Why dryness happens with a lens full of saline
A scleral lens vaults over your cornea and holds a layer of saline against it all day. That’s why scleral lenses are used for some severe dry eye conditions. But the lens doesn’t replace your tears everywhere:
- The front of the lens needs your tears to spread over it smoothly, the same way your cornea does. If they don’t, the surface dries in patches and vision looks smeary.
- Your eyelids glide over the lens every time you blink, and the oil glands along their margins (meibomian glands) supply the oily part of your tears.
- The white of the eye beyond the lens edge is still exposed.
Poor front-surface wetting
When tears bead up or break apart on the front of the lens instead of forming a smooth layer, light scatters and vision gets hazy. In a study of 48 habitual scleral lens wearers, those who reported fogging were more likely to have poor front-surface wetting seen at the slit lamp, while their lens fits were no different from those without fogging.[1]
What helps:
- Cleaning. Film and oils make wetting worse. Rub both sides of the lens with your cleaner every night, and keep lotions and oily products off your hands. The FDA advises putting makeup on after lenses are in.[7] See film and deposits on the lens.
- A surface coating. In a small double-masked crossover trial, 21 scleral lens wearers with dry eye wore coated and uncoated versions of the same lens for 30 days each. The coated lens gave better comfort, fewer dry eye symptoms, less frequent foggy vision, and longer comfortable wearing time.[4] Ask your fitter how long a coating is expected to last and whether it changes how you clean the lens.
Your eyelids matter
Eyelid problems are common in scleral lens wearers. In a study of 49 habitual wearers, eyelid disease was common whatever the reason for lens wear. Among eyes being treated for ocular surface disease, 39% (7 of 18) had no expressible oil from their meibomian glands, compared with 11% (3 of 27) of eyes with an irregular cornea.[2]
Dry eye and lens problems tend to travel together. In a survey of people with dry eye disease, 75% (50 of 67) of scleral lens wearers who answered reported midday fogging or clouding of vision.[3] In a study of 48 wearers, those with fogging had dry eye symptom scores in the severe range.[5]
If your eyelids or tear film are part of the picture, treating them may help your lenses work better. Your fitter may treat this themselves or refer you to a dry eye specialist.
Drops and products
- Ask before you add anything. The FDA advises asking your eye care professional before using any medicine or eye product, even over-the-counter ones.[7]
- Watch for preservatives. Preservatives such as benzalkonium chloride, common in multi-use eye products, can damage cells on the surface of the cornea and conjunctiva.[6] This matters most for anything that goes inside the lens, which must always be sterile, preservative-free saline.
- Keep the case and tools clean. Dryness that comes with redness or discharge may not be dryness at all.
Questions to ask your fitter
- Is my lens surface wetting well? Would a coating help?
- Do my meibomian glands or eyelids need treatment?
- Which rewetting drops are safe with my lenses, and how often?
- Would buffered saline or a different cleaner make a difference for me?
- Should I plan a midday removal and refill on long days?
Common mistakes
- Using drops with preservatives over your lenses without asking your fitter.
- Filling the lens with anything other than sterile, preservative-free saline.
- Treating the lens but not the dry eye underneath it.
- Assuming dryness means scleral lenses can't work for you, before your fitter has tried the fixes.
Common questions
If scleral lenses are used to treat dry eye, why do my eyes still feel dry?
The lens keeps saline against your cornea, but the front of the lens, your eyelids, and the white of the eye beyond the lens edge still rely on your own tears. If your tear film or eyelid glands aren't working well, you can still feel dry and see smeary.
What's a lens coating, and can I get one?
Some scleral lenses can be given a surface treatment that helps tears spread across the front. In a small double-masked trial in wearers with dry eye, coated lenses were more comfortable than uncoated ones. Ask your fitter whether it suits your lens.
Can I use any eye drops with scleral lenses in?
Ask your fitter first. The FDA advises checking with your eye care professional before using any eye product, even over-the-counter ones. Preservatives in some drops can irritate the eye's surface.
Does the filling saline matter for dryness?
It needs to be sterile and preservative-free. Some people find buffered saline more comfortable. Ask your fitter before switching.
