Original Research

Reliability of Schirmer and Phenol Red Thread test value on dry eye patients

Urvashni Nirghin, Tharuna Govender, Yeshalya Hirachund, Rorisang Mosololi, Hlengiwe Nxumalo, Sumaya Patel, Philani Zwane, Khathutshelo P. Mashige
African Vision and Eye Health | Vol 84, No 1 | a946 | DOI: https://doi.org/10.4102/aveh.v84i1.946 | © 2025 Urvashni Nirghin, Tharuna Govender, Yeshalya Hirachund, Rorisang Mosololi, Hlengiwe Nxumalo, Sumaya Patel, Philani Zwane, Khathutshelo P. Mashige | This work is licensed under CC Attribution 4.0
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 Africa
Tharuna 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

dry eye; Schirmer test; Phenol Red Thread test; reliability; intra-session; intersession

Sustainable Development Goal

Goal 3: Good health and well-being

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