Hello lovely internet world and happy Monday!
It’s been another month, so I guess it’s time for another eye post from yours truly. Today’s topic? Glaucoma!
What is Glaucoma?
Okay, let’s start out with the basics. Glaucoma is an ocular disease in which the intraocular pressure of the eye (IOP) is too great for the eye itself. This causes progressive damage to the optic nerve, which, if left untreated, may cause blindness.
What causes increased pressure in the eye?
Believe it or not, the cause of increased IOP cannot always be determined. This is most commonly the case in Primary Open Angle Glaucoma (POAG). However, in many other types of glaucoma, the reason for increased pressure is more obvious, and may be the result of trauma, inflammation, damage to the structures that allow aqueous/aqueous humor (fluid in the front portion of the eye) outflow.
Types of Glaucoma
Because there are various different reasons for increased IOP, there are also many different types of glaucoma itself. I won’t go into details on all of them today, as that’d take forever, but here’s a brief overview.
- Open Angle Glaucoma
- This is the most common type of glaucoma. As mentioned in the previous paragraph, the cause of the increased pressure in POAG isn’t fully determined.
- Angle Closure Glaucoma
- This is, essentially, the polar opposite of POAG. Rather than having an open angle (aqueous outflow system), the angle is closed, preventing fluid from moving between the anterior chamber (area in front of the iris) and the posterior chamber (area between the iris and the lens. If this is confusing, you can read more on it in Why Does My Eye Doctor… Part 3.) Closure typically results from apposition of the iris to the edge of the cornea.
- Pigmentary Glaucoma
- Pigmentary glaucoma is a condition in which the angle is physically blocked by pigment, which has, over time, rubbed off of the posterior (back) portion of the iris (colored part of the eye).
- Pseudoexfoliation Glaucoma
- Pseudoexfoliation glaucoma, in many ways, is similar to pigmentary glaucoma, as they both arise from physical blockage of the drainage network. However, in the case of pseudoexfoliation glaucoma, the blocking substance is a whitish-grey protein-like material, as opposed to pigment.
- Neovascular Glaucoma
- As with the previous two types of glaucoma, the pressure elevation in neovascular glaucoma results from a physical blockage of the angle. In this condition, however, the angle is blocked by new blood vessels (neovascularization), which grow in the angle itself, as a result of improper blood flow (ischemia) in the retina.
And I could probably keep going on more obscure forms of glaucoma. But for today, I’ll call it good there.
Naturally, with so many different types of glaucoma, the method of treatment is also variable. However, most glaucoma treatment options fall under two categories – medical therapy or surgical intervention – both with the end goal of decreased intraocular pressure.
1) Medical therapy: Most commonly, this takes the form of eye drops, with some drops actively working to decrease aqueous output (ie beta blockers like Timolol), others working to open the drainage system (ie prostaglandins such as Travatan), and others doing a combination of both (ie ROCK inhibitors like Rhopressa).
2) Surgical intervention: This is admittedly a bit of a can of worms. Surgical treatments for glaucoma can be as simple as a laser procedure (SLT/ALT) that helps to open up the angle for better outflow, to as extreme as a trabeculectomy (which literally removes part of the angle to allow for direct communication with the end outflow vessels), and anything and everything in between.
For better or worse, glaucoma is a pretty insidious disease. Just as arterial hypertension has been referred to as the silent killer, glaucoma has been dubbed the silent blinder, simply because, as a rule, there aren’t many symptoms.
The blindness of glaucoma stands in stark contrast to the vision loss in conditions like macular degeneration. In macular degeneration (which affects the most central, most defined part of your vision) the vision loss is pretty much impossible to ignore – it’s literally right in front of you at all times. With glaucoma, however, the vision loss creeps in slowly from the sides.
Additionally, in most cases, there is no pain with glaucoma. Yes, the pressures may be too high for the eye, but they’re not high enough to cause physical discomfort.
And so, without consistent testing, glaucoma may go undiagnosed for years.
Admittedly, glaucoma prognosis is a hard one for me, because there’s no guarantee.
In school, we are generally taught that glaucoma is a slow moving disease – there’s no need to rush treatments. And, especially in POAG, that’s true.
However, not all glaucoma is primary open angle glaucoma.
And not all POAG progresses the same.
I’ve seen patients who have been on single drop therapy for years with virtually no change to their optic nerve and visual field.
I’ve worked with patients who are on maximum medical therapy (three different eye drops with different mechanisms of action) and are still progressing.
I’ve had patients who have mild visual field loss that barely impacts their daily functioning.
And I’ve had patients who are literally blind, with no perception of light in either eye, from aggressive glaucoma and improper treatment.
It just… depends.
Glaucoma Risk Factors
What does glaucoma depend on? Well, that’s where some risk factors come into play.
- Age – generally, a younger diagnosis is a worse prognostic factor
- IOP – often (but not always), the higher the IOP, the greater risk of damage
- Being black, Asian or Hispanic
- Family history – glaucoma is definitely hereditary. If a close family member has glaucoma, and especially if they went blind from glaucoma, tell your eye doctor!
- Medical conditions: Other medical conditions, like diabetes, heart disease, and high blood pressure, put stress on ocular tissues and can increase the risk of glaucoma.
- Thin corneas – odd, but true
- Being extremely nearsighted or farsighted
- Eye trauma
Since glaucoma is a (generally) asymptomatic, potentially blinding disease, please go to the eye doctor regularly – especially if you have any of the above risk factors. The sooner glaucoma is found and treated, the better the long-term prognosis.
Glaucoma is not a curable disease, but it is a treatable disease. If you are diagnosed with glaucoma, follow your doctor’s advice. If they say you need drops, you probably do. If they say you need surgery, you probably do…even if you don’t notice any significant changes to your vision.