CATz for Highly CATz for Highly Irregular Corneas after Irregular Corneas after

Keratorefractive Keratorefractive SurgerySurgeryHamed M. Anwar, MD, FRCSHamed M. Anwar, MD, FRCS

Alaa El-Danasoury, MD, FRCSAlaa El-Danasoury, MD, FRCS11

Institutional affiliation:Institutional affiliation:Magrabi Eye Hospital,Magrabi Eye Hospital,Jeddah, Saudi ArabiaJeddah, Saudi Arabia..

11 . . Dr. Alaa El-Danasoury is a consultant to Nidek Co. Ltd, Dr. Alaa El-Danasoury is a consultant to Nidek Co. Ltd, Gamagori, JapanGamagori, Japan..

IntroductiIntroductionon

Keratorefractive surgery Keratorefractive surgery such as LASIK and radial such as LASIK and radial keratotomy can reduce keratotomy can reduce visual acuity due to visual acuity due to induction of higher order induction of higher order aberrations.aberrations.

Decreased visual acuity in Decreased visual acuity in such cases is due to an such cases is due to an irregular corneal surface.irregular corneal surface.

Management modalities Management modalities include:include: Extensive postoperative Extensive postoperative

counseling,counseling, Pharmacologic interventionPharmacologic intervention Contact lens therapyContact lens therapy Topography-guided Topography-guided

retreatmentretreatment

Topography guided retreatments may be a Topography guided retreatments may be a better option compared to wavefront guided better option compared to wavefront guided treatments in such patients as:treatments in such patients as:Quality of topographic Quality of topographic images can be checkedimages can be checked

Data isn’t limited Data isn’t limited to pupillary area.to pupillary area.

Data limited to pupillary Data limited to pupillary area.area.

Questionable reliability of Questionable reliability of data in highly aberrated data in highly aberrated eyeseyes

Shack-Hartmaann Shack-Hartmaann aberrometryaberrometry

CATzCATzKey Key conceptsconcepts

•Uses scanning spot for irregular ablationUses scanning spot for irregular ablation•Uses scanning slit for sphere & CylinderUses scanning slit for sphere & Cylinder•Corneal topography guided ablationCorneal topography guided ablation

The basic treatment in CATz is the aspheric The basic treatment in CATz is the aspheric ablationablation

Oblate cornea:Oblate cornea:Conventional Conventional ablationablation

Conventional Conventional ablationablation

CATzCATz

The “red ring” The “red ring” indicating the indicating the transition zone transition zone (TZ) is more (TZ) is more peripheral and peripheral and less less pronounced in pronounced in the CATz the CATz ablationablation

Prolate Prolate cornea: cornea: Aspheric Aspheric ablationablation

Demographics and patientsDemographics and patientsnn8 eyes of 7 patients8 eyes of 7 patients

Mean ageMean age34 years 34 years (23y (23y –– 47y) 47y)

GenderGenderMales Males –– 100% 100%

VASCVASC>20/30 in all cases>20/30 in all cases

Mean SE:Mean SE:-1.23 D ± 2.03 D -1.23 D ± 2.03 D Range (-4.38 to 2.50)Range (-4.38 to 2.50)

Mean Cyl: Mean Cyl: -0.84 D ± 0.38 D (-0.84 D ± 0.38 D (Range (-1.25 to -0.25)Range (-1.25 to -0.25)

Corneal irregularitiesCorneal irregularities20-33um20-33um

Night vision complaints in all patientsNight vision complaints in all patients

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Ablation centered midway Ablation centered midway between corneal vertex between corneal vertex and pupil center (50% and pupil center (50% PDist on FinalFit)PDist on FinalFit)

No treatment of spherical or cylindrical error due No treatment of spherical or cylindrical error due to the high degree of corneal irregularityto the high degree of corneal irregularity

100%100% treatment rate treatment rate of all irregularitiesof all irregularitiesCorneal wavefront Corneal wavefront mode usedmode used

MethodsMethods•Corneal topography, wavefront data, and Corneal topography, wavefront data, and pupillometry were acquired using the OPD-Scan IIpupillometry were acquired using the OPD-Scan II•All surgeries were planned using Nidek Final Fit All surgeries were planned using Nidek Final Fit 1.13 software1.13 software•Ablation performed with Nidek EC-5000 CXIII Ablation performed with Nidek EC-5000 CXIII excimer laser excimer laser

Mean HO MTF over timeMean HO MTF over time

Results Results –– 8 eyes at 1 year 8 eyes at 1 yearPostoperatively Postoperatively 50% of all eyes saw 50% of all eyes saw 20/20 20/20

All eyes saw All eyes saw better than better than 20/3020/30

Improvement in modulation Improvement in modulation transfer frequency values transfer frequency values postoperativelypostoperatively

Cumulative BSCVA of patients Cumulative BSCVA of patients before and after CATz treatmentbefore and after CATz treatment

The higher order MTF plots the The higher order MTF plots the effect on visual performance of effect on visual performance of the higher order aberrations, not the higher order aberrations, not sphere and cylinder.sphere and cylinder.

Coma RMS over time [Coma RMS over time [m]m] Spherical aberration (Z12) over Spherical aberration (Z12) over time (time (m)m)

Results (cont)Results (cont)

0.450.45m decrease in the mean coma m decrease in the mean coma postoperativelypostoperatively

0.450.45m decrease in the mean higher m decrease in the mean higher order spherical aberration order spherical aberration postoperativelypostoperatively

MTF:Poor quality of visionA/B = 0.197H/B = 0.363

PSF:Poor qualityWF error: 1.28Strehl Ratio: 0.01

OPD HO:Coma RMS = 1.83

Topography:Small EOZ = 4 mmWell centered ablation

Case example•1 year after LASIK (2006 Flying spot laser):•Night Vision symptoms (Starbursts )•UCVA: 20/20•MR: 0.00 -0.25 x 20•BSCVA: 20/16•Pachymetry 450•Mesopic pupil 6.7 mm

Enlargement Enlargement of functional of functional optical zone optical zone from 4mm to from 4mm to 6mm6mm

Difference map shows Difference map shows the targeted area of the targeted area of localised ablationlocalised ablation

Decrease in Decrease in OPD HO coma OPD HO coma RMS from 2.07D RMS from 2.07D to 1.2Dto 1.2D

Point spread function (PSF) improvement shown by the Strehl ratio increase from 0.01 to 0.04 and WF error decrease from 1.28m to 0.6m

Modulation transfer function (MTF) shows an improvement on the higher spatial frequencies.

A/B and H/B ratios increase.

ConclusionConclusion

Customized Topography Guided Ablation using Final Fit 1.13 & the CATz profile is safe and effective in the treatment of corneas with high irregularities after keratorefractive procedure.