Scleral Lenses vs. Hard, Soft and Hybrid Contacts for an Irregular Cornea
When a cornea is irregular, from keratoconus, ectasia after LASIK, a scar or a transplant, ordinary contacts usually are not enough. But “specialty lens” covers several very different designs, and patients often come in having been told about only one of them.
Here is how the main options compare, and how I decide which one to try first.
The Problem Every Option Is Trying to Solve
An irregular cornea bends light unevenly. Glasses can only correct regular, predictable astigmatism, so they leave the distortion behind. To see clearly, the eye needs a smooth surface in front of the cornea.
Every lens below is a different way of providing that surface. They differ in how they do it, how comfortable they are, and how much irregularity they can handle.
Soft and Custom Soft Lenses
A soft lens is flexible. It drapes over the cornea and takes on its shape.
Strengths: Comfortable from day one, familiar to anyone who has worn contacts, easy to handle.
Limits: Because the lens copies the cornea’s shape, it copies the irregularity too. Thicker custom soft lenses for keratoconus can mask a little of it, which makes them useful in early or mild disease. As the cornea gets more irregular, soft lenses stop giving sharp vision.
Who it suits: Early keratoconus, mild irregularity, and people who need comfort above all and still see acceptably.
Corneal Rigid Gas Permeable (RGP) Lenses
These are the small “hard” lenses, usually a bit smaller than the colored part of the eye. They hold their shape, and the tears that fill the gap behind them smooth out the irregular surface.
Strengths: Excellent optics, decades of track record, relatively affordable, and still the most commonly prescribed lens for keratoconus. At one academic eye center, about 60 percent of keratoconus patients wore corneal RGPs in 2020 (Contact lens prescribing trends for keratoconus, 2022).
Limits: They rest on the cornea, often right on the tip of the cone. Some people never get comfortable with that, and on a steep or off-center cone the lens can slide around or pop out. Dust getting under the lens is a common complaint.
Who it suits: People who tolerate them well, have a fairly central cone, and want a proven, lower-cost option.
Hybrid Lenses
A hybrid has a rigid center and a soft outer skirt. The rigid center provides the smooth optical surface. The soft skirt holds it in place and adds comfort.
Strengths: Rigid-lens optics with something closer to soft-lens comfort. Good centration.
Limits: Fitting is particular, the lenses can be harder to insert and remove than either a soft or small hard lens, and they are not a good match for every cornea shape.
Who it suits: People who see well in a rigid lens but cannot tolerate one, and whose cornea shape suits the design.
Piggyback Lenses
Piggybacking means wearing a small RGP lens on top of a soft lens. The soft lens acts as a cushion.
It can be a useful bridge for someone who needs RGP optics but cannot get comfortable, though managing two lenses per eye is more work, and many patients who would once have piggybacked are now fitted in a scleral instead (Contact lens in keratoconus, Indian Journal of Ophthalmology).
Scleral Lenses
A scleral lens is a large rigid lens that vaults completely over the cornea and rests on the white of the eye. It is filled with preservative-free saline before it goes on, so the cornea sits under a layer of fluid all day.
Strengths:
- Handles the most irregular corneas, including advanced keratoconus and scarring
- Nothing touches the cornea, so there is no rubbing on the cone
- Very stable, because the large lens is hard to dislodge
- The fluid layer helps eyes that are also dry or irritated
In a large worldwide survey, scleral lens wearers with keratoconus reported higher satisfaction with both vision and comfort than corneal RGP wearers (SCOPE study group, cited in the 2022 prescribing trends paper).
Limits:
- Insertion and removal take practice, usually with a small suction tool called a plunger
- The lens must be filled with sterile saline every time it goes on
- Some wearers get “midday fogging,” a haze that builds up in the fluid and needs a quick remove-and-refill
- The fitting is more involved and usually costs more than smaller lenses
Who it suits: Moderate to advanced keratoconus, corneas that cannot hold a smaller lens, people who failed other lenses for comfort, and people with both an irregular cornea and a dry ocular surface.
A Quick Side-by-Side
Swipe the table sideways to see all four lenses.
| Soft / custom soft | Corneal RGP | Hybrid | Scleral | |
|---|---|---|---|---|
| Rests on | Cornea | Cornea | Cornea, soft skirt on edge | White of the eye |
| Irregularity it can handle | Mild | Mild to advanced | Mild to moderate | Mild to severe |
| Comfort | High | Varies, often hard to adapt | Good | High once adapted |
| Handling | Easy | Easy | Moderate | Takes practice |
| Fit complexity | Low to moderate | Moderate | Moderate to high | High |
How I Choose Which Lens to Try
I do not start from a favorite lens. I start from the eye and the person.
How irregular is the cornea, and where is the cone? How well does the eye see in each design during a trial? Are the eyes dry? Has this person tried and given up on a lens before, and why? What do they need to do: drive at night, read a computer screen for eight hours, work outside in dust?
Sometimes the answer is a small RGP, and that is a fine outcome. Often, especially with moderate or advanced keratoconus or a history of failed lenses, it ends up being a scleral. If you want the deeper story on that lens, read scleral lenses for keratoconus.
Getting Evaluated
We fit specialty lenses, including scleral lenses, at our offices in Pasco, Sunnyside and Hermiston. If you live in Kennewick, Richland or West Richland, the Pasco office on Road 68 is the closest, about 13 to 18 minutes away. In Eastern Oregon, see our Hermiston scleral lens page.
Call the office you plan to visit and ask for a scleral or specialty lens evaluation: Pasco (509) 543-7953, Sunnyside (509) 839-4575, Hermiston (541) 567-5283.
This article is general information, not medical advice. The right lens for your eyes is decided at an examination.