Take a moment and think of the last patient you saw who had advanced glaucoma. You may be thinking of a patient with reduced visual acuity, or even someone who met the criteria for legal blindness. But according to ICD-10, advanced glaucoma is defined as a glaucomatous optic nerve appearance with either a visual field defect within the central 5° of fixation, or visual field defects on both the superior and inferior hemifields. In mild glaucoma, the visual field is completely full, and moderate glaucoma would be anything between the two. In other words, severe glaucoma is defined by the location of the defects, not by the total magnitude of damaged nerve fibers. This likely means that we have many patients in our practice with advanced glaucoma who have visual field defects that are threatening central visual function.
What are we to do in such cases? I would argue that we do well to be aggressive with intraocular pressure (IOP) lowering. Therapy for each individual patient must be tailored; in advanced glaucoma, more often than not, we want to seek IOP in the low teens or occasionally lower. In the Advanced Glaucoma Intervention Trial, patients who were lucky enough to achieve such low pressures did not, on average, demonstrate visual field progression.1
Surprisingly, patients with advanced glaucoma may not seem advanced at first glance. Optical coherence tomography average retinal nerve fiber layer values can be borderline or even still in the normal zone, as deep, focal defects may be present. We must pay attention to the location of the defects and classify appropriately in order to recognize that we are dealing with advanced disease that threatens central visual function.
In summary, ICD-10 brought a host of new diagnoses. And while W56.22, “struck by orca, initial encounter” and other random codes may not be so common, advanced glaucoma is more prevalent than we might imagine. We should be aggressive and take advantage of our efficacious modern therapies in delivering low IOP to this group of patients with threatened central vision.
1. 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 Oct;130(4):429-440.
Dr. Nathan M. Radcliffe is the director of the glaucoma service and a clinical assistant professor at New York Univeristy Langone Ophthalmology Associates and is a cataract and glaucoma surgeon at the New York Eye Surgery Center.