Gonio structures

Question 1

Importance of gonio?

Answer 1

to check and view optic nerves and glaucoma

and observe angles

Question 2

function of angle

Answer 2

aqueous production and aqueous outflow

Question 3

Review: van herick technique grades

Answer 3

Grade 4: aacd >= ACT

Grade 3: aacd 1/2 - 1/3 ACT

grade 2: aacd 1/4 act

grade 1: aacd < 1/4 act

Question 4

Gonio Principles

Answer 4

Critical angle: light which comes from the anterior chamber angle (ACA) usually undergoes total internal reflection. A viewer cannot observe angle with just direct ophthalmoscope or slit lamp

Question 5

General concepts

Answer 5

superior angle generally the narrowest

inferior the widest

greatest pigment generally in the inferior angle

Question 6

factors affecting angle width - chamber depth

Answer 6

refractive error: myopes and emmetropes have wider angles than hyperopes

age: angle narrower with age
race: asians smaller angles
cataract: lenticular swelling makes chamber shallow
aphakia: iris flattens

peripheral iridectomy: alllows iris to lie flatter/angle wider

trauma: surgical, accidental

congenital abnormalities

Question 7

anatomy of the anterio chamber angle

Answer 7

posterior wall: root of the iris

angle recess: the longitudinal bundles of the ciliary muscle

anterior wall: scleral spur, trabecular meshwork, schwalbe’s line, schlemm’s canal (behind the trabecular meshwork) (acronym: I Can’t See This Stuff)

Question 8

Iris

Answer 8

pupillary ruff, collarette, crypts

contour: slightly convex (average adult, hyperope)
flat: post iridotomy, aphakia, pseudphakia

slightly concave: myopes and aphakes

abnormal: pigment disperson syndrome

plateau iris configuration

Question 9

Roll of Fuch’s

Answer 9

Largest roll of the iris

last roll of the iris

plateau iris syndrome: a feature of this syndrome an abnormally prominent last roll

Question 10

root of the iris

Answer 10

posterior border of the angle

fairly flat

inserts cil body unevenly, creating scaloped edge

thinnest portion of the iris

Question 11

ciliary band

Answer 11

forms angle recess

anterior aspect of ciliary muscle

pigmented structure and is typically gray to black

width of the band depends on level of iris insertion

consistent width, not usually wider than TM

Question 12

Scleral spur

Answer 12

seen as white/grayish white line

projection of collagen fibers from inner sclera

represents most anterior portion of sclera

may be obsured by iris processes vaulting over it pigment

trabeculae beams attach at anterior edge

ciliary body muscle fibers attach posteriorly

Question 13

trabeculum

Answer 13

spans anteriorly from end of descemet’s membrane at schwalbe’s line posterior to blend with scleral spur

typically light to dark brown (pigment color vary)

appears as intricate latticework

may appaear translucent because of spaces by drainage system

consists of crisscrossing collagen fibers covered by endothelium

bridges scheral sulcus in schlemm’s canal

Question 14

Trabeculum - 2 portions

Answer 14

anterior: non-pigmented, non-filtering (b/w post. portion and SL)
psterior: more pigment, filtering, inc. pigmentation with aging and disease processes, skin and hair color have little correlation with trabecular pigment

Question 15

Schwalbe’s line

Answer 15

most anterior portion of the angle

represents end of descemet’s membrane

site of transition between transparent corneal tissue and off-white translucent tissue of scleral

transition of steeper corneal surface to flatter curvature of angle recess and sclera

appearance: too faint, but sometimes appears as thin white line

corneal light wedge: cornea will appear in 3D, schwalbe’s line will collapse to 2D

Question 16

Schwalbe’s line

Answer 16

sampaolesi’s line: pigmented schwalbe’s line

posterior ebryotoxon: SL is prominent and anterior (normal varient, may also be associated with abnormal structure such as axenfeld-rieger syndrome

Question 17

canal of schlemm

Answer 17

located behind TM

not normally visible

blood in schlemm’s will appear as pink band

Question 18

iris process

Answer 18

iris process bridge the angle recess from ant. iris surface to TM usually in scleral spur area

process are pigmented in brown iridies

must be differentiated from anterior synechiae

may be broken with traumatic angle recession

Question 19

Iris process vs. anterior synechiae

Answer 19

iris process: fine, extend scleral spur, follow concavity of recess, underly structures seen, iris moves with identation, broken with angle recession

synechiae: broad, extend beyond scleral spur, bridge concavity of recess, obscure structures, resist movement, intact

Question 20

abnormal structure: evidence of trauma

Answer 20

angle recession: rupture cil body face, resulting in tear between longitudinal and circular fibers of ciliary muscle

b= cyclodialysis - creation of communication b/n anterior chamber of eye and suprachoroidal space (glaucoma)

c= irdodialysis - sepration of iris from ciliary attachment

d = meshwork tears

Question 21

pigment dispersion syndromekruckenberg spindle

Answer 21

pigment on endothelium of cornea, typically elongated vertical pattern

iris defects, pigment on iris surface and pigment in angle

Question 22

pseudoexfoliation syndrome

Answer 22

systemic disease with primary ocular manifestation characterized by deposition of whitish grey protein on lens capsule, iris, ciliary body, zonules, corneal endothelium and trabecular meshwork.

Question 23

gonio clinical correlation

Answer 23

corneal: pigment, blood staining, trauma

anterior chamber: inflammation, blood

lens: exfoliation, pigment, catarct, subluxation
vitreous: inflammation, blood, prolapse
retina: ischemia, inflammation, trauma

optic nerve: Glaucomatous cupping, atrophy

Question 24

gonio indications

Answer 24

assesss depth of anterior chamber anlge

patient with high IOP

patients with glaucoma

signs of pigmentary glaucoma

history of ocular trauma

inflammation of suspicion of synechia

any ocular ischemia rubeosis iridis (diabetic retinopathy, hypertensive retinopathy, central retinal artery occulsion, central retinal vein occlusion, branch retinal vein occlusion)

when masses seen/suspected (intumescence, dislocation, or subluxation of crystalline lens, iris atrophy, evidence of ocular trauma observed, congenital anterior chamber angle anomalies)

Question 25

gonio contraindications

Answer 25

perforated globe, intraocular fb, intraorbital fb, trauma (acute), recent ocular surgery, corneal insult, sensitivity to pharmaceuticals, infection