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Published on: March 24, 2020
Assessing corneal hysteresis using the Ocular Response Analyzer
1School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia. c.mcmonnies@unsw.edu.au
Summary
Corneal hysteresis (CH) measurements using the Ocular Response Analyzer (ORA) may be influenced by various factors, not solely representing an intrinsic corneal property. Further research is needed for accurate clinical application.
Area of Science:
- Ophthalmology
- Biomechanical analysis
- Corneal physiology
Background:
- The Ocular Response Analyzer (ORA) is used to assess corneal biomechanical performance.
- Previous studies using ORA have raised questions about measurement variables and interpretation of findings.
- Corneal hysteresis (CH) is a key parameter assessed by ORA.
Purpose of the Study:
- To examine factors influencing corneal hysteresis (CH) assessment using the Ocular Response Analyzer (ORA).
- To identify additional variables that may affect CH measurements.
- To clarify the interpretation of ORA findings in relation to corneal biomechanics.
Main Methods:
- A PubMed search using keywords 'CH' and 'ORA' was conducted.
- English language articles relevant to the analysis were selected.
- References from selected articles were also reviewed.
Main Results:
- Corneal thickness, edema, intraocular pressure, and temperature are potential variables affecting CH.
- The area, location, rate, duration, and sequence of corneal unloading/loading are significant factors.
- These variables may influence the assessment of CH.
Conclusions:
- CH values might be specific to measurement conditions rather than an inherent corneal property.
- Uncontrolled variables can explain some ORA findings.
- ORA's CH measurement may represent 'central, applanation-derived hysteresis' due to its short unloading/loading sequence.
- Further understanding and development of ORA functions are needed for improved clinical management.
