Effect of intrastromal corneal ring segment shift on clinical outcome: one year results for low myopia

To evaluate the effect of intrastromal corneal ring segment (ICRS) shift on clinical outcome.

Chu Morvan Ophthalmology Service, Brest, France.

Forty-seven eyes with myopia from -1.0 to -5.0 diopters (D) had ICRS surgery according to United States Food and Drug Administration protocol using a 2-segment implant design. Visual acuity, refractive, videotopographic, and biomicroscopic results in eyes that did not have contact between segments (Group A, n = 26) and in eyes that did have contact (Group B, n = 21) were compared.

Soon after surgery, migration of and subsequent contact between the implant segments occurred in 21 eyes (45%). Contact between the inferior ends was most common, occurring in 19 eyes; in the remaining 2 eyes, the superior ends of the implant touched. Superior contact was associated with superficial channels, wound-healing problems, and ICRS explantation. No segment shift was observed after the first postoperative week. No significant differences in visual acuity, qualitative vision, or density of intrastromal deposits were noted between the 2 groups. However, at 6 months there was more induced with-the-rule cylinder in Group B (mean +1.3 D +/- 0.7 [SD]) than in Group A (mean +0.7 +/- 0.5 D). Astigmatism was clinically significant in only 3 cases at 3 months.

Induced cylinder remains a limitation of the ICRS procedure, and segment contact appears to influence the rate of induced cylinder. Overall, however, the ICRS procedure produces promising results. Research efforts are underway to address induced cylinder and channel deposits associated with ICRS surgery.