Clinical evaluation of the Oculus Keratograph

Area of Science:

• Ophthalmology
• Optometry
• Biomedical Optics

Background:

• Accurate measurement of corneal curvature and tear film stability is crucial for diagnosing and managing ocular surface diseases.
• The Oculus Keratograph is a device used for assessing these parameters, but its clinical validity and reliability require thorough investigation.

Purpose of the Study:

• To evaluate the validity and reliability of corneal curvature and non-invasive tear break-up time (NITBUT) measurements obtained using the Oculus Keratograph.
• To compare Keratograph measurements with established devices and assess their correlation with patient-reported symptoms.

Main Methods:

• Corneal curvature was measured using the Oculus Keratograph and Nidek ARKT TonorefII in 100 eyes.
• Non-invasive tear break-up time (NITBUT) was assessed objectively with the Keratograph and subjectively with the Keeler Tearscope.
• Repeatability of Keratograph measurements and correlation with the Ocular Surface Disease Index (OSDI) were analyzed.

Main Results:

• The Keratograph reported significantly flatter corneal curvatures compared to the Nidek ARKT TonorefII but demonstrated good repeatability.
• Keratograph NITBUT measurements were significantly lower than Tearscope assessments and showed a decrease on repeat measurements.
• A higher percentage of subjects had NITBUTs below 10 seconds when measured by the Keratograph.
• Tearscope results showed a better correlation with patient symptoms than Keratograph measurements.

Conclusions:

• The Oculus Keratograph requires a calibration offset for accurate comparison with other keratometry devices.
• The current Keratograph software detects very early tear film changes, resulting in lower NITBUT values than subjective methods.
• Software adjustments could improve the clinical utility of the Keratograph's objective tear film assessments.