Dichoptic multifocal pupillography reveals afferent visual field defects in early type 2 diabetes
Andrew Bell 1*,
Andrew Charles James 2,
Maria Kolic 3,
Rohan W Essex 4,
and
Teddy Maddess 5
1 Visual Sciences, Australian National University, PO Box 475, Canberra, Australian Capital Territory, 2617, Australia
2 Research School of Biological Sciences, Centre for Visual Sciences, Canberra City, Australian Capital Territory, Australia
3 Seeing Machines, Canberra, Australian Capital Territory, Australia
4 Ophthalmology, The Canberra Hospital, Canberra, Australian Capital Territory, Australia
5 ARC CoE in Visual Sciences & CVS, Australian National University, Canberra, Australian Capital Territory, Australia
* To whom correspondence should be addressed. E-mail: andrew.bell{at}anu.edu.au.
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Abstract |
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PURPOSE: Using multifocal pupillographic perimetry, we examined differences in the visual fields of 23 subjects with early type 2 diabetes (T2D) and 23 age- and sex-matched controls.
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 s, and both eyes of each subject were tested twice. The direct and consensual responses provided 88 responses/eye. We then examined the diagnostic power of the method 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) for the 8 subjects (32 fields) having 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 the observed localised 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 method may be clinically useful in screening for early damage to the retina in T2D diabetes.
Key Words:
diabetic retinopathy, pupils, automated perimetry, retinal degeneration
