Glaucoma Flashcards
What is glaucoma?
increased IOP damages optic nerve (cupping/optic atrophy) causing vision loss
Percentage of ppl with glaucoma who become blind?
4%
What is the greatest systemic risk factor for glaucoma?
Age; >60 most common
Risk factors for glaucoma?
- age
- race (AA)
- Hx of IOP, high myopia, CVD, HTN, low BP, CAD, DM
- family Hx
What causes glaucoma?
accelerated and exaggerated normal aging changes in anterior chamber of eye; affects schlemm’s canal and uveoscleral outflow pathway (anterior canal to angle)
Optic nerve head effects of glaucoma?
- swollen cup - closer to 4:1 c/d
- thinning of disc rim (superior and inferior notching)
- prog. loss of neural rim tissue
- disc hemorrhages
- loss of nerve fibers
visual field changes in glaucoma?
- nasal field loss
- paracentral field loss
- mid peripheral field lossAQ
5 Types of glaucoma?
- primary open-angle (POAG)
- angle-closure
- congenital
- childhood
- secondary
POAG characteristics?
- most common (90%)
- bilateral (not always symmetric)
- optic nerve damage
- visual field deficit
- adult onset
- normal appearing anterior chamber angles
- overproduction problem or outflow thru canal/meshwork problem
- absence of secondary cause
Progression of POAG and congenital glaucoma?
- asymptomatic in early stages
- can result in blindness (total optic nerve atrophy)
5 Causes of secondary glaucoma?
- trauma
- uveitis (inflammation of pigmented layer behind retina in front of sclera)
- chronic steroid use (COPD)
- DR
- ocular vascular occlusion
characteristics of neovascular glaucoma?
iris and anterior chamber angle neovascularized (bloody iris)
Is POAG more common in males or females?
females
AA risk factors for POAG?
- blindness (4x)
- age: 10% prevalence @ >70
- earlier onset
- more advanced upon discovery
- elevated IOP
How to screen for POAG?
- IOP measurements
- optic disc evaluation
- visual field testing
- OCT (optical coherence tomography)
- HRT (Heidelberg retinal tomography)
- Pacymetery
What is OCT (optical coherence tomography)?
imaging test: uses light wave to take cross-section pictures of retina; allows you to visualize layers of the retina (and how thick they are)
what is the most effective screening too for glaucoma?
periodic comprehensive eye examinations
what is pachymetry?
measurement of corneal thickness (in microns)
normally done with U/S
average CT= 545 microns
How can corneal thickness effect the IOP measurement?
Can be interpreted as too low or high depending on corneal thickness. 10 microns=1 mm pressure
ex. Eye with 20 mm Hg; 500 micron thick cornea… real pressure = 25 mm Hg
Risk factor analysis: how are the levels of glaucoma risk defined?
high: 4 or more Risk factors
moderate: 3
low: 2 or less
During eye exam your patient presents with normal visual fields, open/normal appearing anterior chamber angles, elevated IOP, and abnormal optic disc; would you suspect a possible case of glaucoma?
yes
Tx for glaucoma?
- halt further visual loss
- halt further optic nerve damage
What do topical glaucoma medications target?
autonomic nervous system
topical medications used for glaucoma?
- Beta blockers (timolol, levobunolol, carteolol, metipranolol, betaxolol)
- adrenergic agonists (epi, propine, apraclonidine, brimonidine)
- cholinergic agonists (carbachol, echothiophate iodine, demecarium bromide)
- oral carbonic anhydrase inhibitors (acetazolimide, methazolamide, brinzolamide, dorzolamid, dorzolomide and timolol)
- prostoglandins (xalatan)
What is the only selective B1 blocker for glaucoma?
betaxolol (betoptic or betoptic-S)
what are the advantages of beta blockers?
- minimal ocular side effects
- systemic side effects well understood
- one per day
- cost
- stabilization of visual fields with betoptic
What are disadvantages of beta blockers?
- exacerbate breathing problems
- can’t use with CHF, bradycardia, heart block
- decreased exercise tolerance
- decreased HDL and increased triglycerides
- CNS effects (depression, anxiety, confusion, hallucinations, drowsiness, weakness, memory loss, impotence)
- decreased effect with systemic beta blockers
Why is betoptic a good choice for pt with COPD?
Decreased breathing problems and increased exercise tolerance problems as opposed to non-selectives.
What beta blocker minimizes decreased HDL and increased triglycerides?
ocupress
how do adrenergic agonists effect glaucoma?
- decrease aqueous production
- increase aqueous drainage
what two alpha-2 agonist medications are used for glaucoma?
apraclonidine
brimonidine
S/E of topical adrenergic agonists?
- increased BP
- tachy-arrythmias
- tremor
- headache
- anxiety
- burning in eye
- conjunctival infection
- pupillary dilation
- allergic rxn
What are the S/E of topical cholinergic agonists?
- increased bronchial secretions
- nausea
- vomitting
- diarrhea
- apnea
- increased myopia
- eye brow pain
- decreased vision
- retinal detachment
How do oral carbonic anhydrase inhibitors fxn?
inhibit carbonic anhydrase, an enzyme needed for aqueous fluid production
What are the advantages of carbonic anhydrase inhibitors?
few systemic side effects
what are the disadvantages of carbonic anhydrase inhibitors?
- less effective than timoptic
- allergy
- stinging
- cost
S/E of oral carbonic anhydrase inhibitors?
- malaise
- anorexia
- depression
- paraesthesias
- serum electrolyte abnormalities
- renal calculi
- aplastic anemia
- corneal edema
how do prostaglandins effect glaucoma?
increase removal of aqueous fluid
advantages of xalantan?
- equal or better IOP lowering (compared to timoptic)
- qD
- minimal side effects
- increased uveoscleral outflow (good for LTG)
what is best for low tension glaucoma’?
xalantan
What are the disadvantages of prostoglandins?
- iris pigmentation
- eyelash thickening
- new medication
- cost
- uveitis
- CME (cystoid macular edema)
why do medical treatments with glaucoma fail?
- noncompliance
- target pressures too low
- fluctuations of IOP
Surgical glaucomal procedures?
- laser surgery (Slt)
- filtering surgery
- cyclodestructive surgery
- drainage device surgery
- trabeculoplasty
- GDD (glaucoma drainage device/baerveldt glaucoma implant)
Angle-closure high risk groups?
- elderly
- eskimos
- asians
- females
- hyperopic patients
- family Hx
Symptoms of acute glaucoma?
- ocular pain
- redness
- mid dilated pupil
- brow pain
- blurred vision
- halos
- headaches
- nausea
- vomiting
- steamy cornea/eye
How to approach suspected acute glaucoma?
- eye exam
- IOP measurement
- initiate medical tx
Tx for acute glaucoma (initial)?
- beta blocker (timoptic) or alpha agonist (alphagan)
- acetazolamide 500 mg PO or IV
- oral glycerine or isosorbide (1cc/kg)
- Mannitol 20% IV 300-500cc
- LT follow-up
how do beta blockers affect glaucoma?
decrease aq. humor production
How should you manage pt at risk for acute angle closure glaucoma?
prophylactiv iridotomy if chamber angle is narrow to create large pathway for removal of fluid;
miotics (drops that stimulate the PSNS and constrict the pupil) are not a substitute
