A Reliability and Validity of Thai Optotype Chart (SakThai Chart) on Visual Acuity Assessment
Keywords:
Reliability, Validity, Visual Acuity, Snellen Chart, Thai Visual Acuity TestAbstract
Objective: To examine the accuracy of the Thai Visual Acuity Test (SakThai Chart) for measuring visual performance.
Study Design: A cross-sectional study designed to test reliability and validity was conducted with 124 participants aged 20-65 years. These subjects voluntarily underwent visual acuity testing at the ophthalmology department of Thammasat University Hospital. The assessment involved reading both the numeric optotype chart and the Thai language visual acuity test (SakThai Chart) with the right eye, with subsequent result documentation. Data analysis was performed using SPSS version 25. The reliability of the instrument was evaluated using Pearson correlation, while validity was assessed through the Item-Objective Congruence (IOC) index and paired t-test.
Results: The Thai language visual acuity test (SakThai Chart) demonstrated a Pearson correlation coefficient of
0.992, indicating high reliability when compared to the Snellen Chart. Validity testing revealed IOC values exceeding
0.5 for all items. The paired t-test showed no statistically significant difference between the two instruments (P-value = 0.217).
Conclusion: The Thai language visual acuity test (SakThai Chart) exhibited high reliability with excellent correlation with numeric optotype chart. It demonstrated high content validity and can be considered a viable alternative to the numeric optotype chart for visual acuity assessment.
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