I’ve had a few patients referred to me for subjective complaints of visual field constriction, worse temporally, which progressively worsens over time. The complaint is often expressed as a comparison between the excellent vision they had in their youth compared to where it is now. It is painless and is often described as progressive.
The concern with bitemporal visual field constriction, of course, often results in neuroimaging to look for a pituitary tumor or some other lesion that affects the optic chiasm, even if the automated perimetry appears to be normal. But what happens if the MRI or CT is normal?
The first step should be to examine the images yourself. You never know if a chiasmal lesion is missed if you don’t look at the scans yourself.
But if the MRI/CT is truly normal, it seems that the progression in referrals tends to lean either towards Retina (to rule out retinal detachment), or to Neuro-Ophthalmology (for unexplained vision loss). I think this is appropriate. But what happens if those exams are completely normal?
This tidbit from Walsh’s Visual Field text may be helpful to explain to patients when the entire workup for their subjective visual field constriction is normal (this is of course assuming the appropriate age, normal visual fields, and completely normal workup):
The temporal field constricts with age after the sixth decade of life. This constriction may be due partly to age-related miosis but is more probably due to decreased oxygenation of the peripheral retina with age. Oxygen concentration has been reduced experimentally during field measurements. Peripheral loss was reported by dive-bomber pilots during World War II; they noticed peripheral loss as they went into power dives and increased the G forces, reducing the oxygenation of the head.
Thomas J. Walsh
I think that it is still appropriate to work up patients >60 yo with complaints of temporal peripheral vision loss to rule out chiasm disease. But perhaps we don’t have to fret as much if the fundus is normal and the brain scan is normal.
Reference
Walsh TJ, ed. Visual Fields: Examination and Interpretation. Third Edition. New York: Oxford University Press, 2011: 6.