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Topography-guided PRK (TG-PRK) with simultaneous collagen crosslinking (CXL) shows promise as an effective treatment for patients who are highly symptomatic because of postLASIK ectasia.
Vancouver-Early results using two excimer laser platforms show topography-guided PRK (TG-PRK) with simultaneous collagen crosslinking (CXL) has promise as an effective treatment for patients who are highly symptomatic because of postLASIK ectasia, said Simon P. Holland, MD.
Dr. Holland, clinical professor of ophthalmology, University of British Columbia, Vancouver, reviewed outcomes for a series of 24 eyes with postLASIK ectasia; the TG-PRK procedure was performed using the Allegretto WaveLight laser (Alcon) in 17 eyes and with the iRES laser (iVIS) in seven eyes. All of the eyes had follow-up of at least 6 months.
“All but two patients [had symptomatic improvement], two-thirds of eyes achieved UCVA of 20/40 or better, and close to half of the eyes gained 2 or more lines of BCVA. Mean astigmatism was reduced from –3.3 to –1.1 D in the Allegretto-treated eyes and from –2.5 to –1.1 D after iRES treatment,” Dr. Holland said.
“With follow-up to 3 years in some eyes, we have seen no progression of ectasia,” he added.
Comparing the two laser subgroups, Dr. Holland observed that the iRES treatment does not induce as much myopia as the Allegretto system because the iRES ablation is more central. However, the gain in BCVA is less with the iRES treatment. While 53% of eyes in the Allegretto group gained 2 or more lines of BCVA, only 14% of the iRES-treated eyes achieved that level of improvement. No iRES-treated eyes and 1 (6%) Allegretto-treated eye lost 2 or more lines of BCVA.
CXL was performed with application of 0.1% riboflavin in dextran until aqueous staining. Hypotonic dextran was used to thicken the cornea in eyes with thickness <400 µm. The UV irradiation was with a 370-nm light source at 3 mW/cm2. The excimer laser portion of the procedure was performed with transepithelial PRK and a custom topographical neutralization technique.
Postoperative management consisted of a bandage contact lens and a standard postPRK protocol.
“Delayed epithelialization remains the main complication of this procedure,” Dr. Holland said.
Dr. Holland and his collaborator, David T.C. Lin, MD, have no financial interest in the material presented. This article is based upon material presented by Dr. Holland at Refractive Surgery 2012 during the annual meeting of the American Academy of Ophthalmology.
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