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Simultaneous Multifocal Pupillographic Visual Field Assessment of Both Eyes

May 26, 2009 in Conference, Poster

World Glaucoma Congress 2009, Boston MA, 8-11 July 2009

Authors

T. Maddess(1), M. Kolic(1), RW Essex(2), A.C. James(1).
(1) ARC Centre of Excellence in Vision Science, Australian National University, Canberra, Australia.
(2) Dept. Ophthalmology, Australian National University, Canberra, Australia.

Purpose

To investigate the diagnostic power and repeatability of 8 variants of multifocal pupillographic perimetry in open angle glaucoma.

Design

Experimental design.

Participants

Eight stimulus protocols were examined in two blocks of experiments. Block 1 contained 40 normal and 39 glaucoma subjects; block two: 41 normal and 47 glaucoma subjects. Diagnosis was confirmed by examining all subjects with HFA achromatic, and Matrix 24-2 perimetry, Stratus OCT, slit lamp and tonometry. Informed written consent was obtained from all subjects under ANU ethics approval 238/04.

Methods

Independent multifocal stimuli were presented concurrently to both eyes with a dartboard layout, having 44 independent test regions/eye extending to 30 deg eccentricity. The recording duration for 5 protocols was 4 min., divided into 8 segments of 30 s each, and for the other 3 was 6 min. divided into 9 segments of 40 s. Stimuli in each protocol could differ in the presentation rate per stimulus region (0.25, 1, presentations/s), or luminosity (150, 180, 290 or 340 cd/m²). Background luminance was 10 cd/m². Since both pupils responded to stimuli from both eyes, 88 responses/eye were obtained giving 176 contraction amplitudes and 176 delays per protocol, with SE for all 352 measures. Retest was done within 4 weeks. Visual fields were classified by HFA mean defects: moderate: 6 to 12 dB, severe: >12 dB.

Main outcome measures

The relative diagnostic power of the 8 protocols was examined using areas under receiver operator plots (AUC). The signal qualities were quantified as the median t-static across regions and subjects for peak (relative) constriction amplitude. Test-rest quality was quantified by the width of the 25th to 75th and 5th to 95th percentiles on plots of visit 1 versus visit 2 defects.

Results

In Block 1 for severe fields the mean of the 20 regional amplitudes that most deviated from the normative data gave an AUC of 0.98 ± 0.01 (mean ± SE), and for combined moderate and severe fields 0.86 ± 0.04. The median t-stat for that protocol was 2.79 ± 0.29. That protocol had a mean presentation rate of 0.25/s and luminance of 150 cd/m2. These results were reproduced in Block 2 and a 6 min. version of the best protocol of Block 1 had a median t-stat of 3.26 ± 0.45, with a concomitant improvement in test-test variability.

Conclusions

This study indicates that multifocal pupil perimetry can yield acceptable diagnostic power, excellent median signal quality and test-retest variability comparable to the Matrix perimeter using a test duration equivalent to 3 min/eye. Data on efferent and afferent defects is obtained for all regions and data from blinks and fixation losses are automatically discarded. That protocol had a mean presentation rate of 0.25/region/s and luminance of 150 cd/m2. These results were reproduced in Block 2 and a 6 min. version of the best protocol of Block 1 had a median t-stat of 3.26 ± 0.45, with a concomitant improvement in test-test variability.

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World Glaucoma Congress 2009 – Booth 28

February 17, 2009 in Conference

World Glaucoma Congress 2009, Boston MA, 8-11 July 2009.

Come and see The TrueField Analyzer (TFA) at this year’s WGC meeting in Boston – Booth #28 (see map below).

Dr Ted Maddess will also present a poster about the TFA entitled:

Simultaneous Multifocal Pupillographic Visual Field Assessment of Both Eyes.

Be sure to come and speak to the TFA team at the meeting – we look forward to seeing you there!

WGC 2009 Exhibit Hall Floor Plan

Concurrent binocular multifocal pupillographic field testing

July 18, 2007 in Conference, Poster, Publication | No comments

Poster #77. World Glaucoma Congress, Singapore, 18-21 July 2007

Authors

AC James, T Maddess. ARC Centre of Excellence in Vision Science, Australian National University, Canberra, Australia.

PURPOSE

This study was a preliminary investigation of a means of concurrently assessing the visual fields of both eyes by recording the responses of both pupils to independent stereoscopically presented multifocal stimuli, to investigate the sensitivity and specificity of this as a method for objective perimetry for glaucoma.

DESIGN

Experimental design.

PARTICIPANTS

The 20 normal subjects were given a thorough eye exam including HFA achromatic 24-2 fields (SITA) and fundus photography assessed by a single skilled observer. The 26 open angle glaucoma patients had stable, moderate to severe, HFA fields. Subjects were age and sex matched. All subjects gave written consent in accordance with the Helsinki Declaration and ANU Human Ethics Protocol 238/04.

METHODS

Dichoptic stimulation was provided via a pair of stereoscopically arranged LCD displays. The subject thus saw a single cyclopean stimulus. Each display presented a circular dart-board-like array of 24 stimulus regions extending to 30 deg eccentricity. Each region in each eye received independent stimulus presentations at a mean rate of 1/s. Four stimulus presentation conditions were tested: each stimulus region containing either a single or a 2×2 array of patches, being presented either steady for 133ms or flickered half-on half-off at 15 Hz for 266ms. For each of the 4 tests the recording duration was 4 minutes, divided into 8 segments, or 2 minutes per eye.

MAIN OUTCOME MEASURES

Sensitivities and specificities for each of the 4 stimulus protocols as obtained from receiver operator plots.

RESULTS

Both pupils were recorded with 24 regions mapped in each eye, giving a total of 96 responses measures/subject from each 4 minute record.The regressive analysis method meant that about 10% of each record could be lost due to blinks etc. without affecting accuracy, e.g.[11,12]. The median peak contraction amplitudes expressed as z-scores for the 4 conditions were 4.1, 3.3, 3.2 and 2.3. The best diagnostic performance was obtained by taking the mean of the 10 worst deviations from the normal profile across the visual field regions, providing a joint sensitivity and specificity of 85% for the flickered single patch condition.

CONCLUSIONS

The pupillographic multifocal method provided diagnostic accuracy that approached that of standard perimetry even though the raw test time was equivalent to 2 min per eye. Measuring the visual fields of the two eyes concurrently has statistical advantages for comparing the two eyes. Unlike perimetry the method provides both sensitivity and temporal dynamics for each visual field region. Unlike evoked potential based multifocal methods pupillography requires no additional setup time for electrode placement. Further experiments also presented at this meeting indicate that with modification of the stimulus parameters can improve sensitivity and specificity.

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Simultaneous pupillographic multifocal visual field assessment of both eyes

July 18, 2007 in Conference, Poster, Publication | No comments

Poster #75. World Glaucoma Congress, Singapore, 18-21 July 2007

Authors

T Maddess, AC James. ARC Centre of Excellence in Vision Science, Centre for Visual Sciences, Australian National University, Canberra, Australia.

PURPOSE

To investigate the sensitivity and specificity of 10 variants of
multifocal pupillographic perimetry in the diagnosis of open angle
glaucoma.

DESIGN

Experimental design.

PARTICIPANTS

Ten stimulus protocols were examined in two blocks of
experiments. Block one contained 22 normal and 23 glaucoma subjects;
block two: 20 normal and 20 glaucoma subjects. Disease state or status
as a normal subject was confirmed by examining all subjects with HFA
achromatic, SWAP and Matrix 24-2 perimetry, Stratus OCT, slit lamp and
tonometry. Informed written consent was obtained from all subjects
under ANU ethics approval 238/04.

METHODS

In all ten protocols independent multifocal stimuli were
presented concurrently to both eyes with a dartboard layout, having 24
independent test regions/eye extending to 30 deg eccentricity.
The test recording duration for each of the 10 protocols was 4 minutes,
divided into 8 segments of 30 s each. Stimuli in each protocol could
differ in the presentation rate per dartboard region (0.25, 1, 4
presentations/s), stimulus duration/presentation (66, 133 or 266 ms),
flicker rate on each presentation (0, 15, or 30 Hz) or luminosity (80, 150
and 290 cd/m²). Background luminance was 10 cd/m². Since both pupils
responded to stimuli from both eyes, 48 responses/eye were obtained
giving 96 contraction amplitude and 96 delays each 4 min test.

MAIN OUTCOME MEASURES

The relative diagnostic accuracies of the
10 protocols were examined using sensitivities and specificities derived
from receiver operator plots. The simultaneously highest sensitivities
and specificities, often called the accuracies, are presented in this
abstract.

RESULTS

Table 1 (far right) gives percent accuracies (Right 2 columns)
illustrating that the best performance was obtained at, shorter
presentation durations, and the highest presentation rates, flicker rates
and luminances. The right-most column labelled amplitude + delay
shows accuracies for a linear discriminant model combining these
measures from each visual field region. The top two Table rows show
outcomes for the best non-flickered and flicked stimuli from the first
block of 6 protocols (Table row 2). The bottom 4 rows of the Table show
outcomes for the 4 protocols of block 2.

CONCLUSIONS

In agreement with a previous study on 20 normal and
26 glaucoma subjects reported at this meeting, flickering stimuli could
achieve quite high sensitivities and specificities. This study indicates
higher presentation and flicker rates combined with higher luminance
stimuli can yield sensitivities and specificities around 95% for test
durations equivalent to 2 min/eye. Our recent advance in multifocal
methods permit these short test durations (11,12).

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