Ig Pallikaris

Comparative evaluation of photorefractive keratectomy with the use of an excimer laser and a solid state laser system

Purpose To compare refractive results of photorefractive keratectomy (PRK) with the Solid State laser and Excimer laser.

Accommodative IOL' s and Pseudo Accommodation

Purpose To analyze the existing lenses designs, properties as well as the new intraocular lens technology in the field of accommodative IOLs.Moreover, to distinguish the difference between accommodation and pseudoaccommodation.

On the impact of multifocal IOL decentration and tilt on retinal image quality

Purpose The design of advanced (such as multifocal) intraocular lenses (IOLs) is based on the exact alignment of the optical element with the center of the pupil and its optical axis with the line of sight of the eye. It is the purpose of this study to evaluate the impact of multifocal IOL decentration and tilt on retinal image quality.

Intracorneal lenses for the treatment of presbyopia using femtosecond laser: visual outcomes and safety

Purpose To investigate the visual outcomes and safety of Intracorneal lenses (Flexivue Micro‐Lens, Presbia, CA)) for the treatment of presbyopia.

Straylight and corneal edema

Purpose It is known that corneal edema is associated to increased light scatter. It was the purpose of this study to calculate the intensity and angular distribution of scattered light in a series of corneal samples at different hydration, using a sensitive optical technique.

Intravitreal combination of triamcinolone acetonide – bevacizumab (Kenacort–Avastin) in diabetic macular edema

Purpose To evaluate the effect of intravitreal injection of Triamcinolone Acetonide – Bevacizumab (Kenacort®)-(Avastin®) in the treatment of diabetic macular edema Methods Twenty seven eyes of 17 patients with diabetic macular edema participated in this study. Each patient received an intravitreal injection of 0,1 ml triamcinolone acetonide (Kenacort®) (0,2mg)combined with bevacizumab (Avastin®) (1,25mg). Mean age was 64years and mean duration of diabetes 15,5years. The primate outcome measures were changes in best corrected visual acuity and in central macular thickness measured by OCT. The follow up period was six months from the first intravitreal therapy. Results During the follow up period 3 eyes(11%) received one, 18 eyes(67%) received two and 6 eyes(22%) received three intravitreal injections according to the monthly follow up examination. There were not observed any important complications of the intravitreal combination of Triamcinolone Acetonide – Bevacizumab either during or after the treatment. The mean visual acuity increased 0,12 (decimal) (p<0,0001) and the central macular thickness decreased 235μm (p=0,018). Conclusion Intravitreal combination of Triamcinolone Acetonide – Bevacizumab seems to be effective in improving visual acuity and macular edema in patients with diabetes.

Optical simulation of large and small angle scatterers

Purpose However corneal scattering is clinically often quantified as haze (backscattered light), the visual function is affected by the forward light scattering in the anterior ocular media. The angular light distribution of the scattered light is inherent to the interaction between the light and the scattering media. The purpose of this study is to describe an optical model of the scattering tissues in the cornea and compare its light propagation to experimental single pass scattering measurements. Methods Histologic data and confocal imaging of the cornea revealed that a significant portion of corneal scattering originates by keratocytes and scar tissue created during a wound healing process, e.g. after refractive surgery. Keratocytes were modeled as small spheres, angular scattering distribution is derived on the Mie theory. The parameters were optimized to meet the light distribution measure by a single pass experiment through excised rabbit corneas. Results Single pass scatter measurements of excised rabbit corneas revealed a narrowly forward peaked scattering distribution (FWHM 30 arcmin), corresponding to a distribution of scattering spheres with 36μm+/-15 radius and a relative refractive index of 1.0024. Scattering ratio (SR), equal to the scattering cross section, varied from 0.2 (clear) to 0.7 (scarred). The SR was correlated with the scar tissue thickness (0.79) and haze grade (0.51), Pearsons coefficient. Conclusion Despite the non-spherical geometry of keratocytes, we presented a simple model to describe the corneal scattering distribution, controlled by physically relevant parameters as observed in histologic and confocal microscopy. Optical simulations based on light propagation through random phase maps may result in more realistic scattering models.