Key physical examination features in monocular vision loss
| Physical examination | Helpful techniques | Results |
|---|---|---|
| Visual acuity | Vision screening apps (eg, EyeChart Vision Screening App by Dok LLC) Use corrective lens or pinhole occluder | Pinhole test corrects refractory error by permitting central rays of light into the eye; will not correct underlying neurologic impairment |
| Visual field | Monocular assessment Confrontation visual field testing uses small-amplitude finger movements in all quadrants Central fields tested by Amsler grid | Scotoma: discrete area of visual impairment surrounded by intact vision; positive scotoma (seeing something that is not there) may be a sign of retinal damage; negative scotoma may indicate optic nerve dysfunction Hemianopia: bilateral visual impairment suggesting a lesion posterior to optic chiasm |
| Color testing | Use red objects (sharps container or bottle cap) | Unilateral color desaturation: optic nerve dysfunction |
| Pupillary examination | Examine for size, shape, symmetry Swinging flashlight examination: paradoxical dilation when stimulating ipsilateral eye after shining light into contralateral eye | Afferent pupillary defect: optic nerve dysfunction |
| Red reflex | Performed with ophthalmoscope when standing 1 foot away from patient | Loss of reflex: localizes to media and possibly retinal detachment |
| Direct ophthalmoscopy | Use dilating drops to enhance the examination Disc: neuroretinal fibers entering the eye Macula: located temporally to disc and lacking blood vessels | Cherry red macula: ischemic retina from central retinal artery occlusion that contrasts with nourished macula supplied by posterior ciliary arteries Hollenhorst plaque: cholesterol emboli signifies atherosclerotic disease in carotid or aortic arch Pale and swollen optic nerve head: ischemic optic neuropathy from posterior ciliary artery obstruction |
Information from references 2 and 3.