Dry Eye Syndrome. A Diagnostic Enigma

Purpose: To compare routine tear function tests and conjunctival impression cytology (CIC) in patients with dry eye syndrome, and to determine the sensitivity, specificity and positive predictive values of these tests, considering CIC as the gold standard? Material & method: A case control prospective study was done. The eyes of 276 patients with dry eyes, was compared with 216 eyes of controls. Patients were enrolled on basis of a questionnaire of common symptoms of dry eye. Tear film break up time (TBUT), Schirmer's-1, Rose Bengal scores (RBS) were compared with impression cytology scores. Results: The mean Schirmer's value in cases was 12.54 ± 4.73 and 16.32 ± 3.80 in controls (P=0.000). The mean tear film break up time in cases was 9.11 ± 2.90 and 14.21 ± 2.72 in controls (P=0.00). The mean goblet cell density in cases was 476 ± 238 and 1552 ± 598 in controls (P=0.000). 46.7% cases of dry eye had abnormal CIC as compared to 32.8 % controls. The sensitivity of tear function tests in diagnosing dry eye was TBUT>Schirmer's>RBS and specificity was Schirmer's>TBUT>RBS in decreasing order, taking CIC as gold standard. Conclusions: Dry eye diagnosis remains a diagnostic enigma. Routine tear function tests lack sensitivity and specificity. Therefore, they should be used in combination with tests like conjunctival impression cytology to improve diagnostic accuracy.