Metamorphopsia

Metamorphopsia is a type of distorted vision in which a grid of straight lines appears wavy and parts of the grid may appear blank. People can first notice they suffer with the condition when looking at mini-blinds in their home. For example, straight lines might be wavy or bendy. Things may appear closer or further than they are.

The Amsler Grid showing the visual perception of the left eye of a person experiencing metamorphopsia (straight lines appear bent or curved)[1][2]

Initially characterized in the 1800s, metamorphopsia was described as one of the primary and most notable indications of myopic and senile maculopathies.[3] Metamorphopsia can present itself as unbalanced vision, resulting from small unintentional movements of the eye as it tries to stabilize the field of vision.[3] Metamorphopsia can also lead to the misrepresentation of an object’s size or shape.[4]

It is mainly associated with macular degeneration, particularly age-related macular degeneration with choroidal neovascularization.[5] Other conditions that can present with complaints of metamorphopsia include: pathological myopia, presumed ocular histoplasmosis syndrome, choroidal rupture and multifocal choroiditis.[5]

Pathology

The mechanisms that result in the development of metamorphopsia involve structural changes in the retina of the eye (retinal mechanism) as well as processing changes in the cerebral 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 perceptual “filling-in” and visual crowding effects.[6] The cortical mechanism was found to work in combination with the retinal mechanism to contribute to metamorphopsia in long-standing maculopathy or after the treatment of macular disorders.[3]

Causes of Metamorphopsia

Metamorphopsia can be a symptom of a number of eye disorders involving the retina or macula.[7] Some of these conditions include the following:

Diagnosis

Tests used for diagnosis of Metamorphopsia mostly make use of subjective 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 assessments such as a psychophysical test called preferential hyperacuity perimetry, which assesses a person’s ability to any misalignments of visual objects, may permit a more sensitive diagnosis of Metamorphopsia.[8]

Treatment and Prognosis

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 as Epiretinal membrane (ERM), Macular Holes and Retinal Detachment, decreased metamorphopsia is associated with an increase in visual acuity.[3] 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.[3]

Types

Dry (non-exudative, > 80%)—deposition of yellowish extracellular material in and between Bruch's membrane and retinal pigment epithelium (“drusen”) with gradual loss in vision.

Wet (exudative, 10–15%)—rapid loss of vision due to bleeding secondary to choroidal neovascularization.

Etymology

Gk, meta + morphe, form, opsis, sight

See also

References
  1. Retina. Ryan, Stephen J., 1940-2013. (5th ed.). [London?]: Saunders. 2013. p. 309. ISBN 978-1-4557-3780-2. OCLC 820879155.{{cite book}}: CS1 maint: others (link)
  2. Liu, Grant T. (23 January 2018). Liu, Volpe, and Galetta's neuro-ophthalmology : diagnosis and management. Volpe, Nicholas J.,, Galetta, Steven,, Preceded by: Liu, Grant T. (Third ed.). [Philadelphia]. pp. 60, 957. ISBN 978-0-323-34045-8. OCLC 1022795077.
  3. Midena, Edoardo; Vujosevic, Stela (2016). "Metamorphopsia: An Overlooked Visual Symptom". Ophthalmic Research. 55 (1): 26–36. doi:10.1159/000441033. ISSN 0030-3747. PMID 26554918. S2CID 8376773.
  4. River, Yaron; Ben Hur, Tamir; Steiner, Israel (1998-10-01). "Reversal of Vision Metamorphopsia: Clinical and Anatomical Characteristics". Archives of Neurology. 55 (10): 1362–8. doi:10.1001/archneur.55.10.1362. ISSN 0003-9942. PMID 9779666.
  5. Page 45 in: Hartnett, Mary; Steidl, Scott (2003). Clinical pathways in vitreoretinal disease. Stuttgart: Thieme. ISBN 1-58890-119-X.
  6. Chen, Qi; Liu, Zao-xia (2019-05-23). "Idiopathic Macular Hole: A Comprehensive Review of Its Pathogenesis and of Advanced Studies on Metamorphopsia". Journal of Ophthalmology. 2019: 1–8. doi:10.1155/2019/7294952. PMC 6556255. PMID 31240135.
  7. "Retina Summary Benchmarks - 2019". American Academy of Ophthalmology. 2017-11-01. Retrieved 2020-12-07.
  8. Simunovic, Matthew P. (July 2015). "Metamorphopsia and ITS Quantification". Retina. 35 (7): 1285–1291. doi:10.1097/IAE.0000000000000581. ISSN 0275-004X. PMID 26049620. S2CID 46100253.
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