Scleral fixated intraocular lens

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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, and the patient’s ocular anatomy. Many surgeons’ techniques have been described, but this article will focus on the principles and commonly used techniques employed by ophthalmic surgeons in recent years.

IOL choice

Some suture fixation techniques involve tying knots to 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. 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] . A dislocated IOL-capsule complex may also be fixated by passing the suture needle through the capsular bag.

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 has been recently 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

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. Most authors utilize 9-0 or 10-0 double-armed polypropylene suture (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 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 [7][8].

Sutureless scleral fixation

IOL haptics can be externalized and fixated within the sclera without the use of sutures. Many techniques involve the use of scleral flaps or scleral tunnels parallel to the limbus. Haptics can be externalized using 25-gauge forceps or hollow 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].

Hoffman pockets

This technique of suture knot coverage was described in 2006 by Hoffman et al [10] 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 and is 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. Gore-Tex has greater tensile strength and has been reported to have lower suture breakage rates when used in the eye[11]. Gore-Tex is also commonly used for heart valve and vascular procedures.

A recent interventional case series reviewed ab externo scleral fixation of Akreos AO60 and CZ70BD IOLs using 8-0 Gore-Tex suture[12]. 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.

Compared to anterior chamber IOLs (ACIOL) and iris-fixated IOLs, an AAO 2003 meta-analysis failed to find sufficient evidence of superiority of any technique in the published literature to date, both in terms of visual outcomes and complication rates [13]. In general, the rates of corneal edema and glaucoma were slightly higher with ACIOLs, whereas retinal detachment, hypotony, and endophthalmitis rates were slightly increased with sutured IOL techniques.

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%[14].

References

  1. 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.
  2. 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.
  3. Khan et al. Scleral fixation of intraocular lenses using Gore-Tex suture: clinical outcomes and safety profile. Br J Ophthalmol 2016;100:638-643.
  4. 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.
  5. 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.
  6. Holt DG, Young J, Stagg B, Ambati BK. Curr Opin Ophthalmol 2012, 23:62-67
  7. Hoffman RS, Fine H, Packer M. Scleral fixation without conjunctival dissection. J Cataract Refract Surg 2006; 32:1907–1912.

  8. 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.
  9. Gabor SBG, Pavlidis MM. Sutureless intrascleral posterior chamber intraocular lens fixation. J Cataract Refract Surg 2007; 33:1851 – 1854.

  10. Hoffman RS, Fine H, Packer M. Scleral fixation without conjunctival dissection. J Cataract Refract Surg 2006; 32:1907–1912.
  11. 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.
  12. Khan et al. Scleral fixation of intraocular lenses using Gore-Tex suture: clinical outcomes and safety profile. Br J Ophthalmol 2016;100:638-643.
  13. Wagoner MD, Cox TA, Ariyasu RG, et al. Ophthalmology 2003;110:840–859.
  14. Hannush SB. Sutured posterior chamber intraocular lenses: indications and procedure. Current Opinion in Ophthalmology 2000, 11:233–240