ALLEGRETTO - Pacific Laser Eye Centre

Report
Topographically-guided photo-refractive
keratectomy (TG-PRK) for complications
of refractive surgery
David TC Lin, MD, FRCSC
Simon Holland, MD, FRCSC, FRCS(Eng), MRCP,
FRC Oph
Pacific Laser Eye Centre
UBC Dept of Ophthalmology
ASCRS, San Diego 2011
No financial interests
Aim
 Management of complicated laser refractive
surgery challenging
 Patients often intolerant or reluctant to use
specialty contact lenses
 Surgical options - limited as often unable to
capture wavefront analysis if severely aberrated
cornea
 Evaluate topographically guided photo-refractive
keratectomy (TG PRK) for symptomatic patients
with decentered ablations (DA) and radial
keratotomy
(RK)
Methods
 Custom neutralizing technique (TNT) for
aberrated corneas with decentered ablation
(DA) zones after laser refractive surgery and
radial keratotomy (RK)
 Allegretto Wavelight topographically-guided
(TG) laser
 Retrospective case series, 94 eyes DA and 49
eyes with irregular astigmatism following RK
 Previous LASIK or PRK
 LASIK Flap lift; PRK Trans-epithelial,
 PTK with mitomycin C
Topographical Neutralisation
Treatment
Method of compensating for induced refraction
change by surface regularization
1. Plano TG: i.e. hyperopic effect in
increasing optical zone after RK
2. Correction of astigmatism induced by
plano TG
3. Correction of sphere induced by 1 and 2
4. Manifest refraction added =
5. final treatment
Methods : TG PRK for DA ,
RK
 Patient evaluation:
- symptom score - blurred vision,
doubling , glare , haloes, starbursts
- pre and post UVA, BSCVA, refraction,
topography, change in centration relative to
pupil center, predictability, safety
TG PRK for DA
14 months LASIK
UCVA : 20/30
Pre-op: +0.75-0.50x117 20/20-
3 months post-op
UCVA : 20/20RX: +0.25
20/20
TG PRK for RK
20 years RK, LASIK
BSCVA: 20/80
Pre-op: +4.75-3.25x105
6 months post-op
UCVA: 20/60Rx: -1.00
20/40
TG PRK for RK
20 years RK, LASIK
6 months post-op
UCVA: 20/50
UCVA: 20/200
Pre-op: +1.50-1.75x150 20/25 Rx: -1.75 20/25
TG PRK for RK
20 years RK, LASIK
UCVA: 20/100
Pre-op:+3.75-1.50x172 20/25
4 months post-op
UCVA: 20/20
Rx: +0.75 20/20
Summary of Results Decentered Ablations
 UCVA >= 20/40 77% . >= 20/25 65%
 24% gained ≥1 lines, 71% no change, No loss
>2 line
 Mean centration: from pupil center improved
from 0.92mm to 0.30mm (p<0.01)
 All had improved astigmatism, 1.25D-6.75D
 All symptomatic prior to surgery , 19% still
had symptoms following, rated >3 on 4 point
scale as moderate/severe
Summary of Results: RK
 UVA >=20/40 62% >= 20/25 18%
 Lost and gain >= 2 lines – 7%
 Symptoms - improved in 72% .
Discussion
 TG laser treatment for DA more predictable ,
better UCVA and less loss of lines than
when performed for irregular astigmatism
after RK
 Tendency to overcorrect post-RK due to
hyperopic effect of TG –expect to regress
 Persisting diurnal fluctuation
 Alleviated more severe symptoms in
most patients in both groups
Conclusion: TG laser for aberrated
corneas after previous refractive
surgery
 Valuable option for highly symptomatic
patients with Decenterd Ablations and after
RK
 Refractive predictability is better with
neutralization (Custom TNT) but still needs
improvement
Palmyra,
Syria

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