Sir,

Emergency penetrating keratoplasty has been associated with a lower rate of corneal graft survival, and a higher rate of immune reactions compared to scheduled normal risk keratoplasty.1 High-risk penetrating keratoplaty has a success rate of 50% compared to 90% for a low-risk penetrating keratoplasty.2 We wished to evaluate our experiences of emergency keratoplasty in a single tertiary ophthalmic care unit in West Scotland.

A retrospective case series is presented of 15 eyes in 14 patients who received therapeutic keratoplasty for corneal perforation or impending perforation, from January 2014 to December 2016. Anatomical success was defined by eradication of infection and or preservation of the globe. Corneal graft survival was defined by the presence of a clear graft at last follow up.

Mean age was 61 (±14) years. Indications for emergency keratoplasty were infectious corneal melt which was unresponsive to medical management in 8 eyes, non-infectious immunological corneal melt in 5 eyes and trauma in 2 eyes. The follow up period ranged from 7 to 43 months, mean follow up of 22 months. The mean diameter of the donor corneal disc was 8.2 (±1.1) mm, 0.5 mm larger than the recipient bed.

There was anatomical success in 14 of 15 eyes. Evisceration was required for one eye, due to recurrent non- infectious corneal melt. The corneal graft survived in 9 of 15 eyes. Five eyes underwent repeat keratoplasty.

The corneal graft survival rate for 2 eyes following trauma was 50%, at follow up of 27 and 43 months. One graft failed at 37 months due to further trauma. The graft survival rate for the 8 patients with infective corneal melt was 62.5%, with mean follow up of 17 months. Mean time to graft failure was 8 months. Interestingly 2 of the 3 patients who experienced graft failure, also had underlying immunological conditions (Table 1).

Table 1 Patient demographics
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Five patients had non-infectious immunological corneal melt. The associated systemic conditions are detailed in Table 1. The corneal graft failed in all these patients. Three failed due to infection, and two failed due to immunological melt. The mean time to failure was 6 months. All five patients were prescribed systemic immunosuppression (Table 1).

Cataract and secondary glaucoma were the most common complications (Table 2). 5 patients required repeat penetrating keratoplasty, 2 patients required 3 further penetrating keratoplasties (Table 2).

Table 2 Penetrating keratoplasty survival and complications
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There is relative paucity of data in the literature describing emergency penetrating keratoplasty. A recent study found that infectious keratitis lead to 74% of emergency keratoplasty, with perforation evident in 53% of cases.3 In this group, infection was the major indication for an emergency keratoplasty followed by immunological melt. Judicious use of pre, intra and postoperative antibiotic usage is crucial for graft survival in infectious aetiology.

Despite newer immunosuppressants, the outcome for immunological melt is dismal. Systemic immunosuppression has been shown previously to improve corneal graft survival, due to improved control of the underlying systemic disease.1

Larger multicentre studies are needed for better understanding variables affecting corneal graft outcome in an emergency context.