Pakistan Journal of Ophthalmology Vol. 33, No. 3, Jul – Sep, 2017 169 Original Article Prevalence of Astigmatism in School Going Children Rida Ijaz, Hijab Ijaz, Naeem Rustam Pak J Ophthalmol 2017, Vol. 33, No. 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See end of article for authors affiliations …..……………………….. Correspondence to: Rida Ijaz Department of Ophthalmology, Email:rida_2693@hotmail.com …..……………………….. Purpose: To assess the prevalence of astigmatism, and most common type of astigmatism among school going children. Study Design: Cross sectional observational study. Place and Duration of Study: City District Govt. Girls High School, Shadman and “Department of Ophthalmology” FMH College of Medicine & Dentistry, Shadman Lahore from September 2014to February 2015. Materials and Methods: After taking consent data was collected through a self- design performa at City District Govt. Girls High School, Shadman Lahore from 550 students. Each eye was considered as a separate individual data. Total 1098 eyes were taken for the study, age ranges 5 – 16 years. First visual acuity was measured monocularly by using snellen’s visual acuity chart. In case of substandard vision, pinhole test was done to assess the maximum improvement after correction. Amount and type of astigmatism was assessed by using cycloplegic refraction. Eyes with amblyopia, strabismus or other ocular pathologies were excluded. Result: We examined 1098 eyes of the 550 students, with mean age of 10.31 ± 3.276 years including 255 (46.4%) male students and 295 (53.6%) female students. Astigmatism was seen in 818 eyes (74.5%), out of which 0.5 – 1.00 diopter cylinder was the most common and was present in 454 eyes (41.3%), With the rule astigmatism was seen in 605 eyes (55.1%) and 355 (32.3%) had compound myopic astigmatism. Conclusion: With the rule astigmatism and compound myopic astigmatism are more common among males and females and maximum in the age group of 14 – 16 years of age. Key words: Amblyopia, Astigmatism, Children, Refractive error. stigmatism is refractive error in which the parallel rays of light coming from 6 meters entering the eye through the refractive medium do not focus on a single sharp point on the retina1. In astigmatism light rays do not refract equally in all meridians and do not focus equally in all meridians. Due to unequal focusing, light comes to focus along a line instead of a point (astigma= no Point) 2. Corneal dioptric power is 40-45 D and lenticular power is little less than 20 D3. The average diameter of the cornea is 11 – 12mm (horizontal = 12mm, vertical = 11mm)4. Cornea is more curved vertically due to pressure of the lids. Increased curvature results in physiological myopic astigmatism of 0.5D in horizontal axis5. Astigmatism changes relatively little during much of the life span tending to change towards against the rule astigmatism in the later years6. Astigmatism is diagnosed by retinoscopy, which is objective method to assess refractive status of the eye7. A RIDA IJAZ, et al 170 Vol. 33, No. 3, Jul – Sep, 2017 Pakistan Journal of Ophthalmology Severe degree of astigmatism can be caused by diseases of cornea e.g. keratoconus and late effects of scarring from wound such as corneal incision following cataract surgery8. Astigmatism can cause visual impairment in children, but it can be corrected9. MATERIALS & METHODS This was a cross sectional observational study. The study was conducted in six months from September 2014 to February 2015. After taking ethical approval from the hospital and school data was collected and it was only for research purpose. After taking consent from student’s data was collected through a self- design performa at city district govt. girl’s high school, shadman Lahore from 550 students sample size was calculated by using formula of Sample Size= Z1-a/22 SD2/d2 First visual acuity was assessed by using Snellen’s visual acuity chart with patient seated at distance of 6 meters. If visual acuity was less than 6/6, which is the standard line of this chart then pinhole test was done. If vision improved to 6/6 in this test then the patients were considered to have refractive error. Total refractive error was calculated using a retinoscope. For retinoscopy, patient’s pupil were dilated with cycloplegic drug i.e. 1% cyclopean three times with the interval of 10 minutes and retinoscopic reflex was noted after 90 minutes of instillation of first drop. By this method, type and amount of refractive error was calculated. Patients whose eyes had amblyopia, strabismus or other ocular pathologies were excluded from this study. RESULTS In this study, there were 1098 eyes of 550 students with their mean ages were 10.31 ± 3.276 (range: 5 – 16 years) years. For study purpose it was stratified into four groups (5 – 7, 8 – 10, 11 – 13, 14 – 16 years) as shown in table 1 including 509 eyes of 255 (46.4%) male students and 589 eyes of 295 (53.6%) female students. From the total 1098 eyes having refractive error, only 280 eyes (25.5%) had no astigmatism and 818 eyes (74.5%) had astigmatism details of which are given in table 2. In this study, with the rule astigmatism was most commonly found in 605 eyes (55.1%) in which vertical meridian of cornea or lens is steeper than horizontal while least frequent astigmatism was against the rule which was found in 100 eyes (9.1%) of students and remaining 113 eyes (10.3%) had oblique astigmatism. Compound myopic astigmatism 355 (32.3%) was more commonly present in students in both males and females eyes Simple myopic astigmatism was seen in 151 (13.8%) eyes, mixed astigmatism was present in 92 (8.4%) eyes and compound hypermetropic astigmatism in 152 eyes (13.8%) of students. Least common type of astigmatism was simple hypermetropic astigmatism that was seen in only 69 (6.3%) eyes of both males and females. Using multinominal logistic regression analysis results found that mixed astigmatism belongs to reference category. Students having age group range of 14 – 16 years are more likely to be non-astigmatic than mixed astigmatism as compared to other age groups. Students having age group range of 14 – 16 years are most probable to have simple myopic Table 1: Age of Patient Vs Type of Astigmatism Age of Patient 5 – 7 Years 8 – 10 Years 11 – 13 Years 14 – 6 Years Total Type of Astigmatism according to Power meridian (p- value=0.00) No Astigmatism 44 78 80 78 280 Myopic Astigmatism 75 132 122 130 459 Hypermetropic Astigmatism 71 85 27 13 196 Mixed Astigmatism 60 56 35 12 163 Total 250 351 264 233 1098 PREVALENCE OF ASTIGMATISM IN SCHOOL GOING CHILDREN Pakistan Journal of Ophthalmology Vol. 33, No. 3, Jul – Sep, 2017 171 Type of Astigmatism according to Axis meridian (p- value=0.00) No Astigmatism 44 78 80 78 280 With the rule Astigmatism 166 211 125 103 605 Against the Rule Astigmatism 20 34 25 21 100 Oblique Astigmatism 20 28 34 31 113 Total 250 351 264 233 1098 Table 2: Amount of Astigmatism. Amount of Astigmatism 0.0 0.50-1.00DC 1.25-2.00DC 2.25-3.00DC 3.25-4.00DC >4.00DC No. of eyes 280 eye (25.5%) 454 eyes (41.3%) 179 eyes (16.3%) 99 eyes (9.0%) 48 eyes (4.4%) 38 eyes (3.5%) p-Value= 0.00 astigmatism and compound myopic astigmatism than mixed astigmatism as compared to other age groups. Students belonging to age group range of 14-16 years are more prone to have simple hypermetropic astigmatism than mixed astigmatism as compared to students who have age groups of 11 – 13 years. There is no significant result found in logistic regression in different age groups in compound hypermetric astigmatism than mixed astigmatism as shown in table 3. Similarly oblique astigmatism was found to be a reference category and we found that students in age groups range of 5 – 7 years and 8 – 10 years are more likely to have with the rule astigmatism than oblique astigmatism as compared to the age group of 14 – 16 years and there is no significant result found in any age group for against the rule astigmatism and those who have no astigmatism as shown in table 4. Table 3: Type of Astigmatism According to Power Meridiana Predictor Value No Astigmatism Simple Myopic astigmatism Simple Hypermetropic astigmatism Compound Myopic astigmatism Compound Hypermetropic astigmatism B 95% CI B 95% CI B 95% CI B 95% CI B 95% CI 5 – 7 Years -2.60*** 0.02- 2.02 -1.79*** 0.05- 0.47 -0.93 0.11- 1.34 -2.70*** 0.02- 0.18 -0.13 0.26-2.87 8 – 10 Years -1.64** 0.07- 0.52 -1.26** 0.09- 0.81 -0.36 0.20- 2.40 -1.63*** 0.07- 0.52 0.50 0.49-5.53 11 – 13 Years -1.51** 0.08- 0.60 -1.26** 0.09- 0.83 -1.52* 0.05- 0.86 -1.63*** 0.07- 0.53 -0.51 0.16-2.11 14 – 16 Years Ref.+ - Ref.+ - Ref.+ - Ref.+ - Ref.+ - a. The reference category is: Mixed astigmatism. + Reference RIDA IJAZ, et al 172 Vol. 33, No. 3, Jul – Sep, 2017 Pakistan Journal of Ophthalmology Table 4: Type of Astigmatism According to Axis Meridiana Predictor Value No Astigmatism With the rule Astigmatism Against the Atigmatism B 95% CI B 95% CI B 95% CI 5-7 Years -0.15 0.43-1.68 0.89** 1.31-4.53 0.38 0.63- 3.38 8-10 Years 0.08 0.59-1.98 0.79** 1.26-3.91 0.57 0.83-3.77 11-13 Years -0.08 0.51-1.64 0.08 0.62-1.89 0.07 0.50-2.30 14-16 Years Reference - Reference - Reference - a. The reference category is: Oblique astigmatism. DISCUSSION Astigmatism can occur in any age group, children and adults. Previous studies have suggested that uncorrected astigmatism is associated with increased risk of myopia or amblyopia. Early detection of astigmatism in pediatric populations is particularly important because of its potential influence on normal visual development10, 11. In this study, there was no relationship between gender and type of astigmatism according to axis and meridian in the above conducted study. And in study of China, there was also no significant difference in the occurrence of astigmatism between boys and girls12. Amount of astigmatism does not change much after the age of 25. The changes in the shape of the cornea can happen quickly or may occur over several years.13 If astigmatism is left untreated in children then it can cause meridional amblyopia14. Corneal topography is a valuable diagnostic tool for diagnosing subclinical keratoconus and for tracking the progression of the disease13. It is shown that, 280 eyes (25.5%) had no astigmatism, but 605 eyes (55.1%) had with the rule astigmatism, 100 eyes (9.1%) had against the rule astigmatism and 113 eyes (10.3%) had oblique astigmatism. In this study, there was simple myopic astigmatism in 151 (13.8%), compound myopic astigmatism in 355 (32.3%) students while mixed astigmatism in 92 (8.4%) students. In others simple hypermetropic astigmatism was in 69 (6.3%) and compound hypermetropic astigmatism was seen in 152 (13.8%) students. While in a study conducted in Taiwan, 42.5% of school children had astigmatism. Most of them (80%) had -1.0 D while 60% of them had myopic astigmatism15. Of the 914 eyes with astigmatism, myopic astigmatism was present in 700 eyes (76.60%), hypermetropic astigmatism in 175 eyes (19.14%), and mixed astigmatism in 39 eyes (4.26%)16. A study held in Canada in 2004 on preschool children included 129 children for their study. Of the 129 subjects, 29 were classified as high astigmatism (-1 D of cylinder) in one or both eyes and the other 100 subjects were classified as normal astigmats17. A study held on Native Americans in 2010 included 1502 children. According to results, the prevalence of astigmatism of 2.00 diopters was 30% during infancy (6 months to 1 year of age) and was 23 to 29% in ages 2 to 7 years18. Astigmatism can be treated by anyone of the following options; eye glasses, contact lenses and refractive surgery19. In refractive surgery corneal curvature is altered to change the focusing of the light rays on retina. Radial keratotomy and photorefractive surgery are examples of refractive surgeries20. CONCLUSION With the rule astigmatism and compound myopic astigmatism are more common among males and females and maximum in the age group of 14-16 years of age. If it is not treated timely then it will leads to amblyopia. Therefore, proper screening can prevent a child from permanent visual loss due to amblyopia. Author’s Affiliation Dr. Rida Ijaz BSC Hons Optometry and orthoptics, Transitional Doctor of Optometry Lecturer Dept of optometry & vision sciences/ Imperial college of business studies Lahore Dr. Hijab Ijaz PREVALENCE OF ASTIGMATISM IN SCHOOL GOING CHILDREN Pakistan Journal of Ophthalmology Vol. 33, No. 3, Jul – Sep, 2017 173 BSC Hons Optometry and orthoptics, Transitional Doctor of Optometry Senior Lecturer Dept of optometry & vision sciences/ The university of Lahore Dr. Naeem Rustam FCPS, MBBS, Assistant professor Dept of optometry & orthoptics/FMH college of medicine & Dentistry Lahore Role of Authors Dr. Rida Ijaz Concept, Design of study, data collection, data analysis, manuscript drafting, Revision data analysis. Dr. Hijab Ijaz Data collection, manuscript drafting. Dr. Naeem Rustam Manuscript drafting, Revision data analysis. REFERENCES 1. Abbasi S, Imtiaz A, Shah AR, Quratulain Zamir. Frequency of amount and axis of astigmatism in subjects of Rawalpindi, Pakistan. 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