03/04/2015. LOC Talk Anterior Chamber & Gonioscopy 1st April Methods of Assessing Anterior Chamber Depth (and angle width) Outline

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1 LOC Talk Anterior & 1st April 2015 Mr. Areeb Moosavi MBBS BSc FRCOphth Glaucoma Consultant Milton Keynes University Hospital NHS Foundation Trust Methods of Assessing Anterior Open Versus Closed angle Anterior Depth Normal depth 3.5 to 2.5mm <2.5 mm risk for angle closure Shallows by 0.01 mm /year Medical Retina Firm, June 2008 POAG GLAUCOMA JOAG 1 0 Developmental PDS 2 0 (PXF) Episcleral Venous Pressure CCF Sturge-Weber SVC Obstruction OPEN ANGLE Angle Recession Hyphaema Phacoantigenic Ghost Cell Trabecular Obstruction Trabeculitis Fuch s Uveitis Possner Schlossman Drugs Steroids CLOSED ANGLE Epithelial TRAUMA Ingrowth Aphakia SURGERY TUMOURS Angle Closure with pupil block (360 0 PS) INFLAMMATORY Angle Closure w/out pupil block Infection (PAS) DM (CRVO) NVG (Chronic RD) 1 0 PACG Plateau iris Hypermetropia Nanophthalmos 2 0 NF-1 ICD Axenfeld-Reiger Peter s Aniridia ICE Progressive Iris Atrphy Iris Naevus Cogan Reese Methods of Assessing Anterior 1

2 Methods of assessing AC depth 1. Pen Light Method Smith s method for AC depth estimate Smith s method for AC depth estimate Medium illumination Medium magnification (10-16x) Moderate width slit (1-2mm) Offset illumination to 60 degrees from microscope observation system Horizontal beam focussed on central cornea Adjust slit height until corneal and limbus images just appear to meet Multiply slit height by 1.4 Dabasia et al, Optometry in Practice 2013 Volume 14 Issue Van Herick technique Relatively easy to do Narrow slit Offset illumination to 60 degrees from microscope observation system High illumination Medium magnification (10-16x) Temporal and nasal limbus depth assessment Graded according to ratio of peripheral gap between iris and cornea to width of cornea 2

3 Limitations Need a slit lamp Not Linear Grade 3-4 covers 50% Grade 1-2 covers 25% Can only assess nasal and temporal limbus Depends on peripheral corneal integrity Grade 1 cut off; 56-86% sensitivity % specificity Grade 2 cut off; 64-99% sensitivity 58-96% specificity Reliability Grade 1 cut off; 56-86% sensitivity % specificity Grade 2 cut off; 64-99% sensitivity 58-96% specificity Dabasia et al, Optometry in Practice 2013 Volume 14 Issue Decimalised version of van Herick grading Dabasia et al, Optometry in Practice 2013 Volume 14 Issue Split Limbal Technique So how do I assess suspiciously narrow angles.. 3

4 Methods of Assessing Anterior technique Dark room Minimal illumination (1mm width beam) Topical anaesthetic Visco coupling for goldman type lenses Patient reassurance Patient encouragement to keep face forwards Patient looking straight ahead Indentation using Zeiss type lens Patient looking in direction of mirror Indentation 4

5 Methods of Assessing Anterior Anterior chamber Imaging Pentacam Non contact Rotating Scheimflug camera Short wavelength (475nm) blue light 25 slit images in 2 secs Eye movements corrected by a second camera Unable to visualise the most peripheral iris and scleral spur Only visualise angle recess 5

6 Anterior chamber Imaging Ultrasound Biomicroscopy (UBM) Ultrasound based pizoelectric probe Tissue penetration of 5mm Requires acoustic contact (eg water baths, scleral shells, bubble tips) Variation with room illumination, probe position, direction of gaze Anterior chamber image and biometry as obtained using Scheimpflug images from the Oculus Pentacam UBM Images Anterior chamber Imaging Optical Coherence Tomography (AS-OCT) scanning Non contact Near Infra Red light (1310nm) 26,000 A scans per sec Detailed cross sectional images Affected by accommodation, room illumination, direction of gaze More rapid than UBM Technically easier Poor visualisation of the Ciliary Body and suprachoroidal space AS-OCT Imaging 6

7 Methods of Assessing Anterior Treatment options for occludable angles Laser Treatment Yag Laser Iridotomy For closed / narrow drainage angles Usually bilateral OPD procedure So what if things are still scarily narrow..? Angle tends to narrow again after approx. 18 months IOVS j May 2013 j Vol. 54 j No. 5 j 3167 Lens Extraction (cataract) Surgery Other Laser Treatments Known to lower IOP Effect can last 3 years or more Clear lens extraction for angle closure Risk of angle closure effectively eliminated Awaiting Eagle Trial Results Good first procedure before Trabeculectomy or Tube surgery ALT Argon Laser Trabeculoplasty SLT Selective laser Trabeculoplasty 7

8 Cyclodiode Laser Ciliary Body Photocoagulation SLT Yag Laser 50 shots to 180 degrees Selectively targets pigmented trabecular cells monocytes & macrophages Increased Phagocytosis Better in virgin eyes? await results from LIGHT trial Results not convincing in advanced glaucoma ALT Argon Laser Smaller spot size Thermal burn MIGS (Minimally Invasive Glaucoma Surgery) Methods of Assessing Anterior Case Scenario A Case Scenarios 42 year old male Laser iridotomies for narrow angles 2 years ago Now van Herick Grade 2 Any Other information required? Refer in to HES now? Refer in to HES later? 8

9 Case Scenario B Case Scenario C 78 year old female Laser iridotomies for narrow angles 15 years ago IOP RE 14 ; LE 16 Now van Herick Grade 2 No symptoms Any other information required? Refer back to HES? 52 year old female Laser iridotomies for narrow angles 2 years ago Bilateral pseudophakia IOP RE 15 ; LE 17 c/o occasional headaches Any other information required? Refer back to HES? Referral Discussion Refer Van Herrick grade 1 Van Herrick grade 2 if never had gonioscopy or PI Reducing van Herrick grade especially if dense cataract or no previous PI (especially >70 yrs or family history) Symptoms of angle closure; haloes, aching, intermittent redness/blurring in dark Why we like drop-free treatments..videos of the real world! No need to refer Pseudophakics - less angle closure risk than normals van Herrick >2 Debate; Post PI with van Herick 2..? Community follow up with occasional gonioscopy? Thank You Any Questions 9