Evaluation of Phenol Red Thread test versus Schirmer test in dry eyes: A comparative study

BACKGROUND: Dry eye is the most common ocular morbidity found in elderly patients. There is no gold standard/standard test for diagnosing dry eye. OBJECTIVES: The present study was conducted to compare the potential of Phenol Red Thread (PRT) test versus Schirmer Test in diagnosing dry eye. MATERIALS AND METHODS: The study was conducted on 50 patients, aged 40 years and above. History of dry eye symptoms was taken and the symptoms were graded. Six-questions Bandeen Rosch questionnaire was administered to those having symptoms of dry eye. Patients whose response to any of the questions was often/all the time were included in the study. After performing standard clinical examination, Schirmer and PRT tests were done. RESULTS: PRT is equally sensitive in detecting dry eye, and in addition, it has many advantages as compared to Schirmer. PRT is simpler and more comfortable to the patient and can be done in children. It causes less reflex tearing. Most important is the lesser time consumed (15 seconds) in comparison to Schirmer (5 minutes). CONCLUSION: Kappa value between PRT and Schirmer was found to be 0.96 in this study and shows a strong agreement between the two. So, PRT can be considered equally good in detecting dry eye.