BLOG: Surgical workarounds can address compromised capsules during cataract surgery
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Last month we explored the risk factors for a compromised capsule during cataract extraction. We will now explore different surgical options for lens implantation in the face of this complication, as well as their risks and benefits.
As mentioned in the previous entry, poor capsular strength could disqualify a patient for implantation of a toric or a multifocal specialty IOL where centration and stability is paramount. However, depending on the level of capsular compromise, the surgeon may also have decisions to make for implantation of a single focus IOL.
One possibility is for the lens to be placed in the ciliary sulcus with optic capture of the lens. The haptics in the ciliary sulcus alone is not adequate to hold the lens, but with the additional step of popping the IOL optic back into the capsular bag, the two work together to provide stable placement of the lens. Some consider this the next best option after standard, fully in-the-bag cataract extraction (CE). But as modern IOL calculations assume a capsular-placed lens, a slight “fudge factor” may be needed to alter the strength of an optic capture-implanted IOL to maintain the intended target outcome. With any secondary technique the patient’s refractive outcome becomes suspect.
If there is not enough capsule for this technique, an IOL can also be iris-sutured for additional stability, but even permanent sutures break down over time or can “cheese wire” through the iris. Then, even with a successful outcome, the patient may still complain of cosmesis due to corectopia.
In the case of no capsular support, a practiced surgeon may instead consider scleral fixation of the IOL. This technique has the surgeon thread the haptics of the IOL through the sclera and melt the plastic haptic end to form a bulb, effectively locking it in place. Like any secondary choice there is compromise with scleral fixation, again with the lens not sitting where initial calculations assumed it would, but also risk for long-term erosion from the haptics, lens tilt and overall poor lens stability.
As a final choice, an entirely different calculation would be needed to place an anterior chamber IOL (ACIOL), a lens that we all know has its drawbacks, or the patient may be left aphakic, the surgeon cutting their losses and having the patient return for secondary IOL placement another day. If an ACIOL is chosen, a concurrent peripheral iridectomy is usually performed to prevent pupillary block.
An ACIOL should not be used in patients with known endothelial disease, peripheral synechiae, neovascularization of the angle or iris compromise. While uveitis-glaucoma-hyphema syndrome is less common with modern ACIOLs it is still possible; they can also cause endothelial damage leading to bullous keratopathy in extreme cases.
In addition to its uses for the stability of the IOL, the capsule plays another important role: acting as a barrier between the anterior and posterior segment. Along with the anterior hyaloid membrane, the capsule prevents the migration of vitreous into the anterior chamber. Vitreous in the anterior chamber alone isn’t an issue, but it can increase a patient’s risk for a retinal tear or detachment, cystoid macular edema and endophthalmitis if it extends to the surgical wound or paracentesis (have increased suspicion if a peaked pupil is noted toward one of these incisions postop).
To better understand these retinal risks, imagine that the vitreous traveling further anterior means more vitreoretinal traction at the back of the eye. The vitreous now stretches over a larger area with traction potentially inducing a retinal tear or macular edema. A dilated fundus exam is called for at the 1-day postop visit for patients with a known capsular tear, and they should be thoroughly educated on signs and symptoms of retinal detachment. If it was not previously indicated, a topical NSAID may be added to the patient’s postop regimen.
Because of the risks mentioned, you may see a complex cataract case include an anterior vitrectomy to reduce forward vitreous migration. This is not done lightly, as the vitrectomy itself has risks, and the procedure often includes an injection of triamcinolone to help the surgeon visualize the vitreous. Predictably, the steroid can cause IOP spikes and floaters that can take months to dissipate. Slit lamp examination can show significant white, powdery deposits that may settle out inferiorly (in this case not a hypopyon) or be seen at the pupillary margin.
Thankfully, even in the event of a compromised capsule, surgeons have several workarounds. Unfortunately, none are as quite as safe or stable as what is now standard: extracapsular cataract extraction with in-the-bag IOL placement. Once this option is taken away, many factors come into play steering how a surgeon chooses to implant the IOL including the patient’s other ocular pathology, the degree of capsular tear or zonular loss, and even what technique the surgeon is most comfortable with.
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