33-year-old healthy female with history of LASIK OU in 2004 presented with blurred vision in both eyes for several months duration, left worse than right
Denies eye pain but complains of problems with glare at night
Normal external exam
Refraction with high sphere and high astigmatism prescription
Corneal topography with high irregular astigmatism
Forme Fruste Keratoconus
Pellucid Marginal Degeneration
Additional Clinic Photos
Incidence rate of 0.04 percent-0.6 percent occurring primarily after LASIK and usually developing within one-year post-procedure.
Histopathologic findings include interlamellar and interfibrillar slippage through disruption of lamellar bonds in the stroma isolated to ectatic regions only. Additional findings include breaks in Bowman’s layer and larger than normal interlamellar clefts.
LASIK flap no longer contributes to the tensile strength of the cornea so residual stromal bed thickness (RSB) is remaining load bearing tissue.
Ectasia risk criteria for predicting which patients are at greatest risk of developing post-LASIK ectasia based on: 1. abnormal pre-operative topography, 2. low RSB, 3. young age, 4. low pre-op corneal thickness, and 5. high myopia.
Percent tissue altered (PTA) takes into account many of these factors (corneal thickness, ablation depth from myopia, and flap thickness) to provide a more individualized screening metric.
Contact lenses (RGPs)
Intracorneal Ring Segments
Penetrating Keratoplasty (PKP)
Corneal Cross-linking (CXL)
Prognosis and Future Directions
Corneal cross-linking using the standard protocol with epithelial removal and 30-minute treatment duration has been shown to halt the ectatic process in more than 95 percent of treated eyes. This treatment has been proven effective in post-LASIK ectasia as well as keratoconus, and long-term results show good stability over 10-year follow-up. The standard protocol is now FDA-approved for use in the US and is being offered at the USC Roski Eye Institute.
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Richoz O, Mavrakanas N, Pajic B, Hafezi F. Corneal Collagen Cross-Linking for Ectasia after LASIK and Photorefractive Keratectomy. Ophthalmology (2013); 120(7):1354-1359.
Raiskup F, Theuring A, Pillunat LE, Spoerl E. Corneal Collagen Crosslinking with Riboflavin and Ultraviolet- A Light in Progressive Keratoconus: Ten-Year Results. J Cataract Refract Surg. 2015 Jan; 41(1):41-46.