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Repositioning a dislocated IOL can be complicated but have good results
There are several IOL options available to ensure long-term stability.
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Despite our best efforts, complications happen during cataract surgery, and often it is not surgeon error, but rather weakness or irregularity in the tissue of the patient. When cataract surgery patients do not have a sufficient degree of capsular support, alternative methods of IOL placement must be used. Placing a three-piece IOL in the ciliary sulcus is a commonly used technique that can give great long-term results and stability. Sometimes, however, the IOL can become dislodged and require a second surgery for repositioning.
Preoperative evaluation
During the slit-lamp microscope examination, the IOL position should be carefully noted, as well as the stability. When the patient shifts gaze, a loose IOL will shake or move. Also, check for IOL movement while examining the patient in a reclined position using the binocular indirect ophthalmoscope because the supine position is what you will encounter in the operating room. Retroillumination techniques (Figure 1) allow details such as capsular defects to be seen better than direct lighting. Have the patient look in all quadrants for maximum evaluation of the retro-iris space.
Figure 1. This patient has a three-piece acrylic IOL which has subluxed inferiorly and is in jeopardy of dislocating into the vitreous cavity. Direct illumination (left frame) shows many details but retro-illumination (right frame) is required to see the linear break in the capsular bag.
Images: Devgan U
Potential IOL options include a posterior chamber IOL placed in the ciliary sulcus, a posterior chamber IOL fixated to the iris or sclera or an anterior chamber IOL. Each of these options has merits and potential side effects, and studies have shown that long-term results are good with each of them. An anterior chamber IOL works well in situations in which there is no capsular support, while a sulcus posterior chamber IOL works best in cases in which there is a sufficient rim of anterior capsule. The IOL calculations for an anterior chamber IOL are done with the standard formulae using the lower A-constant of the IOL, which accounts for its more anterior position within the eye. For a sulcus posterior chamber IOL, the IOL power is calculated using the A-constant but then dropped to account for the sulcus placement (Table).
Source:Devgan U
Intraoperative techniques
The existing IOL can be repositioned or exchanged for a new one, but in either case the IOL must not be allowed to further descend into the vitreous cavity. The first step is to make a small limbal incision and use microforceps to securely grab the visible haptic (Figure 2a) and bring it into the anterior chamber where it can be secured. At this point, viscoelastic can be injected under the IOL optic to further support it and create a barrier to avoid vitreous prolapse (Figure 2b). The entire IOL can then be brought into the anterior chamber while the iris can be lifted to assess the degree of available capsular support (Figure 2c). If sufficient capsular support is noted, a hook or chopper can be used to carefully place the haptics in those meridians (Figure 2d). If not, fixation with suture or mechanical means can be done to the iris or the sclera but the IOL power should not be adjusted from the standard in-the-bag calculation. Alternatively, an anterior chamber IOL can be placed with a peripheral iridectomy to avoid pupillary block. For an IOL that is placed entirely in the ciliary sulcus, miotic agents can be instilled to prevent pupillary capture of the optic during the initial postop period.
Figure . (A) The first step is to grab the accessible haptic with microforceps to prevent the IOL from dislocating into the vitreous cavity. (B) With one haptic secured above the iris, viscoelastic is injected under the optic to provide further support. (C) The chopper or hook is used to bring the remaining haptic into the anterior chamber. (D) With the IOL in the desired orientation for maximal sulcus support, the hook is used to carefully tuck the haptics under the iris and into the ciliary sulcus.
Postoperative management
The IOL repositioning or exchange surgery is more complicated than the original cataract surgery, and more inflammation should be expected in the postop period. Intracameral injection of triamcinolone can help control inflammation and also provide visualization of any prolapsed vitreous. Prolonged use of topical steroids and NSAIDs can aid in healing while minimizing discomfort. Complications such as macular edema, vitreous traction, retinal detachment and endophthalmitis are infrequent but still occur more commonly than in routine cataract surgery.
Patients can rest assured that even if their tissues are weaker than average, there are still options for IOL placement. With the IOL optic well-centered and secured, the patients can recover excellent vision with great long-term stability.