Glaucoma Flashcards
(254 cards)
1
Q
How many axons are present in a typical opic?
A
1 to 1.2 million axons.
2
Q
What is the best method for examining for the opitc nerve?
A
A slit lamp examination with a posterior pole lens gives the best magnification and stereoscopic view.
3
Q
Name the two cell types found within the ganglion cell layer?
A
M cells (magnocellular) have large diameter axons, synapse in the magnocellular layer of the lateral geniculate body, and are sensitive to changes in dim illumination. P cells (parvocellular) comprise the majority of the ganglion cells, have small diameter axons, synapse in the parvocellular layers of the lateral geniculate body, and are used in color and fine detail.
4
Q
Name the four layers of the optic nerve and their respective vascular supply.
A
Nerve fiber layer- Central retinal artery. Prelaminar layer- short posterior ciliary arteries. Laminar layer- short posterior ciliary arteries. Retrolaminar layer- branches of the meningeal arteries and central retinal artery.
5
Q
How do the short posterior ciliary arteries in the optic nerve differ from those of the choriocapillaris?
A
The short posterior ciliary arteries in the optic nerve resemble retinal capillaries. They are surrounded by pericytes, have tight junctions, and lack fenestrations.
6
Q
Why does glaucomatous cupping occur earlier in children than in adults?
A
The scleral ring surrounding the optic nerve expands with increased IOP in children and infants.
7
Q
What supplies essential nutrients and removes waste from the lens, cornea, and trabecular meshwork.
A
The aqueous humor acts as a substitute blood for these avascular tissues.
8
Q
What percentage of plasma proteins is filtered out by the blood-aqueous barrier in the formation of aqueous humor?
A
More than 99% of plasma proteins are absent from aqueous. Normal aqueous has a protein content of about 0.02g/100ml, while plasma contains about 7g/100ml.
9
Q
How far away is the optic nerve head from fixation in the visual field?
A
10-15°
10
Q
What retinal layer is most damaged by glaucoma?
A
Nerve fiber layer.
11
Q
Patient’s with which type of glaucoma are most likely to have splinter hemorrhages of the optic disc?
A
Normal-tension glaucoma
12
Q
What photographic technique best demonstrates early nerve fiber layer thinning?
A
High contrast black-and-white photography.
13
Q
What is the initial medical management for ciliary-block (malignant) glaucoma?
A
Atropine and corticosteroids as well as aqueous suppressants to control IOP as needed.
14
Q
How does the Schiotz tonometer work?
A
The IOP is determined by measuring the indention of the cornea by a known weight on a linear scale on the instrument. The value is then converted using a table to IOP in mmHg.
15
Q
When should digital palpation be used to measure IOP and how accurate is it?
A
IOP estimation by digital palpation should be reserved fro uncooperative patients only, because its only useful in detecting large differences in IOP between two eyes.
16
Q
Why is it important to clean tonometers between uses?
A
Many viruses, including those causing AIDS, EKC, and hepatitis, can be recovered from the tears of infected individuals.
17
Q
What type of inheritance pattern is seen in juvenile-onset glaucoma?
A
Juvenile-onset glaucoma has been shown to follow an autosomal dominant inheritance pattern by large pedigree studies, and a genetic marker has been identified on chromosome 1q.
18
Q
What is the first assessment that should be made when evaluating an automated visual field?
A
Noting the percentage of fixation losses, false positives, false negatives, and fluctuations should first assess the quality of the test.
19
Q
What is the average fluctuation seen between points on an automated visual field in normal and abnormal subjects?
A
The average fluctuation should be less than 2 dB in a normal field, less than 3 dB in cases of early damage, and less than 4 dB in cases of moderate damage.
20
Q
How is adult-onset primary open angle glaucoma thought to be inherited?
A
It most closely follows an autosomal recessive pattern.
21
Q
What is Sampaolesi’s line
A
Pigment deposited anterior to Schwaldbe’s line, which is seen in pseudoexfoliation syndrome and pigmentary dispersion syndrome.
22
Q
What type of artifact will be produced if a patient quits responding midway through a Humphrey visual field test?
A
A cloverleaf-shaped field is a common artifact seen in automated visual field testing.
23
Q
What effect is seen if a patient’s spectacle correction is not used during automated perimetry?
A
Generalized depression of visual sensitivity.
24
Q
What effect does a media opacity, such as cataract, have on the results of automated perimetry?
A
Media opacities cause a generalized depression of the visual field with a normal pattern standard deviation. Miotic pupils can cause similar artifacts.
25
The goal of serial visual field testing is to detect progression of glaucomatous damage. What is mandatory for this type of interpretation?
An accurate baseline field.
26
What is the mechanism of action for the antimetabolites 5-fluorouracil and mitomycin C to increase the success rate of glaucoma filtering surgery?
Both of these medications inhibit the proliferation of fibroblasts and mitomycin C also affects the proliferation of vascular endothelial cells. 5-FU is a fluorinated pyrimidine inhibitor of thymidylate synthase and is an S-phase specific agent. Mitomycin C is a cell cycle nonspecific alkylating agent.
27
A diurnal fluctuation of greater than 10 mmHg suggests what diagnosis?
Glaucoma.
28
What antioxidant is found at levels 10 to 50 times higher in aqueous than plasma?
Ascorbic acid (Vitamin C)
29
What enzyme found in the aqueous provides essential antibacterial activity?
Lysozyme.
30
Low-tension glaucoma patients have been divided into what two groups by some authorities. What are they?
1. The senile sclerotic group has a characteristic shallow, pale sloping of the optic nerve rim. 2. The focal ischemic group suffers deep, focal notching in the optic nerve rim.
31
How do the typical visual field defects of low-tension glaucoma patients differ from those of high-tension glaucoma patients?
They are usually more dense, focal, and closer to fixation.
32
Does low-tension glaucoma seem to have any race predilection?
Yes, it seems to have a higher prevalence among Japanese patients.
33
What test should be used clinically to rule out POAG before making a diagnosis of low-tension glaucoma?
Diurnal IOP measurement.
34
What in a patient's medical history could explain the optic neuropathy and visual field loss that would otherwise be labeled normal-tension glaucoma?
History of hemorrhagic shock, myocardial infarction, anemia, syphilis, or vasculitis.
35
What growth modulatory factor shows increased levels in the aqueous when any ocular neovascularization is present?
Vascular endothelial growth factor (VEGF)
36
How do you perform the dark room prone test?
This test is done in patients with suspiciously narrow angles. IOP is first measured, and then the patient is seated for 30-60 minutes in a darkened room with the head down on a cushioned table. The IOP is again measured in the darkened room. A rise of 6-8 mm Hg or greater or a significant asymmetric rise in IOP accompanied by gonioscopic confirmation of furter angle closure is a positive test, and a laser iridotomy is performed. Placing the patient in a brightly-lit room for 5 minutes after this test and observing a significant lowering of IOP is further confirmation of a positive test.
37
Why do some glaucoma experts advocate the use of calcium channel blockers in low-tension glaucoma patients?
Calcium channel blockers may increase perfusion to the optic nerve.
38
What oral osmotic agent should be used to lower the IOP of a diabetic patient with an attack of acute angle closure glaucoma?
Isosorbide.
39
What neurological complication can result from use of osmotic agents such as mannitol and urea?
Brain shrinkage with traction on vessels and subsequent subarachnoid hemorrhage.
40
Which part of the ciliary body is responsible for active secretion of aqueous?
Nonpigmented ciliary epithelium.
41
What are the partial pressures of oxygen and carbon dioxide in the aqueous?
Oxygen: 55 mm Hg. Carbon dioxide: 40-60 mm Hg.
42
What is the normal pH of aqueous humor?
Normal range is 7.5-7.6.
43
What is the most prevalent type of adrenergic receptors in the ciliary epithelium?
Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.Beta2 receptors.
44
A patient presents for exam one day following a trabeculectomy. She is comfortable, the anterior chamber is shallow and the IOP is 2. The bleb is flat and no choroidals are present. What test will make the diagnosis apparent?
Seidel testing. This patient has the classic findings of a wound leak with a low IOP, shallow AC and a flattened filtering bleb.
45
What does the fibrillar material deposited in the anterior chamber of the eye in pseudoexfoliation syndrome resembles histochemically?
Amyloid.
46
Which is the only form of primary angle closure glaucoma that is not totally caused by a pupillary block mechanism?
Plateau iris.
47
Is there a difference in the success rate between limbus-based and fornix-based conjunctival flags?
No. A fornix-based flap is easier to dissect and close but there is an increased risk of leakage at the limbus, especially with the use of adjunctive antimetabolites.
48
What method is most commonly used to measure the rate of aqueous formation?
Fluorophotometry
49
What is the mean IOP of the population in general?
The mean IOP is approximately 16 mmHg and there is a standard deviation of 3 mmHg. The distribution is skewed toward the higher values, and this is more apparent in people over 40.
50
Why does the pattern of deposits on the anterior lens capsule in pseudoexfoliation syndrome resembles a target?
The iris rubs off the material during normal pupillary size changes, leaving a clear zone between areas of central and peripheral deposition.
51
Why is a relatively shallow anterior chamber a common finding in patients with pseudoexfoliation syndrome?
Forward movement of the lens-irs diaphragm sometimes occurs secondary to the zonular weakness tah accompanies the disorder.
52
What is the mechanism of action of latanoprost?
Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.Latanoprost is a prostaglandin Fαodrug, which lowers IOP by increasing uveoscleral outflow of aqueous.
53
Acutely, how would the IOP change with a 4 mmHg rise in episcleral venous pressure?
The IOP would also rise 4 mmHg. There is a 1:1 change in IOP with acute changes in episcleral venous pressure. This does not hold true for chronic conditions.
54
What is the approximate turnover time of aqueous humor?
About 1% of the aqueous is replaced every minute, so turnover time is approximately 100 minutes.
55
What happens to outflow facility as a person ages?
Outflow facility decreases as age increases.
56
What are two complications of cataract surgery seen frequently in patients with pseudoexfoliation syndrome?
Zonular dehiscence and vitreous loss.
57
What region of the world has the highest prevalence of pseudoexfoliation syndrome?
Pseudoexfoliation syndrome is responsible for up to 50% of open-angle glaucoma in Scandinavian countries.
58
When may releasable sutures be removed from a trabeculectomy?
Releasable sutures usually are pulled at any time between 1 and 21 days. This time may be extended with the use of adjunctive antimetabolite therapy and an effect may be seen up to one year postoperatively according to some reports.
59
What causes the iris transillumination defects seen in pigment dispersion syndrome?
It is thought that zonular contact with the iris pigment epithelium is responsible for the release of pigment.
60
What type of drug is brimonidine?
It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.It is selective alpha2 adrenergic agonist.
61
How does alcohol use affect IOP?
Consumption of alcohol decreases IOP for a short time.
62
How does the risk of developing glaucoma change over time in an eye with angle recession?
The risk of developing glaucoma drops off substantially after a few years.
63
What is the treatment of choice for angle recession glaucoma?
Aqueous suppressants.
64
How many times more common is glaucoma among blacks as compared to whites?
The prevalence of glaucoma is 3 to 6 times higher in blacks than in whites.
65
In what way is glaucoma associated with cyclodialysis clefts?
An abrupt increase in IOP may occur as the cleft closes. When a cleft is open, hypotony is more likely because of increased uveoscleral outflow.
66
What type of eyes is associated with anatomically narrow angles?
Small, hyperopic eyes, e.g. nanophthalmos.
67
Why has some experts advocated laser peripheral iridotomy (LPI) for patients with pigmentary glaucoma?
To relieve the posterior bowing commonly seen in the peripheral iris of these patients and subsequently decrease contact between the iris pigment epithelium and zonules, LPI has been advocated by some, but its efficacy has not yet been established.
68
What physiologic mechanisms are responsible for aqueous humor production, and which mechanism produces most of the aqueous?
Diffusion, ultrafiltration, and active secretion produce aqueous. It is widely believed that most of the aqueous is produced by active secretion, which involvesa Na-K ATPase active transport pump.
69
Compare the concentrations of sodium, potassium, magnesium, calcium, and lactate in plasma and aqueous?
The concentration of sodium, potassium, and magnesium in aqueous is similar to plasma, while calcium is about half that found in plasma. Lactate concentrations in aqueous is higher than in plasma.
70
What happens to IOP as a patient lies down?
IOP is usually higher when lying down as compared to sitting upright.
71
How does phacolytic glaucoma occur?
It occurs when denatured lens proteins from a hypermature cataract leak through an intact lens capsule, causing an inflammatory reaction in the anterior chamber. Macrophages engorged with lens proteins, fill the anterior chamber and clog the trabecular meshwork, causing a rise in intraocular pressure.
72
What effect does cannabis have on IOP?
Cannabis use decreases IOP, although it has no established clinical use in this regard.
73
Does caffeine affect IOP?
Yes, caffeine sometimes causes a transient rise in IOP.
74
What is the difference between choroidal detachments and retinal detachments with regards to their anterior extent on B-scan ultrasonography?
Choroidal detachments can extend to the scleral spur, while retinal detachements end at the ora serrata.
75
What types of glaucoma are nanophthalmic eyes prone to?
Angle closure glaucoma.
76
What group of patients is at increased risk for developing glaucoma following a hyphema?
Patients with any of the sickle cell hemoglobinopathies are at increased risk because sickled red blood cells are more likely to clog the trabecular meshwork.
77
What medication should be avoided in sickle cell patients with a hyphema?
Carbonic anhydrase inhibitors are thought to increase sickling in the anterior chamber.
78
Name two conditions that can produce elevated episcleral venous pressure and dilated episcleral vessels.
Sturge-Weber syndrome and arteriovenous fistulas.
79
An infant with congenital glaucoma has cloudy corneas. What is the surgical treatment of choice?
Trabeculotomy, since this does not require a clear cornea to be performed.
80
What position must the patient be in when you perform Koeppe gonioscopy?
The patient must be supine.
81
When is Koeppe gonioscopy most commonly used?
During examination under anesthesia and when performing goniotomy.
82
What are the lenses changes following an attack of angle closure glaucoma called?
Glaukomflecken
83
What is the explanation for the increased risk of choroidal and exudative detachments when performing surgery on nanophthalmic eyes?
Nanophthalmic eyes are small with thick sclera, which impedes vortex vein drainage.
84
Describe the normal diurnal variation of IOP.
Over a 24-hour period, IOP varies 2-6 mmHg in the normal population.
85
What is the difference between a cyclodialysis and an angle recession?
A cyclodialysis is a separation of the ciliary body from the scleral spur, while an angle recession is a separation of the longitudinal and circular muscles of the ciliary body.
86
Two weeks after filtering surgery, a glaucoma patient presents with an IOP of 40 mmHg, a low lying bleb and a deep anterior chamber. What is the cause for the high pressure in this patient?
Gonioscopy will probably show blockage of the sclerostomy. YAG laser therapy may reopen it.
87
Which miotic agent has both indirect and direct cholinergic activity?
Carbachol, which is an acetylcholine analog and a competitive inhibitor for acetylcholinesterase.
88
What are the major risk factors for spikes in intraocular pressure after argon laser trabeculoplasty?
Posterior laser burns, dense trabecular pigment, and poor outflow facility.
89
What phacomatoses are associated with congenital glaucoma?
Sturge-Weber syndrome and neurofibromatosis type I (NF-1).
90
What angle structure is the peripheral termination of Descemet's membrane?
Schwalbe's line
91
What portion of the trabecular meshwork is adjacent to Schlemm's canal?
The trabecular meshwork has three portions: uveal, corneoscleral, and juxtacanalicular. The juxtacanalicular meshwork lies adjacent to Schlemm's canal.
92
A diabetic patient presents with acutely elevated IOP following a vitreous hemorrhage. She appears to have a small hypopyon. What is the name for this secondary glaucoma and what is the pseudohypopyon composed of?
Ghost cell glaucoma may present with a pseudohypopyon that is actually composed of degenerated red blood cells or erythroclast. These decomposing cells can mechanically block aqueous outflow.
93
What is the most likely cause for a shallow anterior chamber with a low intraocular pressure and a flat bleb in the immediate postoperative period following a trabeculectomy for primary open angle glaucoma?
Bleb leak
94
What is the main advantage of using dipivefrin over topical epinephrine?
Dipivefrin is a prodrug of epinephrine that must first enter the cornea to be activated by esterases within the stroma; hence systemic side effects are reduced.
95
Name three techniques that the patient can do to improve the absorption of ocular medications.
1. Digital nasolacrimal compression. 2. Close the eye for 5 minutes after instillation of drops. 3. Wait 10 minutes in between the administration of different drops.
96
How can systemic sulfonamides produce glaucoma?
Systemic sulfonamides can cause idiosyncratic choroidal detachments and precipitate angle closure glaucoma.
97
Is a posterior embryotoxon typically associated with primary infantile glaucoma?
A prominent, anteriorly displaced Schwalbe's line or posterior embryotoxon can be seen in Axenfeld-Rieger syndrome but is not typically seen in primary infantile glaucoma.
98
What is the most common reason for long-term visual loss in primary infantile glaucoma?
Amblyopia.
99
A glaucoma patient taking betaxolol, pilocarpine, acetazolamide, and dipivefrin is scheduled to undergo cataract surgery. Which of his medications should be discontinued temporarily?
Pilocarpine and adrenergic agonists such as dipivefrin can weaken the blood-aqueous barrier and worsen inflammation. They should therefore be discontinued prior to surgery if possible.
100
A patient with open angle glaucoma is started on carteolol eye drops to his right eye. What can you expect to see occur in the left eye after two weeks of therapy?
There will often be a reduction of intraocular pressure in the contralateral eye with unilateral use of a topical beta-blockers, although less than in the treated eye.
101
What are the main sources of blood supply to the anterior optic nerve?
Posterior ciliary arteries via the peripapillary choroid or the short posterior ciliary arteries.
102
What are the most common causative organisms in a late bleb-associated endophthalmitis?
H. influenzae and S. pneumoniae.
103
What risks factors can be associated with chronic primary angle-closure glaucoma?
Hyperopia, cataract progression, advancing age, pseudoexfoliation syndrome
104
How many optic nerve axons must be lost before kinetic perimetry will show a visual field defect?
50% of the axons in the optic nerve
105
Why should gonioscopy be performed in patients with narrow angles and chronic angle-closure glaucoma after starting miotic therapy?
Miotic therapy can increase the realtive pupillary block by allowing forward movement of the lens against a constricted pupil, thereby exacerbating chronic angle-closure and precipitating an acute attack of angle-closure glaucoma. Gonioscopy must be performed in these patients to determine if worsening angle closure is occuring.
106
What are Haab's striae?
They are breaks in Descemet's membrane in eyes with enlarged corneas resultig from congenital glaucoma. Irregular astigmatism is often present.
107
Two days after a trabeculectomy, a 72 year-old patient presents with an IOP of 45 mm Hg, shallow anterior chamber, patient iridectomy and no choroidal detachment on B-scan. How would you manage this patient, and is miotic therapy indicated?
This patient has malignant glaucoma and should be started on beta-blockers, carbonic anhydrase inhibitors to reduce the IOP and topical cycloplegic therapy to relieve the pupillary block by tightening the zonules and posteriorly displacing the lens. Miotic therapy will exacerbate the block and increase inflammation. Vitrectomy is indicated if medical therapy is not successful.
108
In what types of patients are peripupillary iris transillumination defects and radial peripheral iris transillumination iris defects more commonly found in?
Peripupillary iris transillumination defects may be present in pseudoexfoliation syndrome, while radial peripheral iris transillumination defects are more commonly found in pigmentary dispersion syndrome.
109
A 45-year-old Filipino patient presents with an acute attack of angle closure glaucoma despite having patent laser iridotomies done previously. This slit lamp examination shows the anterior chamber to be deep centrally and the iris plane to be flat. What is the most likely diagnosis?
Plateau iris syndrome.
110
What procedure is indicated in a patient with plateau iris syndrome in which the angle remains appositionally closed or occludable after laser iridotomy?
Laser peripheral iridoplasty. The anterior positioning of the ciliary processes causes the iris root to remain in contact with the angle structures.
111
Identification of gonioscopic landmarks is simplest in which portion of the angle?
The inferior angle is usually wider and more pigmented.
112
Describe the gonioscopic findings seen in angle closure.
The trabecular meshwork is not visible because the peripheral iris obstruct it.
113
Describe the gonioscopic findings in plateau iris configuration.
The peripheral anterior chamber apears closed with a flat iris plane while the central anterior chamber is deep, resulting from an anterior position of the ciliary processes and an abnormal configuration of the iris.
114
What does pressure on a Goldmann indirect gonioscopy lens does to angle? What about a Zeiss lens?
The angle is falsely narrowed when pressure is applied to a Goldmann lens. Pressure applied to a Zeiss lens will falsely open the angle.
115
How can pressure applied to the central cornea with a Zeiss lens (indentation gonioscopy) is used clinically?
This technique can be used to distinguish peripheral anterior synechia (PAS) from iridocorneal touch.
116
What visual field abnormality would most likely be seen in a patient with a progressive nuclear sclerotic cataract in the absence of other abnormalities?
Progressive nuclear sclerotic cataracts are more likely to cause a generalized depression of the central visual field and an even depression of thresholds rather than focal defects or scotomas. The pattern standard deviation will probably remain the same.
117
What type of glaucoma medication is apraclonidine?
It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.It is an alpha2-adrenergic agonist.
118
What is the pathogenesis of angle closure glaucoma secondary to neovascularization of the iris?
Contraction of myofibroblasts that accompany the new vessels lead to PAS and closure of the angle.
119
During gonioscopy you note a prominent scleral spur, abnormally wide ciliary body band, and torn iris processes in the temporal angle of a patient's right eye. What are your diagnosis and what history should you try to obtain from the patient?
Angle recession is the diagnosis and you should ask about a history of trauma to the right eye.
120
What is the desired tissue response of an argon laser trabeculoplasty?
Blanching of the trabecular meshwork. Minimal bubble formation may also be noted with correct laser treatment.
121
In patients with increased pigmentation of the trabecular meshwork, should the power be increased or decreased?
Decreased. As pigmentation increases, the current of laser energy absorbed increases. Laser power setting may require adjustment as pigmentation varies in differing quadrants.
122
What effect does thymoxamine have on the pupil and outflow facility?
Thymoxamine causes miosis but has no effect on outflow facility.
123
What are some causes of a depressed ring of peripheral points in a central 30° visual field program?
Lens rim artifact, ptosis, and retinal disorders, eg. Chorioretinal scars, retinitis pigmentosa.
124
What term is used to describe low pressure after filtration surgery associated with choroidal folds decreased visual acuity and retinal pigment epithelial changes?
Hypotony maculopathy
125
What does the pattern standard deviation in an automated perimetry signify?
It highlights localized visual field defects rather than diffuse generalized visual field depression.
126
Filtering blebs in the inferior quadrants or in the intercanthal region increase the risk of what serious complication?
Endophthalmitis.
127
What finding on slit lamp examination is important to differentiate a bleb infection from endophthalmitis?
Cells in the vitreous cavity indicating involvement of the posterior segment.
128
What optic nerve findings will be suggestive of glaucomatous optic nerve damage in a patient with elevated intraocular pressure?
1. Cup-to-disc ration asymmetry greater than 0.2. 2. Notch formation in the optic nerve rim, even in patients with 0.4 cups.
129
What is the mechanism for angle closure glaucoma following extensive panretinal photocoagulation?
Swelling and anterior rotation of the ciliary body, which does not respond to laser iridectomy.
130
What procedure should be considered in patients at risk for development of intraoperative and postoperative choroidal hemorrhage (e.g. Sturge-Weber syndrome)?
Prophylactic sclerotomies.
131
How do carbonic anhydrase inhibitors lower intraocular pressure?
They suppress aqueous humor production by an indirect inhibition of sodium transport in the nonpigmented ciliar y epithelium.
132
Do people taking carbonic anhydrase inhibitors develop a metabolic alkalosis or acidosis? Why?
Carbonic anhydrase inhibitors can produce a metabolic acidosis because of alkaline diuresis and loss of sodium, potassium, and bicarbonate in the kidneys.
133
What serious side effect can occur with carbonic anhydrase inhibitors when prescribed to people already taking glucocorticosteroids, thiazide diuretics, or digitalis?
Hypokalemia-induced cardiac arrhythmias.
134
What are the risk factors for failure of goniotomy?
Glaucoma diagnosised at birth, other ocular abnormalities, corneal diameter > 14mm or age > 2 years.
135
What are the most serious hematologic side effects of carbonic anhydrase inhibitors?
Thrombocytopenia and aplastic anemia, which is idiosyncratic.
136
What is the most common reason for discontinuation of a Simmons shell used to tamponade a bleb leak?
Patient discomfort.
137
What is the most serious complication of laser peripheral iridotomy?
Elevation of IOP. Treatment with topical apraclonidine significantly decreases both the frequency and magnitude of the rise in IOP. IOP should always be measured 1-2 hours after the procedure.
138
What is the treatment for patients with angle closure glaucoma following panretinal photocoagulation for diabetic retinopathy?
Topical cycloplegics and corticosteroid therapy may cause posterior rotation of the ciliary body and open the angle. Laser iridoplasty is performed if the angle closure fails to respond to medical therapy.
139
An elderly patient develops sudden, severe eye pain 36 hous after filtering surgery while going to the restroom. What diagnosis is most likely?
Suprachoroidal hemorrhage.
140
What procedure must be performed to distinguish pupillary block from plateau iris configuration?
Peripheral iridotomy or iridectomy.
141
Can topical betaxolol (Betoptic) be safely used in a patient with congestive heart failure?
No. Both nonselective and beta-1-selective beta-blockers, such as betaxolol, can worsen congestive heart failure.
142
What beta-blockers can be combined with dipivefrin to produce a greater additive effect than dipivefrin alone?
A greater additive effect of dipivefrin with betaxolol can be seen over dipiverfrin with nonselective beta-blockers, such as timolol and levobunolol.
143
What side effects are epinephrine and possibly dipivefrin associated with in aphakic eyes?
Cystoid macular edema.
144
In what conditions is blood in Schlemm's canal commonly seen?
Hypotony, Sturge-Weber syndrome, carotid-cavernous sinus fistulas.
145
What transient side effect can apraclonidine produce in eyelids?
Transient lid retraction.
146
With regards to corticosteriod reponsiveness, what percentage of offspring of POAG patients are high responders?
25%
147
What percentage of the general population are steroid high responders?
5%
148
What percentage of patients with established POAG are steroid high responders?
90%
149
Would laser iridotomy be useful in treating a patient with elevated IOP and ICE syndrome?
No. The mechanism of glaucoma in eyes with ICE syndrome is through angle closure, but there is no pupillary block present.
150
What is the most likely cause for severe blurring of vision in a young, highly myopic patient following a single application of pilocarpine?
Increased myopia.
151
Can miotics be used in a glaucoma patient who has aniridia and open angles?
Yes. The effect of miotic agents is mediated through the ciliary muscle and not the pupillary sphincter.
152
What conditions can produce glaucomatous visual field-like defects?
Optic nerve drusen, retinal vascular occlusive disease and ischemic optic neuropathy.
153
Can cataract extraction resolve or prevent glaucoma in a patient with pseudoexfoliation syndrome?
No. The pseudoexfoliative material will continue to be produced by nonpigmented ciliary epithelium and other ocular tissues. This can be found on the anterior chamber angle, iris, corneal endothelium, and lens capsule in pseudophakic and aphakic eye.
154
What is the difference between Rieger's anomaly and Rieger's syndrome?
Both conditions have posterior embryotoxon and iris anomalies (corectopia, stromal hypoplasia, pseudopolycoria, and ectropion uveae). When dental anomalies (hypodontia and microdontia) and facial anomalies (maxillary hypoplasia, telecanthus, hypertelorism, broad nasal bridge) are present, the condition is called Rieger's syndrome.
155
What is a posterior embryotoxon?
Anteriorly displaced Schwalbe's line.
156
If a patient has a posterior embryotoxon and no other abnormality, what is this condition called?
Axenfeld's anomaly.
157
What is the inheritance pattern of Rieger's anomaly?
Autosomal dominant.
158
How often does glaucoma develop in eyes with Rieger's anomaly?
50%, usually during childhood or early adulthood.
159
A patient reports worsening ptosis and diplopia with use of topical beta-blockers. What is the most likely explanation for this?
The patient may have myasthenia gravis, which can be exacerbated by topical beta-blockers.
160
What are the main causes of a shallow anterior chamber following filtering surgery?
1. Wound leak. 2. Excessive filtration. 3. Pupillary block. 4. Malignant glaucoma.
161
What complications can result from excising the block too far posterior during a trabeculectomy?
Excising the block too posteriorly can result in vitreous loss and an inadvertent cyclodialysis cleft. Hemorrhage can also occur if the major arterial circle to the iris is cut.
162
What type of anirdia is associated with neuroblastoma or Wilm's tumor?
Sporadic, nonfamilial aniridia.
163
Is the episcleral venous pressure increased or decreased in Sturge-Webber syndrome?
Increased.
164
What is the normal rate of aqueous flow?
2 to 3 μl/min.
165
What type of medication is dapiprazole and what is it used for?
It is an alpha-adrenergic antagonist used to reverse sympathomimetic-induced pupillary dilation.
166
A patient has bilaterally narrow angles and IOPs of 28 mmHg OU. The IOP does not decrease after thymoxamine administration. What does this indicate, and how will it affect your management?
Patients with mixed mechanism glaucoma have open angle glaucoma with partial angle closure secondary to pupillary block. Thymoxamine, an alpha-adrenergic antagonist, causes miosis and lessens pupillary block without affecting outflow facility and is useful in determining whether partial angle closure due to pupillary block is present. In this case where thymoxamine-induced miosis fails to lower IOP, partial angle closure is not present, and iridotomy may not be helpful in lowering IOP.
167
A glaucoma patient taking echothiophate drops requires abdominal surgery. What complication should the anesthesiologist be alert for in this patient if general anesthesia is used?
Echothiophate decreases serum pseudocholinesterase activity and accentuates the effect of succinylcholine, resulting in prolonged respiratory paralysis after general anesthesia.
168
An 80-year-old patient presents with normal intraocular pressures, rubeosis iridis with synechial angle closure, midperipheral retinal hemorrhages and poor vision in his left eye. What is the most likely diagnosis?
Ocular ischemic syndrome.
169
Where is the angle is resistance to aqueous outflow greatest?
Juxtacanalicular meshwork.
170
A 60-year-old patient presents to your clinic with headache, right eye pain, and redness. She has a history of sudden loss of vision in her right eye 4 months ago. The IOP in her affected eye is 42 mmHg. The gonioscopic examination reveals angle neovascularization. What is the procedure of choice for treating this patient?
Panretinal photocoagulation
171
What are the four mechanisms by which uveal melanomas can produce glaucoma?
1. Direct invasion of the anterior chamber angle by tumor. 2. Angle closure from forward displacement of the lens-iris diaphragm. 3. Clogging of the trabecular meshwork with pigment or macrophages filled with pigment from necrotic tumor. 4. Iris neovascularization.
172
Which parts of the optic disk neuroretinal rim is most affected early in normal tension glaucoma?
Temporal and inferotemporal neuroretinal rim.
173
When does epithelial downgrowth occur?
It occurs when the ocular surface epithelium enters the eye through a surgical or traumatic wound and forms a sheet of nonkeratinizing squamous epithelium that grows over the anterior chamber angle, iris, and ciliary body.
174
What is the mean value for outflow facility in the normal eye?
0.28 μl/min/mmHg.
175
What is nanophthalmos?
It is a rare disease characterized by a small eye, high hypermetropia, weak but thick scleara, and a tendency to angle closure glaucoma.
176
Why should eye surgery in a nanophthalmic eye bye avoided where possible?
Any surgery, but especially intraocular surgery and even laser trabeculoplasty may be complicated by severe uveal effusion.
177
What is the most common pathophysiologic mechanism behind developmental glaucoma?
Trabeculodysgenesis.
178
How much does aqueous humor production decrease when active transport is inhibited by ouabain?
Aqueous production decreases by 70%, thus 30% is due to ultrafiltration and diffusion.
179
Which part of the autonomic nervous system is important in aqeous humor production?
Both parasympathetic and sympathetic impulses are important in the release of aqueous humor.
180
When is intraocular pressure highest and lowest?
It is highest in the morning and lowest at midnight.
181
In what condition is Sampaolesi's line seen?
Sampaolesi's line, which is a pigment line seen anterior to the trabecular meshwork, is seen in cases of pseudoexfoliation and pigmentary dispersion syndrome.
182
What prodecure is most appropriate for a patient with an attack of angle closure glaucoma and media opacities or a flat chamber which precludes the use of a laser for a peripheral iridotomy?
Surgical peripheral iridectomy.
183
What is Posner-Schlossman syndrome?
It is a unilateral ocular hypertensive cyclitis in a white eye.
184
What procedure must be performed to distinguish pupillary block from cilliary block glaucoma?
Peripheral iridotomy or iridectomy.
185
What are the gonioscopic features of congential glaucoma?
The angle is open with a high insertion of the iris root and a membrane (Barkan's membrane) covering the angle.
186
What are the risk factors for the development of ciliary block (malignant) glaucoma?
Eyes with chronic angle closure glaucoma, peripheral anterior synechiae, and uncontrolled IOP are at increased risk postoperatively.
187
What are glaukomflecken?
Glaukomflecken are anterior, subcapsular lens opacities caused by foci of cortical fiber necrosis.
188
What is the main advantage of applanation tonometry over Shiøtz tonometry?
Scleral rigidity does not affect the readings of applanation tonometry.
189
What principle does applanation tonometry utilize?
Applanation tonometry uses the Imbert-Fick priniciple (P=F/A, were P=pressure inside a sphere, F=force necessary to flatten its surface, and A= area of flattening.
190
At what diameter of corneal flattening does the resistance of the cornea to flattening and the force exerted by the tear menis pulling the tonometer towards the cornea cancel each other out?
3.06 mm.
191
How is IOP measurement with an applanation tonometer affected by corneal edema or scarring?
Corneal edema produces falsely low readings. Corneal scars produce falsely high reading.
192
What happens to the IOP readng if too much or too little fluorescein is used?
Too much fluroscein produces wide mires = falsely high reading. Too little fluroscein produces narrow mires = falsely low reading.
193
What must you do to obtain accurate applanation tonometry readings in a patient with high corneal astigmatism?
Two readings taken 90° apart can be averaged or the red mark on the tonometer head can be rotated to match the patient's negative corneal axis.
194
What is the mechanism of action of cyclodestructive procedures?
These procedures lower pressure by producing necrosis of the secretory cells of the ciliary epithelium and may also damage the vascular supply of the ciliary body.
195
In what conditions are Krukenberg's spindles seen?
Krukenberg spindles are vertically oriented pigment lines in the shape of a spindle on the corneal endothelium and are a sign of pigment dispersion syndrome.
196
What is the most common cause of a flat or shallow chamber after filtration surgery?
Overfiltration.
197
A patient who recently underwent scleral buckling for retinal detachment develops an acute attack of angle closure glaucoma. What is the mechanism of angle closure in this case, and is peripheral iridectomy indicated?
Obstruction of venous outflow by the buckle can produce choroidal effusions that cause anterior rotation of the ciliary body and secondary angle closure. Peripheral iridectomy is ineffective because there is no pupillary block present. The buckle may need to be repositioned if medical treatment of the glaucoma is not effective.
198
What is the cause of the elevated IOP seen in phacolytic glaucoma?
This is believed to be due to obstruction of the trabecular meshwork by high molecular weigh lens protein, although macrophages filled with engulfed lens material can also be seen
199
What techniques can be used to open a miotic pupil for cataract surgery?
Multiple sphincterotomies, sector iridectomy with secondary closure, manual pupil stretching, hooks inserted thru limbal punctures or pupil-expanding rings (such as a Malyugin ring) can be utilized.
200
Approximately when postoperatively do Tenon's cyst tend to form?
Tenon's capsule may form a thick-walled cyst with 3-6 weeks after filtering surgery in 10-15% of eyes. Most cases resolve with aqueous suppressants and do not require surgical revision.
201
What is the incidence of primary open angle glacoma in the general population over 40 years of age?
0.5 to 1%
202
What goniolenses are useful for distinguishing appositional angle closure from synechial angle closure using indentation gonioscopy and why?
Zeiss and Sussman goniolens are better suited for indentation goniscopy than the Goldmann lens because of their smaller diameters.
203
What is the normal range for episcleral venous pressure?
8-12 mmHg.
204
What is the difference between hemolytic glaucoma versus ghost cell glaucoma with regards to the cause of the rise in IOP?
In hemolytic glaucoma, macrophages filled with hemoglobin from fresh hemorrhage clog the trabecular meshwork. In ghost cell glaucoma, which is seen weeks to months later after a vitreous hemorrhage, degenerated red blood cells from the vitreous enter the anterior chamber and obstruct the trabecular meshwork.
205
What is the medical treatment of angle closure glaucoma in a patient with microspherophakia?
Cycloplegics to relieve pupillary block.
206
What is the incidence of POAG among patients with Fuch's dystrophy?
15%
207
How can iris cysts be prevented when treating POAG with strong miotic agents such as phospholine iodine?
Concomitant use of phenylephrine can prevent iris cysts through an unknown mechanism.
208
What are the ocular manifestations of aniridia?
1. External: microcornea, pannus, sclerocornea, epibulbar dermoids, and keratolenticular adhesions. 2. Lenticular: cataract, upward subluxation, and persisent pupillary membrane. 3. Glaucoma (in 50%) 4. Posterior segment: foveal hypoplasia, choroidal coloboma. 5. Congenital nystagmus.
209
In what part of the visual field do paracentral scotomas occur more frequently?
Upper half of the visual field.
210
How much of a reduction in sensitivity in the visual field is produced by loss of half the number of axons?
This leads to a 5 dB reduction in sensitivity.
211
What are the causes of a ring scotoma?
1. Retinitis pigmentosa. 2. Glaucoma (double arcuate scotoma). 3. Refractive scotoma with aphakic glasses.
212
What is the earliest visual field changes in chronic glaucoma?
The earliest change is a generalized constriction of all isopters, which is nonspecific. The earliest clinically significant visual field defect is a paracentral scotoma.
213
What is the treatment for congenital glaucoma?
Goniotomy, trabeculotomy, trabeculectomy
214
A 6-month-old child has an IOP of 18 mmHg when examined under general anesthesia. Does this rule out the diagnosis of congenital glaucoma?
No, because general anesthesia may lower IOP. The appearance of the optic disc, the cornea and the corneal diabmeter are also important in making the diagnosis.
215
How often is aniridia bilateral?
98% of cases.
216
In what condtions is the use of intravenous mannitol to lower IOP contraindicated?
Pulmonary congestion and edema, heart failure, dehydration, and renal disease.
217
What do high false positive and high false negative error values on a Humphery visual field indicate?
A high false positive value suggests a trigger-happy patient, while a high false negative value suggests inattention.
218
What percentage of total aqueous outflow facility does uveoscleral outflow account for?
10-20%
219
A patient who hada complicated cataract surgery has considerable postoperative corneal edema. What tonometers are useful for measuring IOP in this case?
Pneumotonometer and MacKay-Marg tonometer both applanate a very small area of the cornea and are useful in the presence of corneal edema or corneal scars.
220
How well does pseudoexfoliation glaucoma respond to treatment?
Patients with pseudoexfoliation glaucoma are often resistant to medical therapy but are very responsive to laser trabeculoplasty.
221
A patient with very narrow angles receives dialating eye drops to his eye. If this patient develops an attack of primary angle closure glaucoma, when is this most likely to occur?
It generally takes place after full dilation as the pupil constricts to midposition and maximal iris-lens contact occurs.
222
How do you break an attack of acute angle closure glaucoma?
The IOP should first be lowered using topical beta-blockers, carbonic anhydrase inhibitors, and/or hyperosmotic agents. The iris may not respond to miotics if the IOP is very elevated. Once the IOP is controlled, a laser iridotomy is performed. The other eye should be treated with a prophylactic laser iridotomy. If laser iridotomy cannot be performed, a surgical iridectomy is indicated.
223
How is the prone-dark provocative test performed?
The IOP is measured before and after 30 minutes to an hour with the patient lying prone in a totally dark room. Lying prone will move the lens forward, and the dark will dilate the pupils, thereby increasing pupillary block and causing angle closure in susceptible patients.
224
What are the most popular flow-restricted or nonrestricted tube shunt devices?
Molteno and Baerveldt tube shunt designs.
225
What is the mechanism of action of acute angle closure glaucoma following a recent CRVO?
Transudation of serum into the vitreous by the elevated intravascular pressure can cause vitreous swelling and secondary angle closure.
226
Why is succinylcholine and ketamine not recommended for use in examining a patient with a possible ruptured globe under anesthesia?
Both agents can raise IOP and cause further prolapse of intraocular contents through the wound.
227
A 38-year-old woman complaining of blurred vision and halos in her right eye presents with corneal edema in her right eye, minmal corectopia, normal IOP and broad based peripheral anterior synechiae. What is the probable diagnosis?
Chandler's syndrome, a one of the iridocorneal endothelial syndrome, is characterized by severe corneal changes. Corectopia may be mild to moderate. Stromal atrophy is absent in about 60% of cases. Glaucoma is usually less severe than in Cogan-Reese syndrome and progressive iris atrophy, and the IOP may be normal at presentation.
228
How do do you distinguish between Rieger's anomaly and progressive iris atrophy, both of which are characterized by peripheral anterior synechiae, iris stromal atrophy, hole formation, and corectopia?
Rieger's anomaly, an autosomal dominant trait, is usually bilateral and occurs in childhood or early adulthood. An anteriorly displaced Schwalbe's line (posterior embryotoxon) is present. Progresive iris atrophy, which is one of the iridocorneal endothelial syndromes, typically affects one eye in young to middle-aged woman. The endothelium may have a beaten-metal appearance similar to Fuch's dystrophy. Posterior embryotoxon is not present.
229
What could Cogan-Reese syndrome be misdiagnosed as?
Diffuse iris melanoma.
230
An infant presents with a dense, white central corneal opacity in both eyes with iris adhesions to its margins. The lens cannot be visualized. What is the probable diagnosis?
Peter's anomaly.
231
What complications are patients with Sturge-Weber syndrome, who have glaucoma, at high risk for if trabeculectomy is attempted?
Intraoperative choroidal effusion and expulsive hemorrhage.
232
What is the most common complication seen following Nd:YAG and argon laser iriotomies?
Acute glaucoma.
233
Which laser iridotomy has a greater chance of spontaneous closure, Nd:YAG or argon laser iridotomy?
Ng:YAG laser iridotomy.
234
Which of the following drugs is the most potent ocular hypotensive agent among topical beta-blockers: timolol, betaxolol, levobunolol, carteolol, and metipranolol?
Timolol, levobunolol, metipranolol and carteolol are all equivalents to each other in terms of IOP-lowering effect, while betaxolol is less effective as an ocular hypotensive agent when compared to the other topical beta-blockers.
235
What drug when added to betaxolol will produce an ocular hypotensive effect equivalent to timolol and other beta-blockers?
Dipivefrin.
236
What is the success rate of a primary trabeculectomy (without antimetabolites) in ptaients with open angle glaucoma?
Approximately 80-85%.
237
What are the appropriate laser setting when performing argon laser trabeculoplasty?
50 μm spot size, 0.1 sec duration, initial power setting between 600 to 800 mW and then adjusted to obtain a blanch or small bubble formation.
238
Approximately what percentage of eyes of patients with open angle glaucoma respond to initial therapy with argon laser trabeculoplasty?
According to the Glaucoma Laser Trial, 80% of individuals responded with at least a 20% reduction in intraocular pressure.
239
What is the postulated mechanism by which argon laser trabeculoplasty lowers IOP?
Trabecular outflow is increased due to shrinkage of adjacent tissues and opening of the trabecular channels. In addition, there may be acceleration of the phagocytic activity of the trabecular cells.
240
Following argon laser trabeculoplasty, what is the incidence of a postoperative IOP elevation of >10 mmHg?
Approximately 8%. The use f apraclonidine has decreased this incidence of 2%.
241
How do you define threshold in perimetry?
It is differential light sensitivity at which a stimulus of given size and duration of presentation is seen 50% of the time. In practical terms, it is the dimmest spot detected during testing.
242
What is an isopter?
It is a line connecting points with the same threshold on a visual field representation.
243
What is the most serious idiosyncratic hematologic side effect of carbonic anhydrase inhibitors?
Aplastic anemia.
244
How much of the enzyme carbonic anhydrase must be inhibited in order to reduce aqueous flow significantly?
99%
245
What carbonic anhydrase inhibitor is available for topical use, and how effective is it in lowering IOP?
Dorzolamide hydrochloride 2% administered three times a day effectively reduces IOP and avoids the systemic side effects of oral administration of carbonic anhydrase inhibitors. The IOP lowering effect is about 5 mm throughout the day in clinical studies up to 1 year's duration.
246
How effective is betaxolol's ability to lower IOP when compared to timolol?
Betaxolol is about 85% as effective in lowering IOP as timolol. However, the deficit can be made up by its greater additive effect in combined therapy with epinephrine or dipivefrin.
247
What is the aim of medical therapy of low-tension glaucoma?
Medical therapy is aimed at rapidly reducing IOP to the lowest level possible in order to enhance vascular perfusion of the optic nerve, not just at treating on the basis of extent of cupping and field loss.
248
What systemic medications have some favorable therapeutic effect on low-tension glaucoma?
Calcium channel blockers and the anti-serotonin agent nastidrofuryl are vasodilators and may be useful in treating low-tension glaucoma.
249
What are the most common causative organisms in filtering bleb-associated endophthalmitis?
Haemophilus or Streptococcus species
250
What laser settings are used to release scleral flap sutures after trabeculectomy?
Argon laser, 50 micron spot, 0.1 second duraton, Power 200-600 mW.
251
What are some patient characteristic associated with an increased risk of suprachoroidal hemorrhage?
Advanced glaucoma, high preoperative IOP, aphakia, vitrectomized eyes, systemic vascular disease, and patients with uncontrolled hypertension.
252
What two questions did the Ocular Hypertension Treatment Study (OHTS) set out to answer?
1. Does lowering IOP prevent or delay the onset of glaucoma? 2. What are the risk factors for converting from ocular hypertension (OHT) to glaucoma?
253
What was the conclusion of the Ocular Hypertension Treatment Study (OHTS) with regards to whether lower IOP prevents or delays glaucoma?
In this study, 1500 OHT patients were randomized either to observation or to treatment with IOP-lowering medications. After five years, 9.5% of the control group developed early signs of glaucoma while only 4.4% in the treated group did so. Treating OHT therefore prevents the onset of glaucoma.
254
What are the six risk factors for converting from ocular hypertension to glaucoma identified by the Ocular Hypertension Treatment Study?
1. Older age. 2. Higher untreated IOP. 3. Increased cup-to-disc diameter. 4. Decreased central corneal thickness. 5. African descent.
