Eye: Difference between revisions
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=Clinical Conditions= | =Clinical Conditions= | ||
==Cataract== | ===Cataract=== | ||
Opaque [[proteins]] within the lens leads to loss of lens elasticity. These build up in conditions such as [[rubella]], [[Down’s syndrome]], senile degeration, [[diabetes mellitus]] and [[corticosteroid]] therapy. Removal of the lens and replacement with a synthetic plastic one does the trick. | Opaque [[proteins]] within the lens leads to loss of lens elasticity. These build up in conditions such as [[rubella]], [[Down’s syndrome]], senile degeration, [[diabetes mellitus]] and [[corticosteroid]] therapy. Removal of the lens and replacement with a synthetic plastic one does the trick. | ||
==Glaucoma== | ===Glaucoma=== | ||
Normal intra-ocular pressure is 15-20mmHg. If there is an increase in production of aqueous fluid, or a blockage to its outflow, or a space occupying lesion, then this pressure will rise. It impedes bloodflow to the retina, resulting in [[blindness]]. | Normal intra-ocular pressure is 15-20mmHg. If there is an increase in production of aqueous fluid, or a blockage to its outflow, or a space occupying lesion, then this pressure will rise. It impedes bloodflow to the retina, resulting in [[blindness]]. | ||
==Inflammatory lesions== | ===Inflammatory lesions=== | ||
* [[Chlamydia]] can cause trachoma – which can cause blindness | * [[Chlamydia]] can cause trachoma – which can cause blindness | ||
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* There are rare parasitic infections too. | * There are rare parasitic infections too. | ||
==Retinal Ischaemia== | ===Retinal Ischaemia=== | ||
Usually due to the blocking of a [[blood]] vessel from [[atherosclerosis|atheroma]], etc. It causes death or damage to photoreceptive cells in the retina. Most commonly happens in diabetics or hypertensives. Can be seen as yellow retinal lesions in an ophthalmoscope, as can dot and blot haemorrhages. Can lead to neovascularisation, where new vessels form around the lesion – which blocks the photoreceptor cells and leads to a loss of vision. | Usually due to the blocking of a [[blood]] vessel from [[atherosclerosis|atheroma]], etc. It causes death or damage to photoreceptive cells in the retina. Most commonly happens in diabetics or hypertensives. Can be seen as yellow retinal lesions in an ophthalmoscope, as can dot and blot haemorrhages. Can lead to neovascularisation, where new vessels form around the lesion – which blocks the photoreceptor cells and leads to a loss of vision. | ||
==Optic Neuritis== | ===Optic Neuritis=== | ||
Sudden onset of (usually) one sided blurring of vision. Rarely complete loss of sight, and also rarely in both eyes. It occurs due to inflammation of the optic nerve, which swells up the myelin sheaths, sometimes killing them off. Usually returns to normal in a couple of weeks. Most common in [[Multiple Sclerosis]], where it is often the presenting complaint, but also caused by [[infections]] or by [[auto-immune]] conditions. | Sudden onset of (usually) one sided blurring of vision. Rarely complete loss of sight, and also rarely in both eyes. It occurs due to inflammation of the optic nerve, which swells up the myelin sheaths, sometimes killing them off. Usually returns to normal in a couple of weeks. Most common in [[Multiple Sclerosis]], where it is often the presenting complaint, but also caused by [[infections]] or by [[auto-immune]] conditions. | ||
==Tumours== | ===Tumours=== | ||
A large variety of [[tumour|tumours]] can form in the eye, although generally, if a primary, recovery rates are fairly good on removal of the eye. | A large variety of [[tumour|tumours]] can form in the eye, although generally, if a primary, recovery rates are fairly good on removal of the eye. | ||
Revision as of 08:06, 27 March 2008
Anatomy & Physiology
Structure
Function
Clinical Conditions
Cataract
Opaque proteins within the lens leads to loss of lens elasticity. These build up in conditions such as rubella, Down’s syndrome, senile degeration, diabetes mellitus and corticosteroid therapy. Removal of the lens and replacement with a synthetic plastic one does the trick.
Glaucoma
Normal intra-ocular pressure is 15-20mmHg. If there is an increase in production of aqueous fluid, or a blockage to its outflow, or a space occupying lesion, then this pressure will rise. It impedes bloodflow to the retina, resulting in blindness.
Inflammatory lesions
- Chlamydia can cause trachoma – which can cause blindness
- Bacterial infections can cause glaucoma (see above)
- Viral infection from herpes simplex can cause problems.
- There are rare parasitic infections too.
Retinal Ischaemia
Usually due to the blocking of a blood vessel from atheroma, etc. It causes death or damage to photoreceptive cells in the retina. Most commonly happens in diabetics or hypertensives. Can be seen as yellow retinal lesions in an ophthalmoscope, as can dot and blot haemorrhages. Can lead to neovascularisation, where new vessels form around the lesion – which blocks the photoreceptor cells and leads to a loss of vision.
Optic Neuritis
Sudden onset of (usually) one sided blurring of vision. Rarely complete loss of sight, and also rarely in both eyes. It occurs due to inflammation of the optic nerve, which swells up the myelin sheaths, sometimes killing them off. Usually returns to normal in a couple of weeks. Most common in Multiple Sclerosis, where it is often the presenting complaint, but also caused by infections or by auto-immune conditions.
Tumours
A large variety of tumours can form in the eye, although generally, if a primary, recovery rates are fairly good on removal of the eye.