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Comparison of a New Head Mount Virtual Reality Perimeter (C3 Field Analyzer) With Automated Field Analyzer in
Annamalai Odayappan1, Priya Sivakumar, Sandal Kotawala
1Glaucoma Services (AO), Aravind Eye Hospital, Pondicherry, India; Neuro-Ophthalmology Services (PS), Aravind Eye Hospital, Pondicherry, India; Alfaleus Technology Private Limited (SK), Jaipur, Rajasthan, India; Department of Biostatistics (RR), Aravind Eye Hospital, Madurai, Tamil Nadu, India; Indira Gandhi Govt. General Hospital and Post Graduate Institute (SN), Pondicherry, India; School of Electrical Engineering (PA), Vellore Institute of Technology, Vellore, Tamil Nadu, India; and Aravind Eye Hospital (RV), Pondicherry, India.
Background:
Automated perimetry in neurologically disabled patients is a challenge. We have devised a patient-friendly virtual reality perimeter, the C3 field analyzer (CFA). We aim to assess the utility of this as a visual field-testing device in neuro-ophthalmic patients for screening and monitoring.
Methods:
Neuro-ophthalmic patients and controls were selected to participate in the study between September and December 2018. They randomly underwent either the CFA or automated field analyzer (HFA) first followed by the other in an undilated state. The CFA results were compared with the HFA, and the correlation of the pattern of the field defect was assessed by an independent masked physician.
Results:
In total, 59 eyes of 33 neuro-ophthalmic patients (cases) and another 95 normal individuals (controls) were enrolled. CFA was found to have greater proportion of reliable fields (81.4%) than HFA (59.3%) ( P = 0.009). There were less false negatives ( P < 0.001) and more false positives in CFA ( P < 0.001) among neuro-ophthalmic patients compared with controls. Among neuro-ophthalmology patients, the number of fixation losses was greater with CFA ( P < 0.001), whereas false negatives were greater in HFA ( P < 0.001). On assessing the pattern of the field defects, we found that there was almost 70% correlation of CFA with HFA. Moreover, in classical neurological fields such as hemianopia, the correlation was 87.5%.
Conclusions:
The CFA seems to correlate well with HFA in classic neurological fields such as hemianopias and may serve as an alternative in patients unable to perform a standard automated perimetry. Further developments are currently underway to incorporate threshold testing.
