Effectively addressing presbyopia may require a rethink of the mechanisms leading to loss of accommodative ability.
According to Mitchell A. Jackson, MD, a growing body of evidence suggests that models of accommodative ability focusing solely on movement of the ciliary body may be incomplete. Indeed, stiffening of the sclera in an aging eye and other extralenticular processes appear to be a major component in why patients lose the ability to focus at near as they age.
“The problem is there's cross-linking in the sclera, and it stops moving,” Dr. Jackson told Dr. Singh during a recent episode of IJC.
A novel treatment approach, known as laser scleral microporation (LSM), seeks to address presbyopia at its fundamental root cause. LSM describes a procedure in which an Er:YAG laser (VisioLite, Ace Vision Group) is used to create a diamond-shaped matrix of transconjunctival scleral micropores in four oblique quadrants (Figure 1). The procedure is performed bilaterally, and the goal is to un-crosslink the sclera.
Figure 1. The LSM procedure is performed bilaterally, with the goal of un-crosslinking the sclera to allow a more complete dynamic range of focus across distance, intermediate, and near.
“By weakening the sclera, we get everything moving again, so we actually restore our dynamic range of focus versus our true accommodation,” Dr. Jackson said.
Study Data
A recent study evaluated the dynamic range of focus at 24 months after bilateral treatments of LSM in 50 patients (average age = 52.6 years).1 The primary outcome was visual performance as assessed with ETDRS logMAR charts at distance, 60 cm, and 40 cm after 24 months.
In the study, no patient lost distance vision, intermediate vision was unchanged, and binocular distance-corrected near visual acuity had improved significantly by 24 months compared to baseline (Figure 2). “It's pretty amazing. It stays effective for at least 2 years, and it's at a level that matches anything we do with a premium lens and/or presbyopia eye drop that's been approved in the United States,” Dr. Jackson said.
Figure 2. Visual outcomes at 24 months in 50 patients who received a LSM procedure.
As for the safety of the procedure with the current-generation laser (VisioLite, Ace Vision Group), moderate conjunctival vascularization and conjunctival edema may be evident on day 1 postoperatively, but these generally subside by week 1 (Figure 3). “This is really cosmetically acceptable. Eyes are white. Most patients are reading 20/40 or better uncorrected for near vision at day 1,” Dr. Jackson said.
Figure 3. Postoperative course of a sample patient who underwent LSM.
Inclusion criteria for the study may offer some clues for patient selection, as patients were required to be using a reading add of at least 150+.
“You want people who are already in reading adds full-time and they're miserable,” Dr. Jackson explained. “I always call it the ‘LASIK-to-lens procedure.’ Most of the patients who undergo LSM are refractively oriented: they’ve had LASIK or whatever procedure to fix their distance, or if they're just an emmetrope, naturally born that way—what are you going to do until they get a cataract? You don't want to rush to intraocular surgery too soon in some of these patients, it might be a higher risk. With LSM, we have the perfect presbyopic or age-related treatment from that LASIK-to-lens procedure.”
While data collection is ongoing with the study, Dr. Jackson pointed out that Ace Vision Group is currently conducting trials with a next-generation laser that is coupled with an OCT device for even greater accuracy in achieving the desired scleral depth. The company is aiming to pursue a 510(k) approval for use of the next-generation laser in the United States.
1. Ang et al. Dynamic Range Of Focus Recovery In Emmetropic Presbyopes After Laser Scleral Microporation: 24 Month Pilot Study Outcomes. Presented at: European Society of Cataract and Refractive Surgeons annual conference. September 8-12, 2023. Vienna, Austria.
