Intracorneal ring segments followed by collagen cross-linking and PRK for treatment of keratoconus

A Iovieno, MD; ME Légaré, MD; DS Rootman, MD

Department of Ophthalmology – Toronto Western HospitalUniversity of Toronto

Authors have no financial interest

KeratoconusBilateral, non-symmetric and non-inflammatory

corneal ectasia often leading to progressive visual deterioration

At early stages visual defect can be managed with spectacles or contact lenses (CL), while advanced disease often requires intracorneal ring implantation, lamellar or penetrating keratoplasty

Corneal collagen cross-linking (CXL) is a recently developed technique that retards or halts the progression of keratoconus, with a minimal effect on visual acuity

Refractive surgery, with the exception of topographic-guided PRK treatments in selected cases, is contraindicated in patients with keratoconus

Raiskup-Wolf et al, 2008; Lin et al, 2008;

Combined proceduresCXL and intracorneal ring placement have been

successfully combined in previous studies

Superior results were obtained by performing corneal ring placement first followed by CXR

The association of CXL and topographic-guided PRK treatments has also shown interesting results

Performing PRK and CXL the same day was found to be more effective than sequential treatments

Coskunseven et al, 2009; Kymionis et al, 2009; Kanellopoulos 2007, 2009

Aim

Evaluate the effect of combining intrastromal ring implantation followed by same day CXL and PRK in patients with keratoconus

Methods4 patients/5 eyes (5 M, mean age: 45.25 range:

33-55) were included in our study

Inclusion criteria: progressive keratoconus (changes in refraction and/or corneal topography in the last 6 months), CL intolerance and central corneal thickness ≥ 450 μm

First, intracorneal stromal rings (Intacs©) placement was performed using a femtosecond laser (Intralase©).

Average time between Intacs© and CXL/PRK: 21 ± 8.6 months.

MethodsThen, patients underwent standard PRK and CXR

procedure on the same day

Undercorrection of the sphere and the cylinder was planned in order to minimize tissue ablation (< 50 μm)

Follow-up: 5.9 ± 2.4 months

Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), mean refractive spherical equivalent (MRSE), mean K, steepest K, were recorded at baseline, last follow-up before PRK/CXR, 3 months and 6 months after PRK/CXR.

Results

1.09 ± 0.25 vs - 0.44 ± 0.21 (p<0.01) -0.29 ± 0.19 vs – 0.02 ± 0.18 (p<0.05)

44.37± 2.75 vs 43.09 ± 3.06

47.58 ± 3.11 vs 44.97 ±3.26

MRSE and cylinder: good accuracy of PRK treatment

MRSE CYL

-1.9 ± 1.39 vs 0.31 ± 1.33 (p<0.05)

First visit After Intacs

After PRK/CXR

First visit After Intacs

After PRK/CXR

ConclusionsIntracorneal rings placement followed by same

day PRK/CXL has shown promising preliminary results in correction of keratoconus patients

The use of topographic-guided treatments (not available in our facility) may result in more predictable and accurate ablation patterns

Limited accessibility of corneal transplant (tissue availability) pushes towards newer strategies for vision rehabilitation in keratoconus

Longer follow-up and a larger number of patients are needed to confirm our data.