Intrastromal corneal ring segments (ICRs): three- and six months results

In the period from May 1997 to November 1998 twenty-one eyes of fifteen patients with sighted eyes received Intrastromal Corneal Ring Segments (ICRS) for the surgical treatment of low myopia. The mean pre-operative refraction was -3.0 diopters (D) ranging from -1.5 D to -4.1 D. Three months results showed that 44% of the treated eyes had an uncorrected visual acuity (UCVA) of 1.0 or better while 94% had an UCVA of 0.5 or better. In 94% the postoperative refraction was within one diopter (D) of emmetropia and in 61% within 0.5 D of emmetropia. Mean induced astigmatism was 1.03 (std 0.75). The best spectacle corrected visual acuity (BSC VA) after 3 months was 1.0 or better in all patients. After six months the UCVA was 1.0 or better in 43% of the treated eyes while in 100% the UCVA was 0.5 or better. The post-operative refraction was within 1 D of emmetropia in 100% and within 0.5 D of emmetropia in 81%. Mean induced astigmatism was 1.00 (std 0.50). BSCVA was in 88% 1.0 or better and in 100% 0.9 or better. In one patient vascular ingrowth occurred due to a ring segment located under the incision. Three patients experienced a lower UCVA due to postoperative astigmatism. In only one patient in this series the ICRS were removed because of induced astigmatism. These preliminary results show that the ICRS seem to offer a safe, stable and reproducible method to correct low myopia. The operation carries a low risk but care must been taken to insert the ICRS as central as possible to prevent postoperative astigmatism.