Gonio Assessment

Question 1

Classification systems of gonio

Answer 1

1. Scheie’s
2. Schaffer
3. Spaeth

Question 2

Scheie’s classification

Answer 2

wide open = all structures visible

grade 1= hard to see over iris root into recess

grade 2 = ciliary band obscured

grade 3 = posterior trabeculum osbcured

grade 4 = only schwalbe’s line visible

more structures visible = less likely risk for angle closure

Question 3

Shaffer’s classification

Answer 3

based on angular width of angle recess

A grade 4 = 45-35 angle, wide open (impossible to close)

B grade 3= 35-20 angle, wide open (impossible to close) moderately narrow

C grade 2 = 20 angle, narrow

D grade 1 = less than 10 angle, extremely narrow partially or totally closed

slit = slit angle, narrowed to slit, probably to close

0 angle = closed

Question 4

spaeth classification

Answer 4

system that grades 3 major features of angle anatomy:
1) level iris insertion:
a = anterior (iris inserts anterior to schwalbe’s line)
b = behind schwalbe’s line (anterior to posterior limit of trabecular meshwork, b/n schwalbe’s line and SS)
c = sclera (posterior to scleral spur, scleral spur is visible)
d = deep (into ciliary body)
e = extremely deep (into ciliary body)

2) angular width: estimated angle formed between a line tangential to trabecular meshwork and line tangential to iris surface surface about one third of way from periphery

3) iris configuration (older):
R - regular or flat configuration
S - steep curvature or bombe
Q - queer or concave curvature

3) Iris configuration (newer):
b - bowing anteriorly (grade bowing 1 - 4 plus)
p - plateau configuration
f - flat configuration
c - queer or concave posterior bowing

also grades pigment in posterior pigmented meshwork in the 12 position on a scale of 0-4 +

and the type of number of iris processes

also proposed noting: peripheral adhesions, blood in angle recess or schlemm’s canal, abnormal (neovascularization) or prominent blood vessels, angle cleavage (tears, disinsertion, angle recession), particles, atrophic changes

Question 5

plateau iris

Answer 5

van herick typically appears narrow

assoc - relatively uncommon form of primary angle closure glaucoma

caused by large or anteriorly positioned ciliary processes that push the peripheral iris forward

indentation gonio - sine wave or double hump sign

Question 6

spaeth’s classification notation example

Answer 6

(B) D 25 p

B = optical insertion b/n schwalbe’s line and scleral spur

D = anatomic iris insertion deep with ciliary body visible

25 = narrow angular approach of 25 degrees

P = plateau iris configuration

D40f = open angle, normal for caucasian

C40f = open angle, normal for asian

C25p = plateau iris, requires theapy

E40f = angle recession patient

E40c = reverse pupil block

C15b3+ =worrisome narrow angle

(B)D 10 b3+ = optical closure, indents open

B20b2+ = angle closure (impending AC)

Question 7

slit lamp gonio guidelines

Answer 7

examine eye and obtain iop before gonio, disenfect lens, usually performed on undilated pupil, always compare right eye to left, check eye post-procedure, complete dilated exam, angles appear narrow but safe to dilate (examine again)

Question 8

factors that affect anterior chamber angle recess angular width

Answer 8

iris insertion site

iris thickness and rigidity

lens thickness (age, medication, blood sugar)

lens position (medication, accommodative state, changes in ciliary body)

ciliary body thickness (inflammation, effusion, congestion)

pupil size (light, accommodation, medications, sympathetic and parasympathetic tone)

Question 9

iris insertion sites

Answer 9

cornea: iridocorneal edothelial syndrome (ICE), posterior polymorphous dystrophy, neovascular glaucoma (NVG), previous postoperative flat chamber, iris in limbal or scleral wound

scwalbe’s line: angle closure

trabecular meshwork: congenital glaucoma

anterior trabecular meshwork: angle closure

scleral spur: hyperopia, narrow angle or plateau iris, early creeping angle closure, or trabeculogniodygensis

ciliary body band: normal, emmetropia, myopia

beyond ciliary body band: w/ w/o scarring to more anterior levels - angle recession

iris root detached in one region: iridodialysis

ciliary muscle detached from scleral spur: cyclodialysis

variable insertion site: peripheral anterior synechiae or angle recession

Question 10

recording

Answer 10

last visible structure: function and anatomy insertion of the iris root

angular width (in degrees): approach to the angle

contour of the iris face: grade any bowing

grade pigment (PTM):
0= none
1= faint (trace)
2= average (mild)
3= heavy (mod)
4= very heavy (dense)

any abnormal structure or substance (synechiae, exfoliation flecks, neovascularization, structual abnormality (recession etc))

Question 11

optical coherence tomography

Answer 11

oct useful in assessment of AC - visante OCT

Question 12

UBM - ultrasound biomicroscopy

Answer 12

used to assess angles

Question 13

plateau iris

Answer 13

note peripheral iris configuration (double hump or sinusoidal picture)

before and after dilation

Question 14

3 mirror lens - exam of posterior segment

Answer 14

the other mirrors can be used to evaluate the retina

center lens - concave lens, used to neuralize refractive error of the eye, used to view post. pole to vortex veins, may also be used to assess the vitreous, 9 - 12 DD radius

equatorial mirror - 73 degree angle to iris plane, trapezoidal in shape, called trapezoid or “equatorial” mirror, used to visualize the equatorial area of the retina

peripheral mirror - 67 degree angle to iris plane, rectangular in shape, used to view from anterior equator to posterior ora serrata, 3 DD area

thumb nail mirror - 59 degree angle to the iris plane, thumb nail shaped, used to view peripheral retina to ora serrata and vitreous base, anterior chamber angle