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


CONCLUSIONS
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.
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan. Electronic address: uematsu1124@outlook.jp.
Masafumi
M
Uematsu
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan; Department of Ophthalmology, EL-Minia University Hospital, EL-Minia, Egypt.
Yasser Helmy
YH
Mohamed
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan.
Naoko
N
Onizuka
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan.
Ryotaro
R
Ueki
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan.
Daisuke
D
Inoue
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan.
Azusa
A
Fujikawa
Department of Ophthalmology and Visual Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, Nagasaki 852-8501, Japan.
Takashi
T
Kitaoka
D000818:Animals; D017097:Electric Impedance; D004566:Electrodes; D055724:Electrophysiological Phenomena; D019573:Epithelium, Corneal / Q000502:physiology* / Q000648:ultrastructure*; D004867:Equipment Design; D008297:Male; D008855:Microscopy, Electron, Scanning; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D010992:Plethysmography, Impedance / Q000295:instrumentation* / Q000379:methods*; D011817:Rabbits; D066167:Slit Lamp
D009883:Ophthalmic Solutions
Barrier function; Corneal epithelium; Toxicity