Unexplained visual loss
David Kinshuck, from lectures at Congress 2014
- Photopsia...is common, usually originates in retina.
- Colour vision problems, optic nerve.
- test the APD with a neutral density filter, move from one eye to another, a slight defect should increase and be more obvious when the filter is moved from one eye to the other
- cataract does not cause APD
- no APD..no optic neuropathy
- photostress test...test sight, shine light in eye for 10 seconds, sight should return to normal in 10 seconds; takes much longer with macular disease
- Visual fields...look at pattern deviation not grey scale, eg pituitary tumour
- Understand symptoms, careful ophthalmoscopy, unilateral APD
- 55y patient, Crohns disease, saw white as green, erg reduced....vitamin A deficiency.
- normal fundus..enhanced S cone deficiency
- dengue fever, reduced vision...PERG reduced
- 7y, special school, PERG reduced
- night flashes, let sight reduced 6/12, slight colour vision defect, for 2 months,
- erg reduced....autoimmune retinopathy
- blurred vision, spots, floaters, slowly progressive, difficult adjusting to light..suggests retinal problems. Differential includes
- retinopathy: cancer related or autoimmune
- vitamin a