Bio-Informatic Model of Tyrosine Kinases Inhibitors in Trabecular Meshwork Cells

The behavior of potassium ion (K+) establishes the repolarization and hyperpolarization states in the cell membrane of trabecular meshwork cells. One of the main proteins that controls this ion is calcium-dependent potassium maxi-channels BKca, their malfunction evoked by tyrosine kinases, destabilize the control of aqueous humor flow and the increase of intraocular pressure, responsible of glaucoma. In the present work, the ionic behavior of ion K+ of trabecular cells is detailed, when genistein and tyrphostin-51 are applied in culture cells. The flow behavior is described by means of mathematical expressions based on exponential functions and equations of line. Genistein and tyrphostin-51 drugs are compared in their efficiency of inhibiting tyrosine kinases from the mathematical functions provided by the proposed method. The present study describes the ion behavior regarding K+ potassium which is controlled by maxi-channels BKca that come from trabecular meshwork when genistein and tyrphostin-51 are applied in culture cells. The behavior of this flow is described by mathematical expressions. Thus, inhibitor drugs effect and characteristic time behavior are compared using their mathematical function.

Computational Study on the Biomechanics of Pupil Block Phenomenon

Pupil blocking force (PBF) can indicate the potential risk of pupil block (PB), which is considered as a main pathogenic factor of primary angle-closure glaucoma (PACG). However, the effect of PB on the PBF under different pupil diameters and iris-lens channel (ILC) distance was unknown. Besides, a simple and practical method to assess PBF has not been reported yet. In this study, 21 finite element models of eyes with various pupil diameters (2.4 mm–2.6 mm) and ILC (2 μm–20 μm) were constructed and were conducted to simulate aqueous humor flow by fluid-solid coupling numerical simulation. PBF in each model was calculated based on the numerical simulation results and was fitted using response surface methodology. The results demonstrated that ILC distance had a more significant effect than pupil diameter on PBF. With the decrease of ILC distance, the PBF increased exponentially. When the reduced distance was lower than 5 μm, the PBF exploded quickly, resulting in a high risk of iris bomb. The PBF also varied with pupil diameter, especially under the condition of narrow ILC. Both ILC distance and pupil diameter could explain more than 97% variation in PBF, and a second-order empirical model has been developed to be a good predictor of PBF. Based on the linear relationship between anterior chamber deformation and PBF, a threshold value of PBF was given to guide clinical decisions. This study could be used to investigate PACG pathological correlation and its pathogenesis, so as to provide a reference value for clinical diagnosis of PACG.

Influence of Scleral Lens on Intraocular Pressure

Purpose Since Scleral Lenses (SL) rest entirely on the sclera and may affect underlying anatomical structures that may influence aqueous humor flow, it is important to determine the effect of SL wear on intra-ocular pressure (IOP). Methods Nine subjects with normal corneas were recruited for an Institutional Review Board-approved study. Best fit SL from a 15.8 mm diameter 0.4mm thick diagnostic-lens set was fitted on a randomly selected eye, with a silicone-hydrogel soft lens (soft lens) on the other eye. Three IOP measurements were taken with rebound iCare tonometer prior to lens application (baseline data measured at about 9:30AM), and immediately after lens removal (final data measured at about 5:30PM). Baseline and final lens vault was determined with anterior segment Zeiss optical coherence tomography (OCT). Mean baseline and final IOP for each eye was analyzed with a Student-t-test, 2-way repeated ANOVA, and the Bland-Altman plot. RESULTS IOP was elevated with SL wear for all subjects. Soft lens eyes showed a slight elevation for some but decreased in others. Mean IOP change was 5.81 ± 1.62 mm Hg for SL and -0.62 ± 0.88 mm Hg for soft lens eyes. When mean IOP in SL eyes was compared to soft lens eyes, unpaired t-test showed a significant difference (p <0.05) between the means. Bland-Altman bias was 6.43 (SD of bias 3.139). Repeated ANOVA also showed a significant difference between baseline and final IOP. CONCLUSIONS The results indicate that SL wear can elevate IOP. Eye care practitioners (ECP) must consider this possible outcome in treating patients wearing SL. Additional studies are needed to determine the clinical implications of SL wear on IOP.

Numerical Simulation of Multi-Field Coupling in Aqueous Humor Under the Condition of Dynamic Pressure

In order to investigate the aqueous humor flow based on the coupling effects of fluid–solid–heat under different ocular pressure, four models of rabbit eye were constructed and multi-field coupling vs. fluid–solid interaction was compared in these models. ADINA software was applied to mimic the aqueous humor flow. The contour of temperature demonstrates multiple peaks with larger value near the pupil. The flow pattern is influenced mainly by the variation of ocular pressure. It is necessary to perform multi-field coupling simulation based on dynamic pressure measurement when studying the aqueous humor flow in eyes.