Comparison of 24-2 and 30-2 perimetry in glaucomatous and nonglaucomatous optic neuropathies

To determine whether the 24-2 Humphrey visual field (HVF) (Humphrey, San Leandro, CA) strategy provides information comparable to that provided by the 30-2 strategy in patients with optic nerve disease.

In part A of the study, an occluder device was designed to cover the additional outer 22 points tested in the 30-2 strategy of 187 HVFs from neuro-ophthalmology patients with nonglaucomatous optic neuropathy and 206 HVFs from patients with glaucoma. This device converted the gray scale and probability plots of the 30-2 HVF to a 24-2 field. Fields were initially read using the occluder and then were read in a masked manner without the occluder and compared. In part B, 15 healthy volunteers performed both 30-2 and 24-2 HVFs. Testing time and global indices were compared. Ninety-five percent of the fields in the neuro-ophthalmology patients, 96% of the fields in patients under observation for suspected glaucoma, 98% of the fields in patients with ocular hypertension, and 100% of the fields in patients with glaucoma were read similarly with the 24-2 and 30-2 strategies. In the few cases in which a discrepancy was noted between the 24-2 and the 30-2 fields, appropriate clinical management would not have been compromised by using the 24-2 strategy. Most of these cases were in patients with idiopathic intracranial hypertension and very subtle nerve fiber bundle defects. The 24-2 strategy had a significantly lower pattern standard deviation (P < 0.01) and corrected pattern standard deviation (P = 0.05) than did the 30-2 strategy. In addition, the 24-2 strategy shortened the standard threshold testing time by 28% in normal volunteers (P < 0.0001 ).

In most cases, the 24-2 testing strategy provides information comparable to that provided by the 30-2 strategy in a shorter time and with less variability. A 30-2 HVF may be warranted in patients under observation for evolving idiopathic intracranial hypertension.