Expanding the Limits of KLEx

The potential applications of keratorefractive lenticule extraction (KLEx) are expanding for refractive corrections of all types, including hyperopia, according to Sri Ganesh.

“Commercial software has been limited to myopia and myopic astigmatism, and hyperopic software has just been introduced,” Dr Ganesh said. Mixed astigmatism correction is in the works and may soon follow, as may wavefront and topography guided KLEx, he added.

Current commercial CE limits on KLEx for myopia are -1.00 D to -10.00 D with up to -5.00 D astigmatism and -12.00 D spherical equivalent. For hyperopia, commercial corrections are available for up to +6.00 D with up to +5.00 D astigmatism and up to +7.00 spherical equivalent in hyperopic meridian.

Myopia

Dr Ganesh has had success with KLEx across the myopic range, including for low myopia. “For low myopia, there is some consensus that KLEx might not work as well, and PRK might be better.”

However, a study Dr Ganesh and colleagues conducted found better quality of vision, including better contrast sensitivity, and greater patient satisfaction due to better postoperative comfort among low myopia KLEx patients three months after surgery.

Pushing the commercial limit for high myopia, Dr Ganesh reported a case of -10.00 D with -1.75 D astigmatism correcting to 0.00 D sphere and -0.50 D astigmatism, and uncorrected distance vision of 6/5.

He has even had success with very high myopia using research software. For example, a patient with -15.00 D sphere and -3.50 D cylinder was corrected to -0.50 D sphere and -1.25 D cylinder with UDVA of 6/9. “It’s possible to treat very high myopia, but commercially, it’s not available.”

Yet Dr Ganesh said very high myopia may be corrected by combining a phakic intraocular lens with KLEx. A study of 12 eyes in 7 patients undergoing combined phakic implant and KLEx with a mean preoperative -23.30 D ultimately resulted in gains of two to four lines of corrected distance visual acuity in all eyes.

Astigmatism

High myopic astigmatism is also treatable with KLEx, Dr Ganesh added. He emphasised the need to adjust for cyclotorsion in correcting myopic astigmatism, especially those with a higher cylinder.

Mixed astigmatism is another question because it is not currently available with commercial software. Even so, Dr Ganesh has done it with research software with good results. The procedure involves correcting the astigmatism first, followed by the hyperopia. He published a series of 13 mixed astigmatism eyes, in which 92% reached UDVA of 6/9.5 and 54% reached 6/6 or better after KLEx correction.

“Hopefully, we will have the commercial software in the near future.”

Hyperopia

Hyperopia corrections are possible with newly CE-marked software, Dr Ganesh said. “The results are quite similar to LASIK, but the long-term stability is better,” he said of the global registration study for hyperopic KLEx.

“I have treated hyperopia from the age group of 18 to 60 years. The ideal amount of hyperopia where we get good results is up to 4.50 D, but you can treat up to 6.00 D and a spherical equivalent of 7.00 D,” he told EuroTimes. “In higher corrections for hyperopia, you can expect some regression and induction of higher-order aberrations which can potentially reduce the BCVA (similar to hyperopic LASIK).”

Dr Ganesh spoke at the 2024 ESCRS Congress in Barcelona.

Sri Ganesh MBBS, MS, DNB, DSC(Hon), FR CS(Glasg), FWCRS is chairman and managing director of Nethradhama Hospitals in Bangalore, India.