Ac stands for what in Javal's Rule equations?

• A. Corneal astigmatism
• B. Anterior chamber depth
• C. Accommodation
• D. Axial length

Answer: (A)

In Javal's Rule, Ac represents the corneal astigmatism—the toricity produced by the anterior surface of the cornea that largely shapes how light is focused in the eye. The rule expresses total refractive astigmatism as a combination of this corneal component (often scaled) plus a fixed term that accounts for lenticular and posterior corneal contributions. Because Ac is specifically the corneal contribution, it is not related to anterior chamber depth, accommodation, or axial length, which are different ocular factors.