One Step Beyond

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One Step Beyond. Refractive Surgery Challenges and their most modern approach D. Alexopoulos MD,DO www.lasereye.gr. Some of the most challenging refractive problems. Eccentric ablation Irregular, eccentric ,small optical zone after RK Hyperopia after myopic ablation - PowerPoint PPT Presentation

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One Step Beyond

One Step BeyondRefractive Surgery Challenges and their most modern approach

D. Alexopoulos MD,DO

www.lasereye.gr

Some of the most challenging refractive problemsEccentric ablationIrregular, eccentric ,small optical zone after RKHyperopia after myopic ablationVision improvement in KCN

heir treatment has been attempted with variable success by the use of topography guided ablation, and in case of KCN with the addition of corneal cross linking (Topo Guided PRK Athens Protocol Kanellopoulos) The reasons for the variable success of such treatments have been :

The inability to control the static and dynamic torsion of the eyeThe lack of reliable and precise registration of the planed ablation on the corneaThe assumption of Pentacam of the corneal surface shape (best fit sphere maps change with fitting)The compensatory role of the corneal epithelium

We can now overcome the problems of imperfect registration of the ablation and be more precise at defining the corneal surface contour by using the Amaris (Schwind) platform in combination with Corneal Wavefront analysisThe Amaris uses a static & dynamic torsion control up to 12,5 degrees) and has a 6D eye trackerAmaris eye tracker

Few remindersRegistration of the ablation= matching the desired corneal ablation on the corneal surface ( avoid eye torsion or decentration)Corneal wavefront= Zernicke analysis of the corneal topography (higher order aberrations of the corneal surface)Accelerated corneal crosslinking= Corneal collagen crosslinking by the use of high diffusion riboflavin formulations (Vibex Rapid) and high energy UV (30mW) for shortened periods of treatment (8min pulsed light)Partial crosslinking = Crosslinking of the anterior corneal stroma as in accelerated crosslinking but less soaking time (90 sec) and less irradiation (75-90 sec at 30 mW)

Corneal wavefront Zernike analysis

Advantages of Corneal Wavefront maps

1. Show the cornea in terms of its optics2. Allow analysis of individual aberrations3. Allow simulations of vision, PSF, MTF4. Allow comparison with aberrometersAmaris static cyclotorsion correction

Diagnosis imageLaser image

Case 1: old RK with small ,decenterd OZBCDVA4/10 -4.00/-4.00 cylCorneal Wavefront of case 1

Corneal OCT of case 1

Treatment plan (ablation pattern) of Case 1Corneal Wavefront Guided Transepithelial PRK Xtra (followed by accelerated partial crosslinking ) & MMC

Post op Case 1 BCDVA 9/10 -1.50 sph

Pre/Post op difference map Case 1

Case 1 Corneal OCT post op

CCL depth 190Case 1 20 days post op

Case 2: Moderate KCN BCDVA 5/10 (cant wear GP)

Case 2: Corneal Wavefront

Case 2 : Corneal OCT

Epi 52Epi 60Case 2: Treatment plan (ablation pattern)Corneal Wavefront Guided Partial transepithelial Prk followed by full accelerated pulsed crosslinking & MMCCase 2 Post op BCDVA 10/10-

Case 2 corneal OCT post op

Case 2 1 month post op

Case 3: Hyperopia after myopic PRK(cct 460 ) treated with thin flap (100) femto lasik & CCL Xtra

Case 3 1 month post op

What was knownregularly irregular corneal surface could be treated with Topography or WF guided ablationTopography guided ablation was based on Pentacam images and WF guided on total ocular WF measurementsSuch WF guided treatments were not quantifiable ,HOA wiseThe corneal epithelium was removed as in PRK or PTKThe Athens Protocol by Dr. Kanelopoulos is based on the above plus corneal crosslinkingPost myopic PRK consecutive hyperopia was treated with Hyperopic PRK (fear of ectasia)

Whats newThe corneal wavefront guided ablation treats the optical irregularities of the aberrated cornea It combines the meaningful and substantial WF guided ablation but focused solely on the corneal surface contribution (as the topo guided ablation)This must be coupled with a precise ablation registration (with torsion control) and a fast and reliable eye trackerTransepithelial PRK makes use of the smoothing effect of the corneal epithelium Accelerated ,partial or full crosslinking, effectively strengthens the cornea after such treatmentsThe use of Femto thin flap Lasik combined with partial crosslinking (Xtra) can be safely used in treating consecutive hyperopia after myopic PRK What I would like for Christmas!

New topographer!Cassini???