abbasali yekta

The present study sets out to investigate the effect of cyclopentolateinduced cycloplegia on distance and near deviation and the accommodative convergence/accommodation (AC/A) ratio.

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.

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.

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.

To determine the long-term effects of night shift work on dry eye in hospital nurses.

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.

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).

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.

To determine the prevalence of different types of ocular trauma and their relationship with some factors in the elderly population.

The present population‑based cross‑sectional study was conducted on the elderly population aged 60 years and above in Tehran, Iran, using multi‑stage stratified random cluster sampling in 2019. After selecting the samples and their participation in the study, demographic information and history of ocular trauma were obtained through an interview. Psychological evaluation was performed using the Goldberg’s 28‑question General Health Questionnaire. All study participants underwent optometric and ophthalmological examinations.

Three thousand three hundred and ten people participated in the study (response rate: 87.3%). Of these, 1912 individuals (57.8%) were female and the mean age of individuals was 68.25 ± 6.55 (from 60 to 97) years. 7.46% (95% confidence interval [CI]: 6.51–8.41) of the study participants reported a history of ocular trauma. Blunt and chemical traumas were the most and the least common types of ocular trauma, respectively (5.72% and 0.16%). 3.93% of cases visited an ophthalmologist for ocular trauma, 1.67% reported a history of hospitalization, and 1.47% underwent surgery. The prevalence of visual impairment in individuals with a history of ocular trauma was 12.53%. Visual impairment was more prevalent in people with a history of ocular trauma than those without a history of ocular trauma (P < 0.05). History of ocular trauma was only significantly related to low education level (odds ratio = 0.63, 95% CI = 0.40–0.99). Participants with a history of ocular trauma had more anxiety and higher mean psychological distress score than those without a history of ocular trauma (P = 0.035).

The development of preventive programs against the occurrence of ocular trauma can play an important role in reducing the psychological damage of affected patients while reducing visual disorders. These interventions should be especially considered in groups with a lower education level.

Assessment of the pattern visual evoked potential (PVEP) responses in different areas of visual fields in individuals with normal vision.

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.

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.

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.

To determine the distribution of corneal biomechanical parameters in an elderly population.

This cross‑sectional study was conducted in subjects above 60 years living in Tehran. The participants were selected using multi‑stage cluster sampling. Corneal biomechanical parameters were measured in a randomly selected subsample of this population using the Reichert Ocular Response Analyzer (Reichert Ophthalmic Instruments, Inc., Buffalo, NY, USA).

Of 470 subjects, the data of 420 participants aged over 60 years were analyzed (mean age: 69.3 ± 6.5 years and range: 61–88 years), 363 (86.4%) of whom were male. The mean and standard deviation of corneal hysteresis (CH) and corneal resistance factor (CRF) were 8.37 ± 1.55 mmHg (95% confidence interval [CI]: 8.02–8.72) and 9.06 ± 1.70 mmHg (95% CI: 8.69–9.44), respectively. The mean CH was 8.27 ± 1.54 mmHg in men and 9.25 ± 1.28 mmHg in women, and the mean CRF was 9.00 ± 1.71 mmHg in men and 9.63 ± 1.37 mmHg in women. According to the results of multiple linear logistic regression analysis, CH had a significant association with younger age (β = −0.05, P = 0.032), female sex (β = 1.83, P < 0.001), reduced maximum keratometry (β = −0.22, P = 0.06), and increased anterior chamber volume (β = 0.01, P = 0.007). CRF had a significant correlation with a younger age (β = −0.06, P = 0.02), female sex (β = 1.01, P = 0.05), central corneal thickness (β = 0.02, P < 0.001), and reduced maximum keratometry (β = −0.39, P = 0.010).

The mean CH and CRF values were low in this sample of the Iranian population aged over 60 years indicating the weaker elasticity of the corneal connective tissue.

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<0.05). The mean CCT was 531.19 µ (±34.88 µ) and 540.66 µ (±27.13 µ) in the DE and NDE group, respectively. Based on linear regression analysis, ISV, IVA, IHA, and IHD had a significant association with DED (P<0.05), while CCT had no significant association with DED (P=0.148). DED significantly increases corneal surface irregularity, but it has no significant effects on CCT measured by the Pentacam.

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.

To determine the relationship between road accidents with visual acuity, refractive errors, visual field, and contrast sensitivity.

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.

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).

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.

To evaluate varied aspects of binocular function in multiple gaze positions.

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 crosssectional 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.

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).

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.

Purpose: To determine the global prevalence and common causes of visual impairment (VI) and blindness in children. Methods: In this meta-analysis, a structured search strategy was applied to search electronic databases including PubMed, Scopus, and Web of Science, as well as the list of references in the selected articles to identify all population-based cross-sectional studies that concerned the prevalence of VI and blindness in populations under 20 years of age up to January 2018, regardless of the publication date and language, gender, region of residence, or race. VI was reported based on presenting visual acuity (PVA), uncorrected visual acuity (UCVA), and best corrected visual acuity (BCVA) of equal to 20/60 or worse in the better eye. Blindness was reported as visual acuity worse than 20/400 in the better eye. Results: In the present study, 5711 articles were identified, and the final analyses were done on 80 articles including 769,720 people from twenty‑eight different countries. The prevalence of VI based on UCVA was 7.26% (95% confidence interval [CI]: 4.34%–10.19%), PVA was 3.82% (95% CI: 2.06%–5.57%), BCVA was 1.67% (95% CI 0.97%–2.37%), and blindness was 0.17% (95% CI: 0.13%–0.21%). Refractive errors were the most common cause of VI in the subjects of selected articles(77.20% [95% CI: 73.40%–81.00%]). The prevalence of amblyopia was 7.60% (95% CI: 05.60%–09.10%) and congenital cataract was 0.60% (95% CI: 0.3%–0.9%). Conclusion: Despite differences in the definition of VI and blindness, based on PVA, 3.82%, and based on BCVA, 1.67% of the examined samples suffer from VI.

We aimedto determine the age and sex standardized prevalence of corneal opacity and its de-terminants

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.

The 3310 participated in the study, of whom the data of 3284 were analyzed. The age and sex stand-ardized 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), re-spectively. The mean uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) according to LogMar were worse in subjects with corneal opacity (both P<0.001). According to multiple logistic regression analysis, male sex (OR: 1.98; P: 0.003), age>80 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).

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 andimproving 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.

To simplify the fitting process, this study was designed to predict the initial power of contact lenses using the regression model based on manual Javal keratometry data and refractive errors.

In this retrospective study, 121 eyes of 69 patients with keratoconus(KCN) were fitted with a specific trial set of rigid gas permeable contact lenses based on the standard criterion of “three‑point touch” over a 7‑year period. Power of the cornea was measured using Javal keratometer. Refractive errors and over refraction of patients were diagnosed using Topcon autorefractometer (RM‑A2000) and confirmed by Heine beta 2000 retinoscope.

The results of multiple linear regression showed the following equation: power of contact lens = −14.368 (constant of the final multiple regression model), +0.475 (spherical refraction), and +0.275 (flatter corneal power).

The results of this study revealed that lens power has a significant relationship with the power of the flat corneal meridian and spherical refractive error in KCN patients. The obtained regression model can be used to shorten patients’ chair time and optometric examination for predicting the power of contact lens.

To determine and compare ocular characteristics and refractive errors between thalassemia major patients and normal subjects.

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.

The results showed that the mean UCVA was better in the control group versus the thalassemia group (p<0.001) while there was no difference in BCVA between the two groups (p=0.416). Moreover, the mean spherical equivalent was 0.38±0.13 D less in the thalassemia group compared to the control group (p=0.007) while corneal power (p<0.001) and cylinder power (p=0.001) were larger in thalassemia patients. Most common type of astigmatism was against the rule pattern in thalassemia patients and with the rule pattern in the control group (p<0.001). The mean tear break-up time was 11.35 ± 6.43 in the thalassemia group and 14.63 ± 5.79 in the control group (p=0.001), and the mean near point of accommodation (NPA) (p=0.009) and near point of convergence (NPC). (p=0.003) were significantly smaller in the thalassemia group compared to the control group.

These patients suffer from a myopic shift due to exaggerated responses to changes in ocular growth, dry eye secondary to goblet cell loss, and a higher prevalence of vertical astigmatism due to eyelid laxity and pressure on the cornea. Therefore, regular ophthalmological evaluations are highly recommended in these patients.

To determine the prevalence of fusional vergence dysfunction (FVD) and its relationship with age, sex, and refractive errors in a population-based study.

In this cross-sectional study, all residents of Mashhad, northeast of Iran, aged >1 year were subjected to random stratified cluster sampling. After selecting the participants, they all underwent complete optometric examinations including the measurement of visual acuity and refraction, assessment of binocular vision and accommodative status, and slit-lamp biomicroscopy.

Of 4453 invited individuals, 3132 participated in the study. After applying the exclusion criteria, statistical analysis was performed on the data of 1683 participants. The prevalence of FVD was 3.2% in all participants, 4.0% in men, and 2.9% in women (P = 0.234). The prevalence of FVD increased linearly with aging from 2.3% in the age group of 10–19 years to 5.4% in the age group of 40–49 years (P = 0.034). The prevalence of myopia, hyperopia, and emmetropia was 11.1%, 29.6%, and 59.3% in participants with FVD and 16.7%, 26.4%, and 57% in participants without FVD, respectively (P = 0.570). Multiple logistic regression analysis only showed a significant association between age and FVD (odds ratio =1.03 95% confidence interval: 1.02–1.05, P = 0.031).

The prevalence of FVD in this study was higher than most previous reports and increased significantly with aging. FVD had no significant association with sex and refractive errors.

To determine economic inequality in visual impairment (VI) and its determinants in the rural population of Iran.

In this population‑based, cross‑sectional study, 3850 individuals, aged 3–93 years were selected from the north and southwest regions of Iran using multi‑staged stratified cluster random sampling. The outcome was VI, measured in 20 feet. Economic status was constructed using principal component analysis on home assets. The concentration index (C) was used to determine inequality, and the gap between low and high economic groups was decomposed to explained and unexplained portions using the Oaxaca–Blinder decomposition method.

Of the 3850 individuals that were invited, 3314 participated in the study. The data of 3095 participants were finally analyzed. The C was −0.248 (95% confidence interval [CI]: −0.347 - −0.148), indicating a pro‑poor inequality (concentration of VI in low economic group). The prevalence (95% CI) of VI was 1.72% (0.92–2.52) in the high economic group and 10.66% (8.84–12.48) in the low economic group with a gap of 8.94% (6.95–10.93) between the two groups. The explained and unexplained portions comprised 67.22% and 32.77% of the gap, respectively. Among the study variables, age (13.98%) and economic status (80.70%) were significant determinants of inequality in the explained portion. The variables of education (coefficient: −4.41; P < 0.001), age (coefficient: 14.09; P < 0.001), living place (coefficient: 6.96; P: 0.006), and economic status (coefficient: −7.37; P < 0.001) had significant effects on inequality in the unexplained portion.

The result showed that VI had a higher concentration in the low economic group, and the major contributor of this inequality was economic status. Therefore, policymakers should formulate appropriate interventions to improve the economic status and alleviate economic inequality.

To determine the distribution of keratometry values in a wide age range of 6-90 years.

In this cross-sectional study, samples were selected from two villages in Iran using multi-stage random cluster sampling. After completing optometry and ophthalmic examinations for all cases, corneal imaging was done using Pentacam, and keratometry values were determined.

Of the 3851 selected people, 3314 people participated in the study, and after applying the exclusion criteria, analyses were done on data from 2672 people. Mean age of the participants was 36.30 ± 18.51 years (from 6 to 90 years). Mean keratometry (mean‑K) in flat and steep meridians was 42.98 (42.9‑43.06) diopters (D) and 43.98 (43.91‑44.07) D, respectively. Average of mean‑K was 43.48 (43.41‑43.56) D. Mean‑K increased linearly up to the age of 70 years, and the cornea became slightly flat afterwards (coefficient = 0.01; P < 0.001). Mean‑K was significantly higher in females (P < 0.001). Myopic cases had the highest mean‑K (P < 0.001). The correlation of mean‑K with age, gender, central corneal thickness, anterior chamber depth, pupil diameter, and spherical equivalent was investigated in a multiple regression model. Only older age and female gender showed a statistically significant association with mean‑K. Overall, 31.62% (29.14‑34.09) of the sample in this study had at least 1.0 D of corneal astigmatism.

This is one of the few studies worldwide that demonstrates changes in keratometry in a wide age range from childhood to old age. Results indicated that age and gender are variables associated with keratometry

To determine the distribution of residual and corneal astigmatism (CA) in children aged 6–18 years and their relationship with age, sex, spherical equivalent, and biometric parameters.

In this cross‑sectional study, multi‑stage stratified cluster sampling was done to select students from Dezful, a city in Southwestern Iran. Examinations included the measurement of visual acuity with and without optical correction, refraction with and without cycloplegia, and biometry using the Biograph (Lenstar, Germany). The main outcomes in this report were corneal and residual astigmatism. The CA was measured by Biograph (difference between k1 and k2), and residual astigmatism was calculated using Alpine method. The power vector method was applied to analyze the data of astigmatism.

Of 864 students that were selected, 683 (79.1%) participated in the study. The mean residual and CA were −0.84 diopter (D) and −0.85 D, respectively. According to the results of J0 and J45 vectors, residual astigmatism was −0.33 D and 0.04 D, and CA was 0.38 D and 0.01 D, respectively. With‑the‑rule (WTR), against‑the‑rule (ATR), and oblique astigmatism were seen in 3.4%, 66.8%, and 4.5% of the children with residual astigmatism and 67.94%, 1.3%, and 1.5% of the children with CA. Residual astigmatism decreased with an increase in spherical refractive error, whereas CA increased with an increase in spherical refractive error.

The results of the present study showed a high prevalence and amount of residual astigmatism with ATR pattern among the 6–18‑year‑old population and the compensatory effect of this type of astigmatism on CA that mostly followed a WTR pattern.

To determine the distribution of keratoconus indices in a 5‑93‑year‑old healthy eyes of a rural population in Iran.

In this cross-sectional study, multi-stage cluster sampling was applied to select subjects from two villages in the north and southwest of Iran. After obtaining informed consent, all subjects underwent ophthalmologic and optometric examinations. Corneal imaging by the Pentacam was done in subjects above 5 years between 9 a.m. and 2 p.m., at least 3 h after wakeup. All subjects who had abnormal keratoconus indices were excluded. Our main outcome was keratometry‑flat (Kf ), keratometry-steep (Ks ), keratoconus index (KI), and central keratoconus index (CKI).

The mean ± standard deviation of Kf , Ks , KI, and CKI was 43.12 ± 1.74, 44.25 ± 1.65, 1.02 ± 0.02, and 1.01 ± 0.01, respectively. According to multiple linear regression analysis, the mean index surface variance (ISV) (b: ‑1.367, P < 0.001), index vertical asymmetry (IVA) (b: -0.012, P < 0.001), KI (b: -0.011, P < 0.001), CKI (b: -0.001, P < 0.001), index height asymmetry (IHA) (b: -0.491, P: 0.005), and index height decentration (IHD) (b: -0.001, P < 0.001) were lower in men compared to women. Moreover, age had an indirect association with ISV(b: ‑0.030, P < 0.001) and average pachymetric progression index (RPI_avg) (b: ‑0.001, P < 0.001), and a direct association with KI, CKI, and IHA. Spherical equivalence had an indirect association with KI (b: -0.001, P < 0.001) and RPI_avg (b: ‑0.004, P < 0.001) and a direct association with CKI (b: 0.001, P < 0.001). Among all variables, sex had the greatest impact on ISV, IVA, KI, IHA, IHD, and minimum sagittal curvature.

The Keratoconus indices of our study were similar to other studies. Although age, living place, and type of refractive error were associated with some indices, sex was the strongest determinant of Keratoconus indices in a population of healthy eyes.

To determine the distribution of vertical cup-to-disc ratio (VCDR) and its relationship with ocular biometric indices.

This study was conducted in 4737 individuals aged 45-69 years living in Shahroud who participated in the second phase of Shahroud Eye Cohort Study in 2014. All participants underwent eye examinations including the measurement of visual acuity and refraction, slit-lamp biomicroscopy, retinal examination, and fundoscopy. Normality index was used to describe data distribution, and a multiple beta regression, with adjustment for the effect of cluster sampling, was applied to explore the relationship between VCDR and the study variables.

The mean [95% confidence interval (CI)] VCDR was 0.297 (0.293-0.301) in all participants; 0.296 (0.291-0.302) in men and 0.297 (0.292-0.302) in women. The highest mean VCDR was seen in the age group 55-59 years (0.299, 95% CI: 0.292-0.307). The 97.5th percentile was 0.600. According to multiple beta regression analysis, VCDR had a positive association with the female sex (P = 0.028), spherical equivalent (P < 0.001), cigarette smoking (P = 0.020), and axial length (P < 0.001), and had a negative association with hypertension (P = 0.001), best corrected visual acuity (P < 0.001), hyperlipidemia (P = 0.029) and anterior chamber depth (P = 0.001).

The mean VCDR and the 97.5th percentile were lower than most other studies. Although ethnicity and race may play a role in this difference, this difference should be considered in clinical decisions in the current population.

To review current non-surgical management methods of intermittent exotropia (IXT) which is one of the most common types of childhood-onset exotropia.

Asearch strategy was developed using a combination of the words IXT, divergence excess, non-surgical management, observation, overcorrecting minus lens therapy, patch/occlusion therapy, orthoptics/binocular vision therapy, and prism therapy to identify all articles in four electronic databases (PubMed, Web of Science, Google Scholar, and Scopus). To find more articles and to ensure that the databases were thoroughly searched, the reference lists of the selected articles were also reviewed from inception to June 2018 with no restrictions and filters.

IXT is treated when binocular vision is impaired, or the patient is symptomatic. There are different surgical and non-surgical management strategies. Non-surgical treatment of IXT includes patch therapy, prism therapy, orthoptic sessions, and overcorrecting minus lens therapy. The objective of these treatments is to reduce the symptoms and the frequency of manifest deviation by decreasing the angle of deviation or enhancing the ability to control it.

Evidence of the efficacy of non-surgical management options for IXT is not compelling. More comprehensive randomized controlled trial studies are required to evaluate the effectiveness of these procedures and detect the most effective strategy

To determine the prevalence of ptosis and nystagmus in the general rural population in Iran.

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.

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).

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.

To determine economic inequality in unmet refractive error (RE) need and its determinants in deprived rural population of Iran.

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.

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.

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.

To review the published data about changes in the anterior chamber depth (ACD) in keratoconus patients.

In this systematic review and meta-analysis of observational studies, we reviewed the available and relevant literature on anterior segment changes in keratoconic eyes, with a special focus on the ACD, an effective factor in many surgical methods. Articles published up to December 2017 were identified in the following data sources: PubMed, Scopus, Ovid, ISI, ScienceDirect, and Google Scholar. Databases were comprehensively searched using the key words “Anterior Chamber Depth AND Anterior segment AND Keratoconus”.

A total of 496 studies including these key words were detected. Four hundred fifty‑three studies were excluded, and overall 16 studies which precisely described the change in ACD were included in the literature review. The results show that with respect to the applied device, there was a statistically significant difference in ACD between keratoconic eyes and normal eyes except for Galilei analyzer.

Summarizing the results of studies, this review revealed that ACD is significantly deeper in keratoconic eyes as compared with normal eyes, which could be explained by the steeper corneal curvature.