Picturing the Future of Glaucoma
By: Paul M. Karpecki, OD, FAAO
Clinical Director – PECAA
I’ve received numerous requests to discuss future technologies that PECAA Members need to be aware of. This seems like a good time to focus on glaucoma and each month we’ll try to cover a disease focus.
There is no question that optometry has to take a lead role in the management of patients with glaucoma simply because the profession sees 85% of all exams and is most likely to make the original diagnosis, manage treatment including laser procedures, referral for surgery and patient compliance. I think there are five things that will assist and/or help sort out the future of glaucoma:
1. Better diagnostics. There is no question that OCT has changed our ability to manage glaucoma. It allowed us to treat proper patients meaning a better diagnosis of glaucoma, it allowed us to begin treatment earlier to prevent blindness and it allowed the profession to manage these patients at an equal level to other eye care practitioners. However diagnostics must advance given the fact that we are all getting busier. In this fast-paced future of eye care, doctors need to understand what they are looking at, but also need to know when green means go, yellow for caution or red for stop. In other words, as companies bring in more complex diagnostic technology they also have to make it simpler to use. Corneal hysteresis has been shown to be the most predictive measurement of visual field loss progression and plays a key role in deciding to treat and even what we might expect a glaucoma therapy to do. Finally we have 24 hour home monitoring of IOP with technologies like iCare HOME. And even a hand help ERG that can measure for decreased conductivity.
2. MIGS and other non-invasive procedures. The introduction of the iStent in June 2012 has forever changed glaucoma treatment. Today and in the near future we have multiple MIGS technologies including Cypass, Xen, ABiC, KDB, ECP, iDose and iStent Supra. Just looking at the sheer number of options almost ensures growth in these procedures, but the primary reasons we as optometry need to know these is to help manage patient compliance, have options for those on maximum therapy, have glaucoma and cataracts and to replace invasive surgeries like a trabeculectomy. I believe the future will be a greater combination of laser procedures like SLT and especially MIGS, in addition to therapeutic treatment.
3. Better understanding of the disease. The fact is we don’t fully understand what causes glaucoma. We know that IOP is a risk factor and we know of other risk factors like corneal thickness, hysteresis, family history, age, race, high myopia, systemic conditions like diabetes, previous trauma, chronic inflammation etc., but we don’t truly know the cause. Is it blood flow or is there some other cause for neurodegeneration, metallic changes or neuropathy? Knowing the cause will allow us to treat the disease more effectively. The theory proposed by John Berdahl, MD suggests that it may be caused by an imbalance between IOP inside the eye and cerebral spinal fluid pressure (or Intracranial pressure—ICP) around the optic nerve affecting the metabolic needs. This can be supported by the fact that patients with idiopathic intracranial hypertension get a bowing of their optic nerve and 50% of astronauts develop vision loss because their CSF increases disproportionately higher than the IOP resulting in a hyperopic shift and optic nerve edema. So the key ratio may be IOP minus ICP as opposed to simply an elevated IOP. They have developed a set of nighttime goggles and a pump that in early clinical trials has been shown to decrease IOP substantially and prevent glaucoma progression. This could be an ideal treatment for Normal Tension Glaucoma if testing pans out.
4. New therapeutics and drug delivery devices. It’s been 2 decades since we’ve had a new glaucoma drug but that could change in the next 3-6 months. B+L’s Vyzulta (latanoprostene bunod ophthalmic solution) 0.024% is a nitric oxide-donating prostaglandin F2-alpha analog that in a recent study was shown to lower IOP by 9mmHg compared to timolol at 7mmHg.(1) Keep in mind that few if any previous glaucoma medications showed superiority to timolol in FDA trials. Perhaps it is the dual mechanism of action affecting both uveoscleral outflow and trabecular outflow of this drug that make the difference.(2) Nitric oxide (NO) is an important mediator with important effects on the vascular system and as a mediator of smooth muscle relaxation (and vasodilatation) including in the trabecular meshwork and in regulation of Schlemm’s canal. Studies show that glaucomatous eyes have lower levels of NO activity in the trabecular meshwork. A new drug class, RhoKinase inhibitors, may also change the landscape of glaucoma management because of their efficacy in IOP lowering but also, in the case of Rhopressa (netrarsudil), as a different mechanism of action. The second drug from Aerie pharmaceuticals with significant IOP lowering is Roclatan (netarsudil + latanoprost). Very recently the phase III data for Roclatan was released and IOP-lowering effect was 1-3 mmHg greater than monotherapy with either of its two components throughout the duration of the study. Knowing that adherence to medications is a major issue with non-symptomatic conditions like glaucoma, it is inevitable that new drug delivery systems will need to be utilized. Exciting developments in phase III clinical trials include Ocular Therapeutix travoprost eluding punctal plug technology that may last 3 months with each plug.
5. Treating the ocular surface. Another way to enhance adherence is to remember to manage the ocular surface. Patients with staining, blurred vision and irritation/dryness from drops like prosta-glandin antagonists or preservatives in glaucoma medications can cause patients to decrease or even discontinue use. Something as simple as managing the ocular surface may increase compliance and overall patient comfort.
Glaucoma is a key disease for optometry and these five elements may well dictate the future of disease management, our understanding and innovations in patient care.
Summary:
Special recognition to Review of Optometry, Author Paul M. Karpecki, OD, FAAO
1. Weinreb RN, Scassellati Sforzolini B et al. Latanoprostene Bunod 0.024% versus Timolol Male-ate 0.5% in Subjects with Open-Angle Glaucoma or Ocular Hypertension: The APOLLO Study. Ophthalmology. 2016 May;123(5):965-73.
2. Hedman K, Alm A. A pooled-data analysis of three randomized, double-masked, six-month clini-cal studies comparing the intraocular pressure reducing effect of latanoprost and timolol. Eur J Ophthalmol. 2000;10(2):95-104.
