Systems and methods for laser correction of astigmatism incident with lens replacement surgery
A nomogram, a method for determining how to cut a cornea to produce a particular vision correction, and a system and method for determining how to make a vision correction when a precision cutting tool is being used as opposed to the performance of hand cuts. In a further embodiment, measurement of astigmatism to be corrected, calculation of the nomogram, and the actual cutting are mostly or completely automated eliminating human error from the system.
1. A method of cutting cornea of an eye to correct astigmatism, the method comprising:
providing a corneal topography system;
providing a computer communicably coupled to said corneal topography system;
determining an amount of astigmatism of said eye using said corneal topography system;
determining an axis of said astigmatism of said eye using said corneal topography system;
determining an age of said eye;
selecting a mirrored cut position in said cornea using said computer, said cut position being less than a 10 mm optical zone and greater than a 6 mm optical zone and comprising two cuts on opposing sides of said eye, said optical zones being measured radially from a pupillary center of said eye;
receiving said amount and said axis on said computer from said corneal topography system;
calculating an arcuate cut length from said amount and said age based on cut positions including:
determining, with said computer, that said axis is greater than 20° from vertical and horizontal axis of said eye; and
calculating, with said computer, the cut length using a first formula:
cut length=60°−(5°· X )+(5°· Y );
where
X
=
number
of
patient
'
s
age
in
years
-
30
20
;
and
Y
=
number
of
patient
'
s
astigmatism
in
diopters
-
2
0.2
;
or,
determining, with said computer, that said axis is less than or equal to 20° from vertical axis of said eye; and
calculating, with said computer, the cut length using a second formula:
cut length=65°−(5° · X )+(5° · Y );
where
X
=
number
of
patient
'
s
age
in
years
-
30
20
;
and
Y
=
number
of
patient
'
s
astigmatism
in
diopters
-
2
0.2
;
and
utilizing a femtosecond laser to cut said cut length at said cut position.
2. The method of claim 1 , wherein said cut position is greater than an 8 mm optical zone.
3. The method of claim 1 , wherein said cut position is at an optical zone being measured about 8 mm radially from the pupillary center of said eye.
4. The method of claim 1 , wherein said cut position is at an optical zone being measured about 9 mm radially from the pupillary center of said eye.
5. The method of claim 1 , wherein said cut position is at an optical zone being measured between 8 mm and 9 mm radially from the pupillary center of said eye.
6. The method of claim 1 , wherein said cut position is at an optical zone being measured between 9 mm and 10 mm radially from the pupillary center of said eye.
7. The method of claim 1 , wherein said cut length is between 15° and 90°.
8. A method of cutting cornea of an eye to correct astigmatism, the method comprising:
providing a corneal topography system;
providing a computer communicably coupled to said corneal topography system;
determining an amount of astigmatism of said eye using said corneal topography system;
determining an axis of said astigmatism of said eye using said corneal topography system;
determining an age of said eye;
selecting a cut position in said cornea using said computer;
receiving said amount and said axis on said computer from said corneal topography system;
calculating an arcuate cut length from said amount and said age based on cut positions including:
determining, with said computer, that said axis is greater than 20° from vertical and horizontal axis of said eye; and
calculating, with said computer, the cut length using a first formula:
cut length=60°−(5°− X )+(5°− Y );
where
X
=
number
of
patient
'
s
age
in
years
-
30
20
;
and
Y
=
number
of
patient
'
s
astigmatism
in
diopters
-
2
0.2
;
and
utilizing a femtosecond laser to cut said cut length at said cut position.
9. The method of claim 8 , wherein said cut is one of a pair of mirrored cuts on opposing sides of said eye.
10. The method of claim 8 , wherein said cut length is between 15° and 90°.
11. A method of cutting cornea of an eye to correct astigmatism, the method comprising:
providing a corneal topography system;
providing a computer communicably coupled to said corneal topography system;
determining an amount of astigmatism of said eye using said corneal topography system;
determining an axis of said astigmatism of said eye using said corneal topography system;
determining an age of said eye;
selecting a cut position in said cornea using said computer;
receiving said amount and said axis on said computer from said corneal topography system;
calculating an arcuate cut length from said amount and said age based on cut positions including:
determining, with said computer, that said axis is no more than 20° from vertical axis of said eye; and
calculating, with said computer, the cut length using a second formula:
cut length=65°−(5°− X )+(5°− Y );
where
X
=
number
of
patient
'
s
age
in
years
-
30
20
;
and
Y
=
number
of
patient
'
s
astigmatism
in
diopters
-
2
0.2
;
and
utilizing a femtosecond laser to cut said cut length at said cut position.
12. The method of claim 11 , wherein said cut is one of a pair of mirrored cuts on opposing sides of said eye.
13. The method of claim 11 , wherein said cut length is between 15° and 90°.