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Objective To determine the agreement between measurements of accommodative amplitude (AoA) in children using a specialised accommodative rule and measurments without it.Methods A total of 502 children underwent optometric examinations, including the measurement of visual acuity, objective and subjective refraction. AoA measurements were done with and without the Berens accommodative rule. The measurements of AoA were conducted monocularly using a −4 D lens. A fixation stick containing English letters equivalent to 20/30 visual acuity and a long millimetre ruler was used to measure AoA without the accommodative rule. This measurement was performed by the two trained examiners. The agreement between these methods was reported by 95% limits of agreement (LoA) and interclass correlation coefficient (ICC).Results The mean age of the participants was 11.7±1.3 years (range: 9–15 years) and 52.4% were male. The mean AoA with and without the accommodative rule was 20.02±6.02 D and 22.46±6.32 D, respectively. The 95% LoA between the two methods was −12.5 to 7.5 D, and the ICC was 0.67 (95% CI 0.63 to 0.70). The 95% LoA was narrower in higher age groups and males compared with females (18.92 vs 20.87). The 95% LoA was narrower in hyperopes (16.83 D) compared with emmetropes (18.37 D) and myopes (18.27 D). The agreement was not constant and decreased in higher values of AoA.Conclusion There is a poor and non-constant agreement between the measurements of the AoA with and without the accommodative rule. The mean AoA was 2.5 D lower with using the accommodative rule.

Abstract Purpose: The present study sets out to investigate the effect of cyclopentolate-induced cycloplegia on distance and near deviation and the accommodative convergence/accommodation (AC/A) ratio. Methods: This prospective study was performed on 30 subjects. The inclusion criteria included a lack of any active ocular pathology and systemic diseases, no history of ocular surgery, and nonuse of various medications. Refraction, near and distance deviation were measured for all subjects, and the same examinations were repeated after the administration of two drops of cyclopentolate 1% to both eyes. Results: The obtained data from 30 subjects, including 19 males, with a mean age of 22.53 ± 1.74 years were analyzed. The mean ± SD of near deviation in dry and cycloplegic conditions were –6.9 ± 8.1 and +6.4 ± 9.1 prism diopters, respectively, which were statistically significant (P < 0.001). Distance deviation in cycloplegic conditions demonstrated an average difference of 0.8 prism diopters, compared to dry conditions (P < 0.001). AC/A ratios were 4.7 ± 2.5 and 9.7 ± 3.9 (Δ/D) in non-cycloplegic and cycloplegic conditions, respectively, which was a statistically significant difference (P < 0.001). The multiple regression indicated that among all under study variables, refraction (B coefficient: –2.4; P < 0.001) and near pre-cycloplegic deviation (B coefficient: 0.56; P < 0.001) were significantly associated with post-cycloplegic near deviation. Conclusion: The results of this study indicated that cycloplegia causes a considerable esophoric shift in near deviation and a negligible esophoric shift in distance deviation. As a result, the AC/A ratio demonstrated a significant increase due to unequal changes in near and distance deviation.

Abstract 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.

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

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.

Purpose. To compare biometric and optical coherence tomography parameters as well as refractive status in preterm children aged 4–8 years with or without retinopathy of prematurity (ROP), and evaluate their correlations with age and gender-matched full-term children. Methods. Retrospective comparative cohort study of four groups of children. Children with a history of preterm birth, including ROP who received intravitreal bevacizumab (IVB) treatment, children with a history of ROP that regressed without treatment and those with no history of ROP were compared to age and gender-matched full-term children as a control group. Best corrected visual acuity (BCVA), spherical equivalent of refraction (SE), macular and choroidal thickness, as well as biometric parameters was measured. Results. A total of 120 eyes of 120 children (30 children in each group) were included. There was no significant difference in BCVA, SE, and subjective cylinder between groups (p=0.05, p=0.3, p=0.6, respectively). Axial length was significantly shorter, and the cornea was steeper in both ROP groups than in other groups (p=0.001, p

PURPOSE: This study used contrast sensitivity (CS) and optical coherence tomography (OCT) to assess the functional and structural alterations of the macula and the optic nerve head (ONH) in diabetic patients with no retinopathy and those with mild nonproliferative diabetic retinopathy (NPDR). MATERIALS AND METHODS: In this study, 40 eyes of 20 diabetic patients with no diabetic retinopathy (DR), 40 eyes of 20 diabetic patients with mild NPDR, and 36 eyes of 18 healthy individuals were examined. Best-corrected visual acuity (VA) and CS were performed using early treatment DR study charts and the Pelli-Robson chart, respectively. The macula and ONH were evaluated using OCT, which provided data on the entire retina, inner retinal layer, outer retinal layer, retinal nerve fiber layer (RNFL), and the macula zone-ellipsoid zone-retinal pigment epithelium layer. Results: VA and CS were significantly different between the three groups (P < 0.001). The entire thickness of the retina and the internal thickness of the retina in the 3–6 mm subfields of the macular region, as well as the thickness of the ganglion cell layer + inner plexiform layer (GCL + IPL) and GCL + IPL + RNFLs, differed significantly across the groups (P < 0.013). Conclusion: In diabetic subjects with no retinopathy, the reduced thickness of the GCL + IPLs is possibly indicative of early neurodegenerative changes in the inner retina. Furthermore, in the diabetic groups, a decrease in CS was observed compared to the control group.

Abstract Purpose: Assessment of the pattern visual evoked potential (PVEP) responses in different areas of visual fields in individuals with normal vision. Methods: This study was conducted on 80 eyes of normal subjects aged 18–35 years. All participants underwent refraction and visual acuity examination. Visual evoked potential (VEP) responses were recorded in different areas of field. The repeated measure test was used to compare the P100 latency and amplitude of PVEP among different areas. Results: The repeated measures analysis of variance showed a statistically significant difference among different areas in terms of amplitude and latency of P100 (P = 0.002 and P < 0.001, respectively). According to the results, the highest and lowest amplitude of P100 was observed in inferior-nasal and superior areas, respectively. The highest and lowest latency of P100 was related to the temporal and inferior-nasal areas, respectively. Conclusion: This study partially revealed the details of local PVEP distribution in the visual field and there was a significant difference in the amplitude and latency of PVEP wave in different areas of the visual field.

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.

Abstract Purpose: To determine the relationship between road accidents with visual acuity, refractive errors, visual field, and contrast sensitivity. Methods: This population-based case–control study was conducted on roads leading to Tehran Province, Iran. The case group comprised drivers who had met with accidents and were at fault for the accident. The cases were selected in an ongoing manner (incidence cases). The controls were drivers who were the opposing victims in the same. After an initial interview, optometric and ophthalmic examinations including the measurement of visual acuity, refraction, visual field assessment, contrast sensitivity measurement, and slit lamp biomicroscopy were performed for all study participants. Results: In this study, 281 and 204 individuals were selected for the case and control groups. The mean uncorrected visual acuity was 0.05 ± 0.12 and 0.037 ± 0.10 logMAR in the case and control groups, respectively (P = 0.095). Of the participants in the case and control groups, 32.8% and 23% had a visual field defect in at least one eye, respectively (adjusted odds ratios [aOR] = 1.63, 95% confidence interval [CI]: 1.08–2.48; P = 0.021). Moreover, 16.2% of the cases and 8.3% of the controls had visual field defects in both eyes (aOR = 2.13, 95% CI: 1.17–3.86; P = 0.012). Contrast sensitivity was worse in the case group in all spatial frequencies under non-glare conditions. However, under glare conditions, the contrast sensitivity was significantly worse in the case group only in the spatial frequency of 12 cycles per degree (cpd). Conclusion: Reduced contrast sensitivity, especially under non-glare conditions, and visual field defects are risk factors that influence the prevalence of road accidents. It is strongly advised that special attention be paid to these visual functions in legal assessments to apply the necessary interventions in individuals with these types of disorders.

Abstract Purpose The aim of this study was evaluate the effect of governmental support in the form of Health Transformation Plan (HTP) on increasing the cataract surgical rate. Methods The number of cataract surgeries was collected from Iranian cataract surgery clinics during 2019. HTP was implemented in 2014. Forty-seven major and forty-five minor surgery centers were selected from all provinces. In each center, sampling was done from 2012, 2013, 2015, and 2016. Results On average, 6202 and 7134 cataract surgery rate were performed before and after HTP, respectively. The cataract surgical rate rose by 15.03% after the HTP. After HTP, the proportion of cataract surgery increased by 21.32% in governmental centers and decreased by 17.56%, 24.45%, and 14.89% in private, insurance, and charity centers, respectively. The cataract surgical rate was 4093 and 6026 in the first economic quartile (the poorest), 3669 and 4595 in the second quartile, 5884 and 5928 in the third quartile, and 8427 and 9681 in the fourth quartile (the richest) before and after HTP, respectively. The highest growth in the cataract surgical rate was seen in the first quartile (47.24%) followed by the second (25.26%), fourth (14.88%), and third quartiles (0.74%). Conclusion The Health Transformation Plan has been successful in increasing the cataract surgical rate in the low-income group and identifying differences in the services as well as the economic groups within the population.

Abstract Purpose To determine the age and sex-standardized prevalence of corneal arcus and its associated factors in a geriatric population. Methods This population-based cross-sectional study was conducted in 2019 in Tehran; the capital of Iran, using a multi-stage stratified random cluster sampling method. All participants underwent a detailed interview, blood pressure measurement, laboratory blood tests, and a complete ocular examination. Results Three thousand three hundred ten of 3791 invitees participated in the study (response rate: 87.31%). The mean age of the participants was 69.35 ± 7.62 years (60–97 years) and 1912 (57.76%) were female. Overall, the age and sex-standardized prevalence (95% CI) of corneal arcus was 44.28% (41.21–47.39). Based on the multiple logistic regression, the odds of corneal arcus were higher in men than in women (OR: 1.51; 95% CI: 1.14–2.00); in the age group ≥ 80 years compared to the age group 60–64 years (OR: 2.44; 95% CI: 1.68–3.53), and in retired people compared to employed individuals (OR: 2.05; 95% CI: 1.31–3.21). Conclusion The present study showed a high prevalence of corneal arcus in the geriatric population. Although various studies have reported a significant relationship between corneal arcus with blood lipid and glucose levels as well as blood pressure, these relationships were not found in the present study.

Abstract Aim To determine the prevalence of ocular trauma in Iranian children aged 6–12 years. Methods This population-based cross-sectional study, comprised the first phase of the Shahroud Schoolchildren Eye Cohort Study on primary school children using cluster sampling in urban areas and census in rural areas. The students underwent the measurement of uncorrected and corrected visual acuity as well as non-cycloplegic, cycloplegic, and subjective refraction. The history of trauma, hospitalization, and surgery due to trauma was collected from parents using a questionnaire. Results The data of the trauma history was recorded for 5267 out of 5620 students. The mean age of the students was 9.7 ± 1.7 years (range: 6–12 years), 53.7% of them were boys, and 79.3% were from urban areas. A positive history of ocular trauma was found in 285 participants, and the lifetime prevalence of ocular injury (95% CI) was 5.2% (4.6–5.9). Blunt trauma was the most common ocular injury with a prevalence of 66.2%. There was a significant positive assocation between ocular trauma and living in rural areas (OR: 1.49, p: 0.012), older age (OR: 1.17, p

Abstract Purpose: To evaluate varied aspects of binocular function in multiple gaze positions. Methods: In 2018, this cross-sectional study was conducted on 21 participants (male = 11) with an age range of 19–25 years. Having emmetropia and 10/10 visual acuity in both eyes were conditions of the inclusion criteria for the cross-sectional study. The following aspects of binocular function including amplitude of accommodation (AA), near point of convergence, near phoria, and monocular accommodative facility were evaluated in five gazes (primary, upward, downward, left, and right) for all subjects. Results: Near point of convergence values showed significant differences in all gaze positions (P < 0.001). The lowest near point of convergence value was seen in the primary gaze (2.69 cm) and the downward gaze (3.47 cm) and the highest near point of convergence value was seen in the left gaze (7.5 cm). There was also a significant difference in the amplitude of accommodation among the upward, downward, and the primary gaze (P < 0.001) positions but no difference was observed among the temporal, nasal, and the primary gaze positions. There was a significant difference in near phoria between the upward gaze and the primary gaze (P = 0.008) while no significant differences were observed among the other gazes. There was no significant variance in the monocular accommodative facility among the different gaze positions (P = 0.175). Conclusion: The results of this study indicated variations that exist in the convergence and accommodation reflex functions in multiple gaze positions, which proved to be more prominent in the convergence system. Although the accommodative sufficiency evaluation was inconsistent among the multiple gaze positions, the accommodative facility evaluation was consistent in all gazes.

Abstract To determine the repeatability of biometric measurements by dual Scheimpflug Devices with Integrated Optical Biometers and its agreement with partial coherence interferometry according to the axial length (AL), and the presence of cataracts. The present population-based cross-sectional study was conducted on the geriatric population in Tehran. For participants, imaging was performed by dual Scheimpflug Devices with Integrated Optical Biometers (Galilei G6) and partial coherence interferometry (IOL Master 500). All measurements were performed by one person. In both normal and cataractous eyes, the ICC values were above 0.99 for three measurements of AL, intraocular lens (IOL) power target, anterior chamber depth (ACD), central corneal thickness (CCT), flat and steep keratometry readings, and mean total corneal power (MTCP). The repeatability coefficient for the AL measurements was 0.003 and 0.002 in eyes with and without cataracts, respectively. The mean difference of AL between IOL Master 500 and Galilei G6 in normal and cataractous eyes was 0.015 and −0.003 mm, respectively. The 95% limits of agreement (LoA) of AL between these two devices were −0.09 to 0.12 mm in normal and −0.09 to 0.08 mm in cataractous eyes. The 95% LoA of ACD between the two devices was −0.13 to 0.36 mm and −0.10 to 0.31 mm in eyes without and with cataracts, respectively. The 95% LoA of steep K between the two devices was −0.63 to 0.32 and −1.04 to 0.89 diopter in normal and cataractous eyes, respectively. The results of the present study indicate the high repeatability of Galilei G6 in ocular biometric measurements. Galilei biometric measurements, had a very high agreement with the IOL Master 500.

To evaluate the effect of dry eye disease (DED) on the central corneal thickness and anterior corneal surface irregularity parameters using Scheimpflug tomography. In this study, the central corneal thickness and topometric indices of the anterior corneal surface were compared between the right eyes of 43 subjects with dry eye (DE group) and the right eyes of 35 non-dry eye individuals (NDE group). The central corneal thickness (CCT) and the topometric indices of the anterior corneal surface, including IVA, IHA, ISV, and IHD, were measured using the Pentacam HR (Pentacam-HR, Oculus, Wetzlar, Germany). Dry eye was diagnosed using a symptom questionnaire, TBUT, and Schirmer’s test without anesthesia. The mean ISV, IVA, IHA, and IHD were 17.02 3.43, 0.114 0.04, 5.82 4.82, and 0.011 0.01 in the DE group and 14.65 3.10, 0.086 .03, 3.70 3.23, and 0.007 0.00 in the NDE group, respectively. All of the above corneal irregularity indices were significantly higher in the DE group (P

To investigate the prevalence of Meibomian gland dysfunction (MGD) and its relationship with some determinants in underserved villages of Iran. This population-based cross-sectional study was conducted on 3850 subjects that were randomly selected from the villages of two underserved districts in the north and southwest of Iran using multistage cluster sampling. All participants underwent complete ophthalmic examinations, including visual acuity and refraction measurement. Then, slit-lamp biomicroscopy was done by an ophthalmologist to investigate MGD. Of 3850 subjects that were invited, 3314 participated in the study (participation rate=86.07%), of whom 1834 (55.34%) were women. The mean age of the participants was 37.7±21.4 years (range=2-93 years). The prevalence (95% CI) of MGD in at least one eye was 29.20% (27.35 to 31.06). According to the results of multiple regression analysis, MGD had a positive association with the male sex (OR: 1.75; CI 95%: 1.44 to 2.13), age 61-70 years (OR: 7.15; CI 95%: 3.65 to 14.01), and living in southern villages (OR: 1.82; CI 95%: 1.48 to 2.22) and an inverse association with education level (OR: 0.89; CI 95%: 0.80 to 0.98). The results of this study showed a lower prevalence of MGD even in Iranian rural regions compared to other Asian countries. This study found that older age, male sex, and low education level served as MGD risk factors. It seems that improved health conditions are an important factor in preventing MGD.

Purpose: To determine and compare ocular characteristics and refractive errors between thalassemia major patients and normal subjects. Methods: In this study, 71 thalassemia major patients and 79 age and sex matched healthy subjects that were selected in an ongoing manner underwent complete optometric and ophthalmic examinations including auto refraction, subjective refraction, fluorescein tear break- up time, and pachymetry after anthropometric measurements. Results: The results showed that the mean UCVA was better in the control group versus the thalassemia group (p

Background: We aimed to determine the age and sex standardized prevalence of corneal opacity and its determinants Methods: The Tehran Geriatric Eye Study (TGES) is a population-based cross-sectional study conducted on 3791 subjects aged above 60 yr in Tehran, Iran (2019) selected using stratified random cluster sampling. After sampling, all subjects underwent complete ophthalmic, optometric, and eye examinations. Results: The 3310 participated in the study, of whom the data of 3284 were analyzed. The age and sex standardized prevalence with 95% confidence interval (CI) of corneal opacity in at least one eye, both eyes, and one eye was 9.58% (95% CI: 8.50 to 10.79), 5.52% (95% CI: 4.71 to 6.45), and 4.07% (95% CI: 3.35 to 4.94), respectively. The mean uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) according to LogMar were worse in subjects with corneal opacity (both P80 yr (OR: 2.05; P: 0.004), and lack of insurance coverage (OR: 1.87; P: 0.004) increased the odds and high school education (OR: 0.68; P: 0.003) reduced the odds of corneal opacity. Among the study variables, sex was the most important determinant of corneal opacity (standardized beta: 0.126). Conclusion: This study found a high prevalence of corneal opacity in the geriatric population. Considering the increasing trend of population aging in Iran, attention should be paid to prioritizing public health policies to estimate resources required for providing comprehensive corneal services and improving geriatric eye health.

To evaluate and compare posterior corneal elevation data and anterior segment parameters in different grades of keratoconus by Pentacam. 114 eyes of 114 keratoconic patients (85 men and 56 women) with a mean age of 31.6±4.7 years were evaluated with a Pentacam Scheimpflug camera. Keratoconic eyes were divided into 3 groups or grades according to the maximum keratometry reading: mild or grade I (K=50 or less than 50 diopters [D]), moderate or grade II (K=50.0 to 55.0 D), and severe or grade III (K=55.0 D or higher). The posterior corneal parameters were obtained posterior. There were no statistically significant differences between keratoconus grades in terms of sex (P=0.661). Also, there were no statistically significant differences between 3 grades in terms of age (P=0.214). There were statistically significant differences in anterior keratometry readings (K), anterior chamber depth (ACD), anterior chamber angle (ACA), and all pachymetric corneal measurements between all groups. With the progression of the disease, posterior K readings and all posterior elevation measurements were statistically different between the three grades. However, there were no significant differences in pupil diameter, anterior chamber volume (ACV), and corneal volume (CV) between the three grades of keratoconus. According to the results of this study, height data of posterior elevation, when combined with corneal anterior segment parameter, could provide a useful keratoconus severity classification tool.

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.

Purpose: To determine the agreement of table-mounted and handheld auto-refractometers and to evaluate the effect of age and different types of refractive errors on this comparison. Methods: In this cross-sectional study conducted in 2015 using multi-stage cluster sampling, two underserved villages were selected randomly in the north and southwest of Iran. All the selected participants underwent optometric and ophthalmic examinations. Refraction was measured using handheld and table-mounted auto-refractometers in 652 subjects. Results: The mean age of the subjects was 32.7 ± 18.72 years, and 58.3% of them were female. A significant difference was observed in the results of sphere, spherical equivalent (SE), and J45 vector between the two devices (P

Purpose: To determine the distribution of iris color and its relationship with some ocular diseases in a rural population of Iran. Methods: Two rural areas of the north and southwest of Iran were selected by a cross-sectional study using multi-stage cluster sampling. After selecting samples, the participants had an eye examination including measuring visual acuity, refraction, and Pentacam imaging. Then an eye examination for individuals was performed by slit-lamp. Results: Out of 3851 invited people, 3314 participated in this study (participation rate, 86.05%). Dark brown [41.28%, confidence interval (CI) 95% = 31.88–50.68] and blue (0.99%, CI 95% = 0.57–1.41) were the most and the least type of iris colors among participants of this study. Compared to others, people with a dark iris have the biggest anterior chamber depth (ACD), angle and volume while central corneal thickness (CCT), keratometry and pupil were highest among people with a dark brown iris (P

Purpose: To evaluate the demographic profile, clinical, and topographic characteristics of keratoconus (KCN) patients attending at a subspecialty eye hospital in Tehran, Iran. Methods: In this cross-sectional study, all patients who attended Noor Eye Hospital between March 2011 and March 2017 and had a diagnosis of KCN were identified, and the required number of patients was randomly selected. The following data were extracted from patient's records: age, sex, visual acuity, refraction, keratometry, pachymetry, and treatment procedures. The data of KCN laterality, severity, morphology, and cone location were also extracted by analyzing the corneal imaging maps. Results: The records of 1080 eyes of 540 patients were evaluated. The mean age of the participants was 31.04 ± 8.54 years (range, 13–63 years), and 69.3% of the patients were male. The highest and lowest frequency of KCN was seen in the age group 20–30 years and above 50 years, respectively. Bilateral KCN was detected in 93.3% [95% confidence interval (CI): 91.68–94.75] of the subjects. 43.7% (95%CI: 32.88–54.48), 55.6% (95%CI: 44.73–66.38), and 0.8% (95%CI: 0.75–0.78) of the cases had nipple, oval, and globus cones, respectively. The cone was central in 52.1% (95%CI: 41.10–63.11), paracentral in 43.6% (95%CI: 36.13–51.04), and peripheral in 4.3% (95%CI: 00.76–7.86) of the cases. The frequency percentage of KCN according to severity was 15.2% (95%CI: 13.09–17.46), 56.4% (95%CI: 53.37–59.37), and 28.4% (95%CI: 25.75–31.21) for mild, moderate, and severe KCN, respectively. Among different parameters, only cone location had a significant association with age as the frequency of paracentral and peripheral cones increased with ageing (P = 0.002). Conclusions: The mean age of KCN patients in our study was higher than similar studies in other Asian countries. KCN was bilateral in most cases with an oval morphology and central cone location. Most of the patients had moderate to severe KCN. Keywords: Keratoconus, Demographic profile, Clinical characteristics, Subspecialty hospital, 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.

Purpose: To determine 4-year changes of ocular biometric and dioptric components in Iranian children aged 7–11 years following the first phase. Methods: 468 children were evaluated in the first phase of the study in 2012 and again in 2016–2017. Multi-stage stratified cluster sampling was applied to select the participants. The Topcon autorefractometer and the LENSTAR/BioGraph biometer (WaveLight AG, Erlangen, Germany) were used for cycloplegic refraction and biometry, respectively. All measurements were repeated at 4 years as the baseline assessments. Results: Of 468 children, 251 (53.6%) were boys. Spherical equivalent (SE) showed a marked myopic shift (P = 0.000) in the second phase which was significantly higher in boys (0.24 vs. 0.18 D) (P 0.05). Conclusions: Statistical and clinical changes were seen in AL, ACD, LP, and LT. The changes observed in biometric components (AL, ACD, and LT) had a sinus rhythm. Keywords: Ocular dioptric component, Children, Biometry, Axial length, Lens power, Keratometry, Age, Sex

Purpose: To determine the central corneal thickness (CCT), apex, and paracentral thicknesses and their determinants in children aged 6–12 years. Methods: The present study was part of the phase 1 of Shahroud School Children Eye Cohort Study in 2015. Cluster sampling was done in urban areas while all children were invited to participate in the study in rural areas. The Pentacam HR was used for measurements. CCT was measured within the central 3 mm zone of the cornea, and corneal thickness 3 mm further from the center was considered paracentral thickness. Results: Of 6624 students who were selected, 5620 (84.8%) participated in the study. Among 4956 students, studied in this report, 52.2% were boys, and the mean age of the study participants was 9.75 ± 1.71 years (6–12). The mean CCT and apical thickness was 556.29 ± 34.04 and 557.43 ± 34.03 μm, respectively. The mean paracentral thickness was 657.62 ± 39.11 μm in the superior, 632.65 ± 37.63 μm in the inferior, 648.64 ± 38.75 μm in the nasal, and 617.36 ± 37.19 μm in the temporal region. A multiple regression model showed that CCT decreased by 4.70 μm with every 1 diopter increase in the mean keratometry and increased by 20.06 μm with every 1 mm increase in the anterior chamber depth (ACD) (Both P-Value

Purpose: To evaluate the diagnostic value of visual evoked potentials (VEPs) and to find out which test setting has the most sensitivity and specificity for amblyopia diagnosis. Methods: Thirty-three adult anisometropic amblyopes were intended in this study and were tested for visual evoked potentials with different stimulus conditions including three spatial frequencies [1, 2, and 4-cycles-per-degree (cpd)] at four contrast levels (100, 50, 25, and 5%). We also tested psychophysical contrast sensitivity and compared the results with electrophysiological ones. We plotted Receiver Operating Characteristic (ROC) curve for each VEP recording and psychophysical contrast sensitivity to evaluate the area under the curve, sensitivity, specificity, and cut-point value of each test stimulus for detecting amblyopic eyes. Results: Thirty-three amblyopic and 33 non-amblyopic eyes were examined for psychophysical contrast sensitivity and VEPs. Area under the ROC curve (AURC) findings showed that VEP with different stimulus settings can significantly detect amblyopic eyes, as well as psychophysical contrast sensitivity test. We found that P100 amplitudes had the largest AURC in response to stimuli of 2-cpd spatial frequency at 50 (P

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-15

Purpose: To determine the effect of isotretinoin on corneal sensitivity in acne patients. Methods: Fifty patients (13 men and 37 women) with a mean age of 23.24 ± 3.4 years were selected among patients receiving isotretinoin (1.0 mg/kg) for acne according to inclusion criteria. The Cochet-Bonnet esthesiometer was used to measure corneal sensitivity (in mm filament length) two times (the measurements were done immediately before starting the medication, then 3 months after that), including 3 measurements each time, between 11 a.m. and 1 p.m. by an experienced operator. The average of the 3 measurements in each time was recorded as the final value. One-way analysis of variance and Chi square were used for quantitative and qualitative comparison of corneal sensitivity before and after isotretinoin use, respectively. Results: The mean corneal sensitivity was 5.54 ± 0.05 before medication consumption which decreased to 5.41 ± 0.05 after isotretinoin treatment for 3 months (P

Purpose: This study aimed to evaluate two psychophysical contrast sensitivity testing methods in amblyopic patients. Methods: Thirty-three adults with anisometropic amblyopia participated in this study. Psychophysical contrast sensitivity was measured for both amblyopic and fellow eyes of the participants at 1, 3, and 5 cycles per degree (cpd) spatial frequencies by Freiburg visual acuity and contrast test (FrACT) and Metrovision contrast sensitivity test, which employ sine-wave gratings for measurement of contrast sensitivity. We evaluated the correlation between the two tests and used Bland–Altman analysis to measure the agreement between the two methods. Results: Except for 1 cpd in amblyopic eyes, FrACT showed significantly higher contrast sensitivity measurements than Metrovision at all spatial frequencies both in normal and amblyopic eyes (P

Purpose: To determine the rate of excimer laser refractive surgery in Iran and its trend during 2010–2014, and the number of surgeries per ophthalmologist. Methods: Twelve provinces were considered for the study; 4 major referral provinces of Tehran, Fars, Isfahan, and Khorasan, and 8 others which were selected randomly. Then a number of excimer laser centers were chosen from each province. In the timeframe between 2010 and 2014, one week per season was randomly selected for each center, and the number of surgeries conducted in these 20 weeks was determined by trained personnel. Results: In the 12 surveyed provinces, 28 of the 57 active surgical centers were selected. The rate of excimer laser refractive surgery in 2010 in Iran was 2764 per million population which reached 3744 per million by 2012 and took a slightly decreasing trend to 3582 until 2014. Based on the number of ophthalmologists and the number of surgeries in 2014, the average number of surgeries per ophthalmologist was 103 surgeries. Conclusion: This is the first study to report the rate of excimer laser refractive surgery in Iran. Keywords: Laser refractive surgery, Iran, Trend, Ophthalmologist

Purpose: To determine the prevalence of hyperopia and myopia and their associations with age and gender in 5- to 15-year-old children in underserved rural areas in Iran. Methods: In this cross-sectional study, sampling was done using a multistage cluster sampling method from two underprivileged rural regions in Iran, and 3851 persons over 1 year old of age were invited to the study. After inviting the selected participants, examinations were conducted at a designated site in the selected villages. All participants underwent measurements of uncorrected and corrected visual acuity, manifest refraction, and a slit-lamp examination. Cycloplegic refraction was done by instilling cyclopentolate 1% eye drops in under 15-year-old participants. Results: Of the 3851 selected persons, 3314 subjects participated (86.5%), and of these, 602 were in the 5–15 year age group. The prevalence of myopia and hyperopia in the studied children was 2.60% [95% confidence interval (CI): 1.10–4.10] and 4.00% (95% CI: 1.84–6.15), respectively. The prevalence of myopia in male and female children was 2.65% and 2.55%, respectively (P = 0.951). The prevalence of hyperopia in male and female children was 2.83% and 5.25%, respectively (P = 0.130). The prevalence of myopia in the villages of southwest and north was 2.42% and 3.09%, respectively (P = 0.618), and the prevalence of hyperopia was 4.71% and 2.10%, respectively (P = 0.0056). Conclusion: The present report is a brief description of the status of refractive errors in children residing in underprivileged villages of two rural districts in Iran. As presented, the prevalence of myopia is not high, although the prevalence of hyperopia is in the mid-range compared to previous studies. Keywords: Myopia, Hyperopia, Cross-sectional study, Rural population, Children

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

Purpose: To determine the normal range of intraocular pressure (IOP) in the young and its association with certain corneal parameters using a non-contact device. Methods: Subjects were selected from students of Mashhad University of Medical Sciences through stratified sampling. All participants had visual acuity testing, corneal imaging, a comprehensive slit-lamp examination by an ophthalmologist, and IOP measurement using a non-contact air-puff tonometer. Results: Of the 1280 invitees, 1073 (83.8%) participated, and 1027 were eligible. Mean IOP was 16.38 mmHg [95% confidence interval (CI): 16.22–16.53] in the total sample, 16.14 mmHg (95% CI: 15.84–16.45) in men, and 16.48 mmHg (95% CI: 16.31–16.66) in women. There was a significant IOP difference between myopes and emmetropes (P = 0.031). Based on the multiple linear regression model, IOP associated directly with age and central corneal thickness (CCT), and inversely with corneal diameter, spherical equivalent (SE), and keratoconus. Based on standardized coefficients of the regression model, CCT and SE had the strongest association with IOP. Conclusions: In the present study, we demonstrated the IOP distribution in a young population using a non-contact method. CCT and SE were strongly associated with IOP.

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.

Purpose: To determine the prevalence of uncorrected refractive errors, need for spectacles, and the determinants of unmet need in underserved rural areas of Iran. Methods: In a cross-sectional study, multistage cluster sampling was done in 2 underserved rural areas of Iran. Then, all subjects underwent vision testing and ophthalmic examinations including the measurement of uncorrected visual acuity (UCVA), best corrected visual acuity, visual acuity with current spectacles, auto-refraction, retinoscopy, and subjective refraction. Need for spectacles was defined as UCVA worse than 20/40 in the better eye that could be corrected to better than 20/40 with suitable spectacles. Results: Of the 3851 selected individuals, 3314 participated in the study. Among participants, 18.94% [95% confidence intervals (CI): 13.48â24.39] needed spectacles and 11.23% (95% CI: 7.57â14.89) had an unmet need. The prevalence of need for spectacles was 46.8% and 23.8% in myopic and hyperopic participants, respectively. The prevalence of unmet need was 27% in myopic, 15.8% in hyperopic, and 25.46% in astigmatic participants. Multiple logistic regression showed that education and type of refractive errors were associated with uncorrected refractive errors; the odds of uncorrected refractive errors were highest in illiterate participants, and the odds of unmet need were 12.13, 5.1, and 4.92 times higher in myopic, hyperopic and astigmatic participants as compared with emmetropic individuals. Conclusion: The prevalence of uncorrected refractive errors was rather high in our study. Since rural areas have less access to health care facilities, special attention to the correction of refractive errors in these areas, especially with inexpensive methods like spectacles, can prevent a major proportion of visual impairment. Keywords: Uncorrected refractive errors, Population-based study, Unmet need

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 East

Purpose: To determine the one-year incidence of needle stick and sharp injuries (NSIs and SIs) and their associations with visual function among Iranian nurses. Methods: In this cross-sectional study, 278 nurses working at one hospital were selected through stratified random sampling. After applying the exclusion criteria, the final analysis was performed on the data of 267 nurses. The data of occupational injuries were collected through a researcher-administered questionnaire. Visual function indices including distance and near best corrected visual acuities (BCVAs), color vision, stereoacuity, distance and near heterophorias, accommodative amplitude and facility, contrast sensitivity (CS) for high and low spatial frequencies (SFs), near point of convergence (NPC), saccadic and pursuit eye movements, distance and near convergence and divergence fusional reserves and peripheral vision were evaluated through optometric examinations using standard protocols. Results: The one-year incidence of NSIs and SIs was 41.2% [95% Confidence interval (CI): 35.3–47.1] and 19.1% (95% CI: 14.4–23.8), respectively. Color vision deficiency, pursuit deficiency, abnormal near heterophoria, and decreased CS for high SF had a significant association with the increased incidence of NSIs with odds ratios of 3.26, 2.32, and 1.35, respectively. Moreover, saccadic deficiency, abnormal near heterophoria, and decreased near fusional divergence reserve were significantly associated with the increased incidence of SIs with odds ratios of 2.42, 2.40, and 1.27, respectively. Conclusions: Our findings showed a relatively high incidence of NSIs and SIs in Iranian nurses and their associations with some visual function indices. Therefore, pre-employment and periodic visual examinations are recommended to detect and remove the corresponding visual risk factors. Moreover, preventive strategies should be adopted to decrease the occurrence of the aforementioned injuries. Keywords: Needle stick injuries, Sharp injuries, Visual function, Nurses

Purpose: To assess the diagnostic power of the Corneal Visualization Scheimpflug Technology (Corvis ST) provided corneal biomechanical parameters in keratoconic corneas. Methods: The following biomechanical parameters of 48 keratoconic eyes were compared with the corresponding ones in 50 normal eyes: time of the first applanation and time from start to the second applanation [applanation-1 time (A1T) and applanation-2 time (A2T)], time of the highest corneal displacement [highest concavity time (HCT)], magnitude of the displacement [highest concavity deformation amplitude (HCDA)], the length of the flattened segment in the applanations [first applanation length (A1L) and second applanation length (A2L)], velocity of corneal movement during applanations [applanation-1 velocity (A1V) and applanation-2 velocity (A2V)], distance between bending points of the cornea at the highest concavity [highest concavity peak distance (HCPD)], central concave curvature at the highest concavity [highest concavity radius (HCR)]. To assess the change of parameters by disease severity, the keratoconus group was divided into two subgroups, and their biomechanical parameters were compared with each other and with normal group. The parameters' predictive ability was assessed by receiver operating characteristic (ROC) curves. To control the effect of central corneal thickness (CCT) difference between the two groups, two subgroups with similar CCT were selected, and the analyses were repeated. Results: Of the 10 parameters compared, the means of the 8 were significantly different between groups (P 0.05). ROC curve analyses showed excellent distinguishing ability for A1T and HCR [area under the curve (AUC) > 0.9], and good distinguishing ability for A2T, A2V, and HCDA (0.9 > AUC > 0.7). A1T reading was able to correctly identify at least 93% of eyes with keratoconus (cut-off point 7.03). In two CCT matched subgroups, A1T showed an excellent distinguishing ability again. Conclusions: The A1T seems a valuable parameter in the diagnosis of keratoconic eyes. It showed excellent diagnostic ability even when controlled for CCT. None of the parameters were reliable index for keratoconus staging. Keywords: Keratoconus, Cornea, Corvis ST, Biomechanics

Purpose: To determine the distribution of negative relative accommodation (NRA) and positive relative accommodation (PRA) and its relationship with binocular vision indices in a young population. Methods: In this cross-sectional study conducted in a student population, samples were selected through multistage cluster sampling. All the samples underwent the measurement of uncorrected and corrected visual acuity and refraction. Then far and near cover tests were performed. The near point of convergence (NPC) and accommodation, accommodation facility, PRA and NRA were evaluated in all participants. Results: The mean age of the 382 participants was 22.5 ± 4.4 years (18–35 years). Mean NRA and PRA in the total sample was +2.08 ± 0.33 diopter (D) and −2.92 ± 0.76 D, respectively. Mean NRA was highest in hyperopic (P = 0.002) and mean PRA was highest in myopic (P = 0.003) participants.The multiple model showed that NRA had a direct relationship with accommodation facility and spherical refractive error, while PRA had a direct relationship with amplitude of accommodation (AA). Conclusion: This study provides the normal range of the NRA and PRA and their relationship with accommodation facility, spherical refractive error, and AA in a sample of the Iranian population. Keywords: Negative relative accommodation, Positive relative accommodation, Population based study, Accommodation facility

Introduction: This article aimed to review the literatures on visual impairments and ocular changes in premature infants with low birth weight and gestational age.Methods: Five electronic databases including: PubMed, Web of Science, Science direct, Ovid, and Scopus were searched. Original articles published until 2015 describing preterm infants were reviewed. Repetitive and derivative articles were excluded.Results: Out of 100 unique, potentially relevant articles, 42 studies that addressed and met the inclusion criteria were evaluated.Conclusion: Prematurity affects ocular structures (from anterior to posterior segment) and functions. Premature infants are at risk of myopization. Concerning the changes in premature infants, a significant increase is found in axial length, intraocular pressure, and central corneal thickness; moreover, high incidence of retinal changes is reported as a result of prematurity. On the other hand, visual acuity, tear, electroretinogram, and visual evoked potential responses decrease with prematurity. The most common ophthalmic disorders in preterm infants are myopia and retinopathy of prematurity, which could affect life quality due to reduced visual acuity.

Purpose: To compare four tonometry techniques: Goldmann applanation tonometer (GAT), Dynamic contour tonometer (DCT), Non-contact tonometer (NCT), and Ocular Response Analyzer (ORA) in the measurement of intraocular pressure (IOP) and the impact of some corneal biomechanical factors on their performance. Methods: In this cross-sectional study, volunteers with normal ophthalmic examination and no history of eye surgery (except for uncomplicated cataract surgery) or trauma were selected. Twenty-five subjects were male, and 21 were female. The mean age was 48 ± 19.2 years. Anterior segment parameters were measured with Scheimpflug imaging. IOP was measured with GAT, DCT, NCT, and ORA in random order. A 95% limit of agreement of IOPs was analyzed. The impact of different parameters on the measured IOP with each device was evaluated by regression analysis. Results: The average IOP measured with GAT, DCT, NCT, and ORA was 16.4 ± 3.5, 18.1 ± 3.4, 16.2 ± 3.9, and 17.3 ± 3.4 mmHg, respectively. The difference of IOP measured with NCT and GAT was not significant (P = 0.382). Intraocular pressure was significantly different between GAT with DCT and IOPCC (P

Purpose: To determine the distribution of anterior eye biometry indices, such as keratometry pachymetry, anterior chamber depth (ACD), pupil diameter, and corneal diameter, as measured by Orbscan instrument in a young Iranian population. Methods: A cross-sectional study was conducted, and subjects were selected through multistage cluster sampling from the students of Mashhad University of Medical Sciences. Objective and subjective refraction were performed followed by Orbscan imaging. Results: A total of 1330 subjects were selected, 1121 of which participated in the study. After applying the exclusion criteria, the final analysis was performed on the data of 1051 subjects. The mean age of the participants was 26.1 ± 3.2 years (19–34 years old). The mean ± SD and 95% confidence interval (CI) of maximum keratometry, minimum keratometry, pupil diameter, corneal diameter, ACD, and central corneal thickness was 44.5 ± 1.7 (44.4–44.6), 43.1 ± 1.6 (43.0–43.2), 4.3 ± 0.9 (4.3–4.4), 11.7 ± 0.4 (11.7–11.7), 3.7 ± 0.3 (3.6–3.7), and 550.5 ± 35 (548.4–552.6), respectively. After adjusting for age and the mean spherical equivalent (MSE), maximum keratometry, minimum keratometry, central corneal thickness, and the thinnest pachymetry were statistically significantly higher in female subjects (P

Purpose: To determine the repeatability of corneal thickness measurements with Scheimpflug (Pentacam) and slit scanning (Orbscan) imaging techniques in different grades of keratoconus. Methods: This study was conducted as a cross-sectional research. Imaging with Orbscan and Pentacam was performed on patients with different grades of keratoconus. With each device, 3 measurements were taken at 10 min intervals. Repeatability indices in different grades of keratoconus were calculated for each device. Results: Seventy-four eyes of 42 keratoconus patients were enrolled. Repeatability index (RI) of central corneal thickness (CCT) measurements in keratoconus grade 1, 2, and 3, were 12.8, 9.9, and 24.2 with Pentacam, and 23.6, 26.3, and 59.3 with Orbscan, respectively. For the thinnest point, these figures were 9.6, 8.0, and 35.7 with Pentacam and 19.5, 16.6, and 26.8 with Orbscan, respectively. The 95% limit of agreement (LOA) between Pentacam and Orbscan in measuring CCT and thinnest point in grade 1 were −25.5–47.7 mic and −33.3–32.8 mic, respectively. These results for grade 2 were −9.8–50.6 mic and −26.2–43.7 mic, respectively. In grade 3, 95% LoA were −20–64.6 mic and −31.4–60.5 mic, respectively. Conclusions: The results of this study showed that although repeated measurements of the CCT with Orbscan and Pentacam are strongly correlated, repeatability values of CCT measurements significantly decrease at more advanced grades of keratoconus. In all keratoconus grades, repeatability of CCT measurements was better with Pentacam than Orbscan. These findings indicate that corneal thickness readings have less validity in patients with advanced keratoconus.

Purpose: To compare the visual responses of post refractive surgery's patients using Early Treatment Diabetic Retinopathy Study Chart (ETDRS) and E-chart with and without color filters. Methods: The uncorrected Logarithm of the Minimum Angle of Resolution Visual Acuity (LogMAR VA) of 70 patients with a mean age of 26.2 ± 3.76 years (from 19 to 34 years) who had undergone Photorefractive Keratectomy (PRK) (the range of post operation refractive error: ±0.5 D) was measured under the light conditions of with and without asymmetrical glare by using red, green, and yellow filters and ETDRS chart and E-chart. Results: In both light conditions of with and without glare, the mean visual acuity of the three filters in the right and left eyes was significantly better with the E-chart versus the ETDRS chart (P

Purpose: To determine the short-term effect of rigid gas permeable (RGP) contact lenses on corneal aberrations in keratoconic patients. Method: Sixteen keratoconic eyes with no history of RGP lens wear were included. They all had corneal aberrometry using Pentacam, and different aberration indices of the anterior and posterior surfaces of the cornea were measured before and 3 months after fitting RGP lenses. The effect of baseline parameters on these changes was tested in univariate and multiple models. Results: Total aberrations and individual Zernike coefficients did not show statistically significant changes after using RGP lenses. Although not statistically significant, vertical coma decreased in the anterior (p = 0.073) and posterior surface (p = 0.095). Relationships that remained statistically significant in the multiple model were between baseline central corneal thickness and changes in total higher order aberrations and anterior 4th order astigmatism 0°, and between baseline 2nd order astigmatism 45° and its changes. Conclusion: In this study, corneal aberrations remained unchanged 3 months after wearing RGP contact lens. Further studies with sufficient samples in different groups of keratoconus severity or baseline aberrations are needed to obtain more accurate results.

Measurement of hematological parameters and their reference ranges play an important role in the diagnosis and treatment of many infectious diseases and cancers. However, there are marked differences in the reference ranges between developing and developed countries. The aim of this study was to establish reference ranges of hematological parameters. This cross-sectional study was conducted in patients visiting Noor Eye Hospital who had no systemic diseases. In the lying position, blood samples were collected in two test tubes (Becton Dickinson Ltd, UK) using the Venoject method. EDTA-containing blood samples were used for complete blood count and differential leukocyte count using a cell counter (Nihdon Kohden Celltac E, Japan). Descriptive statistics, t-test, and ANOVA were used for data analysis. The data of 46,595 individuals were analyzed of whom 47.3% (n=22,042) were men. The mean (95% confidence interval) of white blood cells (WBC), red blood cells (RBC), platelet, and Hemoglobin (Hb) was 6.68 (6.66-6.69), 4.83 (4.83-4.84), 238.40 (237.87-238.93), and 14.29 (14.27-14.30), respectively. There was no difference in hematological parameters between male and female subjects. Except for the platelet count that was higher in individuals below 18 years than those 18-64 years and ≥65 years, other parameters had no relationship with age. Normal values of hematological parameters in the Iranian population are similar to the Middle East and African countries but below standard reference values. Except for the platelet count that decreased with age, there was no significant difference in hematologic and immunologic parameters between age and sex groups. Considering the difference between our results and standard reference values, we suggest that normal values be determined locally for each country.

Purpose: To determine the effect of the cyclopentolate 1% on the cylindrical and spherical components of the refraction. Methods: Three hundred seventy-five eyes of 195 subjects, including 74 males and 121 females, aged from 3 to 59 years were refracted before and 30 min after cyclopentolate 1% eye drop instillation. To compare cylindrical data, power vector analysis (J0 and J45 cross cylinder) was applied. Results: A statistically significant difference between the J0 values of the noncycloplegic and cycloplegic refraction was revealed (P = 0.006) while the J45 values did not significantly differ. 95% limit of agreement for dry and cycloplegic values of the J0 and J45 were −0.22 to 0.25 and −0.19 to 0.20, respectively. Astigmatism difference was separately analyzed in emmetropic, myopic and hyperopic eyes. The J0 difference was significant (P = 0.014) only in hyperopic eyes. Spherical equivalent (SE) values in cycloplegic refraction were significantly more hyperopic than those yielded in dry refraction by mean difference of +1.16 ± 1.20 diopters (P