Intra- and intersession repeatability of a double-pass instrument

Area of Science:

• Ophthalmology
• Optical Engineering
• Biomedical Instrumentation

Background:

• The Optical Quality Analysis System (OQAS) utilizes the double-pass technique to assess ocular optical quality.
• Accurate and repeatable measurements are crucial for clinical evaluation of visual function.

Purpose of the Study:

• To evaluate the intra- and intersession repeatability of optical quality parameters obtained using the OQAS.
• To determine the impact of eye realignment on measurement variability.

Main Methods:

• OQAS measurements were performed on 20 healthy eyes (best spectacle-corrected visual acuity ≥ 20/20).
• Examinations were conducted across three separate sessions with 10-minute intervals, including eye realignment at each session start.
• Within each session, three consecutive measurements were taken without realignment.
• Analyzed parameters included MTFcutoff, Strehl ratio, OQAS values (OV) at various contrasts, and objective scatter index (OSI).

Main Results:

• Mean coefficients of repeatability for intra- and intersession measurements were consistent across all analyzed parameters (MTFcutoff, Strehl ratio, OV at 100%, 20%, 9%, and OSI).
• Bland and Altman analysis showed confidence limits indicating good agreement for both intra- and intersession repeatability.
• No significant additional variability was introduced by eye realignment between sessions.

Conclusions:

• The OQAS is a reliable clinical instrument for assessing ocular optical quality.
• The system exhibits good intra- and intersession repeatability.
• Eye realignment does not significantly affect the variability of OQAS measurements.