BCSC Lens and Cataract Flashcards
1
Q
What are the functions of the crystalline lens?
A
1) to maintain its own clarity
2) to refract light
3) to provide accomodation
2
Q
Does the lens have a blood supply after fetal development?
A
No. It depends on the aqueous to meet its metabolic requirements.
3
Q
What are the basic components of the lens?
A
1) capsule
2) lens epithelium
3) cortex
4) nucleus
4
Q
What is the equator of the lens?
A
The greatest circumference in the coronal plane
5
Q
What amount of refractive power does the lens contribute to the eye?
A
15-20D (of the 60D total, the other 40-45 is provided by the cornea)
6
Q
Does the lens continue to grow throughout life?
A
Yes
7
Q
What is the diameter of the equator of the lens at birth?
A
6.4mm
8
Q
What is the diameter of the equator of the lens in an adult eye?
A
9mm
9
Q
How does the shape of the lens change with age?
A
It becomes more curved, giving it more refractive power
10
Q
Of what is the lens capsule composed?
A
Type IV collagen laid down as a basement membrane by the lens epithelial cells
11
Q
What is the zonular lamella?
A
the outer layer of the lens capsule, which serves as the point of attachment for the zonular fibers
12
Q
Where is the lens capsule thickest?
A
anterior and posterior preequatorial zones of the lens
13
Q
Where is the lens capsule thinnest?
A
the central posterior pole of the lens
14
Q
Of what do zonular fibers consist?
A
microfibrils of elastic tissue
15
Q
From where do the zonules originate?
A
From the basal laminae of the nonpigmented epithelium of the pars plana and pars plicata of the ciliary body
16
Q
Where do the zonular fibers insert on the lens capsule?
A
in the equatorial region (1.5mm anterior to equator and 1.25mm posterior to the equator)
17
Q
How many layers of epithelial cells are beneath the anterior lens capsule?
A
Only one
18
Q
What is the germinative zone of the lens?
A
a ring of epithelial cells in the anterior equatorial lens that have high rates of mitotic activity
19
Q
To where do newly formed lens epithelial cells (in the germinative zone) migrate?
A
Toward the equator, where the epithelial cells differentiate into fibers
20
Q
What is the bow region of the lens?
A
The region where newly formed epithelial cells that have differentiated into fibers subsequently terminally differentiate into lens (cortical) fibers. This region is deep to the epithelium.
21
Q
Are cells lost from the lens?
A
No
22
Q
Where are the oldest fibers within the lens?
A
In the center of the lens
23
Q
What are the oldest fibers in the lens?
A
The embryonic and fetal lens nuclei
24
Q
What are the lens sutures?
A
The Y-shaped patterns formed by the interdigitations of apical cell processes anteriorly and posteriorly. They are visible at the slit-lamp.
25
Is the concentration of protein in the lens higher or lower than that of most other tissues in the body?
Higher -- about 2x as much as most other tissues (33% of its wet weight).
26
What are the predominant proteins found in the lens?
Crystallins (alpha, beta, gamma)
27
What percentage of lens proteins is water soluble?
80% (the crystallins)
28
Into which groups are the water-insoluble lens proteins commonly divided?
Urea soluble and urea insoluble
29
Which water insoluble proteins are urea soluble?
Most cytoskeletal proteins
30
Which water insoluble proteins are urea insoluble?
Most lens fiber cell membrane proteins, including major intrinsic protein.
31
How does protein aggregation affect lens translucency?
Protein aggregation increases light scatter, creating lens opacities. Protein aggregation increases with age.
32
With what does the degree of opacification correlate in brunescent cataracts?
The proportion of water-insoluble protein
33
To what does depletion of reduced glutathione lead?
accelerated protein cross-linking, protein aggregation, and light scattering
34
On what does energy production in the lens primarily rely?
glucose metabolism
35
Which pathway is responsible for most of the high-energy phosphate bonds required for lens metabolism?
anaerobic glycolysis
36
Does the lens require oxygen for normal metabolism?
No. However, aerobic metabolism does occur naturally in the lens despite the low oxygen tension in the lens, and is responsible for 25% of the ATP generated.
37
What happens to glucose that is not phosphorylated to G6P in the lens?
it enters the sorbitol pathway or is converted to gluconic acid
38
What does the accumulation of sorbitol (as seen in hyperglycemic states) cause in the lens?
Increase in osmotic pressure, drawing in water
39
What type of cataract is typically formed as a result of long-term hyperbaric oxygen therapy?
Nuclear sclerotic
40
Which molecules serve as free radical scavengers?
glutathione, catalase, superoxide dismutase
41
How is communication between older cells and younger cells in the lens accomplished?
Through low-resistance gap junctions that facilitate the exchange of small molecules from cell to cell
42
Is disruption of water and electrolyte balance a feature of nuclear cataracts?
No, but it is a feature of cortical cataracts
43
Does the lens have higher or lower levels of potassium ions (K+) than its surrounding aqueous and vitreous?
Higher
44
Is active transport required for maintenance of lens ionic balance?
Yes, via the Na/K/ATPase pump
45
What is the primary site of active transport in the lens?
the epithelium
46
Does zonular tension increase or decrease with accommodation?
decrease
47
Does the ciliary body contract or relax during accommodation?
Contract
48
Which surface of the lens (anterior or posterior) changes in curvature to a greater extent during accommodation?
the anterior surface of the lens
49
What is the amplitude of accommodation?
The amount of change in the eye's refractive power that is produced by accommodation
50
At which day of gestation does formation of the lens begin?
25 days
51
The lens capsule develops as a basement membrane elaborated by what?
The lens epithelium anteriorly and the lens fibers posteriorly
52
What are the primary lens fibers?
The fibers that make up the embryonic lens nucleus, which will occupy the center of the lens in adult life
53
The fetal nucleus is comprised of what?
The secondary lens fibers, which are formed between 2 and 8 months of gestation
54
Is the upright Y-suture anterior or posterior within the lens?
Anterior
55
What is the mass of the lens at birth?
90mg
56
What is the rate of increase in lens mass per year?
2mg per year
57
What is the tunica vasculosa lentis?
a network of capillaries arising frmo the hyaloid artery that anatomose with a second network of capillaries (the anterior pupillary membrane) to envelop the lens
58
What is a Mittendorf dot?
a remnant of the tunica vasculosa lentis (on the posterior aspect of the lens)
59
What is a persistent pupillary membrane?
a remnant of the anterior pupillary membrane (on the anterior aspect of the lens)
60
By what are the zonules of Zinn secreted?
By the ciliary epithelium
61
In which form of congenital aphakia is the lens spontaneously absorbed?
secondary aphakia
62
Which form of lenticonus is more common -- anterior or posterior?
Posterior
63
With what is anterior lenticonus often associated?
Alport syndrome
64
Are zonular attachments in the region of a lens coloboma usually weak?
Yes, weak or absent
65
What does the site of a Mittendorf dot indicate?
the location at which the hyaloid artery came into contact with the posterior surface of the lens in utero
66
Which embryologic event fails to happen in Peters anomaly?
separation of the lens vesicle from the surface ectoderm
67
Peters anomaly is a part of what spectrum of disorders?
anterior segment dysgenesis syndromes
68
What are the clinical characteristics of microspherophakia?
small diameter lens that is spherical in shape
69
What refractive error is generally seen in microspherophakia?
high myopia
70
What are common lens findings seen in Peters anomaly?
1) adhesions between lens and cornea
2) anterior cortical or polar cataract
3) misshapen lens displaced anteriorly into the pupillary space and the anterior chamber
4) microspherophakia
71
What is the most common association of microspherophakia?
Weill-Marchesani syndrome (AR)
72
What are the syndrome associations of microspherophakia other than Weill-Marchesani syndrome?
1) Peters anomaly
2) Marfan syndrome
3) Alport syndrome
4) congenital rubella
73
What type of glaucoma can occur in patients with microspherophakia?
Secondary angle closure glaucoma due to pupillary block by the round lens
74
Which types of cataracts are often seen in aniridia?
cortical, subcapsular, and lamellar
75
Within what period of time must a cataract be present to be termed a congenital cataract?
within the first year of life
76
What is the appearance of a lamellar cataract when viewed from the front?
disc-shaped
77
What is the most common form type of congenital cataract?
Lamellar cataract
78
In what pattern are anterior polar cataracts usually inherited?
Autosomal dominant
79
Where are the bluish opacities generally seen in a cerulean cataract?
In the lens cortex
80
Is a subluxated lens separated from all its zonular attachments?
No, but a luxated lens is.
81
What is the most common cause of acquired lens displacement?
Trauma
82
What are common non-traumatic causes of ectopia lentis?
1) Marfan syndrome, 2) homocystinuria, 3) aniridia, 4) congenital glaucoma
83
What is the usual direction of lens dislocation in Marfan syndrome?
Superotemporal
84
What is the usual direction of lens dislocation in homocystinuria?
Inferonasal
85
Do nuclear cataracts typically cause greater impairment of distance vision or near vision?
distance vision
86
What are the first signs of cortical cataract formation visible with the slit-lamp?
vacuoles and water clefts in the anterior or posterior cortex
87
What is a sign that a cataract is hypermature?
wrinkling and shrinking of the lens capsule (due to leakage of degenerated cortical material through the capsule)
88
What is a morgagnian cataract?
a hypermature cataract with such a high degree of cortical liquefaction that the nucleus is able to move freely within the capsular bag (and is often displaced)
89
What is generally the first sign of PSC formation?
iridescent sheen in the posterior cortical layers visible with slit lamp
90
What are Wedl (bladder) cells?
aberrantly enlarged lens epithelial cells that have migrated posteriorly from the lens equator seen in PSC cataracts
91
What is seen in the later stages of a PSC cataract?
granular opacities of the posterior subcapsular cortex
92
What are common associations of PSC cataracts?
1) trauma, 2) steroids, 3) ionizing radiation, 4) alcoholism
93
Can steroid induced PSC cataracts resolve after discontinuation of the drug in children?
Yes, in children, but generally not in adults
94
Can PSC cataracts due to steroids be distinguished from those due to aging on histology?
No
95
What is the typical appearance of cataracts caused by phenothiazines?
anterior spokes emanating from the visual axis (although usually visually insignificant)
96
What is the typical early appearance of a cataract caused by an anticholinesterase?
anterior cortical vacuoles
97
What percentage of patients using pilocarpine for > 55 months experience cataract formation?
20%
98
What pattern of cataract is typically caused by amiodarone use?
stellate pigment deposition in anterior cortex
99
What is a Vossius ring
a ring of pigment from the pupillary ruff imprinted on the anterior surface of the lens after blunt impact
100
What is the initial manifestation of a cataract due to blunt injury?
stellate or rosette-shaped opacification (rosette cataract)
101
Where does opacification generally occur in penetrating injury to the lens?
focal cortical opacification, which often progresses to complete cortical opacification
102
What type of cataract is associated with true (glassblower/infrared radiation) exfoliation syndrome?
cortical cataract, with peeling off (exfoliation) of the lens capsule as a single layer
103
For what percentage of risk of cortical cataracts does UV radiation account?
10%
104
What is siderosis bulbi?
The deposition of iron molecules in TM, lens epithelium, iris, and retina due to iron-containing intraocular foreign body
105
What kind of cataract can be formed due to intraocular copper-containing foreign body?
Sunflower cataract
106
With which other findings is a sunflower cataract in chalcosis usually associated?
deposition of copper in Descemet membrane, iris heterochromia
107
What findings can be seen in cataract due to electrical injury?
Anterior mid-peripheral cortical vacuoles and linear opacities in anterior subcapsular cortex
108
What is the typical pattern of an acute diabetic cataract?
"Snowflake" pattern, consisting of bilateral widespread subcapsular gray-white opacities (anteriorly and posteriorly)
109
Do age-related cataracts occur earlier or later in patients with diabetes than in the general population?
earlier in DM
110
Which enzyme is the most commonly implicated in galactosemia?
G1P-UT (galactose 1-phosphate uridyltransferase)
111
What is the typical appearance of a cataract in galactosemia?
"oil-droplet" appearance, with opacification of the nucleus and deep cortex
112
What is the typical pattern of a hypocalcemic cataract?
Punctate iridescent opacities in anterior and posterior cortex
113
What is the typical pattern of a cataract in Wilson disease?
Sunflower cataract (also seen in copper-containing IOFB)
114
What is the typical pattern of lens opacification seen in myotonic dystrophy?
polychromatic iridescent crystals (whorls of cell membranes) in lens cortex followed by PSC
115
What is the typical pattern of lens opacification seen in Fuchs heterochromic iridocyclitis?
cortical cataract
116
What type of cataract is seen in patients undergoing hyperbaric oxygen therapy?
Nuclear sclerotic cataract (often with associated myopic shift)
117
What is the typical pattern of cataract seen in atopic dermatitis?
shield-like anterior subcapsular opacities, occurring usually in the 2nd to 3rd decade of life
118
What is commonly the trigger for phacoantigenic uveitis?
The release of a large amount of lens protein into the AC, disrupting immunologic tolerance and causing a severe inflammatory reaction.
119
What is the mechanism of phacolytic glaucoma?
leakage of liquefied HMW lens proteins through an intact but permeable lens capsule (usually with mature or hypermature cataract) --> blockage of TM by engorged macrophages
120
Is phacolytic glaucoma an open or closed angle glaucoma?
Open
121
Is the onset of pain in phacolytic glaucoma gradual or abrupt?
Usually abrupt, despite having an open angle.
122
What is the mechanism of lens particle glaucoma?
blockage of the TM by lens material (usually after phaco or penetrating trauma)
123
Is the angle usually open or closed in lens particle glaucoma?
Open
124
What is the usual delay in onset of lens particle glaucoma after penetrating trauma or surgery?
days to weeks
125
What is the mechanism of phacomorphic glaucoma?
Intumescent cataractous lens (or other abnormally shaped lens) causes pupillary block and secondary angle closure (or pushes the iris forward and causes a narrow angle)
126
Is phacomorphic glaucoma an open or closed angle glaucoma?
A closed/narrow angle glaucoma
127
What are glaucomflecken?
Necrotic lens epithelial cells and degenerated subepithelial cortex that present as gray-white opacities in anterior lens after episode of high IOP
128
What percent of blindness is thought to be reversible blindness due to cataracts worldwide?
48% (17 million individuals)
129
Do smokers have an increased risk of developing nuclear lens opacities?
Yes
130
Do PSC cataracts have a greater impact on near or distance visual acuity?
Near visual acuity
131
Do oil droplet cataracts have a greater impact on near or distance visual acuity?
Distance visual acuity (they cause a myopic shift)
132
Which medications are associated with intraoperative floppy iris syndrome (IFIS)?
alpha1a-adrenergic antagonists (prazosin, terazosin, doxazosin, tamsulosin)
133
For how long before cataract surgery should an eye ideally be quiet without the use of topical corticosteroids?
3 months
134
Can dilation improve visual acuity in patients with cataracts?
Yes, especially in those with PSCs
135
If ACIOL implantation is anticipated, what needs to be done as part of the pre-operative evaluation that otherwise might not be done?
Gonioscopy
136
What form of evaluation of the posterior segment is warranted in the pre-operative evaluation of a dense white cataract?
B-scan ultrasonography
137
In patients with high hyperopia, compression of the eye by 1mm during contact applanation A-scan ultrasonography can result in how large an error in IOL power?
3.75 diopters error
138
What is "white to white" distance?
A term commonly used to refer to corneal diameter
139
What features of endothelial cells on specular microscopy may indicate a propensity for corneal decompensation after cataract surgery?
Polymegathism (varying degrees of enlargement) and polymorphism (varying shapes)
140
Are measurements of corneal power and axial length required to determine IOL power when using intraoperative aberrometry?
No
141
What is the axial length of the eye when used in IOL calculations?
The distance from the anterior surface of the cornea to the fovea
142
What is an A constant?
A dimensionless constant relating the power of a particular IOL to axial length and keratometry
143
What is the SRK formula for IOL power prediction to achieve emmetropia?
P = A - (2.5L) - 0.9K
P is the IOL power
A is the A-constant of the specific IOL used
L is the axial length of the eye
K is the average keratometric reading in diopters
144
What are three common types of methods for calculating corneal power for IOL prediction in a patient who has undergone refractive surgery?
1) Contact lens method
2) Topographical method
3) Historical method
145
How is corneal power determined by the contact lens method?
K = base curve + power + overrefraction - spherical equivalent of MRx without CL
146
How is corneal power determined by the topographical method?
central keratometric power = [central topographic power * (376/337.5)] - 4.9
147
How is corneal power determined by the (Hoffer) historical method?
```
K2 = K1 + SE_1 - SE_2
K1 = K before refractive surgery
SE_1 = spherical equivalent refractive error before refractive surgery
SE_2 = spherical equivalent refractive error after refractive surgery
```
148
What does modern extracapsular cataract extraction (ECCE) involve?
removal of the lens nucleus and cortex through an opening in the anterior capsule, with the capsular bag left in place
149
What are the advantages of manual small incision cataract surgery (MSICS) over ECCE?
smaller scleral groove (7-8mm vs. 12-14mm); CCC instead of can-opener rhexis; wound suturing is optional; lens may be expressed in pieces rather than whole
150
What does OVD stand for?
Ophthalmic Viscosurgical Device
151
What are the common components of OVDs (viscoelastics)?
1) sodium hyaluronate, 2) chondroitin sulfate, 3) hydroxypropyl methylcellulose
152
What is the half-life of sodium hyaluronate in the AC?
1 day in aqueous (3 days in vitreous)
153
From what is chondroitin sulfate usually obtained?
Shark cartilage
154
What does viscoelasticity mean?
It refers to the ability of a compound to act as a viscous agent when imparted with low frequency energy and as an elastic agent (or gel) when imparted with high frequency energy
155
What is pseduoplasticity?
the ability of a substance to transform from a gel to a liquid-like substance when under pressure (e.g. be forced through a cannula while maintaining shape in AC)
156
Does a viscoelastic with high surface tension coat substance more or less effectively than one with low surface tension?
less effectively. Low surface tension --> better coating, but harder to remove from eye
157
What are examples of cohesive viscoelastics?
Healon, Healon GV, Amvisc
158
What are examples of dispersive viscoelastics?
Ocucoat, Viscoat, Healon Endocoat
159
Do dispersive viscoelastics have high or low surface tension?
Low surface tension
160
Who described the modern technique of retrobulbar anesthesia?
Atkinson
161
What are the two key results of retrobulbar anesthesia?
Ocular akinesia and anesthesia
162
Where is anesthetic solution introduced in peribulbar anesthesia?
external to the muscle cone, underneath Tenon capsule
163
Which nerves are blocked by retrobulbar anesthesia?
Ciliary nerves, CN II, CN III, and CN VI
164
What are advantages of topical anesthesia for cataract surgery?
1) no risk of ocular perforation/EOM injury/CNS depression
| 2) vision returns almost immediately
165
What are disadvantages of topical anesthesia for cataract surgery?
1) increased extracoular motility
2) blepharospasm
3) patient discomfort
166
What is cavitation?
The formation of gas bubbles in the aqueous in response to pressure changes at the tip of the phaco needle. The implosion of these bubbles results in heat and pressure liberation at the phaco tip, resulting in emulsification of lens material
167
What is chatter?
The back and forth movement of lens material at the phaco tip due to vacuum that is repeatedly overcome by the ultrasonic stroke of the phaco tip
168
What is phaco duty cycle?
The proportion of time during which phaco energy is being delivered in pulsed phacoemulsification
169
What is the common range of frequencies (of needle movement) for ultrasonic phaco handpieces?
27,000 Hz to 60,000 Hz
170
To what does "load" refer in ultrasonics?
The mass of nuclear material in contact with the phaco tip
171
How is power denoted in ultrasonics?
As a percentage of the maximum stroke length of which the needle is capable
172
What is "stroke" in ultrasonics?
the linear displacement of the phaco tip; it commonly varies from 0.05-0.1mm
173
What are the commonly used dimensions for aspiration flow rate?
mL/min
174
What is followability?
the ability of a system to attract and hold an object at the end of a handpiece
175
What is "occlusion" in vacuum terminology?
obstruction of the aspiration port, which leads to a build-up of vacuum until the obstructing material is evacuated
176
What is "rise time" in vacuum terminology?
The rate at which vacuum builds once occlusion of the aspiration port is achieved
177
What is "surge" in vacuum terminology?
The phenomenon of abrupt drawing of intraocular contents to the aspiration tip after vacuum has built up due to occlusion and the occlusion is subsequently broken
178
How is vacuum generally measured?
mmHg. It indicates how well material occluding the phaco tip will be held to the tip
179
What is "venting" in vacuum terminology?
The process by which negative pressure is equalized to atmospheric levels to prevent surge
180
What is set during pulsed-mode phacoemulsification?
The number of pulses per second (each pulse is followed by an equivalent interval without delivery of phaco power). Phaco power varies with foot pedal excursion (0-100%, or less than 100% upper limit if desired).
181
What is set during burst-mode phacoemulsification?
The amount of phaco power delivered (0-100%). The interval between bursts decreases with increasing foot pedal excursion (but a lower limit can be set on this interval).
182
To what is burst-mode phacoemulsification equivalent if the interval between bursts goes to 0?
continuous mode phacoemulsification
183
For what is burst mode phacoemulsification particularly useful?
burying the phaco tip into the lens, which is necessary for chopping techniques
184
What are the 3 types of aspiration pumps used in phaco machines?
1) Peristaltic
2) Diaphragm
3) Venturi
185
Traditionally, which type of aspiration pump has provided the fastest and most linear rise in vacuum?
Venturi pump
186
What is the usual distance (in clock hours) between a main incision and paracentesis?
2 to 3 clock hours
187
What are risks of making a small capsulorrhexis?
1) Difficulty in disassembling the lens
| 2) Possibility of capsular phimosis
188
What are risks of making a large capsulorrhexis?
1) Difficulty in performing endocapsular phaco techniques
| 2) Possibility of anterior dislocation of the IOL optic or haptic
189
What size capsulorrhexis is often advocated?
One that allows the capsular rim to cover the optic edge
190
What is the primary role that OVD plays in performing the CCC?
Keeping the lens flat to avoid radialization of the tear
191
What two crystalline lens components does hydrodelineation separate?
Hydrodelineation separates endonucleus from the softer epinucleus
192
Is hydrodelineation useful in white or densely brunescent nuclei?
Not usually
193
What is lens sculpting?
The process of debulking the central nucleus. It involves a shaving maneuver in which the tip of the phaco needle is never fully occluded.
194
What are the locations traditionally used for phacoemulsification?
1) Anterior Chamber
2) Iris plane
3) Posterior chamber
4) Supracapsular
195
What are common indications that adequate depth has been achieved with the sculpting of the central groove in the divide and conquer technique?
1) smoothing of striations in the groove
2) brightening of the red reflex in the groove
3) sculpting to a depth of 2 to 3 phaco tip diameters
196
For which type of cataracts is chopping generally not helpful?
Soft cataracts, such as pure PSC cataracts
197
What are some techniques for aspiration of subincisional cortex?
1) Use of a 45 degree, 90 degree, or U-shaped aspiration cannula
2) introduction of a separate aspiration port via the paracentesis instead of the main incision
3) viscodissection
4) loosening of cortex with IOL haptics
198
Is cataract surgery considered to be an invasive procedure that induces transient bacteremia?
No. Accordingly, systemic antibiotic prophylaxis is not required.
199
What percent of cataract surgeries result in bacterial innoculation of the anterior chamber?
7-35%
200
Intracameral injection of what medication has been shown to reduce the risk of endophthalmitis after cataract surgery?
Cefuroxime (ESCRS Endophthalmitis Study Group; J Cataract Refract Surg 2006 Mar;32(3): 407–10)
201
Has definitive evidence been obtained indicating that use of topical antibiotics after cataract surgery reduces risk of endophthalmitis?
No
202
By how much is the astigmatic correction reduced for every degree of error in axis of a toric IOL?
3% for each degree
203
What can occur if silicone oil is used in a pseudophakic patient with a silicone IOL?
Adhesion of droplets of silicone oil to the IOL
204
What are disadvantages of traditional multifocal IOLs?
1) reduction in contrast sensitivity
2) Decrease in BVCA
3) Increased glare
4) Increased haloes
205
What is range of rates of posterior capsular or zonular rupture in cataract surgery?
1.5% to 3.5%
206
What is the rate of vitreous loss/anterior vitrectomy or aspiration in cataract surgery?
1.1%
207
What is the range of rates of postoperative CME in cataract surgery?
1.2% to 3.3%
208
What is the range of rates of postoperative endophthalmitis in cataract surgery?
0.1% to 0.2%
209
What is the likely cause of postoperative corneal epithelial edema in setting of compact stroma after cataract surgery?
elevated IOP
210
What is Brown-McLean syndrome?
peripheral corneal edema with a clear central cornea after cataract surgery
211
What happens to a cataract wound that experiences thermal injury from a phaco tip?
contraction of corneal collagen, wound gape, and leakage
212
What are potential causes of detachment of Descemet membrane in cataract surgery?
1) insertion of instrument through the incision
| 2) inadvertent injection of fluid between Descemet membrane and stroma
213
What usually happens in the meridian of the incision in cataract surgery?
flattening
214
What are clinical signs of epithelial downgrowth?
elevated IOP, clumps of cells floating in the AC, visible retrocorneal membrane with overlying corneal edema, abnormal iris surface, pupillary distortion
215
What is Toxic Anterior Segment Syndrome?
severe sterile postoperative intraocular inflammation and corneal edema due to entry of a toxic substance into the AC
216
What are causes of elevated IOP without angle closure after cataract surgery?
1) retained OVD (peak 4-6 hours after surgery)
2) hyphema
3) TASS
4) endophthalmitis
5) retained lens material
6) uveitis
7) iris pigment release
8) pre-existing glaucoma
9) corticosteroid usage
10) vitreous in AC
11) ghost cell glaucoma
12) alpha-chymotrypsin
217
What is the triad of Intraoperative Floppy Iris Syndrome (IFIS)?
1) iris billowing
2) iris prolapse into the incisions
3) progressive pupillary miosis
218
Which drugs are most likely to be associated with IFIS?
Alpha 1-a adrenergic agonists (e.g., tamsulosin)
219
What is Lens-Iris Diaphragm Retropulsion Syndrome (LIDRS)?
High infusion pressure in AC leading to reverse pupillary block. LIDRS is characterized by posterior displacement of the lens-iris diaphragm with marked deepening of the AC, posterior iris bowing, and pupil dilation.
220
With which two bacterial pathogens has chronic uveitis following cataract surgery been associated?
Propionibacterium acnes and Staph epidermidis
221
By what time after cataract surgery should an eye be free of inflammation with current topical regimens?
3-4 weeks after surgery
222
Which is more likely to incite inflammation -- retained cortical or nuclear material?
Nuclear material is more likely to incite infammation
223
How long after initial cataract surgery is PPV for removal of dropped lens material usually performed?
7-14 days
224
What can vitreous in the AC lead to?
Chronic intraocular inflammation with or without CME
225
Which types of lenses were traditionally associated with UGH?
rigid or closed-loop anterior chamber IOLs
226
What is the common description of a negative dysphotopsia?
Arcuate dark or dim region in the temporal visual field
227
What is the etiology of posterior capsule opacification (PCO)?
Continued viability of lens epithelial cells after cataract surgery. Lens epithelial cells proliferate, forming secondary membranes.
228
What are two common forms of proliferation of lens epithelial cells after cataract surgery?
1) Soemmering ring -- donut-shaped configuration between the adherent edges of anterior and posterior capsule
2) Elschnig pearls -- tranlucent globular masses resembling fish eggs on the edge of the capsular opening
229
What type of medication has been seen to reduce PCO when instilled in the capsular bag?
Mitotic inhibitors
230
What is the reported incidence of retinal detachment after YAG laser capsulotomy?
0.1% to 3.6%
231
What is the time of onset of acute postop endophthalmitis in cataract surgery?
3 to 10 days
232
When is PPV for endophthalmitis indicated per the Endophthalmitis Vitrectomy Study (EVS)?
If vision is LP or worse (if HM or better, tap and inject)
233
What are the three most common causes of acute postoperative endophthalmitis in cataract surgery?
Staph epi, Staph aureus, Strep species
234
How long after cataract surgery does CME typically occur?
6 to 10 weeks after surgery
