Why have a patient come back for multiple soft multifocal lens trial visits and settle for subpar vision when you can go custom! Today’s lathe-cut soft multifocal lenses can be modified to suit the structural and optical needs of your patients.

It All Starts With a Well-Draped Fit

A –3.00D spherical commercial soft lens fit on an eye that has a larger-than-average horizontal visible iris diameter (HVID), as in Figure 1, may yield an adequate fit; however, for a multifocal soft lens, such a fit will likely not be tolerated by the patient. In addition to increased lens awareness with each blink, the patient is set up for functional failure, as optimal performance of many simultaneous-designed lenses is contingent on an evenly draped lens over the corneal surface. For HVIDs of 12mm or greater, a custom lens diameter of around 15.0mm will better fit the larger-than-average sagittal height of the eye.

Lining Up the Optics

Even if a lens is well-centered, the line of sight is positioned slightly up and nasal to the pupil center. Couple this with the pupil dynamics, and the optical misalignment when a lens is on eye can significantly degrade visual quality.

Rather than troubleshooting by increasing the add power, consider customizations such as adjusting pupil zone sizes or offsetting the optics (Figure 2). Offsetting center-near optics 1.0mm nasally can improve ghosting and shadows around letters and can reduce “smeared” fonts at near-viewing distances (Ramdass et al, 2018).

Aberration Control

Toric optics are often stabilized on eye using some form of prism ballast, and when customized, this is easily reproducible. Studies continue on the use of wavefront-guided technology to correct aberrations beyond the easily correctable lower-order types. The concept of using “over-aberrometry” to determine residual higher-order aberrations and to customize a soft lens to correct them is another method to theoretically manage reduced visual quality experienced by patients.

Like-for-Like Surfaces

The properties of a custom soft lens’s material can impact patient comfort during lens wear. Silicone hydrogel (SiHy) materials provide the highest amount of oxygen to the corneal surface, yet optimizing surface wetting of these materials to maintain successful lens wear remains a challenge. Solution considerations, moisturizing drops, and possible lens-surface treatments can help mitigate the inherent hydrophobic tendencies of SiHy custom soft lenses. CLS

For references, please visit www.clspectrum.com/references and click on document #305.