Sir,

Scleral thinning and necrosis is a serious complication of pterygium surgery. It is commonly seen after chemotherapy or irradiation to prevent recurrence.1 Scleral patch graft2 or lamellar patch graft with preserved corneosclera3 is usually performed in cases of severe thinning to restore the normal ocular surface integrity. We report two cases of partial thickness scleral thinning (scleral dellen) with thinning of adjacent cornea in one case (corneoscleral dellen), both of which were treated with multilayered amniotic membrane transplantation, suggesting that this surgical procedure can be an alternative treatment in this clinical situation.

Case 1

A 30-year-old female presented to us on 16 October 1999, with complaints of pain and discomfort in the right eye of 1 month duration. She had undergone pterygium excision in that eye 1 month back and the referring physician had noted scleral thinning postoperatively. On examination, she had a visual acuity of 20/20 in the right eye and 20/30 in the left eye. Slit-lamp examination revealed superficial scarring involving the nasal cornea in the right eye. Adjacent sclera showed thinning (Figure 1a) and was avascular. Gentamicin sulphate 0.3% four times a day along with artificial tears were prescribed. The patient underwent multilayered amniotic membrane transplantation over the area of scleral thinning.

Figure 1
figure 1

(a) Diffuse slit-lamp view of Case 1 showing the area of scleral thinning. (b) Diffuse slit-lamp view of the same following amniotic membrane transplantation, 6 weeks after surgery showing amniotic membrane covering the defect.

Full size image

The procedure was performed under peribulbar anaesthesia. Four millilitres of 2% xylocaine with adrenaline and 3 ml of 0.5% bupivacaine with hyalase were injected. Preserved human amniotic membrane was used in the procedure. Human amniotic membrane was prepared and preserved by the standard method.4 The human placenta was obtained shortly after elective caesarian delivery. Serological tests were performed to exclude human immunodeficiency virus, hepatitis virus type B, hepatitis virus type C and syphilis. Under laminar air hood, the placenta was clear of blood clots with sterile Earle’s balanced salt solution containing 50 μg/ml of penicillin, 50 μg/ml of streptomycin, 100 μg/ml of neomycin and 2.5 μg/ml of amphotericin B. The amnion was separated from the rest of the chorion by blunt dissection through the potential spaces between these two tissues and flattened onto a nitrocellulose paper with epithelial/basement membrane surface up. The paper with the adherent amniotic membrane was then cut into different sizes and was stored at −80°C in a 1:1 combination of Dulbecco modified Eagle’s medium and glycerol.

The area of scleral thinning was defined. Three layers of preserved human amniotic membrane were applied over the area of thinning, and anchored to the episcleral tissue with interrupted 10–0 monofilament nylon sutures. Pieces of amniotic membrane were separated from the nitrocellulose paper and placed in the defect with no special care to put either the epithelial or stromal side up. Over this a layer of amniotic membrane with stromal side down was sutured to the adjacent conjunctiva with interrupted 10–0 monofilament nylon sutures. Postoperatively the patient was on topical 1% prednisolone acetate tapered over 3 weeks. This was initiated at three times a day along with 0.3% gentamicin sulphate eye drops 4 times a day for a week and artificial tears. Sutures were removed 2 weeks after surgery. At the last follow-up 6 weeks after surgery, the defect was well covered by the amniotic membrane which had epithelialised (Figure 1b).

Case 2

A 35-year-old female patient reported to us with a diagnosis of scleral and corneal thinning (corneoscleral dellen) following combined phacoemulsification and pterygium surgery in the left eye which was performed 5 days earlier. Antimitotic drugs were not used during surgery. There was a partial-thickness scleral thinning accompanied by thinning of the adjacent cornea. The surrounding sclera was pale (Figure 2a). Ciprofloxacin 0.3% eye drops six times a day along with artificial tears were prescribed. A multilayered amniotic membrane transplant was performed under peribulbar block. The residual tenon’s tissue was excised from the scleral bed. The raw area of the sclera was covered with two layers of amniotic membrane filling the defect; another layer of amniotic membrane was applied with stromal side down and was sutured to the adjacent conjunctiva with interrupted 10–0 monofilament nylon sutures (Figure 2b). Postoperatively the patient was on 0.1% betamethasone sodium phosphate eye drops four times a day, 0.3% gentamicin sulphate eye drops four times a day and artificial tears six times a day. The sutures were removed after one week. Topical steroid medication was tapered and the patient was continued on artificial tears. At last follow-up, one month after surgery the eye was quiet and the surface had epithelialised.

Figure 2
figure 2

(a) Diffuse slit-lamp view (of Case 2) showing partial thickness scleral thinning with thinning of adjacent cornea. (b) Diffuse slit-lamp view of the same patient, 3 weeks after surgery showing amniotic membrane covering the area of scleral or corneal thinning.

Full size image

Comments

Amniotic membrane, the innermost layer of placental or fetal membrane, consists of a thick basement membrane and an avascular stroma. The various observed effects of amniotic membrane after transplantation include rapid epithelialisation, return of normal epithelial phenotype,4 reduced inflammation,5 reduced vascularisation and reduced scarring. The amniotic membrane acts as a substrate for surface epithelialisation.

Kruse et al5 reported the use of multilayered amniotic membrane transplantation for reconstruction of deep corneal ulcers.5 They found this procedure useful in treating deep corneal ulcers and even descemetoceles. The stromal thickness was maintained even when the transplanted layer of amniotic membrane had gradually been dissolved. This study led us to surmise that multilayered amniotic membrane could allow surface reconstruction in partial-thickness scleral necrosis and corneal thinning as it is said that in a less severe case of corneoscleral thinning, even a conjunctival graft alone without lamellar corneal or corneoscleral or scleral reinforcement is sufficient to fulfil the requirement of normal healing.6,7

Chen et al reported amniotic membrane transplantation for severe neurotrophic corneal ulcers in 15 eyes. More than one layer of amniotic membrane was applied in six of these eyes. Handa et al recently reported use of multilayered amniotic membrane transplantation for the treatment of deep ulceration of the cornea and sclera. The authors performed multilayered amniotic membrane transplantation in severe ulcers to achieve the goals of collagen layer supplementation, basement membrane reconstruction, promotion of epithelialisation and wound healing. Two of these patients had scleral ulcers because of pterygium and foreign body. In these cases, the ulcer was filled with autotenon’s capsule tissue. The second amniotic membrane was transplanted as a basement membrane (amniotic membrane graft). Amniotic membrane was placed in the ulcer with epithelial side up and secured with 10–0 nylon sutures. The third amniotic membrane was transplanted as a cover (amniotic membrane patch) with 10–0 nylon or 8–0 vicryl sutures. These cases epithelialised with conjunctiva, one case after 10 days and the other after 27 days. The sclera regained its original thickness.

In the two cases reported, the surgical details available did not suggest the use of antimetabolites during surgery or irradiation. The eyes were quiet and scleral defect was filled well with the amniotic membrane after surgery. The scleral thickness was regained. The surface had epithelialised well. We feel that in these cases of partial scleral thinning we achieved our objectives of filling up the scleral defect and adequate surface reconstruction. We propose this alternative technique as it is a simple procedure compared to scleral or corneoscleral patch grafts. Unfortunately, the surgical follow-up of the cases is too short to comment on the long-term usefulness of the procedure in this situation.

To conclude, multilayered amniotic membrane transplantation is a useful alternative choice to scleral or corneoscleral lamellar patch graft for scleral thinning following pterygium surgery. Further studies with long follow-up are warranted to evaluate the efficacy of the procedure in this clinical situation.