[Intra-corneal rings for the correction of weak myopias]

Intra-stromal rings (ICR) represent a new method for low myopic correction. An indirect central flattening is induced by a peripheral steepening related to the segments. This surgery was recently approved in Europe, but is still under evaluation in the multicenter study controlled by the FDA (Food and Drug Administration). We took part in that protocol and report our results at one year follow-up.

Twenty-five patients were included in the study with 47 operated eyes and a follow-up between 3 to 18 months. Data relative to refractive results, quality of the vision and anatomic changes induced by intrastromal segments will be collected at the issue of a rigorous survey.

At one year, non-corrected visual acuity was 20/40 or better in 100% and 20/20 in 60%. We noted no loss in best visual acuity and an improvement of one or two lines in 20% of operated eyes. No significative changes were observed concerning: intraocular pressure, corneal sensitivity, central pachymetry or corneal endothelium. Three eyes had to be explanted and recovered the preoperative refraction. No severe complications were observed.

Analysis of results is in favor of the efficacy, predictability and reproductibility of the surgery, which might be better with rings of a diameter under 0.40 mm. Occurrence of postoperative astigmatism appears to constitute the main limit suggesting discussion on etiologic factors and modalities of treatment.

This concept of intra-corneal rings appears particularly promising for correction of low myopia and maybe in the near future for correction of others ametropia, requiring design of new specific segments. Essential interest of this surgery is the respect of the central area and its potential reversibility.