|Year : 1989 | Volume
| Issue : 4 | Page : 182-183
Tear film flow and stability in normal Indian subjects
SS Maudgil, AK Khurana, M Singh, IPS Parmar, BK Ahluwalia
34-9J-Medical Enclave, Rohtak, India
A K Khurana
34-9J-Medical Enclave, Rohtak
Source of Support: None, Conflict of Interest: None
Tear film flow and stability studies were carried out in healthy population by Schirmer's test-1 and tear film break-up-time (BUT) measurements, respectively. The mean BUT observed was 13.87 +/- 4.79 seconds; however, in 22 percent of cases the values of BUT were even less than the lowest values laid down by various workers, from the Western countries. Maximum dry spots were located in the temporal quadrant.
|How to cite this article:|
Maudgil S S, Khurana A K, Singh M, Parmar I, Ahluwalia B K. Tear film flow and stability in normal Indian subjects. Indian J Ophthalmol 1989;37:182-3
| Introduction|| |
A stable tear film with normal flow is essential for preserving a clear cornea. The determination of tear film stability by break-up- time (BUT) has been pro osed as a diagnostic aid in certain dry eye syndromes . IT has been observed that, so far, most of the work on the tear film flow and stability has been reported from Western countries normal values in Indian subjects. In view of this, the present study was designed to estimate BUT and Schirmer's test in our population and living conditions.
| Material and methods|| |
Tear film break-up-time measurement and Schirmer test-I were performed in 110 normal healthy subjects under similar environmental conditions. Thus, the study was carried out during the period November to February, when the weather conditions are more or less identical. Further, the tests were conducted in a room where the temperature and humidity remained relatively constant and without obvious ventilatory currents.
| TEAR FILM BREAK-UP-TIME|| |
A Flurescein strip moistened eith distilled water was applied to the inferior bulbar conjuctiva. The patient was asked to blink several times to distribute the fluorescein evenly and then to stare directly ahead without blinking; the eye lids were not held. The eye was then examined on a slitlamp with a cobalt blue filter. The time taken for the first dry spot to appear on the cornea was measured using a stop watch. This test was repeated 3 times in each eye, and the average was taken as BUT.
| SCHIRMER'S TEST|| |
Schirmer's tear test filter paper strips were inserted in the lateral part of the lower fornix without using any surface anasthesia. The patient was instructed to keep his eyes open and look up. At the end of 5 minutes the strips were removed and the dampness measured on a millimetre scale.
| Observations|| |
Out of 110 subjects 62 were males & 48 females. The mean values of the tear film break-up-time and Schirmer test observed were 13.8± 4.79 seconds with a range from 8 to 31 seconds and 27.90 ± 7.89mm/5min. with a range from 13 to 54mm/5min., respectively. Mean values of BUT in males and females of different age groups are shown in [Table - 1]. [Table - 2][Table - 3] depict the range of value of BUT and Schirmer's test, respectively. The quadrant wise distribution of dry spots is depicted in [Table - 4]. Maximum dry spots were located in the temporal quadrant (130) followed by nasal (95), inferior (68) and superior (37). [Figure - 1], the scattergraph shows partial negative correlation between BUT & Schirmer's test values, indicating thereby that these two parameters are independent of each other. Pearson's correlation co-efficient was calculated to be-0.265.
| Discussion|| |
In the previous studies on tear film flow and stability we have compared the results only in 25 healthy subjects with 25 patients each of trachoma grade-111  squamous blepharitis  herpes simplex keratitisl , chronic dacryocystitis  and acute & chronic conjuctivitis . To authenticate on the normal values of these parameters in healthy subjects of different ages and sexes, and also to compare the values with those reported from Western countries the study was further extended to make a total of 110 subjects. In the present study the mean value of BUT observed was 13.8 ± 4.79 seconds with a range from 8 to 31 seconds. In 22 percent of the healthy subjects the values of BUT were even less than the lower limit for normal BUT suggested by various workers from Western countries(1,6) similar low values of BUT have also been reported by Sukul et aI  and Tiwari et alt . Probably, these low values are due to the tropical climatic conditions in India as against the temperate climate of Western countries. Another factor responsible for lower BUT in our population may be due to working in the fields. Thereby causes greater exposure to the hot and arid climate which increase the tear evaporation rate thus rendering the tear film unstable. Lamba et al (9) in their study-evaluation of pre-corneal tear film in leprosy, have taken cut off values of BUT as 15 seconds. Our observations militate against their view we suggest a cut off point of 10 seconds for BUT in the Indian population. Chopra et al  have reported mean values of BUT innormal Indian population, even less than 10 seconds (males 8.9 seconds and females 6.98 seconds). However, most of the Indian worker ,, consider BUT values less than 10 seconds as abnormal. Norn  reported that females tend to have shorter BUT, however, Lemp et al  and shapire & Marin  could find no statistically significant difference in the BUT values of the two sexes. The mean values of BUT in our study though, were identical in men and women; yet females in the age group of 11-40 years had slightly shorter BUT whereas those in the age group of 41-70 years had slightly large BUT than the males [Table - 1]. Whether hormonal differences between these two major age group have a role to play inthis disparity, is a tempting speculation. Further, we could find no statistically significant difference in the values of BUT in the various age groups. Lemp and Hamil  also did not observe any correlation between BUT and age; Brown  remarked that BUT tends to be shorter in the elderly. As regards location, the maximum dry spots were located in temporal quadrant followed by the nasal, inferior and superior quadrant [Table - 4]. Similar observations have been made by Ehlers  and Rengstroff . The preponderance of dry spots in the temporal area in comparison to the other quadrants may be due to the facts that the former is least protected against air currents .
The mean value of Schimer test-I observed was 27.90 + 7.89mm/5min. The mean levels noted in females (33, 27+ 10.5mm/5min) were higher than in the males~25.21 + 5.11 mm/5min. p) Henderson and Prough  also reported higher values in females. Parmer  suggested that these higher values in females might be due to hormonal influences. However, with the increase in values of Schirmer's test, we could find no corresponding increase or fall in BUT values [Figure - 1] depicting thereby that Schirmer's test and break-up-time are independent of each other. Similar observations were made by Lemp et al  and Kame et al . Shapiro and Merin  also failed to find any correlation between the Schirmer test and But; and concluded that BUT cannot be used as a test to evaluate tear volume of flow as also suggested by Norn.
| References|| |
Lemp, M.A. & Hamil, JR.: Arch. Ophthalmol. 89:103-105. 1973.
Moudgil, SS: Singh, M.: Parmar, IPS & Khurana A.K. Acta Ophthalmol (Copenh) 64:295-297.1986
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[Figure - 1]
[Table - 1], [Table - 2], [Table - 3], [Table - 4]
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