Consultant's Corner
Low Riding Lenses: What to Do Next
By Michael A. Johnson, FCLSA
Director of Consultation Services
One of the most frustrating fitting problems practitioners have to overcome is the low riding lens syndrome. Art Optical’s consultation department fields a considerable number of calls each day concerning low riding lenses and we have developed some helpful techniques to improve this fitting problem.
The first step is to observe the fit of the lens after having the patient blink three or four times in rapid succession. Does the lens move freely with the blink and then drop inferior, or does the lens remain in the inferior position with little or no movement? Lenses that move freely with the blink and then settle back down in an inferior position are typically on the loose side and may need to be steepened slightly or increased in diameter to make them come up to a central or central superior position. I like to include a lenticular design with a slight minus carrier effect to encourage better superior lid attraction. I will also attempt to decrease the center thickness if possible (but be aware that making a lens too thin for high corneal astigmats could cause lens flexure) which helps to reduce the overall mass of the lens. If the lens does not appear to be flat and does not move freely from the inferior position on a full blink then we will typically assume that the base curve fit is too steep and or the diameter to optical zone relationship is out of proportion. If this situation is present, I will usually recommend that the base curve be flattened slightly and that the optical zone diameter be reduced by .3 to .4mm to open the mid-periphery of the lens design. I will again include a minus carrier lenticular design and decrease the center thickness, if possible, just to make sure that I am accounting for every possible way to make the new lens center properly.
Low riding lenses are a common problem with GP’s but one that can typically be resolved by following these suggestions. If this still is not resolving the centration problem, we would be happy to discuss further alternative modifications and designs that could be successful.
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