BCSC Glaucoma Flashcards
What is a working definition of glaucoma?
A group of diseases that share a common characteristic optic neuropathy with associated visual field loss. Elevated IOP is one of the primary risk factors
What is the commonly accepted normal range for IOP?
10-22 mmHg
What are the 3 primary factors that determine IOP?
1) rate of aqueous production by ciliary body, 2) resistance to aqueous outflow across TM, 3) episcleral venous pressure
What is the most common cause of increased IOP?
increased resistance to aqueous outflow
What is a primary glaucoma?
A glaucoma not associated with known ocular or systemic disorders that cause increased resistance to aqueous outflow or angle closure.
Are primary glaucomas usually bilateral or unilateral?
bilateral
What is the presumed etiology of open angle glaucoma?
an abnormality in the TM ECM in the juxtacanalicular region
What is the estimated incidence of POAG?
2.4 million/year worldwide
What is the race ratio of POAG (African descent : Caucasian)?
4:1
What are the known risk factors for development of POAG?
1) elevated IOP, 2) advanced age, 3) decreased corneal thickness, 4) race, 5) FHx
What racial group has the highest known prevalence of PACG?
Inuit populations from Arctic regions. 20-40x higher than for whites, putting the prevalence at 2 - 4%.
What is the gender ratio of incidence of acute angle closure glaucoma?
4:1 female to male
In what age range is acute angle closure glaucoma most common?
55-65 years
Is the AC deeper or shallower in women than in men?
shallower AC in women
Is the AC deeper or shallower in hyperopes than myopes or emmetropes?
shallower in hyperopes
What is the prevalence of glaucoma in siblings of patients with POAG?
10%
What is the Goldmann equation for IOP?
An equation summarizing the relationship between aqueous production (F), outflow facility (C), and episcleral venous pressure (P_v).
P_0 = (F/C) + P_v
Where is aqueous humor formed?
In the ciliary processes, each of which is composed of a double layer of epithelium over a core of stroma and a rich supply of fenestrated capillaries. In particular, it is thought that aqueous production is localized to the inner non-pigmented epithelial cells.
How many ciliary processes are there?
approximately 80
What are the two epithelial layers covering the ciliary processes?
1) Outer pigmented, 2) inner non-pigmented
How are the ciliary epithelial layers oriented?
apical sides face each other
Into which chamber do the inner non-pigmented epithelial cells protrude?
posterior chamber
By what are the ciliary epithelial layers joined?
tight junctions
What is the common unit of measure for aqueous flow?
microliters per minute
What is the common unit of measure for episcleral venous pressure?
mm Hg
What are the 3 processes by which aqueous humor is produced?
1) active secretion (takes place in double-layered ciliary epithelium)
2) ultrafiltration
3) simple diffusion
Does active secretion require energy?
yes
What is ultrafiltration?
a pressure-dependent movement along a pressure gradient.
How does ultrafiltration occur in the ciliary processes?
Difference between capillary pressure and IOP favors fluid movement into the eye, whereas oncotic gradient between the two resists fluid movement.
What is diffusion?
the passive movement of ions across a membrane related to charge and concentration
Does aqueous contain protein?
Tiny amount (half of which is albumin), but it is nearly protein-free (1/200 to 1/500 the amount found in plasma). This allows for optical clarity.
What are the major differences in ion concentrations between aqueous and plasma?
excess H+, Cl-, ascorbate, HCO3- deficit relative to plasma
Does aqueous contain carbonic anhydrase?
yes
What is the average rate of aqueous production?
2.0 microL/min
The the aqeuous (aq) composition change as it flows from posterior chamber to anterior chamber?
Yes
Which classes of drugs suppress aq formation?
1) CAIs
2) Beta blockers
3) alpha-2 agonists
What percentage of aq volume is turned over in 1 minute on average?
1%
What physiologic factors affect the rate of aq formation?
1) integrity of blood-aqueous barrier
2) blood flow to the ciliary body
3) neurohumoral regulation of vascular tissue and the ciliary epithelium
What are the two primary mechanisms of aq outflow?
1) pressure-dependent outflow = trabecular outflow
2) pressure-independent outflow = uveoscleral outflow
What factors affect the outflow facility (C) of aq in the eye?
1) age
2) surgery
3) trauma
4) medications
5) endocrine factors
What are the 3 parts of the TM?
1) uveal
2) corneoscleral
3) juxtacanalicular
Which of the 3 parts of the TM is thought to the be the major site of outflow resistance?
the juxtacanalicular meshwork, which actually forms the inner wall of Schlemm’s canal
Of what does each layer of the TM consist?
a collagneous connective tissue core covered by a continuous endothelial layer covering
How does the TM allow pressure-dependent outflow?
it acts as a one-way valve that permits aq to leave the eye, but limits flow in the other direction
What is the average number of trabecular cells per eye?
200,000 to 300,000
What effect does laser trabeculoplasty have on cell division in the TM?
LT induces cell division in the TM
What is the lining of Schlemm’s canal?
endothelium
what is the average diameter of Schlemm’s canal?
370 microns
To where does fluid in Schlemm’s canal drain?
to the episcleral veins (–> anterior ciliary and ophthalmic veins), through a complex system of vessels
What is the involved in pressure-independent (uveoscleral) outflow?
aq passage from AC into ciliary muscle and then into supracilary and suprachoroidal spaces
What percent of total aq outflow is thought to be uveoslceral?
15%
What can be done/used to increase uveoscleral outflow?
1) cycloplegia, 2) adrenergic agents, 3) prostaglandin analogs, 4) cyclodialysis
What is tonography?
the measure of the ease with which aqeuous can leave the eye (outflow facility)
What factors affect episcleral venous pressure?
1) alterations in body position, 2) diseases of the orbit, head, and neck obstructing venous return to the heart, 3) AV fistulae
What is the normal range for episcleral venous pressure values?
8-10 mmHg
What effect doe facial hemangiomas and thyroid ophthalmopathy have on episcleral venous pressure (EVP)?
They increase EVP
Is distribution of IOP gaussian?
No, it is skewed toward higher pressures
What is the sensitivity of IOP > 21 as a test for glaucoma?
about 50%
What are known factors affecting IOP?
1) time of day
2) heartbeat (cardiac cycle)
3) respiration
4) exercise
5) fluid intake
6) systemic medications
7) topical drugs
What is the magnitude of diurnal variation in IOP in normal individuals?
2-6 mmHg
A magnitude of diurnal variation in IOP greater than what is indicative of glaucoma?
10 mmHg
What is the diameter of the corneal circle flattened by a Goldmann applanation tonometer?
3.06mm
Why is the diameter of 3.06mm used by the Goldmann applanation tonometer?
It is presumed that at this diameter:
1) the resistance of the cornea to flattening is blaanced by the capillary attraction of the tear film meniscus for the tonometer head
2) IOP = the flattening force * 10 (i.e., easy calculation)
Does applanation tonometry give falsely high or low readings in corneal edema?
Falsely low
Does applanation tonometry give falsely high or low readings in corneal scar?
Falsely high
Does applanation tonometry give falsely high or low readings over a soft contact lens?
Falsely low
Does applanation tonometry give falsely high or low readings in high central corneal thickness?
Falsely high
What did the OHTS find with regard to CCT?
thinner central cornea was strong predictive factor for development of glaucoma
What historical aspects are relevant for a patient suspected of glaucoma?
pain, redness, halos around lights, alteration of vision, loss of vision
What are 4 disorders with facial manifestations that can be associated with glaucoma?
1) tuberous sclerosis, 2) NF, 3) JXG, 4) Oculodermal melanocystosis
What are Haab’s striae?
breaks in Descemet membrane associated with increased IOP
What corneal endothelial findings can be associated with secondary glaucomas?
1) Krukenberg spindle (pigmentary glaucoma)
2) Exfoliation material (exfoliative glaucoma)
3) KPs (uveitic glaucoma)
4) Guttae (Fuchs)
5) Vesicular lesions (PPMD)
6) Beaten bronze appearance (ICE syndromes)
What is the van Herick method for angle testing?
1) direct slit beam at 60 to cornea, just anterior to limbus
2) AC depth < 1/4 corneal thickness ON THIS VIEW => narrow angle
Should the iris be examined prior to or after dilation?
Prior to dilation
Why is gonioscopy required to visual the chamber angle?
Under normal conditions, direct visualization of the angle is not possible due to total internal reflection at the tear-air interface. The critical angle is 46 degrees.
What kind of image is provided by a goniolens?
An inverted and slightly foreshortened image of the opposite angle
What is the parallelopiped technique for angle assessment?
The examiner uses a narrow slit beam and sharp focus to elicit 2 linear reflections – one each from the external and internal corneal surfaces. The reflections meet at Schwalbe line.
Is Schelmm canal usually visible by gonioscopy?
No
In what situation does blood enter Schlemm canal?
EVP exceeds IOP
How does the Spaeth gonioscopic grading system differ from the Shaffer system?
The spaeth system includes a description of the peripheral iris contour, the insertion of the iris root, and the effects of indentation on the angle configuration
What is a Sampaolesi line?
A line of pigment deposition anterior to Schwalbe line seen in pigment dispersion syndrome
What are the gonioscopic criteria for diagnosing angle recession?
1) abnormally wide ciliary body band
2) increased prominence of scleral spur
3) torn iris processes
4) marked variation of ciliary face face width and angle depth in different quadrants
What is cyclodialysis?
separation of the ciliary body from the scleral spur
How does cyclodialysis appear on gonioscopy?
deep angle recess with a gap between the scleral spur and the ciliary body
What are the two components of the intraorbital optic nerve?
Anterior optic nerve and posterior optic nerve
What are the boundaries of the anterior optic nerve?
Retinal surface to exit of posterior aspect of globe
Are ganglion cell axons originating closer to the optic disc situated more centrally or peripherally in the optic nerve?
More centrally
What are the 4 divisions of the anterior optic nerve?
1) Nerve fiber
2) Prelaminar
3) Laminar (as in lamina cribrosa)
4) Retrolaminar
Which of the 4 divisions of the anterior optic nerve contains myelinated fibers?
Retrolaminar portion
Of what is the lamina cribrosa composed?
A series of fenestrated sheets of connective tissue and elastic fibers
What is the composition of connective tissue of the lamina cribrosa?
collagen primarily; also elastin, laminin, fibronectin
In which quadrants of the lamina cribrosa are fenestrations larger?
inferior and superior
What is the arterial supply of the anterior optic nerve?
entirely provided by 1 to 5 posterior ciliary arteries (derived from branches of the ophthalmic artery)
What is the circle of Zinn-Haller?
A non-continuous arterial circle within the perineural sclera
What is the venous drainage of the anterior optic nerve?
Exclusively through the central retinal vein
Where does loss of axons appear to start in glaucomatous optic neuropathy?
at the level of the lamina cribrosa, particularly at the inferior and superior poles of the disc
Do structural changes precede or follow functional changes in glaucomatous optic neuropathy?
Structural changes may precede detectable functional changes
What are the two primary theories of the mechanism of glaucomatous optic nerve damage?
1) Mechanical theory
2) Ischemic theory
What is the focus of the mechanical theory of glaucoma?
direct compression of axonal fibers due to distortion of the lamina cribrosa and resultant iterruption of axoplasmic flow –> death of RGCs
What is the focus of the ischemic theory of glaucoma?
Intraneural ischemia resulting from IOP-induced hypoperfusion or failure of vascular autoregulation.
What are the early changes of glaucomatous optic neuropathy?
1) generalized enlargement of the cup
2) focal enlargement of the cup
3) splinter hemorrhage
4) NFL loss
5) translucency of neuroretinal rim
6) development of vessel overpass
7) asymmetry of cupping (between eyes)
8) peripapillary atrophy
Asymmetry of the cup-disc ration of > 0.2 occurs in what percent of normal individuals?
< 1% of normal individuals
What is an acquired optic disc pit?
Deep localized notching, where the lamina cribrosa is visible at the disc margin
What type of illumination is most effective for viewing the NFL?
red-free
What are the two major purposes of obtaining visual fields in glaucoma?
1) identification of abnormal fields
2) quantitative assessment of normal or abnormal fields to guide follow-up
Is short-wavelength automated perimetry (SWAP) more or less sensitive than achromatic visual fields?
More sensitive for early glaucomatous changes in field
What are 4 methods other than SWAP (and other perimetric tests) to perform visual field testing?
1) contrast sensitivity
2) flicker sensitivity
3) VEP
4) ERG
What is an isopter?
A curve on a visual field representation connecting points with the same threshold
What are the 6 standard patterns of glaucomatous visual field defects?
1) generalized depression
2) paracentral scotoma
3) arcuate or Bjerrum scotoma
4) nasal step
5) altitudinal defect
6) temporal wedge
How does cyclotorsion of an eye affect perimetry?
defect may shift in location from where it would normally be expected
Which areas of the visual field are usually retained even in advanced glaucomatous visual field loss?
1) central field, 2) inferior temporal field
Can presbyopia affect perimetry?
Yes, it must be corrected to allow focusing at the appropriate distance for the test while avoiding a lens rim artifact
Pupils smaller than what diameter may create artifacts in visual field testing?
< 3mm
What is the Swedish interactive thresholding algorithm (SITA)?
An efficient threshold determination strategy that utilizes a prediction of the expected luminance threshold at a given test location based on age and neighborhood measurements to accelerate convergence to a threshold for each test location.
Should a suprathreshold test be used in a glaucoma suspect patient?
No, suprathreshold tests do not provide a good reference for future comparison. They can be used for screening of the general population, however.
Which parameters of a visual field test indicate the quality of testing?
1) % fixation losses
2) false positives
3) false negatives
What are 3 common artifacts seen on perimetry?
1) lens rim
2) incorrect corrective lens
3) cloverleaf field (characteristic of Humphrey 30-2, due to the test logic, when a patient stops paying attention)
What are 3 guidelines for identifying visual field progression?
1) Deepening of an existing scotoma is indicated by reproducible depression of a point within an existing scotoma by >= 7dB
2) Enlargement of an existing scotoma is indicated by reproducible depression of a point adjacent to an existing scotoma by >= 9 dB
3) Development of a new scotoma is indicated by the reproducible depression of a previously normal point in the visual field by >= 11 dB or 2 adjacent normal points by >= 5 dB
Should pupil size be recorded at the time of each visual field test?
Yes, to avoid incorrect interpretation due to miosis
What are adjunctive tests that can be performed to monitor a glaucoma patient (aside from visual fields)?
1) FA
2) pachymetry
3) EVP measurement
4) carotid vascular studies
5) ocular blood-flow measurements
6) ultrasound biomicroscopy
What are 4 disc findings indicative of glaucoma?
1) asymmetry of the neuroretinal rim or cupping
2) focal thinning or notching of the neuroretinal rim
3) disc hemorrhage
4) peripapillary atrophy of NFL
What were the primary findings of the OHTS?
1) topical ocular hypotensive medication delayed or prevented onset of POAG (60 month follow-up)
2) Risk factors for POAG: age, vertical and horizontal cup-disc ratio, pattern standard deviation, IOP, CCT (although not well controlled for race)
What was the primary finding of the Early Manifest Glaucoma Trial (EMGT)?
risk of progression of POAG reduced by 1/2 over 6 years with ocular hypotensive treatment
What were the primary findings of the Collaborative Initial Glaucoma Treatment Study (CIGTS)?
Initial therapy of medical therapy vs. glaucoma filtration:
1) similar visual field outcomes after 5 years follow-up
2) quality of life similar
What were the primary findings of the Advanced Glaucoma Intervention Study (AGIS)?
ALT - trabeculectomy (trab) - trab vs. trab - ALT - trab:
1) Patients of African descent had less visual field loss with ATT
2) Caucasian patients had less field loss with TAT
3) Lower IOP was associated with less visual field loss
4) Trab increased relative risk of cataract formation by 78%
5) Trab more effective in Caucasian patients than patients of African descent
6) ALT slightly more effective in patients of African descent
7) ALT failure was associated with younger age and higher IOP
Do patients with normal-tension glaucoma show a higher prevalence of vasospastic disorders?
Yes, with disorders such as migraine, Raynaud phenomenon, and autoimmune diseases
What did the Collaborative Normal Tension Glaucoma Study (CNTGS) find?
Reduction in visual field progression with IOP reduction greater than 30%
What are 2 commonly used categories for Normal-Tension Glaucoma (NTG)?
1) senile sclerotic – pale sloping of neuroretinal rim
2) focal ischemic – deep, focal, polar notching in neuroretinal rim
How do visual field defects in NTG tend to differ from those in POAG?
NTG has more central, focal, deeper defects than POAG. A dense paracentral scotoma encroaching on fixation is often seen in NTG as an initial defect.
What are 6 non-glaucomatous optic nerve diseases that mimic normal tension glaucoma (NTG)?
1) congenital anomalies of the disc
2) compressive lesions of the nerve
3) shock optic neuropathy
4) AION
5) Retinal disorders
6) optic nerve drusen
What were the criteria for initiating treatment for NTG in the CNTGS trial?
1) visual field loss threatening fixation
2) disc hemorrhage
3) documented visual field or optic nerve progression
What is a working definition of a glaucoma suspect patient?
One of the following findings in at least one eye:
1) optic nerve or NFL defect suggestive of glaucoma
2) visual field abnormality consistent with glaucoma
3) IOP consistently > 22 mmHg
What were the risk factors for development of glaucoma identified in the OHTS?
1) elevated IOP
2) low CCT
3) increased cup-disc ratio
What is the characteristic finding in exfoliation syndrome?
deposition of a distinctive fibrillar material in the anterior segment of the eye. The pattern is usually “target-like” (arc-shaped) at the inferior border of the anterior capsule of the lens
Is peripupillary atrophy with transillumination of the pupillary margin common in PXF?
Yes
Are eyes with PXF predisposed to zonular dehiscence?
Yes
What percent of cases of OAG are related to PXF in Scandinavian countries?
> 50%
Is an unusually large amount of postoperative inflammation with ocular surgery seen with PXF patients?
Yes
Where is a Sampaolesi line usually seen (in PXF)?
anterior to Schwalbe line in the inferior angle
How does a Krukenberg spindle differ from a Sampaolesi line?
While both are pigment depositions on the corneal endothelium, the Krukenberg spindle (Pigment dispersion) is vertical while the Sampaolesi line (PXF) is an arc in the inferior angle
What is a Zentmayer line?
pigment deposits on the zonular fibers and both anterior and posterior lens capsule near equator seen in Pigment dispersion
Are wide fluctuations in IOP seen in pigmentary glaucoma?
Yes
What stimulates pigment dispersion in pigmentary glaucoma?
1) exercise, 2) pupillary dilation
What are the 3 forms of lens related glaucomas?
1) Phacolytic
2) Lens particle
3) Phacoanaphylactic
What is the key feature of phacolytic glaucoma?
leakage of HMW protein from cataractous lens causes macrophages filled with this protein to obstruct the TM
What is the key feature of lens particle glaucoma?
Retained lens cortex after surgery (usually cataract surgery) or trauma leading to inflammation
What is the time to onset of lens particle glaucoma?
weeks to months or years
What is the key feature of phacoanaphylactic glaucoma?
Sensitization to one’s own lens, with resultant granulomatous inflammation and KPs
Is ciliary body hyper or hypo secretion usually seen in uveitis?
Hyposecretion. However, this is often outweighed by TM dysfunction
What two findings suggest iritis a a cause of IOP elevation?
1) KP
2) miotic pupil
What are the clinical features of Fuchs heterochromic iridocyclitis?
1) iris heterochromia due to loss of pigment in affected eye
2) stellate KPs
3) PSC
4) insidious
5) unilateral
Are steroids generally helpful in treating Fuchs heterochromic iridocyclitis?
No, but aq suppressants are usually effective.
What are 3 primary classes of causes of increased episcleral venous pressure?
1) AVM
2) Venous obstruction
3) SVC syndrome
Is hyphema associated with rebleeding usually smaller than the primary hyphema?
No, it is usually larger
What should be avoided in patients with sickle cell hemoglobinopathies (including sickle trait) when a hyphema is present?
1) Systemic carbonic anhydrase inhibitors (they lower pH of aq –> sickling)
2) dehydration
3) alpha-1 agonists (anterior segment vasoconstriction)
4) parasympathomimetics
In which situations is AC washout for hyphema justified?
1) children at risk of developing amblyopia
2) need to perform intraocular surgery
What blocks the TM in hemolytic glaucoma?
hemoglobin-laden macrophages
What blocks the TM in ghost cell glaucoma?
Ghost cells (degenerated RBCs lacking hemoglobin)
What is a common historical element in patients presenting with Ghost Cell Glaucoma?
prior vitreous hemorrhage with some prior disruption of hyaloid face
What is an angle recession?
A tear in the ciliary body between the longitudinal and circular muscle fibers
Are cohesive or dispersive viscoelastics more likely to cause a secondary elevation in IOP?
Dispersive
What are 3 forms of glaucoma related to IOL implantation?
1) uveitis-glaucoma-hyphema syndrome
2) secondary pigmentary glaucoma
3) pseudophakic pupillary block
What is UGH?
a form of secondary inflammatory glaucoma caused by chronic inflammation due to a malpositioned ACIOL
What is Schwartz-Matsuo syndrome?
blockage of TM by photoreceptor outer segments due to chronic rhegmatogenous retinal detachment
Is glaucoma common after PK?
Yes, due to TM distortion and progressive angle closure
What is the mechanism of elevated IOP due to steroids?
increased resistance to aqueous outflow in the TM
After how long can steroid-induced IOP elevation become permanent?
18 months
Can patients with high levels of endogenous steroids experience high IOP?
Yes, as is seen in Cushing syndrome
Is PACG the leading cause of bilateral blindness in the world?
Yes
In what part of the world is PACG the predominant form of glaucoma?
East Asia
What are the two conceptual mechanisms of angle closure?
1) pushing of iris forward from behind (e.g., pupillary block)
2) pulling of iris forward from the front (e.g., epithelial downgrowth)
What is the most frequent cause of angle closure?
pupillary block
What are the standard means by which to break pupillary block?
peripheral iridectomy or iridotomy
What is phacomorphic glaucoma?
glaucoma due to angle closure from an unusually large or intumescent lens
What percent of cases of primary angle closure are due to pupillary block?
90%
What are the risk factors for development of PACG?
1) race (Inuit, South Africa)
2) short axial length, small corneal diameter, small radius of curvature
3) age > 40
4) female : male is 3:1
5) FHx
6) hyperopia (may be axial length related)
What are 6 sings of acute angle closure?
1) high IOP
2) sluggish, irregular pupil
3) corneal epithelial edema
4) congested episcleral vessels
5) shallow AC
6) mild amount of AC cell and flare
How is dynamic gonioscopy helpful in the evaluation of angle closure?
can differentiate between reversible (appositional) or irreversible (synechial) causes
What are glaukomflecken?
characteristic small anterior subcapsular lens opacitis that can develop in the setting of iris ischemia
What medical therapy can be used in mid cases of acute angle closure?
cholinergic agents to induce miosis
Which agents should be avoided in angle closure?
alpha-1 agonists (can worsen iris ischemia and pupillary dilation)
What is the likelihood of developing an acute angle closure within the next 5-10 years in the fellow eye of an angle closure patient?
40-80%
What is present in chronic angle-closure glaucoma?
PAS
What are indications for laser iridectomy/iridotomy in a patient with narrow angles?
1) documented appositional or near appositional closure
2) PAS
3) increased segmental TM pigmentation
4) prior Hx of angle closure
5) positive provocative test
6) shallow AC (< 2mm)
7) strong FHx
What med can be used to reverse phenylephrin or ropicamide induced pupillary dilation rapidly (within 30 minutes)
0.5% dapiprazole solution
What is plateau iris?
a type of primary angle closure caused by anteriorly positioned ciliary processes, pushing the peripheral iris forward
What 3 treatments are used in patients with plateau iris?
1) iridectomy/iridotomy
2) long-term miotic therapy
3) laser peripheral iridoplasty (to reshape peripheral iris)
What medical treatment can be used for pupillary block in microspherophakia?
cycloplegia
What are 5 common causes of ectopia lentis?
1) trauma
2) Marfan
3) Homocystinuria
4) Microspherophakia
5) Weill-Marchesani syndrome
What are the two most common mechanisms of secondary angle closure without pupillary block?
1) inflammatory, hemorrhagic, or vascular membrane, band, or exudate in the angle, leading to PAS
2) forward displacement of the lens-iris diaphragm
What are the 3 most common causes of neovascular glaucoma?
1) DM
2) CRVO
3) Ocular ischemic syndrome
Is the prognosis poor for neovascular glaucoma?
Yes
What is the treatment of choice for iris neovascularization?
PRP
What are the 3 clinical variants of ICE syndrome?
1) Iris-nevus syndrome (Cogan-Reese syndrome)
2) Chandler syndrome
3) Essential iris atrophy
What appearance does the corneal endothelium have in each of the variants of ICE?
“beaten bronze”
What is the basic characteristic of the ICE syndromes?
Abnormal corneal endothelium leading to:
1) varying degrees of iris atrophy
2) secondary angle closure glaucoma
3) corneal edema
Which findings predominate in Chandler syndrome?
corneal and angle findings (minimal iris findings)
Which is the most common of the ICE syndromes?
Chandler syndrome (50% of all cases)
What percent of patients with ICE syndrome develop glaucoma?
50%
Where do PAS most commonly form in angle closure secondary to inflammation?
Inferiorly, as opposed to superiorly in primary angle closure
What is the usual context for the onset of aqueous mistirection?
1) post intraocular surgery
2) Hx of angle closure or PAS
3) with open angle after laser procedure
What is the presumed mechanism of aqueous misdirection?
anterior rotation of the ciliary body and posterior misdirection of the aqueous with relative block to aq movement elsewhere
What can sometimes be seen in the vitreous of a patient with aqueous misdirection?
“aqueous zones” that are optically clear
What is in the initial DDx of aq misdirection?
1) choroidal effusion
2) pupillary block
3) suprachoroidal hemorrhage
What is the medical management for aq misdirection?
cycloplegia, ocular hypotensive agents
What is the definitive surgical therapy for aq misdirection?
vitrectomy with AC deepening procedure
In what situation can epithelial downgrowth occur?
defect in corneal wound
What are the 3 forms of epithelial proliferatino seen in epithelial downgrowth?
1) pearl tumors of the iris
2) epithelial cysts
3) epithelial ingrowth over the TM
How can epithelial downgrowth be confirmed?
By white burns formed on epithelial membrane on the iris surface when using the argon laser
Can scleral buckling produce shallowing of the AC and angle closure?
Yes
Where should an iridectomy/iridotomy be placed when perfluorocarbons, air, or silicone oil are injected after a PPV?
inferiorly, to avoid apposition with the low-density injected substance that should rise to the superior part of the eye
Can topiramate result in angle closure?
Yes, by causing ciliochoroidal effusion resulting in anterior displacement of the lens-iris complex
Primary congenital glaucoma (PCG) accounts for what percent of congenital glaucomas?
50% - 70%
Is the etiology of PCG known?
No, but it is thought to represent a developmental anomaly of the angle structures, possibly due to developmental arrest in the late embryonic period
What are the characteristic findings of infantile glaucoma?
1) epiphora
2) photophobia
3) blepharospasm
What is the corneal diameter in buphthalmos?
> 12 mm
What is the normal infant IOP under general anesthesia?
10 - 15 mmHg
What are causes of reduced visual acuity in infantile glaucoma?
corneal edema, optic atrophy, myopia, astigmatism, lens dislocation, retinal detachment
Is cupping more or less reversible in children than adults?
More reversible
What is the preferred therapy for PCG?
goniotomy or trabeculotomy
What two drug classes can be used as temporizing measures in a patient with PCG?
1) beta blockers
2) CAIs
What percent of cases of Axenfeld-Rieger syndrome are associated with glaucoma?
50%
What is posterior embryotoxon?
A prominent and ANTERIORLY displaced Schwalbe line (termination of Descemet membrane)
What percent of patients with aniridia develop glaucoma?
50% - 75%
What is the presumed cause of glaucoma in Sturge-Weber syndrome?
increase episcleral venous pressure (EVP)
Is NF-2 associated with glaucoma?
No
What is the mechanism of beta blockers in reducing IOP?
inhibition of cAMP production in ciliary epithelium, thereby reducing aqueous production by 20 - 50% and reducing IOP by 20-30%
How long after discontinuation are beta blockers still present?
4 weeks
What is the usual dosing of beta blockers?
BID
Can beta blockers lose efficacy?
Yes, through long-term drift, tachyphylaxis, and short-term escape
is betaxolol a selective or non-selective beta antagonist?
Beta-1 selective antagonist – safer for patients with pulmonary issues
What are the two classes of miotics used in the treatment of glaucoma?
1) cholinergic agonists
2) anticholinesterase agents
Is myopia induced by cholinergic agents?
Yes, through ciliary muscle contraction
Are anticholinesterase agents cataractogenic?
Yes
What percent of ciliary epithelial carbonic anhydrase activity must be abolished to decrease aqueous production?
over 90%
Which systemic CAI has a longer duration of action – methazolamide or acetazolamide?
methazolamide
Should patients with sulfa allergies avoid CAIs?
in most cases, since CAIs are derived from sulfa drugs and may cause similar allergic reactions and cross-reactivity
What renal complications of CAIs exist?
metabolic acidosis, increased formation of calcium oxalate and calcium phosphate renal stones
If a CAI is used in conjunction with a thiazide diuretic, which electrolyte should be monitored?
K, hypokalemia can result
What are common adverse effects of topical CAIs?
1) bitter taste
2) blurred vision
3) punctate keratopathy
What is the mechanism of action of the non-selective adrenergic agonists?
increase in both trabecular and uveoscleral outflow
What are common side effects of epinephrine and dipvefrin?
1) adrenochrome deposits in multiple tissues
2) CME
3) angle closure
Which of the alpha-2 agonists apraclonidine and brimonidine is more selective than the other?
brimonidine is more selective for alpha-2
What is the mechanism of action of the selective alpha-2 agonists?
1) decrease aq production
2) decrease EVP
3) improve trabecular outflow
Should brimonidine be avoided in children?
Yes, due to risk of somnolence, hypotension, seizures, apnea
What is the mechanism of action of the prostaglandin analogs latanoprost and travoprost?
increasing uveoscleral outflow
What is the mechanism of action of the prostaglandin analog bimatoprost?
increasing uveoscleral outflow AND increasing trabecular outflow
What is the usual dosing of the prostaglandin analogs?
QHS
What occurs in the darkening of the iris and periocular skin with prostaglandin analog use?
Increased number of melanosomes within melanocytes
Are blue irides more or less susceptible to darkening with prostaglandin analogs than other irides?
Less susceptible than others
What two medications does Cosopt contain?
timolol and dorzolamide
What are the two most commonly used hyperosmotic agents?
1) oral glycerin
2) IV mannitol
What is the mechanism of action of the hyperosmotic agents?
Create an osmotic gradient between blood and vitreous, drawing water from vitreous cavity and reducing IOP
Can glycerin produce hyperglycemia?
Yes, it is metabolized to sugar and ketones
Which topical agents are the most effective at lowering IOP long-term?
The prostaglandin analogs
Which agents are commonly used as an initial IOP-lowering agent in open-angle glaucoma?
the prostaglandin analogs
Which is the only pregnancy class B glaucoma medication?
brimonidine
In which two glaucomas is surgical therapy first-line?
1) pupillary block
2) PCG
What is the IOP reduction expected with LT when performed effectively?
20% - 25% reduction
What is one possible mechanism for LT?
shrinking of TM where laser has been applied, causing stretching of adjacent areas
Where is laser applied in ALT?
The junction of the anterior nonpigmented and posterior pigmented edge of the TM
What type of laser is used for SLT?
a frequency-doubled Q-switched Nd:YAG laser
What is the target of the SLT laser?
intracellular melanin
What is the most significant complication of LT?
transient rise in IOP (20% of patients)
Which agents are commonly used to control post-LT transient IOP elevation?
apraclonidine or brimonidine
What is the 10-year success rate of LT?
30%
Should a blind eye be considered for incisional glaucoma surgery?
No, ciliary body ablation should be considered instead
What are potential causes for loss of central visual acuity after incisional glaucoma surgery?
1) cataract
2) hypotony
3) CME
4) blebitis/endophthalmitis
Use of antifibrotic agents during trabeculectomy increases the risk of what?
hypotony (particularly in young patients with myopia)
What is the usual duration of application of mitomycin C when used in trabeculectomy?
1 to 5 minutes
What are the potential early complications of glaucoma filtration surgery?
1) wound leakage/hypotony
2) shallow AC
3) serous or hemorrhagic ciliochoroidal effusions
What is one contraindication to laser iridectomy/iridotomy?
rubeosis iridis
Where is it easiest to penetrate the cornea with an iridotomy?
In an iris crypt
What are 5 potential complications of laser iridectomy/iridotomy?
1) focal lens or corneal damage
2) retinal detachment
3) bleeding
4) visual symptoms
5) IOP spike
Which glaucoma tube shunts have valves?
Ahmed and Krupin
Which glaucoma tube shunts do not have valves?
Baerveldt and Molteno
What is the orientation of a glaucoma tube shunt?
The tube is placed in the AC or through the pars plana and flows to an external reservoir, which is placed in the equatorial region on the sclera
What are five situations in which a tube shunt may be indicated?
1) trabeculectomy failure (with or without antifibrotics)
2) active uveitis
3) neovascular glaucoma
4) inadequate conjunctiva
5) aphakia
What is a relative contraindication to tube shunt surgery?
borderline corneal endothelial function
What is a contraindication to cyclodestructive procedures?
Good vision, due to the risk of loss of visual acuity
What are 3 methods for performing cyclodestructive procedures?
1) transscleral Nd:YAG
2) transscleral diode laser
3) endoscopic laser
Should the eye be dilated when performing a goniotomy or trabeculotomy for a child with PCG?
No, avoiding dilation will better protect the lens during the procedure
What does trabeculotomy involve?
Insertion of a fine wire-like instrument (trabeculotome) into Schlemm canal from an external incision and tearing of the TM by rotating the trabeculotome into the anterior chamber.
