Are Hybrid or Scleral Contacts Better?
June 23, 2024
Are hybrid or scleral contact lenses better? The answer depends on several factors unique to you. For most with keratoconus that need rigid surface contact lenses for functional vision, scleral lenses are a godsend. Yet there is a contingent for which hybrid lenses are more appropriate. Because contact lenses are Class II medical devices, hybrid and scleral contact lenses are prescribed by an eye care professional. This is why your trusted contact lens prescriber is usually best to advise what will bring you a desirable outcome. That said, you can gain some appreciation on why many patients do well with scleral contact lenses and some do best with hybrid lenses, by reading on.
A Short History of Hybrid Lenses
Hybrid contact lenses were commercialized in the late 1970s, with the intention of providing soft lens comfort with the vision quality of a rigid lens. These early hybrid lenses were plagued by problems such as the rigid and soft junction of these lenses separating and causing eye irritation. Also, abnormal blood vessel growth into the clear cornea of the eye due to the body’s attempt to make up for the low oxygen transmissibility of these lenses. In the 2000’s, a new generation of hybrid contact lenses, under the tradename SynergEyes, received FDA approval. SynergEyes sought to improve upon the previous hybrid lens shortcomings.
SynergEyes hybrid lenses have provided many benefits for keratoconus patients. The longstanding staple for vision correction for keratoconus patients were small diameter rigid gas permeable lenses. Unfortunately, these legacy lenses are more prone to dislodging or ejecting and getting dust underneath the lens leading to bouts of eye discomfort. Hybrid lenses are immune to these same issues. Even so, over the past few years, many hybrid lens wearers have done even better with scleral contact lenses. In effect hybrid lens wear is a steppingstone from moving from rigid gas permeable to modern scleral contact lenses.
Scleral Lens Advantages
While there are exceptions, appropriately prescribed scleral lenses frequently provide better comfort and vision than hybrid lenses, along with more stable vision upon removal.
Hybrid lenses are designed to touch the cornea, the clear, sensitive dome of the eye. By comparison, scleral lenses are prescribed to avoid touching the cornea by resting on the insensitive white part of the eye or sclera. This is why well-prescribed scleral lenses are typically more comfortable than optimally prescribed hybrid lenses. Scleral lenses also trap moisturizing non-preserved saline against the sensitive cornea.
Scleral lenses enable a higher level of vision correction than hybrid lenses because they are available to correct residual astigmatism, a common visual aberration that otherwise degrades vision. The correction of residual astigmatism requires a contact lens that remains stable on the eye without spinning around. Hybrid lenses are not rotationally stabilized, meaning that they can rotate on the eye and are not available to correct residual astigmatism. Modern scleral contact lenses are rotationally stabilized because they pattern the white part of the eye which is rarely round. This allows for scleral lenses to correct rotationally sensitive aberrations of the eye.
Since hybrid lenses can temporarily mold the cornea, vision can change after they are removed. By comparison, scleral lenses are designed not to touch the cornea, so the curvature of the eye does not drift upon their removal. This means that for patients that wear eyeglasses after removing hybrid lenses, their vision can dramatically drift in the ensuing hours.
Scleral lenses are also more durable and are intended to be replaced annually, although in some cases they can last much longer. Hybrid lenses by comparison are 6-month replacement lenses according to their FDA approval, and indeed they have a shorter longevity before deposits from protein, lipid, and minerals soil the lens surface regardless of lens care.
Who Still Wears Hybrid Lenses?
Over the past decade, many keratoconus patients that formerly wore hybrid contact lenses have successfully moved into wearing scleral lenses. This trend reflects the success of well-prescribed scleral lenses. Still, some patients do best in hybrid lenses for a small number of reasons.
Some hybrid lens wearers that have also worn scleral lenses find greater ease and familiarity applying hybrid lenses. Hybrid lenses are 14.5 mm in diameter, whereas scleral lenses are usually about 10% larger in diameter. Those with unusual trouble keeping their eyes open may find hybrid lenses easier for handling. Scleral lenses also require proper application to trap non-preserved saline fluid against the eye without air bubbles. Hybrid lenses may be less prone to air bubble entrapment, which can impact vision and cause eye discomfort. There are also some patients that remain in hybrid lenses because they like familiarity and are reluctant to change even if scleral lenses would offer them an improved outcome.
ReVision Optometry is a referral-based practice in San Diego providing contact lens services for patients with keratoconus. To schedule an appointment, request your appointment online, or call our office at 619.299.6064.