NCLE 3.3

Two broad categories of rigid contact lenses would include the Palpebral Lens and the larger Lid Attachment Lens.

.

THE PALBEBRAL LENS:

General characteristics: The lenses are small and thin.

They are small enough to be contained within the

cornea with little or no contact with the upper or lower

lids. Diameters usually range from 7.8 to 8.6 mm. With

each blink the lens moves up and approaches the

superior limbus. Between blinks, in ideal cases, it falls

slowly toward the inferior limbus lowering to just

below the center. Thicknesses are generally in the range

of 0.08 and 0.12 mm. and the peripheral curves are

relatively steep.

The lenses should be large enough to provide a minimal

sense of motion during blinking producing as little

glare as possible. However, too large a lens can result

in reduced comfort. The thinness of the lens results in

some flexure with each blink which creates a tear pump

that can help with tear exchange.

• It provides excellent tear exchange resulting in minimal corneal edema and spectacle blur.

2. Eye movement is free from lid irritation since the lens is smaller than the palpebral fissure.

3. The thinner lenses are more comfortable than conventional lenses and can therefore be employed as a possible alternative to soft lenses especially when a significant amount of corneal astigmatism is present.

4. A high riding rigid lens problem may be solved through the use of the small microthin lenses which may center better.

5. Patients who have induced corneal astigmatism caused by the the "molding" effect of larger lenses may benefit from a smaller microthin lens.