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Femtosecond laser-assisted intrastromal corneal ring segment implantation in keratoconus

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Session Details

Session Title: Refractive Corneal Surgery

Session Date/Time: Wednesday 17/09/2014 | 08:00-09:30

Paper Time: 08:12

Venue: Boulevard A

First Author: : D.Gore UK

Co Author(s): :    B. Allan              

Abstract Details


To report 18-month results of femtosecond laser-assisted intrastromal corneal ring segment (KeraRing) implantation in keratoconus.


Moorfields Eye Hospital


Design: Retrospective, uncontrolled case series. Inclusion criteria: Stage 2 or 3 keratoconus with CDVA ≤ 6/9 and contact lens intolerance. We excluded eyes with a minimum central corneal thickness < 350µm and/or thickness at the channel site < 450 µm. Surgical plans based on Scheimpflug tomography and subjective refraction were obtained from the manufacturer (Mediphacos Ltd,
 Belo Horizonte, Brazil). A 360-degree femtosecond laser channel was created at a depth of 400 µm (internal diameter 5mm, external diameter 5.9mm), into which either 1 or 2 ring segments were implanted. No sutures were used. Serial tomography and subjective refractions were performed to monitor for post-implantation ectasia progression. The main outcome measure was CDVA. Snellen visual acuity was decimalised for statistical analysis.


KeraRings were implanted in 17 eyes of 17 patients. The mean age (± standard deviation) was 32 ± 6 years. The mean follow-up was 20 ± 3 months. CDVA improved from 0.56 ± 0.22 pre-operatively to 0.79 ± 0.26 post-operatively (p<0.001), with a mean improvement of 2 Snellen lines of acuity. UDVA improved from 0.07 ± 0.05 pre-operatively to 0.3 ± 0.26D post-operatively (p=0.018). No eye lost vision following KeraRing implantation. Mean refractive astigmatism reduced from -7.88 ± 2.55D pre-operatively to -4.18 ± 1.97D (p<0.001). Mean spherical equivalent halved from -3.62 ± 3.46D to -1.85 ± 3.14D post-operatively (p=0.046). 5 (29%) eyes previously intolerant of rigid gas permeable contact lenses were comfortable in toric soft contact lenses post-operatively. No intra- or post-operative complications occurred. Central striae developed in one eye; despite achieving 6/9 CDVA, the patient elected to undergo deep anterior lamellar keratoplasty. Corneal collagen cross-linking was performed on four (24%) eyes for progressive keratoconus post-implantation.


Significant gains in vision can be achieved with femtosecond laser-assisted intrastromal corneal ring implantation in keratoconus. By improving CDVA and/or contact lens tolerability, keratoplasty may be avoided in these patients.

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