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D. P. Pinero, J. Alio, R. Barraquer, R. Michael; Predictive Model for the Visual Outcome After Keraring Implantation in Keratoconus Considering Corneal Biomechanics. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4633.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate by means of the Ocular Response Analyzer (ORA) the biomechanical changes after intracorneal ring segment (ICRS) implantation and to develop a predicting model for the postoperative visual outcome considering these biomechanical changes.
A total of 45 consecutive keratoconic eyes of 35 patients ranging in age from 18 to 55 years and implanted with ICRS were included. All cases were implanted with KeraRing using the femtosecond laser technology. Visual acuity, refraction, corneal topography and aberrations were evaluated during a 6-month follow-up. Additionally, corneal biomechanical changes were also evaluated with the ORA system.
No significant changes in corneal hysteresis (CH) and corneal resistance factor (CRF) were observed at 1 month postoperatively (p≥0.34). However, posterior changes in these parameters were detected (CH, 3 months, p=0.01). Significant correlations of the 1-month postoperative corrected distance visual acuity (CDVA) with keratometry (r=0.71, p<0.01) and also with corneal higher order aberrations (r=0.61, p=0.01) were found, but these correlations were lost during the follow-up. Multiple regression analysis revealed that CDVA at 1 month after surgery was significantly correlated with the preoperative mean keratometry and the preoperative difference between CH and CRF (p<0.01, adjusted R2 of 0.68). A less predictable model was found for the 6-month CDVA.
Biomechanical parameters measured with the ORA and mean keratometry are factors allowing a prediction of the postoperative visual outcome in a short term after ICRS implantation in keratoconic eyes. In the long term, corneal biomechanical changes limit the ring segment effect.
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