Diagnosis: chronic primary open angle glaucoma
This patient has chronic primary open angle glaucoma (POAG) or of both eyes which has likely progressed in the setting of poorly controlled intraocular pressures and glaucoma drop discontinuation over the past few months.
Glaucoma is an optic neuropathy typically caused by intraocular pressures (IOP) that are too high in the eyes. The optic neuropathy first causes peripheral vision peripheral vision loss before affecting central vision. For this reason, it is often asymptomatic in the early phase, as patients don’t sense peripheral vision loss and typically can’t feel when the intraocular pressure is elevated. Normal intraocular pressures range from 10-21 mmHg. However, the target pressure for patients with glaucoma depends on their level of glaucoma, with more advanced cases requiring very low pressures. On examination the optic nerves exhibit cupping and in advanced cases even pallor. This patient’s optic nerves had significant cupping with a cup-to-disc (C/D) ratio of 0.9-9.5 and pale appearance.
Treatment
First line treatment is medical management with topical eye drops to lower intraocular pressure. The patient brought in 5 drops all of which are commonly used for glaucoma. A brief description of the drops is provided below:
Pilocarpine (miotic agent) – causes miosis and increased outflow of aqueous fluid through the trabecular meshwork
Timolol (B-blocker) – decreases intraocular pressure by suppressing aqueous fluid production. Even the eye drop form can be associated with common systemic side effects of B-blockers including bradycardia, brochospasm, decreased libido, and depression.
Dorzolamide (carbonic anhydrase inhibitor) – decreases intraocular pressure by suppressing aqueous fluid production
Brimonidine (selective adrenergic agonist) – decreases intraocular pressure by suppressing aqueous fluid production
Travoprost (prostagladin agonist) – decreases intraocular pressures by increasing aqueous outflow through the uveoscleral pathway. Latanoprost is another commonly used topical prostaglandin analogue.
There are 2 additional glaucoma drops which were recently FDA:
Netarsudil (Rho kinase inhibitor) – decreases intraocular pressure by increasing trabecular outflow, decreasing episcleral venous pressure, and decreasing aqueous production
Latanoprostene bunod (prostaglandin analogue with nitrous oxide moiety) – the addition of the nitrous oxide enhances trabecular outflow to decrease intraocular pressure
Testing
Below are images of a normal visual field to contrast the significant peripheral vision loss sustained by the patient in this case.
Here is an example of a normal optical coherence tomography (OCT) of the optic nerve, which measures the thickness of the optic nerve. Healthy nerves have thicker tissue (indicated by green on the scan), while nerve that have sustained neuropathy and apoptosis have thinner measurements (indicated by red on the scan).
Counseling
While patients with glaucoma can unfortunately experience significant vision loss, low vision resources are available to assist with maximizing the use of their available vision. Resources include low vision magnifiers, mobility training, and brail education. It is important to share these available resources with patients.
Additionally, while state requirements may vary, patients with significant peripheral vision restriction should be counseled against driving.
Finally, it is important to educate patients on the genetic inheritance of glaucoma and importance of screening eye exams for relatives.
There are not contraindications to flying for glaucoma patients. Patients who have had eye surgery involving injection of a gas bubble in the eye (typically retina surgery) are advised not to fly until the gas bubble has dissipated.
References and Additional Resources:
- “Eyewiki: Primary Open Angle Glaucoma.” Available at: https://eyewiki.aao.org/Primary_Open-Angle_Glaucoma.
- “Eyewiki: Medical Management for Primary Open Angle Glaucoma.” Available at: https://eyewiki.aao.org/Medical_Management_for_Primary_Open_Angle_Glaucoma.
- Gupta D & Chen PP. Glaucoma. Am Fam Physician. 2015;93(8):668-674.
- Rosenberg EA & Sperazza LC. The Visually Impaired Patient. Am Fam Physician. 2008;77(10):1431-1436.
Case 5 Index
Case 5 Introduction
Case 5 Physical Exam
Case 5 Ophtho visit