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Screening of Refractive Errors Models

Paper Type: Free Essay Subject: Health
Wordcount: 2512 words Published: 13th Oct 2017

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Student Research Communiqué

TITLE: – Comparison of two models for screening of Refractive errors in school going children of rural area in Vadodara, Gujarat


Introduction– Globally there is 18.2% of blindness due to the uncorrected refractory errors. Most of the children with uncorrected refractive error are asymptomatic and hence screening helps in early detection and timely interventions.

Aim- To compare validity and reliability of refractory error screening by trained school teacher with trained medical students.

Methods- Training was given to the teacher of the standard 5-8 regarding how to diagnose the refractory error among School children by using snellan’s chart. Result reports were collected from teachers. After two week investigator team visited the school and screen for refractory error in the same school children by using snellan’s chart. Results of these screening methods were analyzed and compared.

Result- Kappa statistics: – 0.4482 indicate the reliability and Sensitivity = 31.25%, Specificity = 96.40% indicate the validity of screening method 1 (screening by school teacher ) compare to method 2 (screening by medical students)

Conclusion- screening by school teacher is not useful model for diagnoses of refractory error among school going children.


In the visual impairment both Blindness & Low vision included. Worldwide 285 million people are suffering from visual impairment, among these 39 million are blind and 246 million have low vision. Globally, uncorrected refractive errors are the main cause of visual impairment. 43% of visual impairment is due to refractory errors. 80% of all visual impairment can be avoided or cured.1

In India refractory error is the second most leading cause for all age group but it is the first among child age group for visual impairmnet.2

Refractive Error is defined as a state of refraction, when the parallel rays of light coming from infinity are focused either in front of or behind the sensitive layer of retina, in one or both the meridians.3

It is also known as Ametropia. The Ametropia includes Myopia, Hypermetropia and astigmatism. Myopia or Short-sightedness in which parallel rays of light coming from infinity are focused in front of the retina when accommodation is at rest. Hypermetropia or Long-sightedness is the state of the eye wherein parallel rays of light coming from infinity are focused behind the retina with accommodation being at rest so the posterior focal point is behind the retina which therefore receives a blurred image.3

The children aged 5 – 15 are school going students. Refractive error in such age group can harm their learning capicity. So Early diagnosis in schools for refractive error can be useful to stop the increasing number of such disability and qualitative education can be got by the school going students.

A simple Eye test and glasses can restore sight to most of affected people. As for WHO, correction of Refractive error is a component of currant global initiative to reduce avoidable or treatable blindness, in Vision 2020 which is considered a current top priority and challenge for all the nations.4

Strategies to address eye health of children in India have focused on school eye health programme. School eye health screening is also part of the national blindness control programme.5 If, we trained the school teachers for identification of refractory errors among school children using vision chart than it will serve as alternative of tradition eye screening programme. Routinely eye screening was done annually but if, school teacher is trained in such procedure they can screen every student systematically using appropriate time and also do such screening twice in a year. So here this study was conducted to find alternative of refractory error screening by health profession. By this way the burden over existing health care system will reduce. Here we compare two screening model and check the validity and reliability of new model (Refractory eye screening by school teacher).


  • Study Population:-School going children (Standard 5-8)
  • Design of the study:- Screening study
  • Study Area:- Rural area of Vadodara taluka
  • Sampling:- Random sampling mthods
  • Sample size:- 150
  • Inclusion criteria:-
  1. School going children of standard 5th to 8th
  • Exclusion criteria:-
  1. Study participant suffering from refractory error and already diagnosed for refractory error.
  2. Participant does not want to participate in study.
  • Methodology:-

Before Study started, we obtained the permission from the ethical committee of Sumandeep Vidyapeeth. Then we obtained the list of rural schools in Vadodara taluka from DEO office, Vadodara. We selected randomly one school from the list by lottery method. Selected school was Government school, Amodar. After selecting the school, we also obtained the permission from school principal to conduct this study in their school. We discussed with teacher regarding the various aspects of study. All teachers agreed to volunteer participate in the study. We gave training to the teacher of the standard 5-8 regarding “how to diagnose the refractory error in School children by using snellan’s chart”.

Training of Teacher-

Those school teachers, who ready to voluntarily participate in this project, were trained for identification of refractory error by using snellan’s chart. First we gave some basic information about refractory error in understandable local language (Guajarati), then we demonstrated them how to diagnose refractory error by using snellan’s chart. Every teacher had to perform this procedure in front of us to insure that they understand the whole procedure. Those who had doubts and difficulties was discussed, and corrected so every teacher uses this procedure with same standard.

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We included all the students from class 5th to 8th of selected school in to study. Total 150 students participate volunteer. After obtaining informed consent from students and their parents, visual acuity was measured and recorded by teachers. On another convenient day same children were examined by Investigators (medical students) in absence of teacher using the identical protocol and same vision charts. To avoid bias we masked the teachers’ results (first screening result) during second screening .

Statistical analysis

Data collected in individual forms for every student were compiled in Microsoft Excel sheet. Validity and reliability of model 1 “refractory error screening by school teacher” is compared with model 2 “refractory error screening by medical students”. Sensitivity and specificity, positive predictive value and negative predictive value indicate validity and Kappa statistics indicate reliability.


Figure 1- Sex and Age wise distribution of study participant

Figure 1 shows the sex and Standard (Class) wise distribution of the study participant.

Table 1- Distribution according to Diagnosis by School teacher and medical students


Diagnosed By Medical student




Diagnosed By school Teacher













  1. Kappa statistics: – 0.4482
  2. Sensitivity = 31.25%
  3. Specificity = 96.40%
  4. PPV = 50.00%
  5. NPV=92.41%

Table 1 shows that screening result of two models, kappa statistics is an indicators of reliability. In our study kappa statistics is found 0.4482, it indicates poor reliability it indicate only 44.82% of result has similar results between two screening methods. In our study, validity is determined by sensitivity and specificity. Sensitivity is very low 31.25% while specificity is 96.40%. it shows that Screening model 1 (screening by school teacher) identify only 31.25 % of students suffering from refractory error and missed 68.75% of students suffering from refractory.


Study shows the diagnostic ability of trained school teacher in diagnosis of refractory errors as compared to diagnosis of refractory errors by medical students by using same vision chart.

A refractory error is the one of the common ocular morbidity among the school going children.6 School health programme is the only one opportunistic screening where refractory error can be diagnosed in Indian health system. Due to the lack of the health worker, every school student is not screened using standard methods.7 Here we tried to compare another model of refractory error screening (screening by school teacher). This is the cost effective model because training of teachers and vision chart is the only requirement for implementation of such health delivery model. If refractory errors is missed to identify than it will lead to considerable disability to the students so sensitivity must be high enough. But in our study the sensitivity is very poor (31.25%). In the study of Anand sudhan sensitivity was found very good and specificity was very low as opposite to our study result.8


In our study, we compare the Model 1 (Screening by Teacher) with Model 2 (Screening by Medical student). Screening by teacher has poor sensitivity and reliability compare to screening by medical student. So the model 1 (Refractory error sceening by scholl teacher) is not useful health delivery model because it is unable to identify the student with refractory error by required sensitivity.


We are thanks to the District education officer (Vadodara), Principal (Government school, Amodar) and teachers of Government school, Amodar, without their kind support this project is not possible.


1.http://www.who.int/mediacentre/factsheets/fs282/en/ dated on 09/03/2013

2. Park.K, Non Communicable disease, Textbook of preventive and Social medicine, 21th edition, Jabalpur (India), M/s Banarsidas Bhanot Publisher, 2011:335-379.

3. A K Khurna, Refractory Error, Comprehensive Ophthalmology, 5th edition, New age international publisher, 2012, 28-32

4.http://www.scielosp.org/scielo.php?pid=S004296862001000300013&script=sci_arttext dated on 04/09/2013

5. Limburg H, Kansara H. Result of school eye screening of 5.4 million children in India- a five year follows up study. Acta opthalmo scand: 1999; 77: 310-314

6. B.T.Prasanna Kamath, B.S.Guru Prasad, R.Deepthi, C.Muninrayana. Prevalence of ocular morbidity among school going children (6-15years) in rural area of Karnataka, South India. Int J Pharm Biomed Res: 2012, 3(4), 209-212.

7. GVS Murthy. Vision Testing for refractory errors in schools- “Screening Programmes in Schools” Community Eye Health: 13(33). 3-5

8. A sudhan, A pandey, suresh pandey, P shrivastav et al. Effectiveness of using teachers to screen eyes of school going children in Satna district of Madhya Pradesh, India: Indian J Opthal: 2009; 55: 455-458.


  • Colored texts are entirely copy pasted

Answer: – corrected

  • The author has mentioned medical professionals at one place and medical student at another place. There is a scope for ambiguaty. In this type of study where comparision is made between layman and medical man, it would be nice to mention 1st year, 2nd year or degree holder doctor. It will increase the importance of parameters of comparison.

Answer:- here we are not compare the laymen with the medical student. here we compare the teacher trained to diagnose refractory error with third year medical students ( already skilled to diagnose refractory error). Under national school health programme teacher has to screen the children for the refractory error. Here we check the validity of this method.

  • Materials and Methods section should be written in paragraph format

Answer: – corrected

  • The entire texts need a meticulous copy editing.

Answer: – corrected

  • Reference no. 4 is not opening

Answer :- It is not accessed now, but on it 04/09/2013 was accessible. The content may be removed by the website.

  • Overall comment:

Comparing the ability to perform a task which concern to medical expertise between a medical man and a layman need more justification. It shall be incorporated in the background and/or Introduction part of the manuscript. In other words, the author has failed to justify the “need of the study”.

Answer: – In the last paragraph of introduction it is already mentioned the need and purpose of the study added the some sentences

Final comments: 14-08-2014

I believe that the manuscripts send to the reviewers are already checked for pliagarism. Therefore I am not scrutinizing whether the copy pasted portion shown during 1st review are taken care or not.

I still believe that the research conducted is not worth publishing for the reason of deficiencies in

  1. Justifying the need of the study

b. Material and method section (it even does not mention the total no of participants, instead has mentioned all students belonging to stad 5-8).

C. Professional scientific writing.


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