A 58-year-old man with POAG has progressive visual field loss despite IOP of 14 mmHg on maximum tolerated medical therapy including a prostaglandin analogue, beta-blocker, and topical carbonic anhydrase inhibitor. Central corneal thickness is 540 microns. According to current evidence, what is the next appropriate target IOP to slow progression?

• A Maintain at 14 mmHg as it is already below 21 mmHg
• B Reduce by a further 30 percent from baseline per CNTGS principles ✓
• C Reduce to 10 mmHg or below
• D Add oral acetazolamide to achieve IOP below 8 mmHg

Explanation

The Collaborative Normal Tension Glaucoma Study (CNTGS) demonstrated that reducing IOP by 30 percent from baseline significantly slows visual field progression in normal-tension glaucoma. Since this patient has progressive field loss at 14 mmHg, his baseline IOP was likely higher, and a 30 percent reduction from that baseline is the evidence-based target. Simply staying below 21 mmHg or aiming for arbitrary low values without evidence is inappropriate.

Reference: Collaborative Normal Tension Glaucoma Study (CNTGS), American Journal of Ophthalmology, 1998 ed.

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Written and medically reviewed by the StethoPrep medical team.