Extraocular needle- guided haptic insertion technique of scleral fixation intraocular lens surgeries (X-NIT).

The most challenging step in sutureless scleral fixation of intraocular lens (SFIOL) is exteriorization of haptics. The conventional handshake technique has a learning curve since it involves intraocular handing over of haptics from one forceps to another. Here, we describe "extraocular needle-guided haptic insertion technique" (X-NIT), a novel technique of exteriorizing haptics that totally eliminates intraocular manipulations. This method involves sequential introduction of two bent 26-gauge needles through the sclera (pars plicata zone) into the eye which are brought out through a sclerocorneal wound. The intraocular lens haptics are threaded through these needles and exteriorized. Nineteen consecutive patients underwent surgery by this technique. There were no intraoperative complications. The mean best-corrected visual acuity (BCVA) of these patients at 1-month follow-up was 0.5 ± 0.3 (logarithm of the minimum angle of resolution) with 18 of 19 eyes showing one or more lines of improvement in BCVA. X-NIT is a safe, easy, cost-effective, and highly reproducible technique, especially for beginners.

Scleral fixation of intraocular lens (SFIOL) surgery has come a long way since its inception. Conventionally, suture fixation of the intraocular lens (IOL) was practiced. Then, came sutureless SFIOL surgery to avoid suture-related problems.[1] Various techniques exist to secure the exteriorized haptic of the IOL.[12345] However, exteriorization of the haptics in the first place is a challenging step. The conventional handshake technique has a learning curve since it involves intraocular handing over of haptics from one forceps to another. This step becomes particularly difficult in the setting of small pupil or corneal scar. Here, we describe extraocular needle-guided haptic insertion technique (X-NIT), a minimally traumatic, easy, and quick method of exteriorizing the IOL haptics during SFIOL implantation.

Surgical Technique

The surgery is performed under peribulbar or subtenon's anesthesia. A toric IOL marker is used to mark the limbus at two meridia 180° apart depending on the surgical scenario and the choice of location for the main sclerocorneal wound. For purposes of understanding, we describe herein, markings made at 3 and 9 o'clock positions. Limited conjunctival peritomy is done. After adequate cauterization of bleeders, two linear, partial-thickness scleral tunnels of 3 mm length are fashioned on either side (1.5 mm behind and parallel to the limbus) using a 23-gauge microvitreoretinal blade. Both tunnels are created in a counterclockwise direction. A good anterior vitrectomy may suffice in uncomplicated aphakias. A 25-gauge pars plana vitrectomy with limited base dissection is performed in complex scenarios. An infusion system either in the form of an anterior chamber (AC) maintainer with bottle height adjustment or a pars plana integrated vented gas forced infusion system with intraocular pressure compensation is established as per need. A fornix-based conjunctival peritomy is performed spanning the meridian 90° away from the earlier markings at the limbus. A self-sealing sclerocorneal wound of 5.5 mm is made. Herein, we describe the sclerocorneal wound made spanning the 12 o'clock meridian. Two standard 26-gauge (G) needles (13 mm) are bent to 60° near the hub. A customized 2.5 mm × 3 mm silicone stopper is fashioned from the #240 band used for retinal detachment surgery. The first bent 26-gauge needle is pierced through the stopper [Fig. 1]. This needle is then introduced into the ciliary sulcus 1.5 mm behind the limbus, just at the commencement of the scleral tunnel fashioned at the 3 o'clock meridian. Once the needle is visible within the pupillary margin, it is redirected and brought out through the pupil and the sclerocorneal wound. Inadvertent injury to the inner lip of the sclerocorneal wound with the sharp needle is avoided by gently depressing it with McPherson forceps as the needle exits the wound [Fig. 2a]. Approximately 4 mm of the leading haptic of a three-piece polymethyl methacrylate (PMMA) IOL (Aurolens, Aurolab, India) is threaded into the needle using McPherson forceps [Fig. 2b]. The 26-gauge needle is then withdrawn out of the sclerotomy along with the leading haptic [Fig. 2c]. The silicone stopper is now slid over the entire needle shaft and onto the exteriorized portion of the haptic [Fig. 2d]. The needle is withdrawn gently, leaving the exteriorized haptic safely over the sclera with the silicone stopper preventing slippage and intraocular rebound of this haptic during further manipulation of the IOL [Fig. 2e]. Before making the next sclerotomy, the position of the silicon stopper on the leading haptic can be adjusted slightly to give sufficient mobility to the IOL optic and the trailing haptic during its exteriorization. The second bent 26-gauge needle is inserted through the sclera at the 9 o'clock meridian and the trailing haptic is exteriorized [Fig. 2e–g]. We recommend that, after bringing the second needle out through the sclerocorneal wound, the needle be kept flush with the right extreme corner of the wound. This improves ease of threading the trailing haptic with minimum possible globe and haptic distortion. Once the trailing haptic is exteriorized, the silicone stopper on the leading haptic is removed carefully. Both haptics are tucked into the preformed scleral tunnels and the IOL is centered [Fig. 2h]. The sclerocorneal wound can be sutured if needed. Ports/AC maintainer is removed and conjunctival peritomies are cauterized [Videos 1 and 2, Supplementary Digital Content].

Figure 1

A 26-gauge needle bent to 60° and loaded with a silicone stopper (a small piece of #240 band used in retinal detachment surgery) (yellow arrow)

Figure 2

(a) The tip of the 26-gauge needle is brought out through the sclerocorneal tunnel using a McPherson forceps. (b) The tip of the leading haptic of three-piece intraocular lens is threaded into the lumen of 26-gauge needle using McPherson forceps (red arrow). (c) The leading haptic 26-gauge needle complex is withdrawn and exteriorized through the sclerotomy. (d) The silicone stopper is gently slid over the needle shaft to hold the exteriorized haptic. (e) The trailing haptic is threaded in a similar fashion. Note the ease with which this step is performed owing to the silicone stopper (yellow arrow). (f) The trailing haptic 26-gauge needle complex is withdrawn. (g) The trailing haptic is exteriorized. (h) Scleral fixation of intraocular lens is centered after the haptics are tucked into the scleral tunnels

Results

All surgeries were performed by a single surgeon (PB) on 19 eyes of 19 patients. Table 1 shows demographic and preoperative data. The mean best-corrected visual acuity preoperatively was 0.5 ± 0.3 logarithm of the minimum angle of resolution (LogMAR) units which improved by one or more lines postoperatively in all, but one eye that had preexisting corneal pathology. Table 2 summarizes the visual outcome of our patients. Intraoperative complications such as haptic slippage, IOL drop, and intraocular rebound of leading haptic were not encountered. Postoperative complications such as serous choroidal detachment, wound leak, IOL decentration, or retinal detachment were not encountered. Transient corneal edema occurred in three patients, dispersed vitreous hemorrhage in one patient, and postoperative hypotony in another, all of which resolved by the end of the first postoperative week.

Table 1

Patient demography and preoperative data

Table 2

Visual outcome

Discussion

Sutureless SFIOL is the most widely practiced method of managing aphakia without adequate capsular support.[12] Eyes with previous complicated cataract surgery and trauma are the most common causes of aphakia. Such eyes are likely to have had one or more prior surgical interventions and are at an increased risk of developing corneal decompensation, uveitis, glaucoma, and retinal detachment. Hence, the need to minimize trauma during SFIOL surgery.

One of the most challenging steps during SFIOL implantation is exteriorization of haptics. The conventional handshake technique using a pair of intraocular forceps involves intraocular maneuvers that require time and skill to learn. The possible complications during this step include slippage of the haptic, IOL drop, globe collapse, and deformation of the haptic as it exits the sclerotomy. Handshake is particularly challenging in eyes with small pupils or corneal scars. Repeated intraocular manipulations can result in postoperative uveitis, endothelial cell loss, choroidal detachment, and hypotony. All these can result in poor visual outcomes. In our technique, haptic manipulation is completely extraocular which makes it surgically easier, quicker, and much less traumatic.

Our technique has the advantage of a smaller 26G sclerotomy with lesser risk of wound leak, postoperative hypotony, etc., especially because stretching of the sclerotomy with blunt forceps is avoided. Furthermore, tight gripping of the end of the haptic with grasping forceps has a tendency to damage the tip of these PMMA haptics. Since X-NIT does not involve grasping of the haptics, haptic damage is significantly reduced.

Beiko and Steinert[6] have used silicone stoppers from commercially available iris hooks. Threading the haptic into the prepunched hole of these stoppers is rather tedious. Our technique uses a silicone bit that is substantially larger and easier to handle. Since the stopper is pierced by the same 26-gauge needle that snugly holds the haptic, the fit of the stopper over the haptic is tight. The stopper is preloaded on the needle and is simply slid over the haptic. Though optional, this step adds to surgical safety and comfort, reduces dependency on the assistant and is especially useful for beginners.

Takayama et al.[7] have described a method that uses larger (22-gauge) sclerotomies and 24-gauge catheters with guiding needles. However, this technique has intraocular maneuvers. Similarly, Maruko et al.[8] have described a method of exteriorizing haptics using two bent 27-gauge needles. In this technique, the second needle is bent multiple times to facilitate ease of maneuvering through a 3 mm sclerocorneal incision.[8910] However, insertion and withdrawal of this needle through the sclera may pose a challenge due to complex bends. This may carry a risk of haptic slippage intraocularly.[9] Our technique requires only one bend of the needle which is close to its hub. This makes insertion and withdrawal of the needle easy. The haptic does not encounter any bend in its intraluminal course, thus avoiding haptic distortion. Furthermore, Maruko et al. leave the sharp needle tip with the leading haptic intraocularly, in the region of the ciliary sulcus while manipulating the trailing haptic.[9] This poses a significant risk of intraocular haptic slippage and peripheral retinal injury, especially in the hands of a beginner.[10] As it is stressed earlier, in X-NIT, instrument manipulation is entirely extraocular and very safe even for beginners.

The only concern with X-NIT is the need for a 5.5 mm sclerocorneal wound. The X-NIT technique has been tried for foldable SFIOL surgery. However, exteriorization of the trailing haptic is more difficult than with the larger sclerocorneal wound as is the case with the technique described by Maruko et al. Hence, a modification of X-NIT to accommodate for smaller wounds and foldable IOLs is awaited. However, in India and most of the developing world, manual small incision cataract surgery with rigid PMMA IOL is the most frequently performed type of cataract surgery owing to its cost-effectiveness and good visual outcomes. Hence, X-NIT in its present form is a promising alternative to the conventional method of scleral fixation of IOL.

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Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.