GB2295320A

GB2295320A - Device to align head and eyes with an ophthalmic laser

Info

Publication number: GB2295320A
Application number: GB9423073A
Authority: GB
Inventors: Charles Ninian John Mcghee; Constantine Anastas
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-11-16
Filing date: 1994-11-16
Publication date: 1996-05-29
Also published as: GB9423073D0

Abstract

A fixed or demountabie alignment device in the form of two limbs (1,8), each with a moveable alignment bar (3, 10), which together form a collapsible structure (fig 1) suitable for attachment to ophthalmic surgical lasers to improve the accuracy of head eye and therefore cornea axis alignment with respect to any chosen axis of said surgical laser beam prior to treatment. By these means the device provides the facility to deliver asymmetric or astigmatic laser treatment more accurately with regard to the desired axis or zone of treatment upon the cornea. <IMAGE>

Description

DEVICE TO CORRECTLY ALIGN AXES OF THE HEAD AND EYES WITH REGARD TO AN OPHTHALMIC THERAPEUTIC ( SURGICAL ) LASER BEAM.

This invention relates to a device designed to align the head and eyes of patients with regard to a surgical laser beam as may be used in the correction of refractive errors of the eye and pathological conditions of the cornea.

During the last ten years surgical lasers, primarily of the excimer laser ( 193nm ) group, but including other lasers of differing wavelength, have been utilised to reshape the surface contour of the comea in the treatment of refractive errors of the eye and in the removal of pathological material from the cornea.In certain ocular conditions, such as the treatment of comeal astigmatism, the laser beam requires to be aligned with a pre-determined axis upon the comea between axes 0 - 1800 or in some axis conventions 0 - 360" A degree of head tilt by subjects in the X, Y or Z axes relative to the path of the laser beam may reduce the effectiveness of the laser ablation or cause misalignment of the laser beam axis and the desired axis upon the corneal surface.Presently there are no devices incorporated in, or that can be added to, ophthalmic (ocular) surgical lasers which will enable alignment of the most important Y and Z axes of the eyes and head of patients, such axes being defined with the patient lying flat in the recumbent position and viewed in profile. This inability to accurately align head, eyes and therefore corneal axes with the beam of surgical lasers can lead to suboptimal treatment of refractive disorders such as myopia, hypermetropia and particularly corneal astigmatism. Where a pathological process is limited to a discrete area of the cornea accurate alignment of the head and eyes might be equally important in the accurate application of ophthalmic surgical lasers.

According to the present invention two simple alignment devices are provided in a framework which can be permanently or temporarily attached to existing or future ophthalmic laser systems used in the treatment of comeal or refractive disorders. The device is constructed in the shape of an inverted "L" with vertical and horizontal limbs. The vertical limb contains a large rectangular aperture on the outside of which is mounted a vertically rectangular, transparent alignment device which exhibits 3 vertical lines which are parallel with the longitudinal axis of the laser beam being utilised.When the patient is recumbent these vertical lines will allow accurate alignment of the patient's head in the Y axis by movement of the head until appropriate anatomical landmarks - the inferior orbital rim and the upper external acoustic meatus - are vertically aligned as viewed against the vertical markings upon the transparent alignment component of the invention. The horizontal limb of the invention will be positioned over the patient's head and eyes. The horizontal limb also contains a large rectangular aperture over which is positioned a rectangular semi-silvered mirror which is moveable in the X axis and contains a horizontal, or horizon line (as viewed by the patient) in the Z axis.By illuminating the patient's face and viewing the eyes through the semisilvered mirror from above, an observer can, by moving the patient's head, objectively and accurately align both pupils with this line in the Z axis, and thereby align the eyes and head in this Z axis. Simultaneously, by observing the undersurface of this semisilvered mirror the patient can see a reflection of their own pupils and the line drawn upon the surface of the mirror in the "Z" axis, and by moving their head such that said line is noted to pass through the centre of each pupil as seen by reflection, the patient can subjectively confirm accurate ocular and head alignment in the Z axis.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1. Shows the instrument in perspective.

Figure 2. Shows the side view of the instrument.

Figure 3. Illustrates the plan view of the instrument.

Figure 4. Demonstrates the instrument in operating position relative to a subject. (Front view) Figure 5. Shows the instrument in operating position with patient axes and observer positions indicated ( Perspective view ) Referring to the drawings the device consists of a horizontal limb (8) hinged to a vertical limb (1) at right angles forming the shape of an inverted 'L' ( fig 1 ). The device can be releasably or permanently attached to the excimer laser or laser couch by, for example, bolts, catches or other means (6) which are not illustrated in detail. To align the patients head and eyes in the Y axis the reclining patient's head is viewed via the adjustable transparent bar (3) upon which vertical lines (4)( parallel with the longitudinal laser axis ) have been marked (Fig 2).

The patient's lower orbital rim and superior aspect of the external auditory meatus are aligned by the observer moving the head until these points align with one of these vertical lines (4)(Fig 5). To minimise unnecessary patient movement in the X axis during this part of the alignment procedure the transparent bar (3) has a limited degree of movement in the X axis as indicated by the arrow (it)( Fig 2 ).

Once alignment in the Y axis has been established as above, the patient's pupils are viewed by the observer looking through the semi-silvered transparent horizontal bar (10)( Fig 3 ) and the patient's head moved until both pupils are aligned with the line (11) representing correct alignment in the Z axis ( Fig 5 ). This alignment in the Z axis can be further confirmed subjectively by the patient examining the reflection of their own pupils relative to the line (1 l)( which should pass through the centre of each pupil reflection ) on the semi-mirrored horizontal bar (lO)( Fig 4 & Fig 5). When both objective and subjective alignments coincide the patients eyes should be correctly aligned in the Z axis and therefore the 1800 axis of each cornea should be correctly aligned with regard to the laser beam and it therefore follows that the other axes of the cornea will be appropriately aligned relative to the laser beam. The alignment device can be demounted or folded out of the path of the laser prior to treatment.

Claims

1. A fixed or demountable eye and head alignment device, in the form of two limbs forming an inverted 'L' each with a moveable alignment bar, to enable alignment of the head, eyes and corneal axes of a reclining patient in the Y and Z axes relative to an ophthalmic ( ocular ) surgical laser, the alignment bar on the vertical limb enabling accurate alignment of the head and eyes in the Y or longitudinal axis of the laser beam, the alignment bar on the horizontal limb enabling objective ( observer ) and subjective ( patient ) alignment of the patient's eyes and therefore corneal axes in the Z axis relative to an ophthalmic surgical laser, by such alignment this device will more accurately facilitate accurate orientation of the axis of an elliptical, oval or non-symmetric laser beam with any chosen axis upon the cornea.

2. An ophthalmic laser eye alignment device as claimed in 1 wherein a semi-silvered or semimirrored horizontal bar is provided to allow subjective alignment of the eyes by the patient in a chosen axis relative to an ophthalmic laser beam.

3. An ophthalmic laser eye alignment device as claimed in 1 & 2 wherein a transparent, semisilvered or semi-mirrored horizontal bar upon which markings are provided to enable the objective alignment of the eyes of a patient in a chosen axis relative to an ophthalmic laser beam.

4. An ophthalmic laser eye and head alignment device as claimed in any preceding claim, wherein a vertical alignment device is utilised to align the inferior orbital rim and the external acoustic meatus, and thereby the head and eyes with the longitudinal axis relative to an ophthalmic laser beam.

5. An ophthalmic laser alignment device as claimed in any preceding claim which will enable the accurate alignment of any chosen corneal axis with the corresponding laser beam axis.

6. An ophthalmic laser alignment device as claimed in any preceding claim which will improve the ophthalmic laser treatment of refractive disorders and corneal astigmatism by allowing accurate head and ocular alignment relative to an ophthalmic laser beam.

7. An ophthalmic laser alignment device as claimed in any preceding claim which can be temporarily or permanently attached to an ophthalmic laser device or associated couch or chair.

8. An ophthalmic laser alignment device as claimed in any preceding claim which can readily be demounted or folded out of the path of an ophthalmic laser beam prior to treatment.

9. An ophthalmic laser head and eye alignment device as claimed in any preceding claim which by improving the accuracy of head and eye axis alignment, prior to ocular laser surgery, will improve the outcome of laser treatment for astigmatic or asymmetric corneal disorders.

10. An ophthalmic laser alignment device substantially as described herein with reference to figures 1-5 of the accompanying drawings.