Dislocated IOL needs to be repositioned for best performance
A case shows how the optic of a diffractive multifocal IOL must be centered in the visual axis.
For best performance, the IOL optic should be aligned with the patient’s visual axis, and this is particularly true with diffractive optics.
In this case, the patient’s results in the right eye show that when the multifocal diffractive optic is well centered and the refraction is on target, the visual performance from the IOL is excellent. However, looking at the left eye in which the IOL is decentered and the refractive target was not achieved, the visual acuity drops to 20/50. In addition, the quality of the vision is poor with the patient reporting ghosting. We need to reposition this dislocated IOL in the patient’s visual axis and then treat the residual refractive error.
The patient is noted to have about 2 D of corneal astigmatism in each eye, and the right eye achieved a plano outcome without cylinder. Careful examination shows that the right eye has a single-piece toric multifocal IOL placed in the capsular bag and oriented precisely to address the corneal astigmatism. The refractive outcome is excellent with 20/20 distance vision and sharp intermediate and near vision. The left eye has a three-piece multifocal lens in the ciliary sulcus. This three-piece design is best suited for sulcus fixation, but it does not come with the option of toric correction. The patient has a myopic result due to anterior displacement of the optic and still has the 2 D of uncorrected corneal astigmatism. This results in 20/50 vision with ghosting because the diffractive rings are displaced from the visual axis (Figure 1).
The patient was scheduled to return to the operating room for an IOL repositioning for the left eye. The IOL optic is noted to be temporally displaced, and there is vitreous prolapsed through a posterior capsule rupture. This caused the IOL to tilt and shift position as the vitreous displaced the optic. Because the IOL itself is intact and without defects, it will be saved and not exchanged. We simply need two paracentesis incisions to access the IOL, and we do not need to open the original phaco incision. We place these two incisions about 180° apart so that we can have full access to the entire anterior segment (Figure 2).
A small aliquot of preservative-free triamcinolone is placed in the anterior chamber to stain the prolapsed vitreous. The vitreous is behind the optic, and accessing it, even with the small 23-gauge vitrectomy instruments, is difficult. The IOL is then brought up into the anterior chamber with the haptics temporarily placed on top of the iris. This allows the vitrector and infusion instrumentation to be placed behind the optic. Care is taken to avoid placing traction on the vitreous, and we also avoid damaging the remaining capsular support. While it is tempting to use the vitrector to remove some of the capsule in the central visual axis, this could contribute to further IOL instability.
More triamcinolone is injected to confirm that all of the prolapsed vitreous is removed from the anterior segment. Now the IOL can be repositioned into the ciliary sulcus and rotated so that the haptics are at the most secure position. Optic capture is also an option to help ensure long-term stability; however, it can result in a refractive shift. We can then confirm the best centration of the diffractive rings by aligning the Purkinje images with the visual axis. The pupil can be constricted pharmacologically to help secure the IOL position (Figure 3).
On the first postop day, the patient noted subjectively better vision and was seeing 20/40 with a well-centered IOL. The patient still had the residual refraction of mild myopia with 2 D of astigmatism. The patient will need at least 1 month to recover fully from this IOL repositioning procedure and to achieve refractive stability. Then a YAG laser can be used to remove capsular opacities from the visual axis, with care taken not to disrupt IOL support.
The final step is to dial in the refractive outcome to plano with the excimer laser, performing either LASIK or PRK. The treatment will be precise because the ablation is a pure myopic cylinder. This will result in a plano outcome with clear vision to match the other eye.
Our take-home lesson is that with diffractive multifocal IOLs, we must center the optic in the visual axis and achieve a plano outcome in order to get the best visual performance.
Go to cataractcoach.com/category/dislocated-IOL to see surgical video of this case at CataractCoach.com.
- For more information:
- Uday Devgan, MD, is in private practice at Devgan Eye Surgery, Chief of Ophthalmology at Olive View UCLA Medical Center and Clinical Professor of Ophthalmology at the Jules Stein Eye Institute, UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: email@example.com; website: www.CataractCoach.com.