Prevalence of refractive errors in Iranian university students in Kazerun

Purpose: To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with different types of refractive errors in a population of university students in the south of Iran. Methods: In this cross-sectional study, a number of university majors were selected as clusters using multi-stage sampling in all universities located in Kazerun (27 clusters of 133 clusters). Then, proportional to size, a number of students in each major were randomly selected to participate in the study. Uncorrected and corrected visual acuity, non-cycloplegic objective refraction and subjective refraction were measured in all participants. Results: The prevalence and 95 confidence interval (CI) of presenting visual impairment and blindness was 2.19 (1.48-3.23) and 0.27 (0.12-0.62), respectively. Refractive errors comprised 75 of the causes of visual impairment. The prevalence (95 CI) of myopia spherical equivalent (SE) = 0.5 D), and astigmatism (cylinder power = 30 years was 0.21 (95% CI: 0.04-0.98). Conclusions: The prevalence of refractive errors, especially myopia, is higher in university students than the general population. Since refractive errors constitute a major part of visual impairment, university students should receive special services for providing corrective lenses and glasses to reduce the burden of these disorders

Objective and subjective assessing efficacy of a lubricating drop in eyes wearing silicone hydrogel contact lenses

Purpose: To investigate the effect of a lubricating drop on optical quality, tear film stability, and subjective symptoms in individuals wearing silicone hydrogel contact lens. Methods: In this one-day, prospective single-center clinical study, Pre-lens Tear Deformation Time (PL-TDT), Root-Mean-Square (RMS) of Low Order Aberrations (LOA) and High Order Aberrations (HOA), individual twelve Zernike coefficients, and subjective symptoms were assessed in 43 volunteers (mean age 19.58 ± 1.63, 86 eyes) at 6 h after inserting the contact lens and then at 60 min after instilling a lubricating drop (Comfort drops, Avizor, Madrid-Spain). Results: PL-TDT, LOA-RMS, and HOA-RMS values measured before drop instillation were not significantly different with those measured after drop. None of the Zernike coefficients were significantly different after instilling lubricating drop. Statistically significant decrement in both frequency and severity values in blurry vision, dryness, discomfort, burning, itching, foreign body sensation, excessive blinking, and lacrimation were seen after drop instillation (all P < 0.05). Conclusion: Our results showed that although the lubricating drop did not improve the tear film stability and optical quality in the silicone hydrogel contact lens wearers, subjects experienced a subjective improvement. © 2016 Iranian Society of Ophthalmology

The prevalence of color vision deficiency in 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 (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. © 2017 Iranian Society of Ophthalmology

Enantiomorphism and rule similarity in the astigmatism axes of fellow eyes: A population-based study Enantiomorfismo y similitud de la regla en los ejes del astigmatismo en ojos contralaterales: estudio poblacional

Purpose: To evaluate the relationship patterns between astigmatism axes of fellow eyes (rule similarity and symmetry) and to determine the prevalence of each pattern in the studied population. Methods: This population-based study was conducted in 2015 in Iran. All participants had tests for visual acuity, objective refraction, subjective refraction (if cooperative), and assessment of eye health at the slit-lamp. Axis symmetry was based on two different patterns: direct (equal axes) and mirror (mirror image symmetry) or enantiomorphism. Bilateral astigmatism was classified as isorule if fellow eyes had the same orientation (e.g. both eyes were with-the-rule) and as anisorule if otherwise. Results: Of the total cases of bilateral astigmatism, 80 were isorule, and in the studied population, the prevalence of isorule and anisorule astigmatism was 14.89 and 3.53, respectively. The prevalence of isorule increased with age (p 0.288). Both symmetry patterns reduced with age (p < 0.001). Among cases of bilateral astigmatism, 15.5 and 19.8 had exact direct and mirror symmetry, respectively. Conclusion: Bilateral astigmatism is mainly isorule in the population and anisorule astigmatism is rare. The enantiomorphism is the most common pattern in the population of bilateral astigmatism. © 2018 Spanish General Council of Optometr

Enantiomorphism and rule similarity in the astigmatism axes of fellow eyes: A population-based study Enantiomorfismo y similitud de la regla en los ejes del astigmatismo en ojos contralaterales: estudio poblacional

Purpose: To evaluate the relationship patterns between astigmatism axes of fellow eyes (rule similarity and symmetry) and to determine the prevalence of each pattern in the studied population. Methods: This population-based study was conducted in 2015 in Iran. All participants had tests for visual acuity, objective refraction, subjective refraction (if cooperative), and assessment of eye health at the slit-lamp. Axis symmetry was based on two different patterns: direct (equal axes) and mirror (mirror image symmetry) or enantiomorphism. Bilateral astigmatism was classified as isorule if fellow eyes had the same orientation (e.g. both eyes were with-the-rule) and as anisorule if otherwise. Results: Of the total cases of bilateral astigmatism, 80 were isorule, and in the studied population, the prevalence of isorule and anisorule astigmatism was 14.89 and 3.53, respectively. The prevalence of isorule increased with age (p 0.288). Both symmetry patterns reduced with age (p < 0.001). Among cases of bilateral astigmatism, 15.5 and 19.8 had exact direct and mirror symmetry, respectively. Conclusion: Bilateral astigmatism is mainly isorule in the population and anisorule astigmatism is rare. The enantiomorphism is the most common pattern in the population of bilateral astigmatism. © 2018 Spanish General Council of Optometr

Enantiomorphism and rule similarity in the astigmatism axes of fellow eyes: A population-based study Enantiomorfismo y similitud de la regla en los ejes del astigmatismo en ojos contralaterales: estudio poblacional

Purpose: To evaluate the relationship patterns between astigmatism axes of fellow eyes (rule similarity and symmetry) and to determine the prevalence of each pattern in the studied population. Methods: This population-based study was conducted in 2015 in Iran. All participants had tests for visual acuity, objective refraction, subjective refraction (if cooperative), and assessment of eye health at the slit-lamp. Axis symmetry was based on two different patterns: direct (equal axes) and mirror (mirror image symmetry) or enantiomorphism. Bilateral astigmatism was classified as isorule if fellow eyes had the same orientation (e.g. both eyes were with-the-rule) and as anisorule if otherwise. Results: Of the total cases of bilateral astigmatism, 80 were isorule, and in the studied population, the prevalence of isorule and anisorule astigmatism was 14.89 and 3.53, respectively. The prevalence of isorule increased with age (p 0.288). Both symmetry patterns reduced with age (p < 0.001). Among cases of bilateral astigmatism, 15.5 and 19.8 had exact direct and mirror symmetry, respectively. Conclusion: Bilateral astigmatism is mainly isorule in the population and anisorule astigmatism is rare. The enantiomorphism is the most common pattern in the population of bilateral astigmatism. © 2018 Spanish General Council of Optometr

The distribution of ocular biometry in Iranian school children

Purpose: To determine the distribution of axial length (AL), vitreous chamber depth (VCD), anterior chamber depth (ACD), lens thickness (LT), lens power (LP), radius of curvature (CR), and white-to-white corneal diameter (WTW) in the 14-20 year age range. Methods: In a cross-sectional study, sampling was done from Aligoodarz high schools using multistage simple cluster sampling. For all students, visual acuity and non-cycloplegic refraction tests were performed. Biometric components were measured using Allegro Biograph (WaveLight AG, Erlangen, Germany). Results: In this report, data from 434 cases was used in the analysis; of these 222 (51.2) were females. Mean and 95 confidence intervals of AL, VCD, ACD, LT, LP, CR, and WTW in the studied sample were 23.4 mm (23.32 to 23.48), 16.82 mm (16.74 to 16.9), 3.14 mm (3.12 to 3.16), 3.44 mm (3.42 to 3.46), 22.65 diopter (22.47 to 22.83), 7.74 mm (7.72 to 7.76), and 12.26 mm (12.22 to 12.3), respectively. In the multiple regression model, AL, VCD, ACD, CR, and WTW was significantly higher in boys while mean LT and LP were significantly higher in girls. The distributions of AL, ACD, LT, and CR were significantly different from normal. The distributions of AL, LT, and CR were leptokurtic, unlike ACD which had a platykurtic distribution pattern. Conclusion: In this report, we describe the normal ranges of ocular biometric components in a sample population of 14-20 year old Iranians. ACD in this study was shorter and WTW was larger than previous studies and other components were in the midrange. More studies throughout Iran are needed to verify a shorter ACD and larger WTW. All components of ocular biometry showed significant inter-gender differences. © 2014 by the Iranian Society of Ophthalmology

The prevalence of ptosis and nystagmus in rural population

Purpose: To determine the prevalence of ptosis and nystagmus in the general rural population in Iran. Methods: Two villages were selected from the north and southwest of Iran using a multi-stage cluster sampling approach. After selection of the participants and inviting them to a complete eye exam, they all had vision tests and an ophthalmic examination. Vision tests included measurement of visual acuity, refraction, and the cover test. Then the slit-lamp exam was performed, and the diagnosis of ptosis and nystagmus was determined by an ophthalmologist. Results: Of the 3851 invitees, 3314 people participated in the study. The prevalence of ptosis in this study was 2.23 95% confidence interval (CI): 1.73-2.74, and 45.3% of the cases were bilateral ptosis. The prevalence of ptosis was lowest in the 21-30 year (0.2%) and the under 5 year (0.8%) age groups, and the highest prevalence was observed in people over 70 years of age (6.7%) (P < 0.001). The prevalence of ptosis was higher in illiterate people than those with an academic education level (P = 0.012). The prevalence of astigmatism was 62.8% in those with ptosis and 34.2% in those without ptosis (P < 0.001). The prevalence of nystagmus was 0.39% (13 cases). Conclusions: This study found that the prevalence of ptosis is relatively high in the general rural population in Iran, and the prevalence increases with age. Astigmatism is significantly high among cases with ptosis, and its prevalence has an inverse relation with the level of education. Nystagmus also had a high prevalence in this population. © 2020 Journal of Current Ophthalmology | Published by Wolters Kluwer-Medknow

Economic inequality in unmet refractive error need in deprived rural population of Iran

Purpose: To determine economic inequality in unmet refractive error (RE) need and its determinants in deprived rural population of Iran. Methods: In this population-based study, two villages were randomly selected from among underserved villages of Iran. After selecting the participants, optometric examinations, including uncorrected and corrected visual acuity and subjective and manifest refraction, were done for all the participants. Then, unmet need for glasses was determined. Concentration index (C) was used to assess inequality, and Oaxaca-Blinder decomposition method was applied to decompose the gap between the two groups based on the determinants. Results: Of 3851 samples, 3314 participated in the study (response rate = 86.05). The data of 3255 participants were used for analysis. The value of C and 95 confidence interval (CI) was-0.088 (-0.157 to-0.020), indicating a pro-poor inequality in unmet need. The prevalence (95 CI) of unmet need was 11.74 (9.25-14.22) in the poor and 6.51 (4.96-8.06) in the rich, with a gap of about 5 in favor of the rich (P < 0.001). A marked percentage of the gap was due to the explained portion (b = 5.73; P = 0.031). In the explained portion, the variable of economic status (b = 3.48; P = 0.004) and myopia (b = 0.88; P = 0.031) caused inequality in favor of the rich and against the poor, respectively. In the unexplained portion (b =-0.51; P = 0.372), the variables of education (P = 0.002) and place (P = 0.001) had statistically significant effects on inequality. Conclusions: There is a significant pro-poor economic inequality in the prevalence of unmet need in rural areas of Iran. Although part of this inequality is related to variables such as education and myopia, a major portion (two thirds) of this inequality may be due to the direct effect of economic inequality. © 2020 Journal of Current Ophthalmology | Published by Wolters Kluwer-Medknow

The distribution of near point of convergence in an Iranian rural population: A population-based cross-sectional study

Objective: To determine the distribution of near point of convergence (NPC) according to age, sex, and refractive error in a rural population above 1 year of age in 2015. Methods: In this population-based cross-sectional study, multistage cluster sampling was applied to randomly select two underserved areas from the north and southwest of Iran and all individuals above 1 year living in these areas were invited to participate in the study. All participants underwent ocular examinations including visual acuity measurement, refraction, binocular vision testing including cover test and measurement of NPC, and slit lamp biomicroscopy. Results: Of 3851 who were invited, 3314 participated in the study (response rate: 86.5). The NPC was 8.42 ± 2.94 cm in the whole population, 8.59 ± 3.07 cm in men, and 8.30 ± 2.84 cm in women. Subjects above 70 years of age had the most remote NPC (mean: 10.44 ± 3.07 cm). The mean NPC was 7.79 ± 2.93, 8.83 ± 2.72, and 9.63 ± 2.70 cm in emmetropic, myopic, and hyperopic participants, respectively. According to the results of a multiple linear regression model, NPC had a positive correlation with age (b: 0.058, p < 0.001), male sex (b: 0.336, p: 0.005), and hyperopia (b: 0.044, p: 0.011). Among the evaluated variables, age had the greatest effect on NPC (Standardized coefficient: 0.402). Conclusion: The distribution of NPC in the Iranian population is different from other populations. Since NPC is influenced by age more than any other variable and presented normal values according to age in this study, the results can be used to interpret clinical measurements for diagnosis and treatment purposes. © 2019 The Author