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Can glaucoma develop when eye pressure is within the usual range?

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eye disease An ophthalmologist performing LASIK eye surgery.

Yes, it is possible for glaucoma to develop even when eye pressure is within the typical range. While increased intraocular pressure is a significant risk factor for the disease, there is no single pressure level that is universally indicative of glaucoma.1

The susceptibility of an individual's optic nerve and retinal ganglion cells to damage varies widely. Consequently, a condition known as normal-tension glaucoma (or low-tension glaucoma) can occur in individuals whose eye pressure remains within the standard range of 10 to 21 mm of mercury. Conversely, some individuals with pressures exceeding 21 mm—a condition called ocular hypertension—may never exhibit signs or symptoms of the disease.1

Because glaucoma can lead to permanent vision loss, early diagnosis is essential, and relying solely on pressure measurements may not always be sufficient to identify the condition in all patients.1