What are the treatment options for a patient with Keratoconus?

Treatment Options for Keratoconus

For patients with keratoconus, corneal collagen cross-linking (CXL) is the primary treatment to halt disease progression once documented progression is confirmed, while specialty contact lenses remain the mainstay for visual rehabilitation, and keratoplasty is reserved for advanced cases unresponsive to conservative measures. 1

Halting Disease Progression: Corneal Cross-Linking

CXL should be performed promptly when progression is documented to prevent further vision loss and reduce the need for corneal transplantation. 2, 1

Indications for CXL

• CXL is indicated for documented progressive keratoconus, defined by at least 2 of the following: steepening of the anterior corneal surface, steepening of the posterior corneal surface, or thinning/increased rate of corneal thickness change from periphery to thinnest point 1
• Documentation of progression requires serial topographic analysis comparing at least two examinations taken 3-6 months apart 1, 3
• Pediatric patients with keratoconus require closer follow-up, especially those under 17 years with Kmax >55D 1

Efficacy of CXL

• CXL stops deterioration and progression in the majority of patients, with long-term studies confirming stability beyond 36 months 1
• FDA clinical trials demonstrated that progressive keratoconus patients had an average Kmax reduction of 1.4-1.7 diopters at 12 months in CXL-treated eyes, while sham eyes had an average increase of 0.5-0.6 diopters 4
• The treatment difference between CXL and sham groups was -1.9 to -2.3 diopters for keratoconus patients 4
• European studies report significant reductions in keratoplasty rates since CXL introduction, and the long-term stabilizing effect of CXL may be more cost-effective than corneal transplantation 1

Safety Threshold

• Standard CXL protocols require corneal thickness of at least 400 μm to avoid endothelial damage 3
• For thinner corneas with documented progression, modified approaches may be considered, such as hypotonic riboflavin to transiently thicken the cornea, though these are not FDA-approved in the United States 3

Visual Rehabilitation: Non-Surgical Options

Eyeglasses

• Eyeglasses can correct vision in early keratoconus, with 71% of patients achieving 20/40 or better vision 1

Contact Lenses

Rigid gas-permeable (RGP) contact lenses are the primary treatment for visual rehabilitation in moderate to advanced keratoconus, masking corneal irregularities by providing a regular anterior refractive surface. 1

• Soft contact lenses (spherical or toric) may provide acceptable vision with greater comfort than rigid lenses in mild cases 1
• RGP lenses are most frequently used in conservative treatment of keratoconus, achieving significantly better best-corrected visual acuity (0.82 Snellen) compared to spectacles (0.37 Snellen) 5
• Scleral lenses should be trialed prior to keratoplasty and may delay or eliminate the need for corneal transplantation 1, 6
• Hybrid contact lenses (rigid center with soft skirt) offer higher oxygen permeability and may improve comfort 1

Surgical Interventions for Advanced Disease

Penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) are reserved for advanced cases unresponsive to conservative measures, with DALK preferred when technically feasible. 1, 6

DALK Advantages

• DALK offers no risk of endothelial rejection, lower risk of stromal rejection, and less progressive endothelial cell loss following surgery compared to PK 2, 1
• DALK also has a lower risk of globe rupture compared to PK 1, 6

Keratoplasty Indications

• Less than 20% of keratoconus cases historically required penetrating keratoplasty 2
• Overall, the rate of keratoplasty in keratoconus is decreasing in the United States 2
• Improved imaging technologies allow for early identification of keratoconus, making the true incidence of progression to keratoplasty much lower than previously thought 2

Adjunctive Measures to Prevent Progression

Eye Rubbing Cessation

Patients must be counseled to refrain from eye rubbing, which is strongly associated with keratoconus progression. 1, 6

• Eye rubbing, family history, and younger age of onset may result in greater progression of disease, resulting in more severe loss of vision due to greater irregular astigmatism, thinning, and scarring 2
• A behavior modification approach for controlling chronic habits of abnormal rubbing has been suggested to prevent progression of keratoconus 2

Management of Allergic Eye Disease

• For patients with comorbid allergic eye disease, first-line treatment includes cool compresses, preservative-free artificial tears, antihistamines, and mast cell stabilizers 1
• Second-line treatment includes topical cyclosporine 0.05-0.1% for moderate-to-severe allergic conjunctivitis 1
• Vernal and atopic keratoconjunctivitis should be controlled prior to CXL to decrease sterile keratitis risk 1
• Patients with vernal keratoconjunctivitis may need corneal transplant surgery earlier compared with those who did not have it, and patients with atopy have higher risk for developing corneal hydrops 2, 6

Treatment Algorithm

1. Early/Mild Keratoconus (No Documented Progression):

   • Correct vision with eyeglasses or soft contact lenses 1
   • Monitor with serial topography every 3-6 months to detect progression 1, 3
   • Counsel on eye rubbing cessation and manage allergic eye disease 1, 6

2. Progressive Keratoconus (Documented on Serial Topography):

   • Perform CXL immediately to halt progression 2, 1
   • Continue visual rehabilitation with contact lenses as needed 1

3. Moderate to Advanced Keratoconus (Stable or Post-CXL):

   • Fit with RGP or scleral contact lenses for visual rehabilitation 1, 6
   • Consider hybrid lenses if comfort is an issue 1

4. Advanced Keratoconus (Contact Lens Intolerance or Corneal Scarring):

   • Refer for DALK (preferred) or PK 1, 6
   • Trial scleral lenses before proceeding to keratoplasty 1, 6

Common Pitfalls and Caveats

• Do not delay CXL in patients with documented progression—waiting for additional vision loss increases the risk of requiring corneal transplantation 2, 6
• Do not perform CXL without documented progression—this exposes patients to unnecessary risks without clear benefit 3
• Do not proceed with standard CXL on corneas thinner than 400 μm without appropriate modifications—this risks endothelial damage 3
• Do not overlook the importance of eye rubbing cessation—many patients may not be fully aware of the extent to which they rub their eyes and inadvertently worsen their disease 2
• Patients with vernal or atopic keratoconjunctivitis require aggressive disease management—they have higher risk for corneal hydrops (acute Descemet's membrane rupture occurring in approximately 3% of keratoconus patients) and may require earlier surgical intervention 2, 6