Focused Assessment of the Patient with Visual Loss
History See text: establish if the visual loss was:
Has the patient noticed ‘floaters’ or photopsia? Other neuro-ophthalmic symptoms? Symptoms suggestive of polymyalgia rheumatica/giant cell arteritis (malaise, lethargy, anorexia, weight loss, night sweats, headache, occipital pain, jaw claudication, scalp tenderness)? Other systemic symptoms? Cardiovascular risk factors? Past eye history, for example cataract surgery or previous uveitis; refractive state, myopic or hypermetropic? Past medical history: diabetes? Thyroid disease? Immunosuppression? Connective tissue disease? Drug history Family history Social history, to include occupation and driving status Examination Perform a general examination, with particular attention to heart, blood pressure, carotid and temporal arteries. Eyes
Check the visual acuity using a Snellen chart, in each eye, with the patient wearing their glasses or contact lenses, or looking through a pinhole. If visual acuity is lower than can be measured by the Snellen chart, determine if the patient can count fingers (CF), detect hand movement (HM) or perceive light (PL). Visual fields Visual field respecting the horizontal midline (i.e. superior or inferior defects) are seen with retinal vascular or optic nerve disorders, or glaucoma. Defects respecting the vertical midline represent a neurological lesion such as a stroke or compressive lesions. Central defects are caused primarily by age-related macular degeneration or other macular disease. In macular disease, the patient experiences a positive scotoma, that is, a ‘spot’ in the vision is seen and reported. Conversely, in optic nerve disease a negative scotoma is present, but not reported, that is, the defect is not ‘seen’ by the patient, but can be detected on examination. Amsler grid This is used to assess macular function. The Amsler grid is a 10cm2 grid, split into 5 mm2 squares, with a central dot. The patient should wear their glasses or contact lenses with any reading correction, if worn. Hold the grid at eye level around 33cm away in good lighting. Cover one eye and ask the patient to focus on the central dot with the uncovered eye, then repeat with the other eye. Distortion will be reported if there is macular pathology (age-related macular degeneration or macular oedema). A central scotoma may be detected in optic nerve disease. Colour vision Ask the patient to assess the colour quality of a bright red object (e.g. top of red pen). A relative difference between the eyes indicates pathology affecting the optic nerve (e.g. optic neuritis); the red is desaturated or ‘washed out’ in the affected eye. ‘Swinging flash light’ test to detect a relative afferent pupillary defect (RAPD) Normally, both pupils constrict symmetrically when a bright light is shone into one eye. When the torch is swung to the other eye, the pupils remain the same size. An RAPD is present if the pupil dilates, when the torch is swung to the affected eye. Both pupils constrict when the torch is swung back to the unaffected eye. A positive RAPD indicates severe retinal and/or optic nerve injury in the affected eye. |