Advances for Characterizing and Understanding the Irregular Cornea Renato Ambrósio Jr., MD, PhD

Financial Disclosure Allergan: B Alcon: B Moria: B Oculus: A, B Reichert: B

Evolution in Corneal Imaging KERATOMETRY (Central Corneal Power) CORNEAL TOPOGRAPHY (Corneal Surface Shape; Regularity)

Corneal Topography: Evolution from Keratometry Anterior corneal evaluation: anterior surface has convex mirror properties Reflection of virtual image whose size is determined by the radius of curvature True elevation is NOT measured, but CALCULATED Classic Keratometry (Kt): two orthogonal axes based on Helmholtz's assurances that the central cornea is a spherocylindrical surface Keratoscopes: Qualitative evaluation Computerized videokeratoscopy or Corneal Topography (S. Klyce, PhD - 1980’s)

Corneal Topography for Screening Refractive Candidates 1% of candidates were diagnosed with corneal ectasia and advised not to have the surgery These cases can have normal general eye exam and 20/20 or better BSCVA Less than ½ of these cases have any sign of ectasia at slit lamp examination

Oculus Topometric Indices (8mm surface Curvature)

Oculus Topometric Indices (8mm surface Curvature) Clinical Study: 226 Normals X 88 Keratoconus KK Indices: 7% False Negatives: 93% Sensitivity KK Indices: 13% False Positives: 87% Specificity Clinical Study: 226 Normals X 88 Keratoconus Average Q at 30º: Cut off: -0.33 Average Q at 30º : 79% Specificity and Specificity Superior Q at 30º: Cut off: -0.56 Superior Q at 30º: 88.3% Specificity and 92% Specificity

Corneal Topography Unquestionable improvement in Sensitivity to detect Ectasia Problems related to “false keratoconus” due to irregular corneal surface and not ectasia BUT it is NOT the most sensitive test to detect “earlier” or more sub-clinical cases

Asymmetric Keratoconus Placido (Axial): Absolute Scale

Pachymetry: Clinical Relevance Ultrasound (20 or 50 MHz) CCT (Central Corneal Thickness): Gaussian Distribution in normal population Central Thickness helps diagnosing ectatic disease (thinning) Mann-Whitney U Test P<0.0001 Cut off: 513µm Sens: 85% Spec: 87% AUROC:0.925

Evolution in Corneal Imaging KERATOMETRY (Central Corneal Power) CORNEAL TOPOGRAPHY (Corneal Shape; Regularity) CORNEAL TOMOGRAPHY 3D Architecture (Pachymetry)

Pachymetry Map: CCT and TP Indentification of the TRUE Thinnest Pont and its Location; Pachymetric Distribution

Thinnest Point performs statistically better than Central (apex)Thickness (N=226; KC=88) Cut off: 503µm Sens: 88.6% Spec: 90% AUROC: 0.945 Cut off: 513µm Sens: 85% Spec: 87% AUROC: 0.925

Pentacam: Corneal Thickness Profile: CTSP & PTI average of the thickness in the points within maginary circles centered on the Thinnest Point with increasing diameters

Ambrósio’s Relational Thinnest (ART)   Cut-off Sensitivity Specificity ART-Max 338.7 0.989 0.969 ART-Ave 426.4 0.943 0.978 TP 502 0.875 0.912 RPI Mid 1.15 0.932 RPI Max 1.51 0.947

Cut-Off for Ectasia Susceptibility ART-Avg = 485 μm ART-Max = 400 μm Based on cases with very asymmetric keratoconus Cases who developed ectasia after LASIK with no risk factors Cases who progressed naturally to keratoconus

Elevation Tomography: Concept of Enhanced BFS (Belin) Standard reference sphere- BFS New reference shape- (enhanced BFS)- best fits to the peripheral corneal area excluding the central area with 4mm in diameter centered on the thinnest point Michael W. Belin, MD Standard-BFS New-BFS pronounces the cone

Enhanced Elevation (Belin) will not change much in normal

Enhanced Elevation (Belin) will highlight ectasia

Corneal Characterization ARCHITECTURE or GEOMETRICAL CHARACTERIZATION (3D - TOMOGRAPHY) BIOLOGICAL PROPERTIES OF CORNEAL TISSUE Cindy Roberts, Ph.D. Corneal Wound Healing Corneal Physical Properties (Biomechanics)

Reichert ORA: First Clinical Instrument for Assessing Corneal Biomechanics

ORA Parameters CH: P1-P2 CRF: P1- (k* P2) IOPg: (P1 + P2)/2 IOPcc: K1*(P2 - 0.43*P1) + K2

What is true about Corneal Hysteresis? Reduced in Keratoconus and in Fuchs compared to normal (Luce, JCRS 2005) Reduced after LASIK and Surface Ablation (Luce, JCRS 2005; Pepose, AJO 2006) Primary open-angle glaucoma patients with diabetes have significantly higher CH values than those without diabetes (Castro, J Glaucoma 2009) Negative Correlation with Age (Kotecha, et al., IOVS 2006) No Change after Collagen Crosslinking (Goldich , Cornea 2009)

Need to Go Beyond Hysteresis Biomechanical characteristics of the ectatic cornea. Kerautret J, Colin J, Touboul D, Roberts C. J Cataract Refract Surg. 2008 Mar;34(3):510-3.

2 Clinical Examples (different patients) Normal Thin CCT: 503 µm; TP: 499 µm; RPI-Mid:0.8; RPI-Max:1.14 ART-Mid:624 µm ART-Max: 438 µm Keratoconus CCT: 545 µm; TP: 536 µm RPI-Mid:1.66; RPI-Max:2.19 ART-Mid:322 µm ART-Max: 244 µm

Normal Thin Cornea CCT: 503µm Keratoconus: CCT: 545 µm

Conclusions Enhanced Screening increases both sensitivity and specificity Current approach is based on Pentacam Tomography and ORA Biomechanics Topogrphy (Placido) is still relevant! Epithelial and stromal profile (Reinstein, VHF US and FD-OCT) Other indices will come… New biomechanical tests and models

Wavefront-Guided Ablation for Improving Vision after Previous Refractive Surgery Mounir Khalifa, MD, PhD Prof of Ophthalmology, Tanta University Horus Vision Correction Center, Alexandria Clear Vision Center, Cairo Tanta Laser Center, Tanta Egypt I have the following financial interests or relationships to disclose: WaveLight AG - C

Diagnostic tools Slit lamp biomicroscopy Refractometry Topography:* Anterior surface only. *Anterior and posterior surfaces ( Orbscan) Aberrometers Pentacam: Anterior and posterior surfaces (Scheimpflug Imaging System)

2) Irregular astigmatism 3) Increased ocular aberrations. Many patients, who received LVC, RK, or PKP complain from lost lines of BCVA, haloes, glare, star bursting, and reduced contrast sensitivity. Possible Problems in Management: 1) Difficult refraction 2) Irregular astigmatism 3) Increased ocular aberrations. 4) LASIK flap may give way at the RK scars 5) PRK is likely to result in corneal haze

Recommended Plan of Management 1) Surgical approache: PRK with MMC or LASIK 2) Ablation pattern: a) Wavefront – guided : +ve Reliable WF map b) Conventional ( Optimized/ F-CAT to improve spherical aberration) -ve reliable WF map & reliable MR &regular cornea c) Topography – guided: -ve reliable WF map & reliable MR & irregular cornea; one stage -ve reliable WF map & -ve reliable MR & irregular cornea; 2 stages

LASIK Advantages Disadvantages Fast visual rehabilitation RK scars may give way during flap cutting or elevation Intersection of cuts may induce new surface irregularities which leads to refractive errors and HOA’s.

LASIK vs PRK in RK Cases A retrospective comparative study was done to evaluate the efficiency of wavefront guided ablation in correcting ocular aberrations in RK cases. All the included eyes of 2 groups had reliable WF mapping using Wave Scan, and WF guided ablation using Visx Star S4. Gp A included LASIK using Moria M2 for 130 microns flap making, and Gp B included PRK with MMC cases ( 0.02% for 20-40 sec.). Mean follow up time : 3.5 months(1-8 ).

Demographic Data Group A ( LASIK Gp) 21 Eyes (14 patients: 9 females, 5 male) Previous RK ( 8 incisions or less): 13 ys (10 ys – 19 ys) Age: 41.5 ys (34 - 54ys) Mean of manifest sphere -3.73D(±3.57) and cylinder -1.69 D (±2.1) Group B ( PRK Gp) 18 Eyes (11 patients: 7 females, 4 males) Previous RK ( 8 incisons or more): 7 ys (6 ys – 9 ys) Age: 32.5 ys (25 – 36 ys) Mean of manifest sphere -2.92D (±2.87) and cylinder -1.9 D (±2.4)

Efficacy and Safety Indices * No significant difference between both groups in efficacy. *Significant difference ( p<0.05) in favour of LASIK in safety, may be due to 12% haze ( 2 eyes) with PRK.

Mean HOA RMS TotalHOA Coma Trefoil Sph. Aber. Significant improvement of Total HOA’S, coma, trefoil, and spherical aberration in both groups. Spherical aberration showed shift to negative side ( prolating the oblate cornea). Trefoil reduction was significant with PRK compared to LASIK (P<0.01)

Pre and postoperative HOA’s after wavefront-guided treatment of RK case.

Wavefront-Guided Ablation to Correct Ocular Aberrations After LASIK,RK,or PKP Prof.Dr. MOUNIR KHALIFA Tanta University HORUS VISION CORRECTION CENTER ALEXANDRIA,EGYPT

This prospective study was done to evaluate the efficiency of wavefront guided LASIK in correcting ocular aberrations in LVC, RK, and PKP cases.

Preoperative Mean Refraction Group A Sph. Cyl. Manifest -1.71 D(±0.35) -1.45 D(±0.71) Cycloplegic -1.37 D (±0.21) -1.39 D (±0.63) Wave Front -1.55 D (±0.42) -1.08D (±0.83)

Preoperative Mean Refraction Group B Sph. Cyl. Manifest -1.73D(±2.57) -0.69 D (±2.1) Cycloplegic -1.41D (±1.89) -0.62D (±1.96) Wave Front -1.51D (±1.87) -0.53D (±1.77)

Preoperative Refraction Group C Sph. Cyl. Manifest +2.25 D -3.50 D X 15 Cycloplegic +2.50 D -3.50 D X 12 Wave Front +2.05D -3.46 D X 19

All the eyes of the 3 groups received WF mapping using Wave Scan, and WF guided LASIK using Visx Star S4. In gp.A; 8 eyes with cutting a new flap (previous LASIK >2 years), and 44 eyes with flap left. Mean follow up time after WF: 3.5 months(1-8 ).

Group A : PSF testing in LASIK patients before and after wavefront

Group B : PSF testing in RK patients before and after wavefront

Group C : PSF testing in PKP patient before and after wavefront Note : The Corneal Scar is at the medperiphery of the ablation bed

Note : The Corneal Scar is at the medperiphery Group C : Acuity difference map in PKP patient before and after wavefront Note : The Corneal Scar is at the medperiphery of the ablation bed Note the corrected Coma

Topography- Guided Ablation

-ve WF& reliable MR & irregular cornea ( 0ne stage) ( Visx Custom Cap) 37 Ys. Lady RK on 1997 Pre-Custom Cap: MR -1.00 -2.75 X 20 UCVA: 20/80 BCVA: 20/40 Post-Custom Cap: MR -0.5 -0.75X 30 UCVA 20/30 BCVA 20/20

Topography-guided ablation (Visx Custom Cap) Pre-op Post-op

Allegro topolyzero T-CAT Allegro oculyzero Oculink Allegretto Eye-Q

Conclusions Wavefront guided ablation proved to be a useful tool to correct the unsatisfied previous corneal refractive surgery patients. Significant correction of the disturbing HOA’s can result in a significant improvement of visual performance and patient satisfaction.

Conclusions Previously LASIKed patients rendered the most satisfying results using this modality. Previous RK and PKP patients were very satisfied, in spite of the fact that corneal scars still limiting the ablation depth and the end visual performance.

Recommendation for managing previously operated cornea with refractive errors Regular cornea + clear pupillary area + BSCVA 6/6 → reliable wavefront map → Wavefront-guided PRK + MMC or LASIK (if incisions <=6) Regular cornea + BSCVA < 6/6 + unreliable wavefront map + a reliable MR→ Optimized PRK + MMC or LASIK Irregular cornea + reliable refraction → Topography-guided ablation (one stage) Irregular cornea + -ve reliable MR → Topography-guided ablation ( 2 stages)

Grossly irregular cornea + unreliable topography map → no refractive surgery (PKP may be the only solution)