How is the damage from primary open-angle glaucoma (POAG) prevented or delayed?

Updated: Mar 16, 2020
  • Author: Kristin Schmid Biggerstaff, MD; Chief Editor: Inci Irak Dersu, MD, MPH  more...
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Answer

Considering all of the above, no consensus exists on what is the appropriate medical treatment for preventing or delaying the damage due to POAG when a patient has only elevated IOP and no other signs of POAG. To date, no one has been able to define conclusively which subgroups will develop damage if left untreated, as opposed to those who will not sustain damage even if not treated.

The question of medical therapy versus observation in patients with solely elevated IOP is being addressed in the OHTS, an ongoing multicenter randomized clinical trial. The OHTS is a multicenter, prospective, randomized, controlled, clinical trial studying over 1600 subjects to evaluate the safety and efficacy of medical treatment in preventing or delaying onset of visual field loss and/or optic nerve damage in patients with OHT who are at moderate risk for developing POAG. Their medical therapy goal for the treated group is stepped therapy to reduce IOP by at least 20% from the average baseline IOP with its treated absolute value of 24 mm Hg or less. So far, their results show a 10% risk over 5 years of developing glaucoma in those patients with baseline IOP of 24-31 mm Hg. This risk was reduced to 5% with medical therapy. The OHTS has also revealed the importance of pachymetry as a diagnostic tool as well as in the workup.

Several sources agree on this initial goal of 20-25% reduction, while some specialists feel that more absolute numbers of less than 15 should be the goal of treatment. Keep in mind that the IOP goal must be set independently for each patient, depending on the risk factors, as an IOP level for one person with minimal risk factors may be far too high for a patient with multiple risk factors for sustaining glaucomatous damage.

Other regimens have been suggested, as follows: for minimal risk factors, consider lowering IOP by 20-30%; if moderate number of risk factors are present, lower by 30-40%; and in cases of numerous risk factors with markedly elevated pressures, reduction in the 40-60% range may need to be achieved to prevent neuronal loss.

If the patient is older than 65 years, consider treatment to keep IOP 25 mm Hg or less, secondary to 3% risk of vascular occlusion in OHT patients.

In any case, the target IOP should be reevaluated periodically, and regular review of IOP trends should be performed to determine whether the patient is consistently maintaining that goal.

According to Preferred Practice Patterns published by the American Academy of Ophthalmology, the interval between follow-up visits should be determined based on whether the target IOP has been achieved and whether glaucoma is progressing. If there is progression, treatment should be adjusted and the patient should be monitored every 1-2 months. If there is no progression but IOP is not at target, follow-up visits every 3-6 months are appropriate. If there is no progression and the IOP is at target, follow-up visit intervals can be extended to 6-12 months.


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