Start with the indication
Indication is the clearest outcome signal in the literature. In a prospective study of 95 consecutive participants followed for 12 months, 77% of those with irregular corneas completed the year in scleral lenses, against 58% of those with regular corneas.[1] Overall, 73% completed the year; none of the discontinuations were due to adverse events.[1]
In long-term PROSE data from a single center, 121 patients had five-year follow-up. Continued wear at five years was more likely with distorted cornea (84%) than with ocular surface disease (64%), although the authors note this did not hold across every subgroup within ocular surface disease.[4] In a retrospective series of 31 patients with chronic ocular GVHD fitted with mini-scleral lenses, 22.6% discontinued over a median follow-up of about two years.[5]
The practical reading: an irregular cornea with a large gap between spectacle and potential acuity is the most predictable referral. Surface disease referrals are worthwhile but carry a higher chance the patient stops, which is worth saying to the patient before they go.
Handling is the main reason people stop
Across three different cohorts, insertion and removal was the leading reason for discontinuation:
- Prospective, mixed indications (n=95): handling issues accounted for 35% of discontinuations, discomfort for 19%.[1]
- Retrospective, veterans (n=120): difficulty with insertion and removal accounted for 53.7% of discontinuations.[2]
- Retrospective, post-keratoplasty (48 eyes): insertion or removal difficulty was the most common reason, in 8 of the 19 eyes that discontinued (42.1%).[3]
Handling usually improves with practice. In the prospective study, the number of attempts needed to apply and remove lenses fell significantly over the year among those who continued.[1] At the dispensing visit, 36% applied the lens correctly in under 15 minutes, while 13% needed more than 60 minutes; that slower group had worn spectacles, soft lenses, or no correction at baseline.[1]
Factors associated with discontinuation
The veteran cohort is the most useful single source here, with caveats: it is retrospective, single-center, and older (mean age 56.7) than most keratoconus populations.[2]
- Neurologic comorbidity. Comorbid neurologic disease was significantly associated with discontinuation (odds ratio 4.6, 95% CI 1.3 to 17).[2] The wide interval reflects a small number of events; treat it as a signal, not a precise estimate.
- Smaller visual gain and shorter wear time. Patients who continued had significantly greater visual acuity improvement and longer daily wear than those who stopped.[2]
- Subjective vision. After keratoplasty, patients who continued were more likely to rate their vision as “good,” even though the change in measured BCVA did not differ significantly between those who continued and those who stopped.[3]
- Wear difficulties were common overall. 55.0% of the veterans reported difficulty with wear, most often ocular irritation (20.0%) and mid-day fogging or bubbles (15.8%).[2]
Age was not significantly different between those who continued and those who stopped in that cohort.[2]
Ocular factors that change the plan, not the referral
These deserve a clear line in your referral letter:
- Prior keratoplasty. Grafts have reduced endothelial reserve and can swell under a lens. Baseline and follow-up pachymetry and specular microscopy may be considered.[6] See scleral lenses and corneal transplants.
- Incisional glaucoma surgery. At one PROSE center, 3 of 5 eyes with prior incisional glaucoma surgery were successfully fit.[7] In a 15-year academic series of 39 eyes with bleb-forming surgery, 51% achieved at least one year of successful contact lens wear of any type; corneal GP lenses were more common among the successes, and non-impression-fitted scleral lenses more common among the failures.[8]
- Immunosuppression, diabetes, or non-healing epithelial defects. These patients should be monitored closely for complications.[6] In a case series of three post-keratoplasty scleral lens wearers who developed microbial keratitis, all had concurrent surface disease and all were on topical or systemic immunosuppression.[9]
- Symblepharon or partial tarsorrhaphy. These may limit lens diameter.[6]
Patient factors at a glance
| Generally favorable | Flag for the fitter |
|---|---|
| Irregular cornea with a large gap between spectacle BCVA and potential acuity | Regular cornea, small expected visual gain |
| Motivated by a specific functional goal (driving, work, reading) | Neurologic disease, tremor, arthritis, or reduced dexterity |
| Prior rigid lens experience | No prior lens wear (slower initial handling) |
| Caregiver available if needed | Lives alone with limited vision in the fellow eye |
| Stable ocular disease | Graft, glaucoma surgery, immunosuppression, or active surface breakdown |
Don’t screen out on age
A review of therapeutic scleral lens use states there are no age restrictions: children can be fit with caregivers trained to apply and remove the lens, and geriatric patients should not be excluded on age alone.[6] In a PROSE study cited in that review, application and removal times did not differ between younger and older patients.[6] A 21-year single-center pediatric review found most eyes still wearing lenses at last review, with application and removal challenges the main reason among the minority who stopped.[10]
The referral checklist lists what to include so the fitter can plan around these factors from the first visit.
Common questions
Is a neurologic diagnosis a contraindication to scleral lenses?
No published source treats it as one. In one retrospective veteran cohort it was associated with higher odds of discontinuation, with a wide confidence interval. Flag it in the referral so the fitter can assess dexterity and plan for aids or a caregiver.
Is there an upper age limit?
Not in the literature reviewed here. Age did not differ between veterans who continued and those who discontinued, and a review of therapeutic scleral lens use states that geriatric patients should not be excluded on age alone.
Should I hold off referring a patient with a trabeculectomy or tube?
Not necessarily, but say so prominently. Success rates in eyes with incisional glaucoma surgery are lower in small published series, and bleb or tube location affects lens design.
Does the patient need good vision in the fellow eye to handle the lens?
It helps, but it isn't required. Lighted inserters and insertion stands exist for patients with poor vision or limited dexterity, and caregivers can be trained to apply and remove lenses.