Abnormal Visual Acuity Screening among Secondary Pupils in Owerri Urban

ABSTRACT 

A cross sectional descriptive study of visual acuity if post-primary school children in one urban and one rural communities in Owerri were undertaken. A total of 318 children were randomly selected using a multistage sampling procedure. Out of this number, 170 were males while 208 were females representing 45% and 33% respectively of the study group. The result of the study shows that about 21.4% post-primary school pupils have various degrees of subnormal visual acuity. Two thirds of these (14% of the total) have mild defects. There is a significant sex variation in prevalence, the female being more affected than the male (14%; 74%). There appears to be a relationship to height, tall pupils having a higher prevalence than short ones. Similarly, pupils who spend more time in close works has a higher prevalence that those who do not (14.7% and 100%) of those who read between 1 hour to 2 hours and 4 hours to 5 hours respectively. There is a significant hereditary influence on the incidence of subnormal vision (7.4% and 26.2% of those with negative and positive family history respectively). Eye defect is statistically dependent on family history P = 0.05. Finally the population studied presented no data on the age at which myopia commences, but earlier investigations have shown that only a minority are myopic before school age (6 years). After this age, the frequency of myopia increases from year to year.

TABLE OF CONTENT

Title page : : : : : : : : : : i

Declaration : : : : : : : : : : ii

Attestation : : : : : : : : : : iii

Dedication : : : : : : : : : : iv

Acknowledgement : : : : : : : : : v

Content : : : : : : : : : : : vi

List of Tables : : : : : : : : : : viii

List of Figures :: : : : : : : : : ix

Abstract : : : : : : : : : : : x

CHAPTER ONE – INTRODUCTION

1.1 Overview :: : : : : : : : : 1

1.2 Aims and objectives : : : : : : : 3

CHAPTER TWO: LITERATURE REVIEW

2.1 What is visual acuity? : : : : : : : 7

2.2 The structure of the eye and visual pathway : : : 8

2.3 The visual pathway : : : : : : : : 11

2.4 Refractive errors of the eye and amblyopia : : : 12

2.5 Factors affecting visual acuity : : : : : : 16

2.6 Previous investigations on the etiology of myopia : : 19

2.7 Signs and symptoms of eye problems : : : : 24

CHAPTER THREE: METHODOLOGY AND LIMITATIONS

3.1 The study population : : : : : : : 27

3.2 Nature and scope of study : : : : : : 27

3.3 Technique of data collection : : : : : : 28

3.4 Precautions : : : : : : : : : 31

3.5 Limitations of study : : : : : : : 32

CHAPTER FOUR: ANALYSIS AND RESULTS : : : 33

CHAPTER FIVE: DISCUSSION

5.1 General result : : : : : : : : 45

5.2 School variation : : : : : : : 48

5.3 Sex distribution : : : : : : : 49

5.4 Age distribution : : : : : : : 50

5.5 Hereditary influences : : : : : : 52

5.6 Myopia and social class/height : : : : : 54

5.7 Variation with duration of study time : : : : 57

5.8 Symptoms of visual impairment : : : : 59

CHAPTER SIX: CONCLUSION AND RECOMMENDATION

6.1 Conclusion : : : : : : : : 62

6.2 Recommendation : : : : : : : 64

6.3 Areas of further study : : : : : : : 68

References: : : : : : : : : : 70

Appendix : : : : : : : : : : 75