Elevated arterial carbon dioxide tension, induced by the administration of CO2 via the respiratory air or by hypoventilation, entailed a gradual increase in the IOP in patients without eye diseases under general anaesthesia. A sudden cessation of CO2 administration or hyperventilation caused such a rapid, simultaneous fall in IOP to values below the initial level that the pressure variations must be of vascular nature, presumably related to changes in choroidal blood volume. The above-mentioned procedures always cause a change in the central venous pressure (CVP) simultaneously with the IOP changes. Alterations of the CVP induced by hydrostatic factors in postural changes, placing the head 15 degrees above or below the horizontal level while keeping the PaCO2 constant, caused IOP changes of the same configuration and magnitude as described above. It is concluded, therefore, that presumably the CO2-conditioned IOP changes are due predominantly to changes in central venous pressure, being one link in a CO2-conditioned action upon the general circulation, entailing passive secondary changes in the choroidal venous blood volume and thereby an influence upon the IOP. On the basis of the present results it appears rational to recommend hyperventilation to keep the PaCO2 between 25 and 30 mm and a 15 degree anti-Trendelenburg position in operations on the eye under general anaesthesia, since both procedures afford a low central venous pressure and consequently a low pressure in the posterior segment of the eye, with its attendant advantages as regards vitreous complications and the insertion of intraocular lenses. Owing to the risk of an unacceptable fall in BP in the combined procedure, a frequent checking of the BP is needed.
Periphlebitis retinae (PR) in multiple sclerosis (MS) is seen as transitory infiltrations around veins in the otherwise normal retina. Cellular infiltrations have been found around veins in the central nervous system (CNS), where it has been suggested that they are the first event in plaque formation. Technetium brain scans are usually normal in MS patients, but transitory abnormal scans of the cerebrum have been found in MS patients during acute attack or exacerbation. In order to test the hypothesis that active PR is a sign of simultaneous disease activity in the CNS, 29 technetium brain scans were carried out on 14 MS patients with active PR and on 15 MS patients without any signs of PR. Significantly more of the patients with active PR, compared with MS patients with previous PR, displayed abnormal brain scans. This indicates that a disruption of the blood brain barrier (BBB) and active PR occur simultaneously in MS.
Seventy-one consecutive patients who underwent operation for senile cataract in both eyes during the period 1969-1973 were examined and questioned about visual complaints an average of 18 months after being fitted with cataract spectacles. In the distance situation none had complaints, either reported spontaneously or after questioning. Except for a few immobile patients, all could manage on their own in the street and on stairs. In the near situation 16 of the 71 patients had permanent alternating or intermittent exotropia which, however, gave rise to diplopic complaints in only two. The diplopia in these two patients disappeared after the glasses had been decentered. On questioning, complaints of diplopia could be elicited in another 5 patients. Investigation of sensory binocular function using Titmus' sterotest showed that 35 of the 71 patients could manage the test at the level 40 inches/arc. Division of the material into two groups by duration of monocular visual function during the development of the cataract and during the period between the operations on the two eyes, disclosed that this factor was of no importance to the postoperative motor and sensory binocular function.
Periphlebitis retinae (PR) in multiple sclerosis (MS) is defined as ophthalmoscopically visible cuffs around veins in the otherwise normal retina. PR in MS has been suggested to be of a recurring nature, but to the authors knowledge this is the first study in which PR in MS has been seen to recur. A recurrence of PR in MS reflects the neurological progress. The material is unique because of the span of years these patients have been followed. In the 4 patients here presented the interval between the two episodes of PR was 16, 13, 5 and 0.5 years, respectively.
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