CLINICAL APPROACH AND DIFFERENTIAL DIAGNOSIS (contd) Examine the posterior segment of the eye with an ophthalmoscope.
Pupil dilatation may be required.
In the normal fundus, the disc is pale with a central cup and reddish-brown surrounding retina. Arteries and veins emerge from the optic disc. The macula is darker than the rest of the fundus and lies on the temporal side of the disc. One-third of all retinal fibres arise from the small macular region and pass to the optic nerve head (disc) as the papillomacular bundle. The macula is the region of sharpest vision (cone vision), whereas peripheral vision (rod vision) serves the purpose of perception of movement and directing central/macular vision. The optic nerve head contains no rods or cones and accounts for the physiological blind spot in normal vision. The macular fibres being so functionally active, are the most susceptible to damage and produce a specific defect in the visual field - a scotoma.
Retinal abnormality voith acute impairment of vision
Arteries: narrow - branch occlusion, one vessel absent, embolus may be visualised -»
Retina: pale and oedematous After a few days the macular area becomes cherry red in appearance (Retina thinned here and the choroid shows through.)
An upper arterial branch occlusion is associated with a lower field defect in one eye.
Confirm with visual field examination.
Altitudinal field defect
Altitudinal field defect
Look for embolic source, e.g. carotid stenosis.
Loss of retinal colour (bccomes milky white) and macular blush. -> CENTRAL RETINAL ARTERY
Disc margin blurred sfi"--------Loss of physiological
Jtfpl 'central cup'
Radial streaks and corrugated appearance of the retina Haemorrhages may appear
Papillitis: visual acuity severely affected due to associated inflammation of the optic nerve (retrobulbar neuritis).
Papilloedema does not affect visual acuity (unless the macular area is affected by haemorrhage) although the blind spot is enlarged.
CLINICAL APPROACH AND DIFFERENTIAL DIAGNOSIS (contd)
HYPERMETROPIC patients who have a pale indistinct disc often difficult to differentiate from early papilledema. HYPERTENSIVE RETINOPATHY - superficial haemorrhages and 'cotton wool' exudates.
PSUEUDOPAPILLOEDEMA - 'DRUSEN' - hyaline bodies near the optic disc which raise the disc and blur the margin. This normal variant may be inherited.
Separation of the superficial retina from the pigment layer-RETINAL
Was this article helpful?
This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.