Therapeutic responses in vernal keratoconjunctivitis

Abstract

This was a single-blind placebo controlled study conducted at the Muhimbili Medical Centre between March 1989 and May 1990. It involved 60 patients with vernal keratoconjunctivitis, an ocular allergic inflammatory condition of world-wide distribution, involving mainly the conjunctiva and the cornea. The objective of the study was to find out the most efficacious therapeutic method in alleviating the signs and symptoms of the disease in our environment since different authori ties from different parts of the wold have claimed success using different therapeutic methods. The patients were randomly selected into four (4) groups, each subjected to a different therapeutic method. The therapy groups were: (i) placebo (ii) cryotherapy (iii) oral aspirin and (vi) steroid-antibiotic. The intensity of signs and symptoms were graded using a prepared score table. The higher the score, the more intense the disease was. After initial assessment, the patients were subjected to their respective therapies and signs and symptoms assessed and graded first weekly then twice weekly. The mean follow up period was 4 weeks. The odds-ratio method was used to assess the effectivity of the drugs with respect to placebo. Cryotherapy was found to be the most effective therapeutic method in alleviating signs and symptoms of the disease compared to other drugs used. A recommendation is made that patients with intractable vernal keratoconjunctivitis should be subjected to cryotherapy for relief of signs and symptoms. iii ...

---- ---- DECLARATION I hereby declare that this dissertation is my own original work and has not been submitted for a degree or diploma in any other university.

Signature DR. W.H. KIMWERI

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APPROVED:~ ~A-rv; (5.,_ Signatur~ • PROF. A.T. MTANDA (SUPERVISOR)

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Signature

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DR. N. KINABO (SUPERVISOR AND HEAD, DEPARTMENT OF OPHTHALMOLOGY) iv

--- - --- COPYRIGHT This dissertation shall not be copied or circulated in any form without the consent of the author or the University of Dar es Salaam on behalf. v

---- -- ACKNOWLEDGEMENT First and foremost, I wish to express my appreciation to all members of the academic staff in the Department of Ophthalmology, who, in one way or another contributed positively towards the accomplishment of this work. I am especially grateful to Professor A. T. Mtanda for constantly reading the manuscript, making the necessary corrections and for providing some literature reviews which were not available, locally. I am also grateful to Dr. N. Kinabo, Head of the Department of Ophthalmology, for his constant encouragement and for making the necessary arrangements which enabled the clinical trials to be carried out smoothly. I appreciate very much the assistance given by my former colleague Dr. (Mrs) M. Mafwiri in performing cryosurgery in some of the patients in the study. I would like to thank the following members of the nursing staff; Mr. J. Albert, Senior Ophthalmic Nursing Officer and his team in the Outpatient Clinic for helping in patient selection, random sampling and in providing medication and instructions for use to the patients; and Mrs. F. Kajanga, sister in charge of Theatre I and her team for their full cooperation shown during cryosurgery. Mrs. Msisi deserves special mention for her tireless effort shown during the typing of the initial manuscript. I wish to give special credit to my (younger) brother Mr. H.T. Kimweri and his colleagues in the department of Chemical and :vi•

Process Engineering, UDSM especially Mr. M. Osman for selflessly participating in the word processing of the manuscript albeit at short notice, and completing it in record time.

Lastly, but not least, I would like to express my special thanks to all my brothers and sisters for their moral and material support given throughout.

W.H. KIMWERI

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ABSTRACT DECLARATION COPYRIGHT ACKNOWLEDGEMENT INTRODUCTION

CONTENTS

iii iv v vi 1

II REVIEW OF LITERATURE (A) The Conjunctiva: (i)

Anatomical Considerations Gross Anatomy Microscopic Anatomy Blood Supply Lymphatic Drainage.

2 2 2 4 6 7

(ii) Pathological Changes in Inflammations 7 Acute Inflammations 7 Chronic Inflammations. 9 (iii) Hypersensitivity Reactions of the conjunctiva 11 Type I Hypersensitivity reactions. 11 Type II Hypersensitivity reactions. 12 Type III Hypersensitivity reactions. 12 Type IV Hypersensitivity reactions. 12

(B) Vernal Keratoconjunctivitis (i) Introduction viii

13 13

(ii) Pathogenesis and Pathology (iii) Treatment . Medical Therapy . Surgical Therapy III SPECIFIC OBJECTIVES IV MATERIALS AND METHODS V RESULTS VI DISCUSSION VII SUMMARY VIII REFERENCES ix

16 22 22 26 2 9 30 38 45 52 53

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1 INTRODUCTION Vernal Keratoconjunctivitis is an ocular condition with symptoms of itching, tearing photophobia and a stringy mucoid discharge from the eyes. It is associated with inflammation of both the bulbar and palpebral conjunctiva and sometimes corneal manifestations like corneal ulcers and keratoconus. Though the dangers of visual loss are minimal in this condition, the persistent itching and tearing is a source of great discomfort to the victim of the disease, so much so that very often medical advice is sought. There is no single specific treatment so far for this condition, though various authors have reported success in abolition of the sYmptoms with steroids (Neumann, 1958; Dahan et al., 1983), sodium cromoglycate (Easty et al., 1972; Forster, 1988) and cryotherapy (Amoils, 1975; Mtanda and Sangawe, 1983). Aspirin has once been tried in this condition with success (Abelson et al., 1983). There is a need to establish the efficacy of various reported therapies in this condition, in order to come out with the best alternative in our environment. This is possible in a placebo controlled, blind study comparing the various methods simultaneously. The resulting evidence may help us in managing the scores of patients with this condition with the best available medical or surgical alternative.

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2 REVIEW OF LITERATURE THE CONJUNCTIVA 1. ANATOMICAL CONSIDERATIONS: A. Gross anatomy: The conjunctiva is a thin, transparent mucous membrane that covers the posterior surface of the lids, and the anterior surface of the sclera, on the eyeball. It is continuous with the skin at the lid margins (mucocutaneous junction) and with corneal epithelium at the limbus. For the purposes of description, it is divided into three portions; the bulbar portion, palpebral portion and the fornix (Wolf E., 1968). I) The bulbar conjunctiva: This is a thin and transparent membrane, covering the anterior portion of the sclera, through which it clearly shows. It is loosely bound by loose areolar tissue to the underlying Tenons capsule and the sclera until about 3 mm from the limbus where it is more closely bound to them. At this point, the conjunctiva is slightly raised by a small ridge. This is known as the limbal conjunctiva, and the raised edge becomes more apparent in vernal conjunctivitis and other inflammatory conditions. At the limbus, the conjunctiva, Tenons capsule and sclera are all fused into a dense tissue. The bulbar conjunctiva is in continuity with the corneal epithelium and often diseases involving the conjunctiva may spread to involve the cornea and vice versa (Morehead R.P., 1965).

3 II) The Palpebral conjunctiva: This may be subdivided into the marginal zone, tarsal zone and orbital zone. The marginal zone: This is a 2 mm transition zone between the skin of the eyelids and the conjunctiva. It communicates with the nasal cavity through the lacrimal puncta which