Ocular Morbidity among Children of Government Schools of Kathmandu Valley : A Follow-up Study

Introduction: Ocular and vision defects are common among school going children. Vision disorders, especially refractive errors are the main disabilities of children and the leading cause of handicapping conditions of childhood. The present study was conducted to find out ocular morbidity among students of government schools of Kathmandu valley. Methods: In the descriptive and cross-sectional study, 2412 students, comprising of 1114 (46.2%) males and 1298 (53.8%) females were enrolled in to the study from the five government schools of Kathmandu valley from 2012 to 2013. Detailed eye examination included distance visual acuity testing, anterior and posterior segment examinations, retinoscopy and refraction, cover test, near point of convergence, amplitude of accommodation and color vision test. The Chi-square test was performed to analyze the association between ocular morbidity, age and sex. P value was considered significant at 0.05 for 95% confidence interval. Results: Majority of children were age group between 11 and 13 years (n= 783, 32.5%). A male to female ratio was 0.85. Presenting and best spectacle corrected visual acuity of 6/6 was present in 2257 (93.6%) and 2380 (98.7%) respectively. Total ocular morbidity was observed in 515 (21.4%) subjects. The most common types of ocular morbidity were refractive error in 241 (10%), conjunctivitis in 104 (4.3%) and convergence insufficiency in 82 (3.4%). Conclusions: Refractive error, conjunctivitis and convergence insufficiency represent the most common ocular morbidities among students of government schools. _______________________________________________________________________________________


INTRODUCTION
Vision-2020: The Right to Sight has recognized the childhood blindness a major priority owing to the large magnitude of childhood blindness and most cases of childhood blindnesses are avoidable. 1,2evalence of ocular morbidity and refractive error has been conducted among different groups of children in many parts of Nepal.Way back in 1981, Nepal Blindness Survey identified relatively few cases of the childhood blindness, and the finding mostly comprised of ocular infections, xerophthalmia and congential cataract. 3][7][8][9][10] A report of a comparative study on ocular morbidity among children of government and private schools of Kathmandu valley was presented in 2011 that reported refractive error and strabismus were the major ocular morbidities. 11art from regular eye examinations among school children, effective and repeated eye examination in school children are necessary in reviewing the progression and changes in pattern of ocular morbidity, managing vision related problems, and minimizing long term visual disability.The present study was conducted to find out the ocular morbidity among school children in government schools of Kathmandu valley.This program is an initiative to provide repeat eye examination, provide appropriate treatment and gather information on ocular morbidity where initial eye examinations were conducted in 2009. 11

METHODS
In a descriptive, community based, and cross-sectional study, five government schools in Kathmandu valley were selected for repeat eye examination from 2012 to 2013.All the children attending the schools visited were enrolled into the study.Very few children who were absent at the time of eye examination were left out.They were the students studying from grade one to grade ten.There were a total of 2412 students comprising of 1114 males (46.2%) and 1298 females (53.8%) underwent detailed eye examination.Ethical approval was obtained from the Institutional Review Committee of Nepal Medical College, Teaching Hospital prior to the commencement of the study.The purpose of the study was explained and an informed consent was received from the head of the schools and the parents of the students who were present at the time of eye examination.A team of ophthalmologists, optometrists, and ophthalmic assistants visited each school for the detailed ocular examinations.
Uncorrected, presenting and best spectacle corrected visual acuity (BSCVA) was measured in internally illuminated Snellen vision chart at 6 meters distance.Extraocular movement was performed in six cardinal gazes and cover test and prism cover test was performed using torch light and prism bar both at six metres distance and 40 cm distance.Near point of convergence and Amplitude of Accommodation were tested using the Royal Air Force (RAF) rule.Color vision was screened with the help of Isihara pseudoisochromatic plates, 38 plates edition.The child was diagnosed as having color vision defect if the child made mistakes in identifying numbers in six or more plates of the chart.
Static retinoscopy and subjective refraction were performed in all children to find out refractive errors.Cycloplegic refraction was carried with 0.5% cyclopentolate in all the cases of hypermetropia, strabismus, amblyopia, unstable end point of refraction, scissor reflex, anisometropia more than 0.50D, high refractive error, and subjects where vision couldn't be improved with normal refraction.A cyclopentolate 0.5% drop was instilled three times at an interval of 10 minutes and refraction was carried out after 45 minutes from the first instillation.This process was followed by subjective refraction after three days.
Anterior segment examination was carried out with Haag Streit Slit lamp and posterior segment examination was carried out with Haag Streit Slit lamp with 90D lens and direct ophthalmoscope in all children.All the findings were recorded in the preset proforma.
The diagnosis of myopia and hyperopia was made when the spherical equivalent was 0.50 dioptres, and for astigmatism, error equal to or greater than 0.75D was considered significant.The diagnosis of amblyopia was made if visual acuity was worse than 6/9 after meticulous refraction in the absence of any ocular pathology.The diagnosis of strabismic amblyopia was made if the reduced visual acuity was due to the strabismus.Similarly, the diagnosis of refractive amblyopia was made if there was anisometropia of 1.00 dioptre for hypermetropia and 4 dioptres for myopia.The students that required further evaluation and treatment were referred to the nearest hospital.
All the data were entered in the statistical package for social studies version 16.0.The Chi-Square test was performed to analyze differences in refractive error between males and females, and among different age groups.The P-value for confidence interval of 95% was considered significant at 0.05 for prevalence estimates.

RESULTS
A total of 2412 students comprising of 1114 males (46.2%) and females 1298 (53.8%) were examined between 5 to 16 years of age were examined with mean age of 12.6± 4.2 years (Table 1).Most of the children (n=783, 32.5%) belonged to the age group 11 to 13 years of age and to the females (n=1298, 53.8%).

DISCUSSION
The present study reports the pattern of ocular morbidity among students of government schools of Kathmandu.We have already presented ocular morbidity profile among students of private and government schools of Kathmandu. 11In present study, we have selected the same government schools where eye examination was carried out in 2009. 11e total ocular morbidity in the present study is 515 (21.4%).This finding is slightly higher than findings of our previous study that is 404 (18.7%) among students of government schools. 11The prevalence of ocular morbidity is more common in males than females (p=0.00;Odds 2.1; 95% CI 1.7-2.6).][8][9][10]12 They included the children of private schools, government schools, primary school, squatter settlements and street children.This variation in morbidity can also be caused by variation in age range, research settings, sample size and sampling design.
In the study, refractive error is the major cause of ocular morbidity in 241 (10%) students.4 This variation is also well explained by variable research settings, geographical variation, types of schools and age groups of the study population.However, the common entity that all the studies have shared, is the presence of myopia as a common refractive error except Sherpa et al, (2011) study which is conducted among primary school children. 9In our study, myopia accounts for 180 (74.7%) of total refractive errors.
The conjunctivitis among 104 cases (4.3%) and blepharitis among 82 cases (2.5%) also constitute a major threat to ocular health conditions in our study.These conditions can be easily tackled by instituting proper treatment and can be prevented by teaching how to maintain proper ocular hygiene.2,14 Lid related conditions and blepharitis are reported to range from 0.8% to 9.6%. 7,9,10,12These studies were conducted among school children 9,10,14 orphanages of Kathmandu, 8 street children 12 and children of squatter settlement 7 .Like in the previous studies, 7,10,11 convergence and accommodation are also commonly noted in our study among 82 (3.4%) and 65 (2.7%) students respectively.
Uncorrected, presenting and best spectacle corrected visual acuity (BSCVA) of 6/6 is present in 2230 (92.5%), 2257 (93.6%) and 2330 (98.7%) respectively.There is an agreement in finding of visual acuity in the literature. 14Prevalence of amblyopia and strabismus has been noted to be 31 (1.3%) and 41 (1.7%) in our study.The more common entities are aniso-strabismic amblyopia and exotropia.In the literature amblyopia and strabismus are reported in the range from 0.13% to 2.0% 5,7,9,11,14 and 0.6% to 3.2% [5][6][7]11 respectively. Altough amblyopia and strabismus represent a small proportion of ocular morbidity, the consequences of these conditions can't be neglected for their nature of permanent visual impairment if cure is not initiated on time.So an effective intervention has to be initiated timely to tackle such conditions.
In summary, we have compared a pattern of ocular morbidity among students between previous report of government schools 11 and the present report of the same government schools.Though refractive error has remained to be the stable and leading cause of ocular morbidity, ocular infections among 157 (6.8%) students, such as conjunctivitis and blepharitis are more commonly seen in present study than previous one among 45 (1.95%) students.Similarly strabismus is less prevalent among 41 (1.7%) students at present eye examination than previous one among 71 students (3.13%)where as amblyopia is seen more in present study among 31 students (1.3%) than previous one among three students (0.15%).Accommodative insufficiency is significantly noted in present study.However previous study, accommodative insufficiency was not reported rather mean amplitude of accommodation was only presented as 7.27 cm.The present study suggests that children have to be taught more about importance of maintaining hygiene and environmental sanitation to improve their hygiene behaviour.This issue can be tackled by introducing health programs at schools and periodic eye examination.
Limitation of the present study is lack of enumeration of school children to compare the real change in the ocular morbidity, though we conducted the eye program in the same government schools.Another limitation is in its generalization that the sample is being taken from only a few schools.

CONCLUSIONS
Children of government schools have significant ocular morbidity, especially refractive error, conjunctivitis and convergence insufficiency being the most common causes.The periodic eye examination is necessary to assess changes in pattern of ocular morbidity and plan interventions.

Figure 1. Distribution of refractive error in male and female students.
Two cases with cataract were traumatic in origin and associated with corneal opacity.Among 10 miscellaneous cases, diagnosis consisted of two cases proptosis, one case of juvenile glaucoma, two cases of nystagmus, two cases of retinal scars, one case of keratoconus and two cases of glaucoma suspects.