Clinical outcome of DALK in Keratoconus – A one year follow up Authors: Somasheila I Murthy, MD, Smruthi rekha Priyadarshini, MD, Jagadesh Reddy, MD and Prashant Garg, MD. Affiliation: Cornea and anterior segment service, L. V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, India The authors have no financial interest in the subject matter of this poster

Methods Study purpose: To evaluate the visual outcome and complications of deep anterior lamellar keratoplasty (DALK) in keratoconus Study design: retrospective interventional case series Study location: Cornea and anterior segment service, LV Prasad eye Institute, Hyderabad, India Inclusion criteria: all cases of keratoconus that underwent DALK with a minimum follow-up of one year Pre-operative evaluation included: Visual acuity Slit lamp examination Central corneal thickness Corneal topography

Methods The data obtained included: pre and post-operative: Best corrected Snellen’s visual acuity Slit-lamp examination for assessment of graft clarity Central corneal thickness Corneal topography using Orbscan Anterior segment optical coherence tomography post-operatively in some cases Surgical technique: 2 techniques: Big-bubble technique Manual dissection in layers Combination Primary outcome measures: Visual acuity Graft clarity Secondary outcome measures: Nonprogression of keratoconus Graft failure due to edema or rejection Complications rate

Results During 2004 to 2008, 49 eyes of 48 patients underwent DALK Table 1: Age distribution During 2004 to 2008, 49 eyes of 48 patients underwent DALK Twenty-two eyes completed one year follow-up Mean age: 18.63 (range 11 to 43 years) with 77% under 20 years Fifteen were male and seven female patients Age Eyes (%) 11 – 20 yrs 17 ( 77%) 21 – 30 yrs 2 (9%) 31 – 40 yrs 2 (9 %) > 40 yrs 1(4.5%)

Results: pre and post-operative visual acuity Table 2: Pre-operative visual acuity Table 3: Post-operative visual acuity Visual acuity > 20/ 60 Eyes 6 20/60 – 20/ 200 4 20/200 – 20/400 3 <20/400 13 (60%) Visual acuity 20/20-20/40 Eyes 16 (73%) 20/40-20/60 2 20/60-20/80 < 20/80

Results Corneal thickness ranged from 427 to 591 microns Table 4: Surgical technique Big bubble 7 Manual lamellar dissection 3 Combination 12 Total 22 Corneal thickness ranged from 427 to 591 microns Donor graft size ranged from 7.5 to 10.5

Results: graft clarity and complications Table 5: Graft clarity Table 6: Complications Clear graft 16 (73%) Interface haze 2 Scarring 3 Pigments on endothelium 1 Suture related 9 Vascularisation 3 PAS 1 None 8

Summary Best-corrected visual acuity at one year was 20/40 or better in 16/22 cases (73%) 16/22 cases had clear graft, with 5/22 showing interface haze or scarring No major complications like glaucoma, graft failure or progression were noted Minor suture related complications (loose or broken sutures) were noted in 9 eyes (40%)

Discussion Penetrating keratoplasty is the accepted surgical treatment for keratoconus and has an excellent five-year graft survival rate1,2 However, it can fail due to allograft rejection and endothelial cell loss Deep anterior lamellar keratoplasty replaces anterior diseased part of the cornea while retaining the host endothelium and has the advantage of reducing the risks of graft rejection and intraocular complications

Discussion Various authors have reported their results of DALK and have shown comparable visual acuities with PK with fewer post-operative complications3, 4, 5 Our study also shows similar results Therefore, despite this technique being more demanding surgically, it is worthwhile to perform DALK for keratoconus and PK should be done only as a last resort

Conclusions Visual acuity outcomes of DALK in keratoconus are good in majority of cases In comparison to penetrating keratoplasty, there are fewer post-operative complications and majority encountered were minor DALK is perhaps the preferred choice for the surgical management of keratoconus

References: Pramnik S, Musch DC, Sutphin JE, Farjo AA. Extended long-term outcomes of penetrating keratoplasty for keratoconus. Ophthalmology 2006;113:1633-1638 Zadok D, Schwarts S, Marcovich A, et al. Penetrating keratoplasty for keratoconus: long term results. Cornea 2005;24:959-961 Watson SL, Ramsay A, Dart JKG, et al. Comparison of deep lamellar keratoplasty with penetrating keratoplasty in patients with keratoconus. Ophthalmology, 2004;111:1676-1682 Sarnicola V, Toro P, Gentile D, et al. Descemetic DALK and pre-descemetic DALK: outcomes in 236 cases of keratoconus. Cornea 2010 Jan;29(1):53-9 Han DY, Mehta JS, Por YM et al. Comparison of outcomes of lamellar keratoplasty and penetrating keratoplasty in keratoconus. Am J Ophthalmol 2009;148(5):629-31