The present invention utilizes spatially modulated optical force microscopy (SMOFM) with single beam optical force probing capability or with a holographic optical trapping system capable of multi-beam optical force probing coupled to a microscope objective, to generate a probe beam(s) as a force probe to perturb the object that is adhered or resting on a surface, so that deformations of the object may subsequently be quantified. This quantification is performed by imaging a sequence of four phase shifted replicas of the image using a computer-controlled spatial light modulator, and calculating the pixel by pixel optical path-length using existing algorithms. The change in optical path lengths, and consequently the viscoelastic or elastic response elicited, is an indication of damage or disease when the objects are cells. In another embodiment, the optical deformability of the cells may be measured and correlated with measurements of cytoskeletal/structural protein expression.