Cataract surgery in an eye with uveitic glaucoma
Stepwise approach to surgical success
Cataract surgery in eyes with small pupils is a challenge and having a prior history of uveitis makes it even more so due to the iris synechiae when tend to form. Having a glaucoma seton device in the eye makes it even more difficult since the fluidic balance of phaco surgery is altered due to the additional outflow path (see title photo above). These challenging uveitic cataract cases can be successfully completed using a stepwise approach.
Quiet the inflammation
Patients with uveitis often have recurrent bouts of inflammation that come and go over the course of many years. Since cataract surgery is largely elective, we can defer the procedure until the eye is quiescent without significant inflammation for at least a few months. Some of these uveitic eyes may never return to absolutely zero inflammation, but we can at least reduce it to a very low level. Once the eyes are relatively quiescent, we can schedule the cataract surgery and begin pre-operative topical steroids to help blunt the anticipated post-surgical inflammatory spike.
Topical anesthesia may not be sufficient for this type of cataract surgery because of the anticipated iris manipulation. Using additional injected anesthetics by performing a retro-bulbar, peri-bulbar, or sub-Tenon’s block, is helpful to keep the patient pain-free. The first step will be to use a blunt 27-gauge cannula to get under the iris at the pupil margin and sweep circumferentially in order to release the iris adhesions from the anterior lens capsule. Once these synechaie are released, two instruments can be used to perform gentle pupil stretching to break any fibrotic scar tissue that is preventing dilation. Additional pupil expansion can be achieved by injected viscoelastic at the pupil margin in a technique coined “visco-mydriasis” by Dr Robert Osher.
The capsulorhexis should be made sufficiently large to help prevent recurrent synechiae in the future. The iris tends not to stick to the optic surface of hydrophobic acrylic IOLs, but it will adhere to the anterior lens capsule. This is why it is a good idea to aim for a capsulorhexis that is at least 5 mm in diameter: it will overlap the 6-mm optic of the IOL to hold it securely, but also give a large zone where synechaie are not likely to form.
The fluidics during cataract surgery will be altered by the presence of the glaucoma drainage tube, which will act as an additional outflow area. For balanced fluidics during cataract surgery, the total inflow of fluid must match the outflow. We need to increase our inflow, decrease our pump outflow, or both in order to maintain good fluidic balance during phaco. We also should avoid blocking the lumen of the glaucoma shunt with viscoelastic unless the goal is to specifically prevent outflow during the procedure, in which case it must be aspirated after IOL insertion.
At the end of the cataract surgery, all of the viscoelastic is aspirated and removed from the eye and the phaco incision is closed with a 10-0 nylon suture. To confirm that the glaucoma seton is still functioning properly, a small aliquot of preservative-free triamcinolone acetate is injected into the anterior chamber. Now, balanced salt solution is injected to pressurize the anterior chamber and confirm that the white steroid particles are flowing out the glaucoma drainage tube.
If there is no flow, then the tube is blocked or the footplate of the device has been encapsulated by scar tissue. This is a relatively easy fix that should be addressed now while the patient is still under anesthesia and the eye is in a sterile field. Starting at least a centimeter away from the edges of the footplate, a needle can be used to track under the conjunctiva towards the fibrotic encapsulation tissue. This is then lysed using the sharp bevel of the needle and additional anti-scarring agents can be used to prevent regrowth of these tissues.
These patients are expected to have a more involved post-operative course with higher degrees of inflammation. They may need higher doses of topical steroids and in some cases, sub-tenon’s injection of steroids or oral systemic steroids are warranted. There is also a higher risk of cystoic macular edema, so these patients should receive topical NSAID drops for at least a few weeks after surgery.
Using a stepwise approach, we can successfully complete these complex uveitic cataract cases. These surgeries are very satisfying to perform as a surgeon and more importantly, very beneficial in improving the vision of our patients.
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