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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.