Challenges with foldable intraocular lenses with hollow haptics or eyelets in scleral fixation.

There has been great interest on new surgical techniques for secondary intraocular lens (IOL) implantation in the absence of capsular support in the past several years. Between January 2020 and February 2021, at least 15 publications on this subject have appeared in this journal alone, featured within the different article types (eg, full-length article and correspondence). Off-label, scleral fixation of posterior chamber, foldable IOLs with hollow haptics or eyelets seemed to be among the techniques proposed that gained considerable popularity. Primary functions of such design features incorporated into some IOLs include even transmission of forces, enhancement of rotational stability, and facilitation of intraoperative lens manipulation during inthe-bag implantation. A foldable lens initially considered ideal for scleral fixation was the Akreos AO60 IOL (Bausch & Lomb, Inc.), a single-piece, plate-type lens with 4 closed loops, manufactured from a hydrophilic acrylic material. The possibility for a 4-point fixation was considered one of the main advantages of this lens design, minimizing the risk of IOL tilt inherent to methods using a 2-point fixation. Different studies described scleral suture fixation of the AO60 IOL using Prolene (polypropylene) or Gore-Tex (polytetrafluoroethylene) sutures. This latter has greater tensile strength than polypropylene, and although it has gained popularity among ophthalmic surgeons, its use in the eye is considered off-label. Sutureless, intrascleral fixation of the AO60 IOL has also been described using the 4-flanged technique proposed by Canabrava et al. However, some surgeons who were initially enthusiastic about using this and other hydrophilic acrylic IOLs with similar design characteristics for scleral fixation moved away from it owing to concerns about postoperative IOL opacification, related to calcification. Indeed, a specific pattern of postoperative IOL calcification has been described in eyes undergoing multiple surgical procedures. This has not been associated with any specific IOL model, but all IOLs affected are made of hydrophilic acrylic materials. The calcified deposits are observed on an overall round area of the anterior surface/subsurface of the lens, generally limited by the capsulorhexis opening (in IOLs implanted within the capsular bag). The deposits are more widespread on the anterior IOL surface/subsurface of hydrophilic acrylic IOLs that had been scleral fixated. This calcification pattern was first described after procedures using intracameral injections of air or gas in pseudophakic eyes, such as Descemet-stripping endothelial keratoplasty. However, the same pattern was also observed after procedures performed in the posterior segment of pseudophakic eyes, including those without the use of any vitreous tamponade (eg, intravitreal injections of antivascular endothelial growth factor drugs). Retrospective studies found that the rate of calcification after posterior lamellar keratoplasty in pseudophakic eyes could be between 5.0% and 9.7%. It is noteworthy that 2 new innovative foldable IOL designs have been recently developed specifically to be used for sutureless scleral fixation. One of them is the Carlevale IOL (Soleko), and the other is the CM-T Flex (Appasamy Associates). Both IOLs have an overall plate-type design, with transscleral T-shaped haptics or plugs, which are exteriorized through sclerotomies locking the IOL in position using the horizontal limbs. They are both manufactured from hydrophilic acrylic materials. Although there is, to date, to my knowledge, no reports of postoperative opacification of these designs after scleral fixation, the higher susceptibility of hydrophilic IOLs to postoperative calcification in comparison with other IOL materials warrants vigilance. Considering the aforementioned concern related to hydrophilic acrylic materials, another foldable IOL that also started to be considered an ideal candidate for scleral suture fixation was the enVista IOL (model MX60, Bausch & Lomb, Inc.). This is a hydrophobic acrylic IOL with water content of approximately 4%, which was U.S. Food and Drug Administration (FDA) approved in 2012. It is a single-piece design with open loops, with 2 eyelets located at the optic–haptic junctions. This foldable IOL allows scleral suture fixation through a 1.80 mm corneal incision, with reportedly great stability likely because of 4 points of support, namely, the 2 sutures fixed to the eyelets and the 2 haptics placed in the ciliary sulcus. Although this IOL has an excellent safety profile when implanted in the capsular 559