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Concurrent PRK, cross-linking improve vision after intrastromal ring insertion
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Simultaneous wavefront-guided PRK and corneal collagen cross-linking for keratoconus improved visual function after previous intrastromal corneal ring segment implantation, a study found.
“[We] believe that the triple therapy has the potential to postpone penetrating or lamellar keratoplasty in patients with the visually disabling disease of moderate keratoconus who are contact lens intolerant,” the study authors said.
The retrospective interventional case series included 45 eyes of 40 patients with moderate keratoconus and a mean age of 33.3 years. All patients had undergone Intacs intrastromal corneal ring segment implantation (Addition Technology) at least 6 months before simultaneous wavefront-guided PRK and corneal collagen cross-linking.
Uncorrected and corrected distance visual acuity, sphere, keratometry, pachymetry, corneal resistance factor and corneal hysteresis were assessed preoperatively and 3, 6 and 12 months postoperatively.
At 12 months, mean decimal uncorrected distance visual acuity improved from 0.2 to 0.55; the gain was statistically significant (P < .01). Mean corrected distance visual acuity improved significantly, from 0.58 to 0.77 (P = .01).
Mean cylinder decreased from –3.6 D to –1.3 D (P < .001).
Mean subjective sphere diminished from –0.49 D to +0.18 D at 12 months; the decrease was not statistically significant. However, mean subjective cylinder decreased significantly after treatment (P < .001).
Mean maximum and minimum keratometry values decreased significantly by 12 months (P = .03 and P = .01, respectively).
Changes in mean pachymetry, corneal hysteresis, corneal resistance factor and endothelial cell density were not significant.
No patients lost lines of corrected distance visual acuity. Haze was identified in 11.1% of eyes at 12 months.
Perspective
Back to TopGeorge D. Kymionis, MD, PhD
Several adjuvant procedures (eg, intracorneal ring segment implantation, topography-guided PRK), in combination with corneal collagen cross-linking, have been proposed to both improve vision of keratoconic patients as well as halt progression of their disorder. In their study, Kremer et al reported a significant improvement in apex keratometry and both uncorrected visual acuity and corrected visual acuity of keratoconic patients after ICR segment implantation followed by simultaneous wavefront-guided PRK and cross-linking. This triple therapy seems to be safe and effective for stabilizing keratoconus and improving keratometry and visual function of keratoconic patients. Although the authors used wavefront-guided instead of topography-guided technology, they did not evaluate postoperative wavefront aberrations; the lack of postoperative wavefront analysis is a limitation of this retrospective study. Nevertheless, in my opinion, this triple therapy seems to be a promising combined treatment; further clinical studies are needed to confirm its effectiveness and safety.
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