BCSC 11. Lens & Cataract Flashcards
Rate of cataract surgery in developed countries
Up to 10,000 per million population per year
Normal change in the human crystalline lens as it ages
Develops an increasingly curved shape, resulting in more refractive power
How is metabolic waste removed from the crystalline lens
Aqueous humor
Helmholtz Theory of accommodation
Most of the change in lens shape occurs at the central anterior lens surface
Change that occurs in the Crystalline lens during terminal differentiation
Lens epithelial cells elongate into lens fibers
Process that results in the formation of the Y sutures seen in the adult lens
Fusion of the embryonic cells within the fetal nucleus
Common symptom of cortical cataracts
Glare under mesopic lighting conditions
Lamellar membrane whorls seen on EM
Nuclear cataracts
Cataract a/w chalcosis
“sunflower” cataract - petal-shaped deposition of yellow or brown pigment in lens capsule that radiates from anterior axial pole of lens to equator
Cause of chalcosis
intraocular FB deposits copper in descemet membrane, anterior lens capsule or other intraocular basement membranes.
Cataract occurs in galactosemia and posterior lenticonus
Oil droplet cataract
Must perform this test if dense white cataract
B-scan ultrasonography to r/o RD, posterior staphyloma, occult tumor or posterior pathology that could affect visual outcome
Determining factor for cataract surgery
Elective surgery - Impact of vision changes on patient’s daily activities and lifestyle
Determining axial length with an immersion technique or contact applanation
IF significant corneal scarring, PSC, or vitreous hemorrhage
Approach for eye with corneal guttae
Protecting corneal endothelium with coating agent, DISPERSIVE ophthalmic viscosurgical device (OVD)
Best initial treatment of postoperative shallow anterior chamber caused by ciliary block glaucoma
Cycloplegia and aqueous suppression. If initial medical treatment fails, surgical disruption of vitreous face or vitrectomy at be necessary to restore normal aqueous circulation and AC depth
Cause for severe intraoperative floppy iris syndrome (IFIS)
TAMSULOSIN - selective alpha-1-a adrenergic antagonist has greater effect on iris dilator muscle than nonselective
Painless diffuse corneal edema and blurred vision within hours of surgery
Toxic anterior segment syndrome (TASS)
Elevated IOP shortly after surgery causing decreased vision, pain, central epithelial edema “bedewing”
Retained OVDs
IOL most likely to cause negative dysphotopsia
Square-edge posterior chamber IOL in capsular bag
Indication for combined keratoplasty and cataract extraction
nuclear cataract and Fuchs endothelial dystrophy with vision worse in the morning - indicates significant corneal endothelial function
Useful in IOL power calculation for patient with previous LASIK
Corneal topography
IFIS after phacoemulsification has begun. Procedure to allow surgeon to best manage miotic pupil and floppy iris
Insertion of 4 or 5 iris hooks through new corneal incisions
During phacoemulsification, surgeon realizes zonular dialysis of 3 clock-hours is present
Place a CTR, complete phacoemulsification, insert posterior chamber IOL. Risk of extending dialysis without capsular support
Best procedure for cataract extraction in an eye with controlled uveitis and small pupil
Pupil stretching and lysis of any posterior synechiae, followed by phacoemulsification and placement of an acrylic IOL
