Glaucoma

1
Glaucoma

• Chapter 23

2
Role of Technician in Glaucoma

• Case history
• Performing pretesting
• Aid in treatment
• Preoperative postoperative care

3
Glaucoma

• 76 million worldwide with glaucoma
• Many more undiagnosed!
• Elevated intraocular pressure
• Optic nerve cupping
• Visual field loss

4
Primary angle-closure glaucoma

• 10 of all glc patients
• 5-10 of elderly population
• More common in women because of shallower AC
• Normal except anatomically have shallow angle

5
Primary angle-closure glaucoma

• Which of the following would have a more shallow
  angle because of typical eye anatomy associated
  with this condition?
• Myopia
• Hyperopia
• Astigmatism

6
Primary angle closure glaucoma

• Crowding in the angle
• Increases 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

7
How does it happen?

• Would dilation or constriction of the pupil cause
  more crowding in the angle?
• What process cant happen if theres a bunch of
  iris tissue crowded into the angle?

8
How does it happen?

• Dilation causes the iris to bunch up in the
  angle
• Aqueous humor cannot drain
• Pressure builds up

9
How does it happen

• Usually begins in conditions that dilate the
  pupils
• Can even happen because of dilation during an eye
  examination!
• Medications could cause it
• Can become fully developed in 30-60min

10
Pain

• This can be very painful
• Patient may be nauseous and vomit
• Cornea clouds up patient cannot see

11
Clinical Manifestations

• Eyelid, conjunctiva, corneal edema
• Cornea appears hazy opaque
• IOP is HIGH
• Can be 50-60mm Hg or higher
• Most people have had warning signs, but may not
  have understood them
• Ache, blur, haloes, rainbows
• Haloes usually inner blue-violet outer
  yellow-red ring

12
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

13
Gonioscopy

• Can differentiate between open-angle and
  narrow-angle glc
• Types
• Goniolens
• Two to four-mirror lenses

14
Gonioscopy
15
What we see through a gonio lens

• Ciliary body band
• grayish
• Scleral spur
• White line
• Trabecular meshwork
• Pigmented
• Schwalbes line

16
Gonio view
17
Treatment

• Laser iridotomy
• Do it bilaterally
• 50-70 will have attack in other eye!
• Allows AC to deepen

18
Treatment

• Must lower pressure first before attempting
  iridotomy

19
POAG

• Chronic, progressive, bilateral
• Usually shows up after age 40, but diagnosed
  earlier now with our better screening methods
• Usually caused by decreased outflow

20
POAG

• Diagnosis usually by results of three conditions
• 1. increased IOP
• 2. optic nerve cupping
• 3. visual field defects

21
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

22
Secondary Glaucoma

• Caused by some other factor
• Lens changes/dislocations
• Scar tissue
• Synechia
• Iritis
• Tumor
• Trauma
• Steroid use chronic high-dose

23
Congenital Glaucoma

• Rare
• Infant may be very light sensitive and tear a lot
• Corneal haziness enlarged (buphthalmos)

24
Tonometry

• Measure of intraocular pressure
• Many different ways

25
Indentation (Schiotz) tonometry

• Not used much anymore
• Third world countries
• Anesthetic
• Rests on cornea indents it
• More indentation softer cornealower IOP

26
Applanation Tonometry

• Cornea flattened
• More accurate
• The standard of measurement

27
Goldmann Applanation Tonometry

• Disadvantage-not portable
• Need significant training to accurately perform
• Anesthetic fluorescein blue light green
  reflection

28
Goldmann Applanation Tonometry
See page 438 for incorrect flourescein bands
29
IOP

• Pressure varies during the day
• Usually highest early am (diurnal variation)

30
Perkins hand-held applanation tonometer

• Same principle as Goldmann
• Its rather bulky

31
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 accurate
• Can use with contact lenses

32
Tonopen

• Portable, hand-held, lightweight
• Applanation technique

33
Optic Disk Evaluation

• Cupping pallor (color-pale)
• Center depression is the cup
• The fibers around the edges are the rim

34
Glaucoma cupping - asymmetric
35
Heidelberg Retina Tomograph

• 3-D topographic map of ONH

36
GDx VCC

• Looks at the nerve fiber layer
• Printout give color-coded picture showing
  thickness of NFL

37
Optical Coherence Tomographer OCT

• Cross section of retina
• Can show macular thickness, retinal NFL thickness
  and view optic nerve
• Compare values over time

38
Visual Field

• Usually VF defects correspond to appearance of
  damage to optic disk

39
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40
Visual Field Defects

• Enlarged blind spot
• Nerve fiber bundle defect
• Bjerrums scotoma
• Nasal depression or nasal step
• Last place is central vision

41
Types of Perimetry

• Kinetic
• Move object from nonseeing area to a seeing area
• Goldmann

• Static
• Uses stationary test objects presented randomly
• Threshold static perimetry
• Change intensity of light
• Humphrey

42
Treatment

• No cure but can be controlled in many cases
• Compliance
• Reduction of IOP is principal goal

43
Treatment

• Eye drops
• Many types newer formulations
• Side effects

44
Eyedrops

• Miotics
• Pilocarpine
• Can interfere with vision
• Sympathomimetics
• Propine
• Beta blockers
• Timoptic (timolol)
• Still used a lot

45
Eyedrops

• Carbonic anhydrase inhibitors
• Oral closed angle
• Drops now available
• Prostaglandins
• Lumigan, xalatan
• Alpha agonists
• alphagan

46
Eyedrops

• Hyperosmotic
• Angle closure surgery
• Many side effects

47
Compliance

• 20-40 of patients miss dosages
• Dont feel sick so dont take meds
• Cost
• Pick meds with fewer doses per day

48
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

49
Surgery

• Create an opening between anterior chamber and
  subconjunctival space
• With or without implant (tube shunt)
• Post-op care is critical
• Hypotony, wound leak, fluid shifts, infection