CN102499627A - Objective eyesight detection method - Google Patents

Abstract

The invention relates to an objective eyesight detection method, belonging to the technical field of medical detection, which comprises the following steps that: human eye wavefront aberration measured by a human eye aberration instrument of a Shack-Hartmann wavefront sensor is input in a computer, and by utilizing the computer and applying matlab calculation software, a generalized pupil function of a human eye optical system is computed by the human eye wavefront aberration; an optical modulation transfer function (MTF) of the human eye optical system is calculated by the generalized pupil function of the human eye optical system in a self-correlation way; a human eye maximum spatial resolution f (circle/degree) can be obtained by a coordinate of the crossing point of the optical MTF of the human eye optical system and an aerial image modulation (AIM) curve; and the eyesight of the human eye is calculated according to the human eye maximum spatial resolution f (circle/degree). According to the invention, an eyesight detection result can be displayed in the compute, or stored in the compute, and can be printed.

Description

A kind of objective vision testing method

Technical field

The present invention relates to a kind of objective vision testing method, belong to technical field of medical detection.

Background technology

Eyes are most important organs that the mankind obtain external information, human when cognitive world around about 95% information source in vision.Visual performance comprises shape feel, stereoscopic vision, light sensation, the visual field and colour vision etc.And shape feels it is the visual system most important function, usually shape feel function with vision as the clinical evaluation index.The detection of vision, international popular adopts classical Snellen visual acuity chart to detect at present, and this detection method detection speed is slower; And be subjective; Require person under inspection's cooperation, testing result depends on detected person's cognition and states with main, when carrying out the occupational detection; Some detected person recites visual acuity chart in advance, makes testing result untrue.For young child, can not cooperate detection, can have some difficulties during detection, even can't detect, though the minority ophthalmologic hospital adopts graphical diagrams to detect children ' s vision now, but still before needing to detect child to be detected is trained.

Summary of the invention

For the employing visual acuity chart that overcomes existing subjectivity carries out the shortcoming of vision testing method, the invention provides a kind of objective vision testing method.This vision testing method can overcome cognition that testing result that the visual acuity chart detection method of existing subjectivity exists relies on the detected person and mainly state, detection speed waits shortcoming more slowly; Human eyesight is carried out objective, detection quickly and accurately, in several seconds, just can provide testing result.

The technical solution adopted for the present invention to solve the technical problems is:

At first utilize Shack-Hartmann wavefront sensor human eye aberration appearance to measure human eyes wave-front optical aberration; Provide the broad sense pupil function of opthalmic optics system by wave front aberration; Calculate the optical-modulation transfer function of opthalmic optics system by the self correlation of the broad sense pupil function of opthalmic optics system; The optical-modulation transfer function of opthalmic optics system and subretinal space obtain human eye maximum space resolution as the abscissa in the cross point of modulation degree curve, provide the vision of human eye according to the maximum space resolution of human eye.

Principle of the present invention:

Use Shack-Hartmann wavefront sensor human eye aberration appearance and measure the wave front aberration of the 2nd grade to the 10th grade of human eye Ze Nike (Zernike).Wave front aberration by the Zernike polynomial repressentation:

$W(x,y)=\underset{k}{\overset{k_{\max }}{\mathrm{\Σ}}}{C}_k{Z}_k(x,y)---\left(1\right)$

In (1) formula, Z _k(x y) is Zernike multinomial k item, C _kBe coefficient, k _MaxBe maximum item, the k here of blocking _Max=65.

Preceding two coefficient C ₁, C ₂Be whole inclination of wave front, do not influence optical property, therefore can ignore.

By wave front aberration W (x, y) the broad sense pupil function P of structure opthalmic optics system (x, y):

P(x，y)＝p(x，y)exp[iw(x，y)] (2)

Wherein: r is the pupil radius.

By the broad sense pupil function P of opthalmic optics system (x, self correlation y) calculate the optical transfer function (OTF) of opthalmic optics system:

OTF(x，y)＝∫P(x′，y′)P ^*(x′-x，y′-y)dx′dy′ (4)

The modulation transfer function (MTF) of opthalmic optics system is the mould of optical transfer function (OTF):

MTF＝|OTF| (5)

Optical-modulation transfer function of opthalmic optics system (MTF) and subretinal space as the abscissa in the cross point of modulation degree curve (AIM) be human eye maximum space resolution f (week/degree, cycle/deg).

(week/degree cycle/deg) can obtain the vision of human eye by the maximum space resolution f of human eye.External object is through the size sensation that eyes cause, it is big or small to be decided by that foreign object forms images on retina.Have according to geometric optical theory:

The sighting target of general visual acuity chart angle before eyes is all very little, and the tangent value of angle can be thought the radian value that equals angle, Here it is visual angle.Therefore sensuously the foreign object size just is decided by the size at contained visual angle.

The definition of vision: vision is exactly the ability that eyes can be differentiated minimum range between two object points, and weighs with the visual angle.Discernmible visual angle is more little, and vision is good more, thus express vision with the inverse at visual angle usually, so vision is the visual angle size of the minimum sighting target that be able to recognize of human eye, highly representes the visual angle size of sighting target with measuring distance and letter.That is:

Measuring distance be generally 20 feet or 6 meters (the U.S. with 20 feet as measuring distance, the country of other metric unit usually with 6 meters as measuring distance).Denominator " relative 5 minutes letter distance " is meant when measuring distance is 20 feet or 6 meters, the alphabetical pairing distance of relative 5 subangles of height of minimum that the tester can differentiate.Vision as 20/200 is represented: measuring distance is 20 feet, and the distance of relative 5 subangles of height of the discernmible minimum letter of tester is 200 feet.

Decimal vision symbol is to change mark into the decimal form.Vision as 20/200 is 0.1.

Human eye is when maximum space resolution f (cycle/deg), and the minimum angle that human eye can be differentiated is 1/f, and pairing height at 20 feet minimum letters of locating to differentiate is 2.5 * 20 * (1/f), and wherein 2.5 is that sighting target " E " is 2.5 cycles.

Relative 5 subangles of this alphabetical height, promptly the pairing distance L of 5/60 degree is:

$L=\frac{2.5\×20}{f\×\left(\frac{5}{60}\right)}---\left(8\right)$

Pairing vision is:

Vision (VA)=20/L=f/30 (9)

Specify embodiment of the present invention below in conjunction with accompanying drawing.

Description of drawings

Accompanying drawing 1 is the testing process figure of a kind of objective vision testing method of the present invention.

As shown in Figure 1, use Shack-Hartmann wavefront sensor human eye aberration appearance (1) and measure human eyes wave-front optical aberration (2).Shack-Hartmann wavefront sensor human eye aberration appearance (1) links to each other with computer (3); The human eyes wave-front optical aberration (2) that Shack-Hartmann wavefront sensor human eye aberration appearance (1) is measured is imported computer (3); Utilize computer (3); Use the matlab software for calculation; Calculate the broad sense pupil function (4) of opthalmic optics system by human eyes wave-front optical aberration (2); Calculate the optical-modulation transfer function MTF (5) of opthalmic optics system by the self correlation of the broad sense pupil function (4) of opthalmic optics system, obtain human eye maximum space resolution f (week/degree, cycle/deg) (7) by the optical-modulation transfer function MTF (5) of opthalmic optics system and subretinal space as the abscissa in the cross point of modulation degree curve A IM (6) again; (week/degree, cycle/deg) (7) provide the vision (8) of human eye according to the maximum space resolution f of human eye.Vision (8) testing result can show in computer, or is stored in the computer, also can print.

Claims (2)

1. an objective vision testing method is characterized in that: in the human eyes wave-front optical aberration input computer that Shack-Hartmann wavefront sensor human eye aberration appearance is measured.

2. a kind of objective vision testing method as claimed in claim 1; It is characterized in that: utilize computer; Use the matlab software for calculation, calculate the broad sense pupil function of opthalmic optics system, calculate the optical-modulation transfer function MTF of opthalmic optics system by the self correlation of the broad sense pupil function of opthalmic optics system by human eyes wave-front optical aberration; Obtain human eye maximum space resolution f (week/degree by the optical-modulation transfer function MTF of opthalmic optics system and subretinal space as the abscissa in the cross point of modulation degree curve A IM again; Cycle/deg), (week/degree cycle/deg) calculates the vision of human eye according to the maximum space resolution f of human eye.The vision testing result can show in computer, or is stored in the computer, also can print.

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