High Prevalence of Asthenopia among a Population of University Students

Purpose: To determine the prevalence of asthenopia and its associated factors in a sample of university students in Iran. Methods: In this cross-sectional study, participants were selected using multistage cluster sampling. Presence of at least one of the 10 symptoms—foreign body sensation, diplopia, blurred vision, eye swelling, dry eye, eye pain, difficulty in sustaining visual operations, decreased visual acuity, tearing, and photophobia—was considered as asthenopia. Ocular examinations, including uncorrected/corrected visual acuity measurement, objective/subjective refraction, cover test, amplitude of accommodation (AA), and near point of convergence (NPC) were performed. Results: Of the 1,462 students (mean age: 22.8 ± 3.1 years), 73% were women. The age- and gender standardized prevalence was 70.9% (95% confidence interval [CI]: 68.3–73.5), 39.8% (95% CI: 36.4–43.1), and 19.7% (95% CI: 16.0–23.3) based on the presence of at least one, two, and three symptoms, respectively. The prevalence was significantly higher in females (P = 0.048), hyperopic students (P < 0.001), and astigmatic participants (P < 0.001). The mean AA and NPC were 9.7 ± 2.6 D and 10.2 ± 4.2 D (P = 0.008) and 7.0 ± 2.1 cm and 7.7 ± 3.9 cm (P < 0.001) in participants with and without asthenopia, respectively. Multiple regression model revealed age (28–29 years), astigmatism, and NPC as independent associated factors (odds ratios: 3.51, 1.61, and 0.91, respectively). Conclusion: This study shows relatively high prevalence of asthenopia in university students. Demographic factors and visual system disorders are important risk factors and timely correction of conditions may lead to decreased asthenopia

Near Points of Convergence and Accommodation in a Population of University Students in Iran

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

Does Long-Term Night Shift Work Cause Dry Eye in Hospital Nurses?

Purpose: To determine the long-term effects of night shift work on dry eye in hospital nurses. Methods: Each participant was evaluated four times, including at the beginning of the day shift (8 am), at the end of the day shift (2 pm), at the beginning of the night shift (8 pm), and at the end of the night shift (8 am), using the tear break-up time (TBUT) test and ocular surface disease index (OSDI) questionnaire. Results: The results showed significant differences in the TBUT and OSDI between the end of the day shift (2 pm) (10.26, 16.61) and the end of the night shift (8 am) (6.89, 38.59) relative to each other and relative to the beginning of the day and night shifts. As for the correlation between TBUT and OSDI, a significant correlation was found at all measurement times (correlation coefficient: −0.478, −0.707, −0.556, and −0.365, respectively) (p < 0.05). Conclusion: The results showed that the severity of dry eye increased after the night shift with variation over a 24-hr period. Moreover, a significant correlation was observed between TBUT and OSDI results at the beginning and at the end of the day and night shifts

Visual impairment and blindness in a population-based study of Mashhad, Iran

Purpose: To determine the prevalence of visual impairment and blindness and related factors in the 1- to 90-year-old urban population of Mashhad. Methods: In this cross-sectional study of 1- to 90-year-old residents of Mashhad, in northeastern Iran, sampling was done through random stratified cluster sampling (120 clusters). After selecting the samples and their participation in the study, all subjects had vision testing including measurement of visual acuity and refraction, as well as examinations with the slit-lamp and ophthalmoscopy. Visual impairment (primary outcomes) was defined as a visual acuity worse than of 0.5 logMAR (20/60) in the better eye. Results: Of the 4453 selected persons, 3132 (70.4%) participated in the study. The prevalence of visual impairment based on presenting vision and best-corrected vision was 3.95% (95% confidence interval [CI]: 3.13–4.77) and 2.23 (95% CI: 1.54–2.91), respectively. The prevalence of presenting visual impairment increased from 1.59% in children under 5 years of age to 43.59% in people older than 65 years of age; these figures were respectively 1.59% and 42.31% based on corrected visual acuity. In the logistic regression model, older age (OR = 1.06, 95% CI: 1.04–1.07, P < 0.001), higher education (OR = 0.16, 95% CI: 0.06–0.38, P < 0.001), and low income (OR = 1.36, 95% CI: 1.21–1.72, P < 0.001) correlated with impaired sight. Based on presenting vision and best-corrected vision, the prevalence of blindness was 0.86% (95% CI: 0.51–1.22) and 0.32% (95% CI: 0.1–0.55). The most common causes of visual impairment were uncorrected refractive error (41.8%) and cataract (20%). Conclusions: According to our findings, the prevalence of visual impairment was intermediate in comparison with other studies. The prevalence of visual impairment in our study was similar to the global average; however, it was markedly high at older ages. Nonetheless, refractive errors and cataracts remain as the main causes of impaired vision and blindness in this population, while these two conditions are easily treatable with correction or surgery. Keywords: Visual impairment, Blindness, Low-vision, Cross-sectional study, Middle-Eas

Comprehensive evaluation of dehydration impact on ocular tissue during Ramadan fasting

Purpose The present study aimed to review the effect of dehydration during Ramadan fasting on the health and ocular parameters leading to changes in eye function. Methods Articles included in the study were taken from PubMed, Ovid, Web of Science and Google Scholar up to 2014. Related articles were also obtained from scientific journals on fasting and vision system. Results Dehydration and nutrition changes in Ramadan cause an increase in tear osmolarity, ocular aberration, anterior chamber depth, IOL measurement, central corneal thickness, retinal and choroidal thicknesses, and also a decrease in IOP, tear secretion, and vitreous thickness. Conclusion Much research related to the effect of dehydration on ocular parameters during Ramadan fasting exists. The findings reveal association with significant changes on ocular parameters. Thus, it seems requisite to have a comprehensive study on "fasting and ocular parameters”, which will be helpful in making decisions and giving plan to the patients

The correlation between biomechanical properties of normal cornea with tomographic parameters of pentacam

Purpose: To investigate the correlation between corneal biomechanical properties and tomographic parameters of Pentacam. Methods: Corneal biomechanical properties and tomographic results of 36 normal subjects were measured by Ocular Response Analyzer (ORA) and Pentacam and the correlation between these two measurements were analyzed with Pearson correlation test with SPSS version16. Results: Significant correlation was found between corneal hysteresis (CH) and central corneal thickness (CCT), depth and angle of the anterior chamber, corneal shape factor and corneal volume (P0.05). Conclusion: Corneal thickness had an effective role in determining biomechanical properties of this tissue. In addition, significant correlation between CH and corneal volume was also found. Since corneal volume is a three dimensional parameter, it can play a more effective role than corneal thickness, the two dimensional parameter, in determining biomechanical properties of cornea.</p

Global and regional estimates of prevalence of refractive errors: Systematic review and meta-analysis

Purpose: The aim of the study was a systematic review of refractive errors across the world according to the WHO regions. Methods: To extract articles on the prevalence of refractive errors for this meta-analysis, international databases were searched from 1990 to 2016. The results of the retrieved studies were merged using a random effect model and reported as estimated pool prevalence (EPP) with 95% confidence interval (CI). Results: In children, the EPP of myopia, hyperopia, and astigmatism was 11.7% (95% CI: 10.5–13.0), 4.6% (95% CI: 3.9–5.2), and 14.9% (95% CI: 12.7–17.1), respectively. The EPP of myopia ranged from 4.9% (95% CI: 1.6–8.1) in South–East Asia to 18.2% (95% CI: 10.9–25.5) in the Western Pacific region, the EPP of hyperopia ranged from 2.2% (95% CI: 1.2–3.3) in South-East Asia to 14.3% (95% CI: 13.4–15.2) in the Americas, and the EPP of astigmatism ranged from 9.8% in South-East Asia to 27.2% in the Americas. In adults, the EPP of myopia, hyperopia, and astigmatism was 26.5% (95% CI: 23.4–29.6), 30.9% (95% CI: 26.2–35.6), and 40.4% (95% CI: 34.3–46.6), respectively. The EPP of myopia ranged from 16.2% (95% CI: 15.6–16.8) in the Americas to 32.9% (95% CI: 25.1–40.7) in South-East Asia, the EPP of hyperopia ranged from 23.1% (95% CI: 6.1%–40.2%) in Europe to 38.6% (95% CI: 22.4–54.8) in Africa and 37.2% (95% CI: 25.3–49) in the Americas, and the EPP of astigmatism ranged from 11.4% (95% CI: 2.1–20.7) in Africa to 45.6% (95% CI: 44.1–47.1) in the Americas and 44.8% (95% CI: 36.6–53.1) in South-East Asia. The results of meta-regression showed that the prevalence of myopia increased from 1993 (10.4%) to 2016 (34.2%) (P = 0.097). Conclusion: This report showed that astigmatism was the most common refractive errors in children and adults followed by hyperopia and myopia. The highest prevalence of myopia and astigmatism was seen in South-East Asian adults. The highest prevalence of hyperopia in children and adults was seen in the Americas

The prevalence and determinants of pterygium in rural areas

Purpose: To evaluate the prevalence of pterygium and its determinants in the underserved, rural population of Iran. Methods: In this cross-sectional study of 3851 selected individuals, 86.5% participated in the study, and the prevalence of pterygium was evaluated in 3312 participants. A number of villages were selected from the north and south of Iran using multistage cluster sampling. Pterygium was diagnosed by the ophthalmologist using slit-lamp examination. Results: The mean age of the study participants was 37.3 ± 21.4 years (2–93 years), and 56.3% (n = 1865) of them were women. The prevalence of pterygium was 13.11% [95%confidence interval (CI):11.75–14.47]. The prevalence of pterygium was 14.99 (95%CI:12.79–17.19) in men and 12.07 (95%CI:10.3–13.84) in women. Pterygium was not seen in children below the age of 5 years. The prevalence of pterygium increased linearly with age; the lowest and highest prevalence of pterygium was observed in the age group 5–20 years (0.19%) and 61–70 years (28.57%). Evaluation of the relationship between pterygium with age, sex, educational level, and place of living using a multiple model showed that age, living in the south of Iran, and low educational level were correlated with pterygium. Conclusion: The prevalence of pterygium was significantly higher in Iranian villages when compared with the results of previous studies. This finding may represent the effect of a rural lifestyle and its risk factors. Keywords: Pterygium, Prevalence, Rural population, Middle Eas

The prevalence of color vision deficiency in the northeast of Iran

Purpose: To determine the prevalence of color vision deficiency (CVD) in the northeast of Iran. Methods: This cross-sectional, population-based study was conducted in Mashhad, in the northeast of Iran. Multistage cluster sampling was used for selecting the participants. After preliminary screening, the subjects underwent a complete ophthalmic examination. The examination included the measurement of visual acuity, refraction, and slit-lamp biomicroscopy. The Farnsworth D-15 test was used to detect CVD. The color vision test was done with the best optical correction. Results: Of the 4453 invitees, 3132 participated in the study (response rate: 70.4%). The overall prevalence of CVD in this study was 13.93% [95% confidence interval (CI): 12.44–15.41]. The prevalence of CVD in males and females was 15.85% (95% CI: 13.26–18.44) and 12.96% (95% CI: 11.22–14.71), respectively. The most prevalent types of CVD were tritanopia (6.96%; 95% CI: 5.84–8.08), deuteranopia (3.92%; 95% CI: 3.14–4.70) and tritanomalous (2.21%; 95% CI: 1.55–2.86), respectively. According to the results of logistic regression, the odds of having protanopia were higher in females than males [Odds ratio (OR) = 4.80; 95% CI: 1.20–19.18]. The odds of having deuteranopia were lower in females than males (OR = 0.52; 95% CI: 0.35–0.76). The odds of having CVD were lower in 16–30 (OR = 0.52; 95% CI: 0.37–0.73) and higher in 46–60 (OR: 1.41; 95% CI: 1.01–1.97) year age groups compared to 7–15 year age group. The odds of having tritanopia in 16–30 and 46–60 year age groups was 0.56 (95% CI: 0.35–0.90) and 1.79 (95% CI: 1.19–2.67) compared to 7–15 year age groups, respectively. Conclusion: The prevalence of CVD was high in this study, especially in males and people over 46 years of age. Planning for involvement of ocular disease control programs in health care systems can be helpful in the reduction of CVD and improving the quality of life in affected patients. Keywords: Color vision deficiency, Prevalence, Population based study, Farnworth D-1

Anterior segment indices in mentally retarded children

Abstract To compare the anterior segment indices between mentally retarded and normal children. The current study was conducted as a cohort. In this study, 73 mentally retarded and 76 normal children were selected from normal school and special schools for mentally retarded children using random cluster sampling method. Mental retardation in children was confirmed by a psychologist. Optometry examinations including visual acuity and refraction were performed for all participants, and ultimately, corneal imaging measurements were taken by Pentacam. The mean age of mentally retarded and normal children was of 13.30 ± 1.83 and 13.05 ± 1.82 years, respectively (P = 0.180). A multiple generalized estimating equations model demonstrated that there is a significant association between central corneal thickness (CCT) (coef = 1.011, P < 0.001), corneal diameter (CD) (coef = 0.444, P = 0.046), anterior chamber depth (ACD) (coef = 0.23), P < 0.001) and index of vertical asymmetry (IVA) (coef = 0.12, P < 0.001) and mental retardation. Cerebral palsy children had higher keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry(IHA), and index of height decentration (IHD) compared to those without cerebral palsy (P < 0.05). Children with moderate mental retardation had higher index of surface variance (ISV), IVA, IHA, and IHD than those with mild mental retardation (P < 0.05). The mean and standard deviation of CCT, CD, ACD and IVA index in mentally retarded children were 535.3 ± 46.68 micron, 11.87 ± 0.42 mm, 3.29 ± 0.24 mm and 0.25 ± 0.18 mm, respectively. These indices in the normal group were 525.53 ± 47.52 micron, 11.84 ± 0.38 mm, 3.15 ± 0.28 mm and 0.17 ± 0.05 mm, respectively. The findings of this study showed that some anterior segment indices were different in mentally retarded compared to normal children. Moreover, some keratoconus indicators were worse in cerebral palsy children and children with higher grade mental retardation. So, it is important to consider keratoconus screening in these children