The present invention relates generally to instruments used in ophthalmic surgery and, more particularly, to instruments used to mark the cornea prior to the implantation and alignment of an intraocular lens (IOL).
Replacement of a cataract with an artificial IOL is now a well-accepted surgical procedure. Typically, during such a procedure the diseased lens is removed from the capsular bag by phacoemulsification and a replacement lens is folded, inserted into the capsular bag and allowed to unfold to act as a replacement lens.
Early implantable IOLs did not afford any correction for corneal astigmatism and a patient suffering from such a condition would still have to wear glasses even after the cataract is removed and a new lens inserted in its place.
Alcon Industries has developed its AcrySof® toric IOL which combines the flexibility of an implantable IOL with the astigmatic corrections available in typical glass or plastic eyeglass lenses. In order to use a toric IOL effectively, the lens must be rotated in the capsular bag to align the lens with a pre-calculated optimal axis, typically the steepest curvature of the cornea. To do so, a keratometer is used to measure the patient's cornea and to determine the steep axis of the cornea. When the toric IOL is implanted, a pair of reference marks on the toric IOL are aligned with the steep axis to provide the desired vision correction.
It is important to have an accurate measurement of the corneal curvature and equally important to find a method for identifying the steep axis during surgery so the IOL can be aligned properly.
The present invention relates to instruments which are used to mark the cornea of the patient to identify pre-phacoemulsification reference points to determine the orientation of the steep axis of the cornea so that after phacoemulsification the IOL can be rotated to align it properly with the steep axis.
To do so, the present invention provides a corneal marker having a marking ring with a front surface and an opposed rear surface. The marking ring is rotatably held in a yoke attached to an instrument handle and the ring is free to rotate 360° within the yoke.
Prior to phacoemulsification the patient's eye is examined and a keratometer is used to determine the angle of the steepest, or “steep” axis along which the astigmatism is most pronounced. The angle is then noted.
A series of four marking tabs are formed on the front surface of the ring placed at 90° degree intervals around the surface of the circular ring. After the marking tabs are coated with dye, one marking tab is aligned with the limbus of the eye and the instrument is then pressed against the cornea to leave marks corresponding to the 3, 6, 9 and 12 numerals on a clock face.
A keratometer is then placed on the eye with the 0° and 180° markings on the keratometer aligned with the marks left on the eye at the corresponding 0° and 180° degree locations. The ring is then rotated with respect to the yoke to allow the rear surface of the ring to come into contact with the cornea. The rear surface has a pair of axis marking tabs at the 0 and 180° positions on the ring.
The axis tabs are then coated with dye and the instrument is then moved to align the second surface with the cornea and to press the axis tabs against the cornea with the marking tabs aligned with the angle marking on the keratometer that corresponds to the steep axis on the cornea. The axis tabs make a pair of marks on the cornea, and it is this second set of reference marks that identifies the axis with which the IOL is aligned when it is inserted so that the stigmatic correction of the IOL is maximized.
The ability of the ring to rotate within the yoke makes it possible for the surgeon to hold the instrument in a variety of hand positions and still place the marking ring against the surface of the cornea. For example, the surgeon may use a limbal, superior or inferior approach to place the instrument on the eye and may adjust the position of the ring to accommodate this preference. It is also possible to use the instrument on both the left and right eye with equal facility.
U.S. Pat. No. 4,739,761 teaches and describes a cornea marker that employs a rotating marker wheel to allow the cornea to be marked at selected locations.
It is an object of the present invention to provide instruments useful for marking the cornea for the insertion and alignment of a multifocal IOL while allowing the surgeon to double check the location of the corneal steep axis prior to insertion of the lens.
It is a further object of the present invention to provide marking rings on such instruments that are rotatably grasped within an instrument handle in order to provide a variety of angles at which the instrument may be held and still manipulated to properly mark the cornea.
These and further objects of the present invention will become more apparent upon considering the accompanying drawings in which:
Referring now to
A third marking tab 34 is formed integral with upper surface 18 and midway along blade 16 between first and second marking tabs 22, 24. Tab 34 has an upper marking edge 36. A fourth marking tab 38 having a lower marking edge 40 extends from lower surface 20 opposite third marking tab 34.
While the marking tabs 22, 24, 34 and 38 are shown in
Referring now to
Attached to fork 48 is a combined gauge and keratometer assembly 50. As best seen in
Gauge ring 52 has a central circular aperture 56 formed therethrough. An inner toroidal marker ring 58 is rotatably fitted to gauge ring 52 through aperture 56. Ring 58 has a first right circular segment 60 held rotatably within the gauge ring 52 with first segment 60 extending above upper gauge ring surface 54. A reference mark 62 is engraved on ring 58.
Referring now to
A keratometer ring 78 is attached to inner wall 80 of marker ring 58 by ring shaft 82. When axis marker 42 is placed on a patient's cornea, light from the operating microscope is directed through keratometer ring 78 and will highlight the general shape of any astigmatism in the cornea. This is not intended as a precise identification of the position of the “steep axis” of the cornea, but is intended to provide a backup indicator to confirm to the surgeon that the previously obtained keratometer readings were correct in identifying the steep axis.
In use, marking tabs 74, 76 are coated with a suitable dye and marker ring 58 is rotated to bring reference mark 62 in alignment with the scale scribed on surface 54 to coincide with the angle of the previously-measured steep axis. Non-rotating markers 70, 72 are then coated with a suitable dye. The instrument is then placed on the eye to bring one of the non-rotating tabs 70, 72 at the corner of the eye such that tabs 74, 76 are in alignment with the steep axis. Tabs 74, 76 are then pressed against the cornea to leave a pair of marks that allow the surgeon to align the IOL along the steep axis after insertion.
As shown in
Referring now to
Referring now to
Referring now to
Thus, reference markers 108, 110, 112 and 114 extend outward from outer wall 96 of ring 92 while axis markers 116, 118 extend inward from inner wall 98 of ring 92.
Referring now to
As seen in
As seen in
Referring now to
In use, while a patient is seated, marker tabs 120, 122, 124 and 126 of ring 92 are coated with a surgically-acceptable dye, such as gentian blue or gentian violet. Next one of the reference markers is aligned with the limbus of the eye and handle 86 of instrument 84 is held in a horizontal position. To assist in aligning the instrument horizontally a spirit level 146 is positioned in handle 86 and a laser-scribed line 148 is formed on spirit level 146 and handle 148 as a reference line for the bubble 150 at spirit level 146 as seen in
In a preferred embodiment spirit level 146 may be removed from handle 148 for cleaning and sterilization.
Referring again to
Once horizontal alignment has been achieved, reference markers 108, 110, 112 and 114 are pressed against corneal surface 144. As seen in
As described above, prior to surgery the patient's steep axis is measured. As seen in
To mark the axis or position of the steep axis, axis marker marker tabs 116, 118 are coated with a suitable coloring agent or dye and ring 92 is rotated with respect to yoke 90 to position marker tabs 116, 118 for contact with corneal surface 144.
As seen schematically in
When marker tabs 116, 118 are aligned with the steep axis, ring 92 is pressed against corneal surface 144 and, as seen in
Referring now to
The surgeon can double check the alignment of the IOL by observing if the IOL is lined up with the corneal steep axis as determined by the marks 164, 166.
While the foregoing describes a preferred embodiment or embodiments of the invention, it is to be understood that this description is made by example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates, and while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims, such language is intended to cover the structures described herein as performing the recited functions, and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures.