What the research says about eye pressure
A scleral lens rests on the white of the eye, close to the channels that drain fluid out of it. That has led researchers to ask whether the lens could press on those channels and raise eye pressure, which is the main treatable risk factor in glaucoma.
After the lens comes out, pressure looks unchanged on average. A 2026 review pooled 22 studies covering 830 eyes. Eye pressure measured after lens removal showed no significant change, with an average difference of 0.38 mmHg.[1] The authors point out that pressure wasn’t measured while the lens was on the eye, so short-lived rises during wear can’t be ruled out, and they advise monitoring in higher-risk groups, including people with glaucoma.[1]
Averages can hide individuals. In a study of 60 people followed for three months, average pressure varied by less than 0.3 mmHg. But 10% of eyes showed a rise of 2 mmHg or more at two visits in a row, including the last one.[2]
During wear, the picture is less settled. A 2026 review by a scleral lens researcher argues that the evidence points to a moderate rise in pressure, under 5 mmHg, while the lens is worn. He considers it unlikely to matter for a healthy optic nerve, but says people with glaucoma, or at risk of it, could be affected over the long term, and that it’s too early to know for sure.[3]
People with glaucoma have barely been studied. A 2025 review notes that no studies had assessed pressure changes with scleral lens wear in people with glaucoma or high eye pressure. Its authors suggest not fitting scleral lenses just to replace glasses in these patients. When a scleral lens is needed for an irregular cornea or severe surface disease, they suggest a larger lens (18.0 mm or more), which lands further from the drainage area.[4]
What this means in practice: glaucoma is a reason for more care, not an automatic no. Make sure your fitter knows about your glaucoma and your glaucoma doctor knows about the lens. Ask how often your pressure and optic nerve will be checked once you start. For more on the pressure research, see can scleral lenses raise eye pressure?
Glaucoma drops and scleral lenses
Benzalkonium chloride (BAK), a preservative used in about 70% of eye drop formulations, can damage the cells on the eye’s surface. The harm is more of a problem with long-term use, as in lifelong glaucoma treatment.[5] Under a scleral lens, the fluid in the bowl sits against your cornea for hours. Preservatives in medicines, and glaucoma medicines specifically, are listed among the causes of toxic damage to the cornea in scleral lens wearers.[4]
So:
- Fill the lens only with the preservative-free solution your fitter prescribes. See saline and solutions.
- Ask both doctors when to use your drops in relation to inserting and removing the lens. See using eye drops with scleral lenses.
- Ask whether a preservative-free version of your medicine is an option.
- Don’t change or skip glaucoma drops to make lens wear easier. That decision belongs to your glaucoma doctor.
After glaucoma surgery: blebs and tubes
Trabeculectomy creates a small blister of drained fluid (a bleb) under the conjunctiva. A tube shunt places a small drainage device. Both usually sit near the edge of the cornea, right where a scleral lens lands.
Pressing on a bleb can cause erosion, leaks, reduced drainage, and higher pressure. A lens pressing on a tube can block it or wear away the tissue covering it. Neither is an absolute bar to wearing a lens, though. Fitters use notches, raised zones over the bleb or tube, smaller diameters, and impression-based custom designs to avoid contact.[4]
The best data come from one academic center. Of 39 eyes in 32 people who were fitted with contact lenses after bleb-forming surgery, 20 (51%) were still wearing them successfully a year later. Among those 20 eyes, 5 had complications, mostly on the corneal surface. Rigid gas permeable lenses were more common among the successes, and scleral lenses that weren’t impression-fitted were more common among the failures.[6] It was a small study that mixed several lens types, so it can’t say how any one person will do.
Infection around a bleb is a concern with any contact lens, which makes careful hygiene especially important.[4] The safety page covers the habits that matter most.
Common questions
Can a scleral lens treat glaucoma?
No. Glaucoma is a disease of the optic nerve, and a scleral lens only changes the front surface of the eye. If you have glaucoma and also need a scleral lens for an irregular cornea or a severe ocular surface problem, the two are managed side by side, and your glaucoma treatment continues as your doctor directs.
Should I put my glaucoma drops into the lens before I insert it?
No, not unless your doctor specifically tells you to. The bowl of a scleral lens should be filled only with the sterile, preservative-free solution your fitter prescribes. Many glaucoma drops contain preservatives, and preserved medicines are a known cause of surface damage under scleral lenses. Ask both of your doctors how to time your drops around putting the lens in and taking it out.
Can my eye pressure be checked while I'm wearing the lens?
Measuring pressure with a scleral lens in place is difficult, and most studies measure it after the lens is removed. Ask your glaucoma doctor and your fitter how they plan to monitor your pressure and optic nerve once you start wearing the lens, and make sure each knows what the other is doing.
I've had a trabeculectomy. Is a scleral lens off the table?
Not necessarily. A filtering bleb is not an absolute bar to wearing a lens, but the lens must not press on it. Fitters can add a notch or a raised zone so the lens clears the bleb. In one study of eyes after bleb-forming surgery, about half were still wearing a contact lens a year later. Your glaucoma surgeon should be part of the decision.