What do you see when the keratometer is out of focus on the cornea?

When the keratometer is out of focus on the cornea, it typically results in specific visual cues that indicate improper calibration or alignment. In this scenario, if the lower right mire appears doubled, it signifies that the focus is misaligned, causing an overlap of the reflected mire patterns.

This doubling of the mire specifically indicates that one meridian is more in focus than the other, leading to distortion in visual perception. The correct alignment would show distinct single reflections of the mires, which allow for accurate measurement of the corneal curvature. Therefore, the presence of doubled mires, particularly in the lower right section, is a key indicator that adjustments or refocusing are necessary for proper keratometric reading.

Other visual symptoms, such as blurriness or misalignment of the upper mired areas, could arise in different contexts of focus, but in this case, the doubling specifically signals that focus issues are occurring in the lower right mire and suggests that further assessment and adjustment are required for accurate keratometry.