Comparison of Early Outcome of Topo-guided Photo-refractive Keratectomy Between Two Refractive Lasers

Purpose: Evaluation of topography-guided photorefractive keratectomy with collagen cross-linking (TG PRK/CXL) for keratoconus(KC) with two lasers

Methods:482 Keratoconus (KC) eyes – Wavelight Allegretto (WA) 144 KC eyes - Schwind Amaris (SA) Trans-epithelial TG-PRK with simultaneous CXL as per modified Dresden protocol. Treatment targeted at -1.25 post-opWA - Topographical Neutralization Technique (TNT), with minimal residual stromal depth 300 microns. Data evaluated: pre-operatively, 1, 2, 3, 6 and 12 months:- uncorrected visual acuity (UCVA), best corrected (BCVA/CDVA), manifest refraction (MR), symptom score, topography and keratometry

Results:WaveLight Allegretto (WA):182 eyes completed 12 months or more follow-up. 91 (50%) had ≥20/40 uncorrected visual acuity (UCVA). 92 (51%) had BCVA improved, 53 (29%) improved BCVA 2 lines or more, 13 (7%) lost 2 lines or more. Mean reduction of astigmatism was 1.82±1.73 diopters(D). Mean spherical equivalent reduced from -2.88±2.79D to -1.21±2.19D. Complications included delay in epithelial healing, with subsequent haze, 3 sufficient to reduce BCVA more than 2 lines, 3 undergoing PK; HSV keratitis, 1 recovering pre-operative BCVA after PTK. Glare, halos, difficulties night driving decreased 3.5 to 2.0 (n=25).

Schwind Amaris (SA):43 eyes completed 12 months or more follow-up. 49% (21/43) had ≥20/40 UCVA. 86% (37) had ≥20/40 BCVA, 44% (19) had BCVA improved ≥ 1 line, 30% (13) had improved BCVA ≥ 2 lines, 30% (13) no change, 14% (6) lost ≥2 lines. Mean astigmatism decreased from -3.08D pre-operatively to -1.56D post-operatively

Conclusion:Early results of Schwind TG-PRK with simultaneous CXL potential as effective treatment for CL intolerant KC patients. Almost half of the cases had ≥20/40 UCVA and improved BCVA at 12 mths. Customization – possible when poor image capture with other systems. Excellent tracking - Cyclotorsion control and defocus. Larger study of one year results of 182/482 eyes with sufficient data for analysis with Allegretto Wavelight TG PRK with CXL. Similar results with both systems - SA offers advantages of iris tracking, cyclotorsion control and image capture while AW has a larger data base and longer term follow up in this study.

References:1. Lin,DTC, Holland,SP, et al. Method for optimizing topography guided ablation highly aberrated eyes with the ALLEGRETTO wave excimer laser. JRS 2008;24(4):S439-S445.2. Stojanovic A, Zhang J, et al. Topograph-guided transepithelial surface ablation followed by corneal collagen crosslinking performed in a single combined procedure for the treatment of keratoconus and PMD. JRS 2009;26(2):145-152.3. Kanellopoulos AJ, Binder PS. Collagen cross-linking with sequential topography-guided PRK:a temporizing alternative for keratoconus to penetrating keratoplasty, Cornea 2007;26:891-8954. Vinciguerra P, Albe E, et al. Intraoperative and post-operative effects of corneal collagen cross-linking on progressive keratoconus. Arch Ophth 2009;127(10):1258-1265.

Representative Cases:

simon_holland@telus.net

Pacific Laser Eye Centre tel: (604)736-2625

CASE of WAPreop : -9.50-1.00x030 18 months postopBSCVA : 20/20-2 UCVA :20/25TG PRK : -7.92-1.80x030 Rx : -0.50sph 20/20

Pre-Op Pos-Op Pos - Pre

Simon P. Holland MB, FRCSC, FRCS, MRCP; David T.C. Lin MD FRCSC; Umi K. Noh MB BCh BAO, Ms(Ophth)

Pre-Op Pos-Op Pos - PrePre-Op Pos-Op

Pos - PrePre-Op Pos-Op

CASE of SAPreop 12 months postopBSCVA: 20/25-1 UCVA: 20/40MR: -7.25-2.00x090 MR: +0.50sph 20/40Tx depth: 63.63µm

14.0%

7.1%

11.6%12.1%

30.2%30.2%

14.0%

21.4%

30.2%29.1%

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

% o

f C

as

es

LOSS 2 LINESOR MORE

LOSS 1 LINE NO CHANGE GAIN 1 LINE GAIN 2 LINES ORMORE

BCVA Gain/Loss

BCVA Change of TG PRK CXL for KC at 12 Months PosOp, AW and Schwind

Schwind (N=43)

AW (N=182)