Cataracts occur commonly in patients with uveitis for at least two reasons. First, and most importantly, uveitis itself promotes cataract formation. In fact, patients who have more severe or more frequent bouts of inflammation usually develop cataract more rapidly than patients with mild or infrequent attacks of uveitis. Second, the medications used most frequently to treat uveitis, corticosteroids, themselves promote lens opacification. Corticosteroids are still used, however, both because they are effective and because the untoward effects of uncontrolled uveitis far outweigh the complications of corticosteroid therapy. Therefore, premature cataract develops in most uveitis patients despite good inflammatory control. Fortunately, modern cataract surgery is safe even in those patients with a long history of intraocular inflammation. Cataract removal is more challenging in patients with uveitis, however, and requires careful planning before, during, and after surgery.
Patient Selection and Timing of Surgery
There are many causes of uveitis, and patients with certain forms of inflammation respond better to cataract surgery than others. Patients with Fuchs’ heterochromic uveitis, pars planitis, and Behcet syndrome, for example, usually respond particularly well to cataract surgery, in that there tends to be relatively little postoperative inflammation and little or no tendency for anterior or posterior synechiae formation. These patients can usually have a primary IOL implantation without difficulty, therefore, and will often require relatively little additional corticosteroid medication perioperatively. Other disorders, in contrast, such as juvenile idiopathic arthritis (also known as juvenile rheumatoid arthritis and juvenile chronic arthritis), severe HLA-B27-associated uveitis, and granulomatous diseases such as sarcoidosis and Vogt-Koyanagi-Harada disease, tend to dispose eyes to more frequent moderate to severe postoperative inflammation and complications related to synechiae formation. Consequently, patients with these forms of uveitis may not always be able to have an IOL implanted once their cataracts are removed. Similarly, for any given patient, it is important to know how difficult it has been to control his or her uveitis. Patients with more recurrences, or those who tend to have episodes of uveitis that are more severe, will probably have greater difficulty with surgery. Conversely, patients who have had only one mild attack of uveitis tend to do better with surgery. In general, cataract surgery in patients with anterior uveitis is more challenging than in patients with intermediate or posterior uveitis.
Perhaps the most important predictor of successful cataract surgery in patients with intraocular inflammation is the meticulous control of preoperative inflammation. Patients with active or poorly controlled uveitis should not undergo cataract surgery. The one exception to this cardinal rule is when the cataract itself is the cause of the uveitis, as in traumatic or phacolytic cataract. Lens-induced uveitis is the one instance where absolute control of the intraocular inflammation is not required prior to cataract removal.
Most authorities agree that the longer intraocular inflammation is controlled prior to surgery, the better. Moreover, most view 3 months as the minimal amount of time that a patient should be without inflammation prior to surgery. Longer periods of quiescence s hould be allotted for eyes that have had more recurrences, for eyes with more severe forms of uveitis, and for eyes with anterior granulomatous features or synechiae formation.
It is often difficult to predict what the post-surgical visual outcome will be in patients with uveitis. Occasionally, co-existing ocular abnormalities that limit vision prior to surgery will also limit vision following surgery. Such limitations notwithstanding, however, it is important to try to identify factors in patients that might make cataract surgery and/or the recovery more difficult.
In addition to the type of uveitis, the following factors can influence surgical outcome:
While none of these factors necessarily prohibits any given patient from having cataract surgery, both the patient and his or her surgeon should be aware that they can make surgery more difficult and may slow or even limit the recovery of vision.
Besides the patient’s visual needs, cataract surgery is occasionally indicated to improve visualization of the fundus in patients with uveitis. This is particularly true when the inflammation involves the posterior pole, and the treating ophthalmologist needs to be able to examine the fundus carefully to follow disease activity and/or the efficacy of therapy. In these circumstances, cataract may need to be removed even when the vision is not expected to improve markedly following the procedure.
Every possible attempt should be made to identify a cause for the uveitis prior to cataract surgery. As mentioned above, certain diseases tend to respond well to surgery, whereas other disorders pose more challenges both during and after the procedure. Establishing the diagnosis helps predict the patient’s response to surgery. It is also important to identify those inflammatory disorders that are associated with systemic diseases. It does relatively little good, for example, to remove a patient’s cataract if he or she is suffering from a potentially fatal and unrecognized systemic illness. For these reasons, uveitis specialists will go to great lengths to identify the cause of inflammation in every patient.
Once every attempt has been made to establish the cause for the uveitis, the visual potential of the eye with cataract should be assessed. It is beneficial, for example, to know that the eye had a normal visual acuity prior to the development of the cataract. An eye that has had amblyopia since childhood will have a limited visual outcome even after the most successful cataract surgery. It is also important, whenever possible, to rule out co-existing retinal or optic nerve damage that might limit visual recovery, as mentioned above. The optic nerve function can be examined with a swinging flashlight to test for an afferent pupillary defect or with color vision testing. A potential acuity meter (PAM) can be used to estimate the visual potential of the macula. When the cataract is so dense that it obscures the fundus, B-scan ultrasound can be used to rule out occult retinal detachment or intraocular tumors.
Once the intraocular inflammation has been controlled for 3 to 6 months with corticosteroids or non-corticosteroid immunosuppressive agents, most patients with uveitis may undergo cataract surgery if not otherwise contraindicated. In addition to counseling about the risks, benefits, and alternatives of surgery, the ophthalmologist and the patient should have a frank discussion, noting that
In general, the same surgical approach can be used for patients with uveitis as would be used for patients without uveitis. Most patients with uveitis can undergo clear corneal incision cataract surgery using topical anesthesia. There are some differences between patients with and without uveitis, however, and these should be noted while planning for surgery.
Patients with uveitis often tend to develop synechiae. Two types of synechiae may form. First and most common are posterior synechiae, which can cause the pupil to be both immobile and irregular. Posterior synechiae may also produce glaucoma by way of pupillary block. Second, and less common, are anterior synechiae, which both damage and occlude the angle, limiting aqueous outflow. While anterior synechiae should seldom be lysed, posterior synechiae in fact need to be released in order to remove the cataract. Opening posterior synechiae is usually best performed with blunt dissection using either a cannula filled with viscoelastic or a dialysis spatula. Additional viscoelastic can be injected under the iris to help release adhesions and to protect the anterior lens capsule. Once the iris is freed, it should then be stretched using iris retractors to allow adequate visualization of the cataract and to permit anterior capsulotomy. Occasionally, devices such as iris hooks are required to maintain the configuration of the pupil during surgery. Occasionally, sphincterotomies are required. Thorough cortical cleanup is particularly important in these inflammation-prone eyes.
Once the cataract is removed, the surgeon must decide whether the patient is a good candidate to receive an IOL implant. As mentioned, patients with Fuchs’ heterochromic uveitis, pars planitis, and Behcet syndrome all tend to do well with implants. In contrast, patients with granulomatous disease, such as sarcoidosis or Vogt-Koyanagi-Harada’s disease, and children with severe forms of uveitis, such as juvenile idiopathic arthritis, tend to do less well. Similarly, special care should also be taken with monocular patients, with very young patients, with patients who may have difficulty complying with intensive postoperative medication schedules, and with patients who have had a complicated cataract surgery in the fellow eye. If a lens implant is to be used, either a PMMA or an acrylic lens can be placed safely. First-generation silicone lenses should be avoided in patients with uveitis, however, as they are less biocompatible. There are few published studies of second-generation silicone in uveitic eyes, although this material appears to be very biocompatible.
Once the decision has been made to place an IOL and the lens type has been chosen, positioning the lens becomes the next decision. Most patients with uveitis and cataract can have their IOLs placed safely in the capsular bag, just as would be done for non-uveitis patients with cataract. Some authorities suggest, however, that the artificial lens may be better off in the ciliary sulcus, so as to prevent the formation of synechiae between the iris and the capsular bag following surgery. In fact, this approach may be indicated in those patients who are prone to form such adhesions. Once placed, the lens should be well centered, and care should be taken to avoid capture of the optic by either the lens capsule or the iris. Iris-mounted, anterior chamber, and scleral-fixated IOLs should be avoided in patients with uveitis.
Following cataract surgery in patients with uveitis, the topical and oral corticosteroids that were started prior to surgery should be tapered very slowly. This usually takes anywhere from 3 to 6 weeks but may be even longer in patients with severe or frequently recurrent uveitis. Some patients may require additional immunosuppressive agents, such as methotrexate, azathioprine, or cyclosporine, to control their postoperative inflammation, particularly if these agents were required to control their uveitis prior to surgery. In general, if patients were on long-term immunosuppressive therapy prior to surgery, then this should be continued following the procedure.
Most patients with a history of intraocular inflammation and cataract respond well to cataract surgery. Patients with a history of uveitis often have more postoperative inflammation than average. However, one should not forget that two potential causes of excessive postoperative inflammation are infection and retained lens material. The latter may require secondary removal if the inflammation or intraocular pressure cannot be controlled. Potential infection must be evaluated by culture and then treated with appropriate intraocular antibiotics.
Following surgery, the intraocular pressure may either be elevated or decreased. Elevated intraocular pressure can usually be controlled with pressure-lowering medication, but may sometimes require glaucoma surgery in very severe and refractory cases. Problems with low pressure after surgery may be due either to an increase in the amount of inflammation, to a wound leak, to a cyclodialysis cleft, or to choroidal detachments. Whereas hypotony due to inflammation usually responds to anti-inflammatory medications, such as corticosteroids, wound leaks and cyclodialysis clefts often require additional surgery. Choroidal detachments may settle spontaneously or require drainage.
One of the more common complications for patients with uveitis is cystoid macula edema (CME). CME appears to be more common in patients who have an exaggerated inflammatory reaction following surgery, especially when there is moderate to severe vitreous inflammation. It will often respond to topical corticosteroid or nonsteroidal anti-inflammatory drops, but in those patients who do not respond to topical corticosteroids, a periocular corticosteroid injection of triamcinolone acetonide, 40 mg, may be indicated. In some patients, CME is refractory and results in permanent visual impairment.
Cataract is a common complication of uveitis. Fortunately, however, modern cataract surgery can restore good vision in most patients. While patients with uveitis require special preparation and planning, appropriate patient selection, meticulous suppression of preoperative inflammation, careful surgical technique, and prompt management of complications can restore good vision.