Therapeutic PTK

Wavefront-guided transepithelial PTK effective for stromal irregularities

Dermot McGrath

Posted: Friday, May 1, 2020

Michiel Luger MD

Corneal wavefront-guided transepithelial phototherapeutic keratectomy (TPTK) offers surgeons a safe and effective means to correct anterior stromal irregularities and achieve visual rehabilitation in eyes that have suffered loss of vision after a corneal event, according to a study presented at the 37th Congress of the ESCRS in Paris, France.

“We think wavefront-guided TPTK is a nice and elegant procedure for visual rehabilitation in cases of anterior stromal irregularities, including anterior stromal scars, or irregularities after refractive surgery such as LASIK and SMILE, or post-radial keratotomy,” said Michiel Luger MD.

“It is important, however, that the PTK phase of the treatment matches or exceeds the depth of the epithelial masking so as to get into healthy stroma, and that the residual stromal bed thickness is respected,” he added.

The cornea typically heals after anterior damage by regrowing and filling the gap with epithelium noted Dr Luger, Medical Director, Bergman Refractive Surgery, Naarden, the Netherlands.

“It creates an epithelium mask for the underlying irregularity but often leaves the patient with distorted vision. For these cases, we assess the patient, measure the corneal wavefront, pachymetry and epithelial thickness pattern and obtain the refraction error. Based on those elements, we calculate the ablation profile to erase the irregularity, correct the wavefront error and end up with healthy stromal tissue and improved vision,” he said.

Dr Luger presented a series of case studies to highlight the viability of the method. The first case was a young male patient with a corneal ulcer in his left eye after SMILE®.

“He had severe haloes and glare and other visual symptoms. The stromal tissue overlying the ulcer was completely melted away and filled with epithelium. The corneal wavefront preoperatively showed higher order aberrations, so we treated him with transepithelial PRK with the addition of sufficient PTK to end up with a clear and healthy stroma. After three months he had improved visual acuity and he was very happy with the big improvement in side-effects,” he said.

Dr Luger’s second case was a postradial keratotomy female patient who had presented for cataract surgery. “When we examined her, she had a very high refractive cylinder and a lot of coma and spherical aberration on the wavefront and irregular topography. We thought it was a better idea in this instance to treat the cornea first and then see if we had to do the cataract surgery as well. After transepithelial wavefront-guided PRK she ended up with very functional uncorrected vision with very low myopia and a big improvement in her corneal aberrations. Her vision was that good that she postponed the cataract surgery,” he said.

Dr Luger’s final case study was a patient with irregular astigmatism post-SMILE with an over-correction in his left eye and high levels of coma and spherical aberration. After treatment of transepithelial wavefront-guided PRK including PTK he ended up with a good visual outcome and an almost total reduction of corneal aberrations.

Dr Luger reported a total of three cases showing very satisfactory outcomes, and continues to refine the technique to further increase the success of this approach.