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Keratoconus with high asphericity: correction with 300º Ferrara type intracorneal segments

Poster Details

First Author: L.Fernández-Vega Cueto-Felgueroso SPAIN

Co Author(s):    C. Lisa   B. Alfonso-Bartolozzi   J. Alfonso              

Abstract Details


Assess the efficacy and safety of the 300º arc Ferrara segments in the correction of keratoconus with high asphericity.


Instituto Universitario Fernandez-Vega, Oviedo, Spain


Forty-two eyes of 37 patients with a minimum follow-up time of 3 months, who presented Amsler-Krumeich grade II and III keratoconus with mean keratometry (k) greater than 48 diopters, an asphericity of less than -1.25 at 4,5 mm and less than -1.00 at 8.0 mm, and a central regular or irregular topographic pattern (<1.25) were included. The parameters evaluated were visual acuity with and without distance correction (CDVA and UDVA, respectively), mean k, asphericity at 4.5 and 8.0 mm, and coma.


The safety index obtained with this technique was 1.26. In addition, the use of 300º arc rings in these cases improves Ks and asphericity, reduces coma and improves CDVA. The mean k went from 51.24±2.89 preoperatively to 47.60±2.81 after implantation. The mean asphericity at 8.0 mm went from -1.54±0.52 preoperatively to -0.66±0.68 postoperatively. The coma was reduced from 1.57±0.68 to 1.06±0.42. The improvement of these three parameters produced an improvement in the DCVA of 0.51±0.19 to 0.64±0.15, making 64% of the operated patients to gain at least one line of vision.


The use of 300º arc segments at the 5 mm optic zone and 200 microns height in patients with Amsler-Krumeich grade II and III keratoconus is a recommended therapeutic procedure.

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