WIANTITAIVE ANALYSIS OF VISUAL FIELD CHANGES IN PITUITARY TUMOURS
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Fifteen patients were studied. They complained of visual troubles and proved to suffer pituitary adenoma. Propertive visual field loss in each quadrant as well as whole field loss were analysed. Tumour volume was determined from C.T. scan by summing serial axial sections. Postoperative infranasal field recovery was significantly greater in patients with tumour volume less than 5 cm. The tumour volume is a poor indicator of postoperative visual field recovery. Visual field loss is the only neuro ophthalmological manifestation of pituitary adenomas with suprasellar extension due to optic nerve compression, chiasnnal compression or both (Moller, Hvid, 1970). The anatomic relation between the diaphragma sellae and the anterior visual pathway suggests that tumours greater than 10 mm above diaphragma is necessary for compressing the anterior visual system. (Findlay et al., 1983). Quantitative assessment of pre and post operative visual recovery showed limited success (Laws et al., 1977). The duration of symptoms, severity of preoperative visual loss, presence or absecns of optic atrophy and the age of the patient are the major preoperative factors that affect the predictivity of visual field recovery (Symon et al., 1979). Also the presence of pre or postfixed chiasma, the exact position of the tumour in relation to the chiasma, dehescence of the diaphragma sellae and vascularity of the tumour play a role in determining visual field recovery. The size of the tumour and the degree of suprasellar extension are measurable factors that can determine the preoperative visual field loss and the postoperative field recovery. However, conflicting data on the correlation of tumour size and visual recovery exists (Synnon, and Jakubowski, 1979).