Noncontact type tonometer
AssigneeNidek Co., Ltd.
InventorTetsuyuki Miwa
Life of this patent
Estimating the term…
Abstract
A noncontact type tonometer monitors the rate of change X(t) in pressure between a standard curve and a measured curve. If X(t) exceeds a value of 1.3, the application of air pressure is stopped to prevent an abnormal rise in pressure. If X(t) is equal to 1, then the measured curve follows the standard curve and correction is not required. If X(t) is not equal to 1, an error condition exists and an amended time t′ is calculated based on the rate of change X(t). Instead of a calculated amended time, an approximated standard curve can also be determined based on either an equation stored in a memory or by matching the measured curve with one of a plurality of standard curves stored in memory.
Claims11
A noncontact type tonometer comprising:
- compressing means for forming compressed air;
- direction means for directing the compressed air to a cornea of a patient's eye;
- deformation detection means for detecting a flat deformation state of the cornea to which the compressed air is directed by the direction means;
- memory means for storing a standard pressure curvature of the compressed air that changes according to passage of time, the standard pressure curvature being inherent in the compressing means;
- pressure detection means for detecting a pressure changing curvature in the compressed air directed by the direction means;
- and
- processing means for determining an amended pressure changing curvature based on the pressure changing curvature detected by the pressure detection means and the standard pressure curvature stored in the memory means,
- wherein the processing means calculates an intraocular pressure of the patient's eye based on the amended pressure changing curvature.
A noncontact type tonometer comprising:
- compressing means for forming compressed air;
- direction means for directing the compressed air to a cornea of a patient's eye;
- deformation detection means for detecting a flat deformation state of the cornea to which the compressed air is directed by the direction means;
- memory means for storing a standard pressure characteristic of the compressed air;
- pressure detection means for detecting a pressure change in the compressed air directed by the direction means;
- and
- processing means for performing a pressure comparison to compare the pressure change in the compressed air detected by the pressure detection means with the standard pressure characteristic stored in the memory means, and judging whether the pressure change exceeds a predetermined standard based on the result of the pressure comparison,
- wherein the processing means controls the operation of the direction means and stops the drive of the direction means when it is judged that the pressure change exceeds the predetermined standard.
A noncontact type tonometer comprising:
- compressing means for forming compressed air;
- direction means for directing the compressed air to a cornea of a patient's eye;
- deformation detection means for detecting a flat deformation state of the cornea to which the compressed air is directed by the direction means;
- memory means for storing a plurality of types of standard pressure curvatures of the compressed air that change according to passage of time;
- pressure detection means for detecting a pressure changing curvature in the compressed air directed by the direction means;
- and
- processing means for performing a pressure comparison to compare the pressure changing curvature in the compressed air detected by the pressure detection means with the standard pressure curvatures stored in the memory means and selecting one standard pressure curvature which is the most approximate to the pressure changing curvature,
- wherein the processing means calculates an intraocular pressure of the patient's eye based on the selected standard pressure curvature.
Dependencies are inferred from the claim text.