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The aim of this study was to produce a biosurfactant (rhamnolipid) from an autochthonousPseudomonas aeruginosaMM1011, which previously isolated from soil contaminated with crude oil over years. Produced biosurfactant subjected to different pressure 60–150 MPa, through high-pressure homogenization, for three cycles to produce nano-biosurfactant. Results showed that, homogenization was capable of producing nano-rhamnolipid (diameter as small as 631.4 nm). Homogenization pressure (about 90 MPa), were responding better than higher or lower pressures. Stability analysis supported a shelf life of up to one year at room temperature. This is the first report on stability of nano rhamnolipid using locally isolatedPseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Vacuum residue obtained from Tehran oil refinery vacuum distillation tower and used in a bubble column fermentor as the sole source of carbon and energy in minimal salts medium and different aeration applied. The best results for bacterial growth obtained at 0.08–0.3 v.v.m. Specific gravity of vacuum residue after biodegradation also decreased from 0.98 to 0.95. Decreasing specific gravity could be an indication for bio-lightening. Gas holdup was in the range of 0.007 to 0.062 and was well fitted with Hugmark correlation. [ABSTRACT FROM PUBLISHER]

The removal of hydrogen sulfide (H2S) from contaminated airstream was studied in a biotrickling filter (BTF) packed with open-pore polyurethane foam as a carrier of Thiobacillus thioparus (DSMZ5368) with counter current gas/liquid flows. The effect of operating parameters on BTF performance was studied. Experiments were performed at different Empty Bed Residence Times (EBRT) from 9 to 45 seconds, and different initial H2S concentration from 25 to 85 ppm. The results showed reasonable performance of the BTF, in H2S removal from the synthetic gas stream. However, the performance was somewhat lower than other studies in BTF in which either Thiobacillus thioparus with other packings or polyurethane foam with other microbial cultures were used. The effect of liquid recirculation rate (LRR) in the range of 175-525 ml/min (0.46-1.34 m/h) on BTF performance was also studied. Results showed that increasing LRR from 175 to 350 mL/min resulted in significant enhancement of H2S removal efficiency, but further increase in LRR up to 525 mL/min had an insignificant effect. H2S elimination at different heights of the bed was studied and it was found that decrease in EBRT results in more homogeneous removal of the pollutant in BTF. Determination of microbial species in the BTF after 100 days performance showed that during BTF operation the only H2S degrading specie was Thiobacillus thioparus. [ABSTRACT FROM AUTHOR]

Clinical Relevance: Distinguishing between the pathological thinning of the retinal nerve fibre layer (RNFL) and age-related reduction requires a comprehensive understanding of the longitudinal changes in RNFL thickness within a healthy population., Background: To determine five-year changes in RNFL thickness and associated factors in people aged 45-69 years., Methods: This report pertains to the second and third phases of the Shahroud Eye Cohort Study. Participants were recruited by a multi-stage cluster sampling in Shahroud, Iran. Data on demographic details, visual acuity, non-cycloplegic refraction, and slit-lamp biomicroscopy were collected. High-definition optical coherence tomography was employed for retinal imaging., Results: A total of 1,524 eyes from 908 participants were examined. The average RNFL thickness was 92.2 ± 8.5 (95% CI: 91.6 to 92.8) and 93.1 ± 8.7 μm (95% CI: 92.5 to 93.7) in the first and second phases with a five-year mean change of 0.95 ± 4.15 μm (95% CI: 0.70 to 1.20). The RNFL thickness mean changes in the superior, inferior, nasal, and temporal quadrants were 2.51 ± 7.86 (95% CI: 2.01 to 3.02), 2.93 ± 7.39 (95% CI: 2.56 to 3.29), -0.53 ± 6.15 (95% CI: -0.84 to -0.21), and -1.01 ± 4.67 μm (95% CI: -1.27 to -0.75), respectively. The five-year changes in average RNFL thickness were inversely correlated with axial length (β = -0.69, p  < 0.001), mean keratometry (β = -0.37, p  = 0.017), and baseline RNFL thickness (β = -0.617, p  < 0.001). In hyperopic individuals, the increase in average RNFL thickness (β = 0.65, p  = 0.012) was significantly greater than in those with emmetropia. Macular volume (β = 1.65, p  < 0.001) showed a direct association with five-year changes in average RNFL thickness., Conclusion: Over 5 years, RNFL thickness changes were clinically insignificant in the normal population. The mean RNFL thickness seems to remain stable unless there is ocular disease. However, increased axial length and steeper keratometric readings were linked to RNFL thinning. Those with thicker RNFL measurements were at higher risk of thinning over time.

Purpose: To determine the mean value and normative distribution of intraocular pressure (IOP) in children and their association with demographic and ocular biometrics., Methods: Cluster sampling was done to select the students in urban areas of Shahroud, northeast Iran, while all students living in rural areas were selected. IOP was measured in mmHg using a non-contact tonometer, along with corneal and retinal imaging and ocular biometric measurement., Results: After applying the exclusion criteria, 9154 eyes of 4580 students were analyzed, of whom 2377 (51.9 %) were boys. The mean age of the participants was 12.35±1.73 years (range: 9-15 years). The mean IOP was 15.58±2.83 (15.47-15.69) in total, 15.31±2.77 (15.17-15.46) in boys, and 15.88±2.86 (15.73-16.03) in girls (p < 0.001). The mean IOP was 15.07 and 15.49 in students aged 9 and 15 years, respectively. The mean IOP was 15.7 ± 2.64 (15.58-15.81) in urban and 14.52±4.05 (14.27-14.77) in rural students (p < 0.001). In the multiple generalized estimating equation model, IOP had a positive association with female sex (β=0.84, P < 0.001), systolic blood pressure (β=0.02, P < 0.001), cup volume (β=0.99, P < 0.001), corneal thickness (β=0.04, P < 0.001) and anterior chamber volume (β=0.007, P < 0.001) and a negative association with living in the rural area (β=-0.65, P < 0.001), rim area (β=-0.39, P < 0.001), and corneal diameter (β=-0.18, P = 0.045). Furthermore, individuals with myopia exhibited a significantly higher IOP (β=0.35, P < 0.001) compared to those with emmetropia., Conclusion: This study showed the normative distribution of IOP and its associated factors in children. The results can be used in diagnosis and management of glaucoma., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.)

Purpose: To determine the distribution of macular thickness and macular volume in an elderly healthy population 60 years of age and above and their determinants., Methods: The sampling was performed using a multistage stratified random cluster sampling method on the geriatric population 60 years of age and above in Tehran, Iran. All participants underwent optometric examinations, slit-lamp examination, and optical biometry. Retinal imaging was performed by spectral-domain optical coherence tomography., Results: The means ± standard deviation and 95% confidence interval of central macular thickness (CMT), average macular thickness (AMT), and macular volume were 221 ± 33 (218-223) μm, 267 ± 29 (265-269) μm, and 8.36 ± 0.44 (8.33-8.39) mm 3 , respectively. The CMT was significantly lower in females than males (β: -5.77; P = 0.002). The AMT was significantly lower in females than males (β = -10.32; P < 0.001) and was significantly directly related to intraocular pressure (β = 0.63; P = 0.038). The macular volume was significantly lower in females than males (β = -0.13; P < 0.001) and decreased with age (β = -0.01; P < 0.001). In addition, the macular volume had a significant inverse and direct relationship with axial length (β = -0.04; P = 0.011) and keratometry (β = 0.03; P < 0.001)., Conclusions: Macular thickness in the Iranian geriatric population was slightly less than the populations studied in other countries. The role of sex should also be taken into account in the interpretation of macular thickness findings., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Journal of Current Ophthalmology.)

Background: The aim of this study is to determine the 5-year changes in macular thickness and related factors., Methods: Data were from the second (2014) and third (2019) phases of the Shahroud Eye Cohort Study. Examinations included measurement of uncorrected and best-corrected visual acuity, non-cycloplegic autorefraction, slit-lamp biomicroscopy, and funduscopy. Participants underwent Cirrus HD-OCT 4000 (Carl Zeiss Meditec, Dublin, CA)., Results: The 5-year changes (95% confidence interval) of central and overall macular thicknesses were - 3.48 ± 8.16 μ (-3.92, -3.03) and - 0.79 ± 4.06 μ (-1.03, -0.54), respectively. The median and IQR of 5-year changes in the central subfield thickness were -3 and 10, although they were 0 and 5 in the overall macular thickness, respectively. Multiple regression model showed the central macular thickness (CMT) decreased with a U-shape pattern with increasing age. The 5-year changes in CMT were significantly lower in females compared to males β = -1.55; (-2.78, -0.32) and in smokers compared to non-smokers β = -1.92; (-3.55, -0.28). Moreover, higher body mass index β = -0.12; (-0.22, -0.02) and CMT at baseline β = -0.08; (-0.10, -0.06) were significantly associated with lower CMT changes. The average 5-year changes in overall macular thickness showed a non-linear decrease with age and was significantly higher in females β = 0.93; (0.4, 1.43). These changes were directly related to the anterior chamber depth β = 0.87; (0.10, 1.64) in the baseline., Conclusions: The macular thickness decreased slightly after 5 years; however, this change is not clinically significant. Demographic factors such as age and sex and refractive errors were significantly related to macular thickness changes., (© 2024 Royal Australian and New Zealand College of Ophthalmologists.)

The Proposed Specifier for Conduct Disorder (PSCD) was developed to measure the broad psychopathy construct with grandiose-manipulative, callous-unemotional, daring-impulsive, and conduct disorder subscales. This study tested the psychometric properties of Persian parent-and-child self-report PSCD versions with 974 parents (86% mothers) and children/adolescents (46.5% boys) dyads. Results showed that with some modifications the proposed hierarchical four-factor structure for both PSCDs was confirmed and was found to be invariant across gender. Across versions, all PSCD scores were internally consistent and demonstrated expected correlations with parent-reported externalizing problems, anxiety/depression, and poor school performance, supporting the PSCDs scores' validity. This study also is the first to examine and establish acceptable to excellent parent-child agreement of PSCD scores. Finally, all PSCD child-report scores offered small though significant incremental validity over their corresponding PSCD parent-version scores in predicting parent-reported conduct problems and proactive aggression. Findings indicated that both Persian PSCDs may hold promise for assessing psychopathy components in Iranian school-attending adolescents and generating additional research on this topic.

Aim: To determine the normative distribution of axial length (AL), anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and some of their associated factors in subjects aged 60 and over., Methods: In this cross-sectional study, 160 clusters were sampled using multi-stage cluster sampling in Tehran, Iran. After a preliminary interview, the participants underwent optometric examinations including visual acuity and refraction measurement followed by slit lamp biomicroscopy. Finally, ocular imaging was done using the Pentacam AXL to measure AL, ACD, ACV, and ACA., Results: A total of 4519 eyes of 2436 participants were evaluated, of whom 58.0% ( n =1412) were female. The mean age of the subjects was 67.32±6.05y (range: 60-95y). The mean AL, ACD, ACV, and ACA was 23.22 mm (23.18-23.27 mm), 2.61 mm (2.59-2.62 mm), 126.56 mm 3 (125.08-128.04 mm 3 ), and 30.61° (30.3°-30.92°), respectively. In the multivariable model, after adjusting for the effect of both eyes, the longest and shortest AL was seen in myopic and hyperopic subjects, respectively. AL, ACD, ACV and ACA were significantly larger in men compared to women ( P <0.001). Except ACA, other evaluated parameters showed an inverse correlation with age ( P <0.001), however, this correlation was insignificant for AL ( P =0.623)., Conclusion: Normative value of AL, and other biometric parameters are specific for each ethnicity, age and sex group. Any alteration in these parameters and their effect on refraction should be considered in this age group, especially in case of cataract surgery., (International Journal of Ophthalmology Press.)

Objectives: This study evaluated the relationship between acquired cataract's different types and the ABO and Rh blood classes., Methods: Overall, 520 patients, by randomized sampling method, participated in this retrospective cross-sectional study. After reviewing the patient's medical records and laboratory results, the patient's demographics, ABO group, Rh, and cataract type were documented., Results: A total of 520 patients were included in the research, with a mean age of 67.57 ± 11.85. Most of them were female (n = 286, 55%). Mix (n = 230, 44%) and nuclear sclerotic (NS) (n = 167, 32%) cataracts were the most common types. The posterior subcapsular cataract (PSC) prevalence in females was significantly higher than in males (16.1% vs.7.3% p = 0.002). Also, men had more NS cataracts than females (89, 38% vs. 78, 27.3%) (p = 0.009). Patients with PSC were significantly younger than others (all p-values < 0.001). Our results showed that cataract types are independent of blood group types and Rh (P > 0.05)., Conclusion: Although our findings showed that cataract types are independent of blood group types and Rh, they can be compared with future studies on the association of other Blood-Group Systems in developing acquired cataracts., (© 2023. BioMed Central Ltd., part of Springer Nature.)

An essential aspect of cancer registration is data quality. Data quality for Cancer Registries has been reviewed in this paper using four main criteria (comparability, validity, timeliness, and completeness). Medline (via PubMed), Scopus, and Web of Science databases were searched for relevant English articles published from inception until December 2022. Each study was analyzed for its characteristics, measurement method, and data quality features. According to the present study, the majority of articles evaluated the completeness feature, and the fewest evaluated the timeliness feature. A completeness rate of 36% to 99.3% and a timeliness rate of 9% to 98.5% were observed. Standardizing metrics and reporting of data quality is necessary to maintain confidence in the usefulness of cancer registries.

This scoping review aims to identify and summarize the current literature on Machine learning (ML) approaches for detecting coronary artery disease (CAD) using angiography imaging. We comprehensively searched several databases and identified 23 studies that met the inclusion criteria. They employed different types of angiography imaging including computed tomography and invasive coronary angiography. Several studies have used deep learning algorithms for image classification and segmentation, and our findings show that various machine learning algorithms, such as convolutional neural networks, different types of U-Net, and hybrid approaches. Studies also varied in the outcomes measured, identifying stenosis, and assessing the severity of CAD. ML approaches can improve the accuracy and efficiency of CAD detection by using angiography. The performance of the algorithms differed depending on the dataset used, algorithm employed, and features selected for analysis. Therefore, there is a need to develop ML tools that can be easily integrated into clinical practice to aid in the diagnosis and management of CAD.

Aim: To collect and present updated evidence about epidemiological aspects of retinoblastoma (Rb) in the world., Methods: A comprehensive search without the time and language restrictions was conducted in international databases, including MEDLINE, Scopus, Web of Science, and PubMed. The search keywords were "retinoblastoma" OR "retinal Neuroblastoma" OR "retinal glioma" OR "retinoblastoma eye cancer" OR "retinal glioblastoma"., Results: The worldwide incidence of Rb is 1 in 16 000-28 000 live births, but was higher in developing compared to developed countries. Several attempts for improving early detection and treatment had increased the Rb survival rate from 5% to 90% in developed countries over the past decade, but its survival was lower in developing countries (about 40% in low-income countries) and the majority of mortalities occurred in developing countries. The etiology of Rb could be viewed as genetics in the heritable form and environmental and lifestyle factors in the sporadic form. Some environmental risk factors such as in vitro fertilization; insect sprays; father's occupational exposure to oil mists in metal working, and poor living conditions might play a role in the occurrence of the disease. Although ethnicity might affect Rb incidence, sex has no documented effect and the best treatment approaches were now ophthalmic artery chemosurgery and intravitreal chemotherapy., Conclusion: Determining the role of genetics and environmental factors helps to accurately predict the prognosis and identify the mechanism of the disease, which can reduce the risk of tumor development., (International Journal of Ophthalmology Press.)

Research conducted on mobile apps providing mental health services has concluded that patients with mental disorders tend to use such apps to maintain mental health balance technology may help manage and monitor issues like bipolar disorder (BP). This study was conducted in four steps to identify the features of designing a mobile application for BP-affected patients including (1) a literature search, (2) analyzing existing mobile apps to examine their efficiency, (3) interviewing patients affected with BP to discover their needs, and 4) exploring the points of view of experts using a dynamic narrative survey. Literature search and mobile app analysis resulted in 45 features, which were later reduced to 30 after the experts were surveyed about the project. The features included the following: mood monitoring, sleep schedule, energy level evaluation, irritability, speech level, communication, sexual activity, self-confidence level, suicidal thoughts, guilt, concentration level, aggressiveness, anxiety, appetite, smoking or drug abuse, blood pressure, the patient's weight and the side effects of medication, reminders, mood data scales, diagrams or charts of the collected data, referring the collected data to a psychologist, educational information, sending feedbacks to patients using the application, and standard tests for mood assessment. The first phase of analysis should consider an expert and patient view survey, mood and medication tracking, as well as communication with other people in the same situation are the most features to be considered. The present study has identified the necessity of apps intended to manage and monitor bipolar patients to maximize efficiency and minimize relapse and side effects., Competing Interests: Conflict of InterestThe authors declare no competing interests., (© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Prcis: This study showed the distribution of optic disc indices in a population-based sample of Iranian children in detail. Refractive errors and biometric components are among the ocular factors that are related to these indices., Purpose: To determine the normative value of optic nerve indices in children and their association with ocular and demographic factors., Methods: A cross-sectional study was conducted in 2018. Biometry was done using the Allegro Biograph, and macular indices were measured by OCT imaging., Results: After applying the exclusion criteria, 9051 eyes of 4784 children were analyzed. The mean±SD and 95% confidence intervals (in parentheses) of vertical cup-to-disc ratio, average cup-to-disc ratio, rim area, disc area, and cup volume were 0.45±0.15(0.45-0.46) mm, 0.43±0.14 (0.42-0.43) mm, 1.46±0.25 (1.45-1.47) mm 2 , 1.92±0.35 (1.91-1.93) mm 2 , and 0.14±0.14 (0.14-0.15) mm 3 , respectively. Vertical cup-to-disc ratio and average cup-to-disc ratio had a positive association with intraocular pressure (IOP) (both βs=0.003), and a negative association with retinal nerve fiber layer thickness (both βs=-0.001), central corneal thickness (CCT) (both βs=-0.001), anterior chamber depth (β=-0.025 and β=-0.027, respectively), lens thickness (β=-0.034 and β=-0.032, respectively), and mean keratometry (MK) (both βs=-0.015). The average cup-to-disc ratio had a positive association with height (β=0.001). Rim area had a negative association with increased age (β=-0.008), axial length (β=-0.065), IOP (β=-0.009), and MK (β=-0.014) and a positive association with macular volume (β=0.021), retinal nerve fiber layer thickness (β=0.004), and CCT (β=0.001). Disc area had a positive association with macular volume (β=0.031) and a negative association with female sex (β=-0.037), axial length (β=-0.087), anterior chamber depth (β=-0.112), lens thickness (β=-0.059), and MK (β=-0.048). The results of generalized estimating equations showed that cup volume was smaller in girls (β=-0.009), and had a positive association with height (β=0.001), IOP (β=0.003) and negative association with CCT (β=-0.0001) and MK (β=-0.012)., Conclusion: The results provided the normative values of optic disc indices in children. Demographic factors, biometric components, IOP, SBP, and retinal parameters had a significant association with optic disc indices., Competing Interests: Disclosure: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Aim: To determine the distribution and associated factors of intraocular pressure (IOP) in an Iranian elderly population 60 years of age and above., Methods: The present report is part of the Tehran Geriatric Eye study (TGES), a population-based cross-sectional study that was conducted on the residents of Tehran 60 years of age and above. The sampling was performed using multistage stratified random cluster sampling methods from 22 districts of Tehran, Iran. Demographic and history information, blood samples, and blood pressure were collected from all participants. Ocular examinations included measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, and slit-lamp biomicroscopy. The IOP was measured using Goldmann applanation tonometry (GAT). Corneal imaging and ocular biometry were performed using Pentacam AXL., Results: The data of 3892 eyes of 2124 individuals were analyzed for this report. The mean age of the study participants was 66.49±5.31y (range: 60 to 95y). The mean IOP was 15.2 mm Hg (95%CI: 15.1 to 15.4), 15.3 mm Hg (95%CI: 15.1 to 15.5) and 15.1 mm Hg (95%CI: 15.0 to 15.3) in all participants, males, and females, respectively. Of the study participants, 1.3% had an IOP of ≥20 mm Hg. The mean IOP increased from 15.1 mm Hg in the age group 60-64y to 16.3 mm Hg in the age group ≥80y. According to the final multiple GEE model, the IOP was statistically significantly higher in men than in women. All the studied age groups, except for the 75-79-year-old age group, had significantly higher IOP compared to the 60-64-year-old age group. The IOP was significantly higher in underweight compared to other body mass index groups. Moreover, the IOP had a statistically significant direct relationship with the mean corneal power (mean CP), central corneal thickness (CCT), and systolic blood pressure., Conclusion: The present study presents the distribution of IOP in an Iranian elderly population. A higher IOP (within the range 14 to 17 mm Hg) is significantly associated with older age, male sex, high systolic blood pressure, increased mean CP, and CCT. These factors should be considered in the clinical interpretation of IOP., (International Journal of Ophthalmology Press.)

Objectives: This study aims to design a conceptual model for the effect of various factors on walking ability, participation, and quality of life in children with spastic diplegic cerebral palsy (SDCP) and test it based on field data using path analysis ., Materials & Methods: This cross-sectional study was performed on 181 children with SDCP. The following were used to measure each of the variables: the Modified Ashworth Scale, the Micro Manual Muscle Tester, the Timed Up and Go Test (TUG), the Boyd and Graham test, the goniometer, weight and height, the Gross Motor Function Classification System, the Life Habits Questionnaire, and cerebral palsy Quality of Life Questionnaire for Children. The structural model was tested in Amos 17., Results: All paths of the proposed model were significant (P <0.05). Among evaluated variables, muscle strength (B = -0.466), balance (B = 0.326), and spasticity (B = 0.143) affected walking ability. Moreover, as an intermediate factor, walking ability affected the subjects' participation (B = -0.819) and quality of life (B = -0.183)., Conclusion: Muscle strength, balance, and spasticity are the most influential factors in the walking ability of children with SDCP. Furthermore, walking ability and participation are two critical factors in promoting the quality of life of these children., Competing Interests: The authors declare that there is no conflict of interest.

Introduction: Silibinin is a natural flavonoid compound known to induce apoptosis in cancer cells. Despite silibinin's safety and efficacy as an anticancer drug, its effects on inducing immunogenic cell death (ICD) are largely unknown. Herein, we have evaluated the stimulating effects of silibinin on ICD in cancer cells treated with silibinin alone or in combination with chemotherapy. Methods: The anticancer effect of silibinin, alone or in combination with doxorubicin or oxaliplatin (OXP), was assessed using the MTT assay. Compusyn software was used to analyze the combination therapy data. Western blotting was conducted to examine the level of STAT3 activity. Flow cytometry was used to analyze calreticulin (CRT) and apoptosis. The heat shock protein (HSP70), high mobility group box protein1 (HMGB1), and IL-12 levels were assessed by ELISA. Results: Compared to the negative control groups, silibinin induced ICD in CT26 and B16F10 cells and significantly enhanced the induction of this type of cell death by doxorubicin, and these changes were allied with substantial increases in the level of damage-associated molecular patterns (DAMPs) including CRT, HSP70, and HMGB1. Furthermore, conditioned media from cancer cells exposed to silibinin and doxorubicin was found to stimulate IL-12 secretion in dendritic cells (DCs), suggesting the link of this treatment with the induction of Th1 response. Silibinin did not augment the ICD response induced by OXP. Conclusion: Our findings showed that silibinin can induce ICD and it potentiates the induction of this type of cell death induced by chemotherapy in cancer cells., (© 2023 The Author(s).)

Purpose: To compare visual evoked potential (VEP) components in normal individuals and those with long-term methamphetamine and crystal methamphetamine use., Methods: In this study, monocular pattern-reversal VEPs were recorded in 40 methamphetamine and crystal methamphetamine users and 38 normal individuals. Visual stimuli were high-contrast (99%) checkerboard patterns at 15 and 60 min of arc with a reversal rate of 1.53 reversals per second., Results: A significant difference was seen between the two groups for the P100 peak time for the 60 min of arc checks (p = 0.002, d = 0.75, 4.61% higher peak time in the addicted group) and the 15 min of arc checks (p = 0.004, d = 0.73, 4.78% higher peak time in the addicted group). However, other VEP components were not significantly different between the two groups., Conclusions: The higher P100 peak time at both 15 and 60 min of arc in methamphetamine-dependent users reveals that VEPs are highly sensitive for the diagnosis of retinal and visual pathway lesions., (© 2022 College of Optometrists.)

Clinical Relevance: Considering the significant relationship between methamphetamine abuse and some anterior segment indices, methamphetamine abuse should be considered in differential diagnosis especially in the case of angle closure glaucoma., Background: To investigate the effect of inhaled methamphetamine (meth) and crystal methamphetamine (crystal meth) on the quantitative indices of the cornea and anterior chamber using pentacam and anterior segment optical coherence tomography., Methods: In this cross-sectional study, the participants were (crystal) meth addicts living in Zahedan. The participants were transported to the examination site to undergo imaging and optometric tests. Pentacam and anterior segment optical coherence tomography imaging were then conducted so as to evaluate corneal and anterior chamber quantitative indices., Results: A total of 42 (crystal) meth addicts and 42 healthy subjects with matching age and gender were examined. Out of 42 subjects in the case group, 6 were female and 36 were male (mean age: 35.7 ± 8.6 years). The mean dose of drug used was 0.0074 ± 0.0034 g, and the mean duration of drug use was 6.9 ± 2.6 years (5-12 years). Based on the images of both devices, corneal curvature was significantly steeper in both meridians of anterior and posterior surfaces compared to the control group ( p = 0.01). Among the anterior chamber parameters, the anterior chamber depth and volume were lower in the cases than the controls ( p < 0.01). However, the lens rise was higher in addicts than controls ( p = 0.01)., Conclusion: Quantitative changes in corneal and anterior segment indices including dilated pupils, shallower anterior chamber depth and higher lens rise in addicted cases compared to the control group may precipitate the risk of closed-angle in these individuals.

Clinical Relevance: Accurate measurement of the anterior chamber depth is very important. There is no report regarding the agreement between rotating Scheimpflug imaging (Pentacam HR) and biograph (Lenstar LS 900) in children. This study therefore explores the agreement between Pentacam and Biograph in measuring anterior chamber depth in children., Background: This study aims to determine the agreement between Pentacam and Biograph in measuring anterior chamber depth in children., Methods: The participants were students living in urban and rural areas of Shahroud, Iran, selected through cluster sampling. The students were transported to the examination site to undergo imaging and optometric tests. Pentacam imaging was then conducted, and biograph was used to measure biometric components. In this report, the anterior chamber depth was calculated from the corneal endothelium., Results: Of 6624 students selected randomly, 5620 participated in the study. After applying the exclusion criteria, 4882 eyes were included in the final analysis. The mean anterior chamber depth measured by the Pentacam (3.09 ± 0.26 mm) was higher than that of biograph (3.04 ± 0.24 mm) (p < 0.001). The 95% limit of agreement (LOA) between the two devices was -0.19 to 0.09 mm. The variation of the difference between the two devices decreased, LOA became narrower, and the correlation coefficient of the devices increased with ageing. The highest intraclass correlation coefficient was seen among myopic (0.974) participants. The 95% LOA was -0.20 to 0.12 mm in hyperopic, -0.17 to 0.07 mm in myopic and -0.19 to 0.09 mm in emmetropic participants., Conclusion: The Pentacam and Biograph can be used interchangeably for measuring the anterior chamber depth in children.

Purpose: To determine the distribution of peripapillary retinal nerve fiber layer (RNFL) thickness and its association with different demographic and ocular parameters in adolescents., Methods: The present study is part of the second phase of the Shahroud Schoolchildren Eye cohort study, which was conducted in 2018 by reinviting the participants in the first phase. First, preliminary ocular examinations were performed, including measurement of uncorrected and best-corrected visual acuity, autorefraction, and subjective refraction.All study participants underwent corneal imaging using Pentacam to measure central corneal thickness and corneal radius of curvature (keratometry), ocular biometry using Allegro Biograph to measure anterior chamber depth, crystalline lens thickness, and axial length (AL), and finally optical coherence tomography imaging to measure RNFL thickness as well as macular thickness and volume., Results: The data of 4963 right eyes were analyzed after applying the exclusion criteria. The mean age of the study participants was 12.41±1.72 (9 to 15) years. The mean total, superior, inferior, temporal, and nasal RNFL thicknesses were 98.93 [95% confidence interval (CI): 98.61-99.25], 122.84 (95% CI: 122.31-123.37), 129.17 (95% CI: 128.63-129.7), 68.02 (95% CI: 67.65-68.38), and 75.69 (95% CI: 75.3-76.07), respectively. According to the results of the multivariable regression model, macular volume (β=9.81, P =0.001) had a significant direct association, and macular thickness (β=-0.01, P =0.046) had a significant inverse association with the average RNFL thickness. In addition, AL (β=-3.14, P <0.001), mean keratometry (β=-1.38, P <0.001), and central corneal thickness (β=-0.01, P =0.011) were significantly inversely related to the average RNFL thickness., Conclusion: We report the distribution of peripapillary RNFL thickness using spectral-domain optical coherence tomography and identify macular volume, AL, and mean keratometry as significantly associated factors in children. Our findings may serve as a database to interpret RNFL thickness results in children aged 9 to 15 years with suspected ocular disease., Competing Interests: Disclosure: The authors declare no conflict of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To determine the distribution of macular and cube thickness and their normal range in the students aged 9 years to 15 years and to investigate their associated demographic and biometric factors., Methods: This study was based on the data of the second phase of the Shahroud School Children Eye Cohort Study, conducted in 2018. After measurements of visual acuity, biometry, and subjective and cycloplegic refraction, retinal examination was performed using the Zeiss Cirrus HD 4000 optical coherence tomography., Results: The data of 5,043 right eyes were analyzed after applying the exclusion criteria. The central macular thickness was 239 ± 19.35 μ m. The mean cube volume and cube thickness were 9.94 ± 0.44 and 278 ± 12.20, respectively. According to multiple linear regression analysis, the central macular thickness was significantly lower in girls (coefficient [β]: -9.18; P < 0.001) and rural students (β: 3.86; P < 0.001) and had a direct association with axial length (β: 5.19; P < 0.001), lens thickness (β: 5.33; P = 0.003), and mean keratometry (β: 2.41; P < 0.001). The cube volume was lower in girls (β: -0.13; P < 0.001) and higher in rural students (β: 0.05; P < 0.001)., Conclusion: Macular thickness was slightly higher in Iranian children. Sex, living place, axial length, lens thickness, and mean keratometry were the main associated factors with macular thickness.

Purpose: Methamphetamine and crystal methamphetamine abusers were compared with healthy subjects using optical coherence tomography to assess their retinal nerve fiber layer, macula, and optic disk characteristics., Methods: Forty-one methamphetamine and crystal methamphetamine abusers and 42 healthy subjects (mean ± SD of age: 35.82 ± 8.6 and 37.76 ± 9.1 years, respectively) were incorporated in this cross-sectional study. The drug abusers had a history of at least five years of substance use through smoking. Fourier-domain optical coherence tomography was used to image and assess the characteristics of retinal nerve fiber layer, macular thickness, and optic disk in the study groups., Results: The retinal nerve fiber layer thickness was significantly lower in the superior and temporal retinal quadrants of drug abusers than healthy subjects (P = 0.008 and P = 0.028, respectively). This study did not find a significant difference between drug abusers and healthy controls regarding optic to disk ratio, rim area, and disk area (P > 0.05). The comparison between the study groups showed that the reductions in perifovea and the superior quadrant of parafoveal thickness were statistically significant (P < 0.001 and P = 0.029, respectively)., Conclusion: Fourier-domain optical coherence tomography measurements showed that the retinal nerve fiber layer and macular thickness were different between methamphetamine and crystal methamphetamine abusers and healthy subjects, which should be considered in clinical practice. It seems that these drug abuses can cause alterations in retinal morphology., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Aim: The current study was designed to provide detailed information on the prevalence of ocular abnormalities in patients with cerebral palsy (CP)., Methods: Four international online scientific databases, including Web of Science, PubMed, Scopus, and Google Scholar were systemically searched. First, the titles of the articles were evaluated, and if relevant, their abstracts and full texts were reviewed. The quality of the studies was assessed using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist., Results: A total of 147 articles were found in the initial search. After applying the exclusion criteria, 65 articles were chosen for further review, from which 17 articles, comprising a total of 1734 patients with CP ranging in age from birth to 22 years, passed the STROBE quality check and were included in this review. The prevalence of ocular abnormalities in the CP patients reported in the evaluated studies ranged between 34% to 100%, with refractive error, strabismus, and nystagmus exhibiting the greatest overall prevalence at 52%, 48%, and 11%, respectively in this population., Conclusion: Early ocular assessment of children with CP is essential for an accurate diagnosis, personalized rehabilitation and performing early interventions to improve their visual function.

Purpose: We conducted a systematic search to estimate DR prevalence in different age and gender groups, and to evaluate the determinants of heterogeneity in its prevalence., Methods: A systematic and comprehensive search from inception to August 10, 2020, was done in international databases, including Scopus, PubMed, Web of Science, Embase, and other data sources without any restriction to find cross-sectional studies related to the prevalence of DR., Results: Of 6399 studies, 90 articles with a sample size of 563460 individuals and 204189 diabetic patients were analyzed. The estimated pooled prevalence of DR in the diabetic population in general; in female and in male was 28.41% (95% CI: 25.98 to 30.84); 25.93% (95% CI: 23.54 to 28.31) and 28.95% (95% CI: 26.57 to 31.32); respectively and the prevalence of DR showed no inter-gender difference. The heterogeneity of the pooled prevalence according to I 2 was 99% ( p < .001). According to the meta-regression results, the variables of WHO region (Coefficient of AMRO vs SEARO: 15.56; p: 0.002), age (Coefficient of above 60 years vs below 40 year: 18.67; p: 0.001), type of DR (Coefficient: 19.01; p < .001), and publication year (Coefficient: -0.60; p: 0.001) had a significant correlation with heterogeneity., Conclusion: One third of diabetic patients suffered from DR, mostly NPDR. DR increased markedly after the age of 60 years, which could be due to the longer duration of diabetes. Age, WHO region, type of DR, and publication year affected the heterogeneity in the prevalence of DR.

Purpose: To compare on-axis measurements of the axial length (AL) with off-axis measurements in the paracentral horizontal and vertical positions using the Lenstar LS 900 biometer., Methods: In this, the samples were selected from patients scheduled for cataract surgery using a systematic randomization method. After applying the exclusion criteria, all subjects underwent optometric examinations and AL measurement using the Lenstar. Five consecutive, non-cycloplegic measurements were done on the right eye centrally, 10° temporally, 10° nasally, 10° superiorly and 10° inferiorly on the retina by the same examiner., Results: Two hundred and seven eyes were examined in this study, of which 126 (60%) were for female patients. The mean age of the participants was 64.32 ± 10.77 years (range: 34-91 years). The mean central, superior, inferior, temporal, and nasal axial AL was 23.22 ± 1.02, 23.21 ± 1.02, 23.21 ± 1.02, 23.21 ± 1.02, 23.20 ± 1.03, respectively. Comparison of these readings using repeated measures ANOVA showed a statistically significant difference in the AL value among these positions. According to the post-hoc results, superior and nasal AL was statistically significantly lower compared to the central AL., Conclusion: If on-axis biometry is not available, AL can be measured in an off-axis manner in the paracentral temporal, superior and inferior positions. Considering the marked difference in AL measurement between central and nasal positions, off-axis measurement is not recommended in the nasal part because it may be associated with a marked hyperopic shift after cataract surgery.

Purpose: To determine the age and sex-standardized prevalence and risk factors of anterior blepharitis in a geriatric population in "…"., Methods: This population-based study was conducted on the elderly population (over 60 years of age) of Tehran, the capital of "…" in 2019. Examinations included visual acuity assessment, refraction, and complete slit lamp examination. After the diagnosis of anterior blepharitis, its type (staphylococcal vs. seborrheic) was also determined. Multiple logistic regression was used to determine the risk factors of the disease., Results: 3310 individuals participated in this study. The data of 3284 participants were available for this report. The mean age of the participants was 68.6 ± 24.5 years, and (57.8 %) were female. Age and sex-standardized prevalence of anterior blepharitis was 33.5 % (95 % CI: 30.6-36.5%) of which 96.5 % were bilateral. The prevalence of seborrheic and staphylococcal types was 22.4 % (95 % CI: 19.9-25.2%) and 11.3 % (95 % CI: 9.2-13.5%), respectively. According to the multiple logistic regression, the prevalence of anterior blepharitis was positively related to age over 80 years (P < 0.001) and male gender (P < 0.001), and inversely related to education level (P = 0.033). No significant relationship was found between anterior blepharitis and other variables including systemic hypertension, diabetes mellitus, hyperlipidemia, smoking, socioeconomic status, and history of the previous eye examination. Sex had the greatest effect on developing anterior blepharitis (standardized coefficient: 0.325)., Conclusion: The results of this study showed a relatively high prevalence of anterior blepharitis in the elderly population which requires special attention of the health system to inform and control this disease through continuous training of the media and regional health centers., (Copyright © 2021 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To assess contrast sensitivity in clear and colored soft contact lenses under different lighting conditions., Methods: This study was performed on 34 medical students. Visual acuity was measured using a tumbling E chart at a distance of 6 m, and contrast sensitivity was determined by Pelli Robson chart at a distance of 1 m. These tests were repeated in mesopic (3 lux) and glare (2000 lux) conditions. Then, a clear contact lens was applied to one eye and a colored contact lens was applied to the other. After 2 hr, visual acuity and contrast sensitivity were measured for each individual. The results were compared with and without contact lenses under normal, mesopic, and glare conditions., Results: The mean refractive error was 0.44 ± 0.20 diopters. Repeated measures ANOVA showed a decline in contrast sensitivity with colored and clear contact lenses as compared to no-lens condition ( P < 0.001). Additionally, lighting conditions had a significant impact on contrast sensitivity ( P < 0.001); contrast sensitivity was lower in mesopic and glare conditions than under normal lighting condition., Conclusion: In addition to the drop in contrast sensitivity under unusual lighting conditions (e.g., glare and mesopic), wearing soft contact lenses can further reduce contrast sensitivity in different lighting conditions. Therefore, people who wear contact lenses should be aware of this reduction in visual performance in conditions like driving at night or in the fog., Competing Interests: The authors declare that they have no conflict of interest., (Copyright © 2021 Mahjoob et al.)

Purpose : To evaluate near point of convergence (NPC), near point of accommodation (NPA), and accommodative facility (AF) in order to determine their normative data in a rural population. Methods : The target population for this population-based, cross-sectional study was people living in rural areas. Each subject underwent extensive optometric and ophthalmic examinations, including the measurement of visual acuity, refraction, NPA, NPC, and AF. Results : The data of 1113 individuals was analyzed of whom 58.8% (n = 576) were women. The mean age of the participants was 15.26 ± 7.38 years (range: 6-30 years). The mean spherical equivalent of the subjects was 0.16 ± 0.63 D. The prevalence of myopia, hyperopia and astigmatism was 16.28% (13.97-18.58), 5.97% (4.49-7.44), 11.93% (9.91-13.95) in this study, respectively The mean and 95% confidence interval of NPC, NPA, and binocular accommodative facility (BAF) was 6.99 cm (6.84-7.15), 9.91 cm (9.71-10.11), and 9.84 cpm (9.63-10.06), respectively. A significant correlation was found between age and the parameters such that all evaluated parameters worsened significantly with age ( P < .001). Conclusion : The results of the present study showed the normal ranges of NPA, NPC, and BAF in a 6-30 year-old population living in rural areas of northern Iran. These parameters changed significantly with age.

Purpose: To determine the distribution of keratometry values in a wide age range of 6-90 years., Methods: In this cross-sectional study, samples were selected from two villages in Iran using multi-stage random cluster sampling. After completing optometry and ophthalmic examinations for all cases, corneal imaging was done using Pentacam, and keratometry values were determined., Results: Of the 3851 selected people, 3314 people participated in the study, and after applying the exclusion criteria, analyses were done on data from 2672 people. Mean age of the participants was 36.30 ± 18.51 years (from 6 to 90 years). Mean keratometry (mean-K) in flat and steep meridians was 42.98 (42.9-43.06) diopters (D) and 43.98 (43.91-44.07) D, respectively. Average of mean-K was 43.48 (43.41-43.56) D. Mean-K increased linearly up to the age of 70 years, and the cornea became slightly flat afterwards (coefficient = 0.01; P < 0.001). Mean-K was significantly higher in females ( P < 0.001). Myopic cases had the highest mean-K ( P < 0.001). The correlation of mean-K with age, gender, central corneal thickness, anterior chamber depth, pupil diameter, and spherical equivalent was investigated in a multiple regression model. Only older age and female gender showed a statistically significant association with mean-K. Overall, 31.62% (29.14-34.09) of the sample in this study had at least 1.0 D of corneal astigmatism., Conclusions: This is one of the few studies worldwide that demonstrates changes in keratometry in a wide age range from childhood to old age. Results indicated that age and gender are variables associated with keratometry., Competing Interests: There are no conflicts of interest., (Copyright: © 2021 Journal of Current Ophthalmology.)

Background: Mobile applications and social media serve their users as convenient tools to improve and monitor diseases and conditions such as pregnancy. These tools also exert a positive impact on Gestational diabetes mellitus (GDM) self-management., Introduction: Despite the expansion of mobile health apps for the management of GDM, no study has evaluated these apps using a valid tool. This study aimed to search and review the apps developed for this purpose, providing overall and specific rating scores for each aspect of MARS., Methods: Two cases of app stores (IOS and Google Play) were searched in January 2019 for apps related to GDM. Search keywords included "gestational diabetes", "pregnant diabetes", and "Health apps". Eligibility criteria include: capable of running on Android or IOS operating systems, in the English language, especially for GDM, and available in Iran. After removal of duplicates, the apps were reviewed, rated, and evaluated independently by two reviewers with Mobile App Rating Scale (MARS) tools., Results: Initially, 102 apps were identified after the exclusion process, five selected apps were downloaded and analyzed. All apps were classified into four categories according to contents and their interactive capabilities. In most quadrants of MARS, the Pregnant with Diabetes app received the highest scores. Also, in general, the maximum app quality mean score belonged to Pregnant with Diabetes (3.10 / 5.00)., Conclusion: Findings revealed that apps designed for GDM are small in number and poor in quality based on MARS tools. Therefore, considering pregnant women's need for using the capabilities of these apps in pregnancy management and promoting community-based care, it seems essential to develop and design a series of high-quality apps in all four specified categories (only giving comments, obtaining data and giving comments, diagnosis of GDM, and diet calculator)., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Purpose: To determine the distribution of keratoconus indices in a 5-93-year-old healthy eyes of a rural population in Iran., Methods: In this cross-sectional study, multi-stage cluster sampling was applied to select subjects from two villages in the north and southwest of Iran. After obtaining informed consent, all subjects underwent ophthalmologic and optometric examinations. Corneal imaging by the Pentacam was done in subjects above 5 years between 9 a.m. and 2 p.m., at least 3 h after wakeup. All subjects who had abnormal keratoconus indices were excluded. Our main outcome was keratometry-flat (K f ), keratometry-steep (K s ), keratoconus index (KI), and central keratoconus index (CKI)., Results: The mean ± standard deviation of K f , K s , KI, and CKI was 43.12 ± 1.74, 44.25 ± 1.65, 1.02 ± 0.02, and 1.01 ± 0.01, respectively. According to multiple linear regression analysis, the mean index surface variance (ISV) (b: -1.367, P < 0.001), index vertical asymmetry (IVA) (b: -0.012, P < 0.001), KI (b: -0.011, P < 0.001), CKI (b: -0.001, P < 0.001), index height asymmetry (IHA) (b: -0.491, P: 0.005), and index height decentration (IHD) (b: -0.001, P < 0.001) were lower in men compared to women. Moreover, age had an indirect association with ISV (b: -0.030, P < 0.001) and average pachymetric progression index (RPI&#95;avg) (b: -0.001, P < 0.001), and a direct association with KI, CKI, and IHA. Spherical equivalence had an indirect association with KI (b: -0.001, P < 0.001) and RPI&#95;avg (b: -0.004, P < 0.001) and a direct association with CKI (b: 0.001, P < 0.001). Among all variables, sex had the greatest impact on ISV, IVA, KI, IHA, IHD, and minimum sagittal curvature., Conclusions: The Keratoconus indices of our study were similar to other studies. Although age, living place, and type of refractive error were associated with some indices, sex was the strongest determinant of Keratoconus indices in a population of healthy eyes., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Journal of Current Ophthalmology.)

Purpose: To determine the distribution of residual and corneal astigmatism (CA) in children aged 6-18 years and their relationship with age, sex, spherical equivalent, and biometric parameters., Methods: In this cross-sectional study, multi-stage stratified cluster sampling was done to select students from Dezful, a city in Southwestern Iran. Examinations included the measurement of visual acuity with and without optical correction, refraction with and without cycloplegia, and biometry using the Biograph (Lenstar, Germany). The main outcomes in this report were corneal and residual astigmatism. The CA was measured by Biograph (difference between k1 and k2), and residual astigmatism was calculated using Alpine method. The power vector method was applied to analyze the data of astigmatism., Results: Of 864 students that were selected, 683 (79.1%) participated in the study. The mean residual and CA were -0.84 diopter (D) and -0.85 D, respectively. According to the results of J0 and J45 vectors, residual astigmatism was -0.33 D and 0.04 D, and CA was 0.38 D and 0.01 D, respectively. With-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism were seen in 3.4%, 66.8%, and 4.5% of the children with residual astigmatism and 67.94%, 1.3%, and 1.5% of the children with CA. Residual astigmatism decreased with an increase in spherical refractive error, whereas CA increased with an increase in spherical refractive error., Conclusion: The results of the present study showed a high prevalence and amount of residual astigmatism with ATR pattern among the 6-18-year-old population and the compensatory effect of this type of astigmatism on CA that mostly followed a WTR pattern., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Journal of Current Ophthalmology.)

Purpose: To review current non-surgical management methods of intermittent exotropia (IXT) which is one of the most common types of childhood-onset exotropia., Methods: A search strategy was developed using a combination of the words IXT, divergence excess, non-surgical management, observation, overcorrecting minus lens therapy, patch/occlusion therapy, orthoptics/binocular vision therapy, and prism therapy to identify all articles in four electronic databases (PubMed, Web of Science, Google Scholar, and Scopus). To find more articles and to ensure that the databases were thoroughly searched, the reference lists of the selected articles were also reviewed from inception to June 2018 with no restrictions and filters., Results: IXT is treated when binocular vision is impaired, or the patient is symptomatic. There are different surgical and non-surgical management strategies. Non-surgical treatment of IXT includes patch therapy, prism therapy, orthoptic sessions, and overcorrecting minus lens therapy. The objective of these treatments is to reduce the symptoms and the frequency of manifest deviation by decreasing the angle of deviation or enhancing the ability to control it., Conclusions: Evidence of the efficacy of non-surgical management options for IXT is not compelling. More comprehensive randomized controlled trial studies are required to evaluate the effectiveness of these procedures and detect the most effective strategy., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Journal of Current Ophthalmology.)

Aim: To investigate the heritability of corneal thickness at the apex, entrance pupil centre, thinnest point, pachymetric progression index (PPI) and maximum Ambrósio relational thickness (ART max ) using Pentacam., Methods: The present cross-sectional and population-based study was conducted in two rural districts that were selected randomly. Individuals 5 years and older and data from households where one of the parents and at least one child participated in the study were considered for this analysis. All subjects were examined for visual acuity, refraction, biomicroscopy and, finally, Pentacam imaging. The heritability estimate was used to calculate familial aggregation of pachymetric indices., Results: Of the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, a total of 1383 individuals from 382 households were included in the analysis; of these, 754 (54.52%) were female. The mean age of the subjects was 37.23±19.35 years (from 6 to 93 years). The highest heritability was observed for corneal thickness at the apex (85%), and the lowest was for ART max (27.62%). The heritability of other studied parameters, including corneal thickness at the entrance pupil centre, thinnest point and average PPI, was 82.0%, 77.0% and 31.49%, respectively., Conclusion: The high heritability of the mentioned pachymetric parameters confirms the high correlation between these phenotypes and genetic factors and calls for genetic and molecular research to find related genes and to understand the aetiology of associated diseases, especially glaucoma and keratoconus., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: To determine the distribution of keratoconus indices in normal children 6 to 12 years of age., Methods: This cross-sectional study was conducted in children living in urban and rural areas of Shahroud, northeast Iran in 2015. After careful optometric examinations, the Pentacam was used for corneal imaging and measurement of keratoconus indices., Results: Of 5,620 students who participated in the study, the data of the right eye of 4,947 children were analyzed after applying the exclusion criteria. The mean age of all children was 9.23±1.71 years (range: 6-12 years). The mean and 95% confidence intervals (in the parentheses) of index of surface variance (ISV), index of vertical asymmetry, keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry, index of height decentration (IHD), and average pachymetric progression index (PPIAve) was 17.770 (17.610-17.930), 0.137 (0.135-0.139), 1.022 (1.022-1.023), 1.010 (1.010-1.010), 3.299 (3.230-3.368), 0.007 (0.007-0.008), and 0.948 (0.943-0.952), respectively. The results of multilevel mixed-effects linear regression analysis showed that ISV, KI, CKI, IHD, and PPIAve were significantly higher in girls. Index of surface variance and CKI were higher in urban students, and PPIAve was higher in rural students. Except for PPIAve, which was increased with increasing age, the mean values of other keratoconus indices were significantly lower in 12-year-old students compared with 6-year-old ones., Conclusion: The results provide valuable information about normal distribution of keratoconus indices in children aged 6 to 12 years. These findings can be used in future research and detection of abnormal cases in the clinical setting.