|Year : 2019 | Volume
| Issue : 3 | Page : 217-220
Correlation between pterygium and dry eye
Aruna Kumari R. Gupta, Yashvi Nathwani
Department of Ophthalmology, C. U. Shah Medical College and Hospital, Surendranagar, Gujarat, India
|Date of Web Publication||31-Dec-2019|
Dr. Aruna Kumari R. Gupta
Department of Ophthalmology, C. U. Shah Medical College and Hospital, Dhudrej Road, Surendranagar - 363 001, Gujarat
Source of Support: None, Conflict of Interest: None
Objective: The aim of this study is to evaluate the correlation between dry eye and pterygium. Materials and Methods: A total of 50 patients, aged between 26 and 70 years, were included in this study. Tear film breakup time (TF-BUT) and Schirmer's test (ST) results were compared in pterygium eye and contralateral normal eye of the same patient. TF-BUT and ST results were compared in pterygium eye and contralateral normal eye for different sizes. The paired t-test was used for the analysis. The Pearson correlation was used to assess the correlations of tear BUT and ST with pterygium size. Results: The mean horizontal size of pterygium ± standard deviation (SD) was 2.35 ± 0.54 mm. The mean ± SD of TF-BUT in pterygium eyes was 7.1 ± 2.34 s compared with 9.18 ± 3.21 s in contralateral normal eyes (P < 0.05). The mean ± SDs of ST results in pterygium eyes and the opposite normal eyes were 8.96 ± 2.66 and 10.94 ± 3.88 mm, respectively (P < 0.05). On analysis, the overall difference in the mean TF-BUT between the pterygium eyes, and the contralateral control eyes was significant (P < 0.01). The difference in the ST between the pterygium eyes and the contralateral eyes was not significant for size < 1 (P = 0.17) and 1-2 (P = 0.4) but was highly significant for size <2 mm (P < 0.001). Most patients with pterygium complained of mild-to-severe ocular discomfort. Ocular Surface Disease Index score was found to be 30.6. Conclusion: Results of the present study strongly suggest that pterygium induce abnormal ocular surface conditions, which lead to dysfunctional TF and development of the dry eye.
Keywords: Dry eye, ocular surface disease index score, pterygium, Schirmer's test, tear film breakup time
|How to cite this article:|
R. Gupta AK, Nathwani Y. Correlation between pterygium and dry eye. Kerala J Ophthalmol 2019;31:217-20
| Introduction|| |
Pterygium is a degenerative condition of the subconjunctival tissues which proliferate as vascularized granulation tissue to invade the cornea, destroying the superficial layers of the stroma and Bowman's membrane, the whole being covered by conjunctival epithelium. Various theories have been put forward to explain the etiopathogenesis of pterygia, but actual etiology still remains unexplained. Environmental factors such as ultraviolet rays , and chronic irritation to dust appears to be the dominant cause, but tear film (TF) abnormalities are also incriminated in its etiopathogenesis.,,
It is generally considered that TF instability in pterygium patients may arise from two major factors: chronic ocular surface inflammation and altered tear dynamics. Whether tear dysfunction is a precursor to pterygium or pterygium causes tear dysfunction is still not clear. Many studies have been performed to investigate the correlation between the occurrence of pterygium and dryness of the eyes.,,,,,,,,,, However, the correlation between the two from these studies is controversial.,,, It has been reported that pterygium itself could lead to a local conjunctival elevation and an uneven distribution of tear, resulting in dry eye with tear dynamics abnormality.,
Tear breakup time (TF-BUT) test introduced by Norn  is an excellent diagnostic test for detecting the mucin and lipid layer deficiency of the TF., Schirmer's test (ST) indicates the instability of the aqueous phase of the TF.,, Few studies from India have found abnormalities of tear function , in eyes with pterygia. The study aims to find the correlation between pterygium and dry eye in our tertiary center.
| Materials and Methods|| |
This case–control study included 50 patients attending the outpatient department of Ophthalmology, of a tertiary care hospital. The study was approved by the Institutional Ethics Committee, and written informed consent was obtained from the patients. Patients with unilateral primary pterygium and lack of any systemic diseases were included in the study. The other eye of the patient was taken as control. Patient with recurrent pterygium, bilateral pterygium, systemic diseases\syndromes associated with dry eye (e.g., Sjogren's syndrome), patient on systemic medication that leads to ocular drying, contact lens users, patients having any adnexal disease, anterior or posterior segment disease which alters tear secretion and stability, patients having recent ocular surgery (e.g., cataract surgery), and patients on topical anti-glaucoma medications were excluded from the study.
All the patients were subjected to detailed history taking with special attention to ocular dryness symptoms such as itching, burning sensation, foreign body sensation, watering, and discharge. Dry eye symptoms were assessed using the Ocular Surface Disease Index (OSDI) questionnaire. The total OSDI score was then calculated. The patients were subjected to a routine general physical examination, and a detailed ophthalmic examination. Slit-lamp examination was done to examine the anterior segment of the eye and to note the size of the pterygium. Size of the pterygium from the limbus to apex was taken by keeping the beam of slit lamp in the horizontal axis.
TF-BUT measurement with fluorescein was performed without topical anesthesia. Since instillation of anesthetic or any other topical drug could affect the TF, the TF-BUT was performed before performing any other test. The test was recorded after the eye was stained with fluorescein dye. The patient was then examined on the slit lamp and the time gap between the opening of the eyelid and the appearance of the first dry spot on the cornea was recorded using a stopwatch. Three readings were taken, and the mean value of the measurements was taken. A TF-BUT of <10 s was considered abnormal.
The ST was carried out without topical anesthesia bilaterally, with the standardized strips of filter paper, which was placed in the lateral canthus away from the cornea. The ST result was expressed as the wet length of the strip measured after 5 min. Readings were recorded in millimeters of wet strip. A ST of <10 mm was considered abnormal.
The symptom and intensity of dry eye were evaluated. The OSDI is a valid and reliable score for measuring dry eye disease severity (normal, mild to moderate, and severe), which was developed to assess the vision-related health-targeted quality of life with dry eye disease. The OSDI is assessed on a scale of 0-100, with higher scores representing greater disability. Based on this result, it can categorize patients as follows: normal ocular surface (0–12 units), mild ocular surface disease (13–22), moderate (23–32), and severe (33–100).
Test results were compared in the pterygium eye and contralateral normal eye of the same patient. Data were entered into Microsoft Excel, and SPSS 17 was used for statistical analysis. The paired t-test was used for analyzing the significance of the difference between case and control. The Pearson correlation was used to assess the correlations of tear BUT and ST with pterygium size. For all statistical evaluations, a two-tailed probability of value <0.05 was considered statistically significant.
| Results|| |
The study included 28 males and 22 females with a mean age of 47.04 years with the age range of 26–70 years. The maximum number of cases (44%) was between 41 and 50 years [Table 1].
The mean horizontal size of pterygium ± standard deviation (SD) was 2.35 ± 0.54 mm. The mean ± SD of TF-BUT in pterygium eyes was 7.1 ± 2.34 s compared with 9.18 ± 3.21 s in contralateral normal eyes (P < 0.05). The mean ± SDs of ST results in pterygium eyes and the opposite normal eyes were 8.96 ± 2.66 and 10.94 ± 3.88 mm, respectively (P < 0.05) [Table 2] and [Table 3].
In cases with pterygium size <1 mm, the mean TF-BUT and ST was 7.16 ± 1.69 s and 8.89 ± 2.61 mm and that of contralateral eye was 9.11 ± 3.14 s and 10.31 ± 3.46 mm respectively. In cases with pterygium size between 1 and 2 mm, mean TF-BUT and ST was 7.33 ± 2.19 s and 9.42 ± 2.70 mm and of the contralateral eye was 9.71 ± 3.60 s and 10.28 ± 3.70 mm, respectively. In cases with pterygium size >2 mm, mean TF-BUT and ST was 6.50 ± 3.29 s and 8.10 ± 2.25 mm and of the contralateral eye was 9.20 ± 4.48 s and 11.53 ± 3.74 mm, respectively [Table 1] and [Table 2]. On analysis, the difference in the mean TF-BUT between the pterygium eyes and the contralateral control eyes was significant for all sizes (P < 0.01). The difference in the ST between the pterygium eyes and the contralateral eyes was not significant for size <1 (P = 0.17) and 1–2 (P = 0.4) but was highly significant for size <2 mm (P < 0.001) [Table 2] and [Table 3].
Most patients with pterygium complained of mild-to-severe ocular discomfort. Mean OSDI was 30.6 ± 16.78.
| Discussion|| |
In this study, pterygium was more common in males and in the age group of 40–50 years. This may be related to the higher exposure to sunlight and dust as they are more involved in outdoor activities. Most patients with pterygium complained of mild-to-severe ocular discomfort. Mean OSDI was 30.6 ± 16.78.
In this study, the difference in the TF-BUT between the pterygium eyes and the contralateral control eyes was statistically significant (P < 0.05). This finding is consistent with Rajiv et al. and El-Sersy TH  who in their study found that pterygium cases had significantly reduced TF-BUT values, which caused inadequacy of TF. Similarly, Wang et al. and Manhas  also found that TF-BUT in the eyes with pterygium when compared with the opposite healthy eyes was significantly different. Ishioka et al. found that TF-BUT was shortened significantly in the eye with pterygium in unilateral cases. He concluded that there is a correlation between pterygium formation and shortened TBUT, and unstable TF may contribute to the initiation of pterygium.
In this study, the difference in the mean ST between the pterygium eyes and the contralateral control eyes was significant. Similar to our study of unilateral pterygium cases, Chaidaroon and Pongmoragot, Rahman et al., and Anthony et al., also reported that the ST was decreased significantly in the eye with pterygium. Whereas Biedner et al. performed ST in cases with unilateral pterygia and found no difference between the mean basic secretion of tears in the diseased eyes and the fellow eyes and suggested that dryness of the eyes cannot be regarded as the cause of pterygium. Roka et al. and Moreno et al. also found that ST values were lower among cases than their corresponding control eyes, whereas Bandyopadhyay et al. and Ergin A  did not find the difference in pterygium and control group and concluded that there were no tear function abnormalities in pterygium.
In this study, we evaluated the relationship between pterygium size and TF-BUT and STs. On analysis, we found that TF-BUT is reduced overall and is statistically significant (P < 0.05). The ST results showed statistically significant differences with different sizes of pterygium, which was more significant for size >2 mm [Table 1] and [Table 2]. Dissimilar to our findings Anthony et al. and Kampitak and Leelawongtawun  found that both tear BUT and ST results had no correlation with the horizontal size of pterygium. Dry eye is known to be caused due to environmental and habitual factors, but exposure to both the eyes to the environment remains the same. If there is unilateral pterygium, along with significantly more incidence of dry eye lateralized to the pterygium eye, as found in this study, it is suggested that pterygium appears to induce abnormal ocular surface conditions which leads to dysfunctional TF and development of the dry eye.
| Conclusion|| |
This study found that the TF-BUT and ST was decreased significantly in the eye with unilateral pterygium when compared with the contralateral normal eye. The size of pterygium showed a positive correlation with TF-BUT and ST results, indicating that pterygium was significantly associated with dry eye. Thus, the results of the present study strongly suggest that pterygium induces abnormal ocular surface conditions, which lead to dysfunctional TF and development of the dry eye.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]