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41 Cards in this Set
- Front
- Back
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What percentage of causes of blindness does Glaucoma make up for? |
12.3% Glaucoma is the 3rd leading cause of blindness in the world |
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What is Glaucoma? |
Progressive optic neuropathy that results in characteristic morphometric changes in the optic nerve head, resulting in loss of visual function |
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What is a major risk factor for developing glaucoma? |
Raised intraocular pressure |
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Once nerve fibres have been damaged, what cannot be reversed? |
Loss of visual function
Progressive disease – If not controlled adequately, the condition will progress and can lead to blindness |
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What is Classification 1 for Glaucoma? |
Primary glaucoma– Open angle and closed angle Secondary glaucomas– Result due to underlying medical condition or injury to the eye
Congenital glaucoma |
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What is the Classification 2 for Glaucoma? |
• Open • Closed • Developmental • Secondary |
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What are the 3 theories for Glaucomatous Optic Neuropathy? |
• Mechanical - IOP related - Theraputic • Vascular - Perfusion of optic nerve head - Hypoxia, Iscaemia • Immune - Biomarkers |
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What is Primary Open Angle Glaucoma? |
Glaucoma without evident secondary cause, which follows a chronic time course and occurs in the presence of an open anterior chamber angle |
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What is the prevalence of POAG? |
1.5 - 2% for Caucasians
6-8 % for Afro-Caribbean's
0.6% in Asians |
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In which population is the prevalence of POAG higher? |
Black populations |
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What are the risk factors to POAG? |
• Ocular • Systemic • Racial • Environmental |
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What would be normal IOP durinal fluctuation? |
3 to 6 mmHg |
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What would be abnormal IOP durinal fluctuation? |
More than 10mmHg and should raise suspicion |
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What is the connection between IOP and POAG. |
• Prevalence of POAG increases with increasing IOP • Patients who have IOP lowered show decreased rate of progression of field loss • If 2 eyes with POAG, eye with higher IOP 21mmHg shows greater progression of field loss |
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What did studies show about having high CD ratios or asymmetry? |
• risk for developing field defects • Large discs and discs with large CD ratios found to be more susceptible to field loss |
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What effect does myopia have on Glaucoma? |
Two to threefold increased risk of glaucoma compared with those who are not myopic |
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What effect does age have on Glaucoma? |
• indicate increased prevalence of POAG with increasing age • Persons of age 80 have up to 10% prevalence rates • age 40 have 1 - 2% prevalence rates of glaucoma |
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What effect does genetics have on the prevalence of Glaucoma? |
• Positive family history puts individual at increased risk of developing the disease
• Estimates of between 13-47% of POAG cases are familial |
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What is the connection of having diabetes to developing Glaucoma? |
Relative risk of developing POAG is 2.8x greater if diabetic |
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How is lower diastolic perfusion pressure associated with Glaucoma? |
• Lower diastolic perfusion pressure is associated with a marked, progressive increase in the frequency of glaucoma • Hypothesis – Damage occurring to ONH due to poor optic nerve perfusion |
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How is ocular diastolic perfusion pressure calculated? |
Diastolic blood pressure minus eye pressure. • If blood pressure is 120/80 and the eye pressure is 16, the diastolic perfusion pressure 64 (80 - 16) |
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What have studies suggested about ocular diastolic perfusion pressure and Glaucoma? |
• increased risk of glaucoma damage when the ocular diastolic perfusion pressure is less than 55 mmHg • The optic nerve can be compromised if it does not get enough blood supply and the eye pressure (IOP) remains high |
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What are the strong risk factors associated with Glaucoma? |
• High IOP • Aging • Positive family history of glaucoma in a first degree relative • Race (Afro Caribbean) • Suspicious ONH appearance |
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What are the possible risk factors associated with Glaucoma? |
• High Myopia • Diabetes • Hypertension |
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What are the other factors risk factors associated with Glaucoma? |
• History of steroid use
• Migraine headache and peripheral vasospasm
• Gender: Male |
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What does intraocular pressure refer to? |
• the pressure of aqueous within the anterior chamber, keeping the eye inflated
• Balance between aqueous formation and drainage |
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What % of glaucomas does POAG account for? |
85% |
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What are the triad of tests employed to detect the presence of Glaucoma? |
– Optic nerve head assessment – Visual function assessment – Measurement of IOP |
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What are the 2 theories of Glaucomatous Optic Neuropathy? |
Mechanical • IOP related • Superior and inferior poles of ONH
Vascular • Perfusion of optic nerve head |
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What changes to the disc should you look at when investigating Glaucoma? |
• Neuroretinal rim • CD size and asymmetry – Vertical CD • Pallor • Haemorrhages (splinter) • Peripapillary atrophy (beta>alpha) • Lamina Cribosa changes • Baring, Bayonnetting of blood vessels • RNFL changes |
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What changes does POAG cause to the ONH? |
• loss of nerve axons • Widening and deepening of the optic nerve cup • Progressive enlargement of cup in a glaucomatous patient- IOP not controlled. |
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Visual function can be checked by VF tests. Why is this not conclusive? |
• subjective and prone to artefacts • learning and fatigue • time consuming |
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What is used to assess VF with glaucomatus px? |
• Humphrey Visual Field Analyser (HFA) full threshold strategy • Swedish Interactive Thresholding Algorithm (SITA) |
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What changes would be seen in the VF with POAG? |
central 30º
• Paracentral • Arcuate • Nasal step • Temporal wedge • Overall depression • Double arcutae
• End stage |
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What is the definition of Glaucoma? |
A group of eye diseases that results in progressive optic neuropathy that causes characteristic changes in the optic nerve head and retinal nerve fibre layer. |
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Paracentral defect account for what % of all early defects? |
70% |
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Where is paracentral defects usually seen? |
• Between 10 and 20° from fixation
• More commonly superior
• Respect the horizontal midline |
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What is a arcuate defect? |
• More advanced • Coalition of paracentral defects • Respect the horizontal midline • More commonly superior |
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What is nasal step defect? |
• Difference in sensitivity above and below horizontal midline • Highly specific to glaucoma • More common superiorly |
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What is 'normal tenstion glaucoma'? |
Number of individuals with normal- IOP and glaucomatous optic nerve head/ VFD |
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What is ocular hypertensives? |
Similarly, number of individuals with high- IOP and no evidence of glaucoma |
