distribution can be the result of epiretinal membrane, neuroretina detachment and/or re-attachment, or retinoschisis. macropsia caused by surgical re-attachment of macula-off rhegmatogenous retinal detachment is not symmetrical around the fovea, resulting in differences size changes in the horizontal and vertical meridians. asymmetry has also been observed with retinoschisis, in which macropsia generally results in the vertical direction while micropsia presents in the horizontal direction. diagnosis macropsia is generally diagnosed once a patient complains of the characteristic symptoms, such as disproportionally large objects in their visual field. the amsler grid test can be used to diagnose macropsia, along with other visual maladies depending on the subjective disturbance reported by the patient after looking at the amsler grid. outward bulging of the lines on an amsler grid is consistent with patients experiencing macropsisa. the new aniseikonia test (nat) can quantify the degree of macropsia or micropsia independently in the vertical and horizontal meridians. the test consists of red and green semicircles on a black background with a white round fixation target. the size of the red semicircle is held constant while the green semicircle is varied in size in 1% increments. the patient wears a pair of red/green goggles so that one eye is tested at a time, and the patient attempts to determine when the semicircles are the same size. this is termed the reversal threshold and the size difference between the semicircles is reported as the degree of aniseikonia. a positive value indicates that the object was perceived bigger and thus corresponds to macropsia, and conversely a negative value indicates micropsia. the aniseikonia inspector contains an aniseikonia test based on the same principles as the nat, but the test is run on a computer screen, it is based on a forced choice method, and it can measure the size difference as a function of the size of the objects. the functionality of being able to measure the size difference as function of the size (i.e. field dependent testing) is especially important when the macropsia (or micropsia) has a retinal origin. treatment the most common way to treat forms of aniseikonia, including macropsia, is through the use of auxiliary optics to correct for the magnification properties of the eyes. this method includes changing the shape of spectacle lenses, changing the vertex distances with contact lenses, creating a weak telescope system with contact lenses and spectacles, and changing the power of one of the spectacle lenses. computer software, such as the aniseikonia inspector, has been developed to determine the prescription needed to correct for a certain degree of aniseikonia. the problem with correction through optical means is that the optics do not vary with field angle and thus cannot compensate for non-uniform macropsia. patients have reported significantly improved visual comfort associated with a correction of 5-10% of the aniseikonia. with regard to drug-induced or virus-induced macropsia, once the underlying problem, either drug abuse or viral infection, is treated, the induced macropsia ceases. research future research may focus on ways to limit the occurrence of retinally-induced macropsia due to surgery. in terms of treatment, the most effective optical correction is still being researched with respect to visual field angles and direction to a target. the susceptibility of certain age demographics to macropsia is a subject that requires further validation. overall, there have not been very many reports of macropsia induced by certain drugs, specifically zolpidem and citalopram. once a larger effort is made to compile such reports, there will inevitably be more research on the subject of macropsia.