Soft Contacts for Keratoconus: Fantasy or Possibility?
December 27, 2023
Most keratoconus patients have custom rigid surface contact lenses as their lifeline to navigate the world. For mild corneal distortion, glasses and soft disposable contact lenses sometimes will afford adequate vision. Yet in most cases of keratoconus with more corneal distortion, rigid surface lenses — including scleral contact lenses— are the mainstay to rehabilitate vision. Most keratoconus patients find that properly prescribed scleral lenses provide excellent vision and comfort. Somewhere between mild and advanced distortion, custom soft contact lenses may have a role, particularly if reduced vision is acceptable.
Abnormally Thick Soft Lenses
Over the past few decades, almost a dozen proprietary custom soft contact lens designs have entered the marketplace, attempting to allow prescribers to expand the role of soft lenses to more keratoconus patients. These lens designs share the common strategy of unusual thickness to behave more like a rigid contact lens. All these lenses have a thickness of greater than 0.40mm. That is over 5 times thicker than common disposable contact lenses!
Generally, these thick custom soft lenses fail to deliver optimal vision for anything more than mild cases of keratoconus. This is because these soft lens designs cannot replicate the smooth rigid contact surface when draped over a distorted eye. For most with keratoconus, soft contact lenses do not provide acceptable vision, even after optimized through various iterations.
Interestingly, all the soft lens designs with a thickness of more than 0.40 mm do not meet the theoretical “Holden-Mertz” minimum oxygen transmissibility to avoid swelling of the corneal tissue, even with today’s most breathable soft contact lens materials. Even so, these lens designs appear to move enough on the eye allowing sufficient oxygenation through tear exchange under the lens.
Soft Keratoconus Lens Designs
An early soft contact lens design is Flexens Tri-curve keratoconus (X-Cel Contacts). Subsequent attempts include the 2011 introduction of Alden Optical’s NovaKone, since acquired by Bausch Specialty Vision Products. In 2012 B+L announced a global licensing agreement with UltraVision CLPL for KeraSoft IC with much industry fanfare, only to fade away as the outcomes were not notably different from prior incarnations. A smattering of other soft lenses intended for keratoconus have also come and mostly gone.
Today, custom soft contact lenses have established a limited role for certain keratoconus patients. Arguably the most useful lens design for carefully selected patients is NovaKone (Bausch Specialty Vision Products), which is a thick lens design where the prescribing doctor can specify the central thickness according to the severity of the corneal distortion. This lens potentially helps the minority of keratoconus patients that do not obtain desirable outcomes even with properly prescribed scleral contact lenses.
The most promising soft keratoconus lens may be yet to come. Presently, there is an effort using a novel, ultra oxygen permeable soft lens material to address the complex aberrations found in keratoconus. ReVision Optometry has access to this lens for investigational purposes. Just don’t hold your breath on it anytime soon, as there’s no assurance it will come to market.
Will Soft Lenses Work for My Keratoconus?
If you get decent vision with eyeglasses but have not had success with properly prescribed rigid surface contact lenses including EyePrintPRO impression-based scleral lenses, custom soft contact lenses may have a role for you. In general, the majority with keratoconus will not get sufficient vision with these soft contact lenses unlike with rigid surface lenses. Special soft lenses have a role if they are easier for the wearer to handle and/or tolerate, at the expense of the utmost visual clarity.
Ultimately, if your current vision correction does not provide a desirable outcome, you need to schedule an evaluation with a contact lens prescriber that regularly manages keratoconus with custom rigid surface contact lenses, hybrid lenses, and custom soft lens designs like NovaKone. An experienced practitioner can direct you to the best treatment for your individual situation.
ReVision Optometry is a referral-based practice in San Diego providing contact lens services for patients with keratoconus and other complex eye conditions. Dr. Chou provided clinical feedback to refine the NovaKone lens design prior to commercial launch. To schedule an appointment, request your examination online or call our office at 619.299.6064.