1. FIGURE 1. The nGoggle device
WGCSUB-1925
Objective Assessment of the Contrast Sensitivity Function using the nGoggle
Fabio B. Daga1
Yu-Te Wang1,2
Masaki Nakanishi1,2
Nara G. Ogata1
John K. Zao3
Tzyy-Ping Jung2
Felipe A. Medeiros1
1 Visual Performance Laboratory, Department of Ophthalmology, University of California San Diego, La Jolla, CA, United States.
2 Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, California.
3 Department of Computer Science, National Chiao-Tung University, Taiwan.
Contrast sensitivity (CS), defined as the ability to detect small differences in luminance, is one of the most import visual function measures, being strongly related to the ability to perform many daily activities.1,2
Previous reports have documented CS losses in glaucoma patients, even when presenting a relatively good visual acuity.3
In fact, CS is better than visual acuity in predicting many aspects of visual function.2,3 However, assessment of the CS function is generally a subjective and cumbersome task.
Objective measurement of CS has been demonstrated using sweep visual evoked potentials (VEPs).4
The nGoggle (nGoggle, Inc., San Diego, CA) is a portable brain-computer interface for objective assessment of visual function loss. Previous studies have shown that the nGoggle was able to successfully detect visual field loss in glaucoma.5
The nGoggle integrates wearable, wireless, dry electroencephalograms and a head mounted display (HMD), allowing detection of VEPs corresponding to pattern reversal visual stimuli (Figure 1).
In the present study, we implemented modifications in the nGoggle visual function testing protocol and investigated its ability to objectively quantify the CS function.
INTRODUCTION
FIGURE 1. The nGoggle device
FIGURE 2. Experimental procedure for evaluating contrast sensitivity function on nGoggle.
11 subjects (6 glaucoma and 5 healthy patients) were included in the study.
Mean age was 67.7 ± 8.5 years (Table 1).
Pelli-Robson chart mean contrast sensitivity measurement was 1.55 ± 0.27 log units.
nGoggle VEP amplitudes were significantly related to contrast levels (P<0.001) (Figure 3).
There was statistically significant relationship between the nGoggle VEP amplitude and Pelli Robson contrast sensitivity measurements (r=0.38; P=0.012).
RESULTS
To investigate the feasibility of objective assessment of CS using the nGoggle, and to compare its measurements with conventional methods of contrast sensitivity assessment.
PURPOSE
TABLE 1. Demographic and clinical characteristics of subjects included in the study.
Characteristic
Patients (n = 11)
Age, years
67.7 ± 8.5
Gender, n (%) female
3 (37.5)
Race, n (%) African American
1 (10%)
Pelli Robson Contrast Sensitivity
1.55 ± 0.27
All participats had contrast sensitivity assesment using the nGoggle and the Pelli-Robson chart for both eyes.
The visual stimulus presented on the nGoggle consisted of Gabor patches flickering at 10Hz with sweeping contrasts from low to high (0.5, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0 and 96 %) and five different spatial frequencies [0.5, 1.0, 2.0, 4.0, and 8.0 cycles per degree (cpd)] (Figure 2).
Linear mixed models were used to investigate the relationship between nGoggle VEP amplitude and contrast levels, taking into account eyes nested within patients and multiple spatial frequencies.
We also obtained nGoggle VEP amplitude slopes by contrast levels for spatial frequencies of 0.5 and 1cpd. These were the spatial frequencies chosen since Pelli-Robson assesses CS at a spatial frequency of 0.72cpd
The relationship between these slopes and Pelli-Robson chart measurements was investigated using linear regression models.
METHODS
FIGURE 3. The nGoggle mean VEP amplitude as a function of contrast levels with 95% confidence interval.
The nGoggle was able to objectively assess CS and its measurements were significantly associated with conventional metrics.
The portability and objectivity of the nGoggle may facilitate measurements of the CS function in clinical practice.
CONCLUSION
REFERENCES:
Ginsburg AP. Contrast sensitivity and functional vision. Int Ophthalmol Clin 2003; 43: 5–15.Chia EM, Wang JJ, Rochtchina E, et al. Impact of bilateral visual impairment on health-related quality of life: the Blue Mountains Eye Study. Invest Ophthalmol Vis Sci 2004;45(1):71-6.
Owsley C, Sloane ME. Contrast sensitivity, acuity, and the perception of 'real-world' targets. Br J Ophthalmol 1987; 71:
Richman J, Lorenzana LL, Lankaranian D, et al. Importance of visual acuity and contrast sensitivity in patients with glaucoma. Arch Ophthalmol. 2010;128:1576–1582.
Almoqbel F, Leat SJ, Irving E. The technique, validity and clinical use of the sweep VEP. Ophtal. Physiol. Opt. 2008;28: Nakanishi M, Wang Y, Jung T, et al.
Nakanishi M, Wang Y, Jung T, Zao J, Chien Y, Diniz-Filho A, Daga FB, Lin Y, Wang Y, Medeiros FA. Detecting glaucoma with a Portable Brain-Computer Interface for Objective Assessment of Visual Function Loss. JAMA Ophthalmol. Online published on April 27th, 2017.
Commercial Relationships: Fabio B. Daga, None; Yu-Te Wang, None; Masaki Nakanishi, None; Nara G. Ogata, None; John K. Zao, nGoggle (I); Tzyy-Ping Jung, nGoggle (I); Felipe A. Medeiros, Alcon Laboratories Inc (R), Alcon Laboratories Inc (F), Allergan Inc (F), Allergan Inc (R), Allergan, Inc (C), Bausch & Lomb (F), Carl Zeiss Meditec Inc (F), Carl Zeiss Meditec Inc (R), Carl-Zeiss Meditec, Inc (C), Heidelberg Engineering Inc (F), Merck Inc. (F), National Eye Institute (F), Novartis (C), Reichert Inc (R), Reichert, Inc (F), Sensimed (F), Topcon Inc (F), nGoggle (I).
Supported in part by NIH/NEI Grants EY (F.A.M.) EY (F.A.M).