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My field of interest is pupil research. I work as an ophthalmologist and so I am interested particularly in the physiology and pathophysiology of the pupil light reflex. My research work takes place at the Pupil Lab of the Centre for Ophthalmology in Tübingen (Germany), under the supervision of professors Barbara and Helmut Wilhelm. My studies were supported by the Marie-Curie-Training Site "Fighting Blindness" of the European Union and by the Jung Stiftung.
In my experiments I mostly use the method of pupil perimetry (campimetry). It allows an objective examination of the visual field by analyzing the pupil light reactions (PLR) to focal light stimuli presented within the 30° visual field. Pupillary constrictions are registered by an infrared video camera. A visual field defect is characterized by a reduced or totally absent PLR.
An objective evaluation of the visual field by means of pupil campimetry can be a great advantage either in patients who are not able to perform standard automated perimetry or in cases suspected of simulation. Our own study provided evidence that pupil campimetry is applicable for differentiating between retinal dystrophy and functional concentric visual field loss, which is the most common feigned visual field defect (Fig.1) [1].
It seems that the pupil is not only controlled subcortically, but the retrogeniculate visual pathway or even the visual cortex seems to be involved in the PLR. However, this assumption has not been generally accepted yet and the anatomy of the pupillary pathway is still waiting for its review. With my experiments I provided further evidence to support this data. I have examined many patients with retrogeniculate damage of the visual pathway by means of pupil campimetry and showed that it is indeed possible to demonstrate visual field defects due to retrogeniculate lesions very well (Fig 2a, b) [2].
Another issue that I am interested in are the “pupillomotor receptive fields”. I have examined the PLR in healthy persons at different locations in the visual field with stimuli increasing in size. Results of this study suggest that pupillomotor receptive fields exist within the pupillary pathway. They show larger diameters than the retinal receptive fields but respect the summation rules valid for the retinal receptive fields (unpublished results).
Recently we became interested in the possibilities of pupillography in the diagnosis of glaucoma. We showed that it is possible to detect significant differences between the PLR of glaucoma patients and healthy subjects by means of pupil campimetry. On the other hand, in this particular study, the sensitivity of the method fell short of being ideal for screening purposes [3]. Nevertheless, pupillary tests offer a new approach in glaucoma diagnosis and their application should be further investigated.
Pupil research is an interesting field in ophthalmology. It offers many possibilities also for future research and I hope to be able to contribute to it.
Department of Ophthalmology