JPS6131153A - Laser apparatus for ophthalimic treatment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser device for ophthalmologic treatment in which an aiming beam for focusing and a main laser beam for treatment are expanded and matched.

Recently, high-power, short-pulse laser beams such as YAG lasers have been used in ophthalmic surgeries such as secondary cataract treatment, intrapupillary opacification membrane excision, and intravitreal myectomy, and have achieved good results. Using such a laser beam,
The high electric field generated by focusing the high-power light on the affected area can destroy the tissue in the affected area, and the resulting plasma causes the destroyed tissue to dissipate, while absorbing excess light and moving it away from the affected area. Posterior tissues can be protected.

YAG lasers are generally widely used as high-power, short-pulse laser beams for generating plasma, but other lasers such as ruby, YLF, and alexandrite can also be used. However, here, a case will be described in which a YAG laser is used as the main laser beam for treatment.

In general, the incident light will pass through the affected area and reach the tissue in the back until the plasma generated in the affected area by the laser beam develops enough to absorb the incident light. This can be avoided by keeping the power density at the tissue sufficiently low. In other words, the problem is how to focus the incident light on the target tissue of the affected area, and for this purpose the F value of the objective lens is made small to minimize the spread of the laser beam. However, as a result, the beam spot diameter becomes small and the depth of focus becomes shallow, making it extremely difficult to focus the device.

For these reasons, in this type of laser device for ophthalmic treatment, the type of aiming means is a factor that determines the quality of the device. In the conventional case, a He-He laser is generally used as the aiming beam, and it is necessary to judge whether or not it is in focus based on the size of its spot diameter, the point where the beams match, or the point at which the rotating beam spot stops moving. method is adopted. However, in the eye where ghost images occur due to various reflections, it is considered best to use a beam spot that rotates once.

One of the methods known in the past is to rotate a combination prism to rotate the aiming beam around the outer periphery of the main laser beam before aligning the aiming beam with the main laser beam. If there is even a slight eccentricity in the rotation axis, the aiming beams will not match at the focused position, and there is a high possibility that a focus deviation will occur, causing a problem in focusing accuracy.

A method has also been proposed in which the aiming beam and the main laser beam are expanded separately and the aiming beam is chopped into sectors, etc., but this method has the drawbacks of being structurally complex and increasing cost.

An object of the present invention is to provide a laser device for ophthalmic treatment which has almost no out-of-focus unlike the conventional ones and has a mechanically simple and inexpensive aiming means. A laser device for ophthalmologic treatment that uses a magnifying and matching aiming beam and a main laser beam for treatment, which includes a rotating filter and a fixed filter provided with a slit window that allows only the aiming beam to pass through a part of the outer periphery. These filters are arranged on the same axis so that their slit windows overlap, and when out of focus, the aiming beam is rotated and observed.

EMBODIMENT OF THE INVENTION Below, this invention is demonstrated in detail based on the Example of illustration.

Figure 1 shows the basic configuration of a laser device for ophthalmic treatment that uses a YAG laser as the main laser beam for treatment and a He-He laser as the aiming beam for focusing and positioning, and E is for treatment. e is the affected area to be treated, and e is the treated presbyopia. An ordinary slit lamp having an optical axis O1 is constituted by an objective lens l placed in front of the affected area E and an observation optical system 2, and the observation optical system 2 includes, from the objective lens 1 side, an image magnification variable optical system 3 and a relay lens. 4, a binocular prism 5 and an eyepiece lens 6 are arranged, and a filter 7 is provided in front of the observation optical system 2 to absorb the laser beam reflected from the affected area E etc. in order to protect the treated presbyopia e. In addition, 8 indicates a main laser consisting of a YAG laser that emits a main laser beam for treatment, and 9 indicates an auxiliary laser consisting of a He-Ne laser that emits an aiming beam B2 for focusing and positioning. The beam B2 is reflected by the total reflection mirror 10 and is matched with the main laser beam B1 by the semi-transparent member 11.

Here, as the semi-transparent member 11, for example, a cube reflector, a pellicle reflector, a half mirror, etc. is used, which has spectral characteristics of total reflection for the main laser beam Bl and transmission for the aiming beam B2. The main laser beam Bl and the aiming beam B2 that coincide with each other through the semi-transparent member 11 are expanded by a common beam expansion optical system 12, and then are aligned with the optical axis O1 of the filter 13 and the objective lens 1.
The light passes through a guichroic mirror 14 provided obliquely above and is focused by an objective lens onto a treatment target area Ea of the affected area E, for example, a posterior internal cataract membrane.

In addition, the guichroic mirror 14 is the main laser beam B.
It has the spectral characteristics of total reflection for B1, partial transmission for aiming beam B2, and transmission for visible light. Further, the filter 13 is transparent to the main laser beam Bl, but has a plurality of slit windows on the beam outer periphery for the aiming beam B2, as will be described later based on FIGS. 2 and 3. , the aiming beam B2 transmitted through this slit window appears to rotate. That is, after finding the treatment target region E♂ using the observation optical system 2 and setting the device at a position where the plurality of aiming beams B2 that appear to rotate become one and stop rotating, the main laser 8 is triggered. Then, several YAG laser beam pulses are emitted to destroy the treatment target area Ea.

FIGS. 2 and 3 show specific configuration examples of the filter 13 in FIG. 1, and FIG. 3 shows 11R2rgJ
FIG. 2 is a diagram seen from the beam traveling direction of the optical axis 02 of FIG. Here, two pairs of a rotary filter 15 and a fixed filter 16 are arranged coaxially on the optical axis 02, corresponding to the filter 13 in FIG. These filters 15 and 16 have transparent plates 15a and 18a made of anti-reflection coated glass, for example, and a film surface made of a dielectric multilayer film 5b.
.

A plurality of slit windows 15c and 16c are provided around the caps 1ii15b and 16b, respectively, and the slit window 15c has a larger diameter than the slit window 16c. Further, the film surfaces 15b and 16b have spectral characteristics that transmit the main laser beam Bl, but do not transmit the aiming beam B2 except for the slit windows 15c and 16c.

The slit windows 15c and 16c are both provided on the same circumference so that they can overlap each other. While the fixed filter 16 is fixed on the optical axis 02, the rotating filter 15 on the beam incidence side is rotatably held on the optical axis 02, and its rotation mechanism has a structure that does not block the laser beam. is necessary.

In the illustrated embodiment, the rotary filter 15 has a gear 17 on its outer periphery.
The rotary filter 15 is attached to an outer frame 18 having ing.

In this case, the other gear 20 plays a holding role as an idler gear simply supported by the frame 22.

It goes without saying that if the one-rotation filter 15 is held by three gears, it can be held more stably.

In the above configuration, the motor 21 rotates the rotary filter 1.
5 is rotated, the laser beam transmitted through the slit window 15c sequentially scans the slit window 16c of the fixed filter 16 in the rotation direction, and the laser beam passes through the slit window 18c in the periphery of the main laser beam in the cross-sectional direction. The aiming beam B2 will blink sequentially at the corresponding fixed portion. Here, as shown in FIG. 4, if the beam spot is out of focus, the beam spot will rotate, and once the focusing is completed, the beam spot will not move. In this case, since the slit window 15c has a larger diameter than the slit window 16c,
Light unevenness caused by rotational blurring of the rotating filter 15 can be removed.

Note that the number of slit windows 15c of the rotating filter 15 is an arbitrary number determined depending on the chopping frequency, but the number of slit windows 16c of the fixed filter 16 is determined in consideration of ease of observation. However, it is preferable to arrange four or more symmetrically as shown in the figure, as this will serve as a monitor to determine the position when vignetting occurs due to the eyelid or iris. be.

The example is aiming beam B2 and main laser beam B1.
Although the case where the beams B2 and B1 are expanded by the common beam expansion optical system 12 after being matched with each other is shown, the present invention can also be applied to a system in which the beams B2 and B1 are expanded independently and then matched with each other. Needless to say.

As explained above, the laser device for ophthalmic treatment according to the present invention can effectively eliminate the influence of rotational vibration of the rotating filter by providing a slit window in the rotating filter and the fixed filter. The mechanism allows for accurate positioning and focusing, making it possible to perform safe eye treatment.

[Brief explanation of the drawing]

The drawings show an embodiment of the ophthalmic treatment laser device according to the present invention, in which Fig. 1 is an optical layout diagram of the basic configuration, Fig. 2 is an enlarged view of the filter section, and Fig. 3 is an enlarged view of the filter section. The plan view of FIG. 4 is a diagram showing the principle of focusing. Reference numeral 1 is an objective lens, 2 is an observation optical system, and 8 is a main laser.
, 9 is an auxiliary laser, 11 is a reflecting member, 12 is a beam expansion optical system, 13 is a filter, 14 is a gyroic mirror, 15 is a rotating filter, 16 is a fixed filter, 15a
, 16a is a transparent plate, 15b, 16b are film surfaces, 15c, 1
6c is a slit window, and 21 is a motor. Patent applicant: Canon Corporation II Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. In a laser device for ophthalmic treatment that uses an aiming beam for focusing and a main laser beam for treatment to be expanded and matched, a slit that allows only the aiming beam to pass through a part of the outer periphery. It has a rotating filter with a window and a fixed filter, and these filters are arranged on the same axis so that the slit windows overlap, so that when the focusing beam is out of focus, the aiming beam is rotated and observed. A laser device for ophthalmological treatment. 2. The rotating filter and the fixed filter have spectral characteristics that completely transmit the main laser beam and do not transmit the aiming beam except for a slit window portion. A laser device for ophthalmic treatment as described in Section 1. 3. The laser device for ophthalmic treatment according to claim 1, wherein the slit window provided on the rotating filter is larger than the slit window provided on the fixed filter. 4. The laser device for eye treatment according to claim 1, wherein the rotary filter is held by at least two gears, one of which is rotationally driven, and the other is an idler gear.