This paper describes the combined use of intracorneal ring segment implantation (ICRS), phototherapeutic keratectomy (PTK) and corneal collagen cross-linking (CXL) in patients with keratoconus.
Study design
Researchers retrospectively evaluated the outcomes of 55 eyes with progressive keratoconus that underwent a triple procedure of ICRS implantation, followed by PTK and then CXL. Patients were followed for 6 months. The researchers analyzed UDVA, CDVA, sphere, cylinder, mean spherical equivalent, index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, index of height asymmetry and index of height decentration. Secondary outcomes included total higher-order aberrations (HOAs), coma, spherical aberration, secondary astigmatism and trefoil.
Outcomes
There was a statistically significant improvement from baseline in UDVA, CDVA, sphere and cylinder 6 months after surgery (P<0.001). UDVA improved in 14% of the eyes to 20/25 and 96% had at least 20/40 or better CDVA; 30.9% of the eyes were within 0.5 D, 45.5% of the eyes were within 1.0 D, and 74.5% of the eyes were within 2.0 D.
For CDVA, 1 eye (2%) lost 3 lines (but gained UDVA), 11% lost 1 line, 38% showed no change and 49% gained between 1 and 8 lines of vision. Eighty-eight percent of the eyes had at least 1 line of improvement in UDVA , 79% improved by 2 lines or more, and 69% improved by 3 lines or more. Statistically significant improvements in total HOA, coma, spherical aberration, and secondary astigmatism were seen in addition to significant improvements in other keratometric endpoints, including index of surface variance, index of vertical asymmetry, keratoconus index, index of height asymmetry and index of height decentration.
Limitations
The specific inclusion criteria for progressive keratoconus were not specified. Though there was a statistically significant improvement in CDVA compared with baseline, the mean magnitude was small (−0.08 logMAR). This study does not evaluate long term outcomes or stability achieved from this combined procedure, as patients were only followed for 6 months.
Clinical significance
The combined procedure of ICRS implantation, PTK and CXL appears effective in reducing corneal aberrations and keratoconus indices and either stabilizing or improving visual acuity through 6 months in most patients with moderate keratoconus.