Short note on scleral contact lens and PROSE
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Scleral contact lens
A scleral contact lens is a large-diameter rigid gas-permeable lens that rests on the sclera and vaults over the cornea, creating a fluid reservoir between its posterior surface and the cornea.
Functions
- Provides a smooth anterior optical surface, improving vision in irregular cornea.
- Maintains continuous lubrication and protection of the corneal epithelium.
- Shields the ocular surface from lid friction and environmental exposure.
Indications
- Corneal ectasia: keratoconus, pellucid marginal degeneration, post-LASIK ectasia.
- Irregular cornea following corneal graft, trauma, or infection.
- Ocular surface disease: severe dry eye, Sjogren syndrome, graft-versus-host disease, Stevens-Johnson syndrome, ocular cicatricial pemphigoid.
- Persistent epithelial defects and neurotrophic keratopathy.
- Occasionally for high ametropia when conventional correction is unsuitable.
Advantages
- Excellent comfort because the lens bears on relatively insensitive sclera rather than cornea.
- Better centration and stability than smaller rigid lenses.
- Can markedly improve both visual acuity and ocular comfort.
Limitations/complications
- Requires expert fitting, insertion, removal, and meticulous cleaning.
- Fogging of the fluid reservoir, lens handling difficulty, conjunctival blanching/compression, hypoxia-related corneal edema, suction on removal, and microbial keratitis if hygiene is poor.
- Fill only with preservative-free sterile saline as advised by the fitter.
PROSE
PROSE stands for Prosthetic Replacement of the Ocular Surface Ecosystem. It is a highly customized therapeutic scleral lens treatment developed by BostonSight. It is not simply a lens product: it is a clinical treatment system involving detailed ocular-surface assessment, individualized device design, fitting, and follow-up.
Mechanism
The PROSE device vaults the cornea and is filled with preservative-free saline. The resulting protected, hydrated liquid environment supports epithelial healing, reduces pain and photophobia, and corrects optical irregularity.
Main uses
- Severe ocular surface disease and dry eye
- Persistent epithelial defects and neurotrophic keratopathy
- Chemical or thermal ocular injury
- Cicatrizing conjunctival diseases, including Stevens-Johnson syndrome and ocular cicatricial pemphigoid
- Graft-versus-host disease
- Irregular cornea and corneal scarring
Key distinction: all PROSE devices are scleral-lens based, but not every scleral lens is a PROSE device. PROSE refers specifically to the individualized therapeutic program and device system. BostonSight describes it as a treatment designed to restore visual and physiological function in ocular-surface and corneal disease. BostonSight’s PROSE overview
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Scleral Contact Lens and PROSE
Introduction
Scleral contact lenses are large-diameter rigid gas-permeable contact lenses designed to rest entirely on the sclera, the white part of the eye. Unlike conventional corneal rigid lenses, they vault over the cornea and limbus without touching them. The space between the posterior surface of the lens and cornea is filled with preservative-free sterile saline at insertion, forming a continuous fluid reservoir.
Thus, scleral lenses serve two major purposes:
- Optical rehabilitation by creating a regular refracting surface over an irregular cornea.
- Therapeutic ocular-surface protection by keeping the cornea bathed in fluid and protected from blinking, exposure, and environmental irritation.
They are used in corneal ectasia and severe ocular-surface disorders, and can also be used as a temporary protective cap in selected cases of severe corneal thinning or descemetocele. Kanski's Clinical Ophthalmology: A Systematic Approach, 10th ed., section “Preservation of corneal integrity.”
1. Structure and design of a scleral lens
A scleral lens has three principal zones:
| Zone | Location and role |
|---|---|
| Optical zone | Central portion overlying the cornea. It provides refractive correction. |
| Vault or sagittal-depth zone | Creates clearance over the cornea and limbus, allowing a fluid reservoir to remain beneath the lens. |
| Haptic or landing zone | Peripheral part that rests on the conjunctiva overlying the sclera and supports the lens. |
Most modern scleral lenses are made from highly oxygen-permeable rigid gas-permeable materials. Diameter may range from about 14.5 mm to more than 20 mm. Larger lenses provide greater corneal vault and stability but are more difficult to handle and require more detailed fitting.
How it works
When placed on the eye after being filled with sterile preservative-free saline:
- The lens masks irregularities in the anterior corneal surface.
- The tear reservoir neutralizes irregular astigmatism and reduces optical scatter.
- The cornea remains continuously hydrated.
- The lens acts as a barrier against desiccation, eyelid friction, trichiasis, and external irritants.
In corneal ectasia, such as keratoconus, the contact lens creates a smooth refracting surface that can substitute for the distorted corneal optical surface. Guyton and Hall Textbook of Medical Physiology, 14th ed., section “See Video 50.1.”
2. Types of scleral lenses
Scleral lenses may be classified by diameter and the area on which they rest.
| Type | Approximate diameter | Site of bearing |
|---|---|---|
| Corneo-scleral lens | 12.5-15 mm | Cornea and sclera |
| Semi-scleral lens | 15-18 mm | Mainly sclera |
| Mini-scleral lens | 15-18 mm | Sclera |
| Full scleral lens | 18-25 mm | Sclera, with complete corneal vault |
In routine clinical use, the terms mini-scleral, semi-scleral, and scleral lens are often used broadly for large rigid lenses that vault the cornea and land on the sclera.
3. Indications for scleral contact lenses
A. Corneal irregularity and visual rehabilitation
Scleral lenses are especially valuable when spectacles and conventional soft contact lenses cannot provide satisfactory vision.
Common indications include:
- Keratoconus
- Pellucid marginal degeneration
- Keratoglobus
- Post-LASIK or post-PRK ectasia
- Corneal scarring after trauma or keratitis
- Irregular astigmatism after penetrating keratoplasty
- Post-radial keratotomy irregularity
- Corneal dystrophies with irregular astigmatism
- Irregular cornea following refractive or other corneal surgery
In these conditions, the lens-fluid system creates a regular anterior optical surface and can substantially improve corrected visual acuity.
B. Ocular-surface disease
Scleral lenses have a protective therapeutic role in severe ocular-surface disease. The fluid reservoir reduces pain, dryness, photophobia, and mechanical trauma to the epithelium.
Examples:
- Severe dry-eye disease
- Sjogren syndrome
- Graft-versus-host disease
- Stevens-Johnson syndrome and toxic epidermal necrolysis
- Ocular cicatricial pemphigoid
- Chemical or thermal ocular burns
- Exposure keratopathy
- Neurotrophic keratopathy
- Limbal stem-cell deficiency
- Persistent epithelial defects
- Filamentary keratitis
- Severe meibomian gland dysfunction-associated ocular-surface disease
The Wills Eye Manual includes scleral lenses among treatment options for severe dry eye and notes that a scleral lens, including PROSE, may be useful for long-term management in selected patients with neurotrophic keratopathy. The Wills Eye Manual, section “Severe Dry Eye” and section “Treatment.”
C. Other uses
- Protection of a fragile cornea in selected cases of corneal thinning.
- Relief of pain in bullous keratopathy in selected patients.
- Cosmetic masking in a disfigured eye, when appropriate.
- Correction of high refractive errors in patients who cannot tolerate other lens forms.
4. Advantages of scleral lenses
Optical advantages
- Correct irregular astigmatism better than spectacles in many corneal disorders.
- Provide stable, centered optics.
- May improve visual quality, contrast, and reduce glare or ghost images.
- Less likely to dislodge than small corneal rigid lenses.
Therapeutic advantages
- Continuous hydration of the corneal surface.
- Reduced evaporative stress in dry eye.
- Protection from blinking-related friction.
- Reduction in pain, foreign-body sensation, photophobia, and exposure-related symptoms.
- Can promote epithelial healing by maintaining a protected moist environment.
Mechanical advantages
- The lens rests on the sclera, which is less sensitive than the cornea.
- Comfort may be better than with smaller corneal rigid gas-permeable lenses after adaptation.
- Large diameter improves stability and centration.
5. Fitting principles
Scleral lens fitting requires assessment by a trained eye-care practitioner. It is not a simple “trial and dispense” procedure.
Pre-fitting evaluation
The clinician evaluates:
- Visual acuity and refraction
- Corneal topography or tomography
- Ocular-surface condition
- Tear film and eyelids
- Corneal staining
- Conjunctival abnormalities
- Corneal thickness and endothelial health, especially in grafted or compromised corneas
- Presence of glaucoma filtering blebs, drainage devices, or other ocular surgery
Desired fitting relationship
A properly fitted lens should show:
-
Central corneal vault
The lens should clear the corneal apex without touch. -
Limbal clearance
The limbus must be adequately vaulted to avoid mechanical trauma to limbal stem cells. -
Appropriate scleral alignment
The haptic should rest evenly on the conjunctiva, avoiding focal pressure, excessive edge lift, or blanching of conjunctival blood vessels. -
Adequate oxygen transmission
Lens material, thickness, duration of wear, and fluid-reservoir thickness should minimize hypoxic stress. -
Good vision and comfort
The aim is not merely a lens that remains on the eye, but one that achieves sustained vision, comfort, and ocular-surface health.
Modern fitting often uses corneal topography, scleral profiling, anterior-segment OCT, or impression-based and image-guided customization.
6. Insertion, removal, and maintenance
Insertion
The lens bowl is filled completely with preservative-free sterile saline before application. The patient must avoid trapping an air bubble under the lens because a bubble can cause discomfort, blur vision, and produce focal corneal desiccation.
Typical steps:
- Wash and dry hands thoroughly.
- Clean and rinse the lens as instructed.
- Fill the lens completely with prescribed preservative-free saline.
- Hold the eyelids widely open.
- Apply the lens directly to the eye while keeping the face directed downward.
- Check for comfort, clear vision, and absence of a central air bubble.
Removal
Removal is performed using a small suction device or by breaking the seal at the lower edge of the lens. The lower eyelid may be pulled beneath the lens edge to lift it away from the ocular surface. Roberts and Hedges’ Clinical Procedures in Emergency Medicine, section “Removal of a Hard Scleral Lens.”
Maintenance
Important rules include:
- Use only the recommended cleaning and disinfection system.
- Do not use tap water to rinse or fill the lens.
- Do not use preserved multipurpose contact-lens solution in the lens reservoir unless specifically advised.
- Use preservative-free sterile saline for filling.
- Replace the storage case regularly.
- Follow scheduled reviews, even if vision and comfort are good.
7. Complications and problems
Although scleral lenses can be highly successful, complications can arise from poor fit, poor hygiene, excessive wearing time, ocular-surface disease, or inadequate follow-up.
| Complication/problem | Possible cause | Management principle |
|---|---|---|
| Midday fogging | Debris, lipid, mucin, inflammatory cells, tear-film instability | Remove, clean, refill; optimize fit and ocular-surface disease |
| Blurred vision after hours of wear | Fogging, surface deposits, corneal edema, unstable tear film | Examine fit, material, reservoir thickness, and ocular surface |
| Conjunctival blanching | Excessive haptic pressure | Modify landing zone |
| Conjunctival impingement or compression | Tight or poorly aligned edge | Refit or customize haptic |
| Redness after removal | Compression, suction, hypoxia, inflammation | Assess fit and wearing schedule |
| Lens awareness/discomfort | Edge lift, poor surface wetting, dry eye, debris | Treat surface disease and adjust design |
| Corneal edema | Reduced oxygen availability, thick lens or fluid reservoir, endothelial dysfunction | Reduce hypoxic burden and reassess suitability |
| Epithelial staining | Mechanical bearing, trapped debris, poor limbal clearance | Refit and treat ocular surface |
| Microbial keratitis | Poor hygiene, contaminated solutions, overnight wear, epithelial compromise | Urgent ophthalmic assessment; stop lens wear unless specifically directed otherwise |
| Difficulty removing lens | Excessive suction or tight fit | Break the seal correctly; refit if recurrent |
Patients should seek urgent ophthalmic care for persistent pain, sudden redness, photophobia, discharge, reduced vision, or a corneal white spot.
Important cautions
Scleral lens use needs special consideration in:
- Low corneal endothelial cell counts
- Corneal grafts
- Active corneal infection
- Severe limbal ischemia
- Glaucoma drainage devices or filtering blebs
- Significant conjunctival scarring
- Patients unable to maintain proper lens hygiene or insertion technique
PROSE
8. Definition
PROSE stands for Prosthetic Replacement of the Ocular Surface Ecosystem.
It is a highly customized, medically supervised scleral-lens treatment developed by BostonSight. PROSE is not simply another name for every scleral lens. It refers to a specialized therapeutic system involving:
- Detailed ocular-surface assessment
- Individualized device design
- Precise fitting and modification
- Education on application, removal, and care
- Follow-up focused on visual function and ocular-surface rehabilitation
BostonSight defines PROSE as a medical treatment using highly customized scleral devices to restore visual and physiological function in people with ocular-surface disease, corneal disease, injury, or damage. BostonSight’s PROSE description
9. Construction and mechanism of the PROSE device
A PROSE device is a customized large-diameter rigid gas-permeable scleral device. Like other scleral lenses, it:
- Rests on the sclera.
- Vaults the cornea and limbus.
- Is filled with preservative-free saline.
- Maintains a fluid reservoir over the corneal epithelium.
- Provides a smooth optical surface.
Therapeutic mechanism
The PROSE device acts as an artificial protective ocular environment. It can:
- Maintain corneal hydration.
- Reduce desiccation and tear-film evaporation.
- Protect the cornea from friction caused by blinking or abnormal eyelids.
- Reduce pain and photophobia.
- Support healing of persistent epithelial defects.
- Correct irregular corneal optics and improve vision.
Therefore, PROSE is particularly valuable where a patient has both severe ocular discomfort and reduced vision from an irregular or damaged corneal surface.
10. Indications for PROSE treatment
A. Severe ocular-surface disease
PROSE is most widely recognized for severe, refractory ocular-surface disorders, particularly when standard lubricants, anti-inflammatory therapy, punctal occlusion, serum tears, eyelid procedures, or soft bandage lenses are inadequate.
Important indications include:
- Severe aqueous-deficient dry eye
- Sjogren syndrome
- Chronic graft-versus-host disease
- Stevens-Johnson syndrome
- Toxic epidermal necrolysis
- Ocular cicatricial pemphigoid
- Chemical injury and thermal burns
- Exposure keratopathy
- Neurotrophic keratopathy
- Persistent corneal epithelial defects
- Limbal stem-cell deficiency
- Severe ocular-surface disease after radiation or surgery
B. Corneal irregularity
PROSE may also be prescribed for:
- Keratoconus
- Pellucid marginal degeneration
- Post-keratoplasty irregular astigmatism
- Post-refractive surgery ectasia
- Corneal scars
- Corneal dystrophies
- Irregular astigmatism after trauma or infection
11. PROSE in neurotrophic keratopathy
Neurotrophic keratopathy is characterized by reduced corneal sensation and impaired epithelial healing. Because the patient may have little pain despite serious epithelial damage, it can progress to persistent defects, ulceration, stromal melting, or perforation.
PROSE may be helpful because it:
- Provides a fluid-protected environment.
- Minimizes mechanical trauma.
- Supports epithelial repair.
- Improves visual function if corneal irregularity is present.
The Wills Eye Manual specifically lists a scleral lens such as PROSE as a potential long-term treatment in this setting. The Wills Eye Manual, section “Treatment.”
However, patients with neurotrophic disease require close monitoring because reduced sensation can mask worsening infection or epithelial breakdown.
12. PROSE in severe dry eye and cicatrizing disease
In severe dry eye, the ocular surface becomes unstable because of insufficient tears, inflammation, epithelial damage, lid disease, or conjunctival scarring. A PROSE device protects the cornea from exposure and continuously bathes it in fluid during wear.
It can be useful in conditions such as:
- Sjogren syndrome
- Chronic graft-versus-host disease
- Stevens-Johnson syndrome
- Ocular cicatricial pemphigoid
Expected benefits may include:
- Reduced dryness and burning
- Reduced foreign-body sensation
- Less photophobia
- Improved ability to keep the eye open
- Improved functional vision
- Better quality of life and ability to work, read, use screens, or tolerate outdoor environments
A recent review describes PROSE as providing sustained corneal humidity, positional stability, and protection against lid shearing forces in ocular-surface disease. Review of scleral lens outcomes
13. Scleral lens versus PROSE
| Feature | Conventional scleral lens | PROSE |
|---|---|---|
| Basic design | Large rigid gas-permeable lens vaulting the cornea | Highly customized scleral device |
| Main purpose | Vision correction and/or surface protection | Medical treatment for ocular-surface and corneal disease |
| Fitting | Can range from standard diagnostic fitting to customized fitting | Specialized individualized fitting and follow-up program |
| Indications | Irregular cornea, ectasia, dry eye, selected ocular-surface disease | Severe ocular-surface disease, corneal disease, injury, and complex irregular cornea |
| Fluid reservoir | Yes | Yes |
| Relation | Broad category of lenses | A specific therapeutic scleral-lens system |
Key point:
All PROSE devices are scleral devices, but all scleral lenses are not PROSE devices.
All PROSE devices are scleral devices, but all scleral lenses are not PROSE devices.
14. Limitations of PROSE and scleral lenses
Despite their benefits, these devices are not suitable for every patient.
Limitations include:
- Cost and availability of specialized fitting.
- Need for multiple fitting visits.
- Handling difficulty, particularly in patients with poor hand function, tremor, reduced vision, or anxiety.
- Need for strict hygiene.
- Ongoing treatment of the underlying disease. A lens does not cure autoimmune disease, lid abnormality, severe inflammation, infection, or limbal stem-cell failure.
- Risk of hypoxia, fogging, deposits, conjunctival compression, and infection if used inappropriately.
The evidence base is largely observational for several rare ocular-surface disorders. Reviews report encouraging outcomes, but randomized controlled trial data are limited for many indications. Therapeutic scleral lens review
15. Conclusion
Scleral contact lenses are large rigid gas-permeable lenses that vault the cornea, rest on the sclera, and retain a saline reservoir over the ocular surface. They improve vision by masking corneal irregularity and provide therapeutic protection by maintaining corneal hydration and reducing mechanical trauma.
PROSE is a specialized, highly customized scleral-device treatment system used particularly for severe ocular-surface disease, neurotrophic keratopathy, persistent epithelial defects, cicatrizing conjunctival disorders, and irregular cornea. Its benefits arise from both optical correction and creation of a stable, protective fluid environment over the cornea.
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