Page 50 - 21st Century Perspective - Glaucoma Supplement

Micromanaging the Various Diagnostic Tests In Glaucoma

There are two notable aspects of glaucoma patient care: First, many factors must be considered in
the glaucomatous evaluation, and therefore optometrists are not required to micromanage every

minor nuance of these various tests. Second, with rare exception, glaucomatous optic neuropathy is
a slowly progressive disorder, which gives ample time to methodologically ponder the course of
patient management.

Intraocular pressure is a dynamic measurement that varies throughout the day. A patient whose IOP
was 18 mm Hg at the previous office visit but now measures 20 mm Hg at the current office would
not necessarily require initiation of therapy or addition to current therapy. Depending on the stage of
glaucoma, one would always recheck the IOP in 2 to 4 more months. Again, there is no rush.

Visual fields are notoriously variable. Altering patient management based on the results of a single
visual field test is only valid in exceedingly rare circumstances. Numerous studies have confirmed
that, at the very least, two (and preferably three) corroborating fields are required to determine true
change.

Corneal pachymetry is, for most all, a stable parameter. There is no precise, valid nomogram to help
us determine if we must alter IOP by a certain amount based on corneal pachymetry results.

However, we know that a patient who has a cornea that is considerably thicker than normal may
have a slightly artificially inflated IOP measurement. And, we know that patients with corneas that
are physiologically thinner than normal have — to some imprecise degree — an increased risk for
developing glaucoma (or sustaining progression). If the cornea is thin secondary to refractive
surgery, then one can generally estimate that the IOP measurement may read a bit lower than if the
cornea were of normal thickness.

Even “objective” tests are only relatively objective, as seen in ​Figure 27​, which shows apparent loss
in high-quality nerve fiber layer measurements. The nerve fiber layer does indeed appear to be
steadily thinning, until the fourth annual measurement shows it has normalized. This shows how
important it is to not focus on one diagnostic parameter, but rather to be attentive to the
comprehensive diagnostic assessment.

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