Non-surgical Management Options of Intermittent Exotropia: A Literature Review.

PURPOSE: To review current non-surgical management methods of intermittent exotropia (IXT) which is one of the most common types of childhood-onset exotropia. METHODS: A search 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. RESULTS: 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. CONCLUSIONS: 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.

Stereoacuity after Wavefront-guided Photorefractive Keratectomy in Anisometropia.

PURPOSE: To determine changes in stereoacuity in anisometropic myopic eyes after photorefractive keratectomy (PRK). METHODS: Myopic patients with at least 1 diopter (D) of anisometropia in sphere, astigmatism, or spherical equivalent who were referred to our hospital for excimer refractive surgery were enrolled as a prospective sequential interventional case series. All patients underwent wavefront-guided photorefractive keratectomy (WFG-PRK) using the Technolas Perfect Vision (217z) Excimer laser machine. Changes in binocular stereoacuity were evaluated using the TNO and Butterfly stereoacuity tests before and at 2 weeks, 1 month, and 3 months after the operation. RESULTS: Between January and November 2015, a total of 98 eyes of 49 patients (71.4% men) with a mean age of 28 ± 5.5 years, mean myopia of -3.32 ± 1.74 D, and mean astigmatism of 1.3 ± 1.3 D were enrolled in this study. Preoperative mean stereoacuity values were 102 ± 103.44 and 56.8 ± 41 seconds of arc (s/arc)as measured by the TNO and Butterfly stereoacuity tests. Mean stereoacuity improved to 90 ± 110.52 s/arc (P = 0.009) and 56.5 ± 41.3 s/arc (P = 0.80), respectively, 6 months after WFG-PRK. Overall improvement in stereoacuity was 10.2% and 6.12% according to the TNO and Butterfly stereoacuity tests, respectively. CONCLUSION: Stereoacuity improves after WFG-PRK for treatment of anisometropic myopia. This improvement is more accurately detectable by the TNO than the Butterfly stereoacuity test.

The Prevalence of Amblyopia, Strabismus, and Ptosis in Schoolchildren of Dezful.

Purpose To determine the prevalence of amblyopia, strabismus, and ptosis among schoolchildren in Dezful in the west of Iran. Methods In this cross-sectional study, 1,375 schoolchildren of Dezful were selected through multistage cluster sampling. After obtaining written consents, participants had uncorrected and corrected visual acuity tests, cycloplegic refraction, and the cover test, and were examined for ptosis at the school site. Results Of the 1,151 study participants (83.7%), examinations were completed for 1,130 schoolchildren. Prevalence rates of amblyopia, strabismus, and ptosis were 2.7% (95% confidence interval [CI] 0.8-4.7), 1.9% (95% CI: 0.2-3.8), and 0.8%, respectively. Anisometropia was the most common cause of amblyopia; 45.2% of cases had anisometropic amblyopia. Among cases with strabismus, 63.6% were exotropic and 36.4% were esotropic. Conclusion The present study indicated that the prevalence of amblyopia and strabismus in Dezful schoolchildren falls in the average range. Since the Amblyopia Screening Program has been running for years, we expected lower rates compared to previous years, but this was not observed. Correcting refractive errors can significantly reduce amblyopic cases.

Estimation of the hybrid lens parameters through rigid gas permeable lens fitting.

PURPOSE: To estimate the fitting parameters of the hybrid contact lens in patients with corneal ectasia using the rigid gas permeable (RGP) lens. METHODS: Thirty-four eyes with corneal ectasia were evaluated in this study. The patients were examined once with the RGP lens and once with the hybrid contact lens. The relationship between the base curvature of the RGP and the vault of the hybrid lens and the correlation between their powers were analyzed. RESULTS: We found a linear relationship between the base curvature of the RGP lens and the vault of the hybrid lens (P < 0.001) (R(2) = 0.45). Moreover, we found a correlation between the power of the RGP and hybrid lens (P < 0.001) (R(2) = 0.4). However, a 0.5 mm decrease in the base curvature radius of the RGP lens increased the vault of the hybrid lens by 72 µ. CONCLUSION: The results of this study could be used for better and faster selection of the first hybrid contact lens.

Cycloplegic autorefraction versus subjective refraction: the Tehran Eye Study.

AIM: To compare cycloplegic autorefraction with non-cycloplegic subjective refraction across all age and refractive error groups. METHODS: In a cross-sectional study with random stratified cluster sampling, 160 clusters were chosen from various districts proportionate to the population of each district in Tehran. Following retinoscopy and autorefraction with the 0.25 D bracketing (Topcon KR-8000, Topcon, Tokyo, Japan), all participants had a subjective refraction. Then all participants underwent cycloplegic autorefraction. RESULTS: The final analysis was performed on 3482 participants with a mean age of 31.7 years (range 5-92 years). Based on cycloplegic and subjective refraction, mean spherical equivalent (SE) was +0.31±1.80 and -0.32±1.61 D, respectively (p<0.001). The 95% limits of agreement (LoA) between these two types of refraction were from -0.40 to 1.70 D. The largest difference between these two types of refraction was seen in the age group of 5-10 years (1.11±0.60 D), and the smallest difference was in the age group of >70 years (0.34±0.45 D). The 95% LoA was -0.52 to 0.89 D in patients with myopia and -0.12 to 2.04 D in patients with hyperopia. We found that female gender (coefficients=0.048), older age (coefficients=-0.247), higher education (coefficients=-0.043) and cycloplegic SE (coefficients=-0.472) significantly correlated with lower intermethod differences. CONCLUSIONS: The cycloplegic refraction is more sensitive than the subjective one to measure refractive error at all age groups especially in children and young adults. The cyclorefraction technique is highly recommended to exactly measure the refractive error in momentous conditions such as refractive surgery, epidemiological researches and amblyopia therapy, especially in hypermetropic eyes and paediatric cases.

Anterior Chamber Angle and Anterior Chamber Volume in a 40- to 64-Year-Old Population.

PURPOSE: To determine the distribution of the anterior chamber angle (ACA) and anterior chamber volume (ACV) in an Iranian population of 40- to 64-year-old people using the Pentacam. METHODS: In this cross-sectional study, multistage sampling was used to select 300 clusters, including 6,311 individuals from the city of Shahroud. All selected participants underwent examinations in one place. Optometric examinations, including measurement of visual acuity and refraction, and ophthalmologic examinations, including slit-lamp examination, were performed for all participants. Moreover, all patients underwent imaging with the Pentacam. RESULTS: The mean ACA and ACV was 34.3° (95% confidence interval [CI]: 34.1°-34.5°) and 139 µL (95% CI: 137.7-140.3), respectively. In a multiple linear regression model, the ACA was inversely correlated with age (coefficient=-0.08), lens thickness (coefficient=-1.38), corneal diameter (coefficient=-0.36), and corneal curvature (coefficient=-1.43), and directly correlated with the anterior chamber depth (ACD) (coefficient=6.59). In another model, ACV was inversely correlated with age (coefficient=-0.37), central corneal thickness (coefficient=-0.04), and spherical equivalent (coefficient=-1.15), and directly correlated with the ACD (coefficient=85.67), lens thickness (coefficient=14.15), corneal diameter (coefficient=4.80), corneal curvature (coefficient=18.43), ACA (coefficient=0.65), and intraocular pressure (coefficient=0.23). CONCLUSION: The findings of this study could be used as a reference for diagnosis and treatment in Iran and the Middle East region. Increase in age and decrease in the ACD were important factors associated with decreased ACA and ACV, although the correlation of other biometric components was also evaluated. Some of these components, such as the corneal curvature and lens thickness, had a significant relationship with these two variables.

The Prevalence of Ptosis and Its Association with Amblyopia and Strabismus in 7-Year-Old Schoolchildren in Iran.

PURPOSE: To determine the prevalence of ptosis (congenital/acquired) in Iranian children aged 7 years and its relationship with amblyopia and strabismus. METHODS: Eight Iranian cities were selected for this cross-sectional study using multistage randomized cluster sampling. A number of primary schools were randomly selected in each city. All grade 1 students in each selected primary school underwent optometric examinations including the measurement of uncorrected and corrected visual acuity, cover test, and cycloplegic and non-cycloplegic refraction. RESULTS: Of 4614 selected students, 4106 students participated in the study (response rate = 89%). The prevalence of ptosis (congenital/acquired) was 1.41% (95% CI 1-1.83); 0.49% (95% CI 0.26-0.72) and 0.93% (95% CI 0.59-1.26) had unilateral and bilateral ptosis, respectively. The prevalence of ptosis had no significant correlation with sex (p = 0.810, OR = 1.07, 95% CI 0.59-1.97). The prevalence of amblyopia was 48.28% and 0.89% in students with and without ptosis, respectively. The prevalence of tropia was significantly higher in cases with bilateral ptosis (p < 0.001). The mean cylinder error was 1.63 ± 1.72 and 0.44 ± 0.60 in ptotic and non-ptotic eyes, respectively (p < 0.001). With-the-rule (WTR) astigmatism was significantly more prevalent in students with ptosis. CONCLUSION: We report the prevalence of ptosis (congenital/acquired) in children in Iran and the Middle East region for the first time. Amblyopia was considerably more prevalent in ptotic patients. We found a significant correlation between ptosis and tropia. Astigmatism, especially WTR stigmatism, was more prevalent in children with ptosis.

The Prevalence and Causes of Visaual Impairment and Blindness in a Rural Population in the North of Iran.

BACKGROUND: Visual impairment is a very important public health problem. In Iran, reports of visual impairment and blindness have been published from the urban population while the prevalence of visual impairment in the rural population has not been reported. The purpose of this study to determine the prevalence and causes of visual impairment, in a rural population in district of based on age and sex. METHODS: In a cross-sectional population-based study, using random cluster sampling, 13 of the 83 villages of Khaf County in the north east of Iran were selected. Eye examinations were performed in a Mobile Eye Clinic (Nooravaran Salamat, 2011) and included optometric examinations such as measuring uncorrected and corrected visual acuity along with non-cycloplegic refraction. RESULTS: The prevalence of visual impairment, low vision, and blindness was 6.3% (95% CI 5.3-7.3), 3.4% (95% CI 2.6-4.1), and 3.0% (95% CI 2.3-3.6), respectively. The prevalence of visual impairment ranged from 1.8% in the participant younger than 20 years of age to 28% in the subjects aged 60 and over (P<0.001). After matching for age, the prevalence of visual impairment and low vision was significantly higher in women. The most prevalent causes of visual impairment were uncorrected refractory error (54.5%) and cataract (17.6%). CONCLUSION: The prevalence of visual impairment was significantly higher in the rural population of this study when compared to previous reports from Iran. It seems that provision of therapeutic facilities like cataract surgery and availability of eyeglasses in villages can considerably reduce the prevalence of visual impairment.

The prevalence of refractive errors in 6- to 15-year-old schoolchildren in Dezful, Iran.

PURPOSE: To determine the prevalence of refractive errors, among 6- to 15-year-old schoolchildren in the city of Dezful in western Iran. METHODS: In this cross-sectional study, 1375 Dezful schoolchildren were selected through multistage cluster sampling. After obtaining written consent, participants had uncorrected and corrected visual acuity tests and cycloplegic refraction at the school site. Refractive errors were defined as myopia [spherical equivalent (SE) -0.5 diopter (D)], hyperopia (SE ≥ 2.0D), and astigmatism (cylinder error > 0.5D). RESULTS: 1151 (83.7%) schoolchildren participated in the study. Of these, 1130 completed their examinations. 21 individuals were excluded because of poor cooperation and contraindication for cycloplegic refraction. Prevalence of myopia, hyperopia, and astigmatism were 14.9% (95% confidence interval (CI): 10.1-19.6), 12.9% (95% CI: 7.2-18.6), and 45.3% (95% CI: 40.3-50.3), respectively. Multiple logistic regression analysis showed an age-related increase in myopia prevalence (p << 0.001) and a decrease in hyperopia prevalence (p << 0.001). There was a higher prevalence of myopia in boys (p<<0.001) and hyperopia in girls (p = 0.007). CONCLUSION: This study showed a considerably high prevalence of refractive errors among the Iranian population of schoolchildren in Dezful in the west of Iran. The prevalence of myopia is considerably high compared to previous studies in Iran and increases with age.