Fortschritte der Ophthalmologie : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft
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In a study of 280 patients (265 with cataract, 15 with strabismus), we investigated the ocular circulatory effects of 3 methods of anesthesia widely used in ophthalmic surgery, retrobulbar, peribulbar and general anesthesia. Retrobulbar anesthesia (RETRO) was performed with 2, 5 or 8 ml of a mixture (BLH-Mix) of bupivacaine 0.75%, lidocaine 2% and hyaluronidase; with 5 ml BLH-Mix and addition of adrenaline in a low (1:500,000) or a higher (1:200,000) concentration; with 5 ml bupivacaine 0.75% or lidocaine 2% or mepivacaine 2%; with 5 ml mepivacaine 2% and addition of 150 units hyaluronidase; or with 5 ml BLH-Mix plus adrenaline and additional oculopression. Peribulbar anesthesia (PERI) was performed with 8 ml BLH-Mix (5 ml inferotemporally/3 ml superonasally) or 10 ml BLH-Mix (8/4) injected outside the muscle cone. General anesthesia was performed using halothane (inspiratory concentration 0.5 vol%) and nitrous oxide (65 vol%); respiration was adjusted to produce slight hyperventilation (alveolar pCO2 33 mmHg) or forced hyperventilation (pCO2 20-25 mmHg), respectively. The following variables were measured; systolic ciliary perfusion and blood pressures (PPs,cil and Ps,cil, respectively) and ocular pulsation volume (PVoc) using oculo-oscillodynamography of Ulrich, and the intraocular pressure (IOD) using the Draeger handapplanation tonometer. ⋯ The anesthesia-induced lowering of both ocular perfusion and blood pressures as well as of the ocular pulsation volume, which is a measure of the pulsatile choroidal blood flow, can be interpreted as reflecting an inhibitory influence on ocular circulation. We suggest the following mechanisms to account for the changes during LA: elevation of IOP, adrenaline-induced retrobulbar vasoconstriction, LA-induced retrobulbar vasoconstriction (hypothetical), improved penetration of LA brought about by the orbital compression occurring during oculopression. The relative significance of the separate mechanisms differs, however, between the various LA types. The changes found during general anesthesia are attributable to the halothane-induced reduction of systemic blood pressure and cardiac stroke volume as well as to a relative hyperventilation-induced choroidal vasoconstriction. The results are relevant for ophthalmic surgery with respect to the prevention of complications and problems depending on pathologic or at least unphysiological changes in ocular circulation, e.g...
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Uni- or bilateral dilatation of pupils that are not reactive to light and lack miosis in response to 1% pilocarpine may be caused by contact with plants containing alkaloids such as scopolamine and atropine. Other causes of a non-light-reactive dilated pupil, such as Adie's tonic pupil, third nerve palsy and lesion of the mesencephalic pretectal region, must be excluded before testing the iris sphincter reaction to 1% pilocarpine. Among the naturally growing flowers in Germany, deadly nightshade (Atropa belladonna), jimson weed (thornapple, Datura stramonium) and black henbane (Hyoscyamus niger) contain enough alkaloids to cause mydriasis by direct contact. ⋯ These plants can grow very large and are often planted in tubs. They have to be cut back each year before the winter. This is typically how the eye is contaminated by parts of the plants, which can cause dilatation of the pupil mimicing a neuroophthalmological disorder.