Maria Kolic

Dichoptic multifocal pupillography reveals afferent visual field defects in early type 2 diabetes.

PURPOSE Multifocal pupillographic perimetry was used to examine differences in the visual fields of 23 subjects with early type 2 diabetes (T2D) and 23 age- and sex-matched control subjects. METHODS Independent stimuli were delivered to 44 regions of each eye while pupil responses were recorded with infrared cameras. The stimuli were presented in 8 segments of 30 seconds, and both eyes of each subject were tested twice. The direct and consensual responses provided 88 responses per eye. The diagnostic power of the method was then examined by applying receiver operator analysis to the peak regional contraction amplitudes, time to peaks, and linear combinations of those. RESULTS Dichoptic multifocal pupillography provided response amplitudes with a median z-score of 2.63 +/- 0.26 (SE). The diagnostic performance (expressed as areas under ROC plots) of the eight subjects (32 fields) who had had T2D for at least 10 years was 0.87 +/- 0.06 (mean +/- SE) for response amplitude deviations from normative data, rising to 0.95 +/- 0.04 when between-eye symmetry was considered. Mean pupil size did not have diagnostic power. Comparison of direct and consensual response fields indicated that the observed localized field defects were afferent. CONCLUSIONS Reasonable diagnostic power was obtained, especially for the 16 eyes that had had T2D for more than 10 years, inferring that even in the near absence of visible diabetic retinopathy, some retinal damage had been sustained. This result, if confirmed in a wider group, suggests the that the method may be clinically useful in screening for early damage to the retina in T2D diabetes.

High resolution multifocal pupillographic objective perimetry in glaucoma

PURPOSE The recent development of an objective and noninvasive perimetric technique using pupillary responses to sparse multifocal visual stimuli shows promise for the assessment of visual function in glaucoma. This study assesses the sensitivity and specificity of four variants of dichoptic multifocal pupillographic objective perimetry (mfPOP) with a high-resolution, 40-region/field stimulus. METHODS Nineteen normal subjects and 17 with open-angle glaucoma were tested with four 4-minute stimulus protocols, presented in eight segments of 30 seconds each. Achromatic multifocal stimuli comprised 40 test regions per eye arranged in a four-ring dartboard layout subtending 60° of visual field. Background luminance was 10 cd/m² with active stimulus regions displaying steady or flickered stimuli at 290 cd/m². Stimulus durations were between 33 and 150 ms, mean intervals between presentations to each test region ranged from 1 to 16 seconds. Fixation was monitored in real time. RESULTS Longer mean intervals and durations resulted in better diagnostic performance. Best results were obtained with 150-ms flickered stimuli and a discriminant function that incorporated both amplitude and width of responses: ROC area under the curve 0.86 ± 0.05 (mean ± SE) across all visual field severities, (n = 34) and 1.00 ± 0.00 for moderate and severe fields (n = 10). CONCLUSIONS mfPOP produces separate information on response delay and afferent and efferent defects at every point in the field. The diagnostic accuracy of the 40-region, 150-ms stimulus is comparable to that of commonly used subjective perimeters and encourages further investigation of this technique.

Multifocal Pupillographic Perimetry With White and Colored Stimuli

PurposeWe investigated issues that could impair the capacity of multifocal pupilliographic perimetry to detect visual field damage. Differential blue light absorbance causes between-subject variance so we compared stimuli with differing blue content. We also quantified declining response gain at higher stimulus intensities (saturation), which can reduce sensitivity to changes in the visual field. MethodsIndependent stimuli were delivered to 44 regions of both eyes whereas pupil responses were recorded under infrared illumination. Luminance-response functions were measured at 88 locations for white, yellow, and red stimuli at luminances ranging from 36 to 288 cd/m2. Response saturation was quantified by fitting power functions: Response=&agr;Luminancez, z<1 indicating declining response gain. Experiments were conducted on 2 groups containing 16 and 18 different normal subjects. The second experiment was designed to confirm the results of the first and to include red stimuli. ResultsResponse saturation occurred in all visual field regions: the mean exponents ranged from 0.57±0.01 to 0.74±0.02 (mean±SE), that is up to 30 SE away from an exponent of 1 (no saturation). The stimulus-response functions appeared to be determined by luminance rather than color. Signal to noise ratios and regional visual field sensitivities were similar for all stimulus colors. ConclusionsResponse saturation was a feature of all visual field locations. Stimuli with reduced blue light content produced the same signal to noise ratios as white stimuli. Given that these stimuli would not be affected by variable lens brunescence, they might be preferable for perimetry.

Stimulus Parameters for Multifocal Pupillographic Objective Perimetry

PurposeWe compared the diagnostic power of 10 stimulus variants that assessed the visual fields of both eyes by recording pupillary responses to multifocal stimuli. The 10 variants comprised 6 initial tests, and 4 subsequent variants whose design was informed by the initial results. MethodsTwo study groups containing 16 normal and 22 primary open angle glaucoma subjects, and 15 normal and 20 primary open angle glaucoma subjects had their diagnostic status verified by a slit-lamp investigation, applanation tonometry, 3 forms of perimetry, and Stratus OCT. Stereoscopically arranged displays presented multifocal stimulus arrays having 24 stimulus regions/eye within the central 60 degrees. Pupil responses were recorded by video cameras under infrared illumination. The 10 stimulus conditions varied in presentation rate, duration, stimulus luminance, and flicker rate. Stimuli were 4 minutes in duration, presented in 8 segments of 30 seconds. Up to 15% of the data of a segment could be lost owing to blinks and fixation losses without repeating the segment. ResultsEach recording gave 96 direct and consensual responses/subject. The best performing stimulus method gave a sensitivity of 1.0±0.0 (mean±SE) for moderate and severe glaucomatous fields combined at a false positive rate of 0.05. Median signal to noise ratios for peak response amplitude expressed as t-statistics exceeded 4 for several variants. ConclusionsStimulus delivery rates of about 1 presentation/region/s and test luminance around 150 cd/m2 performed best diagnostically. Unlike automated perimetry, the mfPOP method provides information on response delays and afferent and efferent defects at each region of the visual field.

High‐ versus low‐density multifocal pupillographic objective perimetry in glaucoma

Multifocal pupillographic objective perimetry was compared using 24 and 44 regions per visual field.

Luminance and colour variant pupil perimetry in glaucoma.

This study investigated the diagnostic utility for glaucoma of multifocal pupillographic objective perimetry stimuli targeting different components of the pupillary response: cortically derived colour responses and subcortical luminance responses.

Retinotopic effects of visual attention revealed by dichoptic multifocal pupillography

Multifocal pupillographic objective perimetry (mfPOP) has recently been shown to be able to measure cortical function. Here we assessed 44 regions of the central 60 degrees of the visual fields of each eye concurrently in 7 minutes/test. We examined how foveally- and peripherally-directed attention changed response sensitivity and delay across the 44 visual field locations/eye. Four experiments were completed comparing white, yellow and blue stimulus arrays. Experiments 1 to 4 tested 16, 23, 9 and 6 subjects, 49/54 being unique. Experiment 1, Experiments 2 and 3, and Experiment 4 used three variants of the mfPOP method that provided increasingly improved signal quality. Experiments 1 to 3 examined centrally directed attention, and Experiment 4 compared effects of attention directed to different peripheral targets. Attention reduced the sensitivity of the peripheral locations in Experiment 1, but only for the white stimuli not yellow. Experiment 2 confirmed that result. Experiment 3 showed that blue stimuli behaved like white. Peripheral attention showed increased sensitivity around the attentional targets. The results are discussed in terms of the cortical inputs to the pupillary system. The results agree with those from multifocal and other fMRI and VEP studies. mfPOP may be a useful adjunct to those methods.