Advanced keratoconus with very low pachymetry – Can contact lens avoid corneal surgery?

Abstract

Clinical relevance: Keratoconic eyes with low pachymetric values, precluding safe CXL can show significant improvement in vision with newer scleral Contact lenses(CL), which was not possible with older rigid CLs. Purpose: To describe diagnostic and management difficulties in keratoconic eyes with pachymetry too low for CXL (Collagen Cross linking)necessitating surgery for improving tensile strength, yet having significant improvement in vision with newer rigid contact lenses such that immediate keratoplasty can be deferred. Methods: Case records of 16 patients (20 eyes) were reviewed. All patients had advanced keratoconus with low pachymetric values but had significant improvement in vision with rigid CLs. CXL was not safely feasible in these eyes and immediate surgical treatment for tissue strengthening was deferred as they had good vision with newer rigid CLs. Patients were kept under close observation due to the risk of developing corneal hydrops. Results: Mean age was 25.68 years. Mean best-corrected visual acuity with glasses was 0.54logMAR, whereas, with rigid CLs was 0.18logMAR. Mean steep-keratometry (K) was 62.66D. Mean central pachymetry, highest posterior surface elevation, and pachymetry at thinnest location was 314.4, 119.6 and 313.61microns respectively. Mean follow-up was 4 years. Conclusion: Advanced keratoconic eyes may have pachymetric values too low for CXL, therefore needing keratoplasty for tissue strengthening and yet can have good vision with rigid CLs. Quantitative analysis of further progression of keratoconus in these eyes is difficult as imaging techniques become unreliable in advanced stages of the disease. Significant improvement in vision with newer rigid and scleral CLs makes the decision to operate, purely for tissue building, difficult.