Diffuse corneal involvement and cicatrization of the uveal tissue along with high IOP result in a large ectatic area. Multiple causative factors have been noted in literature, the common ones being keratitis and congenital malformations, with sporadic reports of disorders such as neurofibromatosis and sarcoidosis.

The surgical options for anterior staphyloma and similar diffuse corneal lesions include conventional keratoplasty, overlay grafts, and partial or full thickness sclerokeratoplasty. However, anterior staphyloma is associated with additional problems other than corneal ectasia The lens is often cataractous with compromised zonules, which has to be taken care of at the time of the surgery. In addition, staphylectomy leads invariably to loss of iris tissue, creating an iatrogenic aniridia. Therefore, an ideal transplant for an anterior staphyloma or a similar diffuse anterior pathology should take care of these issues.

We suggest a new, single-sitting surgical technique that can be used to treat a malformed anterior segment and to transplant a new biosynthetic prosthetic assembly simulating the anterior segment.

Surgical technique

Under general anesthesia, the maximum horizontal and vertical diameters of the staphyloma at the base were measured. This served as a measure of the size of the graft. The bioprosthetic implant was designed by Dr. Jacob. It consisted of two parts. The biological part was fashioned out of a cadaveric whole globe, and the synthetic part consisted of an aniridia IOL. We used the OV lens style ANI5 aniridia implant (Intra Ocular Care Pvt. Ltd.). It had an overall length of 12.75 mm and an optic diameter of 5 mm to 9.5 mm. The IOL power was calculated to be 24.5 D based on the fellow eye power.

A 3 mm by 3 mm area on the sclera was marked 180° apart in the horizontal axis. Two partial-thickness limbal-based scleral flaps 3 mm in size were created (Figure 2a). Two straight sclerotomies were made with an 18-gauge needle 1.5 mm from the limbus under the existing scleral flaps. After this, a scleral incision was made at the pre-marked area, and it was extended gradually along the preplaced marks with corneoscleral scissors. The dissection was carried out superior to the uveal tissue so as to create a plane between the choroid and the sclera (Figure 2b). Once the entire 360° dissection was completed, cyclodialysis was induced to separate the uveal tissue from the dissected corneoscleral button. After completion of cyclodialysis, the corneoscleral button was ensured to be free of any adhesion and lifted up from the globe. The button was then inverted, and the endothelial surface was coated with viscoelastic.

Figure 2a: Scleral flaps are created on the donor eye.

Figure 2b: Sclerocornea is taken from donor eye.

The corneoscleral graft was placed concave side up (endothelial side up). The aniridia IOL was held with McPherson forceps in one hand (Figure 2c). End-gripping 25-gauge microrhexis forceps (MicroSurgical Technology) were passed through the sclerotomy incision of the right side with the other hand. The tip of the leading haptic was grasped with the microrhexis forceps and pulled through the sclerotomy following the curve of the haptic. The haptic was then externalized under the inferior scleral flap. The other haptic was also externalized through the diametrically opposite sclerotomy under the scleral flap. The bioprosthetic assembly was thus completed and gently flipped to convex side up position (Figure 2d). The externalized haptics were directly visible now, and they were adjusted slightly to maintain IOL centration. The bioprosthetic assembly thus consisted of donor cornea and sclera and a simulated iris and lens (aniridia IOL).

Figure 2c: Aniridia IOL haptics are externalized.

Figure 2d: Bioprosthetic graft is complete.

Host dissection

A small incision was created in the uninvolved area temporal to the staphylomatous cornea. It was extended 360° with corneoscleral scissors, ensuring that the dissection removed the entire staphylomatous area along with a thin rim of normal tissue (Figure 2e). The lens, which was cataractous, was removed by open sky lensectomy, leaving an intact posterior capsule for support (Figure 2f).

Figure 2e: Anterior staphylectomy is done.

Figure 2f: Lensectomy is performed.

The bioprosthetic assembly was now placed on the host, and one nasal 8-0 monofilament nylon suture was placed to secure it at the graft-host junction (Figure 2g). The donor scleral rim was now trimmed by freehand dissection to match the host size. Twenty interrupted 8-0 monofilament nylon sutures were placed to secure the graft over the host. Vitrector-assisted posterior capsulotomy and anterior vitrectomy were performed, and the remaining sutures were applied.

Figure 2g: Bioprosthetic graft is sutured onto recipient eye.

Glued aniridia IOL

With a 22-gauge needle, a scleral tunnel was created along the curve of the exteriorized haptic at the edge of the scleral bed of the flap. The haptic was tucked into this tunnel. A similar tunnel was created in the complementary area on the other side, and tucking was performed. Fibrin glue (Tisseel, Baxter) was reconstituted. The reconstituted fibrin glue was injected through the cannula of the double syringe delivery system under the superior and inferior scleral flaps. Local pressure was applied to the flaps for 30 seconds to allow for polypeptide formation. The host conjunctiva was advanced to cover the suture line and was apposed near the cornea with fibrin glue (Figure 3).

Postoperatively, the child was started on eye drop prednisolone phosphate, eye drop moxifloxacin 0.5%, eye drop cyclosporine 2% and preservative-free tear substitutes. The child was following light with the operated eye, and there was much improved lid closure and cosmesis. On examination under anesthesia, the cornea was clear with all the sutures buried under the conjunctiva.

Figure 3: Postop at the end of surgery.

Discussion

Fibrin glue-assisted transscleral fixation of the IOL has been performed successfully as a standalone procedure or as a combined procedure. The results of the same, along with keratoplasty, have been encouraging, providing unique benefits over suture-fixated IOL. These benefits include lesser manipulation leading to decreased open sky time, increased stability of the IOL, lesser pseudophakodonesis, and no suture- or knot-related complications (degradation and slippage). A suture-fixated IOL assembly has four joints (one each at the suture-haptic junctions and one each at the haptic-optic junctions). The amount of rotational and oscillatory freedom is much higher at the suture-haptic junction compared with that at the more rigid optic-haptic junction. In contrast, a glued IOL is stabilized by exteriorizing the haptics, and there is a single PMMA optic-haptic configuration on both sides, which leads to much reduced rotational and oscillatory freedom. The larger diameter and the higher weight of the aniridia IOL also make a sturdier transscleral haptic fixation as a procedure of choice. In addition, reduced pseudophakodonesis with the glued IOL may lead to reduced uveal chaffing and lesser pigment release.

Aqueous drainage can be compromised in these patients because of the disturbed trabecular meshwork. As we performed anterior vitrectomy, the anterior vitreous face was not intact, and there was a reasonable chance of aqueous seepage around the IOL, with an uveoscleral outflow. This might have resulted in normal IOP in this case. However, we do not rule out the possibility of a filtering procedure in such cases in future.

Summary

To conclude, this article demonstrates the surgical feasibility and postoperative outcomes of this biosynthetic implant in cases of diffuse corneoscleral pathology. Longer follow-up and a larger prospective study will be required to assess the results in similar patients, in which any of the currently established conventional procedures fall short of a satisfactory rehabilitative and anatomical outcome.

Amar Agarwal, MS, FRCS, FRCOphth, can be reached at Dr. Agarwal’s Eye Hospital and Eye Research Centre, 19 Cathedral Road, Chennai 600 086, India; fax: + 91-44-28115871; e-mail: dragarwal@vsnl.com; Web site: www.dragarwal.com.