Patients whose eyes become misaligned may report blurred vision when they are really experiencing double vision; if covering either eye makes blurred vision disappear, it probably is double vision!
Step 2:
perform the pinhole test;
if it improves visual acuity, the patient probably has an uncorrected refractive error or ocular media imperfection
Step 3:
perform refraction and biomicroscopy to confirm an optical cause; if you do not find an optical cause …
Step 4:
perform the swinging flashlight pupil test,
looking for a relative afferent pupil defect (RAPD), which would suggest an optic neuropathy or extensive retinopathy
Step 5:
perform
ophthalmoscopy
to exclude optic disc or macular abnormalities, most of which will be visible;
if the diagnosis remains uncertain…
Step 6:
perform a formal visual field examination
to establish the pattern of visual field loss, which may localize the lesion to the retina, optic nerve, optic chiasm or retrochiasmal visual pathway;
if the diagnosis remains uncertain…
Step 7:
perform ancillary studies, such as optical coherence tomography (OCT), fundus photography, fluorescein angiography, ultrasonography, electroretinography (ERG), or orbit/brain imaging
Pinhole, refraction, and biomicroscopy will diagnose most optical conditions
Ophthalmoscopy will diagnose most retinal conditions, but OCT and ERG improve sensitivity
History and visual field examination are helpful in localizing lesions of the retinocortical visual pathway, but brain imaging is often needed for diagnosis
Many conditions causing acute binocular visual loss require prompt treatment to prevent catastrophic outcomes
Some chronic conditions (refractive error, cataract, keratopathy, certain optic neuropathies) can be effectively treated
