To Laser or not to Laser — A Glaucoma Primer and the Pros and Cons of Laser Surgery

To laser or not to laser, that really IS the question. There’s just so much information out there and so many different approaches for glaucoma patients of all types, including open-angle glaucoma and angle-closure glaucoma, that making the decision can feel a little like Hamlet’s famous dilemma. But hopefully that’s why you’ve joined us for this article today — to wade through the turbulent waters of laser eye surgery for glaucoma patients and sort out fact from fiction in terms of things like complications and side effects.

The good news is, sorting out your treatment options and deciding if laser treatment is the right glaucoma treatment for you doesn’t have to be like reading Shakespeare. We’ll break it down for you here into digestible bits and pieces, including a brief overview of glaucoma, the different treatment options, and finally the laser procedures involved to help guide you when you follow-up with your eye doctor about what’s right for you.

Glaucoma at a Glance

Before we get into what the heck to do about glaucoma, it might be of service to understand a little bit about what the heck glaucoma IS. The best way to think about glaucoma is as degeneration of the optic nerve. Well, who even cares about the optic nerve anyway, don’t we have nerves all over our body? Indeed we do, dear reader, indeed we do, but the optic nerve is a special nerve in ways that make things tricky.

Firstly, it’s best to think of the optic nerve like a cable that carries all of the information your eye picks up to be interpreted by your brain. It’s kind of like the cable that runs from your computer to your monitor. Think about it like this: When your monitor isn’t connected to your computer, you can’t really use it because you can’t see what’s going on. In the same way, if the optic nerve is damaged then there’s no signal between your eye and the brain, resulting in vision loss. So yeah, that’s one pretty dang important nerve.

But the body can fix itself, right? Well, the issue with the optic nerve, and what can make glaucoma so scary is that it is no ordinary garden-variety nerve. The optic nerve is a nerve of the central nervous system, and these nerves are different in that they can’t regenerate like other nerves.

But, the inquisitive reader may say: My ophthalmologist is always going on about eye pressure — what’s that got to do with anything? Well, though glaucoma is technically defined in ophthalmology as damage to the optic nerve, this damage is most commonly caused by a buildup of intraocular pressure (IOP) due to a buildup of fluid in the front part of the eye (called the anterior chamber in fancy ophthalmology talk). By the way, high IOP is also called ocular hypertension, but usually in contexts where glaucoma is not present, so if you hear someone use that term, don’t let it throw you.

Types of Glaucoma and a Crash Course on Intraocular Pressure

Before we hop into treatment options, it’s important to understand a touch more about the types of glaucoma and how IOP builds up in the first place. There are many types of glaucoma. The first and most common is primary open-angle glaucoma, a chronic and insidious slow-burner, which also happens to be the leading cause of blindness in the world after cataracts. The other is angle-closure glaucoma, which can be chronic, too, but also sudden and acute, and is an emergency when it strikes. In both of these types of glaucoma, eye pressure builds up because a fluid called the aqueous humor has limited options for outflow, much like a clogged pipe.

In open-angle glaucoma, a kind of drainage grate called the trabecular meshwork is blocked to a certain degree; that’s why this condition has a kind of damage-over-time effect. As the number of holes in the trabecular meshwork that get blocked increase with age and time, the disease progresses to advanced glaucoma and vision loss.

In angle-closure glaucoma, both the trabecular meshwork and the other outflow option for the aqueous humor, the so-called “angle” between cornea and iris, is blocked. This is obviously “bad news bears,” as a double blockage means no way to lower pressure in the eye.

Treatment Options NOT Involving Lasers

Treatment of these common types of glaucoma almost always consists of lowering the pressure in the eye. Yeah, it’s that simple — or at least, it SOUNDS that simple. In reality, this is no easy task, as pressure buildup can have lots of causes, and each eye is highly unique in terms of structure and susceptibility to certain side effects. There are just so many variables involved, like whether you wear contact lenses, your susceptibility to dry eye, the width of the iridocorneal angle, the country you live in and the whims of FDA approval, what you had for lunch that day (just kidding) … the point is that success rates and treatments vary greatly because humans vary greatly, and so treatments vary, too.

Your eye doctor will almost always start with medications or topical eye drops applied directly to the ocular surface which penetrate the eye via the corneal route or the sclera (white of the eye) as a first-line treatment. There are almost as many medications and eye drops as stars in the night sky (well, not quite that many), and with names that seem more word soup than anything else to the layman, like prostaglandin analog and rho kinase inhibitor, there’s no need to go into them in this article (you can find more on eye drops here).

Aside from eye drops, there are many surgical options for glaucoma patients that don’t involve lasers. The first one is actually good old cataract surgery. Research has shown that cataract surgery also reduces IOP / ocular hypertension, some surprisingly good news for folks with cataracts, who get some serious bang for their surgical procedure buck. Another involves making tiny incisions in the eye to create more outflow passageways, such as a trabeculectomy or sclerectomy. Another much newer group of procedures is called MIGS, or minimally invasive glaucoma surgery, where surgeons make smaller incisions or insert fancy doodads like shunts and stents to keep that river of aqueous humor flowing or to reduce the amount of liquid altogether. For more info on advancements in MIGS and other cutting-edge glaucoma technology, check out our write up on the 2020 OIS Glaucoma Innovation Showcase.

Laser Surgeries for Glaucoma and Weighing up the Pros and Cons

To Laser or not to Laser — A Glaucoma Primer and the Pros and Cons of Laser Surgery

So now that you’re all set on the basics, let’s finally turn our attention to surgical laser procedures and weigh up the pros and cons of each. Traditionally, ophthalmologists have always considered any kind of surgery, and especially laser surgery, as a backup plan when a patient doesn’t respond to more conservative treatments like eye drops or medications. Even today this bias against surgical procedures exists, but you will see soon that this might all be changing, and for good reason. We are going to cover the two most common laser procedures: laser trabeculoplasty for open-angle glaucoma, and iridotomy for angle-closure glaucoma

For Open-Angle Glaucoma: Laser Trabeculoplasty

Behind door number one is a procedure known as laser trabeculoplasty, which is used in open-angle glaucoma patients, as it deals primarily with the trabecular meshwork. Even though you probably can’t say it 5 times fast without tying your tongue into knots, you should be aware of it because it is by far the most common type of laser surgery for glaucoma and has been generating a lot of positive buzz in recent years. The idea is that a laser is used to poke tiny holes around the sclera and trabecular meshwork to increase the flow of aqueous humor and lower intraocular pressure. Back in the day, a procedure called argon laser trabeculoplasty (ALT) was used. It worked, but it ripped eyeballs to near shreds, and couldn’t be repeated when more pathways in the trabecular meshwork got plugged up as the disease progressed. No wonder doctors have long preferred more conservative options.

Enter selective laser trabeculoplasty (SLT), a much more gentle, modern and shall we say, refined, approach instead of the scorched earth, ripping and tearing and scarring approach of ALT,  SLT uses a lower power laser to punch smaller holes and work more closely with the delicate structures of the eye. SLT is an outpatient procedure with great outcomes, and can be repeated due to its relatively low cost and risk to the patient.

Because of these major improvements in SLT, it is also being intensively studied as first-line therapy for glaucoma over medications or eye drops. So before you take the dive, here are some advantages and disadvantages to consider.

Pros of SLT

  • Highly effective
  • Does not damage the eye heavily so can be repeated
  • Is a short, relatively cheap outpatient procedure
  • Reliably decreases IOP
  • Does not rely on patient compliance for efficacy — who ever REALLY remembers to put eye drops in or take their medications every day?
  • Can avoid certain side effects of conservative treatments, like dry eye
  • Improves psychological health — patient feels less “sick” when they don’t need to take meds or put in drops every day
  • Can be used in conjunction with other treatment options, like meds, eye drops, MIGS, and even iridotomy (see below) for angle-closure glaucoma for even better outcomes

Cons of SLT

  • Some conservative therapies are still more effective in some cases
  • Doesn’t carry risk of postoperative pressure spike, which could be disastrous
  • Not applicable to less-common types of glaucoma because of added risk (like the aforementioned pressure spikes)
  • May scare patients away (laser beams doing things to your eye can be a freaky proposition)
  • May lead to patients not coming in for checkups and monitoring, believing that they are “cured”
  • Doesn’t work 100% of the time

For Angle-Closure Glaucoma: Iridotomy

For angle-closure glaucoma, SLT by itself just doesn’t cut the mustard — enter iridotomy, also known as laser peripheral iridotomy (LPI). The no-nonsense explanation here is that a laser is used to open up the angle that is closed (you know, from ANGLE-CLOSURE glaucoma, right?). A small hole is made in the iris and voilà — you’ve got improved outflow of aqueous humor and less IOP. Sounds perfect right?

Well of course nothing in life is perfect, and LPI has its limits. The other surgical option for angle-closure glaucoma is cataract surgery as mentioned above, and like SLT, LPI comes with its own sets of pros and cons.

Pros of LPI (iridotomy)

  • Minimally invasive with none of the nasty side effects of more invasive cataract surgery, like infection and scarring, or risks like retinal detachment
  • Much safer in general than anything other than conservative options
  • Can be used for both acute angle-closure glaucoma emergencies and for chronic cases
  • Can be used in conjunction with other more conservative measures for great patient outcomes
  • Is a relatively inexpensive and short outpatient procedure
  • Insurance is more likely to cover LPI than cataract surgery if you don’t show signs of cataracts

Cons of LPI (iridotomy)

  • Not really a cure of the actual angle closure, the underlying problem. Unlike cataract surgery, the angle is not opened in LPI so this makes this more of a temporary band-aid solution and leaves the door open for future problems
  • Data points to cataract surgery being more effective
  • There are other options that are more cost-effective (in some cases)

For more on treatment options, visit this website or our writeup from CAKE online.

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