Dry Eye Disease and Pterygium

Material and Methods: Dry eye questionnaire (DEQ-6) was administered by a trained researcher and DE tests were performed in all 256 willing subjects (136 with pterygium+120 control) age 30-76 years, by a single surgeon under same physical conditions after taking the consent and approval from Hospital Ethical committee. Diagnosis was made on presence of both symptoms and tear film parameters. Statistical analysis by simple percentages.

terygium means a wing in Greek and it was first mentioned by Hippocrates. It is a fleshy, pink growth on the conjunctiva also called Surfer's eye. Both pterygium and pinguecula are abnormal growths on ocular surface 1 .
Pterygium has a worldwide distribution but it is common after exposure to ultraviolet radiations in warm and dry weather 2 . Sailors, skiers and sports people have a high incidence of pterygia due to reflected UV lights. Pterygium is also more common in New Zealand 3 in Ozone layer depletion areas.
Wolff in 1946, emphasized that meibomian glands are the proper glands of the cornea which have moved out of the way in the benefit of vision 4 . Smooth pre-corneal tear film formed after blinking protects the ocular surface to maintain quality of vision 5 .
The knowledge about Dry Eye diseases has improved during last decade. Dry eye is tear film disorder damaging interpalpebral ocular surface and causing unstable tear film 6 . Dry eye is also defined as a disturbance of lacrimal functional unit which consists of lacrimal glands, ocular surface including eyelids, meibomian glands, conjunctiva, cornea, goblet cells, and ocular nerves 7 .
Dry eye is a common disease, affecting about 5-30% of subjects aged 50 years and older (DEWS 2007) 6 . The Beaver Dam population based study reported incidence of 14% in adults over 48-91 years 8  Australia it is about 7% in elderly people 9 . In Indonesia it is 27.5% with more prevalence in older subjects, with pterygium and smokers 10 .
The purpose of this study was to find out the relationship between tear film changes and pterygium.

MATERIAL & METHODS
There were 136 patients of 30-76 years attending the eye OPD of Federal Government Services Hospital Islamabad from June 2013 to December 2014 having nasal pterygium and 120 normal volunteers of same age, gender and geographical distribution from refraction clinic who were selected and evaluated after taking their consent. Patients with any surgery, any systemic disease, lacrimal system disease, contact lens or drops use and refractive errors were excluded from the study.
1. Do your eyes ever feel dry? 2. Do you ever feel a gritty or sandy sensation in your eye? 3. Do your eyes ever have a burning sensation? 4. Are your eyes ever red? 5. Do you notice much crusting on your lashes? 6. Do your eyes ever get stuck shut in the morning? A 6 item standardized dry eye questionnaire (DEQ-6) (figure 1) was administered and scored by a trained researcher. Tear film breakup time (TBUT), Schirmer's test (ST), corneal fluorescein staining (CFS) for presence of conjunctival injection, punctate epithelial erosions (PEE) and meibomian gland dysfunction (MGD) were assessed by a single surgeon under the same physical conditions. The patients and controls were divided into two groups; group1 in whom both fluorescein break up time and Schirmer's tests were normal and group11 in whom either or both tests were abnormal. The eye with the larger pterygium was evaluated amongst bilateral pterygia. The diagnosis was made on the presence of three out of five parameters. All Data was entered into SPSS version 17 and analyzed for frequencies/percentages.

RESULTS
Of 256 subjects, age 30-76 years, 64.8% were urban, 69.9% were educated government servants, 22% were smokers and 29.6%were laborers. There were 19 (14.1%) subjects who showed pterygium in both eyes while 117 (85.9%) had pterygium in one eye (Table 1). Burning was the most common symptom reported among 91 (67%) patients in the case group. Both genders during the fourth decade had more numbers of pterygia. Moreover indoor workers were affected more in both groups ( Table 2).  Table 4.  It is common in the general population and progresses slowly but has little effect on vision. In our study most of the cases of pterygium were found in the fourth decade (40-49 years). It is similar to another study 12 . In advanced age excessive exposure to sun light causes the formation of pterygium. But, recent studies denied any relation of age with the pterygium incidence 13 .
In our study pterygium was seen more in patients with indoor activities contrary to the study of Viso et al, (2011) 14 . In Islamabad the indoor laborers (53%) suffered more than outdoor labourers (47%) with pterygium because in Islamabad they used to work 4-5 hours/day in the kitchen. Similarly, new studies denied any relationship between nature of work and pterygium 2 .
The tear film breakup time using fluorescein break is used to measure the tear film quality 15 . Our study indicated abnormal TBUT test in 62.2% of pterygium eyes and in 27.7% of eyes without pterygium. Another study reported reduced TBUT test in 30.3% of pterygium group and 21.9% eyes without that 16 . Another study reported TBUT instability in 39.7% eyes with pterygium and in 23% eyes without it 17 22 found that the mean goblet cell density was increased 1 month after excision. Moreover, Ye et al reported that both tear film break-up time and Schirmer test were different in study and control groups similar to our study 23 .
In the literature no cases of pterygium were found in children below the age of 5 years. This study revealed that 67% males were more affected than 33% females. One Study 2 noticed no gender dependence. Another study from rural Dali in China noticed an increased pterygium formation in females than men 24 . The lifestyle of labor between the genders may be the reason. A study by Peng et al in Tibet reported that women were at a higher risk than men related with their lifestyle. In Tibet, women were more often involved in outdoor activities and jobs 25 .
It has been found that excessive use of drops containing preservatives can destroy goblet cells and the ocular surface resulting in DE 16 . A pterygium induces astigmatism if larger than 3 mm. More than 3.5 mm lesions can result in more than 1 D of astigmatism causing blurring of vision. Also interestingly our study showed that the prevalence of pterygium increased with age until 69 years of age and then declined similar to another study 26 . In this study 51% subjects showed lid plugging and mucous threads. This mucus pattern brings changes in the Pakistan Journal of Ophthalmology ocular surface. Mucin reduces the surface tension of tears and increases the wettability of the hydrophobic lipoprotein epithelial surface 23 . This study was done to know the dry nature of the eyes having pterygium. Other studies have proved that pterygium excision improved tear osmolarity and tear film functions which were deteriorated again with the recurrence of pterygium 26 .
In this study when normal subjects were compared with pterygium patients, both tear film breakup time and Schirmer's test showed changed values. The tear film changes cause dellen formation leading to focal dryness.
The limitation of our study was that it was conducted in a single center. Further studies need to be done with larger sample size to improve the generalizability of the results.

CONCLUSION
There is a relation between tear film functions, ocular surface changes and pterygium. The function of Meibomian gland is derranged in pterygium patients which initiates dellen formation which leads to dryness. Pterygium disturbs tear functions causing dry eye like symptoms.