Marcelina Sobczak

Indiana University Bloomington | IUB · School of Optometry

A novel model of human corneal birefringence is presented. The cornea is treated as a homogeneous biaxial linear birefringent medium in which the values of the binormal axes angle and organization of the main refractive indices vary continuously from the apex to the limbus. In its central part, the angle between binormal axes is 35°, and para centr...

We used a partial Mueller matrix polarimeter to measure the corneal anisotropic properties at three pupil sizes (dilated, natural, and constricted). The geometrical parameters of first order isochromes were described by quadrilaterals. These parameters are statistically significantly different between the three pupil sizes. The pupillary size chang...

The trabecular meshwork (TM), located within the iridocorneal angle, is a target for many glaucoma treatments aimed at controlling intraocular pressure. However, structural variations between individuals are poorly understood. We propose a newly designed gonioscopic lens optimized for high-resolution imaging to image fine structures of the human TM...

Mueller type polarimeter was used for in vivo measurements of the anisotropic parameters (retardation and azimuth angle) of corneas. To determine birefringence, corneal thickness was measured with a Scheimpflug camera (Corvist ST). The retardation distributions in the nasal-temporal cross-section in both children (N=7) and adults (N=38) groups occu...

Objectives: The main goal of this research was to determine the differences between the values of intraocular pressure (IOP) in the supine and sitting positions, and to assess the effect of age and cardiovascular parameters. Methods: Seventy-two healthy adults were enrolled and classified into age groups: 20-30 years (group A), 31-40 years (grou...

Purpose: To undertake a comparative analysis of the corneal shape, thickness and isochromatics in the eyes of children and adults in order to determine the extent of similarities and differences between the cohorts. Methods: The study involved 24 children (aged 8 years) and 37 young White adults (aged between 22-24 years) with no apparent or kno...

This work presents the results of in vivo measurements of human corneal birefringence properties using the one-way reflective polariscope, in which the same module is used to generate and analyze the light polarization state. Data analysis was performed with the use of Mueller polarimetry techniques. The distribution of the azimuth angle and the ph...

This work presents a description of a polarimetric system for measuring the properties of birefringent media. In our reflection system the applied Stokes polarimeter acts both as a generator of the light’s selected polarization states as well as a light analyzer leaving the examined medium. The method is based on six intensity distribution measurem...

The significance of ocular mechanics to optics of the eye has important implication for understanding the dynamics of the eye that needs to maintain ocular image quality . Eye dynamics is controlled by intraocular pressure (IOP) fluctuations associated with the ocular pulse,daily rhythm and pathological high levels of IOP (glaucoma). These cause th...

The literature mentions several invasive methods to measure the degree of the compensatory torsional eye movement during a head-tilt. Nevertheless, none of them have yielded universally clinical tests. This study focuses on an optical system (with a circular polarizer) for noninvasive acquisition of corneal birefringence patterns (isochromes). The...

The purpose of this study was to evaluate the clinical utility of the output parameters of the ocular response analyzer (ORA) and those calculated from the raw ORA in subjects with healthy eyes and those with suspected glaucoma, and in patients with two types of glaucoma. The raw ORA data were analyzed using a custom software that included the Gaus...