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
- Retina18 "symptoms and signs described by Gass,6 which included photopsias, persistent visual field loss, and potential visual acuity (VA) loss, with minimal or no fundus changes initially and with loss of one or more zones of outer retinal function. "