Pattern noise (PANO): a new automated functional glaucoma test.

PURPOSE: To present a newly developed visual field device (pattern noise: PANO) designed to be sensitive to glaucoma defects, cost-effective, material-practical and easy to repair and therefore particularly suited for low-income countries, where glaucoma can be highly prevalent (e.g. sub-Saharan Africa). METHODS: This is primarily a descriptive paper, but it also includes a prospective matched case-control pilot study. Hardware, stimulus, target configuration, testing strategy and result sheet are described. The main outcome measure is the contrast level (range 2-64). Targets are composed of bright/dark pixels flickering with 18 Hz and have a size of 5°. Pixel size is approximated to the hill of vision. Average luminance of targets is constant and equals background luminance.The study was performed in the West Region in Cameroon. Twenty eyes of 20 newly presenting patients with glaucomatous optic disc cupping on funduscopy were compared with 20 eyes of 20 normal patients matched in age and laterality of eye. RESULTS: Mean age was 32.9 ± 18.8 years for glaucoma patients and 32.2 ± 15.6 years for healthy subjects. Mean contrast threshold was significantly higher in eyes with abnormal disc (16.2 ± 14.3 vs. 4.4 ± 0.8, P = 0.002). Correlation of mean contrast thresholds and cup-to-disc ratio was significant (r = 0.59; P = 0.006). Average examination time was significantly longer for glaucoma eyes compared to healthy eyes (8.2 vs. 6.1 min, P < 0.001), whereas error rate did not differ (4.8 ± 2.5% vs. 4.1 ± 1.8%, P = 0.33). CONCLUSION: PANO demonstrated visual field defects in patients with glaucomatous optic disc. Defects correlated significantly with glaucomatous optic nerve head morphological alterations. Healthy eyes obtained normal results. More studies are needed to establish PANO.

Comparison of the Automated Pattern-Noise (PANO) Glaucoma Test with the HFA, an FDT Stimulus, and the Fundus Area Cup-to-disk Ratio.

AIM AND OBJECTIVE: To compare the results of a new automated glaucoma test-Pattern-Noise (PANO)-to the Humphrey Visual Field Analyzer-II (HFA), the fundus area cup-to-disk ratio (CDR), and a frequency doubling technology (FDT) stimulus. MATERIALS AND METHODS: This was a prospective study performed in the West-Region of Cameroon. Two hundred and nineteen eyes of 122 adult patients were included with a clinical suspicion of normal-tension or primary open-angle glaucoma and no other major ocular pathology. Eyes were examined with PANO, HFA (24-2 SITA standard), and FDT-stimulus in a randomized order followed by clinical assessment of the CDR. RESULTS: Parametric correlation of the mean contrast threshold of PANO with the mean contrast threshold of FDT-stimulus, total deviation of HFA, and area CDR was 0.94, -0.85, and 0.62, respectively (p < 0.001 for all values). Spatial distribution of sensitivity thresholds is highly correlated (p < 0.001) at all points in the visual field between PANO and HFA. With cut-off values of 3 ± 1 dB for HFA mean deviation and 4 ± 1 for PANO mean contrast threshold and after eliminating borderline cases, PANO's sensitivity was 95% and specificity 60%. The mean patient age was 45.2 ± 15.8 years. Mean thresholds of PANO and FDT-stimulus decreased with increasing age. Mean examination time was 7.1 ± 1.8 minutes for PANO, 5.9 ± 1.3 minutes for HFA, and 4.7 ± 1.3 minutes for FDT-stimulus. The mean percentage of false-positives per examination was 4.95% for PANO, 4.62% (p = 0.025) for FDT-stimulus, and 2.10% for HFA. CONCLUSION: The results showed that PANO was successful in suspecting the presence of glaucoma. Pattern-Noise examination led to findings that were significantly correlated to HFA, FDT stimulus, and area CDR. Some patterns of defect were also correlated. Furthermore, PANO showed a reasonable examination time and error rate. CLINICAL SIGNIFICANCE: Affordable and robust visual field devices are lacking in large parts of the developing world. Comparing them to established methods is a prerequisite to their clinical use. HOW TO CITE THIS ARTICLE: Hannen T, El-Khoury S, Patel R, et al. Comparison of the Automated Pattern-Noise (PANO) Glaucoma Test with the HFA, an FDT Stimulus, and the Fundus Area Cup-to-disk Ratio. J Curr Glaucoma Pract 2021;15(3):132-138.