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Metamorphopsia (fromAncient Greek:μεταμορφοψία,metamorphopsia, 'seeing mutated shapes') is a type of distorted vision in which a grid of straight lines appears wavy or partially blank. In addition, metamorphopsia can result in misperceptions of an object's size, shape,[3] or distance to the viewer. People can first notice they suffer from the condition when looking atmini blinds in their home.[citation needed]
Initially characterized in the 1800s, metamorphopsia was described as one of the primary and most notable indications ofmyopic and senilemaculopathies.[4] Metamorphopsia can present itself as unbalanced vision, resulting from small unintentional movements of the eye as it tries to stabilize the field of vision.[4]
It is mainly associated withmacular degeneration, particularlyage-related macular degeneration withchoroidalneovascularization.[5] Other conditions that can present with complaints of metamorphopsia include: pathologicalmyopia,presumed ocular histoplasmosis syndrome, choroidal rupture and multifocalchoroiditis.[5]
The mechanisms that result in the development of metamorphopsia involve structural changes in theretina of the eye (retinal mechanism) as well as processing changes in thecerebral cortex of the brain (cortical mechanism).[6] The retinal mechanism involves the displacement of retinal layers which results in the mislocation of light on the retina.[6] The cortical mechanism, which was discovered after the retinal mechanism, is affected by perceptualfilling-in andvisual crowding effects.[6] The cortical mechanism was found to work in combination with the retinal mechanism to contribute to metamorphopsia in long-standingmaculopathy or after the treatment of macular disorders.[4]
Metamorphopsia can be a symptom of a number of eye disorders involving the retina or macula.[7] Some of these conditions include the following:
Tests used for diagnosis of metamorphopsia mostly make use ofsubjective assessments of how a person views regular patterns. Many of these tests have a poor ability to accurately diagnose or identify a person with the disease (i.e.,poor sensitivity).[8] The use of tests such as thepreferential hyperacuity perimetry, apsychophysical test that assesses misalignments of visual objects, may permit a more sensitive diagnosis of metamorphopsia.[8]
Metamorphopsia is a symptom of several common retinal and macular diseases, therefore treating the underlying disorder can improve symptoms. For people who have conditions such asepiretinal membrane (ERM),macular holes andretinal detachment, decreased metamorphopsia is associated with an increase invisual acuity.[4]Quantitative evaluation of metamorphopsia is an important step in understanding visual functions of individuals with macular disorders and is an essential tool for physicians in evaluating treatment results.[4]
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