What scleral lenses are being used for
The best snapshot of real-world use is a multinational survey in which practitioners reported records for one scleral lens patient each (259 patients, 419 eyes). Indications were corneal irregularity in 87%, ocular surface disease in 9%, and uncomplicated refractive error in 4%.[1] Lens diameters ranged from 11.8 to 23.0 mm, with a mean of 16.2 mm.[1]
The two clinical jobs are different, and it helps to frame a referral around which one you are asking for:
- Optical: a fluid reservoir behind a rigid lens neutralizes most of the irregular anterior corneal surface. This is the indication in keratoconus, pellucid marginal degeneration, post-refractive ectasia, post-keratoplasty astigmatism, and corneal scarring.
- Therapeutic: the lens vaults the cornea and limbus, holds a reservoir of non-preserved saline against the surface, and shields it from lid shear and evaporation.[6] This is the indication in exposure keratopathy, neurotrophic keratopathy, limbal stem cell deficiency, ocular GVHD, Stevens-Johnson syndrome, and persistent epithelial defects.[6]
Many patients need both.
Referral triggers: irregular cornea
Consider referral when any of these apply:
- Spectacle BCVA limits function and a manifest refraction can’t close the gap, typically because of irregular astigmatism or higher-order aberrations.
- Corneal GP lenses have failed through decentration, edge lift, poor stability on a steep or decentered cone, or intolerance.
- Soft or hybrid options have been tried and do not give adequate acuity or comfort.
- Anisometropia or aniseikonia makes spectacle correction impractical.
- A graft is clear but optically poor, once the corneal surgeon considers it stable. (See scleral lenses and corneal transplants.)
The visual results in selected patients are substantial. In a retrospective series of 157 keratoconic eyes, mean logMAR BCVA improved from 0.50 in spectacles to 0.08 in scleral lenses.[2] That series included only eyes successfully fit for at least a year, so it describes what is achievable, not the odds of success for every referral.[2] After penetrating keratoplasty, 44 of 48 eyes (91.7%) in a university series reached 20/40 or better.[3]
There is also observational evidence linked to surgical avoidance. In a single-center review of 2,806 eyes with keratoconus or ectasia, scleral lens use was associated with a lower hazard of keratoplasty compared with no contact lens (adjusted HR 0.19).[4] Corneal GP use showed a similar association (HR 0.30).[4] This is a retrospective association; patients who succeed in lenses may differ from those who don’t.
Progression is a separate referral
A scleral lens is not a treatment for ectasia. In the keratoconus series above, 14.6% of eyes lost best-corrected scleral lens acuity during the study period, all attributed to keratoconus progression.[2]
The KERALINK randomized trial enrolled 60 patients aged 10 to 16 with progressive keratoconus. Over 18 months, progression in the study eye occurred in 7% of patients randomized to cross-linking versus 43% in the standard-care arm, which used spectacles or contact lenses as needed.[5] The authors concluded that CXL should be considered first-line treatment in progressive disease.[5]
In practice: if tomography shows progression, or the patient is young enough that progression is likely, refer for a CXL evaluation at the same time as, or before, the lens referral. Send the serial tomography to both.
Referral triggers: ocular surface disease
Scleral lenses are generally not initial therapy for ocular surface disease.[6] The 2017 TFOS DEWS II report places therapeutic contact lenses, both bandage soft lenses and scleral lenses, at step 3 of dry eye management.[6] In a practitioner survey cited in the same review, scleral lenses were typically prescribed after topical lubricants, topical steroids, cyclosporine, and punctal occlusion.[6]
Reasonable triggers include:
- persistent punctate or filamentary keratopathy despite maximal topical therapy
- exposure keratopathy from lagophthalmos, lid malposition, or proptosis
- neurotrophic keratopathy, including asymptomatic eyes with surface breakdown
- limbal stem cell deficiency, ocular GVHD, or chronic Stevens-Johnson sequelae
- a persistent epithelial defect (often co-managed with a cornea specialist; see ocular surface disease referrals)
In a tertiary-center series of 212 patients evaluated for ocular surface disease, patients had tried an average of 3.2 other interventions before scleral lenses.[7] Of the 115 who completed fitting, all but 2 met their therapeutic goal of improved comfort, surface protection, or resolution of keratopathy.[7]
Referral triggers at a glance
| Situation | Why it points to referral |
|---|---|
| Irregular cornea, spectacle BCVA inadequate | The fluid reservoir masks irregular astigmatism that spectacles cannot correct |
| Corneal GP failure or intolerance | The lens lands on the sclera, not the cone or graft junction |
| Clear but irregular graft | Vaults the graft; needs surgeon coordination |
| Refractory surface disease (step 3) | Continuous hydration and protection from lid shear |
| Progressive ectasia | Refer for CXL evaluation too; the lens does not stop progression |
Alternatives worth naming to the patient
For irregular corneas: corneal GP, hybrid, and specialty soft lenses; cross-linking for progression; intracorneal ring segments; and keratoplasty when no lens gives usable vision. For ocular surface disease: lubricants, anti-inflammatory therapy, punctal occlusion, autologous serum, amniotic membrane, and tarsorrhaphy.[6] Bandage soft lenses, particularly silicone hydrogels, have consistent evidence for improving epithelial healing and reducing pain in persistent epithelial defects.[10]
When you refer, the referral checklist covers what the fitter will need from you.
Common questions
Should I refer a keratoconus patient for scleral lenses or for cross-linking first?
They answer different questions. Cross-linking addresses progression; a scleral lens addresses optics. If there is documented or suspected progression, a CXL evaluation should not wait on the lens fit. The two are commonly pursued in parallel, and the fitter will want the tomography history either way.
Is a failed corneal GP fit required before referral?
No. A prior corneal GP trial is a common pathway, and its failure mode (decentration, intolerance, unstable fit over a graft) is useful information to send. But a patient whose cornea or surface makes a corneal lens a poor prospect can be referred directly.
Are scleral lenses appropriate for uncomplicated refractive error?
They are used for it, but it is a small share of fits and outcomes appear weaker. In a one-year prospective study, 58% of regular-cornea participants completed 12 months of wear, against 77% of those with irregular corneas.
When is ocular surface disease 'refractory' enough to refer?
There is no single threshold. Scleral lenses sit at step 3 of the TFOS DEWS II management algorithm, after lubricants and anti-inflammatory or occlusive therapy. Persistent epitheliopathy, exposure, neurotrophic disease, or a persistent epithelial defect despite those measures are reasonable triggers.