Corneal young's modulus algorithm and system using the same
A corneal young's modulus algorithm and system using the same is provided, comprising a tonometer and a computation unit. The computation unit comprises an algorithm for calculating young's modulus. The algorithm comprises: (S 1 ) read at least one parameter measured by a tonometer; (S 2 ) apply the at least one parameter and an initial value of Young's modulus to a first equation to obtain an inner deformation amount and an outer deformation amount; (S 3 ) apply the inner deformation amount and the outer deformation amount to a second equation to obtain a calculated deformation amount; (S 4 ) determine if an error value between the calculated deformation amount and the actual deformation amount is minimal; and (S 5 ) obtain Young's modulus.
1. A corneal stiffness testing method, comprising the following steps:
(S 1 ) read parameters of a corneal through a tonometer, wherein the tonometer snaps corneal sectional images and acquires parameters from the images, and the parameters include dented edge angle α, corneal radius R, corneal thickness t, intraocular pressure p, and corneal vertical deformation D t of the corneal;
(S 2 ) apply the parameters and an initial value of Young's modulus to a first equation:
[
{
1
2
+
2
λ
(
1
-
v
)
(
1
-
cos
α
)
sin
α
}
-
1
2
-
1
2
{
3
2
+
2
λ
1
-
v
cot
α
}
]
{
w
i
_
w
o
_
}
=
{
-
α
λ
+
λcotα
10
[
α
2
λ
2
+
1
2
(
w
o
_
-
w
i
_
)
2
]
α
λ
-
λcotα
10
[
α
2
λ
2
+
1
2
(
w
o
_
-
w
i
_
)
2
]
+
t
λ
c
cos
2
α
sin
α
p
_
}
wherein
p
_
=
pR
2
Et
2
,
E is the Young's modulus, v is the Poisson ratio, and obtaining an inner deformation amount W i , and an outer deformation amount W o );
(S 3 ) apply the inner deformation amount W i and the outer deformation amount W o to a second equation:
Δ
R
≡
(
2
+
w
i
_
-
w
o
_
)
(
1
-
cos
α
)
-
λ
4
2
w
o
_
2
and obtain a calculated deformation amount Δ;
(S 4 ) determine if an error value between the calculated deformation amount Δ and the actual deformation amount D t is less than or equal to a given minimal value;
(S 5 ) obtain Young's modulus of the corneal through
p
_
=
pR
2
Et
2
;
and
(S 6 ) determine if the corneal has glaucoma symptoms, myopia, or the requirement to wear Orthokeratology lens with the Young's modulus.
2. The corneal stiffness testing method as claimed in claim 1 , wherein if the error value determined by Step (S 4 ) is not less than or equal to the given minimal value, return to Step (S 2 ) and follow an optimized procedure to calculate the error value iteratively until the error value is less than the given minimum value.
3. The corneal stiffness testing method as claimed in claim 1 , wherein the error value is equal to the given minimal value when the error value is 0 or approached to 0.
4. A corneal stiffness testing system, comprising:
a tonometer, directing an external force to an eye to detect parameters of corneal of the eye; and
a computation unit, computes Young's modulus of the corneal with the parameters, computation unit uses following steps:
(S 1 ) read parameters of a corneal through a tonometer, wherein the tonometer snaps corneal sectional images and acquires parameters from the images, and the parameters include dented edge angle α, corneal radius R, corneal thickness t, intraocular pressure p, and corneal vertical deformation D t of the corneal;
(S 2 ) apply the parameters and an initial value of Young's modulus to a first equation:
[
{
1
2
+
2
λ
(
1
-
v
)
(
1
-
cos
α
)
sin
α
}
-
1
2
-
1
2
{
3
2
+
2
λ
1
-
v
cot
α
}
]
{
w
i
_
w
o
_
}
=
{
-
α
λ
+
λcotα
10
[
α
2
λ
2
+
1
2
(
w
o
_
-
w
i
_
)
2
]
α
λ
-
λcotα
10
[
α
2
λ
2
+
1
2
(
w
o
_
-
w
i
_
)
2
]
+
t
λ
c
cos
2
α
sin
α
p
_
}
wherein
p
_
=
pR
2
Et
2
,
is the Young's modulus, v is the Poisson ratio, and obtaining an inner deformation amount W i and an outer deformation amount W o ;
(S 3 ) apply the inner deformation amount IV, and the outer deformation amount w, to a second equation:
Δ
R
≡
(
2
+
w
i
_
-
w
o
_
)
(
1
-
cos
α
)
-
λ
4
2
w
o
_
2
and obtain a calculated deformation amount Δ;
(S 4 ) determine if an error value between the calculated deformation amount A and the actual deformation amount D t is less than or equal to a given minimal value;:
(S 5 ) obtain Young's modulus of the corneal through
p
_
=
pR
2
Et
2
;
and
(S 6 ) determine if the corneal has glaucoma symptoms, myopia, or the requirement to wear Orthokeratology lens with the Young's modulus.
5. The corneal stiffness testing system as claimed in claim 4 , wherein if the error value determined by Step (S 4 ) is not less than or equal to the given minimal value, return to Step (S 2 ) and follow an optimized procedure to calculate the error value iteratively until the error value is less than the given minimum value.