The clinical picture of vernal kerato-conjunctivitis in Uganda
Vernal keratoconjunctivitis (VKC) is a recurrent, bilateral, interstitial inflammation of the conjunctiva, resolving spontaneously after a course of several years and characterised by giant papillae (with a cobblestone appearance) on the tarsal conjunctiva, a discrete or confluent gelatinous hypertrophy of the limbal conjunctiva, and a distinct type of keratitis. It is associated with intense itching, redness or brownness, lacrimation, photophobia and a mucinous, ropy discharge containing eosonophils.
VKC is a type 1 hypersensitivity reaction but with additional immune mechanisms involved in its pathogenesis.
VKC has a global distribution with a widely varying incidence. It is less common in northern Europe and North America, and more common in the African continent, the Mediterranean countries, in Central and South America, and the Indian subcontinent. 1, 2
All patients in this study were indigenous Africans, and all had been exposed to similar environmental conditions.
The high prevalence of VKC in Uganda, and the lack of data on the pattern and typical clinical picture of this medical condition provided the impetus for this study.
Subjects and methods
This study was carried out in two places, at the eye clinic, Department of Ophthalmology, Mulago National Hospital, and at the Medicare Clinic, a private eye consulting clinic in the capital city, Kampala, over a period of seven years, 1989 to 1996. A total of 420 patients with VKC were diagnosed on the grounds of their history, the presence of characteristic symptoms and on the basis of their clinical features. Clinical signs varied from mild to severe.
The history of each patient was taken including a record of age, sex, place of residence, change of place of residence, age at onset of the disease, seasonal variations, associated allergic or atopic illnesses, family history of VKC or associated allergic or atopic conditions.
Each patient was thoroughly examined with a slit-lamp or a binocular 3x loupe. Refraction with determination of visual acuity, retinoscopy, and assessment of the cornea with the placido disk to determine the presence of keratoconus were carried out. Patients who had any other keratoconjunctival disease were excluded from the study. All male patients underwent a full systematic examination.
Patients were reviewed once a month, and the period of follow-up ranged from a minimum of three months to a maximum of six years.
Each patient received treatment to relieve symptoms, hydrocortisone eye drops or prednisone eye drops, whichever was available at the time. If both were available, one or the other was given, picked at random by the clinic dispensing nurse.
Of the 420 patients, 231 (55%) were males and 189 (54%) were female.
Table 1 displays the age and sex distribution at the onset of VKC; the highest incidence of VKC occurred in the age group 5-9 years, and the lowest 20 years and above.
Table 1. Age and sex distribution of patients
|Age group in years||Sex Male (%)||Sex Female (%)||Total (%)|
|0-4||38 (9)||29 (7)||67 (16)|
|5-9||88 (21)||64 (15)||152 (36)|
|10-14||59 (14)||59 (14)||118 (28)|
|15-19||15 (3)||32 (8)||47 (11)|
|20 & above||9 (2)||28 (7)||37 (9)|
Corneal complications occurred in 231 (55%) patients; 196 had minor complications and 35 major complications or associations. The minor complications usually consisted of superficial punctate kerato-pathy, or other epithelial disturbance. Major complications or associations consisted of superior pannus and 15 with huge plaque formation which had already compromised patients’ visual acuity.
Patients with VKC often give a history of allergy or of atopic diseases such as allergic rhinitis, asthma, or hay fever but in my study, co-existing allergic conditions could be detected in only 47 (11%) patients. Of the 47 patients, 37 gave a history of asthma, rhinitis or both. The remaining 10 had atopic dermatitis.
All the three sub-types of VKC, namely limbal, mixed, and palpebral were seen. The most dominant sub-type is limbal, which constituted 75% of all patients. This was followed by the mixed type which was 18% of the total. Palpebral sub-type VKC was diagnosed in only 7% of the patients.
No patient presented with either hypogonadism or hypoadrenalism (see below).
I found no disproportionate high prevalence of the disease in male patients. Some previous workers have found a high prevalence of the disease in male patients.1,2,4
Some experimental work has shown that VKC is associated with hypogonadism and hypoadrenalism in males. Clinical evidence for this is based on findings in a Japanese population.6 However, my own findings in this study do not support the stated association.
Since 80 of my patients were under 15 years of age, this disease in Uganda is one of young persons, resolution mostly occurring at puberty.
Over 70% of all patients noted significant seasonal variations of their symptoms; more than 85% reported accentuation of symptoms during the hotter, drier months. Seasonal variability was marked in all the three sub-types, but was most marked in the limbal sub-type.
Limbal or mixed VKC had proportionately more corneal complications than the palpebral type. This finding agrees with those of Easty and others working in Europe and the Middle East. 7,8The high incidence of corneal involvement in limbal VKC is most likely due to poor limbal nutrition, affecting the nutrition of the avascular cornea. Some of my patients had keratoconus; other studies have reported even higher incidences.9
The often described typical appearance of changes on the tarsal conjunctiva intarsal VKC, that of cobblestone formation, was hardly seen. Only one patient out of the 29 with palpebral VKC presented with a mild form of cobblestone formation. Instead, there was a red to pink uniform colour, completely concealing all tarsal conjunctival vessels.
There is a well established association of atopic disease with VKC. Several authors who have investigated the exact nature of this relationship have come to varying conclusions.3,10 A low incidence of atopic disease in VKC in Uganda has been recorded. Relatively low incidences of atopic diseases in VKC have been recorded in other parts of the world.5,8There are no previous studies in either Uganda or other East African countries to make comparisons.
1 Khan M D, Kundi N, Saed N, Gulab A, Nazeer A F. A study of 530 cases of vernal conjunctivitis from the North West Frontier Province of Pakistan. Pakistan J Ophthalmol 1986; 2: 111-114.
2 Dahan E, Appel R. Vernal keratoconjunctivitis in the black child, and its response to therapy. Br J Ophthalmol 1983; 67: 688-692.
3 Tuft S J, Kemeny S M, Dart J K G, Buckley R J. Clinical features of atopic keratoconjunctivitis. Ophthalmology 1991; 98: 150-158.
4 Cameron J A, Al-Rajhi A A, Badr I A. Corneal ectasia in vernal keratoconjunctivitis. Ophthalmology 1989; 96: 1615-1623.
5 Aoki H. Relations of eye disease with thymus and endocrine glands especially with regard to experimental allergic conjunctivitis. Acta Soc Ophthalmol Jap 1968; 72: 1949-1965.
6 Easty D L, Birkinshaw M, Merrett T. Immunological investigations in vernal eye disease. Trans Ophthalmol Soc UK 1980; 100: 76-82.
7 Emarah M H. Vernal keratoconjunctivitis, diagnosis and management. Bull Ophthalmol Soc Egypt 1985; 78: 5-10.
8 Khan M D, Kundi N, Saeed N, Gulab A, Nazaar AF. Incidence of keratoconus in spring catarrh. Br J Ophthalmol 1988; 72: 41-43.
9 Tuft S J, Dart J K G, Kemeny M. Limbal vernal keratoconjunctivitis: clinical characteristics and immunoglobin E expression compared with palpebral vernal conjunctivitis. Eye 1989; 3: 420-427.