Patient compliance remains a challenge, but new agents on the horizon are offering hope in the field of glaucoma.
This article was reviewed by Joseph F. Panarelli, MD
Glaucoma, the leading cause of irreversible blindness in the United States, is caused by ocular hypertension, which damages the optic nerve and results in visual field loss.
There is no cure, but the disease can be managed with pharmacologic therapies, among other more invasive treatments, that lower and stabilize intraocular pressure (IOP).
Joseph F. Panarelli, MD, associate professor in the Department of Ophthalmology at NYU Langone Medical Center, New York, and Sahar Bedrood, MD, PhD, a glaucoma specialist at Acuity Eye Group, and assistant professor of clinical ophthalmology at the USC Roski Eye Institute, Los Angeles, recently spoke on the current state and future of glaucoma therapy and how compliance may not be an issue in the coming years.
IOP and glaucoma progression
IOP reduction is the only known modifiable risk factor for open-angle glaucoma. However, studies have shown that disease progression and blindness are still possible even in patients on maximum medical therapy.1-3
How IOP factors into visual field loss isn’t entirely clear. According to Dr. Bedrood, one theory—known as the stress/strain model—is that IOP strains the sclera and optic nerve, causing apoptosis and loss of retinal ganglion cells.
Another theory—the vascular theory—is when the blood vessels in the optic nerve don’t get enough oxygen, which leads to apoptosis, nerve fiber layer loss, and, eventually, visual field loss.
No two cases of glaucoma are alike, and progression rates vary from person to person.
“Some patients who have a very strong genetic component are going to progress very quickly, and some, not so much,” Dr. Bedrood said.
Co-morbidities such as sleep apnea and IOP fluctuations are other risk factors for visual field progression and greater visual field loss in certain patients.
The causes of IOP fluctuations are multifactorial and can be due to poor treatment compliance, genetics, and a decline in treatment effectiveness over time.4
“After 10-plus years of treatment, some of those treatments that initially worked may not work as well,” Dr. Bedrood said. “Sometimes, patients respond really well in the beginning and then over a couple of months or years they don’t, and then they fluctuate their IOP.”
Over a decade, selective laser trabeculoplasty (SLT) will wear off, requiring patients to have a touchup or a second round of treatment. Patients may develop an allergy or intolerance to glaucoma drops as well.
“Over a course of 10 years, a lot can change,” Dr. Bedrood said. “Their rate of progression can fluctuate. Their tolerance of drugs can fluctuate. Oftentimes after 10, 15, or 20 years, we’re looking at other modalities of treatment like surgery or something that can regulate their pressure a little bit better—other additional drugs, for instance.”
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2. Musch DC, Gillespie BW, Niziol LM, et al. Intraocular pressure control and long-term visual field loss in the Collaborative Initial Glaucoma Treatment Study. Ophthalmology 2011;118(9):1766-73.
3. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators. Am J Ophthalmol 2000;130(4):429-40.
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5. Tang W, Zhang F, Liu K, Duan X. Efficacy and safety of prostaglandin analogues in primary open-angle glaucoma or ocular hypertension patients: A meta-analysis. Medicine (Baltimore) 2019;98(30):e16597.
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9. Weinreb RN, Liebmann JM, Martin KR, et al. Latanoprostene Bunod 0.024% in Subjects With Open-angle Glaucoma or Ocular Hypertension: Pooled Phase 3 Study Findings. J Glaucoma 2018;27(1):7-15.
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12. Walters TR, Ahmed IIK, Lewis RA, et al. Once-Daily Netarsudil/Latanoprost Fixed-Dose Combination for Elevated Intraocular Pressure in the Randomized Phase 3 MERCURY-2 Study. Ophthalmology Glaucoma 2019;2(5):280-9.
13. Allergan. Allergan Announces Positive Topline Phase 3 Clinical Data for Bimatoprost SR (Sustained-Release) Implant for IOP Lowering in Patients with Open-Angle Glaucoma or Ocular Hypertension. 2018.
14. Nordstrom BL, Friedman DS, Mozaffari E, et al. Persistence and adherence with topical glaucoma therapy. Am J Ophthalmol 2005;140(4):598-606.