Numerous issues underlie unexplainable glaucoma progression

When glaucoma is progressing despite good intraocular pressure (IOP) control, clinicians should consider a variety of issues before advancing patients along the therapeutic ladder, said Robert Stamper, MD.

“We know from population studies that the incidence, severity, and progression of glaucoma consistently correlate with elevated IOP,” said Dr. Stamper, professor of clinical ophthalmology and director emeritus of the Glaucoma Service, University of California-San Francisco. “IOP reduction is currently the only treatment we can provide to patients with glaucoma. Therefore, it is important to explore situations associated with undetected IOP elevation.

“However, recognizing that glaucoma progresses over a decade in about 20% of patients despite good in-office, IOP control and that somewhere between 5% and 11% of patients with glaucoma become blind even with the best of care,” he added. “it is also worthwhile to consider other potentially modifiable factors that can explain the progression and address those problems before escalating into more aggressive therapeutic territory.”

Providing a checklist for patient evaluation, Dr. Stamper reminded colleagues–during the Glaucoma Symposium CME at the 2016 Glaucoma 360 meeting–to examine the eyes for exfoliative disease, which has been found to be a risk factor for glaucoma progression.

“If there is exfoliative disease, you may need to be more aggressive in your treatment,” Dr. Stamper said.

Gonioscopy and pachymetry

Gonioscopy and pachymetry

In addition, Dr. Stamper recommended performing bi-annual gonioscopy to detect angle closure, which can occur over time with cataract development and progression, and to check pachymetry, recognizing that IOP-measurement accuracy is affected by cornea thickness.

“In eyes where the cornea is naturally thin or thinned iatrogenically, IOP may be underestimated, and it may be necessary to set a lower IOP target than you would when treating an eye with average corneal thickness,” he said.

Elevated IOP outside of the in-office measurement is another issue to consider and can occur for a variety of reasons. Diurnal fluctuation can be checked by doing a “poor man’s” assessment, measuring IOP three times during office hours-first thing in the morning, mid-day, and in the late afternoon.

Significant IOP elevation may also occur in some patients in response to postural changes, and this situation may be evaluated by measuring IOP when the patient is upright and then in a supine position. In addition, patients should be asked whether they engage in activities where the head is below the heart, such as occurs with certain yoga poses or inversion therapy.

Patients who play brass or wind musical instruments may also be experiencing IOP elevations associated with those activities, and should be counseled about the effect, Dr. Stamper said.

Intake of a large fluid volume in a short period of time can also cause significant IOP elevation, and is something worth investigating.

“I don’t ask patients to modify their total daily fluid intake, but recommend they spread it out over the course of the day in order to prevent IOP spikes,” Dr. Stamper said.

Poor medication adherence, either because patients forget to use their medications or have difficulty with administration, should also be considered. All patients should be reminded about the importance of using their medications because glaucoma is a potentially blinding disease.

Optic nerve compromise

Optic nerve compromise

Risk factors for progression that are not related to IOP relate to situations affecting optic nerve perfusion or oxygenation and include arterial hypotension due to intensive treatment of systemic hypertension. Dr. Stamper noted that internists have been targeting lower systolic blood pressures for patients with hypertension, and while a patient’s systolic blood pressure may measure 120 mm Hg during a daytime office visit, it may fall to 90 mm Hg or lower at night.

“Watch out for orthostatic and nocturnal hypotension by asking patients if they get dizzy when they stand up after sitting or when getting out of bed, Dr. Stamper said. “If the answer is ‘yes,’ it may be an indication that they are being treated too aggressively with antihypertensive medications and a reason to contact the internist.”

Studies investigating an association between sleep apnea and glaucoma progression have not generated consistent results. However, it is reasonable to expect that sleep apnea can lead to glaucoma progression, considering it causes hypoxia. Dr. Stamper observed that he has had a few patients whose glaucoma progressed after they stopped using their CPAP machine for sleep apnea.

Other medical issues to consider because they may be affecting optic nerve health include the presence of anemia and conditions associated with poor peripheral circulation.

“Ask patients if they get migraines or get cold hands, feet, or fingers,” Dr. Stamper said. “These patients may benefit from adjunctive treatment with calcium channel blockers.”

Robert Stamper, MD

e. stamperr@vision.ucsf.edu

Dr. Stamper has no financial interests to disclose that are relevant to his presentation.