1. Introduction and Glaucoma Flashcards
Draw the Visual Pathway
Insert Image
What constitutes the visual pathway?
Optic nerve to the chiasm, where fibres from the nasal retina cross over to opposite side
Optic tract from chiasm to the lateral geniculate nucleus, synapse
Optic radiation from the LGN to the occipital cortex
What is Bitemporal Hemianopia, and what causes it?
Bitemporal Hemianopia = where vision is missing in the outer half of both the right and left visual field
Pressure on chiasm (pituitary tumour) causes bi-temporal hemianopia
What are the two broad categories of visual loss causes?
- Physiological
2. Pathological
Give some examples of physiological causes of visual loss.
Uncorrected Refractive Error.
Myopia, hypermetropia, presbyopia, glasses, contact lenses, refractive surgery.
What are the two categories of Pathological Visual Loss? Which is more common?
Chronic (more common)
Acute
Name the 5 most common treatable causes of chronic visual loss and briefly give their treatment.
Cataract - Surgery
Glaucoma (POAG) – Drops, laser surgery
Age related Macular Degeneration (ARMD) - Sometimes anti-oxidents, anti-vegf, laser)
Diabetic retinopathy (Good DM control, BP+Lipids, laser, surgery)
Name the preventable causes chronic visual loss
Glaucoma
Diabetic retinopathy
Possible dry ARMD (if early detection)
What are the main causes of Acute Loss of Vision? What are they all accompanied by?
• Acute Angle Closure Glaucoma • Temporal • Corneal ulceration • Endophthalmitis • Acute uveitis (All are accompanied by a PAINFUL loss of vision)
In whom is Glaucoma Common (give stats)?
Elderly, 2% over 40yo, 5% over 80yo
What are the clinical features of Glaucoma?
Optic nerve cupping
Peripheral visual field loss What
Most have elevated ocular pressure
Most patients have open angle glaucoma
Uncommonly they may have acute angle closure glaucoma
Most patients have primary glaucoma (some is secondary to other conditions)
Describe the clinical course of Glaucoma.
Asymptomatic in early stages Progressive + irreversible if not detected + treated at early stage • Silent • Slow (5-10 years) • Progressive • Irreversible
Describe the Pathogenesis of Primary Open Angle Glaucoma
Optic nerve damage caused by:
- Elevated IOP
- Reduced ocular vasculature perfusion pressure
How does elevated intraorbital pressure contribute to the development of POA Glaucoma
Reduced drainage of the aqueous humour through the trabecular meshwork drainage angle
What causes reduced ocular perfusion pressure?
- Low blood pressure, esp diastolic
* Peripheral vasospasm