1 / 17

INTRODUCTION TO GLAUCOMA

INTRODUCTION TO GLAUCOMA. 1. Aqueous outflow. Anatomy. Physiology. 2. Classification of secondary glaucoma. 3. Tonometers. 4. Gonioscopy. 5. Anatomy of retinal nerve fibres. 6. Optic nerve head. 7. Humphrey perimetry. Aqueous outflow. Anatomy. Physiology. a - Uveal meshwork.

diane
Download Presentation

INTRODUCTION TO GLAUCOMA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. INTRODUCTION TO GLAUCOMA 1. Aqueous outflow • Anatomy • Physiology 2. Classification of secondary glaucoma 3. Tonometers 4. Gonioscopy 5. Anatomy of retinal nerve fibres 6. Optic nerve head 7. Humphrey perimetry

  2. Aqueous outflow Anatomy Physiology a - Uveal meshwork a - Conventional outflow b - Corneoscleral meshwork b - Uveoscleral outflow c - Schwalbe line c - Iris outflow d - Schlemm canal e - Collector channels f - Longitudinal muscle of ciliary body g - Scleral spur

  3. Classification of secondary glaucomas Open-angle a b a. Pre-trabecular - membrane over trabeculum b. Trabecular - ‘clogging up’ of trabeculum Angle-closure c d c. With pupil block - seclusio pupillae and iris bombé d. Without pupil block - peripheral anterior synechiae

  4. Tonometers Goldmann Schiotz Perkins Contact applanation Contact indentation Portable contact applanation Pulsair 2000 (Keeler) Tono-Pen Air-puff Portable non-contact applanation portable contact applanation Non-contact indentation

  5. Goniolenses Goldmann Zeiss • Single or triple mirror • Four mirror • Contact surface diameter 12 mm • Contact surface diameter 9 mm • Coupling substance required • Coupling substance not required • Suitable for ALT • Not suitable for ALT • Not suitable for indentation gonioscopy • Suitable for indentation gonioscopy

  6. Indentation gonioscopy Differentiates ‘appositional’ from ‘synechial’ angle closure Press Zeiss lens posteriorly against cornea Aqueous is forced into periphery of anterior chamber

  7. Indentation gonioscopy in iridocorneal contact During indentation Before indentation • Part of angle is forced open • Complete angle closure • Apex of corneal wedge not visible • Part of angle remains closed by PAS

  8. Angle structures Schwalbe line Trabeculum Schlemm canal Scleral spur Iris processes

  9. Shaffer grading of angle width Grade 4 (35-45 ) • Ciliary body easily visible Grade 3 (25-35 ) • At least scleral spur visible Grade 2 (20 ) 2 3 1 • Only trabeculum visible 4 0 • Angle closure possible but unlikely Grade 1 (10 ) • Only Schwalbe line and perhaps • top of trabeculum visible • High risk of angle closure Grade 0 (0 ) • Iridocorneal contact present • Apex of corneal wedge not visible • Use indentation gonioscopy

  10. Anatomy of retinal nerve fibres Papillomacular bundle Horizontal raphe

  11. Optic nerve head Small physiological cup a - Nerve fibre layer a b b - Prelaminar layer c - Laminar layer c Large physiological cup • Normal vertical cup-disc ratio is 0.3 or less • 2% of population have cup-disc ratio > 0.7 • Asymmetry of 0.2 or more is suspicious Total glaucomatous cupping

  12. Types of physiological excavation Cup with sloping temporal wall Larger and deeper punched-out central cup Small dimple central cup

  13. Pallor and cupping Pallor - maximal area of colour contrast Cupping - bending of small blood vessels crossing disc Cupping and pallor correspond Cupping is greater than pallor

  14. Humphrey perimetry

  15. Reliability Indices 1. Fixation losses • Detected by presenting stimuli in blind spot 2. False positives • Stimulus accompanied by a sound • High score suggests a ‘trigger happy’ patient 3. False negatives • Failure to respond to a stimulus 9 dB brighter than previously seen at • same location • High score indicates inattention, or advanced field loss

  16. Deviations 1. Total • Upper numerical display shows difference (dB) between • patient’s results and age-matched normals • Lower graphic display shows these differences as grey scale 2. Pattern • Similar to total deviation • Adjusted for any generalized depression in overall field

  17. Global Indices 1. Mean deviation (elevation or depression) • Deviation of patient’s overall field from normal • p values are < 5%, < 2%, < 1% and < 0.5% • The lower the p value the greater the significance 2. Pattern standard deviation • Departure of visual field from age-matched normals 3. Short-term fluctuation • Consistency of responses • 2 dB or less indicates reliable field • > 3 dB indicates either unreliable or damaged field 4. Corrected pattern standard deviation • Departure of overall shape of patient’s hill of vision from • age-matched normals

More Related