Synthetic artificial intelligence using generative adversarial network for retinal imaging in detection of age-related macular degeneration.

Introduction: Age-related macular degeneration (AMD) is one of the leading causes of vision impairment globally and early detection is crucial to prevent vision loss. However, the screening of AMD is resource dependent and demands experienced healthcare providers. Recently, deep learning (DL) systems have shown the potential for effective detection of various eye diseases from retinal fundus images, but the development of such robust systems requires a large amount of datasets, which could be limited by prevalence of the disease and privacy of patient. As in the case of AMD, the advanced phenotype is often scarce for conducting DL analysis, which may be tackled via generating synthetic images using Generative Adversarial Networks (GANs). This study aims to develop GAN-synthesized fundus photos with AMD lesions, and to assess the realness of these images with an objective scale. Methods: To build our GAN models, a total of 125,012 fundus photos were used from a real-world non-AMD phenotypical dataset. StyleGAN2 and human-in-the-loop (HITL) method were then applied to synthesize fundus images with AMD features. To objectively assess the quality of the synthesized images, we proposed a novel realness scale based on the frequency of the broken vessels observed in the fundus photos. Four residents conducted two rounds of gradings on 300 images to distinguish real from synthetic images, based on their subjective impression and the objective scale respectively. Results and discussion: The introduction of HITL training increased the percentage of synthetic images with AMD lesions, despite the limited number of AMD images in the initial training dataset. Qualitatively, the synthesized images have been proven to be robust in that our residents had limited ability to distinguish real from synthetic ones, as evidenced by an overall accuracy of 0.66 (95% CI: 0.61-0.66) and Cohen's kappa of 0.320. For the non-referable AMD classes (no or early AMD), the accuracy was only 0.51. With the objective scale, the overall accuracy improved to 0.72. In conclusion, GAN models built with HITL training are capable of producing realistic-looking fundus images that could fool human experts, while our objective realness scale based on broken vessels can help identifying the synthetic fundus photos.

Intraoperative optical coherence tomography guided iris stromal cyst treatment with absolute alcohol injection.

Purpose: To report on the utility of intraoperative optical coherence tomography (iOCT) in the treatment of a traumatic iris cyst with aspiration and alcohol injection. Observations: A 61-year-old male, with a past ocular history of a left corneoscleral laceration in 1982, presented with gradual onset of blurring of vision in 2021. Examination revealed a large iris stromal cyst. He subsequently underwent iOCT guided iris stromal cyst aspiration and absolute alcohol injection. Conclusions and importance: Our case demonstrated the efficacy of iOCT to aid in direct visualization and safe guidance of the alcohol into the iris cyst, reducing the risk of collateral damage.

Normative profiles of neuroretinal rim area in a multiethnic Asian population: the Singapore Epidemiology of Eye Diseases study.

AIMS: To evaluate the normative profiles for neuroretinal rim area (RA) in a multiethnic Asian population. METHODS: Subjects were recruited from the Singapore Epidemiology of Eye Diseases (2009-2015) study and underwent standardised examinations. RA measurements were performed using Cirrus high-definition optical coherence tomography (Carl Zeiss Meditec). Multivariable linear regression with generalised estimating equation model was used to evaluate the associations between demographic, systemic and ocular factors with RA. RESULTS: A total of 9394 eyes from 5116 subjects (1724 Chinese, 1463 Malay, 1929 Indian) were included in the final analysis. The mean (±SD) of RA was 1.28 (±0.23) mm2 for Chinese, 1.33 (±0.26) mm2 for Malays, and 1.23 (±0.23) mm2 for Indians. The 5th percentile value for RA was 0.94 mm2 for Chinese, 0.96 mm2 for Malay, and 0.89 mm2 for Indian. In multivariable analysis, following adjustment for age, gender, body mass index, diabetes mellitus, hyperlipidaemia, history of cataract surgery, axial length, intraocular pressure (IOP) and disc area, Indian eyes have smaller RA when compared with Malays (ß=-0.074; 95% CI -0.090 to -0.058; p<0.001) and Chinese (ß=-0.035; 95% CI -0.051 to -0.019; p<0.001), respectively. Additionally, older age (per decade, ß=-0.022), male gender (ß=-0.031), longer axial length (per mm, ß=-0.025), spherical equivalent (per negative dioptre, ß=-0.005), higher IOP (per mm Hg, ß=-0.009) were associated with smaller RA (all p≤0.004). CONCLUSION: In this multiethnic population-based study, we observed significantly smaller RA in Indian eyes, compared with Chinese and Malays. This indicates the need of a more refined ethnic-specific RA normative databases among Asians.

Inter-relationship between ageing, body mass index, diabetes, systemic blood pressure and intraocular pressure in Asians: 6-year longitudinal study.

BACKGROUND: To investigate the biological effect of ageing on intraocular pressure (IOP) and risk factors in a population-based cohort study of Malay and Indian adults. METHODS: Participants aged 40-80 years were recruited for baseline and 6-year follow-up visits between 2004-2009 and 2010-2015, respectively. Blood pressure (BP) was measured with an automatic BP monitor and IOP were obtained by Goldmann applanation tonometry. Main outcome was change in IOP, defined as the difference between the 6-year IOP and the baseline IOP. Linear regression models were used to investigate the association of changes in IOP with risk factors. RESULTS: Participants without a history of glaucoma or cataract surgery at baseline were included (n = 3188; mean age: 54±9 years) . Their average IOP was reduced (-0.5±3.1 mm Hg), except for those who developed hypertension at follow-up (0.0±3.1 mm Hg). After adjusting for covariates, changes in IOP were negatively associated with age (ß=-0.07, 95% CI -0.13 to -0.01) and positively associated with body mass index, diabetes, hypertension (normotensive as reference group; newly developed hypertensive (ß=0.67, 95% CI 0.39 to 0.95) and chronic hypertensive (ß=0.46, 95% CI 0.22 to 0.70)), baseline systolic BP (SBP) (ß=0.20, 95% CI 0.14 to 0.26) and diastolic BP (DBP) (ß=0.33, 95% CI 0.22 to 0.44), as well as with 6-year increases in SBP (ß=0.27, 95% CI 0.21 to 0.33) and DBP (ß=0.52, 95% CI 0.41 to 0.63). CONCLUSIONS: Normal ageing and reduced systemic BP are associated with reduced IOP in Malay and Indian adults. Given that high IOP is a risk factor for glaucoma, our finding highlights the importance of controlling hypertension in older adults, where hypertension and glaucoma incidences are on a rise.

Trends of Visual Impairment and Blindness in the Singapore Chinese Population over a Decade.

We evaluated the prevalence of visual impairment (VI) and blindness among Chinese adults in the Singapore Chinese Eye Study (SCES, 2009-2011), and compared the trends with the Tanjong Pagar Survey, Singapore (TPS), conducted a decade earlier. The SCES comprised of 3,353 Chinese adults aged ≥40 years (response rate, 72.8%). Participants underwent standardized examinations, including measurements of presenting, and best-corrected visual acuity (VA). Bilateral VI (VA < 20/40 to ≥20/200) and blindness (VA < 20/200) were defined based on the United States definition (better-seeing eye). Age-standardized prevalence was calculated using the 2010 Singapore Chinese Population Census. Primary causes and factors associated with VI and blindness were evaluated. In SCES, the age-standardized prevalence of presenting bilateral VI and blindness were 17.7% and 0.6%, respectively; the age-standardised prevalence of best-corrected bilateral VI and blindness were 3.4% and 0.2%, respectively. The previous TPS reported similar rates of best-corrected bilateral VI (3.8%) and blindness (0.3%). In SCES, cataract remains the main cause for both best-corrected bilateral VI (76.0%) and blindness (50.0%). Older age, female, lower income, lower educational level, and smaller housing type were associated with presenting bilateral VI or blindness (all P ≤ 0.025). These findings will be useful for the planning of eye care services and resource allocation.

Six-Year Incidence and Risk Factors of Age-Related Macular Degeneration in Singaporean Indians: The Singapore Indian Eye Study.

We aimed to determine the 6-year incidence and risk factors of age-related macular degeneration (AMD) in first and second generations of Singaporean Indians. Baseline examination was conducted in 2007-9 and 6-year propsective follow-up examination of this Indian population in 2013-5. All participants underwent interviews with questionnaires and comprehensive medical and eye examinations. Incidence was age-standardized to Singaporean 2010 census. Risk factors associated with AMD incidence were assessed and compared between first and second generations of immigrants. Among 2200 persons who participated in the follow-up examination (75.5% response rate), gradable fundus photographs were available in 2105. The 6-year age-standardized incidences of early and late AMD were 5.26% and 0.51% respectively. Incident early AMD was associated with cardiovascular disease history (HR 1.59, 95% CI 1.04-2.45), underweight body mass index (BMI) (HR 3.12, 95% CI 1.37-7.14) (BMI of <18.5 vs 18.51-25 kg/m2), heavy alcohol drinking (HR 3.14 95% CI 1.25-7.89) and ARMS2 rs3750847 homozygous genetic loci carrier (HR 2.52, 95% CI 1.59-3.99). We found a relatively low incidence of early AMD in this Singaporean Indian population compared to Caucasian populations. Both first and second-generation Indian immigrants have similar incidence and risk factor patterns for early AMD.

Inter-relationship between ocular perfusion pressure, blood pressure, intraocular pressure profiles and primary open-angle glaucoma: the Singapore Epidemiology of Eye Diseases study.

OBJECTIVE: To elucidate the inter-relationship between ocular perfusion pressure (OPP), blood pressure (BP), intraocular pressure (IOP) profiles and primary open-angle glaucoma (POAG) in a multiethnic Asian population. METHODS: Participants were recruited from the Singapore Epidemiology of Eye Diseases Study and underwent standardised ocular and systemic examinations. POAG was defined according to the International Society for Geographical and Epidemiological Ophthalmology criteria. Logistic regression analyses with generalised estimating equation models were performed and used to account for correlation between eyes. RESULTS: A total of 9877 participants (19 587 eyes), including 213 POAG cases (293 eyes) were included. Eyes with lowest quartile levels of systolic OPP (SOPP <110 mm Hg) were 1.85 times (95% CI 1.16 to 2.95) likely to have POAG, compared with eyes with mid-range SOPP levels (123-137 mm Hg; third quartile), after adjusting for relevant covariates and IOP. Consistently, we found that lowest quartile of systolic BP (SBP <124 mm Hg) was 1.69 times (95% CI 1.08 to 2.66) likely to have POAG, compared with mid-range SBP levels (138-153 mm Hg; third quartile). Furthermore, the effect of lower SBP on POAG was more pronounced in eyes with IOP ≥21 mm Hg (OR 3.90; 95% CI 1.24 to 12.30). Both the mean and diastolic profiles of OPP and BP were not significantly associated with POAG, after adjusting for relevant covariates and IOP. CONCLUSIONS: In this population-based sample of nearly 10 000 Asian individuals, we showed that low SOPP was associated with POAG. This association was potentially in part secondary to low SBP and high IOP. Our findings provide further clarity on the roles of OPP surrogates and BP profiles in POAG.

Factors affecting signal strength in spectral-domain optical coherence tomography.

PURPOSE: To identify ocular factors that affect signal strength in spectral-domain optical coherence tomography (SD-OCT). METHODS: Data from 1312 participants of the population-based Singapore Malay Eye Study-2 (SiMES-2) were included in the analysis. All participants underwent standardized ophthalmic examination, including measurements of best-corrected visual acuity (BCVA), refractive error, axial length, corneal curvature and presence of cataracts. Optic disc and macular cube scans were acquired using the Cirrus HD-OCT (software version 6.0, Carl Zeiss Meditec, Dublin, CA, USA). Signal strength of the optical coherence tomography (OCT) scan was recorded for each study eye. Multivariable linear regression analyses were performed to evaluate the associations between ocular factors and signal strength of the OCT scans. RESULTS: The mean (±SD) age of our study participants was 61 ± 9 years, and 44.6% were male. Mean optic disc scan signal strength was 7.90 ± 1.25, range = 0-10, while mean macular scan signal strength was 8.80 ± 1.27, range = 0-10. In multivariable regression analyses, poorer signal strength in optic disc and macular cube scans was each associated with older age (per decade, ß = -0.373, p < 0.001; ß = -0.373, p < 0.001, respectively), poorer BCVA (per logMAR line; ß = -0.123, p < 0.001; ß = -0.156, p < 0.001, respectively), greater degree of myopia (per negative dioptre of spherical equivalent; ß = -0.112, p < 0.001; ß = -0.117, p < 0.001, respectively), presence of cortical cataracts (ß = -0.331, p < 0.001; ß = -0.314, p < 0.001, respectively) and presence of posterior subcapsular cataracts (ß = -0.910, p < 0.001; ß = -0.797, p < 0.001, respectively). CONCLUSION: We found that older age, poorer BCVA, greater degree of myopia and presence of cortical and posterior subcapsular cataracts were associated with reduced signal strength in Cirrus SD-OCT. Our findings provide information on the barriers to obtaining good image quality when using SD-OCT, and allow clinicians to potentially identify individuals who are more likely to have unreliable OCT measurements.

Impact of common genetic determinants of Hemoglobin A1c on type 2 diabetes risk and diagnosis in ancestrally diverse populations: A transethnic genome-wide meta-analysis.

BACKGROUND: Glycated hemoglobin (HbA1c) is used to diagnose type 2 diabetes (T2D) and assess glycemic control in patients with diabetes. Previous genome-wide association studies (GWAS) have identified 18 HbA1c-associated genetic variants. These variants proved to be classifiable by their likely biological action as erythrocytic (also associated with erythrocyte traits) or glycemic (associated with other glucose-related traits). In this study, we tested the hypotheses that, in a very large scale GWAS, we would identify more genetic variants associated with HbA1c and that HbA1c variants implicated in erythrocytic biology would affect the diagnostic accuracy of HbA1c. We therefore expanded the number of HbA1c-associated loci and tested the effect of genetic risk-scores comprised of erythrocytic or glycemic variants on incident diabetes prediction and on prevalent diabetes screening performance. Throughout this multiancestry study, we kept a focus on interancestry differences in HbA1c genetics performance that might influence race-ancestry differences in health outcomes. METHODS & FINDINGS: Using genome-wide association meta-analyses in up to 159,940 individuals from 82 cohorts of European, African, East Asian, and South Asian ancestry, we identified 60 common genetic variants associated with HbA1c. We classified variants as implicated in glycemic, erythrocytic, or unclassified biology and tested whether additive genetic scores of erythrocytic variants (GS-E) or glycemic variants (GS-G) were associated with higher T2D incidence in multiethnic longitudinal cohorts (N = 33,241). Nineteen glycemic and 22 erythrocytic variants were associated with HbA1c at genome-wide significance. GS-G was associated with higher T2D risk (incidence OR = 1.05, 95% CI 1.04-1.06, per HbA1c-raising allele, p = 3 × 10-29); whereas GS-E was not (OR = 1.00, 95% CI 0.99-1.01, p = 0.60). In Europeans and Asians, erythrocytic variants in aggregate had only modest effects on the diagnostic accuracy of HbA1c. Yet, in African Americans, the X-linked G6PD G202A variant (T-allele frequency 11%) was associated with an absolute decrease in HbA1c of 0.81%-units (95% CI 0.66-0.96) per allele in hemizygous men, and 0.68%-units (95% CI 0.38-0.97) in homozygous women. The G6PD variant may cause approximately 2% (N = 0.65 million, 95% CI 0.55-0.74) of African American adults with T2D to remain undiagnosed when screened with HbA1c. Limitations include the smaller sample sizes for non-European ancestries and the inability to classify approximately one-third of the variants. Further studies in large multiethnic cohorts with HbA1c, glycemic, and erythrocytic traits are required to better determine the biological action of the unclassified variants. CONCLUSIONS: As G6PD deficiency can be clinically silent until illness strikes, we recommend investigation of the possible benefits of screening for the G6PD genotype along with using HbA1c to diagnose T2D in populations of African ancestry or groups where G6PD deficiency is common. Screening with direct glucose measurements, or genetically-informed HbA1c diagnostic thresholds in people with G6PD deficiency, may be required to avoid missed or delayed diagnoses.

Is Corneal Arcus Independently Associated With Incident Cardiovascular Disease in Asians?

PURPOSE: To examine the longitudinal relationship between baseline corneal arcus (CA) and incident cardiovascular disease (CVD) in ethnic Indian and Malay adults in Singapore. DESIGN: Population-based cohort study. METHODS: Indian and Malay adults aged 40-80 years were recruited for baseline and 6-year follow-up visits between 2004-2009 and 2010-2015, respectively (follow-up response rate 73.9%). CA was assessed by ophthalmologists using slit-lamp biomicroscopy. The main outcome was self-reported incident CVD, defined as new myocardial infarction, angina pectoris, or stroke, which developed between baseline and follow-up. Multivariable logistic regression models assessed independent associations between baseline CA and incident CVD, adjusting for traditional CVD risk factors including age, sex, serum cholesterol, hypertension, diabetes, and smoking. We further conducted sex-stratified analyses to identify possible effect modifications. RESULTS: Of the total 3637 participants (overall mean [SD] age: 56 [9] years, 46% male) with available follow-up data, without history of CVD at baseline, 208 (5.7%) incident CVD cases were reported. Participants with CA were more likely to have incident CVD (7.5%) than those without (4.9%). After controlling for traditional CVD risk factors, CA was independently associated with incident CVD (odds ratio [95% confidence interval]: 1.52 [1.07-2.16]) in adjusted models. In sex-stratified models, associations between CA and incident CVD were seen in men (1.73 [1.12-2.67]) and not in women (1.05 [0.56-1.97]). CONCLUSIONS: CA is associated with incident CVD, independent of serum lipids and traditional CVD risk factors, in ethnic Malay and Indian men. Our finding suggests that CA is an additional observable indicator of CVD in men.

Association of Systemic Medication Use With Intraocular Pressure in a Multiethnic Asian Population: The Singapore Epidemiology of Eye Diseases Study.

IMPORTANCE: There is limited understanding of the associations between systemic medication use and intraocular pressure (IOP) in the general population. OBJECTIVE: To examine the association between systemic medication use and IOP in a multiethnic Asian population. DESIGN, SETTING, AND PARTICIPANTS: In this post hoc analysis of the Singapore Epidemiology of Eye Diseases study, a population-based study of 10 033 participants (78.7% response rate) from 3 racial/ethnic groups (Chinese [recruited from February 9, 2009, through December 19, 2011], Malays [recruited from August 16, 2004, though July 10, 2006], and Indians [recruited from May 21, 2007, through December 29, 2009]), participants with glaucoma, previous ocular surgery, or trauma and an IOP asymmetry greater than 5 mm Hg between eyes were excluded. Intraocular pressure was measured using Goldmann applanation tonometry. An interviewer-administered questionnaire was conducted to collect data on medication and other variables. Data analysis was performed from August 1 through October 31, 2015. MAIN OUTCOMES AND MEASURES: Associations between medication and IOP were assessed using linear regression models adjusted for age, sex, body mass index, ethnicity, and the medical condition for which the medication was taken (angiotensin-converting enzyme inhibitors [ACEIs], angiotensin receptor blockers [ARBs], and ß-blockers adjusted for blood pressure, statins adjusted for lipids, and biguanides, sulfonylureas, α-glycosidase inhibitors [AGIs], and insulin adjusted for glycosylated hemoglobin). Medications associated with significant IOP differences were incorporated into regression models adjusted for concomitant use of multiple medications. Generalized estimating equation models were used to account for correlation between eyes. RESULTS: Of the 10 033 participants, we analyzed 8063 (mean [SD] age, 57.0 [9.6] years; 4107 female [50.9%]; 2680 Chinese [33.2%], 2757 Malay [34.2%], and 2626 Indian [32.6%] individuals). Systemic ß-blocker use was independently associated with an IOP of 0.45 mm Hg lower (95% CI, -0.65 to -0.25 mm Hg; P < .001). Conversely, higher mean IOP was associated with use of ACEIs (0.33 mm Hg higher; 95% CI, 0.08 to 0.57 mm Hg; P = .008), ARBs (0.40 mm Hg higher; 95% CI, 0.40-0.75 mm Hg; P = .02), statins (0.21 mm Hg higher; 95% CI, 0.02-0.4 mm Hg; P = .03), and sulfonylureas (0.34 mm Hg higher; 95% CI, 0.05-0.63 mm Hg; P = .02). An interaction between medication classes for additive, synergistic, or antagonistic effects on IOP was not identified. CONCLUSIONS AND RELEVANCE: Although systemic ß-blocker use was associated with lower IOP and systemic ACEI, ARB, statin, and sulfonylurea use was associated with higher IOP in this study, the associations were modest at best. Only the associations with systemic hypoglycemic agents were greater than 1 mm Hg, a threshold that has translated to a 14% greater risk of incident glaucoma across 5 years in other studies. At this point, the effect of systemic medication on IOP in eyes with glaucoma is not well elucidated but important. Our findings indicate that patients with glaucoma may potentially be at risk of higher or lower IOP, depending on medication class, and this would in turn affect management of IOP control.

Angiopoietin receptor TEK mutations underlie primary congenital glaucoma with variable expressivity.

Primary congenital glaucoma (PCG) is a devastating eye disease and an important cause of childhood blindness worldwide. In PCG, defects in the anterior chamber aqueous humor outflow structures of the eye result in elevated intraocular pressure (IOP); however, the genes and molecular mechanisms involved in the etiology of these defects have not been fully characterized. Previously, we observed PCG-like phenotypes in transgenic mice that lack functional angiopoietin-TEK signaling. Herein, we identified rare TEK variants in 10 of 189 unrelated PCG families and demonstrated that each mutation results in haploinsufficiency due to protein loss of function. Multiple cellular mechanisms were responsible for the loss of protein function resulting from individual TEK variants, including an absence of normal protein production, protein aggregate formation, enhanced proteasomal degradation, altered subcellular localization, and reduced responsiveness to ligand stimulation. Further, in mice, hemizygosity for Tek led to the formation of severely hypomorphic Schlemm's canal and trabecular meshwork, as well as elevated IOP, demonstrating that anterior chamber vascular development is sensitive to Tek gene dosage and the resulting decrease in angiopoietin-TEK signaling. Collectively, these results identify TEK mutations in patients with PCG that likely underlie disease and are transmitted in an autosomal dominant pattern with variable expressivity.

Sequencing analysis of the ATOH7 gene in individuals with optic nerve hypoplasia.

BACKGROUND: The Atonal Homolog 7 (ATOH7) gene has been implicated in association studies with optic nerve head diameter size. Hence, we screened optic nerve hypoplasia (ONH) patient DNA samples from Australia, France, and the United States for sequence variants in theATOH7 gene using Sanger sequencing. METHODS: Sanger sequencing of theATOH7 gene was performed on 34 affected individual DNA samples. Sequencing was also carried out in three unaffected family members to confirm segregation of identified single nucleotide variations. RESULTS: Seven sequence variations were identified in ATOH7. No disease-causing sequence changes in the ATOH7 gene was discovered in the ONH patient samples. CONCLUSIONS: Mutations within the ATOH7 gene are not implicated in the pathogenesis of optic nerve hypoplasia in our patient cohort.

CYP1B1, MYOC, and LTBP2 mutations in primary congenital glaucoma patients in the United States.

PURPOSE: To screen primary congenital glaucoma patients in the United States for sequence variants within the CYP1B1, LTBP2, and MYOC genes using Sanger and whole exome sequencing. DESIGN: Retrospective case-control study. METHODS: Fifty-seven primary congenital glaucoma patients (47 families), 71 unaffected family members of the primary congenital glaucoma probands, and 101 healthy unrelated individuals were recruited from a single institution. Sanger sequencing of the primary congenital glaucoma gene, CYP1B1, was performed on 47 proband deoxyribonucleic acid samples. Simultaneously, whole exome sequencing was conducted on 3 families, each including more than 1 affected individual. Concurrently, 33 of 47 primary congenital glaucoma probands with extended family deoxyribonucleic acid samples were screened for LTBP2 and MYOC gene mutations. Exome-sequenced variations were validated by additional Sanger sequencing to confirm segregation of filtered disease-causing single nucleotide variations. RESULTS: Seven primary congenital glaucoma families (14.9%) manifested disease phenotypes attributable to CYP1B1 mutations. One primary congenital glaucoma family possessed homozygous mutant alleles, whereas 6 families carried compound heterozygous mutations. Five novel combinations of compound heterozygous mutations were identified, of which 2 combinations were found with whole exome sequencing. No disease-causing mutations within the LTBP2 and MYOC genes were discovered. CONCLUSIONS: This study analyzed CYP1B1, LTBP2, and MYOC mutations in a cohort of primary congenital glaucoma patients from the United States, applying whole exome sequencing as a complementary tool to Sanger sequencing. Whole exome sequencing, coupled with Sanger sequencing, may identify novel genes in primary congenital glaucoma patients who have no mutations in known primary congenital glaucoma genes.

Study of a US cohort supports the role of ZNF644 and high-grade myopia susceptibility.

PURPOSE: Myopia, or nearsightedness, is highly prevalent in Asian countries and is considered a serious public health issue globally. High-grade myopia can predispose individuals to myopic maculopathy, premature cataracts, retinal detachment, and glaucoma. A recent study implicated zinc finger protein 644 isoform 1 (ZNF644) variants with non-syndromic high-grade myopia in a Chinese-Asian population. Herein we focused on investigating the role for ZNF644 variants in high-grade myopia in a United States (US) cohort. METHODS: DNA from a case cohort of 131 subject participants diagnosed with high-grade myopia was screened for ZNF644 variants. Spherical refractive error of -≤-6.00 diopters (D) in at least one eye was defined as affected. All coding, intron/exon boundaries were screened using Sanger sequencing. Single nucleotide allele frequencies were determined by screening 672 ethnically matched controls. RESULTS: Sequencing analysis did not detect previously reported mutations. However, our analysis identified 2 novel single nucleotide variants (c.725C>T, c.821A>T) in 2 high-grade myopia individuals- one Caucasian and one African American, respectively. These variants were not found in normal controls. A rare variant - dbsSNP132 (rs12117237→c.2119A>G) - with a minor allele frequency of 0.2% was present in 6 additional cases, but was also present in 5 controls. CONCLUSIONS: Our study has identified two novel variants in ZNF644 associated with high-grade myopia in a US cohort. Our results suggest that ZNF644 may play a role in myopia development.