Tomey UD-800 Instruction Manual page 134

■ 4-8
4. Personal A-Constant
A = P + AREF･RF + 2.5L + 0.9K - COR
Where:
AREF: Eye refractive power after surgery (D)
RF : Refractive factor
P > 16 → RF = 1.25
P≦ 16 → RF = 1
COR : Correction value
L < 20.0
20.0≦ L < 21.0
21.0≦ L < 22.0
22.0≦ L < 24.5
24.5≦ L
→ COR = 3
→ COR = 2
→ COR = 1
→ COR = 0
→ COR = -0.5