Gonioscopic Evaluation of the Anterior Chamber Angle
Gonioscopic Evaluation of the Anterior Chamber Angle
Gonioscopic Evaluation of the Anterior Chamber Angle
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<strong>Gonioscopic</strong> <strong>Evaluation</strong> <strong>of</strong> <strong>the</strong><br />
<strong>Anterior</strong> <strong>Chamber</strong> <strong>Angle</strong><br />
University <strong>of</strong> Milan Bicocca<br />
June 2010<br />
Anthony Cavallerano, O.D.<br />
VA Boston Health Care System<br />
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The New England College <strong>of</strong> Optometry<br />
Boston Massachusetts<br />
anthony.cavallerano@va.gov<br />
cavalleranot@neco.edu
GONIOSCOPY<br />
• Gonioscopy is a technique that allows<br />
visualization <strong>of</strong> <strong>the</strong> anterior chamber angle<br />
structures and is used to diagnose abnormalities<br />
<strong>of</strong> <strong>the</strong> anterior segment, in particular <strong>the</strong><br />
anterior chamber angle structures.<br />
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Gonioscopy - Indications<br />
• Glaucoma<br />
– Open angle<br />
– Narrow angle<br />
– Pigmentary/PXF<br />
– Neovascular<br />
• Post Trauma<br />
• Suspiciously marrow angle prior to dilation<br />
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KOEPPE GONIOSCOPY<br />
• Convex lens is placed on anes<strong>the</strong>tized cornea<br />
• Hand held focal illuminator/patient in supine position<br />
• Wide angle view <strong>of</strong> chamber<br />
• Excellent impression <strong>of</strong> iris contour and angle approach<br />
• Low magnification/distorts <strong>the</strong> angle very slightly<br />
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• Koeppe Lens<br />
– Direct Optical system<br />
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Gonioscopy – Koeppe Lens<br />
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INDIRECT GONIOSCOPY<br />
• Zeiss 4 mirror lens<br />
• Goldmann (Universal) mirror lens.<br />
• Slit lamp biomicroscope<br />
• Each quadrant examined indirectly by placing<br />
<strong>the</strong> mirror in <strong>the</strong> quadrant opposite <strong>the</strong> area<br />
to be examined<br />
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• Zeiss 4 mirror lens<br />
– Indirect Optics<br />
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Gonioscopy – Posner lenses<br />
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Gonioscopy – Posner Placement<br />
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Zeiss 4-mirror Zens<br />
• 4 mirrors positioned for gonioscopy<br />
• Central lens for <strong>the</strong> posterior pole<br />
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• Precorneal tear film serves as <strong>the</strong> intervening fluid<br />
• Four angles viewed rapidly<br />
• Central lens provides adequate view <strong>of</strong> posterior<br />
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Indirect Gonioscopy (Contemporary)<br />
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Gonioscopy - Instrumentation<br />
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Gonioscopy – Sussman Lens<br />
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Universal Lens Placement<br />
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<strong>Anterior</strong>-<strong>Chamber</strong> <strong>Angle</strong> Anatomy<br />
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A/C <strong>Angle</strong> and Trabecular Drainage<br />
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Indirect Gonioscopy (Contemporary)<br />
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Gonioscopy - Instrumentation<br />
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Universal/Goldmann Lens<br />
• Most commonly used gonioscopic technique<br />
• Lens eliminates internal reflection redirects image<br />
incorporated in <strong>the</strong> lens<br />
• Requires topical anes<strong>the</strong>tic and intervening fluid<br />
• Monitor corneal epi<strong>the</strong>lium<br />
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Three Mirror Universal (Goldmann) Lens<br />
• Versatile lens<br />
• Larger, easier to handle<br />
• Additional mirrors/lenses<br />
– <strong>Gonioscopic</strong> mirror<br />
– Equatorial and peripheral mirrors<br />
– Central fundus lens for optic disc and macula<br />
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EXAMINATION TECHNIQUES<br />
Goldmann (Univerdsal) lens<br />
• Align slit lamp for patient and examiner<br />
• Low magnification (10x)<br />
• Scan anterior portion <strong>of</strong> eye<br />
• Anes<strong>the</strong>tize cornea<br />
• Fill <strong>the</strong> meniscus <strong>of</strong> <strong>the</strong> lens, halfway with gonioscopic<br />
solution<br />
• Intervening fluid forms strong capillary bonds and allows<br />
moderate lens manipulation<br />
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• Corneal ulcer<br />
Contraindications<br />
• Corneal abrasion<br />
• Blunt or penetrating injury<br />
• New/recent surgical wound<br />
Goldmann tonometry prior to<br />
gonioscopy<br />
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Technique<br />
Insertion<br />
• Set up slit lamp (low mag., narrow beam, straight<br />
ahead)<br />
• Have patient look down, pull upper lid<br />
• Have patient to look up, pull lower lid<br />
• Place lower edge <strong>of</strong> lens in inferior cul-de- sac<br />
• Tilt lens forward against plane <strong>of</strong> cornea, let lower lid<br />
go<br />
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• Position/focus microscope into gonio mirror<br />
• Increase magnification to 16x<br />
• Lens in place - held by capillary action.<br />
– Balance lens without much pressure exerted to globe
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Removal<br />
Technique<br />
• Break suction between lens and cornea<br />
• Irrigate eye with sterile saline<br />
• Clean lens with contact lens cleaning<br />
solution<br />
• Rinse well, air dry and store in container<br />
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STRUCTURAL OVERVIEW TO<br />
UNDERSTANDING GONIOSCOPY<br />
PUPIL AND IRIS:<br />
• pupillary margin<br />
• Iris plane<br />
• Peripheral iris insertion<br />
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Normal angle<br />
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Grading<br />
4 structures = wide open<br />
3 structures<br />
2 questionable<br />
1 = occludable (Schwalbe’s line)<br />
Grading angles<br />
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Normal angle
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CILIARY BODY (CBB)<br />
• Highly vascularized<br />
• <strong>Anterior</strong> iris stroma is continuous over<br />
anterior ciliary body<br />
• Irregular threadlike thickening <strong>of</strong> fibers, called<br />
iris processes branch, coalesce over anterior<br />
ciliary body<br />
• Do not cause increased IOP<br />
• Terminate at scleral spur but occasionally at<br />
Schwalbe's line.<br />
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Scleral Spur<br />
• Easily seen in wide angle at <strong>the</strong> anterior end <strong>of</strong> <strong>the</strong><br />
angle recess where <strong>the</strong> ciliary body inserts.<br />
• Thin white line<br />
• Iris processes stop at this point<br />
• Easily visible when blood fills Schlemm's canal, or<br />
pigment deposited in <strong>the</strong> meshwork.<br />
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SCHLEMM'S CANAL<br />
• Often appears as a gray zone just above scleral spur<br />
• More obvious when blood-filled<br />
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TRABECULAR MESHWORK (TM)<br />
• Trabecular pigment band forms directly in front <strong>of</strong> <strong>the</strong><br />
Schlemm’s canal due to deposition <strong>of</strong> pigment <strong>of</strong> granules<br />
• Denser in pigmentation in brown iris patients than blue eyed<br />
patients<br />
• Band becomes less translucent and more opaque with age<br />
• Inferior angle becomes more pigmented<br />
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SCHWALBE'S LINE<br />
• <strong>Anterior</strong> termination <strong>of</strong> Descemet's membrane<br />
• Represents <strong>the</strong> change in curvature between <strong>the</strong> flat<br />
sclera and steep cornea<br />
• A condensation <strong>of</strong> collagenous fibers which runs<br />
around <strong>the</strong> inner peripheral cornea<br />
• Marks <strong>the</strong> anterior insertion limit <strong>of</strong> <strong>the</strong> angle<br />
structures<br />
• Pigment may be deposited on Schwalbe's line<br />
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SL<br />
TM<br />
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SS<br />
CBB
Abbreviations<br />
• CBB: Ciliary body band<br />
• TM: Trabecular meshwork<br />
• SS: Scleral spur<br />
• SL: Schwalbe’s line<br />
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Recording<br />
• record <strong>the</strong> deepest structure visible in each <strong>of</strong> <strong>the</strong> four<br />
quadrants as shown below (most POSTERIOR structure)<br />
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OD OS
• Recording:<br />
OD OS<br />
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• Classification <strong>of</strong> angle width:
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USE OF GONIOSCOPY<br />
1. Pre -dilation evaluation <strong>of</strong> potentially narrow angles<br />
2. <strong>Evaluation</strong> <strong>of</strong> all potential glaucoma conditions<br />
3. Narrow angle glaucoma<br />
4. Confirmation <strong>of</strong> Primary angle open glaucoma or chronic<br />
open angle glaucoma<br />
5. Secondary open angle glaucoma:<br />
examples:<br />
» Pigmentary dispersion<br />
» Ocular trauma: angle recession<br />
» Lens induced<br />
» Neovascular glaucoma<br />
6. Tumors <strong>of</strong> iris and ciliary body<br />
7. O<strong>the</strong>rs<br />
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Slit Lamp Examination and<br />
• Intact cornea<br />
Tonometry<br />
• <strong>Angle</strong> estimation (temporarily or<br />
nasally)<br />
• Goldmann tonometry<br />
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2. If angle on Van herick are less than 1/4: 1, use <strong>the</strong><br />
gonioscopy lens to evaluate <strong>the</strong> angle.<br />
Van herick:<br />
Width <strong>of</strong> cornea equal to 1<br />
(3/4, 1/2. 1/4, 1/8)<br />
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Width <strong>of</strong> shadow compare to<br />
width <strong>of</strong> cornea in fractions
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3. What is considered a narrow versus open<br />
angle on gonioscopy<br />
OD OS<br />
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Shadow Technique<br />
• Penlight technique: temporally<br />
• If iris is flat, total illumination<br />
• If iris is bowed, shadow forms<br />
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