Differentials
Myopia
SIGNS / SYMPTOMS
Difficulty seeing in poor illumination is often noticed when driving at night. Myopia causes distant objects to appear blurry and unfocused, while nearby objects remain in focus. Myopic shift can occur at low levels of light and may be mistaken for night blindness.[30]
INVESTIGATIONS
Eye test will reveal that the patient is myopic and requires a glasses prescription.
Glaucoma
SIGNS / SYMPTOMS
Patient will often be receiving treatment for glaucoma. Patients may otherwise be asymptomatic.
INVESTIGATIONS
Tonometry will reveal raised intraocular pressure. Examination of optic disc shows an increase in optic nerve head cup-to-disc ratio.
Visual field testing is used to detect any visual field loss.
Optic neuropathy
SIGNS / SYMPTOMS
Patients with optic neuropathy often have unilateral loss of vision, impaired colour vision, relative afferent pupillary defect, periorbital pain, optic disc swelling, and other neurological abnormalities.
INVESTIGATIONS
Visual field examination may reveal a central field defect.
Radiological investigation may reveal optic nerve pathology.
MRI findings support the diagnosis of optic neuritis and rule out other causes of optic nerve damage such as compressive neuropathy.
Cataract
SIGNS / SYMPTOMS
Unilateral or bilateral blurring of vision. Often increasing age and associated glare symptoms.
INVESTIGATIONS
Slit-lamp examination will reveal cataract.
Age-related maculopathy
SIGNS / SYMPTOMS
Patients with early age-related maculopathy may experience difficulty seeing in low illumination due to impaired photoreceptor function.[31]
INVESTIGATIONS
Slit-lamp examination will show changes at the macula.
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