The C3 fields analyzer (CFA) is a moderately reliable perimeter preferred by patients to standard perimetry
. While it does not approximate the gold standard, it was sensitive and specific for clinically defined glaucoma (area under the receiving operator characteristic curve=0.77 to 0.86).
Testing the visual field is a vital sign for diagnosing and managing glaucoma. The current gold standard, the Humphrey visual field analyzer (HFA), is large, expensive and can be uncomfortable for some patients. The current study investigated the CFA, a virtual reality
head-mounted visual field testing device, as a possible subjective field test for glaucoma screening and eventually glaucoma monitoring.
Patients and Methods:
The CFA presented stimuli in the same 54 positions as the HFA 24-2 SITA Standard test using a suprathreshold
algorithm approximating an 18 dB deficit. A total of 157 patients (both controls and glaucoma patients) at the Aravind Eye Hospital, Pondicherry, India, were tested with both devices.
The number of stimuli missed on the CFA correlated with HFA mean deviation (r
<0.001), and with pattern standard deviation (r
<0.001). The area under the receiving operator characteristic curve was 0.77±0.06 for mild glaucoma (HFA mean deviation ≥−6 dB) and 0.86±0.04 for moderate-advanced glaucoma (HFA mean deviation <−6 dB). Patients with an 18 dB or worse deficit at a point in the visual field on the HFA failed to see the CFA stimulus at the same position 38% of the time.
While the CFA did not reliably identify deficits that matched the HFA, it was moderately effective at identifying glaucoma subjects. Further refinements to the device will be required to improve point by point testing performance and screening performance.