Glaucoma Ch23
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Transcript of Glaucoma Ch23
![Page 1: Glaucoma Ch23](https://reader036.fdocuments.in/reader036/viewer/2022070508/577ca6db1a28abea748c1060/html5/thumbnails/1.jpg)
Glaucoma
Chapter 23
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Role of Technician in Glaucoma
Case historyPerforming pretestingAid in treatmentPreoperative & postoperative care
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Glaucoma
76 million worldwide with glaucomaMany more undiagnosed!
Elevated intraocular pressureOptic nerve cuppingVisual field loss
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Primary angle-closure glaucoma
~10% of all glc patients5-10% of elderly populationMore common in women because of
shallower ACNormal except anatomically have shallow
angle
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Primary angle-closure glaucoma
Which of the following would have a more shallow angle because of typical eye anatomy associated with this condition?MyopiaHyperopiaAstigmatism
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Primary angle closure glaucoma
Crowding in the angleIncreases with age
Why? What structure inside the eye physically changes/grows with age?
Less than 20 degrees in width is said to constitute narrow angle glaucoma
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How does it happen?
Would dilation or constriction of the pupil cause more crowding in the angle?
What process can’t happen if there’s a bunch of iris tissue crowded into the angle?
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How does it happen?
Dilation causes the iris to “bunch up” in the angle
Aqueous humor cannot drainPressure builds up
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How does it happen
Usually begins in conditions that dilate the pupilsCan even happen because of dilation during an
eye examination!Medications could cause it
Can become fully developed in 30-60min
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Pain
This can be very painfulPatient may be nauseous and vomitCornea clouds up & patient cannot see
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Clinical Manifestations
Eyelid, conjunctiva, corneal edemaCornea appears hazy & opaque
IOP is HIGHCan be 50-60mm Hg or higher
Most people have had warning signs, but may not have understood themAche, blur, haloes, rainbowsHaloes usually inner blue-violet & outer yellow-
red ring
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Diagnosis
Narrow angle identified in eye exam
Even though pressure may be normal at exam, definitely have to identify narrow angles!
Gonioscopy – the only true way to properly assess the narrowness of the angle
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Gonioscopy
Can differentiate between open-angle and narrow-angle glc
TypesGoniolensTwo to four-mirror
lenses
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Gonioscopy
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What we see through a gonio lens
Ciliary body bandgrayish
Scleral spurWhite line
Trabecular meshworkPigmented
Schwalbe’s line
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Gonio view
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Treatment
Laser iridotomyDo it bilaterally
50-70% will have attack in other eye!
Allows AC to deepen
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Treatment
Must lower pressure first before attempting iridotomy
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POAG
Chronic, progressive, bilateralUsually shows up after age 40, but
diagnosed earlier now with our better screening methods
Usually caused by decreased outflow
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POAG
Diagnosis usually by results of three conditions1. increased IOP2. optic nerve cupping3. visual field defects
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Ocular Hypertension
Have high IOP but no VF or ONH changes
This means they can tolerate higher than normal IOP without damage
But they are a glaucoma suspect because of this, although most will never need meds to treat this
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Secondary Glaucoma
Caused by some other factorLens changes/dislocationsScar tissueSynechiaIritisTumorTraumaSteroid use – chronic & high-dose
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Congenital Glaucoma
RareInfant may be very light sensitive and tear
a lotCorneal haziness & enlarged
(buphthalmos)
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Tonometry
Measure of intraocular pressureMany different ways
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Indentation (Schiotz) tonometry
Not used much anymore
Third world countriesAnestheticRests on cornea &
indents itMore indentation =
softer cornea=lower IOP
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Applanation Tonometry
Cornea flattenedMore accurateThe standard of measurement
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Goldmann Applanation Tonometry
Disadvantage-not portable
Need significant training to accurately perform
Anesthetic + fluorescein + blue light = green reflection
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Goldmann Applanation Tonometry
See page 438 for incorrect flourescein bands
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IOP
Pressure varies during the dayUsually highest early am (diurnal
variation)
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Perkins hand-held applanation tonometerSame principle as
GoldmannIt’s rather bulky
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Non-contact Tonometer“Airpuff”Principle of how long it
takes the puff of air to exactly flatten cornea
Takes less time to flatten a soft eye (lower IOP)
Not as accurateCan use with contact
lenses
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Tonopen
Portable, hand-held, lightweight
Applanation technique
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Optic Disk Evaluation
Cupping + pallor (color-pale)
Center depression is the cup
The fibers around the edges are the rim
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Glaucoma cupping - asymmetric
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Heidelberg Retina Tomograph
3-D topographic map of ONH
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GDx VCC
Looks at the nerve fiber layer
Printout give color-coded picture showing thickness of NFL
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Optical Coherence Tomographer OCTCross section of
retinaCan show macular
thickness, retinal NFL thickness and view optic nerve
Compare values over time
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Visual Field
Usually VF defects correspond to appearance of damage to optic disk
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Visual Field Defects
Enlarged blind spotNerve fiber bundle defectBjerrum’s scotomaNasal depression or nasal step
Last place is central vision
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Types of Perimetry
KineticMove object from
nonseeing area to a seeing area
Goldmann
Static Uses stationary test
objects presented randomly
Threshold static perimetryChange intensity of
lightHumphrey
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Treatment
No cure but can be controlled in many casesCompliance
Reduction of IOP is principal goal
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Treatment
Eye dropsMany types & newer formulationsSide effects
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Eyedrops
MioticsPilocarpineCan interfere with vision
SympathomimeticsPropine
Beta blockersTimoptic (timolol)Still used a lot
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Eyedrops
Carbonic anhydrase inhibitorsOral – closed angleDrops now available
ProstaglandinsLumigan, xalatan
Alpha agonistsalphagan
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Eyedrops
HyperosmoticAngle closure & surgeryMany side effects
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Compliance
20-40% of patients miss dosagesDon’t feel “sick” so don’t take medsCostPick meds with fewer doses per day
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Other treatments
Argon laser trabeculoplasty (ALT)Laser holes into trabecular meshwork
Selective laser trabeculoplasty (SLT)Less thermal than ALT so less scarring
Excimer laser trabeculostomy (ELT)Least damage Waiting FDA approval
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Surgery
Create an opening between anterior chamber and subconjunctival space
With or without implant (tube shunt)Post-op care is criticalHypotony, wound leak, fluid shifts,
infection