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Show Journal of Clinical Neuro-ophthalmology 13(1): 77-78, 1993. Letters to the Editor To the Editor: Our vision is interrupted several times a second by saccades, during which the visual world sweeps across the retina. It is a remarkable fact that the smeared image of the visual scene generated by saccadic eye movements is not perceived. There may be several processes contributing to this phenomenon. Holt (1) was the first to propose a "central anaesthesia" initiated by eye movements to account for this lack of vision during saccades. However, Volkmann (2) and Volkmann et al. (3) found that the elevation of visual threshold, and the decrease in contrast sensitivity occurring during saccadic eye movements was small, and unlikely to account for the lack of perception of saccadic blur. More important than such saccadic suppression may be an omission of the perception of the smeared image during saccades: saccadic omission. Psychophysical experiments have concentrated on the importance of forward and backward masking effects in saccadic omission. In these experiments a stimulus preceding or following a saccade obscures the smeared image during the eye movement (4). We would like to report an observation that suggests saccadic omission can also occur in the absence of any interaction between visual stimuli. The fortification spectra experienced by two of the authors during attacks of classical migraine are congruous and homonymous. They are cortical phenomena. When large saccades were made in a dark room the fortification spectra were clearly lost for a brief but appreciable period, to appear again in the same position in the visual field. This was confirmed in four migraine attacks. In these experiments perception of fortification spectra was lost during saccadic eye movements in the absence of any change in visual stimulation. This therefore indicates a form of saccadic omission which is linked to the eye movement itself. P. Brown, M.B., B.Chir., M.A., M.D., M.R.C.P. R. Kapoor, M.A., D.M., M.R.C.P. National Hospital for Neurology and Neurosurgery London WC1N 3BG United Kingdom 77 © 1993 Raven Press, Ltd., New York J. Brown, M.B., B.Chir., M.A., M.R.C.P. Physiological Laboratory University of Cambridge Cambridge CB2 3EG United Kingdom REFERENCES 1. Holt EB. Eye-movement and central anaesthesia. Harvard Psychol Stud 1903;1:3-45. 2. Volkmann Fe. Vision during voluntary saccadic eye movements. J Opt Soc Am 1962;52:571-8. 3. Volkmann FC, Riggs LA, Moore RK, White KD. Central and peripheral determinants of saccadic suppression. In: Senders lW, Fisher OF, Monty RA, eds. Eye movements and the hIgher psychological functions. Hillsdale, NJ: 1978:35-54. 4. Campbell FW. Wurtz RH. Saccadic omission: why we do not see a grey-out during a saccadic eye movement. Visual Res 1978;18:1297-303. To the Editor: A 16-year-old girl tried to commit suicide but "only" the intracranial optic nerves were injured. Her parents brought her to me in the hope that something could still be done. I found myself deeply touched and tried to express my feelings in a poem. I know that the Journal does not have a poetry (!) section, but I thought that perhaps you might find a place for the English translation of this poem, just to show the nonmedical aspect of our medical profession. In Vain I am a Doctor In vain I am a doctor The bullet speeding through her brain Blasted the light to nothingness And I Condemned to be her doctor Suddenly Words flee Again and again I postponed The verdict: Life blindness For blind love |
