Computer refractometer is an electronic objective optometry equipment, which is the product of the combination of refractive examination technology and electronic computer technology. The measurement does not require the subjective judgment of clinicians and subjects, and objectively evaluates refractive parameters through pre-set standards.
Because of the simplicity, speed and short learning period of computerized optometry, it is suitable for rapid acquisition and as a starting point for subjective optometry or for routine eye care screening.
With the application of high technology in computer refractometers, the accuracy of computer refractometers has been greatly improved. Many instruments integrate the functions of keratometer or corneal topography, and some manufacturers' instruments are automatically connected to the comprehensive refractometer. , the measurement results are directly imported into the comprehensive refractometer, which is convenient to use; the portable computer refractometer can also be used in the surgical process and screening.
Modern computerized refractometer designs typically have two main characteristics:
1. Adjustment control
Control of accommodation is especially important for most optometry methods. Almost all refractometers require the subject to look at the test cursor or cursor image, which stimulates the adjustment and results in overcorrection of myopia or undercorrection of hyperopia. Although the test cursor is designed to be at infinity through the optical path, because the instrument is very close to the subject. Therefore, during the design process, the test cursor is "fog-visualized", and before the measurement starts, the examinee first sees a "fog-visualized" cursor to relax conditioning, but cannot completely remove near-sensing conditioning.
2. The detection light is infrared light
The detection light of the currently used computer refractometers all use infrared light with a wavelength of 800-950 nm. The reasons are: ①Infrared rays are absorbed less by the tissues in the eye than visible light, and more light is reflected by the fundus. Therefore, it is more important to detect that the light energy loss of the light passing through the intraocular medium is less, especially for the eyes with the opacity of the refractive medium. ② For the inspected eye, the detection target and the detection light are invisible, which better overcomes the adjustment problem caused by the measurement of the target.
Due to different production companies, the design and structure of the computer refractometer are also different, and the examiner needs to read the instructions in detail before using the computer refractometer. The common structure of the computer refractometer is:
①The cursor that the examinee is looking at.
②The jaw rest and headrest can be adjusted to keep the patient's head position fixed during the examination.
③The joystick can be moved back and forth, up and down, left and right to adjust the focus and adjust the position of the subject's eyes.
④ The monitor displays the position of the eye to be examined and the measurement results.
⑤Printing device