Optical characteristics of contact lens
1. Thick Lens Optics
F = F1 + F2-(t / n) F1F2
The key refractive power of a contact lens depends on FOZR(front optical zone radius of curvature).
2. Vertex distance effect
F = Fs / (1-dFs)
s = spectacle diopter
3. Tear lens
LL = BC-K
LL = tear lens
BC = Base Curve
K = corneal front surface curvature
4. ORv + CLP + LL = SRv
5. Magnification vs. spectacle
Think magnification change of myopia and hyperopia with contact lens?
6. Accommodation and convergence
Minus lens more than spectacle
Positive lens less than spectacle
A=1/s(1-2dP)
7. Others factors: temperature, moisture content, bending