Contacts for keratoconus
New options may better meet diverse patient needs.
Rigid gas-permeable (RGP) designs remain the most popular contact lenses for moderate keratoconus patients. However, newer designs may offer better comfort and reduced complication risk, Kathryn A Colby MD, PhD, told the 10th EuCornea Congress in Paris, France. She recommended collaborating with contact lens experts, educating patients that fitting takes time and patience and keeping up with new technologies to better meet individual patient needs.
Toric soft lenses are the most comfortable option, but are only suitable for mild cases, said Dr Colby, who is Professor and chair of ophthalmology and visual science at the University of Chicago, USA. For moderate cases, RGPs are currently the first line of treatment.
In the past, RGP lenses were fitted “flat”, bearing on the apex of the cone. This was comfortable for patients, but increased corneal complications, including swelling, staining and scarring, Dr Colby said. Today’s “three-point touch” approach has minimal apical contact, a low vault and minimal peripheral touch. It provides stable vision and allows tear exchange with minimal chronic damage to the corneal epithelium.
Rose K is the most common RGP lens, Dr Colby noted. It is customisable, well-tolerated, widely available and relatively inexpensive. The K2 version features an aspheric design to reduce spherical aberrations, a larger optical zone to reduce glare and haloes in low light and a steepened inferior quadrant for a more stable fit. The K2 XL is a larger diameter “semi-scleral” design that can be used in post-graft eyes, with a customisable edge lift to protect the ocular surface.
Less common are piggyback lenses, which mount an RGP on a soft base. This can increase comfort and makes the design suitable for use with inferior or marginal cones, Dr Colby said. However, it also means patients must care for two types of lens.
“We have a hard enough time getting them to take care of one type of contact lens,” she commented.
Hybrid lenses are similar to piggyback lenses, but in a single piece, though these can be slippery, making them difficult to handle, Dr Colby said. Scleral lenses vault higher, improving comfort, but require saline to insert. The PROSE lens is customisable to accommodate cones, but is expensive and not available everywhere.
“Ever-expanding contact lens options are available and most patients can be fit successfully,” Dr Colby said. However, patients should be counselled that achieving a good fit often requires several tries. Patience and help from a contact lens specialist are very useful, she added.
Kathryn Colby: firstname.lastname@example.org