What can cause discrepancies in keratometer readings?

Discrepancies in keratometer readings can arise from several factors, and the correct answer encompasses all of them.

Fluctuations in the tear film can significantly affect keratometer readings. The tear film is crucial for providing a smooth optical surface over the cornea; variability in its thickness or stability can alter the light reflection and lead to inconsistent measurements.

Using an outdated keratometer is another factor contributing to discrepancies. Older instruments may not have the advanced technology needed to provide accurate readings or might not be well-calibrated, potentially leading to errors in measurement.

Patient movement during the measurement process can also cause inaccuracies. Any slight shifting of the patient's gaze or position while the reading is taken can lead to incorrect alignment and therefore affect the results.

Since all of these factors are valid sources of discrepancies in keratometer readings, it is essential to consider them collectively to understand the variabilities that can occur during measurement.