Phototherapeutic Keratectomy

BK can be removed via phototherapeutic keratectomy using an excimer laser, thus avoiding the need for EDTA and scraping the cornea. This obviously requires easy access to an excimer laser, and hence is less commonly used.

CATARACTS

Background

Combined Pars Plana Vitrectomy (PPV) with Cataract Surgery

We often perform PPV at the time of cataract surgery in patients with uveitis when the involvement of the posterior segment is anything but trivial—roughly 1+ vitreous cell or more, which includes many patients with iridocyclitis and almost all with intermediate, diffuse, or posterior uveitis. Our rationale along these lines is anecdotal (as is so often the case in uveitis therapy), but we do observe the following:

• Many patients’ uveitis will be easier to control postoperatively if PPV is performed primarily at the time of cataract surgery/IOL implantation. It postulated that a vitrectomized eye exposes the posterior segment to anterior chamber associated immune deviation, a phenomenon in which antigen presentation in the eye is aberrant, possibly creating an overall downregulation of the inflammatory response. There is no way to know who these patients are in advance, but we find it helpful often enough that the risk/benefit ratio is, in our view, in favor of PPV for patients with vitreous cells.
  
• For patients with vitreitis of any degree, it will definitely be easier to monitor their inflammation postoperatively if the vitreous space is made of liquid, since the cells that one then sees there represent active inflammation much like in the anterior chamber, rather than trapped vitreous debris from remote prior uveitic episodes.
  
• Patients do benefit from the improved media clarity that PPV allows, both from the standpoint of their vision and from our ability to examine their fundus.
  
• Being aphakic as well as vitrectomized has distinct advantages from the standpoint of inflammatory control, since it is almost always easier to control inflammation in eyes that have no lens; a liquid vitreous space; and a single, unicameral chamber. For this reason, we perform PPV and leave an open posterior capsule for all patients whom we are rendering aphakic out of concern for disease control.
  
• In general, 23 or 25 gauge PPV is well suited to this combined cataract surgery/PPV. Our approach is to place the 23 or 25 gauge cannulas before beginning the phacoemulsification. With the lens removed, one can perform a core PPV before or after placing the IOL. Certainly, PPV is easier to perform under aphakic optics, but the sequence of phacoemulsification-PPV-IOL placement can be cumbersome, particularly because we generally make a posterior capsular opening with the vitrector at the end of the case, and this is best done after placing the IOL. Thus, we typically place the IOL before performing the PPV unless the latter promises to be complicated.

Controlling Inflammation Before, During, and After Cataract Surgery

Disease Course

It is critical that ocular inflammation be inactive for a prolonged period prior to performing cataract surgery, and that one minimizes the amount of inflammation that will result from the procedure. For us, a “prolonged period” nearly always means 3 months. Acknowledging that this time frame is somewhat arbitrary, (rigorous studies have not been performed along these lines) it is an amount of time that we feel should be adequate in the great majority of cases, leaving us the least likelihood of dealing with a marked and recalcitrant inflammatory recurrence postoperatively. (Rare exceptions to the 3-month rule, in our view, are the patient with lens-induced uveitis, and those patients in whom cataract surgery is part of a larger procedure—usually a vitrectomy—being performed to improve control of recalcitrant uveitis.)

Gauging Disease Activity

We consider uveitis inactive if there is one cell per anterior chamber high-power field or less. Flare is unavoidable in many patients with longstanding uveitis, and we do not use it to gauge active disease.

Agents Used to Control Inflammation

Topical, injectable, oral and intravenous corticosteroids all have useful roles in perioperative inflammatory control. Other immunosuppressives are often helpful in achieving long-term control in patients for whom we anticipate performing cataract surgery eventually, but we do not generally start these agents specifically for a surgical procedure. Nonsteroidal anti-inflammatory drugs (NSAIDs) are not, in our view, a useful part of the perioperative regimen.

Factors Determining Our Perioperative Regimen

The way in which we combine anti-inflammatory agents varies according to (a) the location of the patient’s uveitis; (b) how severe the inflammation has been, and; (c) how we have been controlling it in the several months prior to surgery. In the simplest scenario, a patient’s inflammation has been quiescent, (i.e., inactive with no corticosteroids and no immunosuppression). Other patients may have been achieving disease control using immunosuppressives only, corticosteroids only, or corticosteroids with immunosuppressives. In the worst-case scenario, a patient’s inflammation is active at the time of surgery. Specific examples dealing with each of these scenarios are described below.

Surgical Considerations

From the technical standpoint, uveitis-related cataract surgery differs very little from surgery for routine cataracts. The items discussed below pertain to phacoemulsification.

Choice of incisions. We generally use clear cornea incisions but find no problems with scleral tunnel incisions, or with the use of cautery.

Intraoperative materials. No special viscoelastics or intraoperative solutions are necessary or advantageous, in our view.

Posterior synechiae and pupil dilation. In general, lens-iris adhesions are easily broken with any blunt instrument (viscoelastic cannula, Sinskey hooks), and a scarred pupil can be dilated by stretching it manually using Kuglen or collar-button hooks, or with iris hooks if necessary. Pupillary sphincterotomies are reasonable to perform. Very extensive lens-iris adhesions may necessitate cutting the iris off of the lens using retinopathy of prematurity scissors, in effect creating a new pupillary margin. We occasionally cut off smaller iris adhesions that we feel are likely to stick to the lens capsule.

IOLs. We have not found any particular IOL to be preferable to others for uveitis-related cataracts, and we place our IOLs in the capsular bag. Some authors have suggested that ciliary sulcus IOL placement may be helpful in preventing posterior synechiae formation; we have found the disadvantages of this approach to outweigh this possible benefit. As noted above, we avoid IOLs altogether in certain scenarios.

Examples of Regimens to Control Perioperative Inflammation

As noted above, our choice of preoperative, intraoperative, and postoperative anti-inflammatory regimens depends on the location of the patients’ uveitis, how severe a patient’s inflammation has been, and how we have been controlling it prior to booking the surgery. For the purposes of this discussion, we will assume that surgery is booked 3 months prior to the date it is performed. In all scenarios, the inflammation should be inactive at the time of booking. We then consider ways to prevent the inflammation from recurring between the time surgery is booked and the time it is performed, (recurrence of inflammation in this 3-month period necessitates postponing the surgery), and the optimal means of minimizing postoperative inflammation.

Quiescent inflammation

Patients whose inflammation has been quiescent (inactive and requiring no treatment) or controlled with immunosuppressive drugs and no corticosteroids for several months. This is the simplest scenario.

Anterior uveitis, planning phacoemulsification only

Preoperatively: we start topical corticosteroids four times per day to prevent an inflammatory recurrence after we book the case. One week prior to the surgery, we perform an intravitreous triamcinolone 2 mg injection. Topical corticosteroids are used hourly on the day prior to the surgery. This approach greatly simplifies the intraoperative and postoperative regimens: no systemic corticosteroids are needed at any point, and topical corticosteroids four times per day are sufficient for postoperative disease control, with a tapering routine quite like a typical phacoemulsification in a nonuveitic patient. Cycloplegic eyedrops are not necessary.

Intermediate, Diffuse, or Posterior Uveitis, Planning phacoemulsification Combined with PPV

Preoperatively: any time between 12 and 6 weeks, we perform a periocular triamcinolone 20 mg injection, and 1 to 2 weeks preoperatively we repeat this. Topical corticosteroids are used hourly on the day prior to the surgery. Intraoperatively: we inject intravitreous triamcinolone 2 to 4 mg at the close of the procedure. Postoperatively: topical corticosteroids four times per day are sufficient, with a taper based on clinical response. Cycloplegics are not necessary.

Controlled inflammation

Patients whose inflammation has been controlled with corticosteroids (with or without immunosuppressive drugs in addition) for several months.

Anterior uveitis, planning phacoemulsification only

Preoperatively: we administer a periocular triamcinolone 20 mg injection when booking the case, repeating this 6 weeks preoperatively. One week preoperatively, we perform an intravitreous triamcinolone 2 mg injection. Oral corticosteroids equivalent to prednisone 1 mg/kg/day should be started 3 days before the surgery. Topical corticosteroids are used hourly the day before the procedure. Intraoperatively: methylprednisolone 1,000 mg is given intravenously during the procedure (dexamethasone 200 mg is a reasonable alternative). Postoperatively: topical corticosteroids four times per day are used, to be tapered as tolerated. Oral corticosteroids need not be taken on the day of surgery but are resumed the following day for 3 more days, and can then be discontinued without tapering. Wegenerally use atropine 1% two times per day for 1 week postoperatively.

Intermediate, Diffuse, or Posterior Uveitis, Planning phacoemulsification Combined with PPV

Special Cases

Patients Whose Inflammation is Active at the Time of Surgery

This is another scenario that one should avoid whenever possible. The typical case is a patient with lens-induced uveitis in whom the control of inflammation and IOP will be impossible without lens removal. We strongly recommend combined phacoemulsification/vitrectomy (anterior or posterior) in these cases, and plan to leave the patient with an aphakic and unicameral eye. One usually books the case at most a few days in advance, and oral corticosteroids equivalent to prednisone 1 mg/kg/day, along with topical corticosteroids hourly, are started as far as possible in advance of the case. Ideally, these patients receive methylprednisolone 1,000 mg IV starting 1 day preoperatively, and again intraoperatively and if possible 1 day postoperatively as well. Intravitreous triamcinolone 4 mg is injected at the close of the case. Postoperatively: oral corticosteroids are started following the final IV methylprednisolone dose, and are continued for an additional 2 weeks before being tapered off over an additional 2 weeks. Hourly topical corticosteroids and atropine 1% two times per day are used for at least 2 weeks postoperatively as well.

Patient with Iris Bombe and Pupillary Block with Intractably High IOP

These patients are usually actively inflamed or have only recently had their inflammation controlled, and we handle them quite like patients with lens-induced uveitis; our approach is quite similar to that described above. As with lens-induced uveitis, we find great benefit to combining phacoemulsification and PPV in this scenario, planning to leave the patient with an aphakic, unicameral eye. We prefer this approach to laser iridotomy or peripheral iridectomy (PI), since these latter options frequently result in more surgical manipulation and often more inflammation ultimately than a single, decisive initial surgical procedure. An IOL can be placed once inflammation has been controlled for 3 months.

Cataract Surgery in Patients with Scleritis

As with patients with uveitis, we require 3 months of disease control before performing cataract surgery in scleritis patients. At the time we book the case, we inject periocular triamcinolone 4 mg in each quadrant of the eye planned for surgery, repeating this 6 weeks preoperatively. Approximately 3 days prior to surgery, we start oral corticosteroids equivalent to 1 mg/kg/day, and topical corticosteroids are taken hourly the day before surgery. Methylprednisolone 1,000 mg IV is given during surgery. The surgery performed is quite like that performed for uveitis patients. Postoperatively, oral corticosteroids are taken for an additional 1 to 2 weeks before being tapered.

Some patients are “fibrin membrane formers” and this finding represents among the worst-case postoperative scenarios in uveitis-related cataract surgery. Typically, the reaction begins 2 to 5 days following the procedure and increases daily, as if feeding on itself. Daily examinations show strands of clear fibrin that gradually transforms into a gray membrane that extent to the wound, across the pupil, or may encase the IOL. Fibrin membranes were far more common before intravitreal corticosteroid injection became common practice. If we see a patient who we believe is developing a fibrin membrane, the options are

Corticosteroid-induced IOP elevation merits special mention because it is commonly encountered in uveitis practice. A number of studies suggest that roughly one third of patients will develop this complication some time after 2 weeks of corticosteroid use. Another third will develop it at some point after months to years of corticosteroid use, and almost another third can use corticosteroids with impunity from the IOP standpoint, never developing increased IOP. A very small number (a few percent) of patients will develop severe IOP elevation after a very short exposure (days) to corticosteroids. IOP elevation is the most notable complication of periocular and intraocular corticosteroid injections, and in the former cases, we occasionally remove injected corticosteroid deposits from the subtenon or subconjunctival space. Intraocular corticosteroids will usually dissolve sufficiently soon; hence, removal is not necessary. Corticosteroid-induced IOP elevation will almost always normalize when the incinting corticosteroids dissolve, are stopped, or are removed. However, IOP elevation is a very frequent complication of the intraocular fluocinolone implant, and we counsel these patients accordingly when discussing this intervention.

General Principles

Perioperative inflammatory control is essential, and we apply the same considerations to glaucoma surgery as we do to cataract surgery: uveitis should be inactive for 3 months prior to performing glaucoma surgery. This is generally achievable for most patients, acknowledging that glaucoma surgery is not always elective, and some patients require IOP lowering much sooner. In all cases, the timing of surgery is dependent on interplay between need for acute pressure lowering, given the glaucoma status, the amount of IOP elevation, and the likelihood of surgical success given the extent of inflammation. The most obvious examples of an exception to the “3 month rule” are those with poorly controlled uveitis who develop seclusio pupillae and subsequent iris bombé with total angle closure, and often present with active uveitis and very high IOP. In this setting, there is often little alternative to achieving immediate control of the uveitis with corticosteroids and, if the IOP cannot be controlled medically, proceeding with glaucoma surgery within a matter of days to weeks. Other exceptions present themselves occasionally, but in all cases, one needs to acknowledge—and discuss with the patient—that the likelihood of a postoperative inflammatory exacerbation increases the sooner one proceeds after controlling inflammation; we plan the perioperative regimen accordingly.

Measures for perioperative inflammatory control are the same as those outlined above for phacoemulsification. We make extensive use of periocular, topical, intraocular, and systemic corticosteroids to minimize postoperative inflammation. In administering periocular corticosteroids to patients in whom we plan glaucoma surgery, we try to avoid the superior quadrants, since corticosteroid injections can cause scarring of the conjunctiva, which complicates the surgical procedure. These injections are best given transseptally along the orbital floor, or transconjunctivally in the inferior subtenon space.

Hypotony is a common complication of glaucoma surgery in the setting of uveitis, presumably because these patients’ eyes produce aqueous humor irregularly, and often insufficiently. Thus, one is commonly faced with a patient whose eye or eyes have scarred trabecular meshwork and drainage architecture, yet produce low amounts of aqueous humor. The surgical plan and postoperative expectations need to be modified accordingly, to include the possibilities that filtering or shunt procedures may need to be revised to minimize postoperative hypotony.

The surgical technique for glaucoma surgical procedures in uveitis patients is the same as for patients without uveitis. No modifications of the surgical procedures are needed. As we have noted elsewhere, however, one needs to pay considerable attention to the perioperative regimen to minimize the likelihood of an inflammatory response postoperatively.

Surgical Therapies

For Angle Closure Glaucoma

Our decision-making in this setting depends on the extent of cataract present in the eye, and whether the eye is inflamed. (As noted above, an occasional dilemma in the management of uveitic closed angle glaucoma is the patient whose eye is or was very recently inflamed and now presents with seclusio pupillae and iris bombé, often with very high, recalcitrant IOP.)

If a fair amount of cataract is present, we generally opt for phacoemulsification, and if the uveitis is or was recently active—as in the setting of seclusio pupillae and iris bombé—we leave the eye aphakic and perform PPV at the same time. The perioperative management of this scenario is explained above in Sections 7 and 8 of the cataract surgery portion of this chapter.

Usually, IOP will improve if the angle can be reformed, even if iris bombé was present. Many patients with uveitis will, however, eventually require filtering or tube shunt surgery (see below) at a later date.

Open Angle Glaucoma

When medical therapy is inadequate for the treatment of uveitic open angle glaucoma, we face a choice between trabeculectomy and tube shunt placement. There are few hard and fast rules in this common scenario, although without question most specialists are leaning increasingly toward tube shunt procedures in the setting of uveitic glaucoma.

Trabeculectomy. We do nevertheless favor trabeculectomy in patients who (a) are not children or young adults and thus are more likely to sustain a bleb without extensive scarring, (b) have excellent control of their inflammation and will probably maintain good control in the future (e.g., patients on very effective immunosuppressive regimens or who have a fluocinolone intraocular implant in the affected eye), (c) have an overall level of understanding and emotional resilience to undergo postoperative revisions if necessary, and (d) require very low IOPs postoperatively (11 or less). We include mitomycin C in all cases of trabeculectomy in uveitis patients, and while this has the minor disadvantage of some limited toxic exposure, it has the advantage of avoiding the placement of hardware on the eye, thus avoiding the risk of hardware-related complications like exposure and infection. Our perioperative regimen for trabeculectomy is the same as for phacoemulsification, as described above in this chapter.