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OPT 2 10 GONIOSCOPY EXAM QUESTIONS AND CORRECT
ANSWERS 100 % CORRECT!!
What is gonio used for? visual inspection of the anterior chamber angle through a gonio prism
What are indications for gonio? -determining dilation safety for van herick grade 2 or less
-high or asymmetric IOP (>24 or asymmetry ≥3)
-diagnosis and differentiation of glaucoma
-treatment of acute angle closure
-evaluating anterior synechiae in uveitis or trauma or angle closure
-concern for neovascularization
-evaluating in tumor, foreign body, congenital anomaly, surgical procedure or implant
-procedures
What procedures can gonio be used in? -laser trabeculoplasty -iridoplasty -peripheral iridotomy -MIGS (micro-invasive glaucoma surgery)
When is gonio contraindicated? -acute trauma (especially if corneal defect or hyphema) -possible penetrating ocular injury -recent intraocular surgery -severely cloudy cornea
What are possible complications associated with gonio procedure? -conjunctival injections -conjunctival hyphema -corneal abrasion -corneal epithelial disruption
What are the three methods of gonio? -direct (erect view) -indirect (inverted view of opposite angle) -dynamic (indentation, requires a corneal lens)
Describe the characteristics of indirect viewing system? -light rays reflected by mirror in the contact lens -light leaves lens at nearly right angle to the contact lens air interface -alters the angle of refletion by 180° using the mirror
What is the direct gonioscopy procedure used for? primarily used in surgery
What is the view when using direct gonio? 120° panoramic, upright and direct view
What type of lens is used for direct gonio? -dome shaped, mirrorless lens -steeper external curvature in comparison to cornea -does not allow the critical angle to be exceeded
What kind of image if formed with indirect gonio using the 3 mirror gonioprism? image is flipped once depending on location of the mirror
What is the view for 4 mirror gonioscopy? see image
What type of gonio is most often performed in the optometrist clinic? indirect
What is the benefit of having more mirrors in the gonioprism? more mirrors means less rotation is needed
What are the three mirrors used for on the 3M gonioprism? -60° mirror is used for AC viewing -66° mirror is used to view peripheral retina -76° mirror is used to view the mid periphery
note that the greater the angle, the closer viewing is to the posterior pole
What viewing degree are mirrors in the 4M gonioprism set up for? -64° viewing angle to view the anterior chamber angle
What is the average anatomical corneal diameter? 11-22 mm
-quick assessment -no lens rotation -compression/indentation gonio can be performed -need anesthetic only
What are disadvantages to a corneal lens? -decreased quality of image -transient image -poor stabilization of lens and image -pressure on lens can cause artificial widening of angle OR corneal folds/wrinkles
What is dynamic gonioscopy? compression or indentation gonio; it is done when there are no structures visible on indirect gonio
How does dynamic gonio work? gentle pressure on cornea forces the angle to open (peripheral iris moves posteriorly and aqueous humor is forced into the angle) to view more angle structures
What can dynamic gonio differentiate between? appositional closure (iridotrabecular contact) and synechial closure (peripheral anterior synechiae)
What does "I can see the line" refer to? -peripheral Iris
-Ciliary body
-Scleral spur
-Trabecular meshwork
-schwalbe's Line
describes the anatomy of the angle from most posterior to most anterior
What is the average anterior chamber angle depth? 3.4 mm
______________ have a greater angle depth than hyperopes. axial myopes
Do men or women generally have a greater angle depth? men
What does an iris flat approach look like? overall flat (see image)
What does a convex iris approach look like? -iris is bowed towards cornea -risk of angle closure is possible (see image)
What does a concave iris approach look like? -iris bowed away from the cornea -risk of pigmentary dispersion (see image)
What does a plateau iris approach look like? -convex at insertion then flattens towards pupil -due to anteriorly positioned ciliary body processes pushing the peripheral iris forward -risk of angle closure is possible (see image)
What are iris processes? benign finding in 30% of normal eyes that are the extension of the iris that inserts into the CB, SS, or rarely in TM
How are iris processes differentiated from peripheral anterior synechiae? PAS have broader appearance and extends past the TM (blocking outflow)
What are examples of iris abnormalities in the angle? -peripheral anterior synechiae -iris or angle neovascularization -iridocorneal endothelial syndromes -peripheral laser iridotomy/iridectomy
What are peripheral anterior synechiae? -insert into Schwalbe's line or peripheral cornea -blocks aqueous outflow in that area
What are normal blood vessels in the angle/ on iris? circumferential vessels at base of iris (which never attach to angle anterior to scleral spur) and radial iris vessels
What is the ciliary body band? anatomically the posterior most structure (located immediately posterior to the scleral spur)
iris inserts into the anterior ciliary body at variable levels
What is the primary site of aqueous outflow? trabecular meshwork (85% conventional outflow)
Where does Schlemm's canal exit? internally to the posterior trabecular meshwork
What are possible variations/abnormalities of trabecular meshwork? -increased pigmentation -pink/red tinge=blood
What can increased pigment of the PTM be attributed to? -can be normal -aging (less pigmented and smooth in infancy) -pigment dispersion -pseudoexfoliation -trauma -uveitis -ocular surgery
Why may the TM appear pink or red? increased episcleral venous pressure -can be normal/idiopathic
-can result from too much pressure in gonio -intraorbital or intracranial vascular anomalies
Does the anterior trabecular meshwork have pigment? no; appears to be whitish/off white
What is Schwalbe's line? white or translucent narrow line that signifies the start of the cornea (descemet's membrane)
it is the most anterior structure of the angle
What is Sampaolesi's line? Pigmented Schwalbe's line
can be idiopathic, can be pseudoexfoliative syndrome, or can be pigmentary dispersion syndrome
What is posterior embryotoxin? Anterior Displaced Schwalbe's Line; developmental anomaly resulting in discontinuous appearance
What is Axenfeld-Rieger Syndrome?
