Manual mid-stromal dissection as a low risk procedure to stabilize mild to moderate progressive keratoconus

BACKGROUND: To evaluate the efficacy of manual mid-stromal dissection in stabilizing progressive keratoconus. METHODS: Surgeries were performed in 16 eyes of 14 patients with progressive keratoconus. All eyes were examined before and at 1 day, 1 week, 1, 3, 6 and 12 months after surgery, and every 6 months thereafter. Pentacam (simK, Kmax and pachymetry), best corrected visual acuity (BCVA) and subjective refraction were recorded up to the latest follow-up visit (mean follow-up time 6.6 ± 2.4 years). RESULTS: All surgeries were uneventful, and no postoperative complications occurred. Keratometry values (n = 15) stabilized in 6/11 eyes (55%) with a preoperative Kmax < 60.0 diopter (D), while all eyes > 60 D showed continued progression. In 11/15 eyes (73%) pachymetry was unchanged. BCVA with spectacles remained stable in 7/12 eyes (58%) and improved ≥2 Snellen lines in 5/12 eyes (42%). BCVA with a contact lens remained stable in 4/9 eyes (44%), improved ≥2 Snellen lines in 3/9 eyes (33%) and deteriorated in 2/9 eyes (22%). CONCLUSIONS: Manual mid-stromal dissection was effective in 50% of keratoconic corneas with Kmax values < 60 D and may be considered in cases ineligible for other interventions such as UV-crosslinking, stromal ring implantation or Bowman layer transplantation. An advantage of the procedure may be that the tissue is unaltered and that no synthetic or biological implant is required.