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Independents' Day


Blurred vision


Refractive errors are very common. Patients with blurred distance or reading vision should be tested on a Snellen chart with glasses, without glasses and with a pinhole. If the acuity improves with a pinhole it is likely that the optometrist can help.


In the elderly, cataracts are the most common cause of blurred vision. They can easily be seen with an ophthalmoscope. Any opacity, most commonly caused by cataracts, will be seen as a dark shadow across the red reflex.


In patients who have had extracapsular cataract extractions, the posterior capsule may thicken about a year or two after surgery. This can be seen by the same technique as described for cataracts. Laser capsulotomy can be performed simply.


In red painful eyes associated with blurred vision, anterior (iritis) or posterior uveitis should be considered. It is usually accompanied by marked photophobia, and is almost always unilateral.


Sudden painless loss of vision is usually vascular in origin. A central or branch vein occlusion is commonly associated with hypertension and glaucoma. It presents with classical flame-shaped retinal haemorrhages.


Central retinal artery occlusion is much less common. It usually produces total unilateral blindness. Early signs are a cherry-red spot at the macula, but this rapidly resolves. Emboli may be seen in retinal vessels.


Choroidal neovascularisation often produces visual distortion in the early stages. Patients will be aware of kinks when they view straight lines. It is due to new vessels growing from the choriocapillaris. These vessels go on to leak into the sub retinal space. In the early stages when the vascular membrane is extrafoveal, laser treatment can be used to arrest or delay the process, but untreated or in subfoveal cases haemorrhages with subsequent fibrous scarring results in loss of central vision. The new treatment of photodynamic therapy is an alternative to laser treatment but is not yet universally available.


Central serous detachments are most common in men in their fourth decade. It presents with mild blurring of central vision reducing the acuity to 6/12. Commonly micropsia (reduced image size) and delayed dark adaptation are present. Ophthalmoscopically there is a shallow circular elevation of the sensory retina. Most cases resolve spontaneously but if symptoms and signs persist over six months and the diagnosis is confirmed by fluorescein angiography, laser treatment may be indicated.


Retinal detachment is rare. It is more common in myopic patients and in patients who have experienced trauma or had cataract extractions. It is often preceded by flashing lights and floaters.


Dry age-related macular disease is the most common cause of blind registration. It causes slow, progressive loss of central vision. Classic signs are hyperpigmentation at the macula with surrounding atrophic areas.

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