Anterior Chamber Disorders Flashcards
What is the seconding leading cause of blindness in the world?
Glaucoma, after cataracts
Types of Glaucoma
- open-angle
- angle-closure
- acute angle closure
- both angle-closures can be divided into primary and secondary forms-
- uveitis
- trauma
- glucocorticoid therapy
- proiliferative retinopathy (Diabetic & HTN) I
Open-Angle Glaucoma
- what is it?
- how does it progress?
- risk factors
-optic neuropathy that results in progressive and gradual loss of retinal ganglion cell axons.
Progression:
- GRADUAL peripheral visual fields lost first then central vision, leading to blindness.
- many people do not notice that its occurring.
Risk Factors :
- Age (>80 4%)
- race; blacks
- family history
- elevated intraocular pressure
- DM, myopia, HTN
Open Angle Glaucoma
-Symptoms
- asymptomatic
- no loss of visual acuity as long as central vision is preserved
- some pts are unaware of field loss even when it has progressed to central “tunnel vision” of 10-20 degrees.
- *Visual field loss cannot be recovered once it has occured.
-increased IOP up to 40 w/o symptoms, may take 25 years to progress to tunnel vision w/o tx.
Open Angle Glaucoma;
-what you see in fundoscopic exam leading you to diagnosis
- presence of cupping: a cup that is greater than 1/3 of the vertical disc diameter is useful threshold for suspicion of glaucoma.
- nerve damage, poor visual field testing, and elevated intraocular pressures.
What is the optic cup? What does it look like? What is normal?
- is the center of the optic disc
- looks white cup-like area in the center of optic disc
- Normal cup to disc ratio is 1:3
- some variation, pts may have almost no cup and others have rather large cup–this is relative.
Features of the optic disc/cup that may lead you to be suspicious of future glaucoma
- the cup enlargers in a vertical oval pattern
- the rim of the nerve on the temporal side, it will be thin or sloped.
Primary Angle-closure Glaucoma
- what is this?
- aka
- characterized by narrowing or closure of the anterior chamber angle closing the normal drainage pathway of the aqueous humor causing a build up leading to elevated IOP and damage of the optic nerve
- chronic glaucoma
Risk Factors of Primary Angle Closure Glaucoma
- family hx
- age (>40-50)
- female
- hyeropia
- medications: decongestants, antipsychotics, antidepressents (d/t anticholinergic effects)
- Race: Inuit and Asian Populations
Primary Angle Closure Glaucoma:
- signs and symptoms
- diagnosis
- often asymptomatic
- progressive cupping and pallor of optic disc
- progressive loss of vision from slight constriction of peripheral fields leading to complete blindness
Dx:
- optic nerve damage (thinning, cupping, or notching of disc rim) AND presence of abnormalities in visual field in the absence of other causes for a field defect.
- adult onset??
- open, normal appearing anterior chamber angles
- absence of known (secondary) causes of glaucoma
Do all patients with open-angle glaucoma have elevated IOP?
NO!
90% of adults w/ IOP>21mmhg have no optic nerve damage
-even up to 40mmhg they can have no vision loss
IOP Parameters for Referral
> 40mmHg Emergency referral
30-40mmHg Urgent referral w/ in 24hrs
25-29mmHg- evaluation within 1 week
23-24mmHg- repeat measurement to confirm and/or referral for comprehensive eye exam
**Normal IOP = 12-20mmhg
Ways to measure eye pressure
- non-contact air puff
- Tonopen
When to screen for glaucoma, what is included in comprehensive eye exam?
- between ages 40-60 every 3-5years for those w/o risk factors, w/ risk factors its 1-2 years.
- suggest periodic exams for black men and women between ages 20-39
-measuring IOP, evaluating the optic nerve, testing for visual field defects.
Tx of Glaucoma
- medications
- -topical and oral
- laser surgery
- -Argon Laser Trabeculoplasty (ALT), improves drainage of the eye
- -Trabeculectomy
- -Drainage implant tubes
-incisional surgery
Acute Angle Closure Glaucoma
- occurs with?
- predisposing factors?
-occurs with closure of a preexisting narrow anterior chamber angle
Predisposing factors:
- eldery
- hyperopes
- inuits
- asians
Acute Angle Closure Glaucoma
- may be precipitated by what?
- example?
-pupillary dilation
Example:
- sitting in dark theater, times of stress, or pharmacologic mydriasis (PANCE!!!!!!!!)
- anticholinergic or sympathomimetics (nebulized bronchodilators, atropne, anti-depressant, nasal decongestant)
Secondary acute angle-closure may be observed with what?
-anterior uveitis or dislocation of lens
Acute Angle Closure Glaucoma Symptoms & signs
Symptoms
- rapid onset
- severe eye pain and HA
- profound visual loss w/ “halos around lights”
- photo-phobia
- nausea and vomiting
Signs:
- conjunctival redness
- cornea edema or cloudiness
- shallow anterior chamber
- mid-dilated pupil that reacts poorly to light
Is angle closure glaucoma an emergency??
YESSSSSSSS.
Acute Angle Closure Glaucoma : treatment approach
- emergent referral to an ophthalmologist, ensure pt can be seen in less than 1hr. if they cannot be seen in that time frame you need to begin treatment.
How do you treat (meds) Acute Angle Closure Glaucoma ?
Treat with Acetazolamide:
it is a carbonic anhydrase inhibitor that reduces edema by decreasing the secretion of aqueous humor thereby decreasing the pressure in the eye.
-Acetazolamide is a non-bacteriostatic sulfonamide
Also give, 1 drop of the following one minute apart:
- 0.5% timolol
- 1.0% apraclonidine
- 2.0% pilocarine
Surgery:
laser peripheral iridotomy or surgical peripheral iridectomy in both eyes.
Prognosis of Acute Angle Closure Glaucoma
good if treated; severe and permanent vision loss if untreated from 3-5 days
Uveitis
- what is this?
- aka
- cause
- this is intraocular inflammation
- anterior iritis
- in most cases the cause is immunologic but may also be from bacteria.
