What scleral lenses can fix, and what they can’t
Scleral lenses work on the front surface of the eye. The saline fills in the bumps, scars, and irregular shape of the cornea, and the smooth front of the lens gives light a clean surface to pass through. For blur that comes from an irregular cornea, that can make a large difference.
They can’t improve vision that’s been lost somewhere else. Conditions that affect the retina, like macular degeneration or diabetic retinopathy, the optic nerve, or the brain’s visual pathways won’t respond to a scleral lens, because the problem isn’t on the front of the eye. The same goes for clouding inside the eye, such as a cataract, or a scar that clouds the cornea itself rather than just making its surface uneven.
Many people have more than one thing going on. If your vision isn’t as sharp as you hoped, ask your eye doctor how much of the blur is coming from the surface, which the lens can address, and how much from elsewhere.
What the research shows
In a review of 157 eyes with keratoconus that had worn scleral lenses successfully for at least a year, average best-corrected vision improved from 0.50 logMAR with glasses to 0.08 logMAR with scleral lenses.[1] On that scale, lower numbers mean sharper vision and 0.0 equals 20/20. Those averages work out to roughly 20/63 with glasses and roughly 20/24 with scleral lenses.
That’s a big average improvement, but averages hide a lot. Some eyes do better and some don’t reach that level. The study also included only people who were still wearing their lenses after a year.
Vision problems can also come and go. In a study of 120 veterans, 15.8% had mid-day fogging or bubbles.[2] In the keratoconus study, reservoir fogging was recorded in 7.0% of eyes and deposits on the lens in 8.9%.[1] And in a study of one practitioner’s first 156 fittings, poor vision was behind 23.6% of the lens reorders for people with irregular corneas.[3] Getting vision right sometimes takes more than one lens.
Common problems, and what can help
Blurry right after insertion. Usually a bubble or debris. Remove, refill to the brim, reinsert, and do the three checks. See blurry right after insertion.
Cloudy or foggy by midday. This can start in front of the lens, where an uneven tear film over the lens scatters light, often linked to dry eye or oily glands along the lid margin not working well. Or it can start behind the lens, where debris builds up in the fluid reservoir during the day until vision turns milky. Your fitter can tell which. Options include changing how the lens seals, a planned midday removal and refill, a coating that helps the lens surface stay wet, and treating the underlying dry eye.
Vision that’s sharp in the morning and softer later. If cleaning the lens doesn’t fix it, the prescription itself may be shifting as the lens settles, or the cornea may be swelling. Your fitter can recheck your prescription after the lens has settled and look for swelling when the lens comes out. Report this one rather than living with it.
Glare, halos, or ghosting. Starbursts around headlights or a faint double image can mean the lens sits slightly off-center. Fitters can adjust the design to center it better, use a larger optical zone, or in some cases use more advanced optics.
A lens that’s lost its sparkle. Over weeks, a lens can develop a film that cleaning doesn’t remove, or pick up scratches. Your fitter may adjust your cleaning routine or replace the lens.
A prescription that’s changed. Eyes change over time, and some conditions progress. Keep your follow-up visits even when things seem fine.
When blurred vision is urgent
Most vision problems with scleral lenses are frustrating rather than dangerous. But vision that gets worse and doesn’t clear when the lens is out, especially with pain, redness, or light sensitivity, is a reason to remove the lens and call your eye doctor the same day.
Setting realistic expectations
Before and during your fitting, ask your fitter:
- How much improvement can I realistically expect, given everything going on with my eyes?
- Is anything besides my cornea limiting my vision?
- What will we try if my vision isn’t where we want it?
Scleral lenses can make a large difference for many people, but they aren’t a guarantee of perfect vision. A fitter who sets clear expectations up front is easier to work with when something needs adjusting. If you’ve tried several changes and you’re still not satisfied, see what if scleral lenses don’t work for me?
Common questions
Why is my vision blurry right after I put the lens in?
The most common cause is an air bubble under the lens or something on it. Take the lens out, refill it to the brim with fresh saline, and reinsert. If your vision is still blurry with a clean, bubble-free lens, tell your fitter.
Why does my vision get cloudy in the afternoon?
This is often called midday fogging. It can come from film building up on the front of the lens or debris building up in the fluid behind it. Your fitter can work out which, and options include changing the fit, a planned midday removal and refill, or treating dry eye.
Will I see 20/20 with scleral lenses?
Some people do and some don't. It depends on what's causing your blur. If part of your vision loss comes from somewhere other than the front of the eye, a lens can't correct that part. Ask your fitter what's realistic for your eyes.
Do I still need glasses with scleral lenses?
Many people keep a pair for when lenses are out, and some need reading glasses over their lenses for close work. Ask your fitter whether your lenses can be designed to reduce that need.