What would be the most appropriate lens change if a rigid lens shows centrally minimal lens movement and poor tear exchange?

When a rigid contact lens exhibits minimal lens movement centrally and poor tear exchange, it indicates that the lens may be fitting too tightly on the cornea. A tight fitting can hinder the natural flow of tears under the lens, leading to discomfort and potentially compromising corneal health.

Reducing the diameter of the lens would effectively lessen the relationship of the lens with the corneal surface. This change allows for more movement of the lens during blinks, which can facilitate a better tear exchange beneath the lens. Improved tear exchange can enhance comfort and help maintain corneal health by ensuring adequate hydration and nutrient delivery to the cornea.

In contrast, increasing the diameter would likely exacerbate the tightness if the lens is already fitted closely. Steeping the base curve might maintain or worsen the tight fit, rather than alleviating it. Increasing the optical zone diameter also does not directly address the issue of fit and may not provide the necessary movement for proper tear exchange. Thus, reducing the diameter is the preferred approach to enhance lens movement and tear exchange.