D - Open Angle Glaucoma 1 & 2 - Week 3 Flashcards
Define Glaucoma (in specific terms. What is lost?)
A disease of the optic nerve with progressive loss of RGC and RNFL with typical functional loss (arcuate VF loss) and no other cause
can occur with or without high iop
OAG is often a presumptive diagnosis based on which 4 factors?
Risk factors
Appearance of RNFL
Appearance of NRR
Typical VF loss
What 4 assessments are needed to determine the level of risk of glaucoma? (i.e. the assessments that will define management)
IOP
Ant. chamber + angle
Fundus: RNFL and NRR
Visual Field
What should a patient present with for us to classify them as a glaucoma patient?
Concomitant presence of RNFL, ON, VF loss
List 5 high risk factors for glaucoma
myopia
RVO
eye injury
iris degeneration
papilledema
List 4 low risk factors for glaucoma
female
diabetes
migraine
sleep apnea
Is IOP a risk factor for glaucoma? Explain
OAG can be IOP independent below 18mmHg (=LTG). However, high IOP is a risk factor for one form of OAG (high pressure OAG)
What assessment do you need to specifically diagnose low tension glaucoma? Why? How can you perform this assessment?
Need the diurnal curve of IOP in all LTG cases to dismiss IOP spikes.
Get patient to come in on multiple days at multiple times to measure IOP.
Alternatively, the ICare tonometer allows the patient to self monitor their IOP (get them to check at 9am, noon, 6pm)
What is considered a higher risk for glaucoma when measuring diurnal IOP?
Any isolated reading >21 or a spike >4mmHg = Higher risk
By how much will corneal thicknes (CCT) modify IOP readings?
Increase in 1mmHg for every 25 micron increase in corneal thickness and vice-versa
What MUST you do if you find an IOP reading >29mmHg? (2)
Evaluate angle for closure and measure CCT
What should you consider if you find an IOP reading <6mmHg?
Consider hypotony or very low CCT/abnormality.
NB: Hypotony = break in cornea with fluid leaking out (an eye can’t survive too long in this condition)
Is a thicker or thinner cornea a higher risk for OAG?
Thin cornea
List 8 risk factors for OAG
Family hx
African-american
DM, migraine, sleep apnea
High BP: aggressive BP lowering
Steroid use
Eye or iris injury/surgery
Myopia
RVO, past papilledema
List 7 risk factors for LTG
Family hx
Japanese
DM, migraine, sleep apnea
Aggressive BP medication
Age >65yo
High myopia
Cardio-vascular disease
What is the purpose of anterior chamber assessment in glaucoma detection? (3)
Assess the angle
Assess to exclude 2ndary OAG (e.g. PXG, PDG, AAU)
Ensure OAG Dx
What is angle closure determined by? (2)
AC depth (shadow test)
TM patent: angle open if VH >0.25.
Need both (and gonio) to diagnose PAC (primary angle closure)
What findings in gonioscopy are necessary for diagnosing PAC? (2)
Angle open to only ATM over >180deg
Angle unimpeded (no pigment, blood or other, congenital malformation)
What disc features should be evaluated for glaucoma? (3)
papillary crescents
NRR thickness
Other signs - haemorrhage
What does a disc cup shape represent?
large disc + surface defect = steep profile for edge