Four routes to the same kind of lens
All of these make a scleral lens: a rigid gas permeable dome that holds saline over your cornea and rests on the white of the eye. What differs is how the shape is worked out.
| Route | How the lens is designed | Often considered for | Things to know |
|---|---|---|---|
| Standard (trial-lens) fitting | The fitter places lenses from a diagnostic set, judges the fit, and orders changes | Most people | Can take several lenses; depends heavily on the fitter’s skill |
| Scan-based | An imaging scan maps the cornea and white of the eye, and software helps design the lens | Uneven scleral shapes; fewer trial lenses | Needs the equipment; scans have limits. See scleral profilometry |
| Impression-based | A mold of the front of the eye is scanned and the lens is cut to match it | Very irregular eyes, bumps on the white of the eye, failed standard fits | Longer lab times reported; cost and coverage vary. See impression-based lenses |
| PROSE | A customized lens with proprietary design software, within a structured treatment program | Severe surface disease and difficult cases | Offered at specific clinics. See what is PROSE treatment? |
A 2025 review describes how customized landing zones, scan-based fitting, and impression-based design can achieve a fit in difficult eyes, including after corneal transplants and with corneal scarring. It also notes these approaches need resources that not every practice has.[1] The newer options aren’t yet routine: in an international survey of fitters, most lenses had simple spherical landing zones, and the authors concluded advanced landing zones and optics hadn’t been widely adopted.[2]
Some routes can be combined
These aren’t always separate camps. Many fitters use scans alongside trial lenses. Some trial-lens designs offer highly customized landing zones. Some impression-based and scan-based lenses can add optics that correct higher-order aberrations. Ask your fitter what their approach actually involves rather than going by the label. See what are wavefront-guided scleral lenses?
After failed fits: what to consider
Before switching methods, find out why the previous lenses didn’t work. That answer often decides the next step.
- The lens pressed or lifted in one area. A shaped landing zone, a scan-based design, or an impression-based lens may match your eye better. See what is a toric landing zone?
- There’s a bump on the white of the eye (such as a pinguecula, a surgical bleb, or scarring). Designs that clear or match it, including notches, channels or impression-based lenses, may help.
- Vision never got sharp. Ask about optics, including correction for higher-order aberrations, before assuming it’s the fit.
- Fog, burning, or dryness persisted. These often come from the eye surface, the lids, or solutions. A new design may not solve them. See my fitter says the fit is perfect.
- Many lenses, little progress. That may be about the fitter’s experience with eyes like yours. A specialist who fits many complex eyes, whatever method they use, may be the bigger change. See finding a scleral lens specialist.
What wearers say
Wearers have strong opinions here, and they don’t agree. Some describe an impression-based lens fitting well from the start after years of failed standard fits, especially with very irregular eyes. Some found PROSE was what finally worked after other approaches failed, and valued the intensive training and same-site lens making. Others had the reverse: a standard design from a skilled fitter succeeded where a molded lens or PROSE didn’t.
The most repeated advice is to choose the fitter, not the method. Wearers also flag practical points: switching methods may mean new fitting fees and a new insurance question, impression-based lenses can have long lab waits, and traveling to a specialty center takes planning. Several wearers say their eye doctors told them not every patient needs a highly customized lens, and that a careful fit with a standard design is usually the first step.
What to ask your fitter
- “Why do you think my previous lenses didn’t work?”
- “Which methods do you use, and which would you choose for my eye, and why?”
- “Would a scan or an impression add anything for me?”
- “If you can’t get a good fit, who would you refer me to?”
- “What would switching mean for fees, coverage, and my current remake window?”
When it’s not normal
Whatever kind of lens you wear, some symptoms need same-day attention.
Common questions
Is the impression for a molded lens painful?
Wearers generally describe it as uncomfortable rather than painful. Numbing drops are used, and the eye can feel sore afterward. Those whose eyes were inflamed at the time found it harder.
Does insurance cover impression-based lenses or PROSE?
Sometimes. Coverage depends on your plan, your diagnosis, and how the practice bills, and wearers report very different results. Ask the practice to check before you start, and see our insurance pages for how medical necessity and prior authorization work.
Do I have to travel for PROSE?
PROSE is offered at its main center and at partner clinics. Wearers describe the main center making lenses on site, which shortens the fitting, while partner clinics may wait for lenses to be shipped. Ask the program which clinic is nearest and how fitting is scheduled there.
If a scan-based lens didn't work, will an impression-based one?
Possibly, but not necessarily. Ask your fitter what limited the scan-based lens: the scan, the design, or something unrelated to fit such as dry eye or solutions. That answer points to the next step.