Transcript Bilateral phacoemulsification and intraocular lens (IOL

Bilateral phacoemulsification and
intraocular lens (IOL) implantation for
bilateral corneal ectasia after
photorefractive keratectomy (PRK)
Anita S.Y. Ng, Arthur C.K. Cheng, Srinivas K. Rao, Philip T.H. Lam,
Dennis S.C. LAM
Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, University Eye Center,
Hong Kong Eye Hospital, 147K, Argyle Street, Hong Kong, People’s Republic of China.
Purpose
• To report the occurrence of bilateral
corneal ectasia after PRK
• To discuss the methods of IOL power
calculation and the phacoemulsification
surgical outcomes in these eyes.
Method
• A case report of two eyes of a patient who received
PRK in both eyes in 1992.
• History:
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presented with progressive blurred vision in 2002.
BCVA: OD: 20/30 (-5.0/-1.75x75), OS: CF
Bilateal nuclear sclerosis
Corneal topography: irregular astigmatism with the
steepest zone located inferotemporally suggestive of
keratectasia, more marked on the left (figures 1a &1b).
Method
figure 1a
Method
figure 1b
Method
• Had consecutive phacoemulsification and IOL
implantations.
• OS: Gaussian optic method (contact lens refraction
was not possible due to poor visual acuity). Target
refraction = -2.0D
• OD: Contact lens method, target refraction -0.75D
Limbal relaxing incision with a 600m diamond
knife centered at 332 deg with an arc length of 90
deg was performed at the same setting.
Results
• BCVA: OD: 20/20 (-0.50/-0.75 x 70)
OS: 20/30 (-2.25/-1.25 x 115)
• Satisfactory accuracy in determining the
corneal power was achieved with both
Gaussian optics method and contact lens
methods, though both methods showed a
slight overestimation of the corneal power.
Results
• The corneal topographic examinations have
not changed during the3-year follow-up
period.
• LRI has corrected the astigmatism on the
right eye.
Results
• We hypothesized that weakening in the
peripheral cornea in our patient with
ectasia might slow down the progression
of central corneal changes.
• Longer-term follow up and larger patient
group are needed to study this further.
Conclusions
• We report the uncommon occurrence of bilateral
keratectasia after PRK in a patient.
• Both the Gaussian optics formula and contact
lens methods for IOL calculation worked well.
• We also used a LRI in one eye during surgery.
The effects of such surgical procedure on the
long-term progression of the corneal ectasia
however, remain to be seen.
References
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Rao SK, Srinivasan B, Sitalakshmi G, Padmanabhan P.
Photorefractive keratectomy versus laser in situ keratomileusis to
prevent keratectasia after corneal ablation. J Cataract Refract Surg
2004;30:2623-8.
Hamed AM, Wang L, Misra M, Koch DD. A comparative analysis of
five methods of determining corneal refractive power in eyes that have
undergone myopic laser in situ keratomileusis. Ophthalmology.
2002;109:651-658.
Hoffer KJ. Related Articles, Links Intraocular lens power calculation
for eyes after refractive keratotomy. J Refract Surg 1995;11:490-3.
Wang L, Swami A, Koch DD. Peripheral corneal relaxing incisions
after excimer laser refractive surgery. J Cataract Refract Surg
2004;30:1038-44.