A novel in vivo corneal trans-epithelial electrical resistance measurement device

Abstract

Purpose: To develop a device that is capable of easily measuring corneal transepithelial electrical resistance (TER) and changes in the corneal barrier function. Methods:We had previously developed an in vivo method for measuring corneal TER using intraocular electrode. This method can be used to precisely measure the decline of the corneal barrier function after instillation of benzalkonium chloride (BAC). In order to lessen the invasiveness of that procedure, we further refined the method for measuring the corneal TER by developing electrodes that could be placed on the cornea and in the conjunctival sac instead of inserting them into the anterior chamber. TER was then calculated by subtracting the electrical resistance, which lacked the corneal epithelial input, from the whole electrical resistance that was measured between the electrodes. Slit lamp examination and scanning electron microscopy (SEM) were used to determine safety of the new device. Corneal TER changes after exposure to 0.02% BAC were determined using the new device as well as SEM and transmission electron microscopy (TEM).Results: Slit lamp examination before and after exposure of rabbits' corneas to the sensor confirmed safety of the device. SEM examination revealed no difference of the corneal epithelium which exposed to the new device with normal corneas. SEM and 3 TEM pictures revealed damaged microvilli and tight junctions after instillation of 0.02% BAC. TER change after treatment with 0.02%BAC was similar to those determined by the established anterior chamber method. Conclusion:We succeeded to develop a less invasive device for corneal TER measurement in vivo in animals. This new device may be applicable in the future for clinical use in humans.

New Human Organotypic Corneal Tissue Model for Ophthalmic Drug Delivery Studies

“…BAC is known to increase tissue permeability and drug bioavailability by affecting tight junction integrity but it can affect tissue viability. 44,46 We confirmed that a significant part of the topical drug formulation's effect on tissue barrier integrity and viability was due to BAC (Table 6). However, since the drug formulation's effects were more pronounced than those observed after treatment with 0.02% BAC in KRB, other components of the commercial vehicle, as well as the drug itself, may contribute to or exacerbate the detrimental effect on tissue viability observed for BAC.…”

“…4). 42,[44][45][46] Light Microscopy and Hematoxylin and Eosin Staining 3D corneal tissues were harvested on day 10, rinsed in PBS, fixed in 10% neutral buffered formalin for 1 hour, dehydrated in a graded series of ethanol, and embedded in paraffin. Fivemicrometer-thick hematoxylin and eosin (H&E)-stained cross sections were prepared using standard histologic techniques 47 and examined with a light microscope (Olympus BX41; Center Valley, PA, USA) or processed using an Olympus VS120 slide scanner at 310 objective with a 30.5 camera adjustment magnification.…”

Less Invasive Corneal Transepithelial Electrical Resistance Measurement Method

“…This design more accurately reflects the clinical instillation of 11 ophthalmic drugs and provides relevant data about the acute corneal toxicity of some eye drops. [23][24][25][26] Although that previously described corneal TER measurement system in vivo was informative and reliable, it was still invasive and could not be used clinically for human studies because of intraocular electrodes. So, we developed this new less invasive corneal TER measurement method in which one electrode is placed on the surface fluid of the cornea and the other one in the conjunctival fornix.…”

“…23 In our previous studies, after developing a new in vivo method of measuring the corneal TER of rabbit corneas, we demonstrated that 0.02% BAC concentration immediately caused acute corneal barrier dysfunction. [23][24][25][26] In this study, we checked the reliability and the efficacy of this new less invasive corneal TER measurement method by measuring the corneal TER changes after application of 0.02% BAC in both rabbits and humans. The results of this new less invasive method agreed with those of the formerly established anterior chamber method used in rabbit experiments.…”

“…In order to overcome this problem, we recently developed a less invasive corneal TER measurement method. 24 In previous studies, after developing a new in vivo method of measuring the TER of rabbit corneas, we demonstrated that benzalkonium chloride (BAC) concentrations between 0.005% and 0.02% immediately caused acute corneal barrier dysfunction. [23][24][25] The purpose of 6 this study was to evaluate acute corneal permeability changes after instillation of BAC using a new less invasive in vivo TER measurement method in animals and humans.…”