Analysing Laser Refractive Procedures

The ESCRS Eye Journal Club held a webinar hosted by Artemis Matsou MD and Alfredo Borgia MD, with guest experts Professor Sorcha Ní Dhubhghaill MD, PhD and Professor Riccardo Vinciguerra MD, to discuss the paper “Safety and efficacy of a laser refractive procedure in eyes with previous keratoplasty: systematic review and meta-analysis.”¹

Dr Borgia summarised the study, noting the authors performed a comprehensive systematic review of the online peer-reviewed literature regarding patients undergoing LASIK and PRK after DALK or penetrating keratoplasty. Using the Cochrane, MEDLINE, and EMBASE electronic databases, they identified 631 articles published between 1992 and 2022, of which 31 fit the eligibility criteria. The studies involved a total of 732 eyes of 683 patients.

The meta-analysis showed that among LASIK-treated eyes, the UCVA was 20/20 or better in 8% of eyes and 20/40 or better in 50%. In addition, the mean spherical equivalent was reduced by 4.00 D after conventional LASIK and 3.30 D after customized LASIK. Cylinder was also significantly reduced—by 3.16 D after conventional LASIK and -2.66 D after customised LASIK.

Among PRK-treated eyes, UCVA was 20/20 or better in around 9% of cases and 20/40 or better in 40% of cases. Mean spherical equivalent was reduced by 3.00 D after conventional PRK and 2.74 D after customised PRK, and mean cylinder was reduced by -1.95 D after customised PRK and -2.78 D after conventional PRK.

The overall complication rate was 14.3% and the rate was 17% for PRK and 11% for LASIK. The most common complications were corneal haze for PRK epithelial ingrowth for LASIK. The rate of graft rejection was 2.4% and that of perforation was 1.2%. Around 6% of cases lost more than two lines of corrected distance visual acuity.

Opening the discussion, Dr Matsou noted that over the 30-year span in which the studies were conducted, there have been significant changes in the laser platforms, ablation profiles, and treatment zones. She asked the panellists if they would have conducted the meta-analysis differently.

“I think perhaps a more elegant approach would be to subdivide the studies based on technique. But even that is flawed, because each generation technique is improved,” Prof Ní Dhubhghaill said. “But I think that at least would give the surgeon more relevant information on the laser they have access to.”

Prof Vinciguerra concurred—although he noted the more one sub-stratifies, the smaller number of patients will be available for analysis, compromising the statistical power of the study. In his view, the first problem in the study was the primary outcome criteria.

“For this meta-analysis, the main outcome was uncorrected distance visual acuity. Who is aiming for a high uncorrected distance visual acuity after penetrating keratoplasty? No one,” he said. “Therefore, the primary aim reported is not even the primary aim of the surgeon.”

Panellists discussed the study’s outcome reliability, particularly when considering the high heterogeneity of primary outcomes and the implications of including studies with sequential laser procedures. They also took issue with the study authors’ conclusion that the laser refractive procedures were safe.

“When you were rolling the dice with a 5.8% chance of reduction in vision, a 1.5% chance of perforating the graft… My feeling is safe is not the optimal word, although if you’re quickly reading the abstract, you might get this impression,” Prof Ní Dhubhghaill said.

Prof Vinciguerra noted while the complication rate would be unacceptable if the goal was enabling patients to see without glasses or contact lenses, it would be more acceptable if the goal was enabling patients to see with correction, especially if the patient was not able to see in any way preoperatively.

“If we are doing these therapeutic laser procedures for a patient [unable] to see even with glasses, then what you have to show in terms of main outcome is higher order aberration, corrected distance visual acuity, and that’s it,” he said. “Then the amount of complication you are showing is acceptable.”

Concluding the webinar, Dr Matsou asked the panellists if they had any advice for young ophthalmic surgeons when dealing with post-keratoplasty patients.

“My tip would be to trust your instincts,” Prof Ní Dhubhghaill advised. “If you really feel that this patient expects from you what is neither technically nor scientifically possible to guarantee, you really have to have the strength to say, ‘No, I’m going to advise you to do something else.’”

“My recommendation is if you have a patient like that, refer them to an expert with more experience in such cases, and if possible, come and see the treatment and how they did the surgery, and learn from it,” Prof Vinciguerra said.

Artemis Matsou MD, MRCP(UK), FEBO, PgDip CRS is Consultant Ophthalmologist and Cataract Lead at Queen Victoria Hospital, East Grinstead, United Kingdom. art.matsou@gmail.com

Alfredo Borgia MD, FEBO is based at Royal Liverpool and Broadgreen University Hospitals, Liverpool, United Kingdom. alfr.borgia@gmail.com

Riccardo Vinciguerra MD is based at the Humanitas San Pio X Hospital, Milan, Italy, as well as a research collaborator at Biochemical Engineering Group, University of Liverpool, United Kingdom. vinciguerra.riccardo@gmail.com

Sorcha Ní Dhubhghaill MBBCH, FEBOS-CR, PhD is Head of Department and Corneal and Cataract Specialist at UZ Brussels and Chair of Ophthalmology at the Vrije University of Brussels, Belgium. sorcha.ni.dhubhghaill@uzbrussel.be

1. H Alsubhi, et al. “Safety and efficacy of a laser refractive procedure in eyes with previous keratoplasty: systematic review and meta-analysis,” J Cataract Refract Surg, 2023 Dec 1; 49(12): 1275–1282.