What should be checked to ensure the fit of a contact lens on a patient's eye?

To ensure the fit of a contact lens on a patient's eye, assessing the lens movement and centration is essential. A proper fit is indicated when the lens moves slightly with blinking but remains centered on the cornea during static gazes. This movement allows for tear exchange underneath the lens, which is crucial for maintaining corneal health and comfort. If the lens is too tight, it may restrict the natural tear flow, leading to discomfort and potential complications. Conversely, if the lens is too loose, it can cause irritation and reduced visual acuity due to poor lens positioning.

Checking lens color, thickness, or brand does not directly impact how well the lens fits the patient's eye. While these factors may play a role in patient comfort or aesthetic preference, they do not provide the same critical insights into whether the lens is appropriately aligned and stable on the eye. The primary concerns when fitting contact lenses are their alignment and behavior on the eye, making movement and centration the most important aspects to evaluate.