GLAUCOMA.ppt
- 1. INVESTIGATION OF GLAUCOMA PANKAJ KUMAR VERMA B-Optom – 3rd yr.
- 2. WHAT IS GLAUCOMA ? • A chronic,progressive optic neuropathy caused by a group of ocular condition (increased I.O.P.)which lead to damage of Optic Nerve with loss of Visual function
- 3. PATHOGENESIS • Increase in IOP occurs due to decease in aq. outflow facility • Due to increased resistance to aq. outflow caused by thickening & sclerosis of the trabeculae • Due to synechial angle closure or mechanical occlusion of the angle
- 4. TYPES OF GLAUCOMA • Primary adult Glaucoma- 1) POAG 2) PACG • Secondary Glaucoma • Congenital / Developmental Glaucoma
- 5. WHY INVESTIGATIONS ARE IMPORTANT?? • Diagnosis of Glaucoma • Stage of Glaucoma • Treatment modality • Risk of future Glaucoma
- 6. GLAUCOMA INVESTIGATIONS • Intra Ocular Pressure ( I.O.P.) • Gonioscopy • Fundus Examination • Visual Fields
- 8. Instrumentation • Applanation Tonometer – 1) Goldmann Tonometer 2) Perkins Tonometer • Schiotz tonometer • Tono-Pen • Noncontact Tonometer
- 9. Applanation Tonometer • Based on Imbert Flick Law- For an ideal dry thin walled sphere, the pressure inside the sphere (P) equal to the force necessary to flattened its surface (F) divided by the area of flattening (A) P= F/A
- 11. PROCEDURE • Topical anesthesia • Flurosine staining • Goldmann prism is applied axially to the corneal surface • A pattern of semicircle is seen • Align the inner margins of the semicircle • Reading on the dial *10 equals to IOP
- 12. POTENTIAL ERROR • Inappropriate fluorosine pattern • Pressure on globe • Incorrect calibration • Corneal pathology like corneal oedema. distortion & abnormal thickness
- 13. APPLANATION TONOMETER • Displaces little aqueous • Relatively inexpensive to buy and operate • Compact • Hand held models available • No electronics, reliable with little maintenance • Rarely needs calibrated • Requires topical anesthetic • Poor results with edematous cornea • Influenced by external pressure • corneal abrasions possible
- 15. SCHIOTZ TONOMETER • It measures the depth of indentation of the anaesthetized cornea ,produced by a weighted stylet & is measured by a lever which travels over a scale
- 17. TONO-PEN
- 19. IN RELATION TO GLAUCOMA • IOP permanently raised > 21 mm of Hg – Glaucoma Diagnostic • IOP = 20-21 mm of Hg – Glaucoma suspect • Diurnal variation > 5 mm of Hg – Glaucoma suspect > 8 mm of Hg – Glaucoma Diagnostic
- 20. PROVOCATIVE TEST • Done in Patients having Glaucoma suspect • Water Drinking Provocative Test • Prone Dark Room Test • Mydriatic (Phenylephrine/Tropicamide) Test
- 23. Optic Nerve Head 1)Posterior scleral foramen - • Small cannal – small optic disc(Hyperope) • Large cannal – large optic disc ( Myope) 2)Lamina Cribrosa – • Series of plates of colagenous connective tissue having 200-400 pores containing bundle of retinal nerve fibers
- 24. Cont… • Slight damage – Small pores • Moderate damage – Oval pores • Severe damage – Slit like pores 3) Optic Cup – • Pale depression in the center of the Optic Nerve Head which is not occupied by neural tissue • Small disc – Small cup • Large disc – Large cup
- 25. Normal Optic Nerve Head 1) Cup Disc ratio ( C:D ) = 0.3 :1 2) Neuroretinal Rim – • Tissue between outer edge of the cup & the disk margin • Normal rim has an Orange or pink color • Width of rim I>S>N>T 3) Normal blood vessels
- 26. OPTIC NERVE HEAD
- 27. INSTRUMENTATION • Direct Ophthalmoscope • Indirect Ophthalmoscope • +78 D or +90 D lens with S/L
- 29. +78 or +90D lenses with S/L
- 30. Glaucomatous Damage 1) Retinal Nerve Fiber Damage – • Leads to change in Optic Disc,Visual field 2) Optic Disc Damage – • Increased C:D ratio • Thinning of Neuroretinal rim 3) Vascular Changes – Hemorrhages Tortuosity of Retinal vessels Nasal shifting of Retinal vessels
- 31. Nerve fiber damage • RNF defect may be diffuse or localized • Early localized damage is characterized by slit or wedge shaped defects in RNF • Defect increases as the Glaucomatous changes progresses • At End stage – Total atrophy of NFL
- 32. Optic Disc Damage • Differentiation from Physiological cupping is important • Asymmetry of cups >0.2 • Large cup > 0.6 • Assessment of thickness, symmetry & color of NRR is important
- 33. Early Glaucomatous changes • Vertically Oval Cup • Asymmetry of the Cups > 0.2 • Large Cup > 0.6 • Splinter haemorrhages on or near Optic disc margin • Pallor areas on the Disc • Atrophy of retinal nerve fibre
- 34. Advanced Glaucomatous Changes • Marked Cupping >0.7 • Thinning of neural rim • Bayonetting sign • Pulsation of retinal arterioles may be seen in very high IOP • Lamellar dot sign
- 35. Glaucomatous Optic Atrophy • All neural tissue of the disk is destroyed • Optic nerve head appears white & deeply excavated
- 36. Progression of Disc changes
- 37. Imaging techniques • Heidelberg Retinal Tomography ( HRT) • Optical Coherence Tomography (OCT) • Scanning Laser Polarimetry ( Nerve Fibre Analyzer)
- 41. References • Clinical ophthalmology – Jack J. kanski • Parsons Diseases of the Eye – Ramanjit sihota – Radhika tandon • Optometric instrumentation – David Hansen • Shield’s Text Book of Glaucoma - R . Rand Allingham • Text Book of Glaucoma - Dr. M.R. Jain • Google .com