Anterior Lamellar Keratoplasty over Penetrating Keratoplasty for Optical, Therapeutic and Tectonic IndicationsMarcus Ang, MBBS, MMedJodhbir S Mehta, FRCOphthAnshu Arundhati, FRCSEd Donald Tan, FRCOphth

The authors have no financial interest.

Singapore National Eye Centre

PurposeRepeat penetrating keratoplasty (PK) is becoming a leading indication for corneal grafting.

However, the survival graft rates and visual outcome is often poor compared to the initial PK.

Anterior lamellar keratoplasty (ALK) over the previous PK may be considered as an alternative to a repeat PK in selected patients.

We present a series of patients who underwent an ALK over a PK, for a variety of optical, therapeutic and tectonic indications requiring anterior stromal replacement of the previous penetrating graft.

MethodsWe reviewed all patients who underwent ALK after an initial PK in Singapore National Eye Center (SNEC) between January 1991 and May 2008.

Data included patient demographics, ophthalmic history, and indications and details of surgery, preoperative and postoperative Snellen visual acuity (VA) with refraction.

Outcome measures were: Final VA, Graft failure (ALK, PK or both) - defined as an irreversible loss of central graft clarity from any cause, irrespective of the level of VASuccessful restoration of tectonic integrity in tectonic indications Eradication of infection in therapeutic cases

Surgical Techniquesa) Manual Deep Anterior Lamellar Keratoplasty

(DALKm) (n= 7). This was performed using a previously described technique.1

b) Automated lamellar therapeutic keratoplasty (ALTK) (n = 1) A modified two-stage ALTK using a previously described technique was performed.2

The lamellar grafts were centered on the previous PK in 6 cases, or on the visual axis (2 cases) in those with decentered PK.

Five of 8 eyes had oversized ALK grafts compared to PK [Mean 0.85mm (0.50-1.50mm)] 1. Parthasarathy A, Tan D. Simplified technique for deep lamellar keratoplasty.

Cornea. 2008 Apr;27(3):387-8;2. Tan DT, Ang LP. Modified automated lamellar therapeutic keratoplasty for

keratoconus: a new technique. Cornea. 2006 Dec; 25(10): 1217-9.

ResultsEight eyes of 8 Asian patients (6 females and 2 males) with a mean age of 53 years (range 15-84).

Mean interval time between the initial PK and subsequent ALK was 72 ± 64 months. Mean follow-up duration after ALK was 27±22 months.

Final BCVA improved in 5 eyes, with gain of 2 or more lines of BCVA (range, 2–6 lines) and unchanged in 2 eyes after the subsequent ALK.

Mean preoperative logMAR BCVA was 1.52±0.25 improved to 0.87±0.26 postoperatively (P= 0.032).

A: Patient 1 with recurrence of granular dystrophy 21 years post-PK;B: Patient 1, two months postoperatively following ALTK on previous PK. C: Patient 2 with candida infection 1 month post-PK, on medical therapy for 18 days. D: Patient 2, 1 month postoperatively following DALKm on previous PK, with clear graft.

A: Patient 5 with corneal scarring from previous infective keratitis, 13 years post-PK B: 4 weeks post-DALKm on previous PK, showing temporary endothelial dysfunctionC: 3 months postoperatively complicated by candida infection- infiltrate at 7 o’clock. D: 3 months postoperatively following DALKm and graft repositioning, and intra-corneal amphotericin injection.

DiscussionIn our series of patients who had undergone an ALK following a PK, patients managed to achieve successful visual rehabilitation without the need for a repeat PK.

3 of 8 (38%) eyes managed to attain post-ALK BCVA comparable to BCVA post-PK (Best vision post-PK before disease recurrence or infection) with most (5 of 8 eyes) patients having improved post-ALK BCVA.

Advantages and disadvantages of of ALK over PK versus a repeat PK is discussed in Table 2.

The ALTK technique described can reduce irregular astigmatism due to scarring/folds at the donor-host corneal interface.

Table 2: Discussion on advantages of performing ALK over PK as compared to repeat PK

Advantages Disadvantages

Poorer graft survival in repeat PK as compared to an ALK over PK procdure due to increased allograft rejection

ALK surgery is uncommonly performed, is technically more challenging and has a steep learning curve.

‘Lamellar grade’ cornea donor tissue may be used, as opposed to PK grade tissue (lamellar grade corneas here are defined as optically clear donors but with poor endothelial cell counts precluding usage for PK surgery).

There is the risk of intra-operative Descemet’s membrane rupture, and perforation rates as high as 30 percent have been reported following DALK, requiring conversion to PK.

It can also be an option in tectonic cases (as described in our patients who developed a corneal melt and perforation secondary to neurotrophic keratitis, or Steven Johnson Syndrome)

Endothelial cell loss of up to 25% can still occur post-DALK.

ConclusionALK may be a viable and safer option for a variety of optical, therapeutic and tectonic indications as compared to a repeat PK in a select group of patients.

Thank you

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