Scleral lenses in glaucoma patients

Why there is a concern

A scleral lens rests on conjunctiva over the sclera, near the outflow pathway. The hypothesis is that landing zone pressure compresses episcleral veins or deforms tissue around Schlemm’s canal and raises outflow resistance.^[4] A 2026 review adds evidence of increased anterior chamber volume, a narrower iridocorneal angle, and Schlemm’s canal compression during wear, and notes that many studies measured too early, before maximum compression after more than 4 hours of wear.^[2]

The practical problem is measurement. With the cornea covered, standard tonometry is impossible during wear, so studies have used scleral pneumotonometry, transpalpebral, Schiotz, or peripheral rebound tonometry, or a large central fenestration, and many have studied only healthy eyes over short periods.^[1]

What the IOP studies show

After removal, on the cornea:

• A meta-analysis of 22 studies (830 eyes) found no significant IOP change after removal (mean difference 0.38 mmHg, p = 0.27), with high heterogeneity (I² = 78%).^[3]
• In 32 new wearers, Goldmann IOP after removal changed by 1 mmHg or less on average over six months.^[5]
• In 91 eyes followed for 12 months in 16.4 mm lenses, IOP fluctuations after removal stayed below 1 mmHg on average.^[6]
• In 60 Chinese participants over three months, mean IOP varied by less than 0.3 mmHg, but 10% of eyes showed a rise of 2 mmHg or more on two consecutive visits, including the last.^[7]
• In 17 keratoconus patients over three months, mean IOP rose 0.33 mmHg (not significant); temporal angle narrowing was significant in women, older age was associated with a narrower temporal angle, and the authors advise watching for temporal narrowing.^[8]

During wear, by indirect methods (healthy eyes unless stated):

• Twenty-nine adults in 15 mm lenses for 2 hours: no IOP change after removal and no change in peripheral pneumotonometry during wear.^[4]
• Fifty young adults, fenestrated lens for 1 to 2 minutes: rebound IOP rose in 96%, by 3.8 mmHg on average in those participants, and returned to near baseline after removal. The authors could not say whether the rise was real or artifact.^[9]
• Twenty-six adults over 6 hours, fellow eye as control: Icare IOP rose 2 mmHg in the lens eye; a transpalpebral tonometer showed no meaningful change and correlated poorly with Icare.^[10]
• Randomized, 15.6 mm and 18.0 mm lenses: scleral IOP rose 1.16 and 1.37 mmHg at 2.5 hours, with no difference by size and no change in corneal IOP after removal.^[11]
• Randomized crossover, 31 adults, 8 hours: transpalpebral IOP rose from 11 to 16 mmHg after application, stayed there through wear, and returned to baseline after removal. The two tonometers used agreed poorly.^[12]

The 2026 review reads this body of work as a moderate rise during wear, under 5 mmHg, unlikely to harm a healthy nerve but with possible long-term risk for patients with glaucoma or at risk of it. It concludes that it is too early to know.^[2]

Optic nerve findings

• Healthy adults over 6 hours: minimum rim width thinned in both the lens eye and the control eye, and not significantly more with the lens.^[10]
• Healthy young adults over 8 hours: small peripapillary RNFL thinning (110 to 107 µm) during wear that reversed after removal.^[12]
• Keratoconus patients after 6 hours in optimized lenses: Bruch’s membrane opening minimum rim width thinned by 10.5 µm, compared with 4.8 µm without lenses. The authors advise close optic nerve monitoring for patients at risk.^[13]

A 2023 review concludes that ongoing assessment of optic nerve structure and function is advisable in patients at risk for glaucoma who need scleral lenses.^[1]

Glaucoma is common in therapeutic fits

At one PROSE center, 24 of 281 patients fitted (8.5%) had a glaucoma diagnosis and 17 (6.0%) were glaucoma suspects; the authors describe this as higher than the general population.^[14] Many of these patients have ocular surface disease and use chronic topical medication, which matters for drop choice below.

Blebs and drainage devices

• Outcomes after bleb-forming surgery: a 15-year academic series found 20 of 39 eyes (51%) wore any contact lens successfully for at least a year, with no difference between trabeculectomy and drainage device eyes. Rigid gas permeable lenses were more common among successes; only 1 of 9 eyes in non-impression-fitted scleral lenses succeeded, while 4 of 5 eyes in impression-fitted scleral lenses did. Complications in successful wearers included one failed bleb and one case of corneal edema. The authors note that a bleb, tube, or patch graft at the limbus makes fitting harder and could raise the risk of corneal ulcer and blebitis.^[15]
• PROSE after incisional surgery: of 5 eyes with prior incisional glaucoma surgery at one center, 3 were fitted successfully.^[14]
• Design strategies: a 2025 review describes reducing lens diameter, notches, focal vaults or relief zones over the tube, toric or impression-based landing zones, and, at the surgical stage, pars plana or posterior tube placement and patch grafts that make later lens fitting easier. It lists tube compression, conjunctival thinning and erosion over the tube, and bleb erosion, leakage, or reduced filtration among the risks.^[16]

If a patient may need scleral lenses later, it is worth raising with the glaucoma surgeon before surgery, since tube position and patch graft choice affect what the fitter can do.^[16]

Drops

A review of therapeutic scleral lens practice advises using topical prescription medications before or after lens wear, waiting at least 10 minutes before applying the lens, and eliminating benzalkonium chloride-preserved medications in surface disease where alternatives exist, particularly glaucoma drops.^[17] BAK is cytotoxic to corneal and conjunctival epithelium, with effects that are more problematic with chronic use.^[18] Tell the fitter about any change in glaucoma medication; a new preservative can look like a lens problem.

A monitoring plan for patients who need both

1. Before the fit: baseline OCT of the nerve and RNFL, visual field, IOP, and gonioscopy. Send the fitter the diagnosis, target pressure, surgical history, and the location of any bleb or tube.
2. During adaptation: IOP after removal at your usual visits, plus a repeat OCT once the patient is in full-time wear.
3. Ongoing: structural and functional testing at the interval you would use for that patient’s glaucoma stage, with a lower threshold to shorten it. A stable post-removal IOP is reassuring about the eye without the lens, not about pressure during wear.^[1]
4. If progression appears: discuss with the fitter whether the landing zone can be redesigned or wear time reduced, and weigh the lens’s visual benefit against the alternatives.