DIFFERENCE MAKER YAG laser vitreolysis treats floaters, a common complaint among eye patients, says ophthalmologist T. Hunter Newsom, MD, of Newsom Eye & Laser Center in Tampa and Sebring, Fla.

Many of today's eye surgeons are as skilled with the laser as they are with the scalpel, using a beam of light to pulverize floaters, create a channel within the eye to relieve intraocular pressure or treat diabetic macular edema. Here's a roundup of the latest laser platforms your surgeons can use to treat a host of eye ailments, starting with an oh-so-satisfying way to eliminate those pesky floaters.

1. YAG laser vitreolysis
Using a YAG laser on eye floaters that drift through a patient's field of vision is safe and largely effective. It's also, well, kinda fun. "Like playing a video game," says Chirag Shah, MD, MPH, a retina specialist at Ophthalmic Consultants of Boston (Mass.), as he describes tracing the tiny vapor clouds with the laser's aiming beam before pulling the trigger to blast them into oblivion. "Obviously, the stakes are much higher, but it's truly an enjoyable procedure to perform."

Floaters occur when vitreous gel separates from the retina to form large, circular shaped spots in the visual field. Dr. Shah co-authored a recent pilot study that was the first randomized control trial to assess the efficacy and safety of using a nano-pulsed YAG laser to eliminate Weiss ring floaters in the vitreous gel. In the study, 36 patients treated with the YAG laser experienced, on average, a 53% improvement in their symptoms. "But there was a broad range, meaning some patients weren't satisfied with the procedure," says Dr. Shah. Still, there was a clinically and statistically significant difference in floater reduction between patients who underwent the laser treatment, and those who did not.

Dr. Shah was encouraged by the study's findings, which, he says, demonstrate the promise of YAG laser vitreolysis. "Choos-ing patients who have reasonable expectations increases post-op satisfaction with the procedure," he says. "Some patients want vitrectomy results with the relatively low risk of YAG laser vitreolysis, and that's not possible. If you want a completely clear vitreous, you have to do a vitrectomy."

DO NO HARM Subthreshold micropulse lasers limit the amount of heat delivered to retinal tissue and eliminate nearly all of the risk associated with delicate eye procedures.

Inder Paul Singh, MD, an ophthalmologist at the Eye Centers of Racine and Kenosha, Wis., is effusive with his praise for Dr. Shah's research. "It's a landmark study for modern vitreolysis, because it's the only one that's been done using the new laser technology," he says. "The laser has changed, so the safety and efficacy of the procedure has improved."

Dr. Singh says the latest version of the SLT-YAG combination platform used to pulverize floaters features an LED light source, which lasts longer and produces less glare in the visual field than the older model's halogen light source. More importantly, says Dr. Singh, the aiming beam has changed from red to green. "Red light has a longer wavelength, meaning it gets absorbed in the red reflex of the light source," he says. "The green aiming beam is easier to see in the middle of the vitreous when you're training it on floaters."

Dr. Singh says potential future upgrades to the laser platform include pattern laser delivery, so surgeons can deliver 10 to 20 laser shots with a single squeeze of the trigger, in order to have a better chance of vaporizing floaters, and an integrated range finder to take the guesswork out of determining how far the floater is from the eye's lens and retina.

Surgeons are currently instructed to blast away if the floater is in focus and the retina is out of focus, and to hold their fire if they can see both clearly. "Those are clinical pearls, not an exact science," says Dr. Singh. "There's work being done to provide surgeons with specific measurements before they activate the laser."

2. Selective laser trabeculoplasty (SLT)
SLT is far from a new treatment to reduce intraocular pressure in glaucoma patients, but the laser is experiencing a bit of renaissance now that minimally invasive glaucoma surgery (MIG) is gaining traction, according to Dr. Singh, who says surgeons don't currently have an effective pre-op diagnostic tool to know where the resistance to the outflow of aqueous humor is located within the eye. He explains that the pathophysiology of glaucoma is different in each patient, meaning the natural draining of aqueous humor from the trabecular meshwork through Schlemm's canal and into a distal channel can be impeded at any of those locations. Plus, he points out, MIG devices are designed to work in different parts of the fluid outflow system.

His research has shown that patients who had first undergone SLT responded better to having a stent implanted to divert fluid around blockages in the trabecular meshwork. "SLT works primarily at the level of the trabecular meshwork," says Dr. Singh. "If it works, that's where the resistance to outflow is located. If it doesn't work, the resistance is distal to the meshwork."

SLT laser treatment is therefore developing into a way for surgeons to know pre-operatively where the resistance to aqueous humor outflow is located, says Dr. Singh. "There's new thinking of using SLT not only as a therapeutic treatment to bring down eye pressure," he says, "but also as potential first-line diagnostic tool, so surgeons can better decide which MIG device to implant or which procedure to perform."

SKILL SET Surgeons who regularly perform retinal laser procedures won't have a tough time adapting to YAG laser vitreolysis.

3. Retinal rejuvenation
This proprietary nanosecond laser treatment of early-stage age-related macular degeneration and diabetic macular edema (DME) has shown promise in Europe, but is not yet available stateside. The laser targets and stimulates cells in the retinal pigment epithelium (RPE) and Bruch's membrane to release enzymes that have been shown to repopulate the cells in those areas to improve the permeability of Bruch's membrane and reduce retinal pathologies, including age-related macular degeneration and macular edema, according to Dr. Singh. "The current data is so remarkable that some people don't believe the results," he says.

4. Subthreshold micropulse photocoagulation
"Subthreshold" is a broad term that refers to any low-power laser that does not yield a visible burn or damage to the eye's anatomy, says Peter A. Karth, MD, MBA, a vitreoretinal physician and surgeon at Oregon Eye Consultants in Eugene, Ore. He says the primary modern subthreshold applications involve the use of micropulse lasers — which deliver ultra-short bursts of energy — to treat diabetic macular edema (DME), edema from vein occlusions and central serous retinopathy, and to reduce intraocular eye pressure in patients with high intraocular pressure.

Dr. Karth says subthreshold lasers activate heat shock proteins, which reinvigorate cells in order to help them perform their processes better. During treatment of DME, the micropulse laser is used to activate cells that pump fluid out of the eye. During micropulse cyclophotocoagulation in glaucoma patients, the laser targets the ciliary body, causing it to produce less aqueous humor. He points out that the treatment's effects are often not dramatic or sufficient enough to stand alone. The treatments may be repeated periodically if they show initial efficacy.

Subthreshold lasers are non-damaging to eye anatomy, says Dr. Karth. "Nearly every other therapy we use — injections to treat DME and surgery to treat glaucoma — carry inherent risks," he says. "This is an ultra-low-risk laser modality that produces low to no pain, making it very comfortable for the patient."

Added clinical benefit
The latest laser procedures offer potentially significant improvements to patient care, says Dr. Karth. However, he says, laser therapies are not the panacea to treating eye disease. "You wouldn't perform a micropulse laser procedure on a raging diabetic with huge edema and leave them alone for 3 months," explains Dr. Karth. "These procedures work best as adjunct therapies to injections in patients with macular disease and to drops, or even surgery, in glaucoma patients."

He points to the speed and degree of effectiveness of current eye disease treatments as one of the main reasons for the lack of widespread adoption of therapeutic lasers. "When a month's worth of bevacizumab injections dramatically reduces macular thickness in patients with DME, you want to administer more injections," he says. "This obvious positive result reinforces that the therapy is working. You often don't get that same effect with subthreshold lasers, although the data show the technology is effective."

Still, he believes therapeutic lasers can optimize the treatment of various eye conditions. Ideally, says Dr. Karth, "Lasers should be used to achieve better clinical outcomes, while reducing the burden of other riskier interventions." OSM