Pterygium is a conjunctival disorder that can occur across different stages of life. It is more prevalent and severe in tropical regions near the equator, while in cooler climates it tends to be less common and milder. The main risk factors include hot and dry environments, along with prolonged exposure to ultraviolet (UV) radiation. Reported prevalence rates vary between 6% and 34%, with a prevalence of 5.2% documented in India.1 Recent theories emphasize limbal stem cell deficiency as a potential mechanism underlying pterygium development.2,3 The prevalence of dry eye disease (DED) ranges from 14.4% to 33%.4 Tear function abnormalities have been suggested as a contributing factor in pterygium pathogenesis, as pterygium progression is often aggravated by elevation of the pterygium head, dryness, and dellen formation. A possible mechanism linking pterygium and DED is the alteration of corneal biomechanical properties caused by pterygium. While tear dysfunction may predispose to pterygium growth, it remains debated whether pterygium itself contributes to tear dysfunction. In this context, the present study aimed to evaluate the relationship between pterygium size and tear film status, using tear film breakup time (TF-BUT) and Schirmer’s test (ST).

An observational study was conducted among patients attending the outpatient ophthalmology department. The study was approved by the Institutional Ethics Committee, and written informed consent was obtained from all participants. Selection criteria: Inclusion: Patients aged 26–70 years with unilateral primary pterygium, without systemic diseases, and who provided informed consent. Exclusion: Patients with bilateral or recurrent pterygium, systemic diseases or syndromes associated with dry eye (e.g.,Sjögren’s syndrome), those on systemic medications known to cause ocular dryness, contact lens users, patients with adnexal, anterior or posterior segment disorders affecting tear secretion or stability, recent ocular surgery (e.g., cataract surgery), those using topical anti-glaucoma medications, or those unwilling to provide consent. Procedure: A total of 100 patients (26–70 years) were enrolled. Dry eye symptoms were evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. All patients underwent a routine physical examination and comprehensive ophthalmic evaluation. The anterior segment was examined under slit lamp biomicroscopy to assess pterygium size. Tear film status was assessed using tear film breakup time (TF-BUT) and Schirmer’s test (ST), comparing the pterygium eye with the contralateral normal eye of the same patient. TF-BUT: Fluorescein dye was instilled, and under slit-lamp examination, the time interval between the last blink and the appearance of the first dry spot was recorded using a stopwatch. Three readings were obtained, and the mean value was calculated. A TF-BUT ≤10 seconds was considered abnormal. Schirmer’s test: Performed bilaterally without topical anaesthesia, using standardized filter paper strips placed in the lateral canthus away from the cornea. Wetting was measured in millimetres after 5 minutes. A reading ≤10 mm was considered abnormal. The OSDI score was used to classify dry eye severity: normal (0–12), mild (13–22), moderate (23–32), and severe (33–100). Higher scores indicated greater disability. Statistical analysis: TF-BUT and ST results were compared between pterygium and contralateral normal eyes using the paired t-test. The relationship between tear film parameters (TF-BUT and ST) and pterygium size was analyzed using Pearson correlation.

Table 1. Distribution of Demographics, Complaints in case and control group. Age (Yrs) Cases Control P value 21 – 30 12 26 0.05 31 – 40 22 30 41 – 50 29 18 51 – 60 24 14 61 – 70 13 10 Sex Male 53 54 0.08 Female 47 46 Complaints Burning 38 36 >0.05 Redness 36 30 >0.05 Watering 72 30 <0.0001 Dryness 25 38 <0.05 Dimunition of vision 29 14 <0.01 Foreign body sensation 26 34 >0.05 Lid crusting 0 8 <0.01 Encroaching mass 31 0 <0.0001 None 0 18 <0.0001 • The mean Schirmer’s test (ST) values in pterygium eyes and contralateral normal eyes were 8.5 ± 2.24 mm and 12.8 ± 5.37 mm, respectively (P < 0.0001).  In cases with pterygium >2 mm, the mean TF-BUT and ST in affected eyes were 8.5 ± 2.24 s and 9.95 ± 3.5 mm, while in contralateral normal eyes, they were 12.8 ± 4.1 s and 15.4 ± 4.6 mm.  The difference in mean TF-BUT between pterygium eyes and contralateral control eyes was significant across all pterygium sizes (P < 0.01).  The mean Ocular Surface Disease Index (OSDI) score was 31.5 ± 15.98, indicating that the majority of patients experienced mild to severe ocular discomfort. Table 2. Comparison of Schirmer’s test and TF-BUT in case and control Parameter Cases Control Z Value P Value Mean ± SD (n=100) Mean ± SD (n=100) Tear film break up time (sec) Size of pterygium < 1mm 7.96 ± 2.24 9.68 ± 3.99 2.1 0.001 1-2mm 8.6 ± 2.8 13.75 ± 3.5 1.85 < 0.001 >2mm 8.9 ± 2.5 12.8 ± 4.1 2.0 0.002 Total Mean 8.5 ± 2.24 12.85 ± 3.7 2.29 <0.001 Schirmer’s test (mm) Size of pterygium < 1mm 9.92±3.2 14.31±3.46 1.85 0.08 1-2mm 10.89±3.61 14.2±4.5 2.1 0.10 >2mm 9.95±3.5 15.4±4.6 1.22 0.02 Total Mean 10.1 ± 3.45 14.9 ± 4.1 1.35 0.04  The mean tear film breakup time (TF-BUT) in pterygium eyes was significantly lower than in contralateral normal eyes for all sizes of pterygium (P < 0.01).  The mean Schirmer’s test (ST) values showed no significant difference between pterygium and contralateral eyes for sizes <1 mm and 1–2 mm, but were significantly lower in pterygium eyes with sizes >2 mm.  The mean Ocular Surface Disease Index (OSDI) score was 32.8 ± 14.9, indicating that most patients experienced mild to severe ocular discomfort. Table 3. Tear film status wise distribution of cases in case and control group Tear film status Cases Control Chi-square P value Abnormal 35 32 0.19 0.085 Normal 65 68

This study investigated the relationship between pterygium size, tear film breakup time (TF-BUT), and Schirmer’s test (ST) values. The incidence and severity of pterygium and dry eye disease (DED) vary widely worldwide, with higher prevalence in tropical and subtropical regions, particularly among individuals exposed to sun, wind, and dust.5,6,7 In the present study, the majority of patients in the pterygium group were aged 41–50 years, while the control group was mainly 31–40 years. Age was a significant factor, reflecting cumulative environmental exposure. This finding aligns with previous studies reporting that most pterygium cases occur in individuals aged 30–40 years.8,9,10 Gender differences were also observed, with males showing a higher prevalence of pterygium and dry eye. This may be attributed to greater occupational and outdoor exposure to adverse environmental conditions. Clinically, early pterygium is often asymptomatic but can occasionally cause dry eye symptoms and visual disturbances due to induced astigmatism or obstruction of the visual axis. In this study, the most common complaints included watering, dryness, blurred vision, lid crusting, and a mass encroaching on the cornea. A significant relationship was observed between pterygium and corneal astigmatism, consistent with prior reports.11-14 Tear film analysis revealed that TF-BUT values were significantly reduced in pterygium eyes compared to contralateral normal eyes (p<0.0001), indicating unstable tear films. This aligns with previous studies showing lower TBUT and marginal tear meniscus levels in pterygium patients, reflecting functional tear film compromise. Schirmer’s test values were reduced in pterygium eyes, though the difference was not statistically significant for smaller pterygium sizes (<1 mm and 1–2 mm), but significant for pterygium >2 mm.15 Patients with decreased tear production are more susceptible to the damaging effects of UV exposure, supporting a link between dry eye and pterygium. The study found that patients with abnormal tear film status (TF-BUT <10 s and ST <10 mm) had an odds ratio of 1.14, indicating a slightly increased risk of pterygium in dry eye patients. These findings are consistent with previous research. Rajiv et al. and El-Sersy TH reported significantly reduced TF-BUT in pterygium cases, reflecting tear film inadequacy.8,16 Other studies demonstrated lower mean tear meniscus height, Schirmer’s test, and TBUT in pterygium patients, with strong correlations between ocular surface abnormalities, irritation, and tear film instability.16 Dry eye prevalence was higher in pterygium cases (54%) compared to controls (26%), supporting a strong association between pterygium and dry eye. The study also highlighted that TF-BUT is reduced overall across all sizes, while ST differences were significant only for pterygium >2 mm. Some studies reported no correlation between horizontal pterygium size and tear film parameters, suggesting that environmental and habitual factors contribute to dry eye. Pterygium itself may exacerbate ocular surface dysfunction, leading to tear film instability and dry eye development.17-20 In conclusion, this study confirms a significant association between pterygium and tear film instability, particularly in larger lesions, and underscores the importance of assessing both TF-BUT and Schirmer’s test in patients with pterygium. Environmental exposure, age, and male gender appear to be important risk factors.21,22

A strong relationship exists between ocular irritation symptoms, surface abnormalities, and functional evidence of tear film instability. Simple diagnostic tests, such as Schirmer’s test and tear film breakup time (TF-BUT), can serve as effective initial screening tools in the outpatient setting to detect tear film abnormalities in patients with pterygium. Furthermore, pterygium size was positively correlated with TF-BUT and ST, indicating that larger pterygia are significantly associated with dry eye syndrome.

1. Valim V, Trevisani VF, de Sousa JM, Vilela VS, Belfort R Jr. Current approach to dry eye disease. Clin Rev Allergy Immunology 2015;49:288-97 2. Singh MM, Murthy GV, Venkatraman R, Rao SP, Nayar S. A study of ocular morbidity among elderly population in a rural area of central India. Indian J Ophthalmol. 1997;45(1):61–5. 3. Detorakis ET, Spandidos DA. Pathogenetic mechanisms and treatment options for ophthalmic pterygium: trends and perspectives (Review). Int J Mol Med. 2009;23(4):439–47 4. Lee AJ, Lee J, Saw SM, Gazzard G, Koh D, Widjaja D, et al. Prevalence and risk factors associated with dry eye symptoms. Br J Ophthalmol. 2002;86:1347–51. 5. Paton D. Pterygium management based upon a theory of pathogenesis. Trans Am Acad Ophthalmol Otolaryngol. 1975;79:603–12 6. Kotecha MR, Paranjpe RR, Manade VV, Gotecha SS. A clinical study of correlation between pterygium and dry eye. Indian J Clin Exp Ophthalmol 2021;7(4):736-740 7. Schiffman RM, Christianson MD, Jacobsen G, Hirsch JD, Reis BL. Reliability and validity of the ocular surface disease index. Arch Ophthalmol 2000;118:615 21. 8. Rajiv, Mithal S, SoodAK. Pterygium and dry eye –A clinical correlation. Indian J Ophthalmol 1991;39:15 6. 9. DJ Pandey VK Mishra DN Pandey Relationship between pterygium and lacrimation - a clinical studyIndian J Ophthalmol198331106870 10. H Shiroma A Higa S Sawaguchi A Iwase A Tomidokoro S Amano Prevalence and Risk Factors of Pterygium in a Southwestern Island of Japan: The Kumejima StudyAm J Ophthalmol2009148576671 11. SR Durkin S Abhary HS Newland D Selva T Aung RJ Casson The prevalence, severity and risk factors for pterygium in central Myanmar: the Meiktila Eye StudyBr J Ophthalmol2008921259 12. G Gazzard SM Saw M Farook Pterygium in Indonesia: Prevalence, severity and risk factorsBr J Ophthalmol2002861213416 13. SE Moss R Klein BE Klein Prevalence of and risk factors for dry eye syndromeArch Ophthalmol2000118912648 14. OD Schein B Munoz JM Tielsch KB Roche S West Prevalence of dry eye among the elderlyAm J Ophthalmol19971247238 15. SC Kadayifcilar M Orhan M Irkee Tear functions in patients with pterygiumActa Ophthalmol Scand19987621769 16. El Sersy TH. Role of pterygium in ocular dryness. J Egypt Ophthalmol Soc 2014;107:205 8. 17. M Saleem L Muhammad Z Islam Pterygium and dry eye- a clinical studyJPMI200418455862 18. N Roka SP Shrestha Assessment of tear secretion and tear film instability in cases with pterygium and normal subjectsNepal J Ophthalmol2013591623. 19. Chaidaroon W, Pongmoragot N. Basic tear secretion measurement in pterygium. J Med Assoc Thai 2003;86:348 52. 20. Rahman A, Yahya K, Fasih U, Waqar ul Huda, Shaikh A. Comparison of Schirmer’s test and tear film breakup time test to detect tear film abnormalities in patients with pterygium. JPak Med Assoc 2012;62:1214 6. 21. Antony AT, Mini PA, Dalia S. Pterygium and dry eye a clinical correlation. J Med Sci Clin Res 2017;5:23654 9. 22. Kampitak K, Leelawongtawun W. Precorneal tear film in pterygium eye. J Med Assoc Thai 2014;97:536 9.