(scroll down for full video of four-point fixation of an IOL to the sclera)
Cataract surgery has an amazing success rate and it is anticipated that less than 1% of IOLs will become dislocated after routine phacoemulsification. Certain pre-existing conditions such as pseudo-exfoliation syndrome, Marfan syndrome, and traumatic zonular loss can pre-dispose patients to late dislocation of the IOL even in the setting of a technically perfect original cataract surgery. In those cases where the IOL is subluxed and visual acuity is compromised, there are multiple approaches to rectify the situation and restore vision to our patients.
Position of the IOL
The operative report from the original cataract surgery can be helpful to ascertain if there were surprise findings or complications. Determine if the IOL was placed in the capsular bag or perhaps it was in the ciliary sulcus. Loose zonules may have been noted during the original procedure. Was the case uneventful or was there a posterior capsule rupture? Finally note which type of IOL was placed and its dioptric power.
The current examination of the patient also yields valuable information. If the IOL is just behind the iris and seemingly accessible from an anterior segment approach, note the degree of pseudo-phakodonesis. Determine if the IOL is still within the capsular bag or if it is in the sulcus. If in the sulcus, are there strands of vitreous surrounding the optic or haptics? Recline the exam chair and place the patient in the supine position. Now using the indirect ophthalmoscope, note the position of the IOL. If the IOL has fallen back into the mid-vitreous then an anterior approach to surgery is contra-indicated. Patients with IOLs that are engulfed in vitreous and dislodged into the vitreous cavity will do best with a posterior approach pars plana vitrectomy by a retinal specialist.
Keep or Exchange the IOL
The type of IOL and its dioptric power and important considerations when determining whether to keep or exchange the current dislocated IOL. If the IOL power was noted to be ideal for the eye and it is a three-piece IOL, then we would lean towards keeping the existing IOL and simply fixating it in the eye for long term stability. If we note damage to the IOL, it may be best to replace it. Also for cases where there is a significant, undesirable refractive error, and IOL exchange may be warranted.
The type of IOL will determine the ability to place it in the ciliary sulcus or fixate it to the iris or sclera. Single-piece acrylic IOLs have thick haptics which can damage the posterior surface of the iris if placed in the ciliary sulcus. For this reason, most dislocated single-piece acrylic IOLs are removed from the eye once they become dislocated. A three-piece IOL offers more options for placement and is generally considered more versatile in these difficult cases.
Methods of IOL Fixation
Sewing the IOL haptics to the posterior surface of the iris can be done in cases where the IOL dislocation is mild to moderate. This is typically done using 10-0 polypropylene on a long needle using the Siepser or McCannel suture techniques. Sutures placed at the pupil margin can induce significant distortion of the pupil, so placement at the mid iris is preferred. An ovoid pupil can still result, so patients should be warned not to expect a perfect cosmetic outcome. Since the iris is fragile, a substantial bite of iris stroma is needed to prevent cheese-wiring of the tissue. These sutures typically last for many years, but trauma and other factors can cause them to break and for the IOL to dislocate again in the future.
The traditional method of scleral fixation of an IOL was using a suture such as 10-0 polypropylene, but many surgeons have since moved away from this technique due to the limited lifespan of these sutures which can be as short as a few years due to friction and traction. Dr. Amar Agarwal innovated the glued IOL technique which uses intra-scleral pockets and tissue glue to securely fixate the externalized haptics of a three-piece IOL. Many surgeons have migrated to using stronger suture materials such as GoreTex to fixate a specially designed single-piece acrylic IOL which has four closed loop haptics. This method should provide many years, and perhaps decades, of stability. Scroll down to watch the video of vitreo-retinal surgeons Michael Klufas MD and Pradeep Prasad MD performing this technique.
Placing an anterior chamber IOL (ACIOL) can be a great alternative to fixating an IOL in the posterior segment. The track record of ACIOLs is many decades long and the results can be every bit as good as a suture fixated posterior chamber IOL. These IOLs will require a larger incision and they should be properly sized to the anterior segment and a peripheral iridotomy should be made at the time of surgery.
Using a step-wise approach and careful planning, our patients who suffer from a dislocated IOL can have excellent results from a revision surgery to re-fixate their IOL or replace it with a new one.