Gonioscopy Dr. N.suneel ,MS 1st yearDept of ophthalmology
Introduction• Definition:• Why gonioscopy is underutilized?• How frequently we should do gonioscopy?• Indications:• Contraindications:
ANATOMY OF ANGLE OF ANTERIOR CHAMBER• Structures from posterior to anterior anterior surface of iris ciliary band scleral spur trabecular meshwork schwalbe’s line posterior surface of cornea
principle• Critical angle .• Total internal reflection .• Eliminates corneal-air interface• Direct and indirect gonioscopy
Direct gonioscopy Koeppe lens Barkan lens • Prototype diagnostic • Prototype surgical lens lens Richard son - shaffer Thorpe lens • Small koeppe lens • Surgical and diagnostic lens • For use in children • For operating room Layden Swan – jacob lens • For premature infants . • Surgical goniolens for use inWorst gonio lens children.
Indirect gonioscopy Goldmann Goldmann Modifiedsingle mirror three mirror goldmann Mirror :62 1 for angle No viscous bridge, Antereflection 2 for fundus coating for laser trab
Zeiss type Zeiss four mirror • Mirror:64 • Require unger/holder Posner four mirror • Modified zeiss with attached handle Sussman four mirror • Handheld zeiss type gonioprism
Thorpe four mirror• Mirror 62• Require fluid bridgeRitch trabeculoplasty• Four gonioscopy mirrors:59:2 ;62:2• Convex lens over 2Latina trabeculoplasty• One mirror for trabeculoplasty
Direct gonioscopy Technique indirect gonioscopy
Indentation gonioscopy • By changing amount of pressure on cornea one can observe effect on angle width. • Appositional vs PAS . • Platue iris syndrom • Phacomorphic glaucoma
Normal angle landmarks first find the scleralspur for rapid orientation (1) pupil border (2) peripheral iris (3) ciliary body band observe the 6 in order (4) scleral spur (5) trabecular meshwork (6) Schwalbes lineif unable to find , look at another region
Angle width• Estimated by examining the distance between schwalbe’s line and nearest part of iris .• If angle between iris and TM is 20 to 45 deg :wide , <20 deg :narrow• Angle :wide/open/narrow/closed : irregular narrowing : subacute angle closure glaucoma dislocation of lens,cycts, posterior adhesions plus pupillary block Irregular widening :traumatic recession , dislocation of lens,cyclodialysis
Pupil &iris• looking at pupillary border also helpfull for orientation .• Dandruff like flekens at pupillary margin :t/o PXF .• Glaucoma flekens ,post synechiae can be seen in ante surface of lens. contour iris Site of insertion Angulation b/w iris &cornea Neovascularization , hypoplasia , atrophy , polycoria .
Ciliary body band Very light gray -------------------- N in white raceCO Darker gray,traces of brown -- N in dark racesL Darker, slate gray ---------------- melanoma.O Whitish, cobwebby ------------- tear into muscleUR Scleral white cleft behind the S spur---------- cyclodailysisW Narrower --------------hyperopics , PAS ,ID Unusually narrow--- congenital glaucomaT Wider -------------------myopics, tear into CBH cyclodialysis
Scleral spur• Grey white line of varying width,this white colour makes it most helpful landmark for rapid orientation . Spur all visible ------------------------open angle Spur hidden---------------------------uveal meshwork excessively narrow angle closed angle synechias Unusually prominent and white--torn uvealmeshwork, ciliary muscle torn, cyclodialysis
Uveal meshwork• Proper identification avoid confusion with PAS and IP . Homogenous, Network of transperant gray/brown strands ,glittering of variable amount ,unpigmented •IP:long slender isolated strands that stands out away from uveal meshwork •Greater amount nasally .
Trabecular meshwork• Normal variable :covered by uveal meshwork blood in schlemn canal• Charecteristic : filteration area finely granular translucent with or without pigment.• Abnormalities: execessive pigmentation inflammatory exudates blood vessels synechias loss of normal textures traumatic ruptureCongenital abnormalities : posterior embryotoxon (reiger) iridocorneal malformations
Schwalbe’line• Translucent white ledge that projects slightly in AC• Corneal parallelepiped of tha slitlamp beam comes together at this point .• Sampaolesi ‘s line and posterior embryotoxon
Vessels in angle Radial vessels in iris Normal Sea serpent type circumferrential vessel on CB Short and strait vessels seen on CB Erratic course,branch and arborised onAbnormal vessels to angle wall ,stands out as solid cords , may pull the iris to TM Congenitally Congenital glaucoma,axenfield’s syndrom abnormal vessels
IRIS PROCESSES PAS• Thread like fibers of uveal • Adherence of iris to angle tissue structures• Thin Network of strands, • Solid and broad porus• Structures behind seen • Structures behind unseen• Height : usually SS • Height : varies• Peripheral iris tissue wrap • Peripheral iris tissue butts around angle recess flat against TM• Blood vessel -ve • Blood vessel +/_• Pigmentation - /+ ve • Pigmentation +
•Should be differentiated from uveal meshwork •More on inferiorly and nasally. •Dens band whole circumference:EXF PDS,Pigmentation in angle pig.glaucoma •Scattered ,lower parts:previous SX,inflammation, hyphema •Black fine ,coarse balls:old blood Fresh blood :bright red , Blood in angle old blood : black particals and balls Organised clot :synechial filling of angle •Particles ,inflammatory exudates and foreign bodies
Recording gonio findings• Simple discriptive words are more helpful than using numericals .• Three features :post most structure pigmentation iris pattern• Any abnormalities should be noted
Grading of chamber angleScheie grading shaffer system spaeth system• Scheie system: most posterior structure visible.• Shaffer’s system : assess geometric angle width in 4 grades . angle potential for occlusion.• Spaeth system : three dimentional structure of angle - -level of iris insertion and peripheral iris configuration.
Shaffer’ s system• records the angle in degrees of arc subtended by the inner surface of the trabecular meshwork and the anterior surface of iris, about one-third of the distance from its periphery.• assigns a numerical grade to each angle with associated anatomical description, the angle width in degrees and implied clinical interpretation. 20 10 25-35 35-45
Grading of Angle widthShaffer’s systemAngle grade Degrees Numeric grade Clinical Interpetationwide open 30 -45 3-4 closure impossibleNarrow angle 20 2 closure possible(moderate)Narrow angle 10 1 closure possible(extreme) eventually slit angle <10 s portions appearclosedClosed angle 0 closure present
Spaeth classification• A complex grading system that captures detailed three dimensional information in coded form .• High correlation with UBM and biometric gonioscopy.• Interobserver variability - minimal .• Addresses : 1.site of iris insertion . 2.angle width. 3.config of peripheral iris. 4.trabecular meshwork pigmentation. 5.presence/absence of abnormalities.• Grading is made at four cardinal points of angle .
Difficulties and artifacts• Koeppe lens --- narrow the angle• Zeiss lens ----- widen the angle by indentation• Ideal pressure of gonioscopy.• Dimlight provacaton test:• Coreal edema : lower IOP , oral/topicalhyperosmotics epithelial debridment• Cornea guttata : pebbled ,shagreen appearance against white sclera,, easier with gonio than slitlamp
miscellaneous• Biometric gonioscopy• Retroillumination:• Alternatives for angle assessment : UBM Scheimpflug imaging ophthalmic endoscopy.• Immobile pt: four mirror + direct ophthalmoscope .
History of gonioscopy• first person to examine the angle- Trantas .• Contact lens on cornea –saltzman• Later modified by koeppe• Congestive glaucoma was due to closer of angle: Otto Barkan (1936)• Simplified view of angle:goldmann (1938)
summary• Essential tool in management of glaucoma.• Routein gonioscopy can prevent cosiderable number of glaucoma associated blindness.• Advent of handy goniolens• know normal, variations in normal to find abnormals in angle easily.