What can patients expect from cataract surgery?
ABSTRACTCataract surgery has evolved into an outpatient procedure that requires minimal anesthesia and significantly improves visual function for about 90% of patients. With the help of their primary care physician and ophthalmologist, patients can decide when cataract surgery is appropriate for them. In addition, patients may have a choice about the type of synthetic lens implant that fits their visual needs.
KEY POINTS
- Known risk factors for cataract include age, family history, smoking, sunlight exposure, diabetes, trauma, and corticosteroid use.
- Patients taking aspirin or other anticoagulant drugs do not need to change their regimen before undergoing cataract extraction. However, measures of control such as the international normalized ratio should be within the therapeutic range.
- Any patient who develops pain and decreased vision 2 to 5 days after surgery requires an immediate evaluation by an ophthalmologist.
- Improvements in cataract surgery include topical anesthesia and phacoemulsification—dissolving or emulsifying the lens through a small incision.
- New multifocal intraocular lenses offer refractive correction and give some patients the ability to see both close up and at a distance without glasses after cataract surgery.
Topical anesthesia now used most often
Topical anesthesia with eyedrops is now the most frequently used type of anesthesia for cataract surgery, specifically in cooperative patients undergoing phacoemulsification (see below). The advantages: fewer vision-threatening complications occur than with retrobulbar or peribulbar injections.16–21 Most patients need less sedation and therefore have fewer systemic postoperative problems such as nausea and vomiting. Also, topical anesthesia does not affect vision and does not cause akinesia (temporary paralysis) of the eye, so many patients have useful and improved vision immediately after surgery.
However, the patient must be able to cooperate during the procedure. Another disadvantage of topical anesthesia is greater patient awareness of surgical manipulation, because the area of local anesthetic effect is smaller than with retrobulbar block. In addition, it does not provide akinesia, so the surgeon has less control of the operating environment.
Rarely, general anesthesia may be appropriate in patients who cannot cooperate because of advanced age, poor mental status, or severe claustrophobia.
CURRENT SURGICAL TECHNIQUES
The three main techniques for cataract extraction today are extracapsular extraction, phacoemulsification, and intracapsular extraction.
Extracapsular cataract extraction involves removing the opacified lens but leaving the capsule of the lens and its zonular attachments intact. The capsular bag then provides a scaffold for implantation of a synthetic lens.
One method of extracapsular cataract extraction involves removing the entire nucleus through an 11-mm incision at the corneal-scleral junction. This procedure is used more often for dense, more advanced cataracts.
Phacoemulsification is currently the most commonly used procedure for cataract extraction in the United States.22–24 This is a less-invasive version of extracapsular cataract extraction, developed by Kelman22 in 1967, in which the lens nucleus is emulsified within its capsule using an ultrasonic probe inserted through a small (3-mm) incision.
The advantages of phacoemulsification compared with regular extracapsular extraction are that the incision is smaller, the rates of intraoperative complications such as vitreous loss and iris prolapse are lower, the procedure time is shorter, and the time to visual recovery is faster. As with the other extracapsular approach, the capsular bag is maintained, allowing for easy placement of a synthetic lens implant.
Intracapsular cataract extraction is the removal of the entire lens including the capsule, after which the patient must wear special (ie, aphakic) eyeglasses. This procedure is no longer used in developed countries except in rare cases such as a partly dislocated lens, although it is still used in the developing world. It has a high rate of intraoperative and postoperative complications.21
POSTOPERATIVE COMPLICATIONS
The most feared complication of cataract surgery is intraocular infection, or endophthalmitis. Acute endophthalmitis generally develops 2 to 5 days after surgery and can cause severe, permanent vision loss. Fortunately, the frequency of endophthalmitis is low (0.08% to 0.1%). However, any patient who develops pain and decreased vision 2 to 5 days after cataract surgery should be evaluated immediately by an ophthalmologist.25–27
The most common postoperative complication of extracapsular cataract extraction is posterior capsular opacification. This results from proliferation of residual lens epithelial cells within the lens capsule, causing opacification and decreased visual acuity. Posterior capsular opacification occurs after approximately 25% of surgeries within 5 years after surgery. The risk is higher in younger patients (because of greater activity of lens epithelial cells in younger people) and with certain intraocular lens designs.28,29 Treatment consists of laser capsulotomy using a neodymium-yttrium-aluminum-garnet (Nd-YAG) laser, a simple office procedure.
OUTCOMES
Outcomes of cataract surgery are generally very good: 90% of patients achieve a “best-corrected vision” (ie, vision corrected with glasses or contact lenses) of 20/40 or better. This includes patients with diabetes and glaucoma. If patients with these conditions are excluded and only those with otherwise-healthy eyes are analyzed, the percentage of patients gaining 20/40 or better vision increases to 95%.30–33
Cataract surgery in the very elderly
The results of cataract surgery in people over age 85 are not quite as good: only 85% have a significant improvement in vision. This lower rate is probably due to unrecognized comorbidity.
Cataract surgery in diabetic patients
Diabetic patients undergoing cataract extraction require special consideration. Visual acuity after surgery may not be as good in patients with advanced diabetic retinopathy as it is in those with mild retinopathy.31–33 In particular, macular edema is likely to persist after cataract surgery and affect final visual acuity.34
If the cataract does not prevent it, pre-treatment of diabetic eye disease is appropriate. Adjunctive treatment such as intravitreal injection of triamcinolone acetate at the time of surgery may also be useful, as may topical nonsteroidal anti-inflammatory drugs.
