We describe a suture fixation technique for a single-piece foldable acrylic closed-loop intraocular lens (IOL) (C-flex™, Rayner).
In our experimental model analyzing the stability of acrylic haptics, we confirmed that the IOL could be in counterpoise without tilt using only a two-point fixation. This new surgical technique was performed in seven patients.
The unique haptic design allows easy and secure suture fixation. The clinical outcomes were encouraging.
It is conceivable that better stabilization can be achieved by the broad arc of distal haptic-tissue contact, in addition to suture fixation, using our surgical technique with the C-flex™ IOL.
The eyelets on the polymethyl methacrylate (PMMA) intraocular lens (IOL) haptics permit sutures to be placed easily at symmetrical points. Various four-point fixation techniques using the eyelets have been shown to yield better stability and prevent tilt.
We speculated that a closed-loop design of a Rayner single-piece acrylic IOL (C-flex™) could serve the function of eyelets. However, it has not yet been determined if suture fixation using the acrylic haptics results in stability of the IOL, which is very flexible. In this study, we conducted a simple experiment to clarify this issue with regard to patient application.
We designed an experimental model using Vernier calipers in which a cylindrical bar with a groove approximately 0.3 mm in depth was attached perpendicular to the outward gauge tip to prevent slippage of the sutures. A blue IOL was used for better contrast with the background.
Based on reports regarding the mean diameter of the ciliary sulcus,
All surgeries were performed by a single surgeon. Two fornix-based conjunctival peritomies were made 180 degrees apart (usually from 2 to 4 o'clock and from 8 to 10 o'clock) followed by the construction of 3×3 mm partial thickness triangular limbus-based scleral flaps. One arm of a double-armed 10-0 Prolene (Ethicon, STC6) suture on a long straight needle was passed 1 mm posterior to the limb ab externo underneath the scleral flap and docked into a 26-gauge needle inserted in a similar fashion from the opposite side. The 26-gauge needle with the 10-0 Prolene suture was then withdrawn, resulting in the 10-0 Prolene suture bridging the posterior chamber. The suture was then externalized through a 3.0 mm beveled corneal incision (12 o'clock position) using a Sinskey hook and cut. Before placing the IOL in the injector, one end of the 10-0 Prolene suture was threaded through the injector and tied at point A on the leading haptic. The IOL was then loaded into the injector and the leading haptic was inserted into the posterior chamber (
It was not necessary to extend the corneal incision because the diameter of the insertion tip was only 2 mm. The trailing haptic was purposefully left outside the eye and secured with the other end of the 10-0 Prolene suture before insertion into the posterior chamber (
Three of the seven patients underwent this procedure in combination with a pars plana vitrectomy, one of whom underwent this procedure in combination with both a pars plana vitrectomy and an intravitreal gas injection (
There were no significant complications such as vitreous or choroidal hemorrhage, retinal detachment, or endophthalmitis during the follow-up period.
Three-piece foldable IOLs have been used for suture fixation through a small incision because PMMA haptics confer mechanical stability.
In suture fixation of IOLs without eyelets on the haptics, the point of maximum haptic spread has been used to accurately place sutures.
In all cases, point B of the haptic was selected as a suture placement site. It is impossible to achieve haptic-tissue contact due to the short diameter of the haptic spread (10 mm) at point B. However, the diameter of the haptic spread increases gradually toward the distal portion of the haptic, and the diameter of the haptic spread at point A (12 mm) exceeds the mean diameter (11 mm) of the ciliary sulcus. Consequently, a portion close to the ends of the haptics contacts the tissue in a broad arc, this presumably results in increased stability of the IOL (
Kuckle et al
The incidence of vitreous hemorrhage is increased in the previously described four-point fixation technique, in which four scleral punctures are required. However, IOL stability can be achieved immediately following surgery.
Taskapili et al
However, some considerations should be given to suture fixation of the C-flex™ IOL. First, it is technically difficult to produce a wide haptic-tissue contact area because of the relatively shorter overall diameter of the IOL in patients with severe myopia. In these patients, IOLs with longer haptic spreads are recommended. In this study, one patient with severe myopia (axial length: 30.05 mm) had postoperative decentration, probably due to a short haptic spread compared to the diameter of the ciliary sulcus. Second, chronic inflammation can be induced by rubbing between the iris and the IOL optic since the C-flex™ IOL has no haptic angulation. However, a previous study reported that contact between the iris and the IOL optic was observed in IOLs with haptic angulations ranging from 5 to 10 degrees, even when the IOLs were properly sutured at the ciliary sulcus.
In summary, the closed-loop design of the C-flex™ IOL allows easy and secure suture fixation, even in vitrectomized eyes. In addition, we believe that our fixation technique using the unique haptic design of the C-flex™ IOL has clinical outcomes similar to those of the four-point fixation technique. However, further studies with a larger number of cases and a longer follow-up period are needed to evaluate the safety and effectiveness of our suture fixation technique.
Schematic drawing of a C-flex™ IOL with wide haptic-optic junctions (3 mm in length). Point A is colored in green and point B is colored in blue.
Suture fixation of a C-flex™ IOL in our experimental model. (A) Each step was carried out in a horizontal plane using a level. (B) and (C) Close-up photographs after suture fixation.
One free end of the suture is passed from the 8 o'clock position through the insertion tip of the injector and tied to the leading haptic. The IOL is loaded into the injector after the suture is pulled out with forceps and tied at the leading haptic.
The other free end of the suture is passed from the 2 o'clock position and tied to the trailing haptic outside the eye.
Slit-lamp examination at 1 week after surgery. (A) A well-centered IOL. (B) An IOL slightly decentered in an inferior direction.
The broad arc of distal haptic-tissue contact in the two-point suture fixation technique.
Clinical Characteristics of Patients (N=7)
VR=vitreoretinal; NPDR=non-proliferative diabetic retinopathy; PDR=proliferative diabetic retinopathy; PPV=pars plana vitrectomy; VH=vitreous hemorrhage; TRD=tractional retinal detachment; SF6=sulfur hexafluoride.
Visual Outcomes
BCVA=best corrected visual acuity; UCVA=uncorrected visual acuity; HM=hand motions; CF=counting fingers.