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J. F. Alfonso, D. Madrid-Costa, A. Poo-Lopez, R. Montés-Micó, J. Merayo-Lloves; New Nomogram for PMMA Ring-Segments Implantation for Astigmatism Correction in Keratonic Eyes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4968.
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© ARVO (1962-2015); The Authors (2016-present)
Outcome analysis of the efficacy, safety and predictability of a new nomogram for Ferrara PMMA ring-segments (Ferrararing, Boecillo, Spain and Keraring, Belo Horizonte, Brasil) implantation for astigmatism correction in keratonic eyes.
Charts form 119 keratoconic eyes that had sequential implantation of the PMMA ring-segments following this new nomogram were retrospectivily evaluated. According to this nomogram the choice of segment arc-length based on cylinder and the segment thickness dependent on corneal pachimetry and keratometry. Uncorrected distance visual acuity (UCVA), best corrected distance visual acuity (BCVA), uncorrected distance near visual acuity (UCNVA), best distance-corrected near visual acuity (BCNVA) and residual refractive errors analyzed using vector analysis were recorded at 6 months post-KeraRing ICRS implantation.
The mean UCVA (Snellen decimal) changed from 0.21 ± 0.16 before surgery to 0.5 ± 0.29 six months after PMMA ring-segments implantation (P< 0.0001). The BCVA changed from 0.76 ± 0.16 before surgery to 0.85 ± 0.14 six months after PMMA ring-segments implantation (P< 0.0001). The efficacy index at 6 months of PMMA ring-segments implantation was 0.71. 90.75% of the eyes maintained or improved the BCVA at 6 months of surgery; the safety index at 6 months was 1.12. The mean cylinder changed from - 4.14 ± 1.85D preoperatively to -1.49 ± 0.96D 6 months after surgery (P< 0.0001). The preoperative astigmatism component (J0, J45) highly correlated the amount of change in the post-PMMA ring-segments implantation astigmatism component (J0, J45) (R= 0.67 and R= 0.86, for J0 and J45, respectively).
This nomogram for PMMA ring-segments implantation was safe, effective and predictable for astigmatism correction in keratoconic eyes.
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