Abstract
Purpose: :
Standard automated static perimetry utilizes a large field test object (Goldmann III). Because of the redundancy in the visual system, subtle diffuse pathology affecting the visual pathways may yield normal standard automated perimetry (SAP). Lars Frisen has recently introduced the idea of using tiny supra-threshold dot stimuli (Rarebit) to quickly survey visual fields. We have previously demonstrated that Rarebit is particularly sensitive to persistent visual field defects in patients with recovered optic neuritis (ARVO 2004). We undertook a study to determine the effectiveness of Rarebit in recognizing the visual field abnormalities associated with pituitary tumors.
Methods: :
A series of 20 patients undergoing evaluation and treatment of pituitary tumors were subjected prospectively to SAP (24-2 SITA fast) and Rarebit field testing. Visual fields were analyzed for the pattern of defect.
Results: :
The pattern of visual field defects seen on standard automated perimetry could be duplicated by the Rarebit in all cases. In four patients with normal automated perimetry following pituitary treatment, persistent visual field defects could still be seen in the Rarebit indicating subclinical pathology. In one patient a subtle temporal defect was seen in only one eye, but bitemporal defects were seen on Rarebit. Three patients demonstrated diffuse depression on Rarebit not seen on SAP.
Conclusions: :
The use of tiny supra-threshold stimuli may be a sensitive way of looking for residual defects seen in patients with chiasmal syndrome. It is likely that this is also a more sensitive way of looking for subtle residual abnormalities affecting the optic nerve and post chiasmal visual pathways as well. Patients subjectively tend to prefer Rarebit perimetry over SITA Fast automated field testing.
Keywords: neuro-ophthalmology: diagnosis • visual fields