This group of subjects were diagnosed with dry eye.

This group of subjects had no dry eye symptoms and signs and belonged to the normal control group.

The Ocular Surface Disease Index (OSDI; Allergan Inc., Irvine, CA)consists of a 12-item questionnaire and is used to assess dry eye disease; the OSDI questions are drawn from three different categories: vision-related functions, ocular symptoms and environmental triggers. The OSDI is scored on a 4-point scale from 0 (indicating no problems) to 4 (indicating a significant problem). Responses to all of the questions are combined to generate a composite OSDI score that ranges from 0 to 100, with higher OSDI scores representing greater disability. Subjects were asked questions regarding the dry eye symptoms that they experience.

The Schirmer I test (SIT) without anesthesia for tear secretion function was conducted by placing a 30-mm sterile Schirmer Tear Test strip into the junction of the middle and lateral thirds of the inferior fornix of each eye for 5 minutes. The wet portion of the strip was subsequently measured, with lower scores indicating less tear production.

The cornea was divided into upper, lower, nasal, temporal and central zones. Superficial punctate keratopathy (SPK) in the cornea was scored from 0 to 3 in each area. Where 0 indicated no staining in the cornea; 1,<5 punctate stains; 2,5-10 punctate stains; and 3,>10 or filamentous staining detected. The total score was recorded by adding the scores of the five zones for each eye (range: 0-15).

Noninvasive Tear Breakup Time (NI-TBUT) measurements of subjects' eyes were obtained by Keratograph 5. At the start of the recording, the patients were asked to blink three times and then keep their eyes open as long as possible. Irregularities in the reflected image indicated the instability of the tear film. Meanwhile, the examination was recorded on video and a single eye of each subject was assessed three times. All the tests were performeded the same temperature and humidity conditions.

Tear meniscus height was also performed by the Keratograph 5 and the image of tear meniscus height was obtained by the instrument. The observer measured the tear meniscus height the center of the lower lid margin. This evaluation was taken three times and the average value was recorded.