Ординатура / Офтальмология / Английские материалы / The Eye Book A Complete Guide to Eye Disorders and Health_Cassel, Billig, Randall_2001

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thing the night before surgery, from midnight onward. (This is a routine precaution before any type of anesthesia is given; it can vary greatly depending on the surgeon, the surgical center, and the specific anesthesia that will be used.) You’ll probably be told to continue taking any medicines you normally take on a daily basis (but on the day of surgery to swallow them with only small sips of water). Note: Bring a list of your medications, and when you last took them, to the surgical center before the operation. Your surgeon may also want you to take antibiotic eye drops before the procedure.

If you take insulin, be sure to check with your internist, family doctor, or endocrinologist about the doses you’ll need on the morning of surgery. If you usually take prophylactic doses of oral antibiotics—to protect a damaged heart valve, for instance—before dental procedures, it’s a good idea to check with your medical doctor about taking these antibiotics before cataract surgery.

Aspirin and Coumadin are both known to interfere with blood clotting. Therefore, most doctors recommend that all aspirin use be stopped at least two weeks before cataract surgery because of the risk of intraocular bleeding or hemorrhage during retrobulbar anesthesia (see below). However, this should be done only with the consent of the internist, family doctor, or specialist who put you on aspirin in the first place. Stopping Coumadin before cataract surgery is a trickier prospect, because interrupting it for even a short period of time can put some patients at serious risk for a stroke. (In this case you and your eye surgeon, after a thorough discussion of

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the risks of being anticoagulated at the time of cataract surgery, may decide to continue the Coumadin and go ahead with the operation.)

The Procedure Itself

Your surgery may be performed at a hospital, at an outpatient surgicenter, or in a surgical facility connected to your doctor’s office. Wherever it is, you’ll probably be asked to arrive early, sometimes as much as an hour and a half before the actual scheduled time of the operation, to allow plenty of time for preoperative preparation. (This usually includes a review of the presurgical testing results, interviews by nursing and anesthesia staff, and eye drops.) The regimen of preoperative eye drops varies, but it usually includes dilating drops (such as Mydriacyl and NeoSynephrine) and may also include an antibiotic and a corticosteroid or nonsteroidal anti-in- flammatory medication such as flurbiprofen (Ocufen). Anesthetic eye drops are usually applied to both eyes— to numb the eye that will be operated on, and to make the other eye more comfortable during surgery.

Patients often ask if they’ll need to remove their clothes for the procedure. A reasonable question; the answer varies depending on the surgical facility. Even if you do get to keep your own clothes on, you’ll wear a surgical gown or covering during the procedure. Human nature being what it is, it’s a good idea to keep such personal articles as watches, rings, money, and wallets to a

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minimum (and preferably to leave them locked up at home).

Note: A quick trip to the bathroom before surgery can be very important and help avoid an embarrassing situation. (But even if you take this precaution and still have to go, don’t worry: if necessary, you can use a urinal or bedpan during the surgery.)

In the operating room, your eye and the region around it will be cleaned with an antibacterial and antiseptic solution. Sterile drapes and sheets will also be laid over and around the eye to lower the risk of infection. Oxygen is usually provided to the patient through a nose tube because it can be hard to breathe under the drapes. At most centers, patients’ blood pressure, blood-oxygen levels, and cardiac rhythm are also monitored throughout the procedure.

We should note again that there is considerable variability among surgeons and centers regarding the procedures on the day of cataract surgery. But in general, all patients receive some degree of sedation, followed by injections of local anesthesia around and behind the eye. A local injection to prevent the eye from closing may also be given. As mentioned previously, some patients may receive only topical anesthesia. Note: The medication used is usually lidocaine or something similar—just like the lidocaine your dentist uses. So if you’ve ever had any problems with local anesthesia in the dentist’s chair, be sure to tell your surgeon!

Retrobulbar anesthesia, a local injection of anesthetic

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behind the eyeball, works by blocking the nerves leading to the muscles that control the movement of the eyeball and eyelid. This injection is performed with a long, thin needle that is usually inserted through the lower eyelid to a point behind the eyeball where the ocular nerves and muscles nestle closely together. A retrobulbar injection is not without risk. Your doctor guides the needle without being able to see the structures behind the eye such as blood vessels, nerves, muscles, and—most impor- tant—the eyeball itself. Although eye surgeons and anesthesiologists perform this injection with great care and complications are rare, they do occur and can include nicking a blood vessel (causing a retrobulbar hemorrhage), perforating the eyeball, or injuring the optic nerve. These complications can occur in even the most experienced hands and usually require postponing the planned cataract surgery until a later date. But the vast majority of these injections are performed each year without any complications at all. (However, because the risk of these complications, small though it may be, is present, some surgeons advocate other anesthesia and surgical techniques that are associated with less risk. The indications, safety, and effectiveness of these newer techniques are currently being assessed.)

After retrobulbar anesthesia, pressure is applied to the eyeball, either manually, by the doctor’s finger, or using a special device or weight over the eyeball. This pressure on the eyeball serves two purposes. First, it encourages any bleeding—if a blood vessel was nicked or severed during the retrobulbar injection, for instance—to stop,

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and it maximizes clotting. Second, pressure on the eyeball decreases the pressure within the eye by displacing fluid from the eyeball into the systemic circulation. (And lower intraocular pressure decreases the risk of surgical complications.)

The atmosphere in the operating room probably won’t be nearly as intense as it’s usually portrayed in the movies and on TV; many patients are pleasantly surprised to find that the staff is congenial, with a warm, comforting attitude. Many patients worry that they won’t be able to keep their eye open throughout the whole operation—that they’ll accidentally blink and derail the procedure. As the old slogan goes, “Leave the driving to us.” We’ll keep your eyelids open, using a lid speculum or specially designed retraction device.

Now it’s time to remove that cataract. First, an incision must be made into the eyeball. Most incisions are placed somewhere in the upper half of the eyeball, relatively near where the cornea meets the sclera (the “white” of the eye); this area is known as the limbus of the eye. The length and specific placement of the incision depend on which technique the surgeon will be using to remove your cataract. Smaller surgical incisions speed up recovery time; they’re also less likely to cause postoperative astigmatism, an abnormal curvature of the corneal surface that is created as the wound heals. But in intracapsular and extracapsular cataract surgery, where the lens of the eye is removed in one piece, the surgical incision must be large, as long as 10 to 12 millimeters, or about half an inch.

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Intracapsular cataract extraction (ICCE), very popular many years ago before modern microsurgical techniques were developed, is rarely performed these days. In an ICCE the lens is removed intact, complete with the surrounding capsular lens bag. Extracapsular cataract extractions (ECCE) involve opening the capsular lens bag and removing the lens located within it. The inner lens is extracted from the eye in one piece. A surgeon may choose this technique if he or she is more skilled in this procedure than in other methods of cataract surgery. Also, this technique is often reserved for very dense and firm cataracts that would be difficult to break up with phacoemulsification.

In phacoemulsification cataract extraction, incisions can be much smaller—approximately 3 millimeters, or one-eighth of an inch. In this very popular form of cataract surgery, the cataractous lens is broken up inside the eye with ultrasound waves emanating from a specially designed surgical instrument inserted through the incision. This instrument then vacuums up these small lens fragments as they’re broken up. (The use of lasers for cataract surgery will be discussed later. At this point, lasers are not used to remove cataracts from the eye. Since a cataract is a solid structure, it must be removed, either in one piece or in fragments. None of the above techniques involves the use of a laser, which burns or cuts through an object or tissue.)

With extracapsular extraction and phacoemulsification, after the cataract is removed from the eye, it’s often necessary to use an irrigation and aspiration technique

Image not available.

Fig. 7.5. Phacoemulsification

Image not available.

Fig. 7.6. Incisions for extracapsular extraction and phacoemulsification

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to clean up any leftover fragments of the cataract. Although this technique can be performed manually, most surgeons prefer to use an automated system.

Now it’s time to insert the intraocular implant lens. At this point the incision is either large (approximately 10 millimeters) or small. Different implant lenses require different-sized incisions to be made in the eye, ranging from approximately 3 millimeters for foldable lenses to 7 millimeters for larger-diameter solid plastic polymer implants. Depending on the surgeon’s choice of implant lens, then, the opening may need to be enlarged for its insertion. (Once again, the style and size of the implant lens chosen for each patient vary, depending on a multitude of factors.)

Closure of the opening, or wound, has become a highly publicized issue in cataract surgery advertisements. Advertisements for “one-stitch” or “no-stitch” surgery, popularized by surgeons as the most modern, state-of-the-art approach to cataract surgery, imply that the eye surgeons who use these techniques are a cut above all the rest. The truth is that the majority of eye surgeons today perform phacoemulsification and onestitch or no-stitch surgery. What’s the difference between one-stitch and no-stitch? Well, think about why most men wear belts: they probably don’t actually need a belt to keep their pants up, but they feel more secure knowing it’s there. Most small incision wounds don’t need to be sutured, but many surgeons put one suture in anyway just to help them sleep better at night. Smaller incisions