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Glaucoma

Glaucoma. Chapter 23. Role of Technician in Glaucoma. Case history Performing pretesting Aid in treatment Preoperative & postoperative care. Glaucoma. 76 million worldwide with glaucoma Many more undiagnosed! Elevated intraocular pressure Optic nerve cupping Visual field loss.

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Glaucoma

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  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 can’t happen if there’s 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 • Schwalbe’s 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 cornea=lower 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 • It’s 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. Visual Field Defects • Enlarged blind spot • Nerve fiber bundle defect • Bjerrum’s scotoma • Nasal depression or nasal step • Last place is central vision

  40. 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

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

  42. Treatment • Eye drops • Many types & newer formulations • Side effects

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

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

  45. Eyedrops • Hyperosmotic • Angle closure & surgery • Many side effects

  46. Compliance • 20-40% of patients miss dosages • Don’t feel “sick” so don’t take meds • Cost • Pick meds with fewer doses per day

  47. 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

  48. 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

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