Original Research
Reliability of Schirmer and Phenol Red Thread test value on dry eye patients
Submitted: 15 May 2024 | Published: 29 January 2025
About the author(s)
Urvashni Nirghin, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South AfricaTharuna Govender, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Yeshalya Hirachund, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Rorisang Mosololi, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Hlengiwe Nxumalo, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Sumaya Patel, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Philani Zwane, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Khathutshelo P. Mashige, Department of Optometry, Faculty of Health Science, University of KwaZulu-Natal, Durban, South Africa
Abstract
Background: The repeatability of the Schirmer test (ST) and Phenol Red Thread test (PRT) has been investigated thoroughly on patients with normal tear function; however, it is limited to dry eye patients.
Aim: This study aimed to compare the reliability of the ST and PRT on young adults with dry eyes.
Setting: University of KwaZulu-Natal Eye Clinic.
Methods: Forty-eight young adults (mean age 20.65 ± 1.71 years) participated in the study. Preliminary tests excluded dry eye-related abnormalities. Novesin (0.4%) was instilled into the right eye of each participant, followed by the administration of the ST and PRT, 5 min apart, then re-administered after a 10-min interval. The retest was conducted 1 week later with the PRT being performed first to minimise bias.
Results: The intra-session correlation of the ST and the PRT was poor (ICC < 0.5) and the difference was statistically significant (P < 0.05). The inter-session correlation for the PRT was poor (ICC = 0.432) while the ST was moderate (ICC = 0.567) with no statistical difference observed for all parameters (P < 0.05). The Bland–Altman plots for intra- and inter-session indicate that 96% of observations fell within the 95% limits of agreement.
Conclusion: The ST and PRT demonstrated good intra-session and inter-session reliability, with ST showing better inter-session agreement than the PRT.
Contribution: The ST and the PRT provide consistent and reproducible results on dry eye patients when conducted on the same individuals at different time points.
Keywords
Sustainable Development Goal
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