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Options for intraocular lens (IOL) implantation in the absence of capsular support include anterior chamber IOLs, iris-fixated IOLs, and scleral-fixated IOLs. Choice of IOL and implantation technique depends greatly on patient age, comorbid ocular conditions, the patient’s ocular anatomy, and surgeon comfort level with a specific technique. Many different techniques have been described, but this article will focus on commonly used techniques for scleral-fixation of IOLs employed by ophthalmic surgeons in recent years.
IOL choice
Some suture fixation techniques involve tying knots directly to the haptic of a 1 or 3-piece IOL [1] [2]
The Alcon CZ70BD PMMA lens contains eyelets along the haptics that facilitate suture fixation and requires a 7 mm incision as it is not foldable. The Bausch & Lomb Akreos AO60 hydrophilic acrylic lens contains 4 eyelets through which suture can be passed, providing 4 point fixation[3] . The Bausch & Lomb enVista MX60 IOL is a hydrophobic acrylic IOL that contains eyelets at the 2 haptic-optic junctions [4] . The Zeiss CT Lucia 602 is 3-piece hydrophobic acrylic IOL with polyvinylidene fluoride (PVDF) monofilament haptics. that are much more durable than prolene and less likely to break with suture fixation. Recently, a new single piece hydrophilic acrylic lens, the Carlevale IOL, has been introduced in Europe. It can be introduced through a small corneal incision and has two plugs on the end of the haptic which are threaded through a sclerotomy and anchor the lens to the sclera. The plug is then covered by conjunctiva. It is currently not available in the United States.
As most IOL power calculations are based on endocapsular IOL localization, power adjustment is necessary to account for a more anteriorly positioned lens in the ciliary sulcus.
Calcification of hydrophilic acrylic IOLs (Akreos) has been reported following procedures involving intraocular gas or air [5]. This may be an important consideration in patients who are at increased risk of requiring retinal detachment repair or endothelial keratoplasty in the future.
Fixation techniques
A dislocated IOL-capsule complex may also be fixated by passing the suture needle through the capsular bag.
Ab externo suture fixation
Ab externo fixation refers to scleral fixation in which sutures are passed from the outside to the inside of the eye. The location of the ciliary sulcus is established using external landmarks. 9-0 or 10-0 double-armed polypropylene suture (Prolene) can be utilized, although Gore-tex is becoming more popular. When using prolene, the suture needle may be straight (STC-6), which provides longer range of access, or curved (CIF-4 or CTC-6), which provides a more rigid needle [6]. A hollow 27-gauge or 30-gauge needle can be used as a docking guide to ensure exit of the suture needle through the correct site in the sclera. Scleral flaps, tunnels, or grooves can be used to protect the knot and prevent external suture erosion.
Ab interno suture fixation
In ab interno fixation, the suture is passed from the inside to the outside of the eye. In order to avoid a blind pass through the ciliary sulcus, the suture needle can be inserted into and externalized using a hollow needle that was placed at a known landmark or by utilizing endoscopic visualization or using a hand over hand technique with intraocular forceps [7][8].
Sutureless scleral fixation
IOL haptics can be externalized and fixated within the sclera without the use of sutures. Some techniques involve the use of scleral flaps or scleral tunnels parallel to the limbus. Haptics can be externalized using 25-or 27-gauge forceps or 30G-thin wall needle. Scleral flaps can then be closed with 10-0 nylon or fibrin glue. Some authors recommend using larger IOLs for these techniques in order to prevent torsion of the haptics and subsequent scleral erosion or IOL dislocation [9]. The Yamane technique for intrascleral IOL fixation has become increasingly popular, avoiding the need for a conjunctival peritomy or scleral flaps [10].
Hoffman pockets
This technique of suture knot coverage was described in 2006 by Hoffman et al [11] and avoids the need for conjunctival dissection, scleral cauterization, or scleral wound closure. A scleral pocket is created by initiating a scleral tunnel from a clear corneal incision. A double-armed suture can then be passed full thickness through the conjunctiva and scleral pocket, and the suture ends can be retrieved subsequently through the external corneal incision. The knots can then be buried within the pockets.
Suture material
Polypropylene
Polypropylene (Prolene) is a monofilament polymer composed of propene used to be the most commonly used suture material for scleral-fixated IOLs.
Rates of suture breakage have been reported from 0 to 27.9% with 10-0 polypropylene. For this reason, 9-0 polypropylene has been increasingly used in order to reduce the rate of breakage.
Gore-Tex
Gore-Tex (W.L. Gore & Associates, Elkton, Maryland, USA) is a non-absorbable, polytetrafluoroethylene monofilament suture that is being increasingly used for scleral-suture fixation. Gore-Tex has greater tensile strength and has been reported to have lower suture breakage rates when used in the eye[12]. Gore-Tex is also commonly used for heart valve and vascular procedures.
A interventional case series reviewed ab externo scleral fixation of Akreos AO60 and CZ70BD IOLs using 8-0 Gore-Tex suture[13]. In the technique described in this report, four separate sclerotomies were made, each 2 to 3 mm from the limbus. The suture is passed through an eyelet of the IOL, into the anterior chamber through a main incision, and then externalized through one of the 4 sclerotomy sites. In cases using the AO60, the other end of the suture is then passed through the adjacent eyelet. The second suture end is then passed into the anterior chamber and out through the adjacent sclerotomy. The same is done with the opposite eyelets and sclerotomies using a second piece of Gore-Tex suture. The IOL is then inserted into the anterior chamber through the main incision. The suture knots are trimmed and rotated within one of the sclerotomies.
Prognosis
Visual outcomes of scleral fixated IOLs are good, with poor outcomes typically related to comorbid ocular conditions. Few retrospective studies directly compare techniques.
A recent ophthalmic technology assessment by the American Academy of Ophthalmology [14] showed no superiority of a single IOL implantation technique in the absence of zonular support, although the 45 studies included had insufficient statistical power to compare the techniques conclusively.
Complications
Complications of scleral-fixated IOLs include corneal edema, retinal detachment, intraocular hemorrhage (due to the passage of suture through uveal tissue), suture erosion and infection (due to externalized or exposed sutures), and IOL dislocation or tilt. Caution is necessary in patients with a history of high myopia, hypertension, scleritis, or scleromalacia as well as those on anticoagulant medication. The risk of complications may correlate with increased surgical time and manipulation. Hypotony, which occurs when IOL implantation is performed with penetrating keratoplasty, also increases the risk of suprachoroidal hemorrhage, ranging from 0 to 2.2%[15].
Additional Resources
- Yeu E. Intraocular Implants (IOLs). American Academy of Ophthalmology. EyeSmart/Eye health. https://www.aao.org/eye-health/treatments/intraocular-implants-iols. Accessed February 08, 2023.
References
- ↑ Ma KT, Kang SY, Shin JY, et al. Modified Siepser sliding knot technique for scleral fixation of subluxated posterior chamber intraocular lens. J Cataract Refract Surg 2010; 36:6-8.
- ↑ Kim DH, Heo JW, Hwang SW, et al. Modified transscleral fixation using combined temporary haptic externalization and injector intraocular lens implantation. J Cataract Refract Surg 2010; 36:707 – 711.
- ↑ Khan et al. Scleral fixation of intraocular lenses using Gore-Tex suture: clinical outcomes and safety profile. Br J Ophthalmol 2016;100:638-643.
- ↑ Rho S, Song WK, Sung Y, et al. Scleral fixation technique using a hydrophobic foldable intraocular lens with ring-shaped connecting bridges. J Cataract Refract Surg 2015;41(2).262-267.
- ↑ Nieuwendaal CP, van der Meulen IJE, Patryn EK, et al. Opacification of the Intraocular Lens After Descemet Stripping Endothelial Keratoplasty. Cornea 2015;34:1375-1377.
- ↑ Holt DG, Young J, Stagg B, Ambati BK. Curr Opin Ophthalmol 2012, 23:62-67
- ↑ Hoffman RS, Fine H, Packer M. Scleral fixation without conjunctival dissection. J Cataract Refract Surg 2006; 32:1907–1912.
- ↑ Olsen TW, Pribila JT. Pars plana vitrectomy with endoscope-guided sutured & posterior chamber intraocular lens implantation in children and adults. Am J Ophthalmol 2011; 151:287 – 296.
- ↑ Gabor SBG, Pavlidis MM. Sutureless intrascleral posterior chamber intraocular lens fixation. J Cataract Refract Surg 2007; 33:1851 – 1854.
- ↑ Shin Y, Sato S, Maruyama-Inoue, Kadonosono K. Flanged intrascleral intraocular lens fixation with double-needle technique. Ophthalmology 2017;124:1136-1142
- ↑ Hoffman RS, Fine H, Packer M. Scleral fixation without conjunctival dissection. J Cataract Refract Surg 2006; 32:1907–1912.
- ↑ Nottage JM, Bhasin V, Nirankari VS. Long-term safety and visual outcomes of transscleral sutured posterior chamber IOLs and penetrating keratoplasty combined with transscleral sutured posterior chamber IOLs. Trans Am Ophthalmol Soc 2009;107:242–50.
- ↑ Khan et al. Scleral fixation of intraocular lenses using Gore-Tex suture: clinical outcomes and safety profile. Br J Ophthalmol 2016;100:638-643.
- ↑ Shtein RM, Weikert MP, Li JY, et al. Intraocular Lens Implantation in the Absence of Zonular Support: An Outcomes and Safety Update: A Report by the American Academy of Ophthalmology 2020;36:707-711.
- ↑ Hannush SB. Sutured posterior chamber intraocular lenses: indications and procedure. Current Opinion in Ophthalmology 2000, 11:233–240
