The 24-2 Visual Field Test Misses Central Macular Damage Confirmed by the 10-2 Visual Field Test and Optical Coherence Tomography.

The macular region (i.e., ±8° from fixation) covers less than 2% of the retinal area, but contains over 30% of the retinal ganglion cells (RGCs).1 Glaucomatous damage to the macula (central ±8°) is relatively common, involves defects that are deep and local as well as those that are shallow and widespread, and can occur early in the disease process.2–11 Because central vision is necessary for tasks such as reading, recognizing faces, and driving,12 early detection of macular damage is vital to clinical practice. The visual field (VF) pattern most widely used to detect glaucomatous damage, the 24-2 test pattern, does not adequately test the macular region, as the 6° grid of the 24-2 pattern has only four points within ± 8°. When these four 24-2 central points are displaced to take into account the anatomical position of the RGCs, they fall outside of the region of the macula most affected by glaucoma.7,8 It is therefore not surprising that the 24-2 VF misses glaucomatous damage of the macula that a test pattern with a 2° grid (i.e., the 10-2 pattern) detects.5–10,13,14 For example, Langerhorst et al.5 found that the 10° (2° grid) VF showed a greater number, and more severe, glaucomatous macular defects than a 30° (6° grid). Similarly, Traynis et al.9 found that 22.7% of the eyes classified as normal on the 24-2 VF were abnormal on the 10-2 (2° grid) VF. Further, in analyzing progression of macular defects, Park et al.13 found that 70.8% of the eyes with progression detected by the 10-2 VF were missed by the 24-2 VF. These studies used various methods of interpreting the 24-2 VF. However, they did not address the ability of the 24-2 to detect macular damage with the typical metrics used by the clinician. Here we ask: Can the clinician detect eyes with macular damage using the standard metrics of the 24-2 VF, such as mean deviation (MD), pattern standard deviation (PSD), and glaucoma hemifield test (GHT)? In addition, unlike previous work that implicitly assumed the 10-2 VF is the gold standard for defining macular damage, we defined an abnormal macular region based upon both 10-2 VF and optical coherence tomography (OCT) macular RGC and/or RNFL damage.8 In particular, an eye was classified as having macular damage only if the 10-2 VF and OCT RGC and/or probability plots showed abnormalities in the same region of the macula. Thus, we tested the hypothesis that clinicians using standard 24-2 metrics may miss eyes with confirmed macular damage. In addition, we evaluated the patterns of macular damage that were missed.