Central visual field changes associated with acquired pits of the optic nerve

With the increased use of a hand-held indirect lens and slit-lamp biomicroscopy for stereoscopic viewing of the optic nerve, the authors believe that an acquired pit of the optic nerve is more common than was recognized previously. This increased recognition has led to the awareness that the central visual field was affected frequently in the presence of such an acquired pit.

The authors retrieved the charts of a series of 97 patients who had an acquired pit of the optic nerve during an 18-month period and retrospectively reviewed the automated visual fields associated with these pits using the Humphrey Visual Field Analyzer Programs 30-2 and 10-2 and looked for involvement of the central visual field.

In 81.7% of the acquired pits of the optic nerves, one of the central-most test points (3 degrees from fixation) in the appropriate hemifield on the 30-2 format was depressed severely by Statpac II (P < 0.5). The authors therefore restudied as many patients as possible using the 10-2 format to determine the extent of central visual field involvement in the presence of an acquired optic nerve pit. Among these patients, the 10-2 format demonstrated that the approach of the defect to fixation varied, but was frequently inside 3 degrees, reaching between 1 degrees and 3 degrees from fixation in 96.7% of the eyes with depression of at least one central point on the 30-2 format. It was more likely that an acquired pit located at the inferior pole of the optic nerve would produce a visual field defect within 3 degrees of fixation than such a pit at the superior pole (P = 0.03).

The authors showed that the presence of an acquired pit in an optic nerve damaged by glaucoma frequently is associated with a threat to fixation.