In the case of macropsia, the greater density of photoreceptor cells leads to greater stimulation making the object seem larger. In some cases, the effects of macropsia have been shown to be field dependent, in that the degree of visual distortion is related to the visual field angle. Non-uniform stretching or compression of the receptor distribution could explain the field dependency of the macropsia. If the compression forces were closer to the fovea the resulting compression would cause a greater amount of macropsia at lower field angles with little effect at higher field angles where the receptor distribution is not as compressed. Alterations in receptor 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.
In primary occlusal trauma, the cause of the mobility was the excessive force being applied to a tooth with a normal attachment apparatus, otherwise known as a periodontally-uninvolved tooth. The approach should be to eliminate the cause of the pain and mobility by determining the causes and removing them; the mobile tooth or teeth will soon cease exhibiting mobility. This could involve removing a high spot on a recently restored tooth, or even a high spot on a non-recently restored tooth that perhaps moved into hyperocclusion. It could also involve altering ones parafunctional habits, such as refraining from chewing on pens or biting ones fingernails. For a bruxer, treatment of the patients primary occlusal trauma could involve selective grinding of certain interarch tooth contacts or perhaps employing a nightguard to protect the teeth from the greater than normal occlusal forces of the patients parafunctional habit. For someone who is missing enough teeth in non-strategic positions so that the remaining teeth are forced to endure a greater per square inch occlusal force, treatment might include restoration with either a removable prosthesis or implant-supported crown or bridge. In secondary occlusal trauma, simply removing the "high spots" or selective grinding of the teeth will not eliminate the problem, because the teeth are already periodontally involved.