Glaucoma Flashcards
What are Circumlinear Vessels?
Vessels that pass circumferentially across the temporal aspect of the Optic cup.
Essentially the vessel is kinking to follow the cup margin.
What is Baring of Circumlinear Vessels?
If vessels pass through the exposed depths of the cup, they are “bared.”
Baring of circumlinear vessels is seen because as the cup recedes, it exposes the vessel.
What is Glaucoma?
A group of progressive ocular diseases with various aetiologies that ultimately result in consistent Optic Neuropathy and usually with a characteristic loss of Visual Function.
Glaucoma results in irreversible loss of nerve fibres, leading to an appearance of “cupping” or an increased vertical C/D ratio.
Progressive Optic nerve damage with characteristic Visual field changes.
What does Tortuous mean?
Windy blood vessels
What is Arteriovenous Nipping?
A small artery (arteriole) is seen crossing a small vein (venule), which results in the compression of the vein with bulging on either side of the crossing.
What is Bayoneting?
When the local thinning of NRR tissue reaches the Disc margin, a sharpened rim is produced.
If Retinal blood vessels cross this sharpened rim then they will bend or kink sharply.
Bayoneting may be a sign of erosion or loss of the NRR.
Z shape Appearance
What is Notching?
Focal area of loss of NRR tissue
Causes Fly-over Vessels
What is Nasalisation of Vessels?
The Central Retinal Vessels shift Nasally in cases of Progressive Glaucoma.
What is Arteriolar Narrowing?
Characteristic clinical sign of Hypertension.
What is the ISNT Rule a measure for?
Assess the Neural Retinal Rim of the Optic Disc.
In Healthy Eyes the NRR is:
- Thickest Inferiorly
- Thinnest temporally
In Glaucomatous Eyes, there is Vertical Thinning, with Atrophy along the inferior and superior rims.
What is a Temporal Gray Crescent?
Pigment deposited temporally around the Neuro Retinal Rim.
Prevalent - African descent with Glaucoma
Types of Characteristic Visual Field Defects:
- Nasal Step
- Arcuate
- Paracentral
- Overall Depression of the Field in the End stage
First evident within the central 30’
Symptomless until Advanced
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The chance of precipitating an Angle-Closure Glaucoma is __________
1 in 45,000
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4614311/
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Types of Glaucoma -
- Primary Open Angle Glaucoma
- Angle Closure Glaucoma
- Normal Tension Glaucoma
- Secondary Glaucoma
- Congenital Glaucoma
- Pigmentary Dispersion Syndrome
- Psuedoexfoliative Glaucoma
- Traumatic Glaucoma
- Neovascular Glaucoma
- Irido-Corneal Endothelial Syndrome
- Uveitic Glaucoma
POAG
The Trabecular Meshwork become blocked and the fluid accumulation causes pressure to build within the eye.
Uveoscleral Draiange canal is CLEAR.
ACG
The aqueous cannot drain properly because the entrance to the Uveoscleral drainage canal is either too narrow is closed completely and Trabecular Meshwork is blocked.
IOP rises very quickly and can be triggered by pupil dilation.
NTG
Low-pressure Glaucoma
Optic Nerve is damaged even thought the IOP is not excessively elevated.
What does the “Angle” refer to?
The angle the iris makes with the cornea.
Treatment for POAG?
Ocular Hypotensive Drugs to reduce IOP via Prostaglandin Analogues.
Drugs used as a second line of Defence for POAG include:
- Carbonic Anhydrate Inhibitors
- Beta-blockers
- Alpha Agonists
- Cholinergic Agents
Steroid-induced Glaucoma is considered to be a type of _________
Secondary Open-Angle Glaucoma causd by increased resistance to the outflow of aqueous at the level of Trabecular Meshwork.
Treatment for Angle Closure -
Prophylactic Laser Peripheral Iridotomy is opted to treat narrow angles.
A beta-blocker may be used in the treatment of POAG but these drugs are contraindicated for use in persons with chronic obstructive pulmonary disease and heart block.
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Function of Prostaglandin Analogues -
Increase Uveoscleral Outflow to reduce IOP.
Function of Beta-blockers -
Decrease Aqueous Production to reduce IOP.
Function of Alpha-2 Adrenergic Agonists -
Decrease Aqueous Production and Increase Uveoscleral Outflow to reduce IOP.
Function of Carbonic Anhydrase Inhibitors -
Decrease Aqueous Production to reduce IOP.
Function of Parasympathomimetics -
Increase Aqueous Outflow thru the Trabecular Meshwork by means of ciliary muscle contraction and may open the drainage in Angle-closure Glaucoma by stimulating the Iris Sphincter muscle.
What are some Risk Factors for Glaucoma?
- Positive Family History
- Afro-Caribbean Ethnicity
- Pigment Dispersion Syndrome
- Use of Steroids
