Assessing subject-related variations of the Ocular Response Analyzer parameter calculation

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Background:

• The Ocular Response Analyzer (ORA) is a key tool for measuring intraocular pressure (IOP) and corneal hysteresis (CH).
• Understanding the variability in ORA parameter calculations is crucial for accurate clinical interpretation.

Purpose of the Study:

• To investigate the correlation between standard ORA output parameters and those derived from raw ORA data.
• To identify and quantify subject-specific variations in ORA parameter calculation procedures.

Main Methods:

• A prospective study involving six subjects and up to 32 ORA measurements per eye.
• Analysis of Goldmann-correlated IOP (IOPg) and corneal hysteresis (CH) using custom algorithms and statistical methods.
• Comparison of standard ORA outputs (IOPg, CH) with custom-calculated values (IOPg', CH') via regression analysis.

Main Results:

• Strong correlations were observed between standard IOPg and calculated IOPg', and between standard CH and calculated CH'.
• Significant subject-related differences were found in the regression slope parameters for both IOPg and CH calculations (p < 0.001).
• Group average IOPg was 11.6 ± 1.8 mmHg and CH was 10.7 ± 1.7 mmHg.

Conclusions:

• Subject-specific variations in ORA parameter calculations are evident.
• Current IOP estimation methods may involve undisclosed algorithms, potentially leading to biased results.
• Further research is needed to standardize ORA data processing and mitigate subject-related variability.