Lens and Cataract (BCSC 2016-2017)
What is the rate of cataract surgery in developed countries?
Up to 50 per million population per year
Up to 1000 per million population per year
Up to 10,000 per million population per year
Up to 50,000 per million population per year
What is a normal change in the human crystalline lens as it ages?
It develops an increasingly curved shape, resulting in more refractive power
It becomes increasingly flat, resulting in less refractive power
There is an increase in the index of refraction as a result of the decreasing presence of insoluble protein particles
There is a decrease in the index of refraction as a result of the decreasing presence of insoluble protein particles
How is metabolic waste removed from the crystalline lens?
It is broken down by lysosomes
It is removed by the venous system of the lens
It is stored in the lens, not removed, contributing to the increase in lens size throughout life
It is removed via the aqueous humor
Why are glutathione and vitamins E and C present int he anterior chamber?
To adjust the pH and act as a buffer
To protect the corneal endothelium
To act as a free radical scavenger
To induce DNA damage
On what presumption is the Helmholtz theory of accommodation based?
Most of the change in lens shape occurs at the central anterior lens surface
The action of the anterior zonular fibers on the lens during accommodation results in flattening of the central anterior lens surface
The change in curvature of the posterior lens capsule contributes approximately 25% of the accommodative amplitude
As the ciliary muscle contracts, the zonular tension increases, resulting in bulging of the lens and increasing the dioptric power of the eye
What change occurs in the lens in the presence of high levels of glucose?
Glucose that is not phosphorylated to G6P enters the Krebs cycle
Hexokinase activity increases until all glucose is phosphorylated
Aldose reductase activity increases
Sorbitol is produced and then eliminated from the lens via diffusion through the capsule into the anterior chamber
What process occurs in the crystalline lens during terminal differentiation?
Lens epithelial cells elongate into lens fibers
The mass of cellular proteins is decreased
Glycolysis assumes a lesser role in metabolism
Cell organelles increase their metabolic activity
What process results in formation of the Y-sutures seen in the adult lens
Connection of the adult nucleus to the surrounding cortex
Scarring from the tunica vasculosa lentis
Elaboration of the adult nucleus around the fetal nucleus
Fusion of the embryonic cells within the fetal nucleus
A 30-year-old patient with Marfan syndrome presents with a new report of visual difficulty. Examination reveals early lens subluxation. What would be the best initial management strategy?
Planning for early lens extraction
Addition of prism to the patient's current prescription for glasses
Refraction with attention to presbyopic correction
Treatment with miotic eyedrops
What is a common symptom of cortical cataracts?
Better near vision than distance vision
Abrupt myopic shift
Glare under mesopic lighting conditions
Diminished color perception
What is the histologic change most commonly associated with posterior subcapsular cataracts?
Increased number of lamellar membrane whorls
Posterior migration of lens epithelial cells
Calcium deposition
Glycosaminoglycan deposits in the lens cell bodies
What type of cataract is associated with chalcosis?
Oil droplet cataract
Anterior subcapsular cataract
PSC
"sunflower" cataract
A patient presents with a mature lens and secondary glaucoma without evidence of pupillary block. What is the most likely diagnosis?
Phacomorphic glaucoma
Phacolytic glaucoma
Phacoantigentic uveitis
Lens particle glaucoma
If a patient has a dense, white cataract and the posterior pole is not visible, what test would be most helpful in determining whether cataract surgery is likely to improve vision?
Specular microscopy
B-scan ultrasonography
Potential acuity pinhole test
Fluorescein angiography
A patient with nuclear sclerosis asks whether her cataract is "ripe" enough to be removed. What information would best allow the surgeon to answer appropriately?
Snellen acuity
Glare test results documenting the level of decreased vision required for cataract surgery reimbursement under the patient's insurance plan
The patient's confession that she does not feel comfortable driving at night because of glare but needs to continue to do so
Documentation of significantly decreased contrast sensitivity
Determining the axial length with an immersion technique or contact applanation is most appropriate in which setting?
Posterior chamber filled with silicone oil
Aphakic patient
History of corneal refractive surgery
Dense vitreous hemorrhage
On the day of surgery, a patient arrives 30 minutes late to the surgery center. The order of cases is changed as a result, and another patient is taken to the operating room earlier than planned. What step would prevent the surgeon from placing an incorrect IOL?
Performing a "time-out" to confirm the patient's name and operative eye
Having all lens implants for the day's cases available in the operating room before the start of surgery
Reviewing the patient's IOL calculations and ocular measurements immediately before the start of surgery
Designating one staff member to be responsible for the lens choice
A patient with a medical history significant for hypertension, diabetes mellitus, and coronary artery disease with cardiac stent placement is brought to the operating room for cataract surgery. Anesthetic is administered via a retrobulbar injection. Soon afterward, the orbit is taut, and the eye is noted to be proptotic, with significant ecchymosis of the eyelids and conjunctiva. The eye is extremely firm to palpation. What would be the most appropriate course of action?
Perform ocular massage
Request that the anesthesiologist decrease IV sedation
Examine the fundus to assess whether globe penetration has occurred
Perform a lateral canthotomy and cantholysis
An elderly patient is seen in the office, and slit-lamp examination reveals dense nuclear sclerotic cataracts and severe blepharitis. What would be the most appropriate course of action to prevent postoperative endophthalmitis?
Plan to scrub the eyelids and lashes vigorously with 10% povidone-iodine soap on the day of surgery.
Plan to use IV antibiotics in the irrigating solution.
Plan for an extracapsular cataract extraction to minimize repeated manipulation of instruments in the eye and over the eyelashes.
Recommend eyelid hygiene to the patient, and have the patient return for re-evaluation before surgery.
While examining a patient for cataract surgery, the ophthalmologist notes that although the cornea is clear, there are significant cornea guttae. How would the ophthalmologist manage this patient intraoperatively?
Increase the use of a cohesive ophthalmic viscosurgical device (OVD) during phacoemulsification.
Increase the use of a dispersive OVD during phacoemulsification.
Perform vigorous hydrodissection to prolapse the lens into the anterior chamber and minimize the amount of energy needed to create a groove in the nucleus.
Prepare for possible penetrating keratoplasty by having corneal tissue available in the operating room
What is the best initial treatment of a postoperative shallow anterior chamber caused by ciliary block glaucoma?
Cyclophotocoagulation
Cycloplegia and aqueous suppression
Miotics and peripheral iridotomy
Nd:YAG laser posterior capsulotomy
What systemic medication is most likely to cause severe intraoperative floppy iris syndrome (IFIS)?
Alfuzosin
Doxazosin
Tamsulosin
Terazosin
What is the most characteristic finding on examination of a patient with blurred vision and toxic anterior segment syndrome (TASS?)
Hypopyon that presents 3-7 days postoperatively
Diffuse corneal edema that presents 1 day postoperatively
Elevated intraocular pressure with central corneal epithelial edema
Ocular pain with cells in the anterior vitreous
What type of IOL implant is most likely to cauase negative dysphotopsia?
Anterior chamber IOL
Decentered multifocal IOL
Sulcus-fixated 1-piece acrylic IOL
Square-edge posterior chamber IOL in the capsular bag
What is an appropriate indication for combined keratoplasty and cataract extraction?
Nuclear cataract and irregular corneal astigmatism due to epithelial basement membrane dystrophy
Nuclear cataract and Fuchs endothelial dystrophy with vision worse in the morning
Recurrent herpes simplex keratitis with peripheral corneal scarring and moderate nuclear cataract
Brunescent cataract and cornea guttata with normal corneal thickness
What test is useful int he calculation of IOL power for a patient who has previously undergone LASIK?
Corneal topography
Optical coherence tomography of the macula
B-scan ultrasonography
A-scan ultrasonography
A surgeon encounters IFIS after phacoemulsification has begun. What procedure would allow the surgeon to best manage the miotic pupil and floppy iris?
Insertion of 4 or 5 iris hooks through new corneal incisions
Insertion of a pupil expansion device (eg, Malyugin ring)
Insertion of a high-viscosity OVD and bimanual pupil stretching
Insertion of a capsular tension ring
A patient has a white, intumescent cataract. In addition to the standard supplies and instruments for cataract surgery, what should the surgeon have ready for use in this patient?
Malyugin ring
CTR
Lens chopper
Trypan blue dye
During phacoemulsification, the surgeon realizes the zonular dialysis of 3 clock-hours (90 degrees) is present. How should the surgeon proceed?
Increase the bottle height and flow rate to maintain adequate anterior chamber depth
Close the corneal incision, and convert to an extracapsular cataract extraction with a superior corneoscleral incision
Proceed with phacoemulsification, and place an anterior chamber IOL
Place a CTR, complete phacoemulsification, and insert a posterior chamber IOL
What procedure is best suited for cataract extraction in an eye with controlled uveitis and a small pupil?
Pupil stretching and lysis of any posterior synechiae, followed by phacoemulsification and placement of an acrylic IOL
Malyugin ring insertion, followed by phacoemulsification and placement of a silicone IOL
Insertion of iris hooks, followed by phacoemulsification without IOL insertion
Extracapsular cataract extraction
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