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How robust is the optic chiasm? Perimetric and neuro-imaging correlations
1Institute of Neuroscience and Physiology, Section of Neurological Sciences and Rehabilitation, and Institute of Clinical Sciences, Section of Radiology, The Sahlgrenska Academy, Göteborg University, Sweden. lars.frisen@neuro.gu.se
Acta Neurologica Scandinavica
|September 18, 2007
Summary
Pituitary adenomas can displace the optic chiasm, affecting vision. Even slight chiasm elevation correlates with visual field defects, with higher elevations significantly increasing the likelihood of vision loss.
Area of Science:
- Ophthalmology
- Neurology
- Radiology
Background:
- Pituitary adenomas frequently cause mass effect on the optic chiasm.
- Understanding the relationship between optic chiasm deformation and visual field deficits is crucial for patient management.
Purpose of the Study:
- To analyze the relationship between tumor-induced optic chiasm dislocations/deformations and visual function.
- To correlate imaging findings with perimetric data in patients with pituitary adenomas.
Main Methods:
- Magnetic resonance tomography (MRT) and two quantitative computerized perimetry methods (High-pass Resolution Perimetry - HRP, and RareBit perimetry - RBP) were used.
- 31 patients with pituitary adenomas impinging on the optic chiasm were evaluated prior to treatment.
Main Results:
- Perimetric abnormalities varied from none to moderate.
- HRP detected abnormalities in 10 cases, RBP in 15 cases.
- Field defects correlated well with the degree of chiasm deformation and dislocation, with cranio-caudal position being a key indicator.
Conclusions:
- An average chiasm elevation of 6 mm is associated with a 50% incidence of visual field defects.
- A further 5 mm elevation increases the incidence of visual field defects to 90%.
