Case 23a

by Dr.Chua

A 53-year-old presented with a left red eye and normal vision in mid-December,2005. Examination revealed peripheral marginal keratitis and corneal thinning. Apart from non-insulin dependent diabetes mellitus, he had no history of note. A series of blood test including auto-immune screening was negative. He responded to topical steroid and antibiotic. A course of oral doxycycline was also given for its anti-collagenase activity to prevent perforation. During the course of treatment he developed asymptomatic calcification plaques at the sites of the corneal thinning but otherwise the eye was quiet. He returned in mid-March, 2006 with a sudden but painless drop in vision from 6/6 to CF. Examination revealed breakdown of the calcification plaque with iris prolapsed and a shallow anterior chamber (Figure 1).

Figure 1. Left peripheral temporal corneal perforation with iris prolapsed and

peripheral corneal thinning with calcifications.

An emergency operation was performed on the same day, the iris was excised to reveal a corneal perforation measuring 2.5mm in diameter. As corneal graft required several days of ordering from oversea, we patched the eye with amniotic membrane (which we kept in store as air-dried sheet from the Tissue Bank of the Universiti Sains Malaysia). The air-dried sheet was soaked in normal saline for five minutes for rehydration and cut to fit. Multiple layers of amniotic membrane were first placed over the perforation and a piece of amniotic membrane that folded over itself was sutured to the cornea and beneath the surrounding conjunctiva (after performing peritomy around the site of the perforation).

Figure 2. Appearance of the eye at 3-day post-amniotic membrane graft. The anterior

chamber remained flat though not leakage is observed around the edge of the patch.

Post-operatively, the vision remained poor at 6/60 with a flat anterior chamber. No leakage was seen but the anterior chamber remained shallow after 4 days. A bandage contact lens was applied at this stage but without effect on the depth of the anterior chamber. A repeated amniotic membrane graft was performed one week after the initial repair. This time the rim of calcification was removed and two double-layered of amniotic membrane were sutured to the cornea and under the surrounding conjunctiva after patching the perforation with new layers of amniotic membrane. To avoid perforation of the adjacent nasal calcification plaque, a double-layered of amniotic membrane was also sutured over it.

Despite the second operation, the anterior chamber remained flat after four days even with a contact lens. A tectonic corneal graft appeared to be the only option. The Lion's Club in Kuching kindly agreed to donate a corneal sclera button and a donor cornea was obtained from Sri Lanka in four days. Repeated operation was carried out two weeks from the initial perforation. The amniotic membrane over the wound was removed and the cornea edge and base were cleared of the calcification plaque. Following the removal of the plaque, the area of perforation measured 4.5 mm in its widest diameter. A corneal sceral button measuring 7 mm was punched out and sutured to the cornea and the sclera. Conjunctival flaps were sutured to the edge of the limbus to cover the donor sclera.

Figure 3. Two days after localized penetrating keratoplasty, the anterior chamber was formed.

The nasal peripheral corneal thinning was covered with a double layer of amniotic

membrane graft.

Post-operatively, the anterior chamber was reformed and the vision improved to 6/24 with pin-hole. He was treated with topical steroid, gentamicin, artificial tear and oral doxycycline.

a. Apart from amniotic membrane and a penetrating keratoplasty, what are the other techniques which can be used in tectonic procedures?

Keratoplasty either lamellar or penetrating is the preferred procedure for corneal perforation. However, when corneal graft could not be obtained in time, some temporizing measures are required to close the perforation to prevent loss of the eye due to infection. Alternative tectonic procedure may also allow healing of the underlying condition during medical treatment and allow definitive surgery to be performed under more optimal conditions once inflammation or infection has been controlled.

 

The various measures include¹:
 

i. tissue adhesive such as cyanoacrylates; this is useful only for small perforation and contact lens is required to cover the area of application.

 

ii. therapeutic contact lenses or collagen shields, again only effective for small perforation.

 

iii. patch grafts such as conjunctival flap, scleral flap (see figures below) or amniotic membrane graft which may be effective for moderate size perforation.

b. How successful is amniotic membrane in tectonic procedure?

The success of amniotic membrane in managing corneal perforation appears to be related to the size of the perforation. Rodriquez-Ares et al² found a success rate of 73% in using AM in managing corneal perforation (11/15 cases), however in perforation greater than 3 mm the success rate is lower (1/4 cases). Hick et al³ found that if AM is performed in conjunction with fibrin sealant, the success rate is increased for perforation up to 3 mm than AM alone (92.9% versus 73.7%).

 

Although AM alone was unsuccessful in restoring the integrity of the anterior chamber in this case, it was successful as temporizing measure until a definitive procedure with the available material became available.

Reference:

1. Daniel M. Albert. Ophthalmic Surgery: Principles and Techniques. Chapter 10: Tectonic procedures. Blackwell Science.

2. Rodriguez-Ares MT, Tourino R, Lopez-Valladares MJ, Gude F. Multilayer amniotic membrane transplantation in the treatment of corneal perforations. Cornea. 2004 Aug;23(6):577-83.

3. Hick S, Demers PE, Brunette I, La C, Mabon M, Duchesne B. Amniotic membrane transplantation and fibrin glue in the management of corneal ulcers and perforations: a review of 33 cases. Cornea. 2005 May;24(4):369-77.