Year : 1991 | Volume
: 39 | Issue : 2 | Page : 55--58
Hospital epidemiology of dry eye
AK Khurana, R Choudhary, BK Ahluwalia, S Gupta
Department of Ophthalmology II, Medical College, Rohtak-124 001, Haryana, India
A K Khurana
34/9J-Medical Enclave, Rohtak - 124 001. Haryana
One hundred consecutive cases of dry eye were studied to comment upon its epidemiological aspects. The incidence of dry eye amongst ophthalmic outpatients was 0.46% with a male:female ratio of 1:1.22. Fifty seven percent of the patients were above 50 years of age. The incidence was higher amongst outdoor workers and people from rural areas with poor socioeconomic status. The influence of hot and dry climate and nutritional status on dry eye incidence is discussed.
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Khurana A K, Choudhary R, Ahluwalia B K, Gupta S. Hospital epidemiology of dry eye.Indian J Ophthalmol 1991;39:55-58
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Khurana A K, Choudhary R, Ahluwalia B K, Gupta S. Hospital epidemiology of dry eye. Indian J Ophthalmol [serial online] 1991 [cited 2021 Apr 21 ];39:55-58
Available from: https://www.ijo.in/text.asp?1991/39/2/55/24469
Dry eye is described as a state of abnormal tear film that can be caused by a number of conditions which alter its composition and affect stability. Epidemiological studies as regards incidence, etiology and influence of other factors like habitat, environment, socioeconomic status, climate, nutrition and educational status on aetiopathogenesis of dry eye are lacking in the available literature; the Indian scene being more unclear. Further, as the epidemiological factors are bound to differ from region to region, the present study was taken to comment on such factors in relation to dry eye in this region.
MATERIAL AND METHODS
One hundred consecutive patients of dry eye diagnosed clinically and confirmed by tear film profile were included in this study. In each case a detailed personal history as regards habitat, occupational status, dietary habits, educational status, smoking habits, socioeconomic status and accompanying factors like exposure to sun, dust, etc. was meticulously recorded along with the history of the case. The results were computed and analysed to comment on the epidemological aspect of dry eye.
21683 patients reported on clinic days in the department of ophthalmology for various ocular affections during the study period i.e. between February 1, 1989 and March 10, 1990. 197 patients were picked up on the basis of symptoms, and 141 were found to have clinical signs suggestive of dry eye syndrome. One hundred consecutive patients of dry eye were diagnosed from these suspected patients on the basis of tear function tests. Thus, the incidence of dry eye amongst the hospital population was 0.46 %.
Age and Sex Distribution:
Out of a total of 100 patients of dry eye, 55 were females and 45 were males, with a female:male ratio of 1.22:1. The youngest patient was 5 years old while the oldest was 78. The mean age was 49.19 years. The maximum number of patients (26%) were in the age group 60-69 years followed by those in the 50-59 years age group (21%) [Table 1].
Seventy four percent of the patients had a rural base while 26% came from urban areas.
Fifty nine percent of the patients reported during summer while 41 % presented during the winter season. The maximum number of patients attending the department in a single month was 2,489, in April 1989, while the highest number of patients of dry eye reporting in a single month was 11, in the month of June, 1989.
Thirty two percent patients (22 males and 10 females) were farmers, while 28% (10 males and 18 females) were labourers by occupation. Others included businessmen/executives 4%, office workers 5%, housewives 19% and students 12% [Table 2].
Sixty eight percent of the patients had a monthly income less than Rupees 750 and 42% had less than Rupees 500. Only 10% of the patients earned over Rupees 1000 per month.
72% of the patients suffering from dry eye were vegetarian while 28% were non-vegetarian. 88% of the patients used to take 2 principal meals while 9% took it thrice. Milk was the commonest source of vitamin A consumed by 31 % of the patients. The intake of green leafy vegetables and fruits was noted in 18% and 6% patients, respectively [Table 3] depicts the dietary habits of dry eye patients.
About half i.e. 49% of patients of dry eye (22 males and 27 females) were illiterate while 21 % were matriculates or above.
Forty percent (75% males) of the patients were smokers, of which 14 (35%) used to smoke cigarettes, 17(42.5%) bidis and 9 (22.5%) hukka. Of smokers, 31 (77.5%) patients hailed from the rural area.
Seventy eight percent of the patients were noted to be exposed to the sun and/or dust, more than six hours a day. [Table 4] shows other associated factors in dry eye patients.
The incidence of dry eye amongst ophthalmic outpatients in the present study was 0.46%. In the available literature we could not find such a report describing the hospital prevalence of dry eye. However, dry eye syndrome was found to constitute about 4% of all corneal affections in a report from North India . There was a high index of clinical suspicion in diagnosis, as out of 141 suspected cases (on basis of clinical profile), 100 were confirmed as dry eye patients by tear film profile.
The mean age of dry eye patients was 49.19± 19.79 years, and 57% of the patients were above 50 years of age. This is, because most of-the diseases viz. trachoma, Sjogren's syndrome and idiopathic keratoconjunctivitis sicca (KCS), responsible for dry eye, are common in this age. The decreased quantity of tears as indicated by decreasing Schirmer values with advancing age  may also explain the age incidence of dry eye in some cases. In one study, non-vitamin A deficient xerophthalmia was reported to be common below 12 years of age . Dry eye was more common in females than males in the present study, the ratio being 1.22:1. Female preponderance is well documented in Sjogren's syndrome .
High temperature and low humidity have been noted to decrease Schirmer values . An abnormality of tear film has been thought to be initiated in an arid climate with low humidity and dry winds  which may predispose to pterygium . These findings prompted us to study the effect of climatic factors on dry eye. 74% of dry eye patients belonged to rural areas while 26% had an urban base. 60% of patients had an occupation that kept them outdoors most of the time. Further. 78% of the patients were noted to be exposed to sun and/or dust more than 6 hours a day, 6% to the heat of furnaces and 2%. were driving a two wheeler more than 4 hours a day without air/dust protective devices. These observations and the fact that more number of patients (59%) reported in summer as compared to 41% in winter, indicate some association of climate with occurrence of dry eye.
The rural people and those with outdoor occupation are more exposed to extraneous influences. It may be possiblethat the heat, low humidity, high temperature, direct hot air currents and dust in tropical climatic conditions in our country have a drying effect on the preocular tear film and the ocular surface. These conditions, alone or in combination may initiate or aggravate a dry eye due to trachoma, Stevens Johnson syndrome, idiopathic KCS, and possibly chronic blepharitis and blepharoconunctivitis. Meibomian keratoconjunctivitis causing dry eye has been seen to be associated with staphylococcal blepharitis in warm and dry climates . These factors may render the tear film unstable by direct mechanical damage or by increasing evaporation, has been thought to be important in the aetiopathogenesis of certain dry eye syndromes like KCS, Stevens-Johnson syndrome, ocular pemphigoid and meibomitis. Kanski  states that evaporation of tears is dependant upon temperature and humidity at the air-tear interface, air flow over the surface of eye, surface area of the inter palpebral fissure and integrity of the lipid layer of the precorneal film. Irregularities in the corneal surface are stated to be caused at high attitudes and in desert areas due to increased evaporation, low humidity and winds leading to poor wetting. Further, the suggestion that for dry eye patients the room temperature and humidity should be decreased and increased, respectively, and protective devices should be worn by the patient to combat the effect of winds in an outdoor setting , supports the observations made in the present study. Furthermore, the hot and dry atmosphere has been believed to aggravate various symptoms of dry eye like gritty. sandy and foreign body sensations , which might compel the patient to seek advice and may explain a higher number of patients reporting during summer in this study. Apart from the influence of these outdoor environmental factors, certain chemicals and surface active compounds as a part of indoor climate of non-industrial buildings have been cited to cause ocular irritation and dry eye syndrome being called office eye syndrome .40 (40%) of the patients were smokers. The relationship between smoking and dry was not studied in the past, but exposure to tobacco smoke has been reported to increase symptoms of dry eye. Similarly, cigarette smoke has been noted to decrease the tear film break up time (BUT) substantially (30-40%).
Most of the patients in the present study had poor socioeconomic status, 90% having monthly income of less than 1000 rupees(42% less than 500). About half (49%) of the dry eye patients were illiterate. Probably, because of these two reasons only 24% used to take green leafy vegetables and/or fruits. Milk was the commonest source of vitamin A, consumed by 31% of the patients. Xerophthalmia has been recognised to be caused by a dietary deficiency of vitamin A .The role of vitamin A in the aetiopathogenesis of other dry eye diseases is less understood. Squamous metaplasia of the ocular surface is a common manifestation of various dry disorders and has been speculated to be due to relative local deficiency of vitamin A because of loss of vascularization owing to scar formation in the chronic cicatricial stage and the intense inflammation in the acute inflammatory stage. A deficiency of this vitamin can convert secretory epithelium to stratified squamous epithelium (squamous metaplasia) and its excess amounts, as following topical application of tretinoin , can convert a stratified squamous epithelium to secretory epithelium (mucous metaplasia) . Since vitamin A is an essential factor for epithelial growth and differentiation , a dietary lack or local deficiency of this vitamin accounting for squamous metaplastic changes in dry eye disease is a compelling speculation.
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