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August 2003
IN THIS ISSUE

Verteporfin’s efficacy in AMD comes into focus

Symposium to explore hyperopia treatment options
Epikeratophakia for keratoconus gets a second look
AMD UPDATE
Cancer trials give anti-angiogenesis a boost
RhuFab V2 trials show positive results in AMD
PDT trials aim to refine AMD treatment indications
Studies shed light on lutein’s importance to vision
Watchful eye and good use of preventive strategies needed to limit risk of phaco burn
Prolate lens design improves contrast sensitvity
German ophthalmologists prefer acrylic IOLs despite wider range of PMMA implants available
Square-edged IOL tackles PCO problems
New IOL injector yields optimum implantation with reduced learning curve
New anterior chamber phakic IOL shows good longterm safety and predictability in high myopia
Topographically guided LASIK proves first line treatment for decentred ablations
Customised ablation research produces
some answers but raises even more questions
Phakic IOL may help in refractory amblyopia
Customised approach useful in resolving
decentred ablations after LASIK and PRK
Screening can prevent post-op binocular disturbances
Anticonvulsant joins list of agents implicated in acute angle-closure glaucoma
New study shows surprise link between
hyperglycaemia and retinopathy of prematurity
Waiting lists put melanoma patients at risk
Tropicamide has little impact on higher order aberrations in myopes undergoing wavefront analysis
Swedish team tackle Moken mystery
FEATURES
From The Editor
Reflections on Refractive Surgery
Bio-Ophthalmology
Bio-ophthalmology
Eye On Travel
Regulatory Matters


Topographically guided LASIK proves first line treatment for decentred ablations

By Roibeard O’hÉineacháin in Rome

TOPOGRAPHICALLY guided LASIK re-treatment is currently the best remedy for patients with visual symptoms after a misaligned primary LASIK procedure, according to Ioannis Pallikaris MD.

Ioannis Pallikaris

The primary aim of re-treatment in patients with severely decentred ablations is to improve vision by providing a more centred and regular corneal surface. Topographically guided ablation using the TOSCA system may be the best available option in such cases, while wavefront guided ablations may be useful afterwards for reducing higher order aberrations, Dr Pallikaris told the 7th ESCRS Winter Refractive Surgery Meeting.

In a study involving 11 eyes of nine patients with a range of visual complaints associated with decentred LASIK ablations, topographically guided LASIK re-treatment using the TOSCA work station eliminated the symptoms and improved uncorrected visual acuity in all cases. There were no surgical or postoperative complications, he reported.

The patients’ symptoms included glare, halos, ghost images and binocular diplopia. After a year’s follow-up, not only had the symptoms disappeared but also the sharpness of their UCVA improved two-fold from a mean of 20/50 to 20/25.

In addition, the postoperative BCVA was also improved and nine eyes gained one line, one eye gained four and another gained five lines.
Furthermore, although the aim of the re-treatment was only to re-centre the ablation with regard to sphere and cylinder, the root mean square of their wavefront error improved from a mean of 0.6 to a mean of 0.37, Dr Pallikaris said.
"This is still high, we consider a good RMS to be less than 0.2, but it’s much better than before."

To perform the customised ablations, Dr Pallikaris first uses the Tomey TMS-3 Auto-topographer (Tomey Corp, US) to assess the nature of the corneal decentration and irregularity.
Then, using special software, he determines the ablation profile necessary to achieve the desired corneal shape and performs the ablation with a MEL 70 (Zeiss-Meditec AG, Germany) flying spot laser.

"The TOSCA system calibrates the customisation of the ablation and allows you to fine tune the depth of the ablation. This can be helpful because when you have a cornea in which you have very high differences on the elevation map you might induce a hyperopic shift and with this system we can take that into account."

Dr Pallikaris noted that the patients had no significant changes in their mean manifest sphere and cylinder. This is an important finding, especially for the case of emmetropic patients, because it allows the correction eccentric ablations without the risk of overcorrection, he pointed out.

"These patients were really suffering so I think this is a very nice approach at the moment to restore the vision. It is not the optimal solution but it is the best we have for treating these extreme cases. My belief is that we could treat these patients again with a wavefront-guided system to correct high order aberrations," Dr Pallikaris said.

Ioannis Pallikaris MD
Heraklion University Hospital, Crete, Greece
pallikar@med.uoc.gr

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