Tomey UD-800 Instruction Manual page 136

■ 4-10
r : Radius of corneal curvature (mm)
= {(KI – 1) × 1000}/K
KI : Cornea equivalent refractive index
P : Implanted IOL power (D)
V : Vertex distance (mm)
= 12
na : Aqueous humor and vitreous refractive index
= 1.336
nc : Corneal reflective index
= 1.333
4. Personal A-Constant

   2 
A b b
Where:
a : 0.62467 2 α
b : 0.62467 {2α (H – 72.083)} + β}
c : α (H – 72.083)
α : P (1 – nc) + 0.001P•AREF {V (nc – 1) – r}
β : P [na•r + L1 (nc – 1)
+ 0.001AREF {L1•r + V•L1 (1 – nc) - na•V•r }]
γ : na [1000X – P•L1•r + AREF
{0.001P•V•L1•r – (V•X + L1•r)}]
AREF : Refractive power of eye after surgery (D)

4 ac / 2 a
2
+ β (H-72.083) + γ