Detection of central visual field defects in early glaucomatous eyes: Comparison of Humphrey and Octopus perimetry

To compare the detection rate of central visual field defect (CVFD) between the 30-degree Octopus G1 program (Dynamic strategy) and the HFA 10-2 SITA-Standard test in early glaucoma eyes not showing any CVFD on the HFA 24-2 SITA-Standard test.

One eye of 41 early glaucoma patients without CVFD in the central 10° on HFA 24-2 test was tested with both the HFA 10-2 test and the Octopus G1 program 15 minutes apart, in random order. The primary outcome measure was the comparison of CVFD detection rates. Secondary outcome measures comprised the agreement in detecting CVFD, and the comparison of test durations and the numbers of depressed test points outside the central 10-degree area between the HFA 24-2 test and the Octopus G1 program.

The mean age of the population was 65.2±10.1 years, and the mean deviation with HFA 24-2 was -3.26±2.6 dB. The mean test duration was not significantly different between the tests (p = 0.13). A CVFD was present in 33 (80.4%) HFA 10-2 test and in 23 (56.0%) Octopus G1 tests (p = 0.002). The overall agreement between the HFA 10-2 and Octopus G1 examinations in classifying eyes as having or not having CVFD was moderate (Cohen's kappa 0.47). The Octopus G1 program showed 69.6% sensitivity and 100% specificity to detect CVFD in eyes where the HFA 10-2 test revealed a CVFD. The number of depressed test points (p<5%) outside the central 10° area detected with the Octopus G1 program (19.68±10.6) was significantly higher than that detected with the HFA 24-2 program (11.95±5.5, p<0.001).

Both HFA 10-2 and Octopus G1programs showed CVFD not present at HFA 24-2 test although the agreement was moderate. The use of a single Octopus G1 examination may represent a practical compromise for the assessment of both central and peripheral visual field up to 30° eccentricity without any additional testing and increasing the total investigation time.