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Defining the Limits of Excimer Laser Surgery for Hyperopia
Accommodation in younger patients may result in undercorrection. Dermot McGrath reports
Despite significant improvement in visual outcomes driven by advances in laser technology in recent years, excimer laser-based hyperopia correction remains more difficult than myopia correction, especially for higher corrections, according to Jesper Hjortdal MD, PhD.
“There have been significant improvements in the safety, efficacy, stability, and accuracy of LASIK treatment for hyperopia and hyperopic astigmatism within the past two decades. However, it is clear accommodation in younger patients may result in differences in manifest and cycloplegic refraction resulting in apparent undercorrection,” he reported.
Looking at the evolution of excimer-laser-based correction for hyperopia over the years, Dr Hjortdal said such corrections are typically less forgiving than those for myopia due to the nature of the surgical procedure.
“For hyperopia, the surgeon has to remove more tissue in the periphery and the optical zone will not be as large as for myopic correction. This means that less correction can be obtained. The centration of the laser correction is also very important in hyperopic corrections due to the smaller optical zone,” he said.
Although photorefractive keratectomy (PRK) is a viable option for hyperopic treatments, Dr Hjortdal said LASIK has steadily become the laser treatment of choice over the years.
“LASIK is attractive to patients because there is no pain compared to PRK, and the visual recovery is rapid with good postoperative vision on day one after surgery,” he said.
In terms of which procedure delivers better outcomes in hyperopic patients, Dr Hjortdal said a Cochrane study that addressed the question in 2012 found a lack of randomised controlled trials precluded any firm conclusions, but the nonrandomised trials appeared to agree both treatment approaches offered comparable efficacy.
Some interesting results were also reported in a recent single centre, retrospective, non-comparative study on hyperopic LASIK on 379 eyes treated with LASIK for hyperopia and hyperopic astigmatism.i
“The authors also included a meta-analysis of 28 published studies [dating] back to 1998. Of the small number of patients over +3.0 D treated, there was a clear tendency for undercorrection. And [fewer] patients obtained 20/20 uncorrected distance visual acuity and experienced greater loss of lines of vision. Overall, the results were better for patients treated after 2005, undoubtedly due to improvements in excimer laser technology and larger treatment zones after that period,” he said.
Excimer laser treatment may also be an option for select cases of hyperopia in children, Dr Hjortdal said. He cited the Eustis [et al] study in which simultaneous PRK and strabismus surgery was deemed safe and effective in treating accommodative esotropia.ii Another study by Kulikova [et al] reported FS-LASIK effective in children with hyperopia and anisometropic amblyopia when traditional methods failed.iii
Dr Hjortdal said his personal preference is to recommend correction of hyperopia with excimer laser up to +4.0 D of spherical equivalent refraction.
“Using femtosecond-LASIK is probably preferable to surface ablation techniques and time will show whether SMILE for hyperopia becomes a safe, efficient, and accurate surgical technique,” he concluded.
This presentation was made at the 39th Congress of the ESCRS in Amsterdam.
i Moshirfar M et al, Ophthalmology and Therapy, vol. 10, 3 (2021): 547–563. ii Eustis et al, Am J Ophthalmol. 2018 Mar; 187: 125–129. iii Kulikova et al, J Refract Surg. 2020 Jun 1; 36(6): 366–373.
Jesper Hjortdal MD, PhD, is a consultant and clinical professor of ophthalmology at Aarhus University Hospital in Denmark and medical director of the Danish Cornea Bank. jesper. hjortdal@dadlnet.dk
