Analysis of retinal function using chromatic pupillography in retinitis pigmentosa and the relationship to electrically evoked phosphene thresholds.
OBJECTIVE
To analyse pupil responses to specific chromatic stimuli in patients with advanced retinitis pigmentosa (RP) to ascertain whether chromatic pupillography can be used as an objective marker for residual retinal function. To examine correlations between parameters of the pupil response and the perception threshold of electrically evoked phosphenes.


METHODS
Chromatic pupillography was performed in 40 patients with advanced RP (visual acuity < 0.02 or visual field ≤5°, non-recordable ERGs) and 40 age-matched healthy subjects. Pupil responses to full-field red (605 nm) and blue (420 nm) stimuli of 28 lx corneal illumination were recorded and analysed for two stimulus durations (1 and 4 seconds). The perception threshold of phosphenes to transcorneal electrostimulation was ascertained and correlated to the pupil responses and visual acuity.


RESULTS
Patients with RP showed significantly reduced pupil responses to red and blue stimuli compared with the controls. With red stimuli, pupillary escape could be observed; blue stimuli resulted in a well-preserved postillumination pupil response. Phosphene thresholds were significantly increased in patients with RP and correlated with the parameters of the pupil response if all subjects were considered. Within the RP group alone, this relationship was less pronounced and statistically not significant.


CONCLUSIONS
Chromatic pupillography demonstrated a significant decrease in outer retinal photoreceptor responses but a persisting and disinhibited intrinsic photosensitive retinal ganglion cell function in advanced RP. These phenomena may be useful as an objective marker for the efficacy of any interventional treatment for hereditary retinal diseases as well as for the selection of suitable patients for an electronic retinal implant.
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
Carina
C
Kelbsch
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.|Department of Orthoptics and Visual Sciences, Faculty of Medical Technology, Niigata University of Health and Welfare, Niigata, Japan.
Fumiatsu
F
Maeda
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.|Medical University of Bialystok, Bialystok, Poland.
Jolanta
J
Lisowska
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.|Medical University of Bialystok, Bialystok, Poland.
Lukasz
L
Lisowski
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.|Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
Torsten
T
Strasser
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.|Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
Krunoslav
K
Stingl
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
Barbara
B
Wilhelm
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
Helmut
H
Wilhelm
Pupil Research Group at the Centre for Ophthalmology, University of Tübingen, Tübingen, Germany.
Tobias
T
Peters
D003315:Cornea; D003941:Diagnostic Techniques, Ophthalmological; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D012025:Reflex, Pupillary / Q000502:physiology*; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000503:physiopathology*; D014792:Visual Acuity
chromatic pupillography; electrically evoked phosphene threshold; ipRGC; retinitis pigmentosa