Purpose To determine the distribution of keratometric indices, corneal thickness, anterior chamber depth, pupil diameter and corneal diameter by Orbscan in a young Iranian population. Methods In this cross‐sectional study, samples were selected through multistage cluster sampling from among the students of Mashhad University of Medical Sciences, Iran. After performing refraction and retinoscopy, Orbscan was used for imaging. Results Of 1330 selected students, 1121 participated in the study. After applying the exclusion criteria, final analysis was performed on 1051 subjects. The mean age of the subjects was 26.1±3.2 years (19‐34 years old). The mean and 95% confidence interval (CI) of maximum keratometry, minimum keratometry, pupil diameter corneal diameter, anterior chamber depth, and central corneal thickness were 44.5(44.4‐44.6), 43.1(43.0‐43.2), 4.3(4.3‐4.4), 11.7(11.7‐11.7), 3.7(3.6‐3.7) and 550.5 (548.4‐552.6), respectively. After adjusting with age and spherical equivalent (SE), the maximum and minimum keratometry, thinnest corneal thickness were higher in females while the corneal diameter and anterior chamber depth were more in males. Corneal diameter and anterior chamber depth showed significant changes with age. The SE was only correlated significantly with maximum keratometry and anterior chamber depth. Conclusion The results of this study showed the normal ranges and averages of some Orbscan indices in a young Iranian population. The insignificant changes of the corneal diameter and anterior chamber depth with age and the differences between males and females in the evaluated indices should be considered in refractive surgery.

Purpose To determine the prevalence of visual impairment,low vision and blindness among the elderly of Sari in north of Iran. Methods Through cluster random sampling, 60 clusters were selected, out of which 20 people were systematically selected for this study. Participants received eye examinations including vision, actual visual acuity (AVA), optimal visual acuity (OVA) and refraction. Non‐cycloplegic refraction was performed with an auto refractometer and the results were checked with retinoscopy and subjective refraction. Visual impairment , low vision and blind were defined as vision worse than 20/60, 20/60 to 20/400 and worse than 20/400 in the better eye respectively. Results In this study, 937 people with mean age of 64.7±7.5 years old (from 55 to 87 years) were investigated. The prevalence of visual impairment, blindness, and low vision, based on actual visual acuity (AVA), were 11.0% (9.0‐13.0 CI 95%), 3.7% (2.5‐5.0 CI 95%), and 7.4% (5.7‐9.0 CI 95%), respectively. These findings were 3.7% (2.3‐5.1 CI 95%), 1% (0.2‐1.7 CI95%), and 2.7% (1.5‐3.9 CI 95%), based on OVA respectively. No significant difference was found between genders, but visual impairment was significantly higher in people over 75 years as compared with 55‐59 years old. The most common reasons for visual impairment based on AVA were refractive errors (68.6%) and cataract (16.7%). After correcting refractive errors, the most common causes of visual impairment were cataract (61.3%) and diabetic retinopathy (25.8%). Conclusion Refractive errors and cataract are the main causes of visual impairment in Iranian elderly. Correcting refractive errors and cataract reduces 85% of visual impairment based on AVA.

Purpose To assess the refractive error status in subjects with color vision deficiency (CVD) and color normal (CN) in order to make a contribution to a better understanding of emmetropization process. Methods A total of 4400 students were screened using a Ishihara pseudoisochromatic color vision plate set. One hundred and sixty students were detected to have CVD. Four hundred age and sex match were set as the control group. Objective refraction was performed to determine the refractive status of the subjects. Results The prevalence of myopia in CVD group was 7.7% that was significantly lower than CN subjects (13.9%). Furthermore, CVD group presented with lower prevalence of hyperopia (41%) in comparison with CN group (57.4%). In addition, CVD subjects were presented with lower magnitude of refractive error in comparison with NC. Conclusion Although lower prevalence of myopia support the theory of the role of Longitudinal chromatic aberration in refractive error development, lower prevalence of hyperopia in CVD group is in contrary with that. This Results indicated that longitudinal chromatic aberration is not the only factor that could influences the emmetropization process.

Purpose The aim of this study was to determine the prevalence and risk factors of near decompensated heterophoria in a population of university students. Methods In a randomized study, 406 students of six schools of Mashhad University of Medical Sciences were selected and classified into symptomatic and non symptomatic groups. Visual acuity (VA), near point of convergence (NPC), Near point of accommodation (NPA), dissociated and associated phoria, suppression, stereopsis, accommodative facility, relative accommodation, accommodative convergence/accommodation ( AC/A ratio and fusional reserves were measured in two groups. The data were analysed by using SPSS software, version 11.5o. Results The prevalence of symptoms and binocular disorders in students were 41.6% and 21.8% respectively . Of the students,9.1% had near decompensated heterophoria (heterophoria with symptoms). The results of this study showed that VA, NPC, NPA, heterophoria, stereopsis, accommodative facility, relative accommodation, AC/A ratio and fusional reserves were different in symptomatic and asymptomatic subjects and were worsen in students with decompensated heterophoria (P<0.05). Conclusion The results of this study indicated relatively high prevalence of symptomatic students, binocular dysfunction and decompensated heterophoria in university students. Students with decompensated heterophoria failed in more visual skills which can be risk factors for decompensating the heterophoria.

Purpose To investigate the association between ocular optical components and refractive errors in bank’s employees of Sari, Iran Methods In this cross sectional study 398 bank’s employees of Sari, Iran were selected, 232 of them used the eyes for close work (computers, etc…) for a minimum of 7 hours per day for the 5 past years. The other 166 bank’s employees acted as a control group and did not did a close work more than one hour daily for the 5 past years. Age of the participants were between 25 to 40 years old. Axial length, anterior chamber depth, lens diameter and vitreous depth were measured with Nidek biometer. Corneal radius and non cycloplegic refraction performed with autorefracto‐keratometer; refractive errors were checked by retinoscopy and subjective tests. There was a high correlation between equivalent sphere (ES) right and left eyes of the subjects (0.9) and data of the right eye was analyzed. Data were analyzed by using version 19 of SPSS software. Results The results showed that the bank’s employees who had excessive use of the eyes for near work have more axial length (p<0.001), more anterior chamber depth (p=0.003) and more vitreous chamber depth (p<0.001) than the control group. There was no significant difference between lens diameter (p=0.525) and cornel radius (p=0.666) of the two groups. There was correlation between axial length and SE by increasing in axial length (p<0.000). The least amount correlation was found between lens diameter and ES (P< 0.000). Conclusion The results of this study indicated that ocular optical components changed toward myopia in people who had excessive close work.