Pointwise approach helps identify visual field damage progression

MIAMI — Evaluation of repeated visual field tests using a pointwise approach can provide the most sensitive and specific indication of glaucomatous progression, according to a surgeon speaking here.

Donald L. Budenz, MD, said when using visual field tests to detect glaucomatous progression the surgeon should look for three things: new abnormalities, whether an existing abnormality has enlarged and whether an existing abnormality has deepened.

“If you look for all three in your visual field tests, and you don’t find them, then you can tell the visual field is stable,” said Dr. Budenz, here at Bascom Palmer Eye Institute’s Controversies in Glaucoma Management Battle on the Beach.

According to Dr. Budenz, the glaucoma hemifield test protocol is not reliable for detecting progression because the visual field is already presumably abnormal, making the pattern deviation unreliable.

He recommended following pointwise criteria when looking for progression of visual field abnormalities. This involves looking for a cluster of three points in an constricted area of the visual field that are depressed at the P < .05 level and one point at the P < .01 level.

As physician use of these tests increases, they will need to be more vigilant about false positives as well, Dr. Budenz noted. He said this involves repeating the visual field test at least once to confirm a suspected progression, although he noted the Normal Tension Glaucoma Study suggested that a minimum of two repeated tests may be necessary.

By Dr. Budenz’s definition, an abnormality should be considered to have worsened (deepened or enlarged) if two or more points within or adjacent to an existing scotoma have worsened by at least 10 dB or three times the average of the short-term fluctuation, “whichever is larger.” He noted this is most sensitive when the test is confirmed on two subsequent tests.

“Secondly, look at the patient not as a glaucoma case, but as a whole patient who may also develop cataract or may have a completely new diagnosis, such as a vein occlusion. You want a good clinical correlation to go with that visual field change,” he said.