Surgical Management of Uveitic Glaucoma
Surgical Assessment of Uveitic Glaucoma
Glaucoma surgery in patients with uveitis is not easy. First, uveitis reduces the success rate of glaucoma surgery. Not only are eyes with uveitis more likely to scar and fail glaucoma outflow surgery, but they are also more prone to hypotony. Second, glaucoma surgery itself can exacerbate uveitis. Not only can surgical trauma cause a flare of inflammation, but it can also lead to initiation or worsening of cystoid macular edema. Therefore, great care must be taken in planning and timing surgical intervention to minimize risks and maximize the chance of success.
Mechanisms of Glaucoma in Uveitis
- Closed Angle
- Peripheral anterior synechiae
- Pupillary block
- Neovascular glaucoma
- Open Angle
- Steroid response
- Clogging of TM by cells, fibrin, inflammatory debris
- Chronic TM damage and scarring of outflow channels
As mentioned above, eyes with chronic or recurrent uveitis are more prone to hypotony after glaucoma surgery. It is commonly known that actively inflamed eyes hyposecrete aqueous acutely. However, it is equally
important to realize that repeated bouts of ciliary body inflammation can lead to profound atrophy of the ciliary processes and chronic aqueous hyposecretion. This can lead to a dreaded “high-low” syndrome of uncontrolled high intraocular pressure (IOP) prior to glaucoma surgery, intractable hypotony after glaucoma surgery, and again uncontrolled IOP after outflow surgery is reversed.
When possible, surgical intervention should be delayed until inflammation is absent, or at least minimized. If necessary, oral acetazolamide can be useful to help delay surgical intervention. In some cases without severe optic nerve damage, it may be safer to observe elevated IOP for several weeks while control of acute inflammation is achieved than to intervene in an inflamed eye.
In the days leading up to surgery, it is important to maximize anti-inflammatory therapy. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) may be added because they will not exacerbate IOP. If a significant steroid response component is not present, topical, and sometimes oral, corticosteroids should be maximized.
If the uveitis is related to herpes virus, prophylaxis with full-treatment dose of oral antivirals surgery (ie, acyclovir 400 mg 5 times daily for her-pes simplex virus or 800 mg 5 times daily for herpes zoster) should be started 1 to 3 days prior to surgery and continued as long as the patient is on elevated steroid dosing.
When operating in an eye with uveitis, it is important to minimize intraocular manipulation by operating efficiently, entering the eye as few times as possible, avoiding the iris and uvea, and taking particular care to be gentle.
Not uncommonly, the ocular tissues in uveitics are found to be friable, likely due to repeated bouts of inflammation and chronic steroid exposure. The conjunctiva is more likely to tear or bleed, and subconjunctival fibrosis can make dissection more difficult. Scleral flaps can perforate from toothed forceps, avulse, and sutures can cheese-wire through these flaps. The iris can be floppy, dilate poorly, or tear easily, and iris hooks can cheese-wire.
Postoperative inflammation can lead to posterior synechiae and iris bombe, so creation of a surgical iridectomy is often advisable. This is especially true if lysis of posterior synechiae or other iris manipulation was performed.
In uveitics, it is especially important to avoid hypotony that can lead to worsening inflammation or macular edema. Therefore, the surgeon should not leave the operating room until the eye can maintain an appropriate pressure. If necessary, additional sutures should be placed through trabeculectomy flaps; tube shunts need a reliably functioning valve or adequate occlusion. Viscoelastic may be left in the anterior chamber if self-limited postoperative hypotony is anticipated.
Early, aggressive steroid use can be helpful in reducing risk of complications. An intravenous bolus at the conclusion of surgery can be helpful, and consideration should be given to periocular corticosteroids or intravitreal preservative-free triamcinolone. A rapidly tapering course of oral steroids can also help minimize early postoperative inflammation. Prednisolone every 1 to 2 hours, or difluprednate every 3 to 4 hours, should be started and tapered based on the clinical examination. Topical NSAIDs and cycloplegics should be given in most cases.
Sustained-Release Steroid Implants
Eyes with steroid response glaucoma secondary to steroid implants, particularly Retisert (fluocinolone intravitreal implant), behave somewhat differently than a typical uveitic eye. These eyes with sustained-release steroid implants tend to have little, if any, inflammation and typically do not require more than routine postoperative prednisolone use. However, they may have impaired wound healing due to the steroid implant (personal experience), and late conjunctival dehiscence can occur. I recommend meticulous and tension-free conjunctival closure and securely anchoring glaucoma drainage devices (GDDs) with nonabsorbable sutures.
Choosing Surgical Approach
Neither argon laser trabeculoplasty nor selective laser trabeculoplasty are appropriate for the management of uveitic glaucoma. The failure rate can approach 80%, and the chance of causing a flare of uveitis is reported to be 60%.
Glaucoma Drainage Device
GDDs should be considered the mainstay of uveitic glaucoma management. Their effectiveness in the face of recurrent bouts of inflammation is their primary advantage over trabeculectomy.
Due to the potential for acute or chronic aqueous hyposecretion, valved devices such as the Ahmed provide the greatest margin of safety and are often a first choice. However, I have seen several cases of uveitic glaucoma in which an occlusion develops within the valve mechanism, presumably from inflammatory debris.
Baerveldt tubes probably have a higher success rate but also have a higher hypotony risk. With nonvalved devices, hypotony tends to manifest during acute flares of inflammation associated with aqueous hyposecretion but can also occur chronically due to ciliary atrophy. I tend to use the Baerveldt 250 mm2 in cases with well-controlled inflammation when acute aqueous hyposecretion is a lesser risk (steroid implant recipients tend to make good candidates for nonvalved devices). The Baerveldt 350-mm2 implant should be used with caution in uveitics, as it can lead to profound hypotony. I have personally used this device in uveitics only after the patient has proven to scar or encapsulate intensely.
Trabeculectomy With Mitomycin C
Trabeculectomy with mitomycin C (MMC) can provide good long-term IOP control in uveitic glaucoma, although the reported success rate may be lower than with tube implants. The advantages include lack of implanted foreign material and saving glaucoma drainage device surgery as a backup if the bleb eventually fails. However, trabeculectomies tend to be less durable than tubes and probably are not the best choice if there is active or recurrent inflammation or if subsequent surgery (other than clear corneal phacoemul-sification) is planned.
Because eyes with Retisert remain quiet for years, they probably do well with trabeculectomy. Also, eyes with very well-controlled uveitis, or uveitis in long-term remission, may do well with trabeculectomy.
For good reason, cyclophotocoagulation (CPC) is traditionally considered to be contraindicated in uveitis. Because this procedure directly injures uveal tissue, it can cause a severe uveitis reactivation. Furthermore, it may lead to irreversible hypotony. However, there are a few case series suggesting safety and efficacy of transscleral CPC for uveitic glaucoma. Personally, I would still be highly reluctant to try any form of cyclodestruction for treatment of uveitic glaucoma if any type of outflow surgery or medical option remained.
- Patients with uveitis need careful pre- and postoperative planning.
- A prophylactic peripheral iridectomy should be performed if there is lysis of synechia or other manipulation of iris tissue.
- Tube implants are generally preferred for uveitic glaucoma, although trabeculectomy may be appropriate for cases of uveitis in remission.
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