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). |
