[Causes, Diagnosis and Therapy of Negative Dysphotopsia].

Negative Dysphotopsia (ND) is a dark, sometimes rounded bar or shadow in the temporal visual field after uncomplicated cataract surgery that may lead to great patient discomfort. R. Olson called it "the number one troublesome complaint after uneventful cataract surgery". The origin of this phenomena remains uncertain and is discussed conversely in literature. We have found evidence that it may be caused by a slight difference in magnification caused by the new IOL compared to the old crystalline lens. This may lead to a minimal shift of the object space corresponding the blind spot and the larger central vessels so they become visible for a short time after surgery. Until now, no definitive criteria have been published for a proper diagnosis of ND. Based on our experience with 55 patients (77 eyes) with ND, out of 6,031 cataract procedures during the last two years, the following aspects seems to be important: ND is always 1) a disturbing dark shadow in the temporal visual field after cataract surgery and lens implantation. 2) No pathology of the eye can be found to explain this shadow. 3) In most cases, the following points exist in descending order of importance: The patients feel that the ND-shadow is far in the periphery of the visual field, mostly between 60° and 90°; using objective criteria, the shadow is, in reality, mostly between 10° and 25° in the temporal visual field; ND is variable; temporal illumination diminish ND in most patients; the correction of even the smallest refraction diminishes ND in most patients; if the hands of the examiner are placed alongside the patient's head-like blinders-ND will diminish in most cases; in monocular examination ND may diminish. Before surgery, each patient must be informed about dysphotopsia. Therapy is gradually phased in three steps: 1) ND should be explained by showing an image of the retina, saying, that the shadow is not the border of the IOL, but probably the border of the optic nerve and that all patients get used to that within a few weeks. This calms all patients. 2) If ND lasts too long from the point of view of patients, glasses should be tried, even with very moderate refraction, until ND disappears. 3) If patients do not wish to wear glasses, even for a little while, occlusion for some weeks causes ND to disappear. Only 2 of our 77 eyes with ND out of 6,031 cataract procedures required occlusion therapy, revision surgery was not necessary in any case.