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Session Title: New evaluation tools in refractive surgery
Session Date/Time: Sunday 06/10/2013 | 08:00-09:30
Paper Time: 08:45
Venue: Forum (Ground Floor)
First Author: : N.Waked LEBANON
Co Author(s): : S. Abou Nakad E. Jabbour J. Antoun A. Fadlallah G. Ojeimi
To determine the repartition of the corneal asphericity (Q) between positive asphericity (oblate cornea) and negative asphericity (prolate cornea), and to evaluate the possible associations between the corneal asphericity and age, sex and central corneal thickness.
Refractive surgery center in Lebanon
A retrospective, analytical study was performed on 5019 subjects examined over a period of 50 months, with the high resolution Pentacam Corneal Topography System (WaveLight Allegro Oculyzer), excluding those who have suspect or confirmed keratoconus, or those who have had a prior refractive surgery. We evaluated different parameters including anterior corneal asphericity, central and thinnest corneal thickness, age and sex
The study comprised 10 038 eyes of 5 019 patients (2503 men, 2516 women; age 4 to 72 years).The mean Q of the anterior corneal surface was 0.31 ± 0.12. 98.9% of the corneas were prolate and 1.1% were oblate. A statistically significant correlation was found between corneal asphericity and central corneal thickness (Pearson correlation = 0.03, p=0.02), such as when central corneal thickness decreases, the cornea is less prolate. However, no significant correlation was found between corneal asphericity and each of sex and age (p=0.60 and 0.41 respectively).
Corneas in our population were oblate in 110 eyes and presented high variability in Q value ranging between -0.90 and +0.42. Our results highlight the importance of the evaluation of anterior corneal asphericity Q prior to any refractive surgery, especially when performing the custom Q technique for the correction of presbyopia, where the target Q value should differ between oblate and prolate corneas.
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