Scleral Fixation of a Subluxated or Dislocated Lens

Subluxation and dislocation are known complications of foldable IOL implantation following phacoemulsification. Although the AcrySof single-piece IOL (Alcon Laboratories Inc., Fort Worth, Texas), is often implanted after phacoemulsification,¹ complications management for this IOL has not been well addressed in literature.

EXAMINING THE OPTIONS
When a posterior chamber IOL is malpositioned, a surgeon has several options including (1) observation, (2) miotics, (3) repositioning, or (4) explantation and exchange of the IOL.² Each offers its own advantages and disadvantages. Lens explantation and exchange, for instance, requires a larger incision and is more traumatic to the cornea and iris. It also involves greater risk of vitreous loss, postoperative astigmatism, and endophthalmitis. Additionally, the placement of a single-piece AcrySof into the ciliary sulcus causes pigment dispersion, pigmentary glaucoma, uveitis, and iris chafing.^3-6

Transscleral suture fixation has been used for secondary implantation of single-piece foldable acrylic IOLs (eg, AcrySof SA60AT, AcrySof SN60AT) placed through a small clear corneal incision. This is a reasonable technique for lens implantation in eyes with an absence of capsular support.^7,8 Different transscleral suturing techniques for posterior chamber IOLs have also been described in literature.^9-30 Haptics of transsclerally fixated or sutured lenses have been placed at the ciliary sulcus^13,19 through incisions in the pars plicata²⁶ and as far posteriorly as the pars plana.^27-29 Literature also describes temporarily externalizing the haptic of a dislocated IOL through a clear corneal incision during scleral fixation.^26,27

The ab externo suture loop-retrieval and scleral technique can be used to anchor the haptic and reposition decentered, subluxated, or dislocated IOLs. In one study, four malpositioned AcrySof single-piece SA60AT IOLs were successfully repositioned with this technique.³¹ Incidentally, this is the only description in literature that we have found of any technique to reposition SA60AT IOLs.

In another technique, an intravitreal cow hitch (girth) knot has been used to secure the haptic of a posteriorly dislocated IOL.^32,33 This knot, however, requires multiple intraocular maneuvers and instrumentation.

OUR EXPERIENCE
We used an ab externo technique for scleral fixation of dislocated single-piece AcrySof lenses. We began by retrieving the IOL into the anterior chamber and temporarily externalizing each haptic through a corneal paracentesis. Then, we created a cow hitch knot to secure the haptics. This technique takes advantage of the design and material of the haptics and can be easily performed by anterior segment surgeons.

Often, the subluxated or dislocated lens may be partially or entirely visible in the pupillary area (Figure 1). When this is the case, the conjunctiva is dissected in diametrically opposite areas, and the sclera is bared—avoiding the 3- and 9-o'clock positions. Two 2 x 2 mm rectangular scleral flaps are then made 1 mm posterior to the surgical limbus. In eyes receiving intervention in the early postoperative period, the original paracentesis is gently opened with a 1-mm spatula. Alternatively, two paracentesis (ie, P1 and P2) are made approximately four clock-hours apart (Figure 2).

The anterior chamber is filled with an ophthalmic viscosurgical device and topped off throughout the procedure. When the IOL is subluxated or dislocated in the anterior vitreous, it is brought into the anterior chamber bimanually using a Hirschman hook and spatula (Figures 3 and 4). The flexible loops of the IOL prevent damage to the pupillary margin or iris. Bimanual anterior vitrectomy is then performed to remove any capsular remnants and vitreous strands.

Under one of the reflected scleral flaps, a straight needle mounted with a 10-0 polypropylene suture is passed transsclerally, 1.5 mm posterior to the limbus and perpendicular to the sclera. A 26-gauge hypodermic needle is then introduced through P1, diametrically opposite to the entry point of the straight needle. This needle is used to dock and guide the straight needle out through P1 (Figures 5 through 7). These needles may pass the IOL either anteriorly or posteriorly, depending on accessibility, mydriasis, and haptic orientation.

Under the same scleral flap, a second 26-gauge needle is passed 1 mm adjacent to the straight needle's entry point. The straight needle is retraced through the paracentesis and retrieved by docking it into the second needle (Figure 8), creating a loop of 10-0 polypropylene outside of P1 (Figures 9 and 10).

The Hirschman hook is used to exteriorize the haptic adjacent to P2 (Figures 11 and 12). The hook is then passed through P2 to catch one of the limbs of the polypropylene loop and draw it out (Figures 13 and 14). Next, a cow hitch knot is made by folding the loop over the suture and drawing out the limbs of the suture through the loop itself (Figures 15 through 18). The haptic is passed through the loop, and the knot is tightened. The haptic is reposited into the anterior chamber by pushing it in with a Hirschman hook (Figure 19) or by dialing it in and then tucking it under the iris with the hook. Simultaneously, the limbs of the polypropylene suture are steadily pulled and drawn through the sclera. A temporary knot is then created, before the second haptic is secured in the same manner.

The tension on both the transscleral sutures may be adjusted to avoid decentration or tilt, before each side is knotted with multiple throws. Finally, the scleral flap is reposited, and the conjunctiva is closed.

RESULTS
We have performed this technique in three eyes, that were referred to us within 2 weeks of surgery for the management of postoperatively detected malpositioned lenses. Malpositioning occurred for various reasons: In two eyes, the surgeon attempted to place the IOL in the bag, despite a posterior capsule tear. In another eye, the surgeon attempted dialing the haptics away from the tear in the capsulorrhexis.

One eye had intraoperative hyphema from an iris injury, caused by a change in the straight needle's angle of entry. This was controlled by raising the intraocular pressure (IOP).

Two weeks postoperatively, one eye developed cystoid macular edema, which resolved within 3 months after a regimen of topical steroids and antiinflammatory agents. No eyes, however, showed evidence of pigment dispersion on the lens surface or anterior chamber angle. Additionally, IOP remained within a normal range. At 13 months, all eyes had well-centered lenses and a BCVA of 20/20. Furthermore, no eyes showed evidence of suture erosion, endophthalmitis, or dislocation.

DISCUSSION
The contact of a sharp-edged haptic (eg, single-piece AcrySof) to the posterior surface of the iris is associated with pigment dispersion, uveitis, and glaucoma.^3,4 It is not recommended, therefore, to merely place this lens into the sulcus, primarily or secondarily, even in the presence of adequate capsule and zonular support.^5,6 We believe better solutions include explantation and exchange or repositioning the same lens by scleral fixation.

Anatomic studies have shown that the average ciliary sulcus is located 0.5 to 1 mm posterior to the limbus.³⁴ Securing the IOL by placing transscleral sutures approximately 1.5 mm posterior to the limbus ensures that the IOL is placed into the posterior ciliary sulcus and is impinged on the pars plicata. This eliminates the possibility of contact between the haptic and iris.

Surgeons have also used the ab externo suture loop-retrieval and scleral fixation technique for a malpositioned single-piece AcrySof with some success.32 There are several difficulties, however, that discouraged us from using this technique including the (1) possibility of the haptic slipping, (2) difficulty of the technique in the presence of a freely mobile IOL, (3) manipulations that would be required, and (4) complications that may arise if the pupil became small and obscured the haptics.

Our technique takes advantage of the unique design and material of the haptic of the AcrySof because:

• The knob at the tip, the square edges, and the tacky nature of the haptic material prevent the cow hitch knot from slipping;

• The single-piece stable-force design (with flexible haptics) allows externalization of the haptic without damaging the haptic-optic junction or haptic;

• The haptic can be bent into a knuckle while externalizing it, without fear of damage;

• The one-piece design at the haptic-optic junction and the ability of the haptic to be straightened compensates for any disparity in the overall diameter of the IOL and the sulcus-to-sulcus diameter;

• When tied outside the eye, the cow hitch knot, compared with intravitreal knotting in a closed eye, does not require specialized maneuvers or instruments;^31,33

• The knot can also be tightened or loosened to adjust its position on the haptic; and

• Anchoring the haptics with sutures in a short-diameter IOL eliminates the possibility of anteroposterior vaulting or movement of the IOL parallel to the iris plane.

Suven Bhattacharjee, MS, DNB, is a Consultant Eye Surgeon to Apollo Gleneagles Hospital and is in private practice at Complete Care Eye Clinic, in Kolkata, India. Dr. Bhattacharjee states that he has no financial interest in the products or companies mentioned. He may be reached at suvenb@gmail.com.

Arup Chakrabarti, MS, is in private practice at Chakrabarti Eye Care Centre, in Trivandrum, India. Dr. Chakrabarti states that he has no financial interest in the products or companies mentioned. He may be reached at tvm_meenarup@sancharnet.in.

Abhijit Ghosh, MS, is in private practice at Aurobindo Netralaya, in Kolkata, India. Dr. Ghosh states that he has no financial interest in the products or companies mentioned. He may be reached at anetralaya@yahoo.co.in.

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