target. Three consecutive measurements were obtained for each parameter, and mean values were recorded. Descriptive statistics were calculated, and NPC values were summarized by sex and age group.
Results: A total of 350 participants (74.9% female) met the inclusion criteria, with a mean (standard deviation [SD]) age of 20.16 (1.78) years. The overall mean (SD) NPC break point was 10.0 (2.6) cm (95% confidence interval [CI]: 9.7–10.3 cm) and the mean (SD) recovery point was 12.0 (2.0) cm (95% CI: 11.8–12.2 cm). Mean (SD) CISS score was 11.3 (6.3) (95% CI: 10.6–11.9) in this CISS-selected cohort. Females had slightly more remote mean NPC break and recovery points than males (break: 10.2 vs. 9.4 cm; recovery: 12.2 vs. 11.5 cm). Mean NPC break and recovery values were broadly similar across the examined age groups (17–19, 20–22, and 23–25 years).
Conclusions: This study provides descriptive normative NPC break and recovery values for students aged 17–25 years at the University of Buraimi using an RAF ruler-based method. These findings provide local descriptive data that may inform interpretation of NPC measurements in similar populations; however, the reported values should not be interpreted as individual clinical reference limits.

Background: Coronavirus disease (COVID-19) infection can be associated with post-recovery sight-threatening complications like optic neuritis, retinal vascular occlusions, endophthalmitis, and panophthalmitis. This study was conducted to explore the various sight-threatening post-COVID-19 ophthalmic manifestations.
Methods: This retrospective observational case series included seven patients who were diagnosed with sight-threatening manifestations post-COVID-19. They underwent detailed ophthalmic and systemic evaluation, including laboratory investigations for systemic hypercoagulable and inflammatory markers.
Results: Seven Indian patients (6 males:1 female, age range 37–66 years) presented to us with severe eye pain, acute loss of vision, redness, and watering after being diagnosed and treated for COVID-19 infection. The time from COVID-19 diagnosis to ocular sampling was 14–60 days (median 27), that of ocular symptoms to ocular sampling 1–50 days (median 4). Visual acuity ranged from no perception of light to 20/36. Three patients were pre-existing diabetics, two developed diabetes during their COVID-19 treatment. Diagnosis included one case of central retinal artery occlusion, one case of vitreous hemorrhage with retinal vasculitis, two cases of presumed bacterial endogenous endophthalmitis, one case of presumed fungal endophthalmitis, and two cases of panophthalmitis, one of them bilateral. Patients with infective intraocular inflammation were subjected to blood, ocular specimens, and urine cultures, which yielded growth in some patients. PCR of ocular specimens were positive for panfungal and/or eubacterial genome. Treatment included oral and systemic antimicrobial therapy with or without systemic steroids, with intravitreal antibiotics and/or steroids in selected cases. Final visual outcome ranged from no perception of light to 20/20.
Conclusions: Patients in this group had both vascular occlusions and infection as a cause of sight-threatening visual loss. Functional visual outcome may not be achieved in this diverse group of patients. Multi-specialty management was required in most of the cases. Larger prospective studies with controls are required to clarify pathogenesis, optimal screening, and management strategies for post-COVID-19 ocular complications.