**2. Questionnaires**

Numerous questionnaires have been developed till date to study dry eye symptoms for many purposes such as diagnosis and quantification of DED, to study epidemiology of the disease, to assess effects of the treatment and its impact on the quality of life. The questionnaires are as follows-.

#### **2.1 Ocular Surface Disease Index (OSDI)**

It is a questionnaire consisting 12 questions, developed by the Outcome Research Group at Allergan which was designed for quick assessment of the symptoms of DED and their impact on vision related problems such as visual disturbance (poor vision or blurred vision) and visual function problems (difficulty in watching TV. working on a computer, driving at night and reading) [2].

The response to all the questions is graded on a scale of 0 to 4 -

a.none of the time

b.some of the time

c.half of the time

d.most of the time

e. all of the time

The following formula is then used to calculate the OSDI [3].

$$\text{OSDI} = \frac{(sum \text{of scores for all questions answered}) \times 100}{(\text{total number of questions answered}) \times 4} \tag{1}$$

A randomized study was performed on 68 patients admitted in ophthalmology Polyclinic of the Dumlupinar University from December 2005 to April 2006. Patients of 18 years and above were included in the study. The history taking and OSDI calculation was done by the same physician. Then after the routine ophthalmic assessment, the Schirmer test and TBUT were performed by another physician. The correlation analysis was done between Schirmer test, TBUT and OSDI scores. The patients were divided into 3 groups according to the OSDI scores and they are as follows-


#### *Diagnosis of Dry Eye DOI: http://dx.doi.org/10.5772/intechopen.98479*

The result showed there was a statistically significant difference between TBUT test scores of patients with low and high OSDI scores (p = .043), there was no significant difference between Schirmer test scores of the three groups. They concluded that although there is no internationally accepted criterion for the diagnosis of DED as of now, the OSDI is a standardized questionnaire to evaluate symptoms, and can easily be performed and used to support the diagnosis of DED [3].
