Search

Background: Notwithstanding the encouraging results of previous studies reporting on the efficiency of deep learning (DL) in COVID-19 prognostication, clinical adoption of the developed methodology still needs to be improved. To overcome this limitation, we set out to predict the prognosis of a large multi-institutional cohort of patients with COVID-19 using a DL-based model., Purpose: This study aimed to evaluate the performance of deep privacy-preserving federated learning (DPFL) in predicting COVID-19 outcomes using chest CT images., Methods: After applying inclusion and exclusion criteria, 3055 patients from 19 centers, including 1599 alive and 1456 deceased, were enrolled in this study. Data from all centers were split (randomly with stratification respective to each center and class) into a training/validation set (70%/10%) and a hold-out test set (20%). For the DL model, feature extraction was performed on 2D slices, and averaging was performed at the final layer to construct a 3D model for each scan. The DensNet model was used for feature extraction. The model was developed using centralized and FL approaches. For FL, we employed DPFL approaches. Membership inference attack was also evaluated in the FL strategy. For model evaluation, different metrics were reported in the hold-out test sets. In addition, models trained in two scenarios, centralized and FL, were compared using the DeLong test for statistical differences., Results: The centralized model achieved an accuracy of 0.76, while the DPFL model had an accuracy of 0.75. Both the centralized and DPFL models achieved a specificity of 0.77. The centralized model achieved a sensitivity of 0.74, while the DPFL model had a sensitivity of 0.73. A mean AUC of 0.82 and 0.81 with 95% confidence intervals of (95% CI: 0.79-0.85) and (95% CI: 0.77-0.84) were achieved by the centralized model and the DPFL model, respectively. The DeLong test did not prove statistically significant differences between the two models (p-value = 0.98). The AUC values for the inference attacks fluctuate between 0.49 and 0.51, with an average of 0.50 ± 0.003 and 95% CI for the mean AUC of 0.500 to 0.501., Conclusion: The performance of the proposed model was comparable to centralized models while operating on large and heterogeneous multi-institutional datasets. In addition, the model was resistant to inference attacks, ensuring the privacy of shared data during the training process., (© 2024 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Purpose: To describe the prevalence of refractive error (RE) and its association with other environmental and health factors among population aged ≥50 years who lived in Gilan, Iran in 2014., Methods: In this population-based cross-sectional study, 3281 individuals aged ≥50 years living in Gilan for at least 6 months were enrolled. The prevalence of different types of REs including myopia (spherical equivalent (SE)≤-0.50D), high myopia (SE ≤ -6.00D), hyperopia (SE≥ + 0.50D), high hyperopia (SE≥ + 3.00D), astigmatism (cylinder < -0.50D) and high astigmatism (cylinder < -2.25D) were determined. Anisometropia was defined as the SE difference of ≥1.00D between the two eyes. Associated factors including age, body mass index (BMI) and education were also studied., Results: 2587 eligible individuals (58% female subjects) with the mean age of 62.6 ± 8.8 years participated (87.6% response rate). The prevalence of myopia, hyperopia and astigmatism was 19.2%, 48.6% and 57.4%, respectively. 3.6% high hyperopia, 0.5% high myopia and 4.5% high astigmatism were identified. The positive simultaneous effects3 of older age (Odds Ratio (OR) = 3.14), nuclear (OR = 1.71) and posterior subcapsular (OR = 1.61) cataracts as well as the negative effects of higher levels of education (OR = 0.28) were obtained on myopia. Higher BMI was found as a risk factor for hyperopia (OR = 1.67), while older patients were less likely to be hyperopic (OR = 0.31)., Conclusion: Higher incidence of myopia and astigmatism was found in patients aged over 70 years. It was also found that patients at older ages who suffered with cataracts were at a higher risk of myopia, while elderly people with greater BMI were at a higher risk of hyperopia., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: Extracting water equivalent diameter (DW), as a good descriptor of patient size, from the CT localizer before the spiral scan not only minimizes truncation errors due to the limited scan field-of-view but also enables prior size-specific dose estimation as well as scan protocol optimization. This study proposed a unified methodology to measure patient size, shape, and attenuation parameters from a 2D anterior-posterior localizer image using deep learning algorithms without the need for labor-intensive vendor-specific calibration procedures., Methods: 3D CT chest images and 2D localizers were collected for 4005 patients. A modified U-NET architecture was trained to predict the 3D CT images from their corresponding localizer scans. The algorithm was tested on 648 and 138 external cases with fixed and variable table height positions. To evaluate the performance of the prediction model, structural similarity index measure (SSIM), body area, body contour, Dice index, and water equivalent diameter (DW) were calculated and compared between the predicted 3D CT images and the ground truth (GT) images in a slicewise manner., Results: The average age of the patients included in this study (1827 male and 1554 female) was 53.8 ± 17.9 (18-120) years. The DW, tube current ,and CTDI vol measured on original axial images in the external 138 cases group were significantly larger than those of the external 648 cases (P < 0.05). The SSIM and Dice index calculated between the prediction and GT for body contour were 0.998 ± 0.001 and 0.950 ± 0.016, respectively. The average percentage error in the calculation of DW was 2.7 ± 3.5 %. The error in the DW calculation was more considerable in larger patients (p-value < 0.05)., Conclusions: We developed a model to predict the patient size, shape, and attenuation factors slice-by-slice prior to spiral scanning. The model exhibited remarkable robustness to table height variations. The estimated parameters are helpful for patient dose reduction and protocol optimization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: To determine the prevalence of cataract and its relationship with some determinants in individuals above 60 years., Methods: Of 3792 subjects that were invited, 3310 participated in the study (response rate = 87.31%). All subjects underwent full optometric, slit lamp, and fundoscopic examinations. Then, their lenses were evaluated according to the World Health Organization cataract grading system after pupil dilation., Results: Age- and sex-standardized prevalence with 95% confidence interval (CI) of nuclear, cortical, posterior subcapsular cataracts (PSC), any type cataract, and all lens change was 53.09% (49.80 to 56.35), 23.02% (20.87 to 25.32), 5.57% (4.62 to 6.70), 58.78% (55.65 to 61.83), and 72.49% (70.14 to 74.71), respectively. Any type, nuclear, cortical, and PSC cataracts, had a positive association with age and an inverse association with education. Moreover, the prevalence of cortical and PSC cataract had an inverse association with economic status. Among all variables, age was the strongest determinant for cataract and its subtype., Conclusion: This study found a higher prevalence of cataract compared to some previous studies such that about two-thirds of the geriatric population had cataract in the past or at the time of the study. Considering the association of cataract with variables such as economic status and education level, it seems that training and increased awareness and knowledge of the elderly population regarding the importance of eye care by physicians plays an important role in reducing the burden of cataract.

Background: We aimed to analyze the prognostic power of CT-based radiomics models using data of 14,339 COVID-19 patients., Methods: Whole lung segmentations were performed automatically using a deep learning-based model to extract 107 intensity and texture radiomics features. We used four feature selection algorithms and seven classifiers. We evaluated the models using ten different splitting and cross-validation strategies, including non-harmonized and ComBat-harmonized datasets. The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were reported., Results: In the test dataset (4,301) consisting of CT and/or RT-PCR positive cases, AUC, sensitivity, and specificity of 0.83 ± 0.01 (CI95%: 0.81-0.85), 0.81, and 0.72, respectively, were obtained by ANOVA feature selector + Random Forest (RF) classifier. Similar results were achieved in RT-PCR-only positive test sets (3,644). In ComBat harmonized dataset, Relief feature selector + RF classifier resulted in the highest performance of AUC, reaching 0.83 ± 0.01 (CI95%: 0.81-0.85), with a sensitivity and specificity of 0.77 and 0.74, respectively. ComBat harmonization did not depict statistically significant improvement compared to a non-harmonized dataset. In leave-one-center-out, the combination of ANOVA feature selector and RF classifier resulted in the highest performance., Conclusion: Lung CT radiomics features can be used for robust prognostic modeling of COVID-19. The predictive power of the proposed CT radiomics model is more reliable when using a large multicentric heterogeneous dataset, and may be used prospectively in clinical setting to manage COVID-19 patients., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: To determine the repeatability of corneal densitometry measured by the Scheimpflug imaging system., Methods: This cross-sectional study was conducted on photorefractive keratectomy candidates. One eye of each participant underwent imaging using Pentacam HR three times, 10 min apart. The repeatability of densitometry measurements was evaluated in four concentric annuli around the corneal apex and in different corneal depths. The repeatability of the measurements was evaluated using the intraclass correlation coefficient (ICC), repeatability coefficient (RC), and coefficient of variation (CV). The difference of repeatability between layers and zones was tested by tolerance index (TI)., Results: Sixty eyes of sixty patients with a mean age of 27.76 ± 3.93 years were studied. Half of the participants were female ( n = 30, 50%). ICC was above 0.9 in all corneal parts. The posterior layer and central zones showed the least variability of densitometry measurements considering the CV values. The RC was 2.06, 1.17, and 0.92 in anterior, central, and posterior layers, respectively. The RC was 0.88, 0.71, 1.51, and 4.56 in 0-2, 2-6, 6-10, and 10-12 mm circles, respectively. Only the reliability of densitometry in 10-12 mm annulus was statistically lower than the central zone (TI = 0.71)., Conclusions: Corneal densitometry measurements provided by the Pentacam had good repeatability. The repeatability of densitometry measurements decreased from the center to the periphery (with an exception for 0-2 mm and 2-6 mm) and from the posterior to the anterior of the cornea. The reliability of the 10-12 mm zone was markedly less than other zones., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Journal of Current Ophthalmology.)

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 the effect of duration of fluorometholone 0.1% treatment on corneal haze after photorefractive keratectomy (PRK) with mitomycin C (MMC) 0.02%., Design: Prospective, randomized, double-blind, clinical trial., Methods: Single-center clinical trial of 252 myopic PRK candidates (252 eyes) aged 21 to 40 years with a mean spherical equivalent (SE) of ≤ 6 diopters (D). Participants were randomized to receive one of the three corticosteroid regimens after PRK: Group A = 1 month followed by 2-month placebo; Group B = 2 months followed by 1-month placebo; and Group C = 3 months. The main outcome measures were corneal haze incidence, subjective SE, uncorrected distance visual acuity (UDVA), and corneal densitometry., Results: The corneal haze incidence (Grade ≥ 1) at 12 months was 1.35% (1/74 eyes) in Group A and 0% in the other two groups. The mean anterior corneal densitometry (grayscale unit) was 21.19 ± 2.07, 21.09 ± 2.19, and 21.31 ± 2.21 in Groups A, B and C, respectively. The mean SE was 0 ± 0.09, 0 ± 0.11, and 0 ± 0.10, and UDVA (decimal) was 1 ± 0, 1 ± 0.01, and 1 ± 0 in Groups A, B and C, respectively. During 1-year follow-up, no statistically significant difference was observed in mean SE (P = .158), UDVA (P = .343), and anterior corneal densitometry (P = .109) at any stage between the study groups., Conclusions: Long-term topical corticosteroids are unnecessary following PRK with MMC for moderate myopia., (Copyright © 2021 Elsevier Inc. All rights reserved.)

We present a deep learning (DL)-based automated whole lung and COVID-19 pneumonia infectious lesions (COLI-Net) detection and segmentation from chest computed tomography (CT) images. This multicenter/multiscanner study involved 2368 (347'259 2D slices) and 190 (17 341 2D slices) volumetric CT exams along with their corresponding manual segmentation of lungs and lesions, respectively. All images were cropped, resized, and the intensity values clipped and normalized. A residual network with non-square Dice loss function built upon TensorFlow was employed. The accuracy of lung and COVID-19 lesions segmentation was evaluated on an external reverse transcription-polymerase chain reaction positive COVID-19 dataset (7'333 2D slices) collected at five different centers. To evaluate the segmentation performance, we calculated different quantitative metrics, including radiomic features. The mean Dice coefficients were 0.98 ± 0.011 (95% CI, 0.98-0.99) and 0.91 ± 0.038 (95% CI, 0.90-0.91) for lung and lesions segmentation, respectively. The mean relative Hounsfield unit differences were 0.03 ± 0.84% (95% CI, -0.12 to 0.18) and -0.18 ± 3.4% (95% CI, -0.8 to 0.44) for the lung and lesions, respectively. The relative volume difference for lung and lesions were 0.38 ± 1.2% (95% CI, 0.16-0.59) and 0.81 ± 6.6% (95% CI, -0.39 to 2), respectively. Most radiomic features had a mean relative error less than 5% with the highest mean relative error achieved for the lung for the range first-order feature (-6.95%) and least axis length shape feature (8.68%) for lesions. We developed an automated DL-guided three-dimensional whole lung and infected regions segmentation in COVID-19 patients to provide fast, consistent, robust, and human error immune framework for lung and pneumonia lesion detection and quantification., Competing Interests: The authors declare no conflicts of interest., (© 2021 The Authors. International Journal of Imaging Systems and Technology published by Wiley Periodicals LLC.)

Background: To determine the distribution of the near point of convergence (NPC) and its related factors in an elderly population in Tehran, Iran., Methods: This population-based cross-sectional study was conducted on the elderly population (60 years of age and over) of Tehran, Iran in 2019. The samples were selected using stratified random cluster sampling. The examinations included the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, unilateral and alternate cover test, ocular health examination, and NPC measurement., Results: The mean age of the participants was 65.90 ± 4.56 years and 59.6% of them were females. The mean (95% CI) NPC in the total sample was 7.84 cm (95% CI: 7.65-8.03). The mean (95% CI) NPC in males and females was 7.92 cm (7.63-8.21) and 7.75 cm (7.54-7.97) (P = 0.338), respectively. The mean NPC increased from 7.8 cm (95% CI: 7.55-8.05) in the age group 60-64 years to 8.83 cm (95% CI: 7.47-10.2) in the age group ≥ 80 years (P > 0.05). The mean (95% CI) NPC in emmetropic, myopic, and hyperopic individuals was 7.67 cm (95% CI: 7.33-8.02), 7.96 cm (7.56-8.37), and 7.87 cm (7.63-8.11), respectively (P = 0.378). There was no statistically significant relationship between NPC with education level, smoking, diabetes mellitus (DM), and hypertension (HT)., Conclusions: The NPC values found in this study were significantly lower (less remote) than the values reported in previous studies in similar age groups. The NPC had no significant relationship with age, sex, education level, smoking, DM, and HT., (© 2021. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Background: Despite the prevalence of chest CT in the clinic, concerns about unoptimized protocols delivering high radiation doses to patients still remain. This study aimed to assess the additional radiation dose associated with overscanning in chest CT and to develop an automated deep learning-assisted scan range selection technique to reduce radiation dose to patients., Results: A significant overscanning range (31 ± 24) mm was observed in clinical setting for over 95% of the cases. The average Dice coefficient for lung segmentation was 0.96 and 0.97 for anterior-posterior (AP) and lateral projections, respectively. By considering the exact lung coverage as the ground truth, and AP and lateral projections as input, The DL-based approach resulted in errors of 0.08 ± 1.46 and - 1.5 ± 4.1 mm in superior and inferior directions, respectively. In contrast, the error on external scout views was - 0.7 ± 4.08 and 0.01 ± 14.97 mm for superior and inferior directions, respectively.The ED reduction achieved by automated scan range selection was 21% in the test group. The evaluation of a large multi-centric chest CT dataset revealed unnecessary ED of more than 2 mSv per scan and 67% increase in the thyroid absorbed dose., Conclusion: The proposed DL-based solution outperformed previous automatic methods with acceptable accuracy, even in complicated and challenging cases. The generizability of the model was demonstrated by fine-tuning the model on AP scout views and achieving acceptable results. The method can reduce the unoptimized dose to patients by exclunding unnecessary organs from field of view., (© 2021. The Author(s).)

Purpose: To determine the prevalence of Meibomian gland dysfunction (MGD) and its risk factors in an elderly Iranian population METHODS: This cross-sectional study was conducted in 2019. The target population was the subjects aged 60 and over living in Tehran. Multistage cluster sampling was done to select the subjects from all Tehran districts. After an initial interview, all subjects underwent complete ophthalmic examinations including the measurement of visual acuity and refraction as well as slit lamp biomicroscopy to evaluate Meibomian glands., Results: Of 3791 selected subjects, 3310 participated in the study. The data of 3284 participants were analyzed. The mean age of the subjects was 68.24 ± 6.53 years (range: 60-97 years) and 57.8% of them were female. The total prevalence of MGD was 71.2% (68.3-74.1), and 38.1% (8.35-40.4), 30.3% (27.4-33.2), and 2.8% (2-3.6) of the subjects had MGD stage 2, 3, and 4, respectively. The prevalence of MGD was significantly higher in men (p < 0.001) and increased with age from 64.4% in the age group 60-64 years to 82.4% in subjects aged 80 years and over. There was no significant difference in the prevalence of MGD between smokers and nonsmokers; however, severe MGD was more common in smokers. The prevalence of MGD was 76.3% and 68.52% in subjects with and without a history of ocular surgery, respectively. The prevalence of MGD stage 3 and 4 was higher in subjects with a history of ocular surgery., Conclusions: In line with the results of other studies in Asian countries, this study found a high prevalence of MGD in an elderly population of Iran. It was found that male gender and advanced age were risk factors of MGD and smoking and history of ocular surgery might worsen this disease in MGD patients.

Purpose: To describe the normative data of corneal densitometry in photorefractive Keratectomy (PRK) candidates by using a Scheimpflug camera., Methods: Five hundred twenty-two eyes of 261 PRK candidates that underwent comprehensive optometric and ophthalmic examinations were enrolled in this study. Corneal densitometry values were obtained using a Scheimpflug camera (Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany) and displayed in grayscale units (GSU)., Results: Of 261 participants, 187 (71.6%) were women. The mean age of the participants was 28.79 ± 5.02 years (range: 21-40 years). The mean entire corneal densitometry was 14.86 ± 2.37 GSU. According to corneal depth, maximum and minimum densitometry values were seen in the anterior (30.28 ± 7.42 GSU) and posterior (9.86 ± 2.08 GSU) layers, respectively (P < 0.001). Based on the annulus over the cornea, the highest and lowest densitometry values were seen in the 10- to 12-mm (21.31 ± 4.26 GSU) and 2- to 6-mm zones (13.26 ± 2.34 GSU), respectively. However, this difference was not seen after 35 years of age. Individuals aged 30 to 35 years showed higher corneal densitometry values compared with subjects aged 20 to 25 years old (P < 0.001). In generalized linear models, the corneal thickness was associated with the densitometry value in the central and posterior corneal layers. There were no significant differences in sex and refractive errors among participants., Conclusions: This study provided normal corneal densitometry data in PRK candidates. Corneal densitometry increased with age until 35 years of age and then decreased thereafter. This finding should be considered in patient selection for PRK and their postoperative examinations.

The aim of our study was to estimate regional and global cataract prevalence, its prevalence in different age groups, and the determinants of heterogeneity and its prevalence. For that, we used international databases such as PubMed, Web of Science, Scopus, Embase, and other sources of information to conduct a systematic search for all articles concerning the prevalence of age-related cataract and its types in different age groups. Of the 9922 identified articles, 45 studies with a sample size of 161,947 were included in the analysis, and most of them were from the Office for the Western Pacific Region (19 studies). Age- standardized pooled prevalence estimate (ASPPE) and 95% confidence interval (95% CI) of any cataract, cortical cataract, nuclear cataract, and posterior subcapsular (PSC) cataract were 17.20% (13.39-21.01), 8.05% (4.79-11.31), 8.22% (4.93-11.52), and 2.24% (1.41-3.07), respectively. Significant effects on heterogeneity were observed for the WHO region in the prevalence of any cataract (b: 6.30; p: 0.005) and study year in the prevalence of nuclear cataract (b: -0.66, p: 0.042). In general, the prevalence of cataract not only varies by region but also by age group, and most cases are over the age of 60 years. We examined the sources of variance in the prevalence of cataract and its different types, and identified age as a responsible factor in the prevalence of any cataract, cortical cataract, nuclear cataract, and PSC of cataract, WHO region in the prevalence of any cataract, and study year in the prevalence of nuclear cataract.

Purpose : To estimate the prevalence and associated factors of AMD in an Iranian population in 2014. Methods : In this population-based cross-sectional study, a total of 2975 Iranian residents (age: ≥50 years) from the urban and rural areas of Gilan province were included. The prevalence of different grades of AMD was determined using the International Age-Related Maculopathy Epidemiological Study Group grading system. Results : Of 2975 eligible individuals, 2587 (87.0%) subjects participated and 2275 (76.5%) subjects (62.6 ± 8.8 years old) had gradable fundus photographs. Age- and sex-standardized prevalence of early and late AMD based on the 2016 Iran census were 13.2% (95% confidence interval [CI], 10.6-16.2) and 0.7% (95% CI, 0.4-1.3), respectively. In multivariate analysis, each decade increase in age was associated with the adjusted odds of any (adjusted odds ratio [AOR] = 1.31, 95% CI, 1.09-1.56; P = .0031), early (AOR = 1.27, 95% CI, 1.06-1.53; P = .012) and late AMD (AOR = 2.39, 95% CI, 1.08-5.28; P = .031). Hyperopia was identified to be less frequent in late AMD (AOR = 0.20, 95% CI, 0.04-0.80; P = .024). No significant association was found between AMD and sex, smoking, outdoor working, diabetes, hypertension, pseudophakia, hyperlipidemia and myopia. Conclusion : Gilan Eye Study demonstrated the first estimate of age-specific AMD prevalence in Iran being compatible with other WHO regions. With the expected increase in the life expectancy and aging of Iranians, the number of people affected by AMD will be increasing in future. Healthcare policy makers should be advised to provide more efficient eye care services and preventive strategies in this regard.

Contradictory results of postoperative steroid application in photorefractive keratectomy (PRK) led to a meta-analysis of the existing data to achieve a definite conclusion on the optimum dosage and duration of corticosteroid therapy after PRK. The overall pooled unstandardized mean difference (PUMD) of the corneal haze score was -0.20 (95% CI, -0.29 to -0.12). In subgroup analysis, the PUMD of the corneal haze score was statistically significant in 2 subgroups, -0.57 (-0.85 to -0.30) for 3 to 6 months postoperatively and -0.13 (-0.23 to -0.04) for ≤ 3 months postoperatively. Analysis of the PUMD of postoperative spherical equivalent in participants with low to moderate myopia (≥-6.00 D) and high myopia (<-6.00 D) showed positive effects of steroids on prevention of myopia regression. In conclusion, long-term topical steroid application after PRK seems unnecessary in low and moderate myopia. New randomized clinical trials using current technologies are recommended for postoperative treatments.

Purpose : The aim of this study is to determine the prevalence of tropia, phoria, and their types in Islamic Azad University students in Shahrekord, Iran. Methods : Of 826 students that were invited, 752 participated in this cross-sectional study (response rate = 91.04%). After applying exclusion criteria, statistical analyses were performed on the data of 726 individuals. All participants underwent optometric tests including measurement of visual acuity, objective and subjective refraction, as well as binocular vision and ocular health examinations. The unilateral and alternate cover tests were done to detect the tropia and phoria at 6 m and 40 cm, respectively. Results : The overall prevalence and 95% confidence interval (CI) of tropia, exotropia, and esotropia were 1.5% (0.8 to 2.7), 1.2% (0.6 to 2.4), and 0.3% (0.1 to 1.1), respectively. The prevalence of esotropia was significantly higher in older age groups (24 years old) ( p = .040) . The prevalence of exotropia was significantly higher in females (0.039) and in myopic individuals ( p = .001). The overall prevalence and 95% CI of phoria, exophoria, and esophoria were 12.9% (10.7 to 15.6), 11.7% (9.6 to 14.3), and 1.2% (0.6 to 2.3), respectively. There was a significant difference in the overall prevalence of exophoria according to the age (0.021). The prevalence of esophoria was significantly higher in females ( p = .039). The prevalence of exophoria was significantly higher in myopic participants ( p = .003). Exophoria and exotropia were the most common types of phoria and tropia, respectively. Conclusion : The prevalence of strabismus in university students was similar to the Iranian general population but lower than other countries. One in every 10 students had phoria, which was much lower than similar reports on Iranian populations; however, due to near-work activity, these students are prone to asthenopia, early visual fatigue, and decreased productivity. Therefore, it is suggested that university students also undergo screening programs to detect the cases of tropia and phoria.

Purpose: To determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran., Methods: The subjects were selected using a cluster sampling method. All students underwent optometry tests, including visual acuity measurement, refraction, and cover test, as well as ophthalmic examinations. The NPC and NPA were measured using an accommodative target (near Snellen chart)., Results: Of 1,595 students, the data of 1,357 were analyzed. The mean NPC and NPA in the total sample were 7.25 cm (95% confidence interval [CI], 7.02 to 7.48) and 9.99 cm (95% CI, 9.69 to 10.29), respectively. Older age was associated with an increase in the NPC, which increased from 6.98 cm in 18-20 years olds to 9.51 cm in those over 30 years. The NPA was significantly associated with age and refractive errors in the multiple linear regression model, increasing from 9.92 cm in 18-20 years olds to 11.44 cm in those over 30 years ( P = 0.003). Hyperopic eyes had lower NPA than myopic and emmetropic eyes ( P = 0.001). In younger age groups, the mean accommodation amplitude was lower than the mean Hofstetter value. Moreover, with age, especially after 30 years, the mean values surpassed those determined using the Hofstetter formula., Conclusion: The NPC values in this study were lower than those previously reported for identical age groups. The Hofstetter formula is not always an accurate predictor of the accommodation amplitude in the Iranian adult population., Competing Interests: There are no conflicts of interest., (Copyright © 2019 Hashemi et al.)

Purpose : Despite the importance of information on the prevalence of strabismus, which can be effective in planning preventive and curative services, no study has addressed its prevalence comprehensively. In this study, a systematic search was done to estimate the regional and global prevalence of strabismus in different age and sex groups and factors affecting prevalence heterogeneity. Methods : A comprehensive and systematic search was done in different international databases, including Web of Science, Scopus, PubMed, Embase, etc. to find published articles on the total prevalence of strabismus and the prevalence of exotropia and esotropia. A binomial distribution was used to calculate the prevalence and 95% confidence interval (CI). The Cochran's Q-test and I 2 were applied to evaluate heterogeneity and a random-effects model was used to assess the pooled prevalence. The Begg's test was administered to investigate publication bias and finally, a meta-regression method was applied to determine the factors affecting the heterogeneity among studies. Results : Of 7980 articles, 56 articles with a total sample size of 229,396 were analyzed. Many of these articles (n = 14) were from the Regional Office for the Americas. The estimated of pooled prevalence (95% CI) of any strabismus, exotropia, and esotropia was 1.93% (1.64-2.21), 1.23% (1.00-1.46), and 0.77% (0.59-0.95), respectively. The heterogeneity in prevalence of strabismus and its subtypes according to I 2 was above 95% (p value <.001 for all). Age had a direct effect on heterogeneity in the prevalence of exotropia (b: 3.491; p: 0.002). Moreover, WHO region had a significant direct effect on heterogeneity in the prevalence of strabismus (b: 0.482; p < .001) and esotropia (b: 0.168; p: 0.027), and publication year had a significant direct effect on heterogeneity in the prevalence of exotropia (b: 0.059; p: 0.045). Sample size and publication year did not have any association with strabismus nor with other variables. There was no publication bias according to the Begg's test. Conclusion : The prevalence of strabismus varies widely in the world. As for factors affecting heterogeneity in the prevalence of strabismus, the results showed that age affected heterogeneity in the prevalence of exotropia, WHO region affected heterogeneity in the prevalence of strabismus and esotropia, and publication year affected heterogeneity in the prevalence of exotropia. Information about the global prevalence of strabismus can help health care planners design interventions and prioritize resource allocation.

Background : Amblyopia is one of the most important causes of vision impairment in the world, especially in children. Although its prevalence varies in different parts of the world, no study has evaluated its prevalence in different geographical regions comprehensively. The aim of the present study was to provide global and regional estimates of the prevalence of amblyopia in different age groups via a systematic search. Methods : In this study, international databases, including Embase, Scopus, PubMed, Web of Science, and other relevant databases, were searched systematically to find articles on the prevalence of amblyopia in different age groups published in English. The prevalence and 95% CI were calculated using binomial distribution. The Cochran's Q -test and I 2 statistic were applied to assess heterogeneity, a random-effects model was used to estimate the pooled prevalence, and a meta-regression method was utilized to investigate the factors affecting heterogeneity between studies. Results : Of 1252 studies, 73 studies were included in the analysis (sample volume: 530,252). Most of these studies ( n  = 25) were conducted in the WHO-Western Pacific Regional Office. The pooled prevalence estimate of amblyopia was 1.75% (95% CI: 1.62-1.88), with the highest estimate in European Regional Office (3.67%, 95% CI: 2.89-4.45) and the lowest in African Regional Office (0.51%, 95% CI: 0.24-0.78). The most common cause of amblyopia was anisometropia (61.64%). The I 2 heterogeneity was 98% ( p  < 0.001). According to the results of univariate meta-regression, the variables of WHO region ( b : 0.566, p  < 0.001), sample size ( b : -0.284 × 10 -4 , p : 0.025), and criteria for definition of amblyopia ( b : -0.292, p : 0.010) had a significant effect on heterogeneity between studies, while age group, publication date, and cause of amblyopia had no significant effect on heterogeneity. Conclusion : The prevalence of amblyopia varies in different parts of the world, with the highest prevalence in European countries. Geographical location and criteria for definition of amblyopia are among factors contributing to the difference across the world. The results of this study can help stakeholders to design health programs, especially health interventions and amblyopia screening programs.

Purpose: To provide the clinical recommendations for the administration of intravitreal anti-vascular endothelial growth factor (VEGF) drugs especially bavacizumab for ocular vascular diseases including diabetic macular edema, neovascular age-related macular degeneration, myopic choroidal neovascularization, retinal vein occlusion and central serous chorioretinopathy., Methods: Twenty clinical questions were developed by the guideline technical committee. Relevant websites and databases were searched to find out the pertinent clinical practice guidelines to answer the questions. The technical committee provided possible answers (scenarios) according to the available evidences for each question. All scenarios along with their levels of evidence and the supported articles were sent to the experts for external review. If the experts did not agree on any of the scenarios for one particular clinical question, the technical committee reviewed all scenarios and their pertinent evidences and made the necessary decision. After that, the experts were asked to score them again. All confirmed scenarios were gathered as the final recommendations., Results: All the experts agreed on at least one of the scenarios. The technical committee extracted the agreed scenario for each clinical question as the final recommendation. Finally, 56 recommendations were developed for the procedure of intravitreal anti-VEGF injection and their applications in the management of ocular vascular diseases., Conclusion: The implementation of this guideline can standardize the management of the common ocular vascular diseases by intravitreal injection of anti-VEGF agents. It can lead to better policy-making and evidence-based clinical decision by ophthalmologists and optimal evidence based eye care for patients., Competing Interests: There are no conflicts of interest.

Purpose: To develop clinical practice guidelines (CPGs) for prevention, diagnosis, treatment and follow-up of ocular injuries caused by exposure to mustard gas., Methods: The clinical questions were designed by the guideline team. Websites and databases including National Guidelines Clearinghouse, National Institute for Clinical Excellence, Cochrane, and PubMed were searched to find related CPGs and explore possible answers to the clinical questions. Since there were no relevant CPGs in the literature, related articles in Persian and English languages were extracted. Each article along with its level of evidence was summarized. Additionally, hand search was performed by looking the reference list of each article. Consequently, recommendations were developed considering the clinical benefits and side effects of each therapeutic modality. The recommendations were re-evaluated in terms of customization criteria. All recommendations along with the related evidence were scored from 1 to 9 by experts from all medical universities of Iran. The level of agreement among the experts was evaluated by analyzing the given scores., Results: The agreement was achieved for all recommendations. The experts suggested a number of minor modifications which were applied to the recommendations. Finally, CPGs were developed with 98 recommendations under three major domains including prevention of injury, diagnosis and management of the acute and delayed-onset mustard gas ocular injuries., Conclusion: Considering the lack of CPGs for the prevention, diagnosis, and management of mustard gas-induced keratitis, these recommendations would be useful to prevent the serious ocular complications of mustard gas and standardize eye care services to the affected individuals., Competing Interests: There are no conflicts of interest.

Purpose: To determine the prevalence and causes of blindness and visual impairment (VI) in Yazd, central Iran., Methods: This population-based, cross-sectional study was performed on adults aged 40-80 years, residing in Yazd district, in 2010-2011. Eligible subjects were selected using cluster random sampling. Each participant underwent an interview and complete ophthalmologic examination. Blindness and VI were defined as best-corrected visual acuity (VA) <3/60 and < 6/18 in the better eye, respectively., Results: Out of 2,320 eligible individuals, 2,098 participated in the study (90.4% response rate), of whom, 2,023 subjects completed all evaluations. The standardized prevalence of blindness and VI were 0.7% (95% confidence interval [CI], 0.3-1.0%) and 4.4% (95% CI, 3.3-5.4%), respectively which was significantly associated with older age (odd ratio [OR] = 3.2, 95% CI: 1.9-5.2 and OR = 3.1, 95% CI: 2.3-4.2, respectively) and female sex (OR = 3.6, 95% CI: 1.1-12.3 and OR = 1.7, 95% CI: 1.2-2.5, respectively). The proportion of avoidable causes of blindness and VI were 92.9% (95% CI: 80.0-100.0%) and 76.6% (95% CI: 69.2-85.0%), respectively. Major causes of blindness were diabetic retinopathy (50.0%), glaucoma (21.4%) and cataracts (14.3%) whereas main causes of VI were cataracts (41.5%), diabetic retinopathy (17.0%) and age-related macular degeneration (13.8%)., Conclusions: Diabetic retinopathy, glaucoma, cataract and age-related macular degeneration were the leading causes of blindness and VI in Yazd, most of which are avoidable. Planning for prevention of blindness is highly recommended to decrease the proportion of avoidable blindness.

Purpose: To determine agreement between peripapillary retinal nerve fiber layer (RNFL) thickness measurements by 2 spectral domain optical coherence tomography (SD-OCT) instruments.
, Methods: . This was an observational, cross-sectional study. Both eyes of 89 subjects, 44 healthy subjects (mean age, 47±15 years) and 45 patients with glaucoma (mean age, 55±14 years), were imaged using Cirrus OCT (Carl Zeiss Meditec, Inc. Dublin, CA, USA) and Topcon OCT (3D-OCT 1000, Topcon Corporation, Tokyo, Japan). One eye was randomly selected in each subject and peripapillary RNFL thickness measurements were compared. Bland-Altman plots were used to assess the level of agreement.
, Results: . Average peripapillary RNFL thickness measurements were significantly larger with Topcon OCT compared to Cirrus OCT in normal (101±12 vs 91±8 µm, p<0.001) and glaucomatous eyes (89±18 vs 76±16 µm, p<0.001). The limits of agreement for average peripapillary RNFL thickness measurements were poor, (-11 to 32 µm) in normal and (-4 to 30 µm) in glaucomatous eyes.
, Conclusions: . Peripapillary RNFL thickness values obtained by Topcon OCT are significantly higher than those measured by Cirrus OCT in both normal and glaucomatous eyes. Clinicians should be aware of this discrepancy especially when monitoring patients imaged by different OCT instruments; measured values cannot be used interchangeably.