Purpose: To obtain analytical formulas for calculating the ocular rotation and the prismatic effect with a general lens, centered or decentered, with particular reference to thick spherotoric spectacle lenses.
Methods: Linear theory is used, using the symplectic properties of optical matrices, to derive the desired formulas.
Results: By applying the general formulas to particular cases, the corresponding formulas are obtained, sometimes recovering formulas already known. Two examples serve to illustrate the use of the formulas obtained and to compare the results they provide with the ones obtained by exact ray tracing.
Conclusions: The linear formulas derived allow to find, in a rather easy way, quite accurate values of the ocular rotation and the prismatic effect in the paraxial region.