Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-09-01
2001-11-06
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06312128
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to microscopes for ophthalmologic surgery and more specifically to a focus light for the same.
BACKGROUND OF THE INVENTION
Many ophthalmologic surgical procedures require the use of a microscope for the performance thereof. A conventional ophthalmologic microscope has one or more objective lenses (depending on whether it is a binocular microscope) and an illumination source. It is also well known in the art to include a gaze-fixing device with the microscope to keep the patients focus in one particular position while the surgery is performed. Often the gaze-fixing device uses the same light as the illumination source. Sometimes, the gaze-fixing light is directed through the object lens of the microscope.
It is also known to include a gaze-fixing device consisting of a light emitting diode (LED) located between the objective lens and the patient's eye, but within the light ray path of the object lens, such as that taught by Takagi et al. in U.S. Pat. No. 4,793,700. Takagi teaches a red LED focus light as a gaze-fixing device located in an optical axis of the microscope, which is particularly important in radial keratotomy (RK) surgery. The illumination source in Takagi is of the conventional type, whereby the light passes through the one of the object lenses, albeit a few degrees off of the optical axis.
Another problem with ophthalmologic microscopes is that the intense illumination source over the course of a surgical procedure, such as a cataract removal, can cause photophobia and/or phototoxicity, possibly causing a burn on the retina. This is especially true when the eye of the patient is focused in the same general direction as the illumination source, as is the case with conventional microscopes. The light from the illumination source hits the retina on the macula, which is particularly light sensitive and probably the most important part of the retina for vision.
It is known to reroute a significant portion of the illumination source so that it hits the patient's eye at an angle. This causes much of the high intensity light to hit the retina in less photosensitive areas than the macula. Such a solution is disclosed in U.S. Pat. No. 5,155,509 to Kleinberg. Such solutions are not ideal, however, because it is preferable for many types of surgery to retain a majority of the illumination source close to the visual axis of the microscope, as is the case with conventional microscopes. These solutions also lack a gaze-fixing device to keep the patient's eye from moving. Furthermore, these solutions require a complex array of mirrors and want for simplification.
Takagi purports to reduce excessive stimulus of light on the macula with the gaze-fixing device. Although such exposure may be reduced somewhat, the illumination source is still directed through the object lens, and thus not sufficiently off-angle from the optic axis to hit the insensitive optic nerve.
Thus, it is an object of the present invention to provide a gaze-fixing device for an ophthalmologic microscope that keeps the patient's focus approximately 18°-20° offset from the illumination source.
It is a further object of the present invention to provide such a gaze-fixing device that can be attached to a conventional ophthalmologic microscope.
It is yet a further object of the present invention to provide a secondary gaze-fixing device to aid the ophthalmologist in making incisions on other parts of the eye.
SUMMARY OF THE INVENTION
In keeping with the above-identified objects, the present invention is a focus light for an ophthalmologic microscope. The focus light acts as a gaze-fixing device, which attaches to most conventional ophthalmologic microscopes.
According to one aspect of the invention, the focus light is mounted on an assembly, which fastens to the objective lens of the microscope. The illuminating light source is still passed through the objective lens, but the patient is directed to focus on the focus light. The focus light is a low luminescence light offset from the optical axis of the microscope by approximately 18° and is preferably red in color. The result is that a significant portion of the illuminating light source avoids the macula and preferably hits the optic nerve where it does not damage photoreceptors, and may cause less photophobia for the patient.
According to another aspect of the invention, secondary focus lights of an alternate color are added to the assembly. When an incision needs to be made in the lower (or even upper) portion of the eye, the patient is directed to temporarily focus on the secondary focus light.
According to yet another aspect of the present invention, two secondary focus lights are used. One is located on either side of the primary focus light on the assembly. Thus, the same assembly can be used by either a left-handed or right-handed ophthalmologist.
REFERENCES:
patent: 5155509 (1992-10-01), Kleinberg
Blumenfeld Kaplan & Sandweiss, P.C.
Manuel George
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