Myopia alternative

An eye with intacs. Courtesy Beatrice Cochener MD, PhD Intrastromal corneal ring segments (Intacs®, Addition Technology, Inc.) offer a potentially compelling solution for patients with low amounts of myopia who are not suitable candidates for LASIK or other photoablative procedures, according to Eve Durbant MD, University Hospital Brest, France. “Intrastromal corneal rings have a legitimate place in the treatment of mild myopia for at-risk corneas. Their efficacy is satisfactory, they work best on virgin corneas, and they enable the possibility of a combined treatment strategy with corneal crosslinking (CXL) for ectasia or photorefractive keratectomy (PRK) and/or CXL for residual astigmatism,” she told delegates attending the French Implant and Refractive Surgery Association (SAFIR) annual meeting in Paris. “The ring segments present a number of advantages for these corneas deemed at risk for traditional photoablative refractive surgery. Their implantation is straightforward, there is no ablation of corneal tissue and they respect the asphericity of the central cornea. They are ideal for the correction of myopia in the range of -1.0D to -4.0D and the technique is reversible in the event of any problems arising,” she said. Dr Durbant presented the results of a study of 34 eyes of 19 patients with a mean age of 33 years (range: 24-57) who were implanted with ring segments for myopia, the majority (23 eyes) with myopia less than -3.0D. GOOD ALTERNATIVE Evaluations of corneal topography showed that 26 eyes (76 per cent) were considered normal, three were asymmetric, one showed inferior steepening, one had forme fruste keratoconus, and three had secondary ectasia. Corneal hysteresis measurements (Ocular Response Analyzer/ORA, Reichert Technologies) were normal in eight eyes, pathological in nine (26 per cent) and unknown in 16. GRADUAL IMPROVEMENT The visual acuity results at one year were satisfactory, said Dr Durbant, with a mean uncorrected visual acuity of 0.89 (SD=0.26) and a gradual improvement of acuity over the follow-up period. Additional surgery was required in three eyes (PRK) for correction of residual astigmatism and one eye (CXL) for ectasia, and five eyes received combined PRK/CXL treatments. Complications in the series included infection of the incision, haze, and hyperopic shift of more than 0.75D. Visual symptoms included monocular diplopia/deformations in five eyes, halos/glare in three, fluctuations in two, insufficient correction in one and dry eye in 10. Summing up, Dr Durbant said that the ring segments provide a good alternative to photoablative techniques with the attendant risk of induced keratoconus, and also to phakic implants which were more invasive for moderate myopia. Eve Durbant: eve.durbant@gmail.com