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A. Bruckmann, T. Peters, J. Miltenberger, H. Luedtke, H. Wilhelm, B. Wilhelm; Pupillary Light Reflex in Blind Retinitis Pigmentosa Patients: Investigation Before and After Implantation of a Subretinal Visual Prosthesis. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4584.
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Blindness in degenerative retinal diseases like retinitis pigmentosa (RP) is associated with a lack of common stimulus-response characteristics of the pupillary light reflex (PLR) or an absent light reaction. Novel knowledge about the role of melanopsin ganglion cells in the pupillary light reflex regulation puts this association into question.This matter was investigated systematically with pupillography in blind RP patients during study recruitment for the first clinical pilot trial with a Subretinal Active Multiphotodiode Array (MPDA).
Ten patients suffering from RP with no reproducible light perception were tested during screening, eight of them were included in the RIM trial, seven patients were implanted with the MPDA. Stimulus intensities of 0.36, 4.0, 36.3 lx corneal illumination were applied with an automated infrared video pupillograph (CIP; AMTech, Germany) in darkness. Each examination was performed twice (functional placebo-control with power supply once switched off).Mean of latency and amplitude of the PLR averaged from four complete and reliable pupillograms entered the analysis.
Baseline examination (n=10): no light reflex elicitible for 0.36 lx (lowest stimulus intensity); for 4.0 lx constriction amplitude was 0.13 +/- 0.28 and for 36.3 lx amplitude was 0.47 +/- 0.4 mm. In contradiction to usual physiological findings the visual threshold was inconsistently above the pupillomotor threshold. Pupils sometimes reacted to unseen stimuli. Stimulation of the MPDA was able to elicit pupillary light reflexes.
PLR and its usual dose-response relationship are preserved in blind RP patients to a larger extend than expected. Investigations in blind RP patients may help to better understand the role of melanopsin ganglion cells in man.
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