Cataract Lens rEPLACEMENT By: Paul Rizzo and Harry Ramsamooj
Vision Light passes through the cornea, the transparent front covering of the eye. It continues through the pupil, the size of which is regulated by the iris. The lens refracts (bends) light to focus it onto the retina. The retina contains rod cells and cone cells, which transmit the stimulus to the optic nerve. The optic nerve sends the signal to the brain
The Anatomy of the Eye
Function of the Lens
Structure of the Lens The lens consists of three structures: Lens Capsule: This is a smooth, transparent membrane of collagen and GAGs. It is transparent and elastic to allow the lens to bend. Lens Epithelium: Cells of this simple cuboidal epithelium have Na+/K+ ATPase pumps, which export water and import vital nutrients. The epithelial cells also serve as progenitors of the lens fibers. Lens Fibers: These elongated cells have gap junctions that keep them packed tightly and in parallel layers (laminae) along the lens. They have no nuclei or organelles. The lens is transparent because: The lens fibers are densely packed and lack organelles. It is avascular. It contains little water.
Cataracts A clouding of the lens inside the eye which leads to a decrease vision. Cataract surgery is the commonest single surgical procedure carried out in the developed world. Clouding is caused by new lens fibers continuing to form while old fibers are not replace, but instead remain there. One of the few structures of the body that continue to grow during life.
Causes of Cataracts Age Trauma Radiation Genetics Skin diseases Drug use
ICCE Intracapsular Cataract Extraction The lens and surrounding capsule are removed in one piece Requires the largest incision High complication rate and slow recovery due to the incision size Sutures required to close the wound Patient wears an eye patch during recovery Rarely used
ECCE Extracapsular cataract extraction Used for advanced cataracts where the lens is too dense to phacoemulsify Larger incision to remove the lens in one piece Incision closed with sutures at the end of surgery Slow recovery Performed less frequently than phacoemulsification
MSICS Manual Small Incision Cataract Surgery Lens is removed through a small, self-sealing scleral tunnel (no sutures) Although the incision is small (5.5 mm), it is still larger than the incision in phacoemulsification Popular in the developing world
Phacoemulsification Most modern type of cataract surgery Most common Takes 15-20 minutes, requires minimal sedation Small incision (2.8-3.5 mm) No sutures needed to close the wound Fastest recovery time
Phacoemulsification Surgical: Anesthesia Corneal incision Capsulorhexis Phacoemulsification Irrigation and Aspiration Lens insertion Salt water Injection
Cost of Treatment Varies based on the type of lens implanted $2699-$4337 Covered by most insurance Types of Intraocular Lens Monofocal Multifocal Presbyopia-correcting Astigmatism-correcting (toric)
Biomaterials Involved PMMA Silicone Acrylic
Recovery Short post-op recovery time Advised to avoid straining or heavy lifting for a month Eye shield used at night
Benefits/Complications of Procedure Improved vision i.e. less cloudy, sharper images Can correct nearsightedness/farsightedness Consequences Retinal detachment Endophthalmitis Corneal/cystoid macular edema Posterior capsular opacification
Crystalens Bausch & Lomb First and only FDA-approved IOL that uses the natural focusing ability of the eye In clinical trials, patients implanted with a Crystalens (88.4%) could see better at all distances than patients implanted with a standard IOL (35.9%)
Thank you!
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