Open Angle Gluacoma Flashcards
What is glaucoma?
Optic nerve damage caused by a rise in intraocular pressure
What causes raised intraocular pressure?
A blockage in the aqueous humour trying to escape the eye through trabecular network
2 types of glaucoma?
Open angle and closed angle
What contains the vitreous humour?
Vitreous chamber
What chambers are filled with aqueous humour?
Anterior and posterior chamber
Where is the anterior chamber?
Between cornea and iris
What is between the lens and the iris?
Posterior chamber
What produces the Aqueous humour?
Ciliary body
Journey of the aqueous humour?
Flows around iris to anterior chamber where it drains through the trabecular meshwork and into canal of schlemm. From there it enters general circulation
Normal intraocular pressure?
10-21mmHg
Pathophysiology of glaucoma?
The gradual increase in resistance through trabecular meshwork makes it more difficult for the Aqueous humour to flow through the meshwork and exit the eye
What does gradual increase in resistance through trabecular meshwork result in?
The pressure slowly builds within the eye and this gives slow and chronic onset of glaucoma
What does increased intraocular pressure cause?
Cupping of optic disc
What is in the centre of a normal optic disc and what happens to it when there is raised ICP?
Optic cup (Small indent in optic disc) Raised ICP pressure causes cup to become bigger (cupping)
Risk factors for Glaucoma?
Increasing age
Family history
Black ethnic origin
Near sightedness (myopia)
What is myopia?
Near sightedness
Presentation of open angle glaucoma?
Asymptomatic for long time
- Glaucoma affects peripheral vision first (Tunnel vision)
- Gradual onset of fluctuating pain
- Blurred vision
- Halos around light
Types of Investigation for open angle glaucoma?
Non-contact tonometry
Goldmann Applanation tonometry
Fundoscopy
Visual field assessment
Gold standard investigation for open angle glaucoma?
Goldmann Applanation Tonometry
What is non-contact tonometry?
-Commonly used for estimating intraocular pressure
-Shoots a puff of air at cornea and measures corneal response to it
Less accurate but helpful for general screening
What is Goldmann Applanation Tonometry?
Way to measure intraocular pressure
- Involves special device mounted on slip lamp that makes contact with the cornea & applies different pressures to front of cornea
- Accurate
Diagnosis of OAG?
- Goldmann applanation Tonometry (Intraocular pressure)
- Fundoscopy (Optic nerve health)
- Visual Field assessment (check peripheral vision loss)
Aims of management for OAG?
Reduce intraocular pressure
1st line Management of OAG?
Prostaglandin analogue eyedrops (latanoprost)
Other options of management for OAG?
-Beta blockers (Timolol)
Carbonic anhydrase Inhibitors (Topical Dorzolamide)
Sympathomimetics (brimonidine)
Trabeculectomy surgery (If all else ineffective)
Side effects of Latanoprost?
Eyelash growth
Eyelid pigmentation
Iris pigmentation
Causes of glaucoma?
Old age
Myopia
Diabetes
Symptoms of chronic open angle glaucoma?
Loss of peripheral vision
Diagnosis of open angle glaucoma?
- Tonometry
- Central corneal thickness
- Gonioscopy
Clinical signs of open angled-glaucoma?
- Cupping
- Visual filed defect= damage on bottom half of disc=damage to top half of vision
- May or may not have high IOP
