"The current definition is a progressive optic neuropathy in which intraocular pressure may be an important factor. Pressure is a factor, but high pressure is not necessarily required for a diagnosis of glaucoma," said Michael Stewart, MD, assistant professor, ophthalmology department, Mayo Clinic, Jacksonville, FL.
Dr. Stewart wants optometric technicians to have a good understanding of not just the clinical definition of glaucoma but the most common medical and surgical treatments and the tests and instruments used to monitor glaucoma patients and suspects.
"Glaucoma is often referred to as the sneak thief of sight," he said, explaining that except in advanced cases, primary open-angle glaucoma (POAG) is largely asymptomatic, and patients may not be aware of it until they experience irreversible vision loss.
"Glaucoma is one of those things that needs to be looked for fairly carefully at every visit. Especially with patients in their 40s and 50s, if they've got risk factors, we need to address those," Dr. Stewart said.
The knowledge base for a well-informed optometric technician includes understanding the types of glaucoma. While 90% of cases are POAG, which is largely asymptomatic and requires long-term therapy, some patients will present with less common types such as acute angle-closure glaucoma. In normal-tension glaucoma, a subgroup of POAG, IOP is normally not elevated, yet the eye will show signs of optic nerve damage.
Complaints of headaches, nausea, vomiting, pain behind the eyes, extremely blurred vision, and halos around lights may indicate angle-closure glaucoma. This form of glaucoma typically develops very quickly and demands immediate medical attention.
Dr. Stewart explained that glaucoma is classified as primary or secondary. Primary glaucoma is a specific problem of outflow and improper drainage, while secondary glaucoma refers to glaucoma that caused by another ophthalmic process.
Technicians play a key role in screening patients, gathering important information such as a family history, and identifying risk factors such as age, gender, and race, as well as signs such as IOP, optic nerve status, and systemic hypertension, he said.
Skill at conducting various assessments is valuable. For instance, technicians need to be able to reproduce visual fields effectively and efficiently and tell the difference between normal and abnormal results. Their expertise can help determine when a deviation is the result of patient fatigue and when is it a true glaucomatous defect.
Within the ophthalmology clinic in which Dr. Stewart practices, knowledgeable technicians have a green light to conduct testing such as visual fields and optical coherence tomography so that all information is ready when he sees the patient.
"This streamlines things and makes for better patient care," he said.
Technicians also should be trained to perform pachymetry, which measures corneal thickness, as part of their assessment of patient risk factors. This measurement correlates fairly closely with the risk of glaucoma and subsequent vision loss.