Laser-Assisted In Situ Keratomileusis (LASIK) Enhancement for Residual Refractive Error after Primary LASIK

Background: To evaluate the safety, efficacy, and predictability of laser-assisted in situ keratomileusis (LASIK) enhancement after primary LASIK and compare to Food and Drug Administration (FDA) criteria. Methods: Patients who underwent LASIK enhancement after primary LASIK between 2002 and 2019 were compared to those who underwent LASIK without retreatment. Patient demographics, preoperative characteristics, visual outcomes, and postoperative complications were compared between groups. Epithelial ingrowth (EI) development was stratified based on duration between primary and secondary procedures. Results: We compared 901 eyes with LASIK enhancement to 1127 eyes without retreatment. Age, sex, surgical eye, sphere, cylinder, and spherical equivalent (SE) were significantly different between groups (p < 0.05). At 12 months post-enhancement, 86% of the eyes had an uncorrected distance visual acuity of 20/20 or better and 93% of eyes were within ±0.50 D of the target. Development of EI (6.1%) demonstrated an odds ratio of 16.3 in the long-term compared to the short-term (95% CI: 5.9 to 45.18; p < 0.0001). Conclusions: Older age at primary LASIK, female sex, right eye, and larger sphere, cylinder and SE were risk factors for enhancement. Risk of EI significantly increased when duration between primary and enhancement procedures exceeded five years. LASIK enhancements produce favorable outcomes and meet FDA benchmarks for safety, efficacy, and predictability.

Current concepts in the management of childhood myopia

Myopia or short-sightedness is an emerging pandemic affecting more than 50% population in South-Asian countries. It is associated with several sight-threatening complications, such as retinal detachment and choroidal neovascularization, leading to an increased burden of visual impairment and blindness. The pathophysiology of myopia involves a complex interplay of numerous environmental and genetic factors leading to progressive axial elongation. Environmental factors such as decreased outdoor activity, reduced exposure to ambient light, strenuous near work, and role of family history of myopia have been implicated with increased prevalence of this refractive error. While multiple clinical trials have been undertaken to devise appropriate treatment strategies and target the modifiable risk factors, there is no single treatment modality with ideal results; therefore, formulating a comprehensive approach is required to control the myopia epidemic. This review article summarizes the epidemiology, dynamic concepts of pathophysiology, and evolution of the treatment modalities for myopia such as pharmacological (atropine and other agents) and optical methods (spectacles, contact lenses, and orthokeratology).

Prevalence and Distribution of Refractive Errors Among Members of the U.S. Armed Forces and the U.S. Coast Guard, 2019

During calendar year 2019, the estimated prevalence of myopia, hyperopia, and astigmatism were 17.5%, 2.1%, and 11.2% in the active component of the U.S. Armed Forces and 10.1%, 1.2%, and 6.1% of the U.S. Coast Guard, respectively. The prevalence of spectacle correction in the active component of the U.S. Armed Forces was 24.0%, which included single-vision distance (92.0%), multifocal (eg, bifocal, 6.0%), and single-vision reading (2.0%) spectacles. In comparison, the prevalence of spectacle correction was 14.6% in the U.S. Coast Guard. Additionally, among all U.S. Armed Forces service members who received spectacle correction for distance vision in 2019, service members of the reserve component, military academy cadets, and the National Guard were significantly more myopic (near-sightedness) than the active component or Coast Guard (p<.001). Within the active component, the Air Force was the most myopic and the Marine Corps followed it closely. These 2 military branches were not significantly different from each other (p=.46) but both were significantly more myopic than the Navy or the Army (p<.001). The Navy was more myopic than the Army (p=.01). The U.S. Coast Guard was significantly less myopic than any other military branch (p=.03).

Refractive Characteristics and Related Factors of Amblyopia after Lamellar Keratoscleroplasty in Children with Limbal Dermoids

We examined the refractive characteristics and related factors of amblyopia in pediatric patients with limbal dermoids undergoing lamellar keratoscleroplasty. Forty-one children (mean age: 56.15 ± 22.47 months) were enrolled. Cycloplegic refraction, corneal topography, and anterior segment photography were performed. The corneal topographic and distribution characteristics of the refractive state were summarized, and the relationship between limbal dermoid invasion size and the refractive state was analyzed. The relationship between invasion size and amblyopia severity and the effect of clinical intervention at different times on amblyopia treatment were also analyzed. The spherical power distribution was −1.0−+10.75 D (average: +4.79 ± 3.09 D). The cylinder power was −1.25−−8.75 D (average: −4.19 ± 1.93 D). The axial range of astigmatism was 10−180° (average: 103.54 ± 58.16°). Equivalent spherical refraction was −3.88−+7.76 D (average: +2.70 ± 3.08 D). Twenty-five, fifteen, and one case had limboid dermoid invasion of the central circular zone (CCZ), paracentral annular zone (PCZ), and corneal limbus within 1 mm, respectively. Corneal topography of 39 patients showed flat, steep, and mean curvatures of 38.48 ± 2.12 D, 43.29 ± 1.97 D, and 40.70 ± 1.48 D, respectively. The mean astigmatism was 4.80 ± 2.93 D in the 3-mm optical region. Astigmatism was higher in CCZ than in PCZ invasion (p < 0.05). Postoperative visual acuity was positively correlated with patients’ age and amblyopia treatment duration (r = 0.392, p = 0.048; r = 0.488, p = 0.011), and was negatively correlated with astigmatism (r = −0.646, p < 0.001). High hyperopia and astigmatism are the dominant refractive errors in patients with limbal dermoids undergoing lamellar keratoscleroplasty.

Photorefraction with Spot Vision Screener versus Visual Acuity Testing as Community-Based Preschool Vision Screening at the Age of 3.5 Years in Japan

Nationwide in Japan, a community-based vision-screening program in 3.5-year-old children is conducted in three steps: questionnaires and home visual acuity testing as the primary screening; visual acuity testing by nurses and pediatricians’ inspection in community health centers as the secondary screening; and examinations by ophthalmologists as the tertiary screening. In this study, we introduced photorefraction with a Spot vision screener in addition to visual acuity testing to answer the clinical question of whether photorefraction could better detect eye diseases and potentially replace visual acuity testing. Photorefraction was performed on 813 consecutive 3.5-year-old children in a center. The children were sent to tertiary examinations, which were based on the Spot vision screener standard, in addition to the visual acuity testing standard: failure in either eye to pass 0.5 visual acuity in a center. A notice to visit ophthalmologists was issued for 95 children (11%), and documents with the diagnosis were sent back to the Heath Office for 76 children (80%). The rate of children with anisometropic or ametropic amblyopia or accommodative esotropia as treatment-requiring diseases was highest in cases of no pass at both standards (10/15 = 66%), and higher in cases of no pass only at the Spot vision screener standard (13/45 = 28%), compared with cases of no pass only at the visual acuity testing standard (6/33 = 18%, p = 0.0031). Photorefraction, in addition to visual acuity testing and inspection led to additional eye diseases detection at 3.5 years. Visual acuity testing at home would not be omitted in the introduction of photorefraction.

Prevalence of refractive errors in school-going children of Taif region of Saudi Arabia

PURPOSE

To determine the prevalence of refractive errors in the pediatric population in Taif, Saudi Arabia.

METHODS

This cross-sectional study included 7356 eyes of 3678 primary and secondary school children (males = 1837; females = 1841) with a mean age of 11.8 ± 2.2 years (range: 7-18) (males = 11.4 ± 2.0 [range: 8-16]; females = 12.2 ± 2.3 [range: 7-18]). All participants were selected from the school registers. The participants underwent noncycloplegic refraction to determine refractive errors. Students who refused visual acuity assessment or eye examination and were inconsistent in visual acuity assessment were excluded.

RESULTS

The manifest refraction spherical equivalent of the study population was 0.37 ± 1.52 D (range from - 18.4 to 8.8 D) (males = -0.32 ± 1.4 D [range - 15.88-8.8 D]; females = -0.42 ± 1.6 D [range - 18.38-8.0 D]). The overall prevalence of uncorrected refractive errors among school children in this study was 50.91%. The overall distribution of astigmatism (cylinder error of ≥0.50 D) in the current study population was found to be 50.14% (3688/7356 eyes).

CONCLUSION

Nearly half of the study population in this area was affected with at least one type of refractive error. The findings reveal the necessity for implementing timely and sensitive screening programs/methods to identify and correct refractive errors in this age group.

Age-specific influences of refractive error and illuminance on pupil diameter

To assess the most influential factor for pupil diameter changes among age, illuminance, and refractive state and reestablish the optimal procedures for clinical applications based on refractive state and illuminance for different age groups. The study was an observational study (repeated measure study). Participants included 219 Korean adults aged 20 to 69 years. Pupil diameters were measured using a pupilometer under scotopic, mesopic-low, and mesopic-high lighting conditions. Factor interactions among age, illuminance, and refractive state were evaluated using mixed linear model and chi-square automated interaction detection. Illuminance mainly contributed to variations in pupil diameter of participants over 50 years, whereas the refractive state was the dominant controlling factor for the pupil variation in participants below 50 years. For more generalized application, the pupil diameter decreased with older age and brighter illuminance (P < .001, inverse correlation, all comparisons). The mean pupil diameter was significantly higher in myopes and emmetropes than in hyperopes (P < .001). Pupil diameter variation modeled using the mixed model confirmed age, illuminance, and refractive error as significant factors (P < .001). Accounting for the interactions among age, illuminance, and refractive error and establishing their hierarchical dominance can be generalized using the chi-square automated interaction detection method and mixed model. Promoting age-dependent consideration for both illuminance and refractive state is necessary when pupil diameters play significant roles in clinical and manufacturing circumstances.

Childhood Vision Impairment and Refractive Error in Zimbabwe: A Hospital-based Retrospective Study

Background

The objective of this study was to determine the causes and distribution of vision impairment and refractive error among children in Zimbabwe.

Methods

A hospital-based retrospective cross-sectional study was conducted among children (3–16) who attended the Eye Institute, Harare, Zimbabwe, from January 2010 to December 2020. Patients' records were collated, and variables such as visual acuity, ocular morbidities, and vision impairment were analysed.

Results

During this time, 1038 children with mean age of 10.63 ± 3.54 years visited the facility. The majority of them were males (53.2%). Prior to treatment, 9.9% of the children had vision impairment which reduced to 3.5% after intervention. Uncorrected refractive error accounted for the majority of vision impairment (67.0%), followed by keratoconus (7.8%), corneal opacity/ulceration (6.8%), and amblyopia (6.8%), among other conditions. Astigmatism (60.6%) was the most prevalent type of refractive error followed by myopia (37.5%).

Conclusion

The prevalence of childhood vision impairment is higher than that found in similar hospital-based studies conducted in Africa. The most common reason for childhood vision impairment was uncorrected refractive error.

High Prevalence of Astigmatism in Children after School Suspension during the COVID-19 Pandemic Is Associated with Axial Elongation

During the COVID-19 pandemic, the Hong Kong Government enforced a “school from home” policy between February and September 2020. This cross-sectional epidemiological study was conducted to investigate the prevalence of astigmatism and visual habits after the home confinement period. Vision screenings were conducted at three local government-funded primary schools in Hong Kong from October 2020 to December 2020. A total of 418 ethnically Chinese primary school children completed the eye examination and returned questionnaires concerning demographic information and visual habits. It was found that 46.5% (95% CI, 41.7−61.4%) of the children aged 8 to 11 years had astigmatism ≥ 0.75 D, which was predominately With-The-Rule astigmatism. The prevalence of astigmatism reported in these children is generally higher than that of studies conducted before COVID. Compared to their non-astigmatic peers, astigmatic children had a longer axial length (p < 0.001) and engaged in fewer outdoor activities (p = 0.04). Multiple linear regression analyses also revealed significant relationships between axial length and both cylindrical error and J0 astigmatism. Due to the high astigmatism prevalence, there is a pressing need for further studies on the long-term impact of the pandemic on children’s vision.

Visual impairment and refractive errors in school children in Andhra Pradesh, India

Purpose

Addressing childhood vision impairment (VI) is one of the main goals of the World Health Organization's (WHO) combating blindness strategies. The primary aim of this study was to estimate the prevalence of VI, causes, and its risk factors in school children in Krishna district, Andhra Pradesh, India.

Methods

Children aged 4-15 years were screened in schools using the 6/12 Snellen optotype by trained community eye health workers, and those who failed the test and those reported or found to have obvious eye conditions were referred to primary (VC), secondary (SC), or tertiary (TC) care centre appropriately, where they underwent a complete eye examination including cycloplegic refraction and fundus examination.

Results

A total of 56,988 children were screened, of whom 51.18% were boys. The mean age was 9.69 ± 3.26 years (4-15 years). Overall, 2,802/56,988 (4.92%) children were referred to a VC, of which 632/56,988 (1.11%) required referral to SC/TC. PVA of <6/12 was found in 1.72% (95% confidence interval [CI]: 1.61-1.83). The prevalence of refractive error (corrected and uncorrected) was 2.38% (95% CI: 2.26-2.51) and myopia was 2.17% (95% CI: 2.05-2.29). In multivariable analysis, older children, those in urban schools, private schools, and children with a disability had an increased risk of VI and myopia. Additionally, the risk of myopia was higher among girls than boys. Of those referred and reached SC/TC, 73.64% were due to avoidable causes.

Conclusion

Childhood VI prevalence was 1.72% in this region. Uncorrected refractive error (URE) was the major cause of VI in children. Older age, schools in urban locations, private schools, and the presence of disability were associated with the risk of VI among children.

A comparative study of Pentacam indices in various types and severities of refractive error in candidates for photorefractive keratectomy (PRK) surgery

This study aimed to specify Pentacam indices in patients who suffered from different types of refractive error and underwent photorefractive keratectomy (PRK) surgery. It is a descriptive cross-sectional study carried out on 1125 patients (2215 eye samples) who underwent PRK surgery in the Noor Surgical Center of Ardabil, Iran, over a 5 year period (2014-2018). A particular checklist was provided to patients, which consisted of demographic data, pachymetry test, keratometry, refractive error, corneal-thickness indices, and corneal surface area indices. The data were analysed using the statistical analysis package of IBM^® V25. The mean age of the participants in this study was 28.48±6.82 years, and the ratio of women to men was 66.4%. It was observed that the differences between angle, volume, the depth of the anterior chamber, IVA, and ISV were significant (P=0.00) when compared to each other in all types of refractive errors. High myopes had significantly higher K_max front than low myopes (P=0.00). In astigmatism patients, the K_max in front of the cornea in extreme type was significantly higher than in moderate (P=0.00) and high (P=0.01) types. High myopes had significantly lower R_min than mild myopes (P=0.02), and extreme astigmatism had significantly lower R_min than high (P=0.014) and moderate types (P=0.013). The data from this study revealed that in patients undergoing PRK surgery, some Pentacam indices could be related to some types of refractive error, and in some of these indices, there are statistically significant differences between different severities of refractive errors. Therefore, their preoperative evaluation is very important.

Refractive errors, road traffic accidents and long-term spectacle compliance amongst commercial taxi drivers in a major North-East Indian city

Purpose

To assess the prevalence of refractive error (RE) and its association with road traffic accidents (RTAs) and the subsequent long-term spectacle compliance and adherence to suggested appropriate strategies In Shillong, India.

Methods: This

prospective study was conducted between July and October 2019 among commercial taxi drivers (CTDs), with follow-up interviews conducted with a subset of respondents to assess long-term spectacle compliance after a year. Gross ophthalmologic examination was performed, including visual acuity and refraction. Descriptive statistics and Chi-square tests were conducted to assess the association between the type of REs, spectacle compliance, and selected sociodemographic and clinical variables. Multiple logistic regression was performed for analysis of the association between RTAs and sociodemographic, clinical, and work characteristics variables.

Results

A total of 382 (95.5%) CTDs completed interviews and gross eye examination. The prevalence of any RE in the worst eye was 28.8% (95% CI: 24.3-33.6). Presbyopia with or without distance vision was the commonest type of RE with 21.7% (95% CI: 17.7%-26.2). Among those who were prescribed spectacles, 70.5% needed near correction. Drivers with RE were nearly two times (OR: 2.6; 95% CI: 1.4-5.1) more likely to be involved in RTAs compared to those without any RE. Long-term spectacle compliance was at 40.9%. The predominant barrier reported for spectacle compliance was "can manage well without spectacles."

Conclusion

This survey has demonstrated a significant relationship between poor vision and occurrence of RTAs. There is an urgent need for tailor-made targeted interventions to address the eye health needs of CTDs in India.

Refractive errors among commercial drivers

Purpose

To determine the pattern of refractive error among commercial drivers in north India.

Methods

Descriptive study with convenient sampling conducted among commercial drivers of north India.

Results

A total of 213 (75.8%) heavy-vehicle and 68 (24.2%) light-vehicle drivers were screened for eye diseases. Refractive error for distance was reported in 44 (15.7%; 95% CI: 11.6-20.4) drivers. Hyperopia was reported in 23 (8.2%; 95% CI: 5.2-12) drivers, followed by myopia in 15 (5.3%; 95% CI: 3-8.6) drivers and astigmatism in six (2.1%; 95% CI: 0.7-4.5) drivers. Presbyopia was reported in 157 (55.8%) drivers. Dry eye was reported in 70 (24.9%), stereo deficiency in 77 (27.4%), and color vision deficiency in 11 (3.9%) drivers. Three drivers were diagnosed with cataract, and two were referred for retina evaluation.

Conclusion

Hyperopia in both eyes was the most common refractive error. Dry eye disease and color vision deficiency were also reported. Most of the drivers were not using spectacles for refractive error correction. Due to their mobile nature, drivers with cataract and retina diseases did not turn up for follow-up.

Refractive Shifts and Changes in Corneal Curvature Associated With Antibody-Drug Conjugates

PURPOSE

Antibody-drug conjugates (ADCs) are a class of cancer drug wherein some are associated with corneal abnormalities, but there is a dearth of published information on refractive shifts in patients receiving ADCs. Here, we evaluated the dynamics of refractive error and keratometry readings in patients with ADC-related keratopathy and microcyst-like epithelial changes (MECs).

METHODS

This study is a retrospective case series including 58 eyes of 29 patients with ADC-related keratopathy from a single tertiary care cancer referral center (MSKCC). One eye (29 total) was randomly assigned for statistical analysis. In addition, a subset analysis of MEC location-refractive error correlation was performed on 20 eyes. Clinical records including slitlamp examination, indirect ophthalmoscopy, calculated spherical equivalence (SE), keratometry, and visual acuity were recorded at baseline, during, and off treatment.

RESULTS

A subset analysis of MEC location-refractive error correlation of 20 eyes revealed the following: Peripheral MECs were significantly associated with hyperopic shifts (P value < 0.001) and paracentral/central associated with myopic shifts (P value < 0.001). In the full cohort and on drug, the greatest change in SE from baseline was myopic (68%, as high as -4.75 D) and hyperopic (32%, as much as +3.75 D). Eighty-nine percent had a change in vision from baseline while on drug, but at the 3-month follow-up off drug, SE and vision returned to baseline in 33% and 82% of eyes.

CONCLUSIONS

Peripheral MECs were significantly associated with hyperopic shifts, and paracentral/central MECs were associated with myopic shifts. While on drug, most eyes had a myopic refractive shift, which corresponded with corneal steepening.

A systematic review of near work and myopia: measurement, relationships, mechanisms and clinical corollaries

After decades of investigation, the role of near work in myopia remains unresolved, with some studies reporting no relationship and others finding the opposite. This systematic review is intended to summarize classic and recent literature investigating near work and the onset and progression of myopia, potential mechanisms and pertinent clinical recommendations. The impact of electronic device use is considered. PubMed and Medline were used to find peer-reviewed cross-sectional and longitudinal studies related to near work and myopia from 1980 to July 2020 using the PRISMA checklist. Studies were chosen using the Joanna Briggs Institute checklist, with a focus on studies with a sample size greater than 50. Studies were independently evaluated; conclusions were drawn per these evaluations. Numerous cross-sectional studies found increased odds ratio of myopia with increased near work. While early longitudinal studies failed to find this relationship, more recent longitudinal studies have found a relationship between myopia and near work. Rather than daily duration of near work, interest has increased regarding absolute working distance and duration of continuous near viewing. Several reports have found that shorter working distances (<30 cm) and continuous near-work activity (>30 min) are risk factors for myopia onset and progression. Novel objective continuously measuring rangefinding devices have been developed to better address these questions. The literature is conflicting, likely due to the subjective and variable nature in which near work has been quantified and a paucity of longitudinal studies. We conclude that more precise objective measures of near viewing behaviour are necessary to make definitive conclusions regarding the relationship between myopia and near work. Focus should shift to utilizing objective and continuously measuring instruments to quantify near-work behaviours in children, followed longitudinally, to understand the complex factors related to near work. A better understanding of the roles of absolute working distance, temporal properties, viewing breaks and electronic device use on myopia development and progression will aid in the development of evidence-based clinical recommendations for behavioural modifications to prevent and slow myopia.

Ocular biometry characteristics and its relationship with age, gender, spherical equivalent in Turkish children

Background

Studying ocular biometric parameters in different populations and determining the relationship with personal characteristics can provide valuable information about ocular growth and help provide a better understanding of refractive errors.

Aims

To describe distributions of ocular biometry and to evaluate its associations with age, gender, spheric equivalent in Turkish children.

Patients and Methods

In this prospective study 344 children aged 3-14 years were evaluated. Parameters studied included axial length (AL), anterior chamber depth (ACD), and mean corneal radius (CR) measured with optical biometry. Cycloplegic refraction values were obtained using autorefractometer. The change of biometric parameters according to age and gender were evaluated. The relationship between ocular biometry parameters with refraction and age was analyzed by linear regression.

Results

Mean spherical equivalent (SE), AL, ACD and AL/CR observed to be lowest in the preschooler group (P < 0.001). SE reduced with age, and a weak correlation observed between SE and age (r = -0.333). AL and ACD had moderate and weak positive correlations with age respectively (r = 0.511; r = 0.304). There were negative correlations between SE with AL, ACD and AL/CR (r = -0.826; r = -0.540; r = -0.886). The strongest correlation with SE among these parameters was identified for AL/CR. AL and ACD were higher in boys, while the CR was lower in girls (p < 0.001).

Conclusion

While AL in children in late schooler group is higher than European countries, it shows similar characteristics in early schooler group. In addition AL is lower in all age groups than Asian population sexcept preschooler group. With age AL increases, SE decreases and AL plays a key role in refractive development.

Alteration in pattern reversal visual evoked potential in pediatric population with amblyopia and spherical refractive errors

Purpose

To study the effect of refractive errors on pattern visual evoked potential (VEP) recordings in the pediatric population.

Methods

This cross-sectional observational study assessed 240 eyes of 120 participants attending the outpatient department of a tertiary care center in North India. Participants were between 8 and 18 years of age; 30 participants each were recruited into four groups, namely emmetropia, myopia, hypermetropia, and amblyopia. They were then subjected to pattern reversal VEP, with P-100 amplitude and latency recorded for each participant.

Results

The emmetropic group in this study provided normal values of P-100 parameters, namely P-100 latency and P-100 amplitude with readings of 115.78 ± 10.19 ms and 11.11 ± 4.08 μV, respectively. P-100 amplitude was significant compared to P-100 latency in detecting the presence or absence of a specific type of refractive error. It was found that there was a significant association between severity of myopia and P-100 latency (both unaided and aided) with P < 0.05. The severity of hypermetropia showed a significant association with P-100 amplitude (unaided) (P < 0.05). Receiver operating characteristics analysis revealed P-100 amplitude to be a good predictor of refractive error and the cut-offs were calculated.

Conclusion

The P-100 parameters of the pediatric Indian population were comparatively higher than conventional values. P-100 latency seemed to better correlate with myopia, while hypermetropia correlated with P-100 amplitude. P-100 amplitude appears to be the most significant predictor of the presence of refractive error in an individual.

Chinese Version of the Vision-Related Quality of Life (NEI-VFQ-25) among Patients with Various Ocular Disorders: A Pilot Study

Background and Objectives: Subjective visual function is currently becoming an increasing appreciation in assessing the health-related quality of life. This study aimed to assess the vision-related quality of life (VRQOL) among patients with refractive errors, keratoconus, senile cataract, and age-related macular degeneration (AMD) using the Chinese version of the National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ-25). Materials and Methods: The questionnaire of NEI-VFQ-25 was filled out in a clinical setting or by telephone/mail. Univariate and multivariate analyses were used to determine which factors are associated with the NEI-VFQ-25. Results: From June 2018 to January 2019, 28 patients with refractive error, 20 patients with keratoconus, 61 with senile cataracts, and 17 with AMD completed the questionnaire NEI-VFQ-25. There were significant differences in the NEI-VFQ-25 subscale of general vision (p = 0.0017), ocular pain (p = 0.0156), near activities (p = 0.0002), vision-specific social functioning (p = 0.007), vision-specific mental health (p = 0.0083), vision-specific dependency (p = 0.0049), color vision (p < 0.0001), peripheral vision (p = 0.0065), and total score (p < 0.0001) among four disease groups, respectively. The multiple linear regression revealed that the best-corrected visual acuity (BCVA) and disease group were important factors of the total NEI-VFQ-25. After adjusting for BCVA, patients with AMD had a worse total NEI-VFQ-25 score than patients with refractive error, keratoconus, or senile cataracts. Conclusions: Among the patients with four ocular disorders and a broad vision spectrum from normal, partial sight, low vision to legal blindness, the BCVA of their better eye was the most important factor in the VRQOL.

Refractive Outcomes of Non-Toric and Toric Intraocular Lenses in Mild, Moderate and Advanced Keratoconus: A Systematic Review and Meta-Analysis

Background: To perform a systematic review and meta-analysis of the refractive outcomes of non-toric and toric intraocular lenses (IOLs) in keratoconus (KC) using different IOL power calculation formulas. Methods: A systematic search was conducted to identify studies that report on refractive outcomes of different IOL power calculation formulas in KC patients undergoing cataract surgery. Inclusion criteria were primary posterior chamber non-toric and toric monofocal intraocular lens implantation, data on the degree of KC, explicit mention of the formula used for each stage of KC, and the number of eyes in each category. We calculated and compared the absolute and mean prediction errors, percentage of eyes within 0.5 D and 1 D from target, and the weighted absolute prediction errors of IOL formulas, all were given for KC degrees I–III. Results: The bibliographic search yielded 582 studies published between 1996 and 2020, 14 of which (in total 456 eyes) met the criteria: three studies on non-toric IOL (98 eyes), eight studies on toric IOLs (98 eyes) and three studies of unknown separation between non-toric and toric IOLs (260 eyes). The lowest absolute prediction error (APE) for mild, moderate, and advanced KC was seen with Kane’s IOL power formula with keratoconus adjustment. The APE for the top five IOL power formulas ranged 0.49–0.73 diopters (D) for mild (83–94%) of eyes within 1 D from the target), 1.08–1.21 D for moderate (51–57% within 1 D), and 1.44–2.86 D for advanced KC (12–48% within 1 D). Conclusions: Cataract surgery in eyes with mild-to-moderate KC generally achieves satisfactory postoperative refractive results. In patients with advanced KC, a minority of the eyes achieved spherical equivalent refraction within 1 D from the target. The Kane’s formula with keratoconus adjustment showed the best results in all KC stages.

Uncorrected refractive error in a university community

Aims and Background

To determine the prevalence and pattern of uncorrected refractive error among staff of a Nigerian university.

Patient and Methods

A cross-sectional study of consecutive staff of the University of Nigeria, Nsukka, Nigeria who presented for a 10-day free eye screening program. Demographic data and data on eye care awareness and knowledge were obtained with a combination of self-administered and interviewer-administered questionnaires in the English language. Clinical examinations included visual acuity taken at 6 m with Snellen's chart; noncontact tonometry; pen-torch eye examination; and direct ophthalmoscopy; autorefraction and subjective refraction.

Results

One thousand and eighty-three subjects aged 18-82 years (mean = 44.1 ± 12.15 years) comprising 568 females (52.4%) and 515 males (47.6%) were screened. Eighty-nine subjects (8.3%) were visually impaired and five subjects (0.5%) were blind. Three hundred and fifty-six subjects were diagnosed with refractive error (356/1083; 32.9%), out of which 149 subjects (41.9%) were uncorrected. The prevalence of uncorrected refractive error in this study population was 13.8%. Astigmatism was the commonest refractive error, whereas hypermetropia and hypermetropic astigmatism were the commonest spherical and astigmatic errors, respectively.

Conclusion

A significant proportion of the staff of this Nigerian university still lives with uncorrected refractive error with its attendant consequences. Regular eye checks should be done by the staff of our universities and effort should be intensified in eye care awareness creation among the populace, including the apparently enlightened communities.

Prevalence and determinants of refractive error and related ocular morbidities among Saudi adolescence population in Riyadh, Saudi Arabia

PURPOSE

The purpose of this study was to determine the magnitude and determinants of refractive error (RE) and related ocular morbidities among preparatory and secondary Saudi students in Riyadh.

METHODS

This study was conducted in 2017-2018 at preparatory (12-14 years) and secondary (15-18 years) schools. A "Spot Screener" was used to determine if the child passed or failed a refraction test. Fail test meant RE ≥ ± 0.50 D. Data were collected on refractive status in each eye, anisometropia, and strabismus. The type of RE was estimated and analysis was performed for an association to gender, age, and education levels. The use of spectacle while screening defined the compliance of spectacle wear.

RESULTS

The study sample was comprised of 708 Saudi students. There were 59.5% of boys. The prevalence of RE was 43.6% (95% confidence interval [CI]: 40.0, 47.3). The prevalence of RE in preparatory and secondary students was 44.5% and 43.2%, respectively. The proportion of myopia (≥ -0.5 D) and hyperopia (≥ +0.5 D) among students with RE was 82.2% and 17.8%, respectively. Family history of RE was positively associated to RE in students (odds ratio: 1.8 [95% CI: 1.3, 2.5]). The current screening initiative identified 45 (6.4%) new cases of RE who required spectacles. The compliance rate for using visual aid among students with RE was 74.6%. The prevalence of anisometropia and strabismus was 3.0% and 4.1%, respectively.

CONCLUSIONS

A high proportion of Saudi adolescence in Riyadh have RE. Periodic ophthalmic assessment and refractive services are recommended as part of school health screening initiatives.

The Role of GJD2(Cx36) in Refractive Error Development

Refractive errors are common eye disorders characterized by a mismatch between the focal power of the eye and its axial length. An increased axial length is a common cause of the refractive error myopia (nearsightedness). The substantial increase in myopia prevalence over the last decades has raised public health concerns because myopia can lead to severe ocular complications later in life. Genomewide association studies (GWAS) have made considerable contributions to the understanding of the genetic architecture of refractive errors. Among the hundreds of genetic variants identified, common variants near the gap junction delta-2 (GJD2) gene have consistently been reported as one of the top hits. GJD2 encodes the connexin 36 (Cx36) protein, which forms gap junction channels and is highly expressed in the neural retina. In this review, we provide current evidence that links GJD2(Cx36) to the development of myopia. We summarize the gap junctional communication in the eye and the specific role of GJD2(Cx36) in retinal processing of visual signals. Finally, we discuss the pathways involving dopamine and gap junction phosphorylation and coupling as potential mechanisms that may explain the role of GJD2(Cx36) in refractive error development.

Myopia prevalence in a population-based childhood visual impairment study in North India - CHVI-2

Purpose:

The aim of the study was to determine the prevalence of myopia at the community level.

Methods:

A population-based, cross-sectional study was planned in 40 clusters among children identified with subnormal vision in the urban community of Delhi. House-to-house visits were conducted for visual acuity screening of 20,000 children aged 0–15 years using age appropriate visual acuity charts. All the children with visual acuity of < 6/12 in any eye in the age group between 3 and 15 years and inability to follow light in age group 0–3 years were referred for detailed ophthalmic examination.

Results:

A total of 13,572 (64.7%) children belonged to the age group of 6–15 years. Of these, a total of 507 (3.7%) were found to be having myopia (spherical equivalent of -0.50 DS or worse in one or both eyes) with positive association with higher age groups.

Conclusion:

The estimated prevalence of myopia is 3.7%; the proportion of uncorrected myopia was 45%, which reflects that refractive error services need to be improved further.

Preliminary Evaluation of a Smartphone App for Refractive Error Measurement

Purpose

The purpose of this study was to evaluate the potential feasibility of using a smartphone app in myopia screening.

Methods

The app estimates myopic refractive error by measuring the far point distance for reading three 20/20 Tumbling E letters. In total, 113 myopic subjects with astigmatism no greater than -1.75 diopters (D) were enrolled from 5 sites. The mean age was 22 ± 8.5 years. The app measurement was compared with noncycloplegic subjective refraction measurement or autorefractor if subjective refraction was not available. In addition, 22 subjects were tested with the app for repeatability.

Results

For 201 eyes included, the range of spherical equivalent refraction error was 0 to -10.2 D. The app measurement and clinical measurement was highly correlated (Pearson R = 0.91, P < 0.001). There was a small bias (0.17 D) in the app measurement overall, and it was significantly different across the 5 sites due to different age of subjects enrolled at those sites (P = 0.001) - young adults in their 20s were underestimated the most by 0.49 D, whereas children were overestimated by 0.29 D. The mean absolute deviation of the app measurement was 0.65 D. The repeatability of multiple testing in terms of 95% limit of agreement was ±0.61 D.

Conclusions

Overall, the app measurement is consistent with clinical measurement performed by vision care professionals. The repeatability is comparable with that of some autorefractors. Age-associated human factors may influence the app measurement.

Translational Relevance

The app could be potentially used as a mass screening tool for myopia.