"Management of Advanced Keratoconus with Deep Anterior Lamellar Keratoplasty (DALK).” Rohanah A., Thiageswary U. Department of Ophthalmology, Hospital.

"Management of Advanced Keratoconus with Deep Anterior Lamellar Keratoplasty (DALK).”

Rohanah A., Thiageswary U. Department of Ophthalmology, Hospital Kuala Lumpur

THE AUTHORS HAVE NO FINANCIAL INTEREST TO DISCLOSE

Introduction

Keratoconus is disorder characterized by progressive corneal steepening, with eventual corneal thinning, induced myopia, and both regular and irregular astigmatism.

Advanced keratoconus leads to inadequate acuity despite of glasses or contact lenses, inadequate lens tolerance and frequent lens displacement.

Traditionally, optical Penetrating Keratoplasty (PK) has been the surgery of choice for advanced keratoconus. Over the past decade, Deep Anterior Lamella Keratoplasty (DALK) has been increasingly favoured for advanced keratoconus. DALK is a surgical technique in which the corneal stroma is removed almost down to Descemet membrane (DM), thereby preserving healthy recipient endothelium.

Purpose:

To present the results of DALK as a treatment for advanced keratoconus in Hospital Kuala Lumpur.

Method:

Fourteen eyes with advanced keratoconus underwent DALK from 2nd August 2007 to 7th May 2014. The host cornea was trephined and dissected at a depth of approximately to DM. Donor 0.25mm oversized was sutured in place after stripping of donor tissue DM.

Previously intrastromal air injection was performed as initial step before dissecting the cornea layers. Later modified Anwar big bubble, Tan’s method was performed with dissection of anterior two thirds of stroma followed by air injection using 27 gauge needle and blunt DALK cannula to form a big bubble which detaches the central DM from deep stroma. A small incision was made in the anterior wall of the big air bubble and a fine blunt spatula was used for dissecting the stroma from DM.

Figure 1: Dissection of anterior two thirds of stroma

Figure 2 & 3: Big bubble technique separating the posterior stroma from Descemet layer

Figure 3: Post DALKFigure 4: Separation of posterior stroma from DM

Results

Median age was 24.5 years old (range 20-39) , involving 9 male and 5 female.

Incidence of cornea perforation intraoperatively: NIL. One patient had double anterior chamber formation day-1 post operatively, managed successfully with intracameral 14% C3F8.

Post DALK, all eyes achieved better visual acuity; Median preop BCVA was 2.0(range 1-2), Median postop BCVA 0.349( range 0.176-0.544) p <0.05. There was improvement of the keratometry; Median preop sim K 65.7 (range 61.6-83.0), Median postop sim K 45.1 (range 36.7-65.0) p<0.05. No graft rejection noted.

Eight patients were steroid responders, one of them underwent trabeculectomy; while the remaing 7 patients had controlled intraocular pressure with antiglaucoma medications.

Discussion:

In the comparative study of DALK versus PK in keratoconus, Watson et al, reported similar visual and refractive outcomes in both DALK and PK. The sutures in DALK patients were also removed earlier and the wounds stabilized sooner in their series. This finding was also noted by Funnell et al. A quicker visual rehabilitation in patients undergoing DALK compared with PK has also been noted . The avoidance of endothelial rejection suggests that DALK is a safe and effective alternative to PK.

DALK is a safe procedure with its non penentrating nature, and less intraoperative complications. One of our patient had Descemet membrane detachement with formation of double anterior chamber, but the problem resolved after intracameral C3F8 gas injection. There have been some concerns over the risk of interface opacity with DALK. However, this did not occur in any of our patients. The complete removal of donor endothelium and Descemet’s membrane is important as inflammatory reactions and potential scarring is minimised.

Post operatively, contact lens fitting and tolerance will be more stable. There is less graft rejection rate in DALK. In our study no graft rejection reported.

Timely suture removal is important to prevent cornea vascularization and further risk of graft rejection.

Our experience showed that steroid induced glaucoma is a potential complication of DALK where patient needs to be monitored closely for optimization control of intraocular pressure to prevent graft rejection.

Conclusion

 DALK is a safe procedure and steroid induced glaucoma is a potential outcome of post DALK where patients need to be monitored closely.

References:

1. Watson SL, Ramsay A, Dart JK, Bunce C, Craig E. Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus. Ophthalmology. 2004;111:1676–1682.

2. Nima Pakrou, Shirley Fung and Dinesh Selva, Deep Lamellar Keratoplasty in the Treatment of Keratoconus, Ophthalmologica 2006;220:164–169

3. CL Funnell, J Ball and BA Noble, Comparative cohort study of the outcomes of deep lamellar keratoplasty and penetrating keratoplasty for keratoconus, Eye 2006; 20:527–532

4. Soliman A. Al-Kharashi, MD, Deep anterior lamellar Keratoplasty, Saudi Journal of Ophthalmology 2009; 23: 203– 209

5. Price F.W., Jr. Air lamellar Keratoplasty. Refract. Corneal Surg.1989;5:240–243. 

6. Luengo-Gimeno F, Tan DT, Mehta JS. Evolution of Deep Anterior Lamellar Keratoplasty(DALK). The Ocular Surface 2011;9(2):98-110