Iatrogenic ectasia

Ectasia after photoablation is to refractive surgery what hydrops is to keratoconus: the dreaded complication, because it turns a healthy eye into a diseased one. Its pathophysiology is biomechanical weakening pushed beyond the threshold where the cornea no longer holds its shape — a predisposed cornea, an over-aggressive procedure, most often both.

Prevention rests entirely on preoperative screening and respecting the limits. The Randleman score (ERSS) aggregates topography, residual bed, age, thickness, spherical equivalent; the PTA captures global biomechanical insult in one number. Add posterior-surface tomography and dynamic biomechanical assessment, which detect the formes frustes that Placido topography alone misses. Once established, management mirrors keratoconus: cross-linking to stabilise, intracorneal rings to regularise, lamellar keratoplasty as a last resort.

Comparative synthesis

The choice reduces to three axes: comfort/speed, respect for load-bearing tissue, complication profile.

These categories do not replace the examination: it is the patient's cornea — thickness, topography, biomechanics — that ultimately designates the technique. The surgeon's role is less to prefer a procedure than to recognise, for each eye, the one that corrects without weakening.

Publications & sources

1. Munnerlyn CR, Koons SJ, Marshall J. Photorefractive keratectomy: a technique for laser refractive surgery. J Cataract Refract Surg. 1988. — ablation formula.
2. Randleman JB, Woodward M, Lynn MJ, Stulting RD. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology. 2008. — Ectasia Risk Score System.
3. Santhiago MR, Smadja D, Gomes BF, et al. Percent tissue altered and post-LASIK ectasia in eyes with normal topography. Am J Ophthalmol. 2014.
4. Santhiago MR, Smadja D, Wilson SE, et al. Role of percent tissue altered on ectasia after LASIK in suspicious topography. J Refract Surg. 2015.
5. Dupps WJ, Wilson SE. Biomechanics and wound healing in the cornea. Exp Eye Res. 2006.
6. Netto MV, Mohan RR, Wilson SE, et al. Wound healing in the cornea: haze and myofibroblasts.
7. Sekundo W, Blum M, et al. Small incision lenticule extraction (SMILE): principles and results.
8. Sachdev MS, Shetty R, Khamar P, et al. Safety and effectiveness of SILK using the ELITA femtosecond laser. Clin Ophthalmol. 2023.
9. Chen L, Khamar P, Wang Y, Fu H, Shetty R. Higher-order aberrations after SILK (ELITA). Clin Ophthalmol. 2024.
10. Reinstein DZ, Archer TJ, Randleman JB. Corneal biomechanics & preoperative selection in refractive surgery. J Refract Surg.
11. Sonmez B, Maloney RK. Central toxic keratopathy: description of a syndrome. Am J Ophthalmol. 2007. — CTK vs DLK grade IV status debated.
12. Linebarger EJ, Hardten DR, Lindstrom RL. Diffuse lamellar keratitis: diagnosis and management. J Cataract Refract Surg. 2000.
13. Flach AJ. Corneal melts associated with topical NSAIDs. Trans Am Ophthalmol Soc. 2001.