Article

CLINICAL: GLAUCOMA

PRESSURED TO CHOOSE

WHEN SHOULD YOU TREAT AN OCULAR HYPERTENSION PATIENT?

OCULAR HYPERTENSION is an IOP greater than 21mmHg. Though the optic nerve head and retinal nerve fiber layers are normal, the VF shows no glaucomatous defects, gonioscopy is normal, and there are no other signs of ocular conditions contributing to the IOP elevation.

Yet, because ocular hypertension can transition to glaucoma, we must be aware of the risks for this transition and how to best manage these patients.

THE RISKS

The Ocular Hypertension Treatment Study (OHTS) provides us with a template for the risk of patients who may transition to primary open angle glaucoma (POAG):

  1. Age. The older a patient (by decade), the greater the risk to converting to POAG.
  2. IOP. The higher the IOP, the greater the risk of converting to POAG.
  3. Central corneal thickness (CCT). If it’s less than 555μm, there is a 3.4% annual increased risk of converting to POAG.
  4. Vertical cup-to-disc ratio. If it’s greater than 0.50, there is a greater risk of developing POAG.
  5. Pattern standard deviation. The higher the pattern standard deviation value, the greater the risk of converting to POAG.
  6. Relationship of IOP and CCT. A total of 36% of patients with IOPs higher than 25.75mmHg and corneas 555μm or thinner developed glaucoma compared with 2% of patients with IOPs of 23.75mmHg or less and corneas thicker than 588μm.
  7. Intervention. Through a five-year-period, a patient with an IOP at 24mmHg or greater who did not receive treatment had a 9.5% overall risk of developing glaucoma compared with 4.4% of patients who did receive treatment.
  8. Race. Glaucoma is the No. 1 cause of blindness among African Americans. OHTS shows that medical treatment is as effective in African Americans as those classified as “others,” and that African Americans have similar reductions in IOP and decreases in the incidence of POAG.

You may find value in using a risk calculator (http://bit.ly/2nX9IbF ) to predict the chances of a patient transitioning to POAG through five to 10 years.

MANAGEMENT

When it comes to treatment, OHTS tells us to act on patients who are at high risk for developing glaucoma, for example: a patient with a long life expectancy, an IOP of 26mmHg or greater, a CCT of 555μm or thinner and a vertical cup-to-disc ratio greater than 0.50. This patient may develop a noticeable VF defect during his or her lifetime, based on findings in OHTS.

Treatment options are IOP-lowering drugs or a selective laser trabeculoplasty (SLT). The factors of both, such as efficacy and cost, should be discussed with patients. (See web version of this column for more specifics.) In terms of monitoring, if a patient had a shorter life expectancy, an IOP of 26mmHg or greater, a 555μm or thinner CCT and a cup-to-disc ratio of 0.5, the likelihood of a noticeable VF defect is low. Monitoring and then treating at the first signs of glaucomatous damage is reasonable. OM