This article is more than 5 years old. Information may no longer be current.
Transepithelial phototherapeutic keratectomy during corneal collagen cross-linking boosts visual outcomes
The combined procedure yielded statistically significant improvements in distance visual acuity, corneal astigmatism and steep keratometric values.
Click Here to Manage Email Alerts
Corneal collagen cross-linking combined with transepithelial phototherapeutic keratectomy yielded better visual and refractive outcomes than when performed with mechanical epithelial debridement, a study found.
The combined procedure also halted the progression of keratoconus for 1 year, the study authors said.
“The question so far was, and still is, if we have to remove the epithelium or not during CXL. Our study seems to answer this question in a different way: The epithelium has to be ablated using excimer laser [transepithelial phototherapeutic keratectomy] during CXL,” George D. Kymionis, MD, PhD, the corresponding study author, said in an email interview.
Cross-linking combined with transepithelial phototherapeutic keratectomy (t-PTK) is particularly suited for thin corneas, Kymionis said.
“We believe that this actually new combined technique should be performed in any case of CXL for better visual and refractive results, especially in cases in which photorefractive keratectomy before CXL cannot be performed due to low corneal thickness,” he said.
The study was published in Ophthalmology.
Study design and methods
The prospective study included 38 eyes of 34 patients with a mean age of 28 years and progressive keratoconus who underwent corneal collagen cross-linking. Sixteen patients underwent cross-linking with t-PTK; 18 patients underwent cross-linking with mechanical epithelial debridement using a rotating brush.
“Patient selection was a difficult but very significant part of the study,” Kymionis said. “Our study was a prospective, comparative analysis of well-matched groups. All eyes of both groups matched the inclusion criteria, and both groups were optimally matched before statistical analysis. There were no significant differences found between the two groups preoperatively for any of the parameters evaluated after statistical examination.”
Visual and refractive outcomes and corneal confocal microscopy were evaluated preoperatively and at 1, 3, 6 and 12 months after surgery.
Results and conclusions
Study results showed that in the t-PTK group, mean logMAR uncorrected distance visual acuity (UDVA) improved from 0.99 preoperatively to 0.63 at 12 months. The improvement was statistically significant (P = .02).
Mean corrected distance visual acuity (CDVA) improved from 0.3 preoperatively to 0.19 at 12 months. The improvement was significant (P = .008). Improvements in CDVA at 1, 3 and 6 months were not statistically significant.
“T-PTK-CXL resulted not only in better visual and refractive outcomes but also in improved steep keratometric values — areas with thinner epithelium — and corneal astigmatism,” Kymionis said.
Improvement in mean steep keratometry readings reached statistical significance at 12 months (P = .001). However, flat keratometry readings did not change significantly.
Mean corneal astigmatism improved from –5.84 D preoperatively to –4.31 D at final follow-up (P = .015).
In the mechanical debridement group, UDVA, CDVA and corneal astigmatism improved insignificantly at 12 months. However, improvement in UDVA approached statistical significance at 6 months (P = .06) and 12 months (P = .054), Kymionis said.
“A possible explanation for this could be the small number of patients enrolled. Another reason could be the 1-year follow-up,” he said. “Longer follow-up of the same patient group could reveal statistically significant improvement in visual acuity due to the long-term effect of the CXL procedure.”
There were no reported intraoperative or postoperative complications or changes in endothelial cell density in either group, the authors said. – by Matt Hasson