What are the treatment options for Terrien's Marginal Degeneration?

Treatment Options for Terrien's Marginal Degeneration

For Terrien's Marginal Degeneration (TMD), surgical intervention with lamellar keratoplasty is the most effective treatment for advanced cases with significant thinning, ectasia, or imminent perforation. 1, 2

Disease Characteristics

• TMD is a slow-progressing, bilateral but asymmetric degeneration of the peripheral cornea, more commonly affecting men over 40 years of age 2
• Classic signs include stromal thinning, vascularization, lipid deposition, and against-the-rule astigmatism 2
• Mean topographic astigmatism is approximately 4.02 diopters, with progression of about 0.75D at 1 year and 1.68D at 3 years 2
• Though typically non-inflammatory, a variant form with prominent inflammation exists 2
• Perforation is rare but can result in significant vision loss when it occurs 2

Treatment Algorithm

Non-surgical Management (Early Stage)

• Correction of refractive error with spectacles or contact lenses for mild cases with good visual acuity 3
• Management of ocular surface inflammation when present (56% of cases) with appropriate anti-inflammatory medications 2
• Regular monitoring for disease progression, as TMD typically advances slowly 2

Surgical Interventions (Advanced Stage)

1. Anterior Lamellar Therapeutic Keratoplasty (ALTK)

   • Indicated for peripheral thinning and ectasia to provide tectonic support 1
   • May require concentric donut or partial crescentic grafts for annular pathology 1
   • Donor tissue options include partial-thickness irradiated tissue, glycerin-preserved tissue, or eye bank preserved tissue 1

2. Crescentic Patch Grafts

   • Specifically recommended for TMD with significant tissue loss and increased astigmatism 1
   • May be partial or full-thickness, taking oval or crescentic forms 1
   • Provides both tectonic support and astigmatism correction 1

3. Two-step Annular Lamellar Keratoplasty

   • Effective for severe cases with peripheral corneal thinning and ectasia around the entire corneal circumference 4
   • Involves removing the annular-shaped ectatic lesion and replacing with donor tissue of the same size and shape 4
   • Allows control of corneal astigmatism through suture management 4

4. Primary Surgical Repair

   • For severe peripheral marginal ectasia 5
   • Involves incising the area of ectasia along its thinnest paralimbal dimension, undermining ectatic stroma, and suturing normal-thickness stroma together 5
   • Can substantially improve visual acuity and decrease corneal astigmatism 5

5. Penetrating Keratoplasty (PK)

   • Reserved for cases with perforation or when lamellar techniques are not feasible 1
   • May require oversized or tectonic grafts when the pathologic process extends beyond the central 7.5-9.0 mm 1
   • In some cases, staged treatment is necessary with an initial eccentric corneal patch followed by conventional PK months later 1

Management of Complications

• Corneal Hydrops: Often characterized by a clear intracorneal pocket of aqueous humor rather than stromal clouding; most cases can be observed without treatment unless there is severe astigmatism, hypotony, or impending perforation 6
• Perforation: Requires immediate surgical intervention, typically with lamellar grafting 2
• Pseudopterygium: May develop in approximately 6.9% of cases and should be monitored 2
• Intracorneal Cysts: Occur in about 4.7% of cases and generally don't require specific treatment 2

Surgical Outcomes

• Eyes requiring surgery (23.3% of cases) typically have poorer visual outcomes, with mean best spectacle-corrected visual acuity (BSCVA) of 20/81 at presentation and 20/106 after surgery 2
• Despite this, surgery is essential to preserve corneal integrity when conventional options fail to maintain vision or if perforation is imminent 2
• Femtosecond laser-assisted keratoplasty may offer advantages through better wound healing and stronger interfaces compared to conventional techniques 1

Pitfalls and Caveats

• Regular monitoring is essential as TMD can progress unpredictably, with mean change in astigmatism of 1.68D over 3 years 2
• Surgical intervention should not be delayed when significant thinning or ectasia develops, as perforation can occur spontaneously (4 out of 5 perforations in one study) 2
• Post-surgical management of astigmatism is challenging and may require specialized contact lenses 2
• Sutures in TMD repairs are often left in place permanently to maintain corneal integrity 5