JP4237533B2 - Ophthalmic equipment - Google Patents

Description

【００３５】
ここで、最適化で決定するパラメータは、ｋ_１、ｋ_２、ａ、ｂである。なお、それぞれの初期値は適当でも良いし、前出のアルゴリズムで利用した方法により決定してもよい。この関数形では、ブレークアップ開始時間はａに、ブレークアップ速度はｋ_２の最適化された値を採用する。
また、前出のアルゴリズムで出力が得られなかった場合に、その最終のフィッティングからｋ_１、ｋ_２、ａ、ｂを求め、このアルゴリズムの初期値として利用し、数式１の結果を出力する方法もある。
【００３６】
３−３．瞬きをトリガーにしてドライアイを解析する眼科測定
つぎに、瞬きをトリガーにしてドライアイを解析する眼科測定について説明する。
ステップＳ１０１及びＳ１０３は上述した通りである。ステップＳ１０５では、被検者は楽な状態で、瞬きも自然にするようにインストラクションされ、入力部６５０の測定開始ボタンが押される。つぎに、ステップＳ１０７及びＳ１０９では、演算部６００は、波面測定部６０１によりハルトマンの連続測定（１秒間隔）を開始する。さらに、ここで、波面測定部６０１は、前眼部の連続測定（１秒間隔）を開始し、毎回その明暗に関するヒストグラムをもとめ、これから瞬きを判断する。
【００３７】
図７に、瞬きの判定フローチャートを示す。また、図８及び図９に、瞬きしていないとき及び瞬き中のヒストグラムについての説明図をそれぞれ示す。図８及び図９で、（ａ）は前眼部像、（ｂ）はヒストグラムである。
【００３８】
瞬きの判定フローチャートが開始されると、演算部６００の判定部６０２は、取得した前眼部像のヒストグラムを計算する（Ｓ３０１）。判定部６０２は、ヒストグラムのピークが所定数（例、１５０）と比較する（Ｓ３０３）。ここで、ピークが所定数より大きい場合、瞬き中と判断し（図９参照）、一方、小さい場合、瞬きしていないと判断することができる（図８参照）。
【００３９】
つぎに、メインのフローに戻り、例えば、被験者に対しては、一回瞬きをしたあと、瞬きを我慢するように指示がでる。判定部６０２は、最後の瞬きの終了時間をｔ_０としたとき、ｔ_０から所定の時間が経過したら、ハルトマン及び前眼部の測定を終了する。
【００４０】
その後、ステップＳ１１３以降の処理では、演算部６００の判定部６０２は、ｔ_０から後の画像を使って、上述と同様に、前出のアルゴリズムで解析を行い、ブレークアップ開始時間と速度等のブレークアップに関する各値を求める。
【００４１】
図１０に、ブレークアップの測定例を示す。
この図は、複数の被験者に対して、本実施の形態の眼科装置によりブレークアップの状態を測定した結果である。図示のように、回帰直線によりブレークアップ開始時間等の各値が求められる。
【００４２】
なお、測定中のアライメントとしては、例えば、４０秒程度測定するので、アライメントはオートアライメントが好ましい。なお、測定者がマニュアルでアライメントを合わせる機構を備えてもよい。さらに、瞬きの回数をとることや、瞬きで涙液層が回復するが、それでもドライな部分があるかの測定を行うことにより、眼性疲労度を測定することもできる。
【００４３】
３−４．両眼同時測定例
図１３に、両眼同時測定のための眼科システム構成図を示す。この眼科システムは、図１の光学系１ａ及び１ｂを両眼１００ａ及び１００ｂに対して備え、それらが独立に調節可能とされ被検者の両眼に対してアライメントが可能となる。そして、上記までは片眼のみの測定であったが、同装置を２台用いる形で両眼同時に測定を行うこともできる。片眼測定であっても両眼開いていなければならず片眼測定後しばらくはもう片眼の測定を行うことができなかったが、この場合、両眼共確実に測定できるという利点がある。
【００４４】
４．ゼルニケ解析とＲＭＳ
つぎに、ゼルニケ解析について説明する。一般に知られているゼルニケ多項式からゼルニケ係数ｃ_ｉ ^２ｊ−ｉを算出する方法について説明する。ゼルニケ係数ｃ_ｉ ^２ｊ−ｉは、例えば、ハルトマン板２２を介して第１受光部２１で得られた光束の傾き角に基づいて被検眼１００の光学特性を把握するための重要なパラメータである。
被検眼１００の波面収差Ｗ（Ｘ，Ｙ）は、ゼルニケ係数ｃ_ｉ ^２ｊ−ｉ、ゼルニケ多項式Ｚ_ｉ ^２ｊ−ｉを用いて次式で表される。
【００４５】
【数２】

ただし、（Ｘ，Ｙ）はハルトマン板２２の縦横の座標である。
【００４６】
また、波面収差Ｗ（Ｘ，Ｙ）は、第１受光部２１の縦横の座標を（ｘ、ｙ）、ハルトマン板２２と第１受光部２１の距離をｆ、第１受光部２１で受光される点像の移動距離を（△ｘ、△ｙ）とすると、次式の関係が成り立つ。
【００４７】
【数３】

【００４８】
ここで、ゼルニケ多項式Ｚ_ｉ ^２ｊ−ｉは、以下の数式４及び数式５で表される。具体的には、図１１に、（ｒ，ｔ）座標のゼルニケ多項式の図、及び、図１２に、（ｘ，ｙ）座標のゼルニケ多項式の図をそれぞれ示す。
【００４９】
【数４】

【００５０】
【数５】

【００５１】
なお、ゼルニケ係数ｃ_ｉ ^２ｊ−ｉは、以下の数式６で表される自乗誤差を最小にすることにより具体的な値を得ることができる。
【００５２】
【数６】

【００５３】
ただし、Ｗ（Ｘ、Ｙ）：波面収差、（Ｘ、Ｙ）：ハルトマン板座標、（△ｘ、△ｙ）：第１受光部２１で受光される点像の移動距離、ｆ：ハルトマン板２２と第１受光部２１との距離。
【００５４】
演算部６００は、ゼルニケ係数ｃ_ｉ ^２ｊ−ｉを算出し、これを用いて球面収差、コマ収差、非点収差等の眼光学特性を求める。また、演算部６００は、ゼルニケ係数ｃ_ｉ ^２ｊ−ｉを用いて次式により収差量ＲＭＳ_ｉ ^２ｊ−ｉを算出する。
【００５５】
【数７】

【００５６】
５．高次の収差を用いたブレークアップ状態の解析
本実施の形態の眼科装置は、５次以上の高次の収差を用いてブレークアップ状態を解析することができる。
このように５次以上の高次の収差を用いる場合、第１変換部材２２は、被検眼網膜から反射して戻ってくる反射光束の一部を、該反射光束を少なくとも実質的に２１本のビームに変換する短焦点又は高密度のレンズ部を有するものを用いる。また、波面測定部６０１は、被検眼が瞬きした後の開始時点と、その後の所定期間、複数回の第１受光部２１の受光信号から少なくとも５次以上の高次収差を含む被検眼の収差成分を求める。判定部６０２は、波面測定部６０１の測定結果から５次以上の高次収差の時間的変化を比較することにより、ドライアイの状態を判断する。
ブレークアップ状態解析処理は、上述の各フローチャート及びその説明箇所で説明したものと同様である。ただし、５次以上の高次の収差を用いることを設定する処理を適宜のタイミングで実行する。例えば、図３のステップＳ１０３で、入力部６５０又はメモリ８００に予め定められた設定により、この処理を実行することができる。さらに、前述のブレークアップの測定例と所定の高次の収差を用いたブレークアップ測定例の複数を実行して、表示部７００に表示することもできる。
図１４は、ブレークアップの測定例を示す図である。
図１４（Ａ）は、３次及び４次の収差を用いた測定例を示し、図１４（Ｂ）は、５次及び６次の収差を用いた測定例を示す。図示のように、波面収差の時間的変化が、４次以下の収差よりも、５次以上の高次収差に顕著に影響される場合がある。このような場合、高次の収差を用いると、ブレークアップ（分割点）を一層明瞭に求めることができる。
【００５７】
【発明の効果】
本発明によると、以上のように、基本原理として、涙液層がドライアップすると波面収差が大きくなることを利用することにより、ドライアイの臨床に有効に用いることができる眼科測定装置を提供することができる。さらに、本発明によると、瞬きをカウントすることで目の疲労を考慮することができる眼科測定装置を提供することができる。
【図面の簡単な説明】
【図１】眼科装置の光学系の構成図。
【図２】眼科装置の電気系の構成図。
【図３】ドライアイの測定フローチャート。
【図４】ブレークアップ（分割点）を求めるための説明図。
【図５】ブレークアップを求めるための解析フローチャート。
【図６】ブレークアップを求めるための他の解析フローチャート。
【図７】瞬きの判定フローチャート。
【図８】瞬きしていないときのヒストグラムについての説明図。
【図９】瞬き中のヒストグラムについての説明図。
【図１０】ブレークアップの測定例。
【図１１】（ｒ，ｔ）座標のゼルニケ多項式の図。
【図１２】（ｘ，ｙ）座標のゼルニケ多項式の図。
【図１３】両眼同時測定のための眼科システム構成図。
【図１４】ブレークアップの測定例を示す図。
【符号の説明】
１０ 第１照明光学系
１１ 第１光源部
２０ 第１受光光学系
２１ 第１受光部
３０ 前眼部観察部
４０ 前眼部照明部
５０ 第１調整光学部
７０ 第２調整光学部
９０ 視標光学部
６００ 演算部
６０１ 波面測定部
６０２ 判定部
６１０ 制御部
６５０ 入力部
７００ 表示部
８００ メモリ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ophthalmologic apparatus, and more particularly, to an ophthalmologic apparatus for determining a dry eye state based on a result of measuring optical characteristics of an eye to be examined using a wavefront sensor.
[0002]
[Prior art]
Conventionally, as an ophthalmologic measurement apparatus related to dry eye, the following techniques can be cited.
Patent Document 1 describes an ophthalmologic measurement apparatus that quantitatively measures the fluorescence intensity from the cornea and tear fluid of a subject's eye instilled with a predetermined fluorescent agent. In Patent Document 2, it is possible to know the state of the lipid layer of the eye to be examined, the state of the tear fluid flow, etc. by observing the color image of the interference pattern due to the interference of the reflected light on the front and back surfaces of the lipid layer, An ophthalmologic apparatus is described that can easily perform a simple diagnosis of non-contact and local dry eye. Further, Patent Document 3 discloses a clear tear fluid that has no interference light in a wide observation field without causing vignetting in the observation field by allowing only signal light reflected from the tear film of the eye to be examined to enter the CCD. An ophthalmic tear observation device that can observe an interference pattern is described.
[Patent Document 1]
JP-A-6-277179 [Patent Document 2]
JP 7-136120 A [Patent Document 3]
Japanese Patent Laid-Open No. 8-52112
[Problems to be solved by the invention]
However, it cannot be said that the conventional ophthalmic measuring apparatus used in the clinical practice of dry eye sufficiently satisfies the requirements regarding the discrimination of the dry eye state.
In view of the above points, the present invention provides an ophthalmic measurement apparatus that can be used effectively in clinical practice of dry eye by utilizing the fact that wavefront aberration increases as the tear film dries up as a basic principle. For the purpose. Furthermore, an object of the present invention is to provide an ophthalmologic measurement apparatus that can take into account eye fatigue by counting blinks.
[0004]
[Means for Solving the Problems]
According to the first solution of the present invention,
An illumination optical system that makes the measurement light beam incident on the fundus of the eye to be examined;
A light receiving optical system that receives reflected light from the fundus of the eye to be examined; and
A light receiving unit that converts received light reflected by the light receiving optical system into an electrical signal;
A wavefront measurement unit for measuring a plurality of wavefront aberrations for a predetermined period of time;
A determination unit that determines the state of the dry eye based on a temporal change in the measurement result of the wavefront aberration of a plurality of times;
Is provided.
According to the second solution of the present invention,
An illumination optical system that makes the measurement light beam incident on the fundus of the eye to be examined;
A light receiving optical system that receives light through a conversion member that converts reflected light from the fundus of the eye to be examined into a number of light beams;
A light receiving unit that converts received light reflected by the light receiving optical system into an electrical signal;
A wavefront measuring unit for obtaining an aberration component of the subject eye including at least a fifth-order or higher order aberration from a light reception signal of the light receiving unit a plurality of times after a start time after the eye blinks; and a predetermined period thereafter;
An ophthalmologic apparatus is provided that includes a determination unit that determines the state of a dry eye based on a temporal change of a fifth-order or higher order aberration from the measurement result of the wavefront measurement unit.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
1. Optical System Configuration FIG. 1 shows a configuration diagram of an optical system of an ophthalmologic apparatus.
The ophthalmologic apparatus includes a first illumination optical system 10, a first light source unit 11, a first measurement unit 25, an anterior ocular segment illumination unit 30, an anterior ocular segment observation unit 40, a first adjustment optical unit 50, A second adjustment optical unit 70 and a target optical unit 90 are provided. The first measurement unit 25 includes a first light receiving optical system 20 and a first light receiving unit 21. For the eye 100, the retina (fundus) and cornea (anterior eye) are shown.
[0006]
Hereinafter, each part will be described in detail.
The first illumination optical system 10 is for illuminating a minute region on the fundus of the eye 100 to be examined with the light flux from the first light source unit 11. The first illumination optical system 10 includes, for example, a condenser lens, a variable cylinder lens, and a relay lens.
[0007]
The first light source unit 11 emits a light beam having a first wavelength. The first light source unit 11 preferably has high spatial coherence and not high temporal coherence. Here, as an example, the first light source unit 11 employs an SLD (super luminescence diode), and a point light source with high luminance can be obtained. The first light source unit 11 is not limited to the SLD, and even if it has a high coherence in both space and time, such as a laser, the first light source unit 11 can be appropriately inserted by inserting a rotating diffusion plate, a declination prism (D prism), or the like. It can be used by reducing the time coherence. And even if the LED does not have high coherence in space and time, it can be used by inserting a pinhole or the like at the position of the light source in the optical path as long as the amount of light is sufficient. Moreover, the wavelength of the 1st light source part 11 for illumination can use the wavelength (for example, 780 nm) of an infrared region, for example.
[0008]
The first light receiving optical system 20 is for receiving, for example, a light beam reflected and returned from the retina of the eye 100 to be guided to the first light receiving unit 21. The first light receiving optical system 20 includes, for example, a first conversion member 22 (eg, a Hartmann plate), an afocal lens, a variable cylinder lens, and a relay lens. The first conversion member 22 is a wavefront conversion member having a lens unit for converting the reflected light beam into at least 17 plural beams. For the first conversion member 22, a plurality of micro Fresnel lenses arranged in a plane orthogonal to the optical axis can be used. The first conversion member 22 may have a short-focus or high-density lens unit in addition to a long-focus or high-sensitivity member. The reflected light from the fundus is collected on the first light receiving unit 21 via the first conversion member 22. The first light receiving unit 21 receives the light from the first light receiving optical system 20 that has passed through the first conversion member 22 and generates a first signal. Note that the front focal point of the afocal lens 42 substantially coincides with the pupil of the eye 100 to be examined.
[0009]
The moving unit 15 integrally moves a portion surrounded by a dotted line in FIG. 1 including the first illumination optical system 10 and the first light receiving optical system 20. For example, assuming that the light beam from the first light source unit 11 is reflected at the point where it is collected, the first light receiving unit 21 maintains the relationship in which the signal peak at the first light receiving unit 21 due to the reflected light is maximized. It moves to the direction where the signal peak becomes strong, and can stop at the position where the intensity becomes maximum. Further, the first illumination optical system 10 and the first light receiving optical system 20 are moved separately. For example, assuming that the light beam from the first light source unit 11 is reflected at the point where the light is condensed, the first light receiving unit by the reflected light is used. It is also possible to maintain the relationship in which the signal peak at 21 is maximized, move in the direction in which the signal peak at the first light receiving unit 21 becomes stronger, and stop at the position where the intensity is maximized.
[0010]
Incident light from the first light source unit 11 to the subject's eye 100 decenters the diaphragm 12 to change the incident position of the light beam in a direction orthogonal to the optical axis, thereby preventing the reflection of the apex of the lens and cornea and suppressing noise. The diaphragm 12 has a diameter smaller than the effective range of the Hartmann plate 22 and can perform so-called single-pass aberration measurement in which the aberration of the eye affects only the light receiving side.
[0011]
Note that the incident light beam emitted from the first light source unit 11 follows the same way as the measurement light beam diffusely reflected from the fundus after paraxially after the measurement light beam diffusely reflected from the fundus occupies a common optical path. To do. However, in the single pass measurement, the diameters of the respective light beams are different, and the beam diameter of the incident light beam is set to be considerably smaller than the measurement light beam. Specifically, the beam diameter of the incident light beam may be, for example, about 1 mm at the pupil position of the eye 100 to be examined, and the beam diameter of the measurement light beam may be about 7 mm. Note that double-pass measurement can also be performed by appropriately arranging the optical system.
[0012]
The anterior ocular segment illumination unit 30 includes a second light source unit 31 that emits a light beam having a second wavelength, and the light beam from the second light source unit 31 forms a predetermined pattern on the anterior eye part using, for example, platid ring or kerat ring. Irradiate with. In the case of keratoling, a pattern only near the center of curvature of the cornea can be obtained from the kerato image. The second wavelength of the light beam emitted from the second light source unit 31 is different from, for example, the first wavelength (here, 780 nm), and a long wavelength can be selected (for example, 940 nm).
[0013]
The anterior ocular segment observation unit 40 includes, for example, a third light receiving unit 41 including a relay lens, a telecentric diaphragm, and a CCD. For example, the pattern of the anterior ocular segment illumination unit 30 such as platid ring and kerat ring is measured. The light flux reflected and returned from the anterior segment of the eye 100 is observed. The telecentric diaphragm is a diaphragm for preventing the anterior segment image from being blurred.
[0014]
For example, the first adjustment optical unit 50 mainly adjusts the working distance, and includes a light source unit, a condensing lens, and a light receiving unit. Here, the working distance adjustment is performed, for example, by irradiating a parallel light beam near the optical axis emitted from the light source unit toward the eye 100 to be measured and condensing the light reflected from the eye 100 to be measured. This is performed by receiving light at the light receiving unit through the lens. When the eye to be measured 100 is at an appropriate working distance, a spot image from the light source unit is formed on the optical axis of the light receiving unit. On the other hand, when the eye to be measured 100 deviates back and forth from an appropriate working distance, the spot image from the light source unit is formed above or below the optical axis of the light receiving unit. The light receiving unit only needs to be able to detect a change in the light beam position in the plane including the light source unit, the optical axis, and the light receiving unit. For example, a one-dimensional CCD, a position sensing device (PSD), etc. arranged in the plane. Can be applied.
[0015]
The beam splitter 61 is constituted by, for example, a dichroic mirror that reflects a light beam having a first wavelength and transmits a light beam having a second wavelength. In addition, a rotary prism 62 is provided for uniformizing light caused by uneven reflection from the fundus. The beam splitter 63 is configured by a mirror (for example, a polarization beam splitter) that reflects the light beam from the first light source unit 11 and transmits the light beam reflected and returned by the retina of the eye 100 to be examined.
[0016]
For example, the second adjustment optical unit 70 performs alignment adjustment in the X and Y directions, and includes an alignment light source unit, a lens, and a beam splitter.
The target optical unit 90 includes, for example, a landscape chart of the eye 100 to be examined, an optical path for projecting a target for fixation or clouding, and includes a light source unit (for example, a lamp), a fixation target 92, A relay lens is provided. The fixation target 92 can be irradiated to the fundus with the light flux from the light source unit, and the image to be examined 100 is observed.
[0017]
Although the above-described optical system has been described mainly as a single path with a thin incident light beam, the present invention can also be applied to an eye-specific measuring device as a double path with a large incident light beam. At this time, the optical system is arranged in a double-pass configuration, but the measurement / calculation processing by the calculation unit is the same.
[0018]
(Conjugate relationship)
The fundus of the eye 100 to be measured, the fixation target 92 of the target optical unit 90, the first light source unit 11, and the first light receiving unit 21 are conjugate. Further, the pupil (iris) of the eye 100 to be measured, the rotary prism 62, the conversion member (Hartmann plate) 22 of the first light receiving optical system, and the stop 12 on the measurement light incident side of the first illumination optical system 10 are conjugate. .
[0019]
2. Electrical System Configuration FIG. 2 is a configuration diagram of the electrical system of the ophthalmologic apparatus.
The configuration of the electrical system of the ophthalmologic apparatus includes a calculation unit 600, a control unit 610, an input unit 650, a display unit 700, a memory 800, a first drive unit 910, a second drive unit 911, and a third drive. A unit 912 and a fourth driving unit 913. The input unit 650 includes a pointing device for designating appropriate buttons, icons, positions, areas, and the like displayed on the display unit 700, a keyboard for inputting various data, and the like.
[0020]
The calculation unit 600 includes a wavefront measurement unit 601 and a determination unit 602. The wavefront measuring unit 601 performs wavefront aberration measurement a plurality of times for a predetermined period. The determination unit 602 determines the dry eye state by comparing temporal changes in the measurement results of a plurality of wavefront aberrations.
[0021]
The calculation unit 600 receives the first signal (4) from the first light receiving unit 21, the signal (7) from the anterior ocular segment observation unit 40, and the signal (10) from the first adjustment optical unit 50. Is done. The calculation unit 600 inputs the first signal (4) from the first light receiving unit 21 and the signal (7) from the anterior segment observation unit 40, and, for example, the optical characteristics of the eye 100 to be measured based on the tilt angle of the luminous flux. Ask for. The calculation unit 600 appropriately outputs signals or other signals / data corresponding to the calculation results to the control unit 610 that controls the electric drive system, the display unit 700, and the memory 800, respectively.
[0022]
The control unit 610 controls turning on and off of the first light source unit 11 and the second light source unit 31 and controls the first driving unit 910 to the fourth driving unit 913 based on a control signal from the calculation unit 600. Is for. For example, the control unit 610 outputs a signal (1) to the first light source unit 11 and a signal (5) to the second adjustment optical unit 70 based on a signal according to the calculation result in the calculation unit 600. Is output to the anterior segment illumination unit 30, and signals 8 and 9 are output to the first adjustment optical unit 50 to the target optical unit 90. The signal (11) is output, and further, the signal is output to the first driving unit 910 to the fourth driving unit 913.
[0023]
The first drive unit 910 outputs a signal (2) based on the signal (4) from the first light receiving unit 21 input to the calculation unit 600, and the variable cylinder lens of the first illumination optical system 10; The variable cylinder lens of the first light receiving optical system 20 is rotated by driving an appropriate lens moving means. This variable cylinder lens may be omitted.
[0024]
For example, the second drive unit 911 moves the first illumination optical system 10 and the first light reception optical system 20 in the optical axis direction based on the light reception signal (4) from the first light reception unit 21 input to the calculation unit 600. The moving unit 15 outputs the signal (3) to the moving unit 15 and drives the lens moving means of the moving unit 15. By moving the first light receiving optical system 20 in the optical axis direction, low-order aberrations can be compensated.
[0025]
For example, the third drive unit 912 moves the target optical unit 90 and outputs a signal (12) to an appropriate moving unit (not shown) and drives the moving unit. The fourth drive unit 913 rotates the rotary prism 62, outputs a signal (13) to an appropriate lens moving unit (not shown), and drives the lens moving unit.
[0026]
3. Measurement flowchart 3-1. Dry Eye Measurement Flowchart FIG. 3 shows a dry eye measurement flowchart.
When the subject comes to the measurement position and measurement is started, the ophthalmologic measurement apparatus is aligned at a position where the eye can be measured (S101). This alignment may be manual or automatic. Next, the computing unit 600 performs initial setting of the apparatus by the wavefront measuring unit 601 (S103). For example, the wavefront measuring unit 601 sets the measurement interval to 1 second and the measurement time to 40 seconds. The input unit 650 or the calculation unit 600 triggers to start measurement (S105). The trigger can be set in advance, for example, the operation of the measurement start button by the operator, the measurement of the blink after the measurement start button, and the measurement start at the timing. According to the trigger, the wavefront measuring unit 601 measures wavefront aberration (S107). Here, the calculation unit 600 repeats the measurement of the wavefront aberration until the measurement end time is reached by the wavefront measurement unit 601 (S109). If blinking occurs before the measurement end time is reached, the measurement ends at that point. The calculation unit 600 ends the measurement when the measurement end time is reached (S111).
[0027]
Next, the determination unit 602 of the calculation unit 600 analyzes a breakup state, which is one index for determining the dry eye state (S113). This detailed process will be described later. The determination unit 602 obtains values such as a breakup time (start time), a breakup speed, a breakup amount, and a breakup rate based on the breakup state, outputs them to the display unit 700, and stores them in the memory 800 (S115). ). Next, the determination unit 602 performs automatic diagnosis on dry eye based on the obtained values relating to breakup, outputs the dry eye to the display unit 700, and stores it in the memory 800 (S117). For this automatic diagnosis of dry eye, for example, according to a predetermined setting, (1) the break-up start point is early, (2) the break-up rate is high, or (3) both are judged and (1 ) To (3) can be made dry eye if they exceed a certain boundary. Thus, the process ends. During this measurement, it is possible to take into consideration that eye irritation is suppressed by eye drop anesthesia and the like, and blinking is not caused.
[0028]
3-2. Breakup State Analysis FIG. 4 is an explanatory diagram for obtaining a breakup (division point).
In this figure, the horizontal axis represents the number of measurements, and the vertical axis represents the RMS of higher-order aberrations. In the figure, the dividing point is the starting point of the tear film breakup. The left side of the dividing point is set to a steady state of tears, and the slope of the regression line at this time is set to a steady state (an inclination of 0 is ideal). On the other hand, the right side of the dividing point is in a break-up state. For example, the slope of the regression line in this region can be used as the breakup rate.
[0029]
FIG. 5 shows an analysis flowchart for obtaining a breakup. Here, the determination unit 602 of the calculation unit 600 can obtain a breakup as shown in FIG. 4 by approximating the measurement data to two straight lines.
[0030]
When the process is started, for example, the determination unit 602 sets the data to x _i and y _i and sets the total number of data to N (S201). The determination unit 602 draws a regression line on the entire data (S203). For example, the determination unit 602 draws a straight line parallel to the regression line including the data points, which is the bottom (or a predetermined number from the bottom). Here, the determination unit 602 sets the data point targeted at this time as the division point A, and sets the coordinates in the graph as (ax, ay) (S205). Further, the determination unit 602 draws regression lines on the left and right sides with the dividing point as a boundary, RL (x) and RR (x) are the regression lines, SL and SR are the slopes, and BL is the intercept. It is set as BR (S207). The determination unit 602 calculates a square error between the regression line and the measurement point (S209). For example, the determination unit 602 can calculate the square errors ResL and ResR with the left and right regression lines, respectively, as in the following equations.
ResL = Σ (yi−RL (xi)) ² ({i | i of data point on the left side of ax)}
ResR = Σ (yi−RR (xi)) ² ({i | i of data point on the right side of ax)}
[0031]
When the calculated ResL and / or ResR exceeds a predetermined value (S211), the determination unit 602 displays on the display unit 700 that automatic analysis is impossible (S213), and performs processing. finish. On the other hand, when ResL and / or ResR are equal to or less than a specified value (S211), and further, when the angle difference between SRs between SL is a predetermined value (for example, 2 degrees) or less (S215), the determination unit 602 automatically The fact that the analysis is impossible is displayed on the display unit 700 (S217), and the process is terminated. On the other hand, when the angle difference between the SRs between SL exceeds a predetermined value (S215), the determination unit 602 obtains and displays each value related to the breakup, with the time at the dividing point as the breakup start time and SR as the breakup speed. The data is displayed on the unit 700 and stored in the memory 800 (S219). Furthermore, the operator may finally confirm visually on the display unit 700, and the dividing point may be moved by the input unit 650.
[0032]
Next, FIG. 6 shows another analysis flowchart for obtaining a breakup. Here, the determination unit 602 approximates the measurement data to the function f (x).
[0033]
When the process is started, the determination unit 602 selects the function F (x, pj) defined in the range to be fitted (S251). Note that x is a horizontal axis of the graph, and pj is a parameter (a plurality may be obtained) obtained by optimization. Next, the determination unit 602 obtains a parameter pj that minimizes the square error between this function and the actual measurement value by a generally known attenuation least square method (nonlinear optimization method) (S253). Next, the determination unit 602 obtains values related to the breakup such as the breakup start time and the breakup speed according to the function f (x) determined by the obtained parameters (S255). These values can be determined as appropriate according to the form of f (x). Thus, the process ends.
As an example of the function form, there is a broken line as shown in the following equation.
[0034]
[Expression 1]

[0035]
Here, the parameters determined by the optimization are k ₁ , k ₂ , a, and b. Each initial value may be appropriate or determined by the method used in the above algorithm. This functional form, break-up start time to a, breakup rate adopts the optimized value of k _2.
Also, when no output is obtained by the above algorithm, k ₁ , k ₂ , a, b are obtained from the final fitting and used as initial values of this algorithm, and the result of Equation 1 is output. There is also.
[0036]
3-3. Ophthalmic Measurement for Analyzing Dry Eye with Blink as Trigger Next, ophthalmic measurement for analyzing dry eye with blink as a trigger will be described.
Steps S101 and S103 are as described above. In step S <b> 105, the subject is in an easy state and instructions are given to make blinking natural, and the measurement start button of the input unit 650 is pressed. Next, in steps S <b> 107 and S <b> 109, the calculation unit 600 starts Hartmann's continuous measurement (1 second interval) by the wavefront measurement unit 601. Further, here, the wavefront measuring unit 601 starts continuous measurement (1 second interval) of the anterior eye part, obtains a histogram regarding the brightness and darkness every time, and determines blinking from this.
[0037]
FIG. 7 shows a flowchart for determining blinking. FIGS. 8 and 9 are explanatory diagrams of histograms when the blinking is not occurring and during the blinking, respectively. 8 and 9, (a) is an anterior ocular segment image, and (b) is a histogram.
[0038]
When the blink determination flowchart is started, the determination unit 602 of the calculation unit 600 calculates a histogram of the acquired anterior ocular segment image (S301). The determination unit 602 compares the histogram peaks with a predetermined number (eg, 150) (S303). Here, when the peak is larger than the predetermined number, it is determined that blinking is occurring (see FIG. 9), while when it is small, it can be determined that blinking is not occurring (see FIG. 8).
[0039]
Next, returning to the main flow, for example, the subject is instructed to bear the blink after blinking once. Judging unit 602, the end time of the last blink when the t _0, after a lapse of a predetermined time from t _0, and terminates the measurement of the Hartmann and anterior segment.
[0040]
Thereafter, in the process step S113 and later, the determination unit 602 of the arithmetic unit 600 uses the image after the t _0, in the same manner as described above, analyzed in the preceding algorithm, such as break-up start time and speed Find each value for breakup.
[0041]
FIG. 10 shows an example of breakup measurement.
This figure is the result of measuring the break-up state for a plurality of subjects using the ophthalmologic apparatus of the present embodiment. As shown in the figure, each value such as the breakup start time is obtained from the regression line.
[0042]
As the alignment during the measurement, for example, since the measurement is performed for about 40 seconds, the alignment is preferably auto alignment. Note that a measurer may have a mechanism for manually aligning the alignment. Furthermore, it is possible to measure the degree of eye fatigue by measuring the number of blinks or by measuring whether the tear film is recovered by blinking but still has a dry part.
[0043]
3-4. Binocular Simultaneous Measurement Example FIG. 13 shows a configuration diagram of an ophthalmic system for simultaneous binocular measurement. This ophthalmic system includes the optical systems 1a and 1b of FIG. 1 for both eyes 100a and 100b, which can be independently adjusted, and alignment with both eyes of a subject is possible. And until now, only one eye has been measured, but it is also possible to measure both eyes simultaneously by using two of the same devices. Even in single-eye measurement, both eyes must be open, and one eye cannot be measured for a while after the single-eye measurement. In this case, there is an advantage that both eyes can be measured reliably.
[0044]
4). Zernike analysis and RMS
Next, Zernike analysis will be described. A method for calculating the Zernike coefficients c _i ^2j-i from a generally known Zernike polynomial will be described. The Zernike coefficient c _i ^2j−i is an important parameter for grasping the optical characteristics of the eye 100 to be inspected based on, for example, the tilt angle of the light beam obtained by the first light receiving unit 21 via the Hartmann plate 22.
The wavefront aberration W (X, Y) of the eye 100 to be examined is expressed by the following equation using the Zernike coefficient c _i ^2j−i and the Zernike polynomial Z _i ^2j−i .
[0045]
[Expression 2]

However, (X, Y) are the vertical and horizontal coordinates of the Hartmann plate 22.
[0046]
The wavefront aberration W (X, Y) is received by the first light receiving unit 21 with the vertical and horizontal coordinates of the first light receiving unit 21 being (x, y), the distance between the Hartmann plate 22 and the first light receiving unit 21 being f. If the moving distance of the point image is (Δx, Δy), the following relationship is established.
[0047]
[Equation 3]

[0048]
Here, the Zernike polynomial Z _i ^2j−i is expressed by the following equations 4 and 5. Specifically, FIG. 11 shows a Zernike polynomial of (r, t) coordinates, and FIG. 12 shows a Zernike polynomial of (x, y) coordinates.
[0049]
[Expression 4]

[0050]
[Equation 5]

[0051]
The Zernike coefficient c _i ^2j−i can be obtained as a specific value by minimizing the square error expressed by the following Equation 6.
[0052]
[Formula 6]

[0053]
Where W (X, Y): wavefront aberration, (X, Y): Hartmann plate coordinates, (Δx, Δy): movement distance of the point image received by the first light receiving unit 21, f: Hartmann plate 22 And the distance between the first light receiving unit 21 and the first light receiving unit 21.
[0054]
The calculation unit 600 calculates Zernike coefficients c _i ^2j−i and uses them to obtain eye optical characteristics such as spherical aberration, coma aberration, and astigmatism. In addition, the calculation unit 600 calculates the aberration amount RMS _i ^2j−i using the Zernike coefficient c _i ^{2j−i according} to the following equation.
[0055]
[Expression 7]

[0056]
5. Analysis of Breakup State Using Higher Order Aberration The ophthalmologic apparatus according to the present embodiment can analyze the breakup state using higher order aberrations of the fifth order or higher.
When the fifth-order or higher-order aberration is used as described above, the first conversion member 22 converts a part of the reflected light beam reflected from the retina of the eye to be examined, and at least substantially 21 of the reflected light beam. A lens having a short focal point or a high-density lens part to be converted into a beam is used. The wavefront measuring unit 601 also includes an aberration of the eye to be inspected that includes at least a fifth-order or higher order aberration from a light reception signal of the first light receiving unit 21 a plurality of times after the start time after the eye has blinked and for a predetermined period thereafter. Find the ingredients. The determination unit 602 determines the dry eye state by comparing temporal changes in the fifth and higher order aberrations from the measurement result of the wavefront measurement unit 601.
The breakup state analysis process is the same as that described in the above-described flowcharts and the description thereof. However, the process for setting the use of the fifth or higher order aberration is executed at an appropriate timing. For example, in step S103 of FIG. 3, this process can be executed by setting predetermined in the input unit 650 or the memory 800. Furthermore, a plurality of the above-described breakup measurement examples and breakup measurement examples using a predetermined higher-order aberration can be executed and displayed on the display unit 700.
FIG. 14 is a diagram illustrating a breakup measurement example.
FIG. 14A shows a measurement example using third-order and fourth-order aberrations, and FIG. 14B shows a measurement example using fifth-order and sixth-order aberrations. As shown in the figure, the temporal change of the wavefront aberration may be more significantly affected by the fifth and higher order aberrations than the fourth and lower order aberrations. In such a case, a breakup (division point) can be obtained more clearly by using higher-order aberrations.
[0057]
【The invention's effect】
According to the present invention, as described above, an ophthalmic measuring apparatus that can be effectively used in clinical practice of dry eye is provided by utilizing the fact that wavefront aberration increases as the tear film dries up as described above. be able to. Furthermore, according to the present invention, it is possible to provide an ophthalmologic measurement apparatus that can consider eye fatigue by counting blinks.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an optical system of an ophthalmologic apparatus.
FIG. 2 is a configuration diagram of an electrical system of the ophthalmologic apparatus.
FIG. 3 is a measurement flowchart of dry eye.
FIG. 4 is an explanatory diagram for obtaining a breakup (division point).
FIG. 5 is an analysis flowchart for obtaining a breakup.
FIG. 6 is another analysis flowchart for obtaining a breakup.
FIG. 7 is a flowchart for determining blinking.
FIG. 8 is an explanatory diagram of a histogram when there is no blink.
FIG. 9 is an explanatory diagram of a histogram during blinking.
FIG. 10 is a measurement example of breakup.
FIG. 11 is a diagram of a Zernike polynomial in (r, t) coordinates.
FIG. 12 is a diagram of a Zernike polynomial in (x, y) coordinates.
FIG. 13 is a block diagram of an ophthalmic system for simultaneous binocular measurement.
FIG. 14 is a diagram showing a measurement example of breakup.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 1st illumination optical system 11 1st light source part 20 1st light reception optical system 21 1st light reception part 30 Anterior eye part observation part 40 Anterior eye part illumination part 50 1st adjustment optical part 70 2nd adjustment optical part 90 Target optics Unit 600 arithmetic unit 601 wavefront measurement unit 602 determination unit 610 control unit 650 input unit 700 display unit 800 memory

Claims (15)

An illumination optical system that makes the measurement light beam incident on the fundus of the eye to be examined;
A light receiving optical system that receives reflected light from the fundus of the eye to be examined; and
A light receiving unit that converts received light reflected by the light receiving optical system into an electrical signal;
A wavefront measurement unit for measuring a plurality of wavefront aberrations for a predetermined period of time;
A determination unit that determines the state of the dry eye based on a temporal change in the measurement result of the wavefront aberration of a plurality of times;
Ophthalmic device equipped with. The ophthalmic device according to claim 1,
The illumination optical system illuminates a minute area on the eye retina with a light beam from a light source unit that emits a light beam of a first wavelength,
The light receiving optical system includes a first lens portion having a long focal point or a high sensitivity that converts a part of a reflected light beam reflected and returned from the retina of the eye to be examined into at least substantially 17 beams. An ophthalmologic apparatus characterized by receiving light at a light receiving portion through a conversion member.   The ophthalmologic apparatus according to claim 1, wherein the determination unit determines a function that fits a measurement result and obtains a value related to a breakup for determining a dry eye state. 4. The ophthalmologic apparatus according to claim 3 , wherein the break-related value includes one or more of a breakup start time, a breakup speed, a breakup amount, and a breakup rate. The ophthalmic device according to claim 1,
The determination unit further detects blinks,
The ophthalmologic apparatus, wherein the wavefront measurement unit measures wavefront aberration after a predetermined time from the blink detected by the determination unit. The ophthalmologic apparatus according to claim 5 , wherein the determination unit detects blinking based on an anterior ocular segment image.   The ophthalmic apparatus according to claim 1, wherein wavefront aberration measurement is performed simultaneously for both eyes. An illumination optical system that makes the measurement light beam incident on the fundus of the eye to be examined;
A light receiving optical system that receives light through a conversion member that converts reflected light from the fundus of the eye to be examined into a number of light beams;
A light receiving unit that converts received light reflected by the light receiving optical system into an electrical signal;
A wavefront measuring unit for obtaining an aberration component of the subject eye including at least a fifth-order or higher order aberration from a light reception signal of the light receiving unit a plurality of times after a start time after the eye blinks; and a predetermined period thereafter;
An ophthalmologic apparatus comprising: a determination unit that determines a dry eye state based on a temporal change of a fifth-order or higher order aberration from a measurement result of the wavefront measurement unit. The ophthalmic device according to claim 8 .
The illumination optical system illuminates a minute area on the eye retina with a light beam from a light source unit that emits a light beam of a first wavelength,
The light receiving optical system includes a lens unit having a high spatial resolution on the pupil, which converts a part of the reflected light beam reflected and returned from the retina of the eye to be examined into at least substantially 21 beams. An ophthalmologic apparatus, wherein the light receiving unit receives light through a first conversion member. The ophthalmologic apparatus according to claim 8 , wherein the dry eye state determined by the determination unit includes a breakup situation. The ophthalmologic apparatus according to claim 8 , wherein the determination unit determines a function that fits a measurement result and obtains a value related to a breakup for determining a dry eye state. 12. The ophthalmologic apparatus according to claim 11 , wherein the value relating to the breakup includes one or more of a breakup start time, a breakup speed, a breakup amount, and a breakup rate. The ophthalmic device according to claim 8 .
The determination unit further detects blinks,
The ophthalmologic apparatus, wherein the wavefront measurement unit measures wavefront aberration after a predetermined time from the blink detected by the determination unit. The ophthalmologic apparatus according to claim 13 , wherein the determination unit detects blinking based on an anterior ocular segment image. The ophthalmologic apparatus according to claim 8 , wherein wavefront aberration measurement is performed simultaneously on both eyes.

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