|Year : 2023 | Volume
| Issue : 1 | Page : 55-58
Evaluation of changes in ocular surface disease index score and meibomian gland parameters in primary pterygium
Radha Mathur, Chander Ashish, Rastogi Priye Suman
Department of Ophthalmology, TMMC and RC, Moradabad, Uttar Pradesh, India
|Date of Submission||13-Mar-2022|
|Date of Decision||29-Aug-2022|
|Date of Acceptance||10-Dec-2022|
|Date of Web Publication||21-Feb-2023|
Department of Ophthalmology, TMMC and RC, Moradabad, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
BACKGROUND: Pterygium is a commonly occurring ocular pathology, characterized by a benign proliferation of conjunctiva which extends onto the corneal surface. Abnormal tear film and meibomian gland (MG) dysfunction have been linked to pterygium development.
AIMS: This study was done to evaluate the changes taking place in the Ocular Surface Disease Index (OSDI) score and other tear film parameters with MG parameters in patients of primary pterygium as well as evaluation of the relation between them in pterygium.
SETTINGS AND DESIGN: This was a case–control study, done in a tertiary care hospital in North India.
MATERIALS AND METHODS: Patients presenting to the ophthalmology outpatient department with a diagnosis of pterygium were enrolled in the pterygium study group along with their gender- and age-matched controls. Both groups were evaluated for OSDI score and other tear films and MG parameters were compared.
STATISTICAL ANALYSIS USED: The results were analyzed using SPSS version 24.0. A P < 0.05 was considered statistically significant.
RESULTS: The OSDI score was significant among the study groups with a P = 0.006 and the MG parameters of MG expression score, lid margin abnormality, and meiboscore were also significant with a P = 0.002, 0.002, and < 0.01, respectively.
CONCLUSIONS: There is a positive association between pterygium, tear film abnormality, and MG disease (MGD). A strong association was also established between MGD and dry eye. Any alteration in one will aggravate the other.
Keywords: Dry eye, meibomian gland, meibomian gland dysfunction, pterygium, tear film
|How to cite this article:|
Mathur R, Ashish C, Suman RP. Evaluation of changes in ocular surface disease index score and meibomian gland parameters in primary pterygium. Oman J Ophthalmol 2023;16:55-8
|How to cite this URL:|
Mathur R, Ashish C, Suman RP. Evaluation of changes in ocular surface disease index score and meibomian gland parameters in primary pterygium. Oman J Ophthalmol [serial online] 2023 [cited 2023 Mar 26];16:55-8. Available from: https://www.ojoonline.org/text.asp?2023/16/1/55/370061
| Introduction|| |
Pterygium is a fibrovascular and subepithelial ingrowth of the degenerative bulbar conjunctiva. It is a “wing-shaped” lesion of the conjunctiva which encroaches the cornea and can be easily diagnosed on clinical examination.
It occurs worldwide, most commonly in the “Pterygium belt” zone of tropical countries with a prevalence of 12%.
Ultraviolet exposure is an important risk factor for pterygium development.
Studies done on pterygium have suggested a tear film abnormality associated with pterygium development. However, it has not been clear if the pterygium is responsible for tear film abnormality or vice versa.
Meibomian gland disease (MGD) has also been linked with pterygium. It has been suggested that ocular discomfort arises as a result of abnormal functioning of the MGs.
The association between pterygium and tear film function and MGD has been difficult to explain. This can be due to the variation in the incidence of pterygium globally.
This study was done to evaluate the Ocular Surface Disease Index (OSDI) score and the changes taking place in the MGs in patients with primary pterygium.
| Subjects and Methods|| |
This case–control clinical study was conducted after clearance from the Institutional Ethical Committee IEC/19-20/091.
Sample size and formula
The sample size was calculated using the formula:
n = (r + 1)/r × σ2 (Zβ + Zα/2)2/(mean difference)2
Where r = ratio of cases and controls
σ = Standard deviation (SD) of the outcome variable
Zβ = desired power
Zα/2 = desired level of statistical significance
Mean difference = 1.6
As per this formula, 50 cases and 50 controls were taken for the study.
All patients coming to the outpatient department of ophthalmology with a diagnosis of primary pterygium were enrolled in the study after fulfilling the inclusion and exclusion criteria. Written informed consent was obtained from each patient after explaining them the study in detail.
The case group consists of patients with age more than 18 years with a diagnosis of primary pterygium.
The control group consists of gender- and age-matched controls of pterygium cases which comparing patients with primary pterygium with the normal population.
Patients with any ocular cicatricial disease/comorbid ocular diseases, history of contact lens use, history of using ocular topical medications, any systemic illness affecting MG function or dry eye, or patients not willing to give consent were excluded from the study.
Initial workup included detailed history with best-corrected visual acuity using Snellen's chart, along with slit-lamp examination of the adnexa, anterior and posterior chambers, and detailed examination of pterygium.
After the initial workup, the following criteria were assessed:
- Tear film break-up time (TBUT) – evaluated by placing a dry fluorescein strip to the inferior fornix with the patient looking up. The cornea was then scanned using blue Cobalt filter of the slit lamp. The time of appearance of the first dry spot measured the TBUT. Time <10 s was considered abnormal
- Schirmer test – performed by placing a standard Whatman No. 41 Schirmer test I Filter Paper strip in the mid-lateral portion of the lower fornix. The amount of wetting was recorded after 5 min
- OSDI – patients were asked a series of questions from a validated questionnaire and their response was noted. The total score was evaluated as per the interpretation given by the OSDI score (scale of 0–100)
- MG expression – assessed by assigning grades for clarity and ease of meibum expression in a region of the eyelid using a slit lamp. Grading was done as per the MG expression score from a scale of 0–4
- Lid margin abnormality – lid margin was checked for vascular engorgement, plugging of the MG, displacement of the mucocutaneous junction, and any irregularity of lid margin. Total score of each patient – compared and evaluated
- Meiboscore – obtained for both upper and lower lids by assessing the area of MG loss with the help of a slit lamp. Score 0–3 for each lid.
The recordings were collected and statistical analysis was done with done with “Statistical Package for the Social Sciences” (2016) version 24.0, developed by IBM and released by the University of Stanford, USA. A P < 0.05 was considered to be statistically significant.
| Results|| |
The study was done in a tertiary care hospital in India. It included 50 pterygium cases and 50 of their gender- and age-matched controls. It comprised 70% male population with the remaining 30% female population among the study groups.
[Table 1] shows the mean and SD values of the tear film parameters documented from the study. The P value of the OSDI score was 0.006, value of TBUT was <0.01 and 0.031 for right and left eyes, respectively, and the value for Schirmer test was 0.023 and 0.10 for right and left eyes, respectively. These findings are suggestive of remarkable changes in the tear film parameters in patients with primary pterygium.
From the clinical presentation of the patients along with their respective tear film parameters, dry eye was found to be present only in a minor fraction of the study groups irrespective of the presence of pterygium. [Table 2] shows the distribution of dry eye among the study groups with a P = 0.33 which was not found to be statistically significant.
The MG parameters were found to be statistically significant in the study. [Table 3] shows the mean and SDs of the MG parameters. The P value of MG expression score was significant with a value of 0.002, the value of lid margin abnormality was also 0.002 and the value of meiboscore was significant with <0.01.
Along with the association of tear film and MG parameters with pterygium, our study also established a correlation between these variables. [Table 4] illustrates that there was a significant negative correlation between the MGD parameters of MG expression score, lid margin abnormality, and meiboscore with TBUT and Schirmer test among both study groups. A significant positive correlation was found between the MGD parameters with OSDI score among both study groups.
|Table 4: Correlation between tear film and meibomian gland parameters in the pterygium group|
Click here to view
| Discussion|| |
Pterygium is a common ocular pathology found in areas prone to hot and humid climates. It causes a wide range of clinical features ranging from mild cosmetic blemishes to severe visual impairment.
Pterygium is often associated with disturbances in the normal tear function and abnormalities of the MGs.
Tear film parameters and pterygium
The tear film serves as an interface of the ocular surface with the environment.
The TBUT denotes the time taken for the first dry spot to appear on the ocular surface. The P < 0.01 and 0.031 for the right and left eyes, respectively, which were statistically significant. Our results indicate a decrease in the TBUT values of pterygium cases as compared with the normal. There are other studies which support this result. However, their values were statistically significant with a P < 0.001 and < 0.01, respectively.,
The Schirmer test values assess the tear function and its quantity. Our study reported a fall in the Schirmer test values in the pterygium groups when compared to the normal groups, but the values were not abnormally low. Only a few similar studies have been done but they showed variable results.
The OSDI score demonstrates sensitivity and specificity in distinguishing between normal patients and those with dry eyes. The P value was 0.006 which was statistically significant. From the above results, it can be concluded that in our study, cases with pterygium had moderate changes and the control group is within the normal limit.
Observing the results of the above parameters from our study, only 26% of pterygium cases were diagnosed with dry eye disease. Seventy-four percent of cases did not qualify to be diagnosed as those with dry eye disease. In comparison, only 18% of the control group presented with dry eye disease, whereas 82% of cases of the control group showed the absence of dry eye disease. The P value was 0.33, which was not statistically significant.
Meibomian gland parameters and pterygium
MGs play an important part in the ocular defense mechanism, thereby protecting it from various environmental factors.
The MG expression score quantifies the ease of meibum expression from the MGs. The MG expression score of our study group had a P = 0.002, which was statistically significant. This finding correlated with the ocular symptoms and was suggestive of increase in the difficulty of expression of meibum from the MGs.
The lid margin abnormality score measured any signs of abnormality in the upper as well as the lower eyelids. The score among the cases and controls had a P = 0.002 which proved that significant pterygium cases had associated lid abnormalities.
Meiboscore measured the area of MG loss or dropout in each eyelid. It was statistically significant in our study population with a P = 0.01. Similar results had been concluded by Wu et al.
Correlation between tear film and meibomian gland parameters
According to our study, the link between the MG and dry eye parameters was found to be variable.
| Conclusion|| |
A negative correlation was found to be associated between MG expression score with TBUT and Schirmer test. Similar significant negative correlation was found between meiboscore with TBUT and Schirmer test and between lid margin abnormality and TBUT and Schirmer test.
Conversely, the correlation of OSDI score with MG parameters was a significantly positive one.
These findings conclude that as MGD produces significant changes in the normal functioning of the MG in both groups, the TBUT and Schirmer test values are decreased and the OSDI values are increased, causing a dry eye state.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]