PREVALENCE OF EYE DISORDERS IN CHILDREN PRESENTING IN OUTPATIENT DEPARTMENT WITH ASTHENOPIA

Introduction: Asthenopia is a common complaint in school going children. The magnitude of the problem in our region is not known. 
Methodology: Children (5-18 years) presenting in pediatric and ophthalmology outpatient department with symptoms (defined a proiri) were included in study. Exclusion criteria included BCVA of less than 6/9 in either eye, strabismus, ocular or systemic diseases affecting binocular vision, and using any medication that can impact accommodation or convergence. Previous day 24 hour recall method was used to assess the time spent on various activities. Subsequently, detailed refractive assessment was done. 
Results: A total of 24200 children with age group 5-18 years visited outpatient department. Out of them 520 (2.1%) children had symptoms of asthenopia. The proportion of males (66.6%) was higher than female (33.4%). The proportion of children with asthenopia increased from 21% in 5-9 year group to 45% in 13-18 year group. Tearing and eye pain were the commonest presenting complaints The presence of four or more symptoms was not observed in 5-9 age group. Asthenopic children spend a mean of 4.2 hours/day on screen. 
Conclusion: Asthenopia is common eye complaint in school children. It can interfare in near work, so warrants prompt treatment.


Introduction
Asthenopia is the one of the commonest presenting complains in the outpatient department. Patients usually associate these complaints with refractive errors, although in clinical experience, the diagnosis is otherwise. Patients usually presents in outpatient department with headache, watery, burning or itching eyes, blurred vision, eye ache, dry eye sensation, and double vision. (1-4) Its prevalence has been studied in adults since 1970's. (5,6) Due to increase in screen time the prevalence of asthenopia has increased. (7)(8)(9)(10)(11)(12)(13) The studies evaluating the problem in have showed the prevalence of 19.7% (12.4---26.4%) with majority of children having no visual acuity or refraction problem. (14) Two studies from India have evaluated the problem in children working in factories and found significant in increase in eye strain in these children. (15,16) Very few reports of the disease are available among school going children. In study from Iran prevalence of asthenopia in school children was 62.8% (51.9 to 73.8). (17) The prevalence of the problem in our part of the world is not known. So, all children reporting to the outpatient department of Pediatrics and ophthalmology were evaluated for asthnopia.

Methodology
All children 5-18 years presenting in Pediatrics and Ophthalmology outpatient department with symptoms of asthenopia were included. . Asthenopia was defined as presence of atleast one of the ten symptoms of eye pain, dry eyes, eye swelling, blurred vision, diplopia, foreign body sensation, photophobia, tearing, decreased visual acuity, and difficulty in sustaining visual operations. (18,19) Exclusion criteria included BCVA of less than 6/9 in either eye, strabismus, ocular or systemic diseases affecting binocular vision, and using any medication that can impact accommodation or convergence. The study was conducted from August 2017 to August 2018. A written informed consent was taken from the parents for inclusion into the study.
Baseline demographic data was collected in Performa. Previous day 24 hour recall method was used to assess time spend in hours on screen (screen time includes computer, tablet, laptop, mobile, television), studying in class and looking at blackboard, reading/writing and sports/physical activity Children were first tested 3 times for non-cycloplegic auto-refraction by a skilled operator. In the next stage, all participants were tested for uncorrected visual acuity (UCVA). Then, auto-refraction results were refined through retinoscopy, and trial lenses. For each student, first the right and, then, the left eye was tested. For any case with UCVA worse than 6/9 in either eye, subjective refraction was done and the best corrected visual acuity (BCVA) was recorded. Then, far (6 meters) and near (40 cm) cover tests were done using accommodative targets (a single letter 1 line above acuity threshold) and the alternate cover test with prism bar was carried out to diagnose and measure phoria. In the next stage, the near point of accommodation (NPA) was measured with the Donder push-up method using Royal Air Force Rule (RAF) and near print equivalent to 6/9 VA as accommodative target. The target was slowly moved closer to the child along the midline and he/she was asked to report the first sustained blur. To increase the reliability of the test, the measurement was done 3 times and the average NPA was recorded. The average NPA was, then, converted to amplitude of accommodation (AA) in Diopter. The near point of convergence (NPC) was measured similar to AA; instead, the participant was instructed to report the first sustained diplopia of the target. Again, the NPC was measured 3 times and the average was recorded. The gradient accommodative-convergence / accommodation (AC/A) ratio was determined by remeasurement of near phoria by adding -1.00 minus lenses to subjective refraction and comparing the result with the baseline near. (17) Quantitative variables were expressed as mean ±SD, and whereas qualitative variables were given as numbers and percentage. Data analysis was done using IBM-SPSS v.20 and Microsoft Excel.

Results
A total of 24200 children with age group 5-18 years visited outpatient department. Out of them 520 (2.1%) children had symptoms of asthenopia. Mean age of presentation was 10.1± 3.5 years. The baseline demographic data and degree of asthenopia is summarized in Table 1. Mean spherical equivalent refraction in the total sample was -0.89 ± 2.13 D; it was -0.87 ± 1.28 D and -0.90 ± 1.23 D in females and males, respectively. The proportion of children with asthenopia increased from 21% in 5-9 year group to 45% in 13-18 year group. The presence of four or more symptoms was not observed in 5-9 age group. Table 2 shows the frequency of symptom in these children. Tearing and eye pain were the commonest presenting complaints. Mean time spent by children in various daily activities is shown Table 3. Asthenopic children spend a mean of 4.2 hours/day on screen. Table 4 summarizes mean and standard deviation of AA, NPC, and AC/A ratio in Asthenopic children. Mean (±sd) near esophoria was 0.4 ± 0.03 prism diopters. Significant near exophoria (with > 6 Prism diopters) was seen in 255 (49%) children.   Sd : standard deviation.

Discussion
This study is hospital based survey of children presenting with symptom of asthenopia. The hospital based prevalence in children (5-18 years) attending Pediatric and Ophthalmology Outpatient Department was 2.1%. This is markedly less than the asthenopia prevalence in population based survey in school children; these studies have shown prevalence of 12.4-57%. (14,17,19,20) This difference is can due to admission bias. Furthermore, the health seeking behavior in may be lacking.
In our study the proportion of male with asthenopia was higher as compared to girls. Similar results were seen by study by Hashemi H et al.(17) Ma L et al (21) showed a higher prevalence in females; while, Han et al. (19) showed no difference between the genders. This could be due to preference given to male child in our society; no scientific hypothesis could be made based upon gender. Age was as important determinant in asthenopia. The proportion of children with asthenopia increased with increase in age. Similar finding were observed in other studies. In 6 year old the prevalence of eye strain was found to be 15