NEW TECHNIQUE

Subluxated cataracts and IOLs are managed effectively by many of the current devices/techniques available. Smaller subluxations, less than one quadrant are managed by implantation of a capsular tension ring (CTR) whereas subluxations larger than one quadrant need scleral fixation of the capsular bag. This has been achieved effectively in the past by various sutured segments/rings available. However, all of these require suturing of the device to the scleral wall.

The inherent disadvantages of techniques involving suturing are the longer time taken, the greater level of skill required for suture fixation and the need to pass long and thin needles across the anterior chamber, all of which make surgery challenging. It also leads to risk of suture-related complications such as suture degradation, knot exposure, knot unravelling, delayed onset subluxation and so on. 9-0 prolene and Goretex have been used in an attempt to address these suture-related problems, however, they still leave issues related to the challenging nature of surgery unaddressed.

Capsule hooks/retractors have also been used during phacoemulsification for intra-operative support to the bag. They are introduced via paracenteses to engage the rhexis rim and hold the bag fixed to the limbus during cataract extraction and are then replaced by a sutured device for continued IOL centration and stabilisation in the postoperative period. However, this makes surgery a two-step procedure, having to again perform a set of complicated manoeuvres for suturing in the device immediately after having removed the subluxated cataract.

Glued capsule hook/retractor

This is a new technique that I started for eliminating complicated manoeuvring and increasing ease and rapidity of surgery in subluxated cataracts. This technique avoids the need for suturing a device by continuing to utilise in the postoperative period, the same hook that is used during cataract surgery to centre the bag. The technique is as follows:

The capsular hook is modified by straightening out the bend on its shaft and a new 90 degree bend given to the shaft. A lamellar scleral flap is created centred on the dialysis as done for sutured devices. Next, a 20-gauge needle is used to create a sclerotomy under the scleral flap. The needle is passed vertically until it crosses the plane of the posterior capsule of the lens and then directed horizontally. This prevents the needle from touching the posterior capsule. A rhexis is then created centred on the anterior capsule. The capsular hook is inserted through the sclerotomy between the iris and the anterior capsule and used to engage the rhexis.

Pushing the silicone stopper down centres and holds the bag in place. Additional capsular hooks may be passed trans-limbally if greater support is needed for intra-operative manoeuvres. In case of larger subluxations additional trans-scleral hooks may be used evenly spaced around the limbus to obtain even support and good centration. Once the bag is thus stabilised, cortical cleaving hydrodissection is done followed by insertion of a standard CTR. This is because though the capsular hooks attach the capsular bag to the sclera, they do not expand the fornices, hence a CTR is mandatory. Nucleus extraction and cortical aspiration are carried out following standard precautions taken for a subluxated cataract. The IOL is then injected into the bag.

Once this is done, all trans-limbal hooks are removed and the trans-scleral hook/hooks fixed into their final position. For this, a 26-gauge needle is used to make an intra-scleral Scharioth tunnel at the edge of the scleral flap. The hook is then held firmly with a needle holder at the sclerotomy and the silicone stopper removed. The haptic of the hook is cut to the desired length and is tucked into the intra-scleral tunnel. The degree of centration of the IOL is adjusted by adjusting the degree of tuck of the haptic. Vitrectomy is done under the flap and both the scleral flap and conjunctiva are glued down using fibrin glue (see figures A-F).

Many advantages

This technique, therefore, allows sutureless trans-scleral fixation of the hook and thereby the bag to the sclera. The advantages of this surgery are many. It removes the element of suturing from the surgery which by itself removes technical challenges associated with passing long and thin needles across the anterior chamber, achieving centration etc. Surgery becomes easy and rapid. The hook is easy to pass into the anterior chamber trans-sclerally. It is easy to find the plane between the iris and the anterior capsule by inserting the hook at the correct angle and also if required by instilling viscoelastic under the iris in the affected quadrant and thereby creating space between the iris and the anterior capsule. If required, the hook may also be exteriorised through the sclerotomy in an ab-interno technique by introducing the haptic of the hook through the corneal incision into the jaws of a microforceps that is passed in through the sclerotomy.

The hook may be created from various materials of which PVDF and polyimide may be most suitable. This gives longevity to the scleral fixation and also does away with long-term issues related to suture degradation that are associated with 10-0 prolene and other sutures. The stability of the IOL is better than with sutured devices as it is not a suture but rather the intra-scleral tuck of a significant portion of the haptic that fixes the bag trans-sclerally. For the same reason, pseudophakodonesis is also likely to be less with the glued capsule hook technique rather than with sutured devices. Centration is easy to achieve by adjusting the degree of tuck of haptic into the tunnel and one is not locked down into position as with sutured devices on tying down the suture.

To conclude, glued capsule hook is a new technique for sutureless trans-scleral fixation of the capsular bag and its contents and has significant advantages over other presently used techniques.

* Dr Soosan Jacob is a senior consultant ophthalmologist at Dr Agarwal's Eye Hospital, Chennai, India and can be reached at: dr_soosanj@hotmail.com. She has a patent pending for modified versions of the glued capsular hook.