FIG. 7.25 External entry site for standard cataract incisions. A, Superior intracapsular incision. B, Superior extracapsular incision. C, Temporal scleral (phacoemulsification) incision. D, Temporal limbal (phacoemulsification) incision. E, Temporal clear corneal (phacoemulsification) incision. (From Bruce A, Loughnan M: Anterior eye disease and therapeutics A-Z, ed 2, Sydney, 2011, Churchill Livingstone.)
Strabismus Repair
• The procedure is performed to change the alignment of the eyes, either by loosening or tightening the rectus muscles.
• Misalignments take three forms:
• In esotropia, one or both eyes turn inward.
• In exotropia (a.k.a. divergent squint or walleye), the eyes are deviated outward.
• Amblyopia is impaired or dim vision that is not the result of an obvious defect or change in the eye.
• Recession: reattachment of the medial rectus muscle farther back on the eye
• Resection: surgical shortening of the lateral rectus muscle
Scleral Buckle
• This procedure (Fig. 7.26) involves the placement of a piece of silicone (a semi-hard plastic) around the sclera (white part of the eye), pushing the sclera toward the middle of the eye and replacing a detached retina to its original state.
• The buckle remains in the eye indefinitely unless infection develops after surgery.
• Cryopexy or laser photocoagulation is used to create a scar to seal the tear in the retina.
• Sometimes vitrectomy (see below) is performed in conjuction with the scleral buckle procedure.
Vitrectomy
• An incision is made through the pars plana layer, one of the three layers of the eye near the point where iris and sclera join.
• The main purpose of the vitreous humor, the gel found in the posterior chamber, is to maintain sufficient pressure in the eye to keep the eyeball from collapsing.
• The instrument used to cut and aspirate the vitreous humor is called an ocutome.
• Intraocular gases, mixed with sterile air, are used to flattened the detached retina and keep it attached while healing takes place:
• Sulfur hexafluoride (SF6)
• Per-fluoro-ethane (C2F6)
• Per-fluoro-propane (C3F8)
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