COMPLICATIONS OF GLUED IOL

Ashvin Agarwal, MD and Priya Narang, MS

Glue-assisted intrascleral fixation of an intraocular lens (glued IOL) is a surgical procedure for secondary IOL fixation wherein the transscleral fixation of a posterior chamber IOL (PCIOL) is performed in eyes with inadequate capsular support. Loss of the posterior capsule and its potential support for the IOL is one of the most difficult challenges faced by cataract surgeons. Ever since the glued IOL technique was introduced in 2007, it has evolved with numerous modifications adopted by surgeons across the globe, and the technique has extended its application with excellent results.^1–38 Intraoperative capsular loss, zonular dialysis, congenital subluxated lens, ectopia lentis, and traumatic subluxation are the common surgical indications.

IOL Stability in Glued IOL Surgery

IOL dislocation is one of the main problems associated with transscleral fixation of suture-fixated IOLs. However, in our technique, the IOL haptic is secured inside scleral pockets at the site where the tip is externalized. We routinely tuck the haptic tip inside the Scharioth scleral tunnel made with a 26-gauge needle. Another concern is the change in the properties of the biomaterial when the IOL is placed in a stretched position. The 2 factors that contribute to the ability of IOL loops to maintain their original symmetrical configuration are loop rigidity (the resistance of the haptic to external forces that bend the loops centrally) and loop memory (the ability of the loops to re-expand laterally to their original size and configuration). These 2 factors can be demonstrated by compressing or stretching the haptics in vivo (Figure 44-1). In vivo, the centrifugal force vector due to resistance to compression by the capsular bag keeps the IOL stable (Figure 44-2A). Conversely, stretch creates a centripetal resistance force. Along with the intralamellar scleral tuck, this stabilizes the IOL (Figure 44-2B). Although complete scleral wound healing with collagen fibrils may take up to 3 months, the IOL remains stable because the haptic is snugly placed inside a scleral pocket. IOL centration/tilt was followed both clinically and with anterior segment optical coherence tomography. The difference between the topographic (Orbscan) and manifest refraction was constant in all eyes during the entire postoperative period, which suggests minimal new IOL-induced astigmatism. Moreover, the stability of the IOL is well maintained by the tucking procedure.

Although the glued IOL procedure is free from conventional suture-related complications of sutured scleral-fixated IOL, it can predispose to a few complications intra- and postoperatively if not managed well. Anterior vitrectomy forms the most essential aspect of performing a successful glued IOL procedure, and although the operating surgeon’s skill is one of the key factors in handling these complicated eyes, the patient selection, the type of IOL, the preoperative work-up, and the postoperative follow-up are crucial in minimizing and managing complications.

Scleral flaps are supposed to be 180 degrees diagonally apart (Figure 44-3). Nondiagonal flaps as little as 5 to 10 degrees off also can affect the final positioning of the IOL. Surgery should not proceed with eccentric flaps because sclerotomy is to be done beneath these flaps and a path created for the externalization of haptics. This eventually would lead to decentration of the IOL (Figure 44-4). A fresh flap should be created diagonally opposite to the previous one and then the surgery should proceed to the next level.

TORN SCLERAL FLAPS

The scleral flaps get torn if the flaps are of uneven thickness and when the dissection plane is either too superficial or the hinge of the scleral flap is accidentally torn off due to misdirection of the crescent blade. In this situation, new flaps should be dissected, and if the flap gets accidentally dislodged from the hinge, then the flap can be placed separately aside and then repositioned and stuck to the scleral bed with glue once the surgery is over.

SMALL SCLERAL FLAPS

An adequate scleral flap ranges from 2 to 2.5 mm. Flaps smaller than 2 mm are difficult to handle and often get damaged. Too-narrow flaps should be avoided, as it may be difficult to create the scleral pocket next to the sclerotomy.

When too-wide or too-large flaps are created (Figure 44-5), the length of haptic underneath the flaps is more than the one in the scleral tunnel. This should be avoided as a greater amount of haptic length is wasted from the sclerotomy site to the entry point of the scleral pocket. As a result, the proportion of haptic tucked is less.

THIN SCLERAL FLAPS

Normal scleral flap thickness should be about 40% depth. Superficial flaps can lead to postoperative thinning or erosion of haptics.

PREMATURE SCLERAL ENTRY

Accidental scleral entry while dissecting the scleral flaps can occur rarely. This can be prevented by positioning the crescent blade bevel-up throughout the dissection.

Sclerotomy-Related Issues

ANTERIOR SCLEROTOMY

Sclerotomy should be placed 1.0 to 1.5 mm from the limbus. Anteriorly (< 1 mm) placed sclerotomy often leads to injury to the iris root and possible bleeding. In eyes with greater white-to-white diameter, anterior sclerotomy is often performed. This shifts the plane of IOL anteriorly, allowing more haptic externalization. During this endeavor, the peripheral iris often gets entrapped into the needle that is employed for sclerotomy, resulting in iridodialysis, hyphema, and occasionally an iris tear or an accidental creation of a sclerotomy channel that is anterior to the iris plane. To avert this complication, peripheral iridectomy is performed in eyes with greater white-to-white diameter undergoing glued IOL procedure (Figures 44-6 through 44-8). When using an anterior chamber maintainer, it may help to turn off the infusion when making the sclerotomies.

POSTERIOR SCLEROTOMY

Sclerotomy placed more than 2 mm behind the limbus has the risk of posterior shift in the plane of the IOL because there is a lesser amount of haptic available for the scleral tuck. In this situation, the haptic should be reinternalized, a new sclerotomy should be made 1.0 mm from the limbus, and the haptic reexternalized.²⁹ If necessary, the surgeon can perform a single-pass four-throw pupilloplasty procedure to prevent optic capture.

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