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.

A situational analysis of clinical refraction services in the capital city of the Maldives

Background

Uncorrected refractive error is a leading cause of visual impairment globally. This study aimed to determine the current state of clinical refraction services and barriers to service provision in the capital city of the Maldives.

Methods

This cross-sectional, descriptive-analytical study used a purposive sampling technique. The list of facilities providing refraction services in the city of Malé was compiled through a desk review and finalized after verification by personnel from the Ministry of Health. The availability of human resources and infrastructure was measured using a pre-coded questionnaire that also listed barriers to service provision, followed by on-site observations and subsequent data analysis.

Results

Three clinical ophthalmology departments within hospitals, two ophthalmology hospitals, and nine primary eye care centers were selected for this study. The private sector (n = 12, 85.7%) was the primary provider of refractive error services. All facilities possessed the essential equipment required for refraction. Only optometrists and ophthalmologists conducted refraction. Contact lens assessment and low vision services were not available at any facility. The number of refractions conducted in Malé annually was 145,392. Human resources and management-related factors were the major barriers to the provision of clinical refraction services (n = 21, 44.7%).

Conclusions

Accessibility to refractive error management and low vision services is needed in Malé to meet current population needs. Existing resources, including humans and equipment, require augmentation regarding service provision and enhancement. Knowledge of these barriers could lead to the upscaling of refraction services in Malé, Maldives by health policy makers.

Common causes of visual impairment in the elderly

Background

Aging is not a disease; rather, it is a process. As people age, visual impairment (VI) becomes more common. In 2010, the overall prevalence rate of vision impairment in all races was 25.66% in individuals aged ≥ 80 years, according to the estimate of the National Eye Institute at the National Institutes of Health. This review aimed to address the common causes of VI in the elderly.

Methods

In this narrative review, an electronic search of the PubMed/MEDLINE database was conducted using "visual impairment" and "elderly" for the period between January 2010 and April 2021, to include randomized clinical trials and observational studies concerning VI in the elderly. The selected time period was chosen to provide an updated review.

Results

The search yielded 2955 articles published over the period of more than 11 years. The relevant randomized clinical trials or observational studies were included and reviewed. Cataracts, refractive errors, open-angle glaucoma, age-related macular degeneration, and diabetic retinopathy were the most common age-related ocular disorders leading to VI if untreated in the elderly. The loss of visual acuity can adversely affect quality of life in the elderly. Difficulty with activities of daily living related to VI can lead to social isolation, depression, and anxiety. Loss of vision in the elderly is linked to an increased risk of falls, hip fracture, depression, and poor quality of life.

Conclusions

The most common causes of VI in the elderly are cataracts and refractive errors. VI in most ocular diseases is more prevalent in women than in men due to longer lifespan. The overall prevalence of the main causes of VI in the elderly is expected to increase; therefore, health policymakers should consider this when planning for the health-enhancement program of the population.

Identification and critical appraisal of evidence for interventions for refractive error to support the development of the WHO package of eye care interventions: a systematic review of clinical practice guidelines

Purpose

The World Health Organization is developing a Package of Eye Care Interventions (PECI) to support the integration of eye health care into national health programmes. Interventions included in the PECI should be based on robust evidence where available. Refractive error is a leading cause of blindness and vision impairment and is a PECI priority condition. The aim of this study was to provide high‐quality evidence to support the development of the PECI by identifying and critically appraising clinical practice guidelines (CPGs), and extracting recommendations for refractive error interventions.

Methods

We searched for CPGs on refractive error published in the last 10 years. We conducted the searches initially in February and March 2019 and repeated them in March 2020. We evaluated the quality of potentially relevant guidelines using the Appraisal of Guidelines for Research and Evaluation (AGREE) II tool.

Results

We identified 12 high‐quality CPGs relevant to refractive error, written by six organisations from three high‐income countries. Organisations used a variety of frameworks to assess the strength of recommendations based on available evidence, with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) being most common. Vision screening for children aged 3 to 5 years was recommended consistently. Evidence for screening and eye evaluations at other ages was weaker, although ophthalmic professional organisations consistently recommended regular evaluations. Recommendations on optical and laser correction of refractive error were limited and did not consider implications for low resource settings. Interventions for slowing myopia progression in children were recommended, but these will need regular updating as new evidence emerges.

Conclusions

Current high‐quality guidelines on refractive error have been formulated in high‐income countries. Recommendations focused on prevention and treatment of refractive error in low‐and middle‐income countries are lacking. Regular updating of systematic reviews and CPGs is essential to ensure that robust evidence is promptly appraised and incorporated into recommendations for eye health care practitioners.

Automatic Segment and Quantify Choroid Layer in Myopic eyes: Deep Learning based Model

PURPOSE

To report a rapid and accurate method based upon deep learning for automatic segmentation and measurement of the choroidal thickness (CT) in myopic eyes, and to determine the relationship between refractive error (RE) and CT.

METHODS

Fifty-four healthy subjects 20-39 years of age were retrospectively reviewed. Data reviewed included age, gender, laterality, visual acuity, RE, and Enhanced Depth Imaging Optical Coherence Tomography (EDI-OCT) images. The choroid layer was labeled by manual and automatic method using EDI-OCT. A Mask Region-convolutional Neural Network (Mask R-CNN) model, using deep Residual Network (ResNet) and Feature Pyramid Networks (FPN) as a backbone network, was trained to automatically outline and quantify the choroid layer.

RESULTS

ResNet 50 model was adopted for its 90% accuracy rate and 6.97 s average execution time. CT determined by the manual method had a mean thickness of 258.75 ± 66.11 µm, a positive correlation with RE (r = 0.596, p < .01) and significant association with gender (p = .011) and RE (p < .001) in multivariable linear regression analysis. Meanwhile, CT determined by deep learning presented a mean thickness of 226.39 ± 54.65 µm, a positive correlation with RE (r = 0.546, p < .01) and significant association with gender (p = .043) and RE (p < .001) in multivariable linear regression analysis. Both methods revealed that CT decreased with the increase in myopic RE.

CONCLUSIONS

This deep learning method using Mask-RCNN was able to successfully determine the relationship between RE and CT in an accurate and rapid way. It could eliminate the need for manual process, while demonstrating a feasible clinical application.

Refractive Outcome of Phacoemulsification Cataract Surgery in Rural Sabah Using Immersion Biometry

Background

A good refractive outcome after cataract surgery indicates adequate clinical service provision. Precise immersion biometry is critical to achieve the desired refractive outcome. While the immersion biometry results are good in the tertiary settings, it is of interest to explore the refractive outcome of cataract surgeries in a rural facility using the same technique.

Methods

A retrospective cross-sectional review was conducted on medical records of all cataract surgeries carried out in Hospital Keningau, Sabah. This study used all patients' medical records who had been assessed using immersion biometry pre-operatively, underwent phacoemulsification cataract surgery besides attending a post-operative refraction session within 90 days from the operation date. Clinical details were recorded in the form of standard proformas and analysed. The refractive outcome was evaluated using spherical equivalence (SE) and best-corrected visual acuity (BCVA). The percentage of cases with post-operative SE within ±1.00 diopter (D) and BCVA of '6/12 or better' were determined. The association between demographic factors and surgical-related factors with post-operative SE was evaluated using Fisher's exact test.

Results

Of 140 cataract surgeries, 113 fulfilled the inclusion criteria. The average patient age was 66.3 (SD = 10.9) years old. The technique was proven to replicate a good outcome of 84.1% of cases with post-operative SE within ±1.00 D while 90.3% of the cases achieved BCVA of '6/12 or better'. Age and ethnicity were found to be associated with post-operative SE.

Conclusion

The study proves the reproducibility of good refractive outcome in a rural facility using immersion biometry. The findings provide a benchmark for performance surveillance in rural facilities.

Positions of the horizontal and vertical centre of rotation in eyes with different refractive errors

Purpose

To determine how the position of the centre of rotation of the eyeball is related to axial length and refractive error when horizontal and vertical eye movements are performed.

Methods

A custom‐built eye tracker was used that determined the centre of rotation of the eye (COR) from lateral displacements of the pupil centre. Horizontal and vertical eye movements were studied in the right eyes, and each measurement performed five times in 59 subjects (32 females) with an average age of 36.6 ± 9.1 years. Spherical equivalent refractive errors ranged from −9.7 to +6.8 D with an average error of −1.5 ± 2.9 D. Axial lengths were measured with the ZEISS IOL Master 500.

Results

The mean horizontal centre of rotation (COR) of the right eye for a saccade from 0° to ±11.9° was 15.3 ± 1.5 mm behind the corneal apex, while the average vertical COR for the same angle of eccentricity was 12.5 ± 1.4 mm, indicating that the horizontal COR was 2.8 ± 1.7 mm behind the vertical COR. In right eyes, horizontal COR was significantly correlated with axial length (r = 0.28, p = 0.02) but not with the spherical equivalent refractive error (r = 0.39, p = 0.90). Similarly, vertical COR was significantly correlated with axial length (r = 0.25, p = 0.03) but not with the spherical equivalent refractive error (r = 0.17, p = 0.90).

Conclusions

While it might be expected that the COR is dependent on axial length, the correlation was not strong. Interestingly, the location of the COR was substantially different for horizontal and vertical eye movements which may relate to the flatter curvature of the eyeball in the vertical meridian, compared to the horizontal, as described in previous studies.

Practice patterns in the management of amblyopia among optometrists in Ghana

Despite internationally recognized guidelines, amblyopia management varies among eye care professionals worldwide. Hence, we sought to investigate the practice patterns of amblyopia management and the factors associated with the decision to treat amblyopia among optometrists in Ghana. A cross-sectional survey was conducted among registered optometrists in Ghana from January 2020 to October 2020. Data collection was done through the administration of online questionnaires via e-mail (google form). The structured questionnaires included demographic information, mode, and scope of practice, diagnostic criteria, examination procedures, treatment modalities, and prognosis. A p value of less than 0.05 was deemed statistically significant. The mean (±SD) age of all the 168 respondents was 32.6 (±6.1) years (range: 24-50 years). The majority of the optometrists (64.9%) treated amblyopia in their practice; with the most prevalent being refractive amblyopia (68.2%), followed by strabismic amblyopia (27.1%), then form-deprivation amblyopia (4.7%). Most (76.1%) amblyopic patients presented with symptomatic squinting. The most common ocular and medical history was anisometropia (90.0%), and the most common diagnostic procedures were patient history, visual acuity, and refraction. Optical correction (88.3%) was mainly prescribed for amblyopia treatment, followed by patching (58.5%). Nearly half of the respondent (45.0%) reported good prognosis after amblyopia treatment. After statistical adjustment, female optometrists were significantly associated with decreased odds of treating amblyopia (AOR = 0.36, p = .004). Refractive amblyopia is the main type of amblyopia managed by optometrists in Ghana. Hence, optical correction is the primary treatment regime. Current amblyopia management practice among optometrists adhere to recommended guidelines and our findings demonstrate uniformity in the standard of care.

Early onset X-linked female limited high myopia in three multigenerational families caused by novel mutations in the ARR3 gene

This study describes the clinical spectrum and genetic background of high myopia caused by mutations in the ARR3 gene. We performed an observational case series of three multigenerational families with high myopia (SER≤-6D), from the departments of Clinical Genetics and Ophthalmology of a tertiary Dutch hospital. Whole-exome sequencing (WES) with a vision-related gene panel was performed, followed by a full open exome sequencing. We identified three Caucasian families with high myopia caused by three different pathogenic variants in the ARR3 gene (c.214C>T, p.Arg72*; c.767+1G>A; p.?; c.848delG, p.(Gly283fs)). Myopia was characterized by a high severity (<-8D), an early onset (<6 years), progressive nature, and a moderate to bad atropine treatment response. Remarkably, a female limited inheritance pattern was present in all three families accordant with previous reports. The frequency of a pathogenic variant in the ARR3 gene in our diagnostic WES cohort was 5%. To conclude, we identified three families with early onset, therapy-resistant, high myopia with a female-limited inheritance pattern, caused by a mutation in the ARR3 gene. The singular mode of inheritance might be explained by metabolic interference due to X-inactivation. Identification of this type of high myopia will improve prompt myopia treatment, monitoring, and genetic counseling.

The UCI EyeMobile Preschool Vision Screening Program: Refractive Error and Amblyopia Results from the 2019-2020 School Year

Purpose

To introduce the University of California Irvine (UCI) EyeMobile for Children preschool vision screening program and describe the ophthalmic examination results of children who failed screening with the PlusoptiX S12C photoscreener during one school year.

Patients and Methods

Children aged 30-72 months were screened with the PlusoptiX using ROC mode 3 during the 2019-2020 school year. Children who failed screening were referred for comprehensive eye examination on the EyeMobile mobile clinic. Presence of amblyopia risk factors (ARFs), amblyopia, and refractive error was determined via retrospective review of records. Amblyopia was defined as unilateral if there was ≥ 2-line interocular difference in the best-corrected visual acuity (BCVA) and as bilateral if BCVA was < 20/50 for children < 4 years old and < 20/40 for children ≥ 4 years old. ARFs were defined using 2021 American Association for Pediatric Ophthalmology and Strabismus (AAPOS) instrument-based screening guidelines.

Results

5226 children were screened during the study period. Of the 546 children who failed screening, 350 (64%) obtained consent and were examined. Mean age of examined children was 4.45 years. Amblyopia was found in 8% of examined children, with unilateral amblyopia seen in 79% of amblyopic subjects. Glasses were prescribed to 246 (70.3%) children. Of the 240 children who received cycloplegic examinations, 43% had hyperopia and 30% had myopia. The positive predictive value (PPV) of the PlusoptiX screening for ARFs in children who received cycloplegic examinations was 70.4%.

Conclusion

A significant proportion of Orange County preschoolers with refractive errors and amblyopia have unmet refractive correction needs. The PlusoptiX S12C photoscreener is an adequate screening device for the UCI EyeMobile for Children program, although modification of device referral criteria may lead to increased PPV. Further research is necessary to understand and overcome the barriers to childhood vision care in our community.

Study on stereoacuity and associated factors in school children aged 7 to 14 years

Purpose:

The study aimed to estimate the prevalence of subnormal stereoacuity in school children and to assess the factors associated with it.

Methods:

In this prospective cross-sectional study, a total of 2,376 school children without amblyopia and manifest squint were screened by the titmus fly test, Snellen chart, tests for heterophoria, anterior segment examination, and fundoscopy. Children with a manifest squint, amblyopia (best-corrected visual acuity [BCVA] <6/18), and history of ocular trauma or surgery, and one-eyed children were excluded. Cycloplegic refraction was done in children with uncorrected or undercorrected refractive errors, and stereoacuity was assessed again with spectacle correction.

Results:

The prevalence of normal stereoacuity by titmus fly test was 93.18% with correction of refractive errors. Girls had slightly better stereopsis compared with boys. The subnormal stereoacuity was significantly associated with refractive error (P < 0.00001, significant at P < 0.05), unilateral refractive error (P < 0.00001, significant at P < 0.05), bilateral refractive error (P < 0.00001, significant at P < 0.05), anisometropia (P < 0.00001, significant at P < 0.05), ametropia (P < 0.00001, significant at P < 0.05), lower BCVA (P < 0.00001, significant at P < 0.05), hyperopia (P < 0.05, significant at P < 0.05), and heterophoria (P = 0.014, significant at P < 0.05). The subnormal stereoacuity was positively correlated with the magnitude of refractive error of the eyes.

Conclusion:

This study underlines the significant impact of identification and correction of refractive errors and squints in school children. The measurement of stereoacuity will be of immense importance and must be included in the screening programs for children.

Burden of ocular morbidities and color blindness among school-attending children in a foothill town of Uttarakhand State

Purpose

To estimate prevalence of common ocular morbidities including color blindness among school-attending children of an urban foothill town of Uttarakhand State in Northern India.

Methods

A cross-sectional study was conducted among school-going children of age group 6-16 years of standard I-XII. Schools were selected using population proportionate to the size sampling technique. Detailed ocular examination including color vision and unaided or aided visual acuity for various ocular morbidities was done. Data was entered into MS excel with statistical analysis using SPSS version 23 with significant P value <0.05.

Results

In total, 13,492 students (mean age 10.9 ± 2.7 years) with almost equal male to female ratio were screened. Overall prevalence of ocular morbidity was 23.2%, with refractive error (18.5%) on top, followed by color blindness (2.2%). The later was observed more among males (3.0%) as compared to females (1.4%) with significantly higher odds, OR = 2.3 (1.7-2.9) (P < 0.001).

Conclusion

Refractive error has been the most common ocular morbidity, followed by color blindness. Earliest detection can prevent permanent disability and disappointment among youngsters when rejected from entering certain professions due to color vision defect.

Association Between Types of Posterior Staphyloma and Refractive Error After Cataract Surgery for High Myopia

Purpose: To investigate the association between different types of posterior staphyloma (PS) and refractive error (RE) after cataract surgery in patients with high myopia.

Methods: This retrospective study included 113 eyes of 113 highly myopic patients with PS. PS was detected using a wide-field fundus imaging system. PS was classified into wide macular, narrow macular, and other types. RE equaled the actual spherical equivalent (SE) minus the targeted SE values 3 months after cataract surgery.

Results: The rates of wide macular, narrow macular, and other types of PS were 46.02, 39.82, and 14.16%, respectively. There were no significant differences in best corrected distance visual acuity (BCDVA) or SE among the three classifications of PS before cataract surgery (P > 0.05). However, postoperative BCDVA and SE were significantly different among the three types of PS patients (P < 0.05). The average RE values were 0.98 ± 1.00 D, 0.19 ± 0.87 D, 0.13 ± 0.59 D, respectively; the statistical differences of RE were <0.01, <0.01, and 0.81 (wide macular vs. narrow macular, wide macular vs. other types, narrow macular vs. other types), respectively. Multivariate linear regression analysis revealed that higher hyperopia RE after surgery was associated with wide macular staphyloma (P < 0.001), more myopic SE (P = 0.003), and increased BCDVA (P = 0.002) before surgery.

Conclusions: Wide macular PS may be associated with more hyperopic RE; it may serve as a critical biomarker of hyperopic RE after cataract surgery in highly myopic patients.

Cataract Surgery in Short Eyes, Including Nanophthalmos: Visual Outcomes, Complications and Refractive Results

Background

To report the visual outcomes, complications and refractive results of phacoemulsification surgery and intraocular lens implantation in a large series of adult patients with short and nanophthalmic eyes.

Methods

The records of all patients with axial length <21.0 mm undergoing phacoemulsification with intraocular lens implantation at an adult teaching hospital were retrospectively reviewed. The main outcome measures were corrected distance visual acuity and refraction at 90 days after surgery and intra- and postoperative complications occurring during the follow-up period.

Results

A total of 71 eyes of 51 patients (median age 71 years, interquartile range 62–75.5) were included. Surgery resulted in an improvement in corrected distance visual acuity in 53 eyes (74.6%) (95% confidence interval, logMAR 0.11–0.29) and was logMAR 0.30 or better in 47 eyes (66.2%). Worsening of corrected distance visual acuity occurred in 9 eyes (12.7%). Median postoperative refractive error was −0.75 dioptres. SRK/T and Kane formula were more accurate in predicting postoperative refraction than Barrett Universal II and Hoffer Q when based on mean absolute error (P < 0.005). Complications occurred in 18 eyes (25.4%). The most frequent complications were iris prolapse, Descemet’s membrane and/or endothelial trauma, transient severe corneal edema and cystoid macular edema. There was no statistically significant difference in complication rates between senior surgeons and senior trainees (P = 0.66).

Conclusion

Cataract surgery in short and nanophthalmic eyes is challenging with a higher complication rate than routine cataract surgery, but frequently results in good visual outcomes. Postoperative refractive outcomes are more difficult to predict in this cohort.

Development and validation of competency framework for teaching management of refractive errors: A participatory Delphi approach

Purpose:

Competency-based education and assessment are globally trending, also embraced by recently announced National education policy 2020, India. Medical programs are rapidly transforming to produce competent health professionals, to satisfy public health requirements. This paper describes Delphi study with a participatory approach, to develop a competency matrix required for training of eye care professionals.

Methods:

Scoping review of literature formulated the baseline architecture of competency framework identifying two core competencies for management of refractive error, namely, “visual function assessment” and “optical technology management.” The Delphi technique was employed for the development of a competency matrix with detailed knowledge, skills, and attitude (KSA) definitions for all competency elements. A heterogeneous group including optometry practitioners, academicians, researchers, association representatives, and industry representatives accomplished the objective in four rounds.

Results:

Delphi study resulted in defining two competency clusters (CC): “CC1: Refraction” with 10 units and 43 elements and “CC2: Dispensing optics” with 8 units and 54 elements. KSA components of each of competency elements were identified and mapped with applied optics curriculum in the optometry program.

Conclusion:

Participation of all stakeholders of the educational system is essential and beneficial for nurturing of the competent workforce in healthcare. It helps build a curriculum not only having theoretical knowledge and skills but also the attitude and behavioral component of measurable competencies that satisfies the needs of the local healthcare system. This study has evolved a comprehensive competency matrix highlighting essential competencies required for the effective management of refractive error.

Refractive Error and Eye Health: An Umbrella Review of Meta-Analyses

Purpose: To explore the associations between refractive errors and multiple eye health outcomes. Methods: This is an umbrella review based on systematic reviews with meta-analyses. In our study, refractive errors included myopia, hyperopia, astigmatism, and anisometropia. We reconducted the meta-analyses whose primary data were available in sufficient detail by random effect model. Heterogeneity was assessed by I ². The main outcomes included myopic macular degeneration (MMD), retinal detachment (RD), cataract, open-angle glaucoma (OAG), strabismus, age-related macular degeneration (AMD), and diabetic retinopathy (DR). Results: Myopia was associated with increased risk of MMD (relative risk = 102.11, 95% CI 52.6-198.22), RD (3.45, 1.08-11.00), nuclear cataract (2.15, 1.53-3.03), posterior subcapsular (PSC) cataract (1.74, 1.41-2.15), OAG (1.95, 1.74-2.19), exotropia (5.23, 2.26-12.09), but decreased risk of DR (0.83, 0.66-1.04), and early AMD (0.80, 0.67-0.94). From mild-to-high myopia, the association strengthened for MMD, RD, nuclear cataract, PSC cataract, OAG, and DR. Hyperopia was associated with an increased risk of early AMD (1.09, 1.01-1.18) and esotropia (22.94, 10.20-51.62). Astigmatism and anisometropia were associated with increased risk of both exotropia and esotropia. Conclusions: Myopia, especially high myopia, demonstrated the highest risk for eye health outcomes, such as MMD, RD, OAG, nuclear and PSC cataracts, and exotropia. However, myopia was associated with a lower risk of early AMD and DR. Individuals with hyperopia are more likely to suffer early AMD and esotropia. Astigmatism and anisometropia predispose to strabismus. A lot of research studies on the mechanism of the associations are needed. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=239744; identifier: 239744.

Refractive amblyopia among children aged 4-12 years in a hospital-based setting in Gaza Strip, Palestine

Background

Refractive amblyopia is the most common cause of amblyopia in the Gaza Strip. However, the pattern of this condition has not yet been studied in this region. This study aimed to determine the pattern of refractive amblyopia in Gazan children aged 4‒12 years.

Methods

This was a hospital-based cross-sectional study using a purposive sampling method. Children aged 4‒12 years who attended the Children's Unit at Gaza Ophthalmic Hospital, Gaza Strip, Palestine from September 2019 to July 2020, were examined. A comprehensive eye test was conducted for all participants. Those who failed the eye examinations and were diagnosed with refractive amblyopia were included in the study. Demographic data and amblyopic refractive error patterns were analyzed accordingly.

Results

Of the 107 children, 72.9% were newly diagnosed with refractive amblyopia. The mean (standard deviation [SD]) of age of the children who participated was 7.85 (1.55) years. Approimately two-thirds of the patients were female (57.9%). Unilateral amblyopia was predominant in 60.7% of the cases. Moderate amblyopia was common (81.9%). A total of 149 amblyopic eyes were examined in total, with a mean (SD) (range) of best-corrected distance visual acuity and spherical equivalent of 0.45 (0.19) (0.2 to 1.3) logarithm of the minimum angle of resolution and + 0.76 (4.51) diopters (- 10.25 to + 11.50). Astigmatism was the most common amblyogenic factor (53.7%) among children with amblyopia.

Conclusions

The frequency of refractive amblyopia was 72.9%, and meridional amblyopia accounted for the highest percentage. Girls were more commonly affected than boys. The majority were in the 7-year-old age group. Most cases were unilateral with moderate refractive amblyopia. Our study yields insights into the patterns of refractive amblyopia among children in the Gaza Strip.

Effect of Cycloplegia on Refractive Error Measure in Chinese School Students

PURPOSE

To determine differences in cycloplegic vs. non-cycloplegic refractive error and factors associated with these differences in Chinese school students.

METHOD

In this cross-sectional school-based study, refractive error was measured in school students using a NIDEK autorefractor before and after administration of 0.5% tropicamide. Spherical equivalent (SER) in diopters (D) was calculated as sphere plus half cylinder. SER differences before vs. after cycloplegia were evaluated using mean, standard deviation (SD), 95% limits of agreement. Univariable and multivariable regression models were used to determine factors associated with SER differences.

RESULTS

Among 3604 students, 3450 (95.7%) provided data for analysis. Mean age (SD) was 9.7 (3.6) years. The mean SER (SD) was -1.12 (1.97) D before cycloplegia, and -0.20 (2.19) D after cycloplegia, with a mean difference of 0.92 D (95% limits of agreement: -0.93 to 2.78 D). Among 196 eyes with non-cycloplegic SER -6.0 D or worse (e.g., met high myopia definition), 71.4% had cycloplegic SER -6.0 D or worse, and among 3607 eyes with non-cycloplegic SER -0.5 D or worse (e.g., met myopia definition), 62.1% eyes had cycloplegic SER -0.5 D or worse. Cycloplegic SER was more correlated with axial length than non-cycloplegic SER (Pearson r = 0.82 vs. 0.72, p < .0001). In multivariable analysis, larger SER differences were associated with more hyperopic refractive error and smaller axial length (all p < .0001).

CONCLUSION

Non-cycloplegic refractive error overestimates myopia by approximately one diopter. This overestimation increases with more hyperopic refractive error and smaller axial length. Non-cycloplegic refractive error should not be used for evaluating pediatric myopia.

ABBREVIATIONS

BCVA = best corrected visual acuity; D = diopter; SD = standard deviation; SE = standard error; SER = spherical equivalent; CI = confidence interval.

Age-related changes in the fractal dimension of the retinal microvasculature, effects of cardiovascular risk factors and smoking behaviour

Purpose

This cross‐sectional study investigates the association between retinal vessel complexity and age and studies the effects of cardiovascular health determinants.

Methods

Retinal vessel complexity was assessed by calculating the box‐counting fractal dimension (D_f) from digital fundus photographs of 850 subjects (3–97 years). All photographs were labelled as ‘non‐pathological’ by the treating ophthalmologist.

Results

Statistical models showed a significantly decreasing relationship between age and D_f (linear: R‐squared = 0.1897, p < 0.0001; quadratic: R‐squared = 0.2343, p < 0.0001; cubic: R‐squared = 0.2721, p < 0.0001), with the cubic regression model offering the best compromise between accuracy and model simplicity. Multivariate cubic regression showed that age, spherical equivalent and smoking behaviour have an effect (p < 0.0001) on D_f. A significantly increasing effect of the number of pack‐years on D_f was observed (effect: 0.0004, p = 0.0017), as well as a significantly decreasing effect of years since tobacco abstinence (effect: −0.0149, p < 0.0001).

Conclusion

We propose using a cubic trend with age, refractive error and smoking behaviour when interpreting retinal vessel complexity.

Expected vs. Actual Refractive Error in Patients Presenting With Phacomorphic Glaucoma

Aim

Phacomorphic glaucoma (PG) is a rare but clinically significant presentation requiring emergent cataract surgery. We chose to investigate whether the expected refractive error based on the intraocular lens (IOL) calculations differed from the expected refractive outcome post-surgery.

Materials & Methods

A retrospective analysis of patients with PG between 2009 to 2018 who underwent cataract surgery and had postoperative refraction was included. Information collected included presenting and postoperative best-corrected visual acuity (BCVA), intraocular pressure (IOP) pre­ and postoperatively, and the presence of corneal edema. Predicted spherical equivalence (SphEq) data was collected from IOL calculations, and postoperative SphEq was calculated from postoperative manifest refraction.

Results

Twenty patients with PG who underwent cataract surgery were identified; of these, 10 patients and 10 eyes who underwent manifest refraction post­op were included. Mean BCVA at presentation was 20/544 [Logarithm of Minimal Angle of Resolution (LogMAR) 1.44], and mean pre-op IOP was elevated at 24.6 ± 14.2 mmHg. Mean BCVA measured at one month post-op improved to 20/192 (LogMAR 0.983). Mean IOP decreased to 19 ± 8.8 mmHg at one month post-op. The mean difference between the predicted and actual refractive error, as calculated by SphEq was ­0.088 (p=0.570).

Conclusion

The study shows an improvement in visual acuity and IOP post-cataract surgery in patients with PG, as would be expected. The study also demonstrates that patients ended up with a slightly more myopic refractive error than expected postoperatively, and illustrates the clinical variability in postoperative refractive outcomes from a large standard deviation. This is a new and clinically important finding, although not statistically significant, that has not been previously published.

The effect of spatially-related environmental risk factors in visual scenes on myopia

Myopia, the most common refractive error, is estimated to affect over two billion people worldwide, especially children from East Asian regions. Children with early onset myopia have an increased risk of developing sight threatening complications in later life. In addition to the contribution of genetic factors, of which expression is controversially suggested to be subject to environmental regulation, various environmental factors, such as near-work, outdoor, and living environment, have also been determined to play significant roles in the development of refractive error, especially juvenile myopia. Cues from daily visual scenes, including lighting, spatial frequency, and optical defocus over the field of visual stimuli, are suggested to influence emmetropisation, thereby affecting myopia development and progression. These risk factors in visual scenes of the everyday life may explain the relationship between urbanicity and myopia prevalence. This review first summarises the previously reported associations between myopia development and everyday-life environments, including schooling, urban settings, and outdoors. Then, there is a discussion of the mechanisms hypothesised in the literature about the cues from different visual scenes of urbanicity in relation to myopia development.

The Prevalence of Visual Impairment and Refractive Errors among a Youth Population in Mozambique: Evidence of the Need for Intervention

Visual impairment (VI) can significantly interfere in the child's daily activities and quality of life, having a negative effect on their development and learning. The aim of the study was to determine the prevalence of VI and associated demographic factors in students examined during the program "Moçambique te vejo melhor". This study was cross-sectional and retrospective, based on the 2018/19 edition of the program. Eye examinations were performed in secondary school students, aged between 12 and 20 years, of five districts in Nampula province. The examination included visual acuity, non-cycloplegic refraction and assessment of the anterior and posterior segment and ocular adnexa. The prevalence of uncorrected, presenting and best-corrected VI found was 18.3%, 10.8%, and 5.0%, respectively. Refractive error (RE) had a prevalence of 24.7%, and the age groups between 15-17 years and 18-20 years were significantly associated with myopia (with OR: 4.9 and OR: 8.8, respectively), as well as the 11th and 12th grade (OR: 8.1 and OR: 10.7, respectively), and Malema district had association with myopia (ORa: 0.4) and hyperopia (ORa: 0.4 and OR: 0.3) as a protective factor. The prevalence of RE and VI was relatively high, showing the need for greater intervention at the school level.

Is myopia prevalence related to outdoor green space?

PURPOSE

Rapid urbanisation and lifestyle changes have been associated with a huge increase in myopia across many parts of the world. There is strong evidence that environmental factors including time outdoors and urbanisation can influence the development of myopia, particularly in school-aged children. The aim of this study is to determine whether there is a relationship between the prevalence of myopia and the amount of vegetation/green spaces across different regions of the world, as a risk factor for myopia development.

METHODS

The prevalence of myopia in the 15 to 19-year age group in Australia, Brazil, China, Finland, India, Iran, Japan, Oman, Singapore, South Africa and the UK was obtained from a meta-analysis by Holden et al. Normalised Difference Vegetation Index (NDVI) was used to quantify green space exposure based on Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite data. Green space was measured in locations specific to 15 studies that reported myopia prevalence. Simple linear regression was used to analyse yearly data, and a mixed effects model was applied to assess the significance of green space when study was a random effect.

RESULTS

Myopia prevalence increases significantly when green space was <-0.2, but the effect was less apparent for values >-0.1. When a mixed effects model was used, the effect of green space was found to be significantly associated with myopia prevalence (p = 0.05).

CONCLUSIONS

There was evidence of a weak but significant non-linear relationship between myopia and green space, with the effect most apparent at low levels of green space. A larger data sample, along with further investigations into the utilisation of green spaces, are required to understand whether increasing the amount of green space can reduce myopia incidence and progression impact.

The relationship between serum zinc levels and myopia

CLINICAL SIGNIFICANCE

Nutritional status influences growth and development, including that of the eye. However, little attention has been given to possible dietary influences in myopia. This study demonstrates that serum zinc has no relationship with myopia development.

BACKGROUND

Myopia is inherently associated with eye growth and thereby possibly amenable to nutritional influence. A number of Asian studies have reported lower levels of serum zinc in myopic children. This study was designed to assess the relationship between serum zinc and myopia in the Korean population - using a subsample of participants from nationally representative data.

METHODS

Data from the fifth Korea National Health and Nutrition Examination Survey (KNHANES) 2010 were used to explore zinc status in relation to refraction. A total of 304 participants were analysed, ranging in age from 12 to 19-years. Serum zinc levels were measured using inductively coupled plasma mass spectrometry, while refractive error was determined by non-cycloplegic autorefraction. Multivariate analysis was used to examine the association.

RESULTS

A significant majority of participants (n = 255; 84 per cent) were myopic. There was no significant difference in serum zinc levels between myopic and non-myopic children (p = 0.81). In multivariate logistic regression, serum zinc was not significantly associated with myopia after adjustment for age, gender, residence, body mass index, family income and recreational activity. Similarly, no relationship was observed between spherical equivalent refraction and serum zinc within the myopic group (p = 0.46).

CONCLUSION

In a subset of 12-19-year-old participants from the population-representative KNHANES study, no association was found between serum zinc and myopia. However, the lack of a sensitive biomarker for zinc status remains a major limitation in this, and all current studies.