Table of Contents
Medical history is very important as well as medication, because drugs may be toxic to the eye or precipitate glaucoma. Examination consists of looking at the eyes, comparing the size of the pupils, and looking for any abnormality of shape of the pupils or clarity of the eyes. It is also important to know if pupils respond equally and briskly to light and accommodation, and if the external ocular movements are full. The doctor will probably check visual acuity. Exact previous visual acuity will probably not be on record but note the strength of spectacles if worn. One of the steps is to use the ophthalmoscope to check the anterior segment for discharge, vascular injection, or swelling and make sure the corneal reflection is clear and free of irregularities.
For diagnosis it is extremely important to know if there is blood (hyphema) or pus (hypopyon) in the anterior chamber. In some cases doctor will suspect the cause of blurred vision is a cataract. To get exact diagnosis it is helpful to check the blood pressure and check urine for glucose, examine the pulse for atrial fibrillation, and listen for any carotid bruit.
If the fovea or macula is affected there will be a dramatic loss of vision. Investigation will depend upon what is suspected; it may require urgent (on the same day) referral to an ophthalmologist for slit lamp examination and a definitive diagnosis. Differential diagnosis means it is helpful to divide into unilateral and bilateral, including homonymous, sudden and gradual in onset, and painful and painless. In addition, glaucoma may affect both eyes but usually only one at a time has an acute attack. Giant cell arteritis may affect one eye initially and immediate starting of steroids is essential to protect the other eye, and chemicals or foreign bodies in the eye may be unilateral or bilateral. Unilateral, sudden and painful are often associated with a painful red eye, which could be corneal abrasion or infection, anterior uveitis, traumatic hyphema, or acute glaucoma. There may even be prostration and vomiting as well. Giant cell or temporal arteritis may be associated with a painful or tender head but the eye is not usually painful and there is usually a complete unilateral loss of vision rather than a complaint of blurred vision. Some people get a typical migraine prodrome without a following headache and it is usually unilateral but may progress to be homonymous. Blurred vision can be part of a toxic illness, which is apparent the patient that is pyrexial and unwell. There will probably be a history of welding a number of hours earlier with inadequate protection and often the patient will offer the diagnosis on its own. It is interesting that drugs like steroids and anticholinergics can also have similar effects. Cerebrovascular disease may lead to damage to the visual pathways and optic cortex. Because of that, there may or may not be macular sparing associated with visual disturbance that is often homonymous.