GONIOSCOPIC ANATOMY

• GONIOSCOPIC ANATOMY INCLUDES STRUCTURES IN ANTERIOR CHAMBER WHICH CAN BE VISUALISED BY GONIOSCOPIC EXAMINATION AS THEY ARE INVOLVED IN A NUMBER OF LASER AND INCISIONAL GLAUCOMA PROCEDURES

ANGLE OF ANTERIOR CHAMBER

• IT IS THE SITE OF PRIMARY PATHOLOGICAL CHANGES RESPONSIBLE FOR INCREASED IOP ASSOCIATED WITH ALMOST ALL GLAUCOMAS,BUT ALSO FOCUS OF MOST OF MEDICAL AND SURGICAL PROCEDURES DESIGNED TO ALLEVIATE INCREASED IOP.

• DEPTH AND ANGLE WIDTH ARE TWO DIFFERENT MEASUREMENTS OF ANGLE OF ANTERIOR CHAMBER

• AS SIZE AND SHAPE OF EYEBALL IS GENETICALLY DETERMINED,THERE WILL BE IMPORTANT GONIOSCOPIC STRUCTURAL DIFFERENCES AMONG DIFFERENT RACIAL GROUPS.

• MORE ANTERIORLY INSERTING IRIS ROOT AND POTENTIALLY OCCLUDABLE ANGLE IS SEEN IN ASIAN POPULATION,WHERE AS HIGHER INCIDENCE OF PRIMARY AND CHRONIC ANGLE CLOSURE GLAUCOMA IS GENERALLY COMMON IN CHINESE AND JAPANESE.

• DEEP CHAMBERED EYES MOSTLY HAVE A WIDE ANGLE WHERE AS ANGLE CONTOUR OF THE SHALLOW CHAMBERED EYE TENDS TO BE NARROW.

• WHEN ANGLE BETWEEN IRIS AND TRABECULAR MESH WORK IS BETWEEN

20-45degrees-WIDE ANGLE <20degrees-NARROW ANGLE

• MAJOR CONTRIBUTION OF GONIOSCOPY IS DISTINGUISHING OPEN ANGLE FROM ANGLE CLOSURE GLAUCOMA.

• GONIOSCOPIC LANDMARKS OF CHAMBER ANGLE FROM ANTERIOR TO POSTERIOR ARE

1.SCHWALBES LINE 2.TRABECULAR MESHWORK 3.SCLERAL SPUR

4.CILIARY BODY,IRIS PROCESS 5. PUPIL&IRIS

1.SCHWALBE’S LINE OR RING

• CONDENSATION OF COLLAGEN TISSUE THAT MARKS THE TERMINATION OF DESCEMENTS MEMBRANE OF CORNEA AND MOST ANTERIOR EXTENSION OF MESHWORK.

• IT IS NOT VISIBLE IN HEALTHY YOUNGS OR WITH LITTLE OR NO PIGMENTATION,VISIBLE ONLY IN PIGMENTED WHICH IS COMMON IN OLDER OR DISEASED PEOPLE

• IN SLIT LAMP EXAMINATION-SEEN IN LIMBAL CIRCUMFERENCE AS A HAZY ZONE OF THE INNER CORNEAL SURFACE BY CORNEAL WEDGE TECHNIQUE.

• INDIRECT CONTACT LENS-THE CORNEAL PARALLELEPIPED OF SLIT LAMP COMES TOGETHER AT THIS POINT.

• KOEPPE CONTACT LENS-TRANSLUCENT/WHITE LEDGE THAT PROJECTS INTO ANTERIOR CHAMBETR

• IT IS AN IMPORTANT LANDMARK WHEN PERFOMING GONIOTOMY,IN THAT THE INTERNAL INCISION IS MADE JUST POSTERIOR TO SCHWALBE’S LINE.

• IT IS ALSO IMPORTANT BCOZ NORMAL VESSELS AND TISSUES WILL NOT PASS IT SOMETIMES PATHOLOGICAL NEOVASCULARISATION AND SYNECHIA MAY PASS IT UP TO CORNEA.

• VARIATIONS LIKE EMBROYOTOXON POSTERIUS IN WHICH SCHWALBES RING MAY BECOME PROMINENT WITH APPEARANCE OF A LEDGE.

2.TRABECULAR MESHWORK

• IT CONSISTS OF MANY COLLAGEN FIBRES COATED WITH ENDOTHELIUM,LIES BETWEEN SCHWALBE’S LINE AND SCLERAL SPUR,THROUGH WHICH AQUEOUS HUMOR FLOWS INTO SCHLEMMS’S CANAL.

• GONIOSCOPICALLY IT APPEARS AS IRREGULAR ROUGHENED SURFACE,IN CHILDHOOD IT IS GLISTENING,TRANSLUCENT LIKE SEMITRANSPARENT GELATIN WITH STIPLED SURFACE,WITH INC IN AGE TRANSPARENCY DECREASES.

• EXAMINERS GAZE SHOULD BE PARALELL TO IRIS AS NEARLY AS POSSIBLE

IN INDIRECT GONIOSCOPY SUCH AS ZIESS LENS-HAVING THE PATIENT LOOK AWAY FROM VIEWING MIRROR GIVES AN OPTIMAL VIEW OF THE MESHWORK IN WIDE ANGLED EYES,

WHERE AS IN NARROW ANGLED EYES CONVEX PLANE OF IRIS FORCES A MORE OBLIQUE VISUALISATION WHICH ALLOW ANGLE RECESS TO BE SEEN WITH SOMEWHAT FORESHORTENED AND DISTORTED APPEARANCETO MESHWORK.

• FUNCTIONALLY IT IS DIVIDED INTO TWO PARTS- 1.FUNCTIONAL 2.NON FUNCTIONAL.• IT HAS THREE LAYERS- 1.UVEOSCLERAL TRABECULUM 2.CORNEOSCLERAL TRABECULUM. 3.JUXTRA CANALICULAR/CRIBRIFORM TRABECULUM• DUE TO CHANGES OF EXTRACELLULAR MATRIX AND CELLS IT IS THE

REGION OF INCREASED RESISTANCE IN PRIMARY OPEN ANGLE GLAUCOMA.

• IT IS ALSO NOT EASY TO FIND IN CHILDREN AND WITHOUT PIGMENT.

• THIS LAYER IS IMPORTANT FOR SURGICAL PROCEDURES LIKE GONIOTOMT,IMPLANTATION OF STENTS,EXCIMER LASER TARGETTING IT

• LASER THERAPY-ARGON LASER TRABECULOPLASTY ,SPOTS HAVE TO BE LOCALISED EXACTLY AS POSSIBLE BETWEEN FUNCTIONAL AND NONFUNCTIIONAL PARTS

• IF TM IS COVERED BY IRIS TISSUE-ANGLE CLOSURE• IN AGING AND DISEASE PROCESS-TRABECULAR PIGMENT

BAND WHICH TENDS TO BE DENSER IN LOWER ANGLE

• SCHLEMMS CANAL RUNS CIRCUMFERRENTIALLY BETWEEN CORNEA AND SCLERA DRAINING AQUEOUS HUMOR VIA COLLECTOR VESSELS TO THE EPISCLERAL AND CONJUNCTIVAL VEINS

• THIS IS VISIBLE ONLY WHEN FILLED WITH BLOOD Ex-HYPOTONIA BULBI , RESORPTION OF HYPHEMA, FISTULA OF CAROTIS IN SINUS CAVERNOSUS, STURGE WEBER SYNDROME,

SEVERAL DISEASES INVOLVING INCREASE IN EPISCLERAL VENOUS PRESSURE.

• 75-90% OF AQUEOUS HUMOR PASS THIS WAY,A CONVENTIONAL OUTFLOW,PRESSURE DEPENDENT & IOP IS HIGHER THAN PRESSURE IN EPISCLERAL VEINS

3.SCLERAL SPUR• IT IS A RIDGE OF COLLAGEN TISSUE WHICH IS THE

MOST ANTERIOR PROJECTION OF SCLERA.• MOST IMPORTANT LANDMARK THAT APPEARS

WHITE AND BRIGHT&MIGHT BE INVISIBLE DUE TO FARWARD BOWING OF THE IRIS(THEN ANGLE CLOSURE IS POSSIBLE).

• IT IS THE POINT OF ATTACHMENT OF CILIARY BODY,POINT OF TERMINATION OF MOST OF IRIS PROCESS&FORMS POSTERIOR CONCAVITY OF SCLERAL SULCUS

• PRINCIPAL SITE OF CYCLODIALYSIS PROCEDUERS IN WHICH AN AQUEOUS OUTFLOW PATHWAY IN THE SUPRACHOROIDA SPACE WAS CONSTRUCTED BY SEPERATING CILIARY BODY FROM SCLERAL SPUR

4.CILIARY BODY BAND,IRIS PROCESS,SYNECHIAE

• AT BIRTH ANGLE RECESS WHICH IS BEYOND IRIS ROLL IS INCOMPLETELY DEVELOPED,BY 1YR OF AGE FORMS A CONCAVITY INTO THE ANTERIOR SURFACE OF CILIARY BODY.

• APPEARS AS DENSELY PIGMENTED BAND DEEP TO TRABECULAR SURFACE.

• IRREGULAR THREAD LIKE FIBRES OF ANTERIOR IRIS STROMA SOMETIMES ARBORIZE ACROSS ANGLE RECESS CALLED AS IRIS PROCESS.

• GONIOSCOPICALLY SEEN TO TERMINATE NEAR THE SPUR,LARGE PROCESS REPRESENT INCOMPLETE EMBROYOLOGICAL SEPERATION OF IRIS FROM ANGLE WALL&SEEN IN PATHOLOGICAL CONGENITAL SYNDROME OF AXENFELD

SL-SCHWALBE’S LINE;SS-SCLERAL SPUR;CBB-CILIARY BODY BAND;TM-TABECULAR MESHWORK

IRIS PROCESS(IRIS STROMAL FIBRES THAT TERMINATE NEAR SPUR)

• BLUE EYES-LIGHT GREY&DIFFICULT TO SEE• BROWN EYES-PIGMENTED&PROMINENT

AGAINST A LIGHT BACKGROUND OF SCLERAL SPUR

• SOMETIMES GONIOSCOPIST MAY MISITERPRET IRIS PROCESS AS PERIPHERAL ANTERIOR SYNECHIAE

IRIS PROCESS• SYNCITIAL SHEETS THAT

CLOSELY FOLLOW CONCAVITY OF ANGLE RECESS& USUALLY ALLOW A VIEW OF ANGLE RECESS BEHIND,UNLESS THEY ARE EXTRAORDINARLY DENSE

SYNECHIAE• ACTUAL ADHESIONS OF IRIS

TISSUE THAT COVER&OCCLUDE VARIABLE AMOUNTS OF ANGLE.

• CAN INSERT LOW AT LEVEL OF SCLERAL SPUR(AFTER LASER TRABECULOPLASTY),AS HIGH AS SCHWALBE’S LINE OR BEYOND(IRIDOCORNEAL ENDOTHELIAL SYNDROME).

5.PUPIL &IRIS • IT IS BEST TO START GONIOSCOPY BY LOOKING AT PUPIL FOR

RAPID ORIENTATION.• ANTERIOR LENS SURFACE CAN BE OBSERVED FOR FOCAL

OPACIFICATION(GLAUCOMAFLECKENS)OF ANT LENS &FOR POSTERIOR SYNECHIA.

• THIS POSITION IS EXCELLENT FOR VIEWING WHITE DANDRUFF LIKE FLECKS OF EXFOLIATION ON THE PIGMENT AT THE POSTERIOR EDGE OF PUPIL(EXFOLIATION SYNDROME).

• IRIDODONESIS IS PRESNT TO A SMALL DEGREE IN SOME DEEP CHAMBERD NORMAL EYES&EASILY OBSERVED IF OF A PATHOLOGICAL DEGREE

• THREE MAIN FEATURES TO BE OBSERVED IN IRIS1.CONTOUR-FLAT IN DEEP ANTERIORCHAMBER,CONVEX IN EYES WITH SHALLOW A.C.2.INSERTION-DESCRIBED IN REFERENCE TO STRUCTURES WITH IN

ANGLE RECESS -AT THE LEVEL OF UPPER TRABECULAR

MESHWORK&SCHWALBE’S LINE-AT THE LEVEL OF FILTERING TRABECULAR MESHWORK JUST

BELOW SPUR-BELOW SPUR IN CILIARY BODYOR DEEP POSTRIORLY IN THE CILIARY BODY

VARIOUS LEVELS OF IRIS INSERTION,CAN BE DETERMINED BY INDENTATION GONIOSCOPY

3.ANGULATION –BETWEEN IRIS INSERTION ANS SLOPE OF INNER CORNEA IN THE ANGLE IN APPROXIMATE STEPS OF 10degrees.

LASTLY ABNORMALITIES SUCH AS NEOVASCULARISATION,HYPOPLASIA,POLYCORIA SHOULD BE NOTED