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Session Title: Presbyopia Correction
Session Date/Time: Monday 07/10/2013 | 16:30-18:15
Paper Time: 17:06
Venue: Emerald (First Floor)
First Author: : C.Ghenassia FRANCE
Co Author(s): :
Targetting a negative Q value on the Wavelight F-Cat software induces an undercorrection for hyperopic treatment and an overcorrection for myopic treatment. This shift is affected by ametropia, pre-op keratometry, pre-op asphericity and the optical treatment zone. The PresbyCor software produces an exact calculation for treatment with a negative asphericity value, based on depth ablation and defocus aberration. The nomogram takes into account all the criteria that induce a myopic or hyperopic shift.
Charles Ghenassia M.D. New Vision, Nice - France
The calculation engine is based on a database containing calculations using the data of several thousand patients, with diopters ranging from -6.00 (cylinder < 2.00) to +4.00 (cylinder < 2.00), wih increments of 0.25D and target asphericity of -0.80 for hyperopia and emmetropia and -1.00 for myopia. These calculations include a nomogram to compensate for ametropia, presbyopia, keratometry and the optical treatment zone, with respect to a reference value for ablation depth for a standard treatment. The compensation factor is not linear and is calculated based on an ideal ablation depth for ametropia or the defocus aberration induced. The PresbyCor software can be installed on a tablet or laptop. It is very simple to use : after patient data is entered, the calculation engine displays the values to be used in the F-cat software.
We have collected post-op results with a follow-up of more than 2 years on 75 patients treated with Presbylasik guided by asphericity, using the PresbyCor software on Allegretto 200 and EX500 Wavelight lasers. Results show a residual accommodation potential of 2 diopters (evaluated with OQAS) for the great majority of patients. Analysis of the internal and corneal spherical aberrations with the Itracey Combo show a reduction of corneal SA+ due to an increase in negative internal spherical aberration, and an increase in corneal asphericity, which might be proof of the reactivation of accommodation. Results in terms of visual acuity show that 73% of patients are 20/20 in DV, 18% at 16/20 and 9% at 18/20. 98% of patients are at jaeger 1 and 1,5.
The PresbyCor is simple to use and can prevent the creation of an under- or overcorrecting shift tied to the programming of negative asphericity on the Wavelight F-Cat software, by taking into account pre-op keratometry and asphericity. It can extend indication for the treatment of presbyopia using laser in myopic, hyperopic, and emmetropic patients, thanks to historical data going back several years. It also takes into account residual accommodation, which plays a much greater role than is currently assumed.
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