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Alice in Wonderland Syndrome
Published in Alexander R. Toftness, Incredible Consequences of Brain Injury, 2023
Even though many different experiences are possible in Alice in Wonderland syndrome, there are some patterns to the specific distortions. Two of the most common visual distortions of this syndrome are distorting objects as being larger than normal and distorting them as being smaller than normal, which are respectively called macropsia and micropsia (Blom, 2016). For example, a person with Alice in Wonderland syndrome might perceive a horse to be the size of a cat, or a cat to be the size of a horse. Another common visual distortion is teleopsia, in which objects appear further away than they actually are, and this can occur even with the person's own body parts. Less common is pelopsia, in which objects appear closer than they actually are.
Macular disorders
Published in Thomas H. Williamson, Vitreoretinal Disorders in Primary Care, 2017
The patient notices a blur of the vision, distortion and macropsia (increased image size) as the membrane contracts the retina centrally. The membrane is seen on biomicroscopy as a reflective sheet (cellophane) or as a thick opaque membrane. The retinal arcades may be tortuous. A pseudohole in the central membrane should be discriminated from a full-thickness hole in the retina (macular hole) by a negative Watzke–Allen test45,46 and by performing an OCT scan. Vitreomacular traction syndrome is often accompanied by ERM, indicated by the attachment of the ERM to the posterior hyaloid membrane. The membrane is usually associated with the presence of mild CMO on fundus fluorescein angiography (FFA). Cavities in the retina can be seen on OCT and are an indication of damage to the retina from the action of the ERM. Occasionally, an ERM is seen without separation of the vitreous (Figures 6.26 through 6.31).47
Case 43: Feels like the room is changing shape
Published in Barry Wright, Subodh Dave, Nisha Dogra, 100 Cases in Psychiatry, 2017
Barry Wright, Subodh Dave, Nisha Dogra
The distortions of the ambient sounds are illusions. They are distortions of real perceptions. They would only be hallucinations if they occurred in the absence of external stimuli and were perceived as a true perception in external space (i.e. not a thought or an imagined sound). Similarly macropsia describes the sensation that objects are larger (and the person smaller in relation) than normal. Micropsia is the reverse.
Posterior cortical atrophy: clinical, neuroimaging, and neuropathological features
Published in Expert Review of Neurotherapeutics, 2023
John Best, Marianne Chapleau, Gil D. Rabinovici
The defining feature of PCA is the progressive decline in visuospatial and visuoperceptual functions. Patients often have preserved insight into their deficits. Individuals frequently report a prior history of evaluations with optometrists and ophthalmologists to investigate their visual complaints. This can include frequent changes in eyeglasses or even surgical procedures such as cataract surgery, without any improvement in their symptoms. Both in driving and navigating around the home, there is difficulty in judging distances, reading signs, or locating items. There can also be difficulty with identifying objects (visual agnosia) or recognizing faces (prosopagnosia). Perception can also be frequently altered, with perception of objects being larger (macropsia) or smaller (micropsia) than they actually are, or incorrect perception of motion.
Prediction of Visual Prognosis after Epiretinal Membrane Surgery Using Regression Tree Analysis
Published in Seminars in Ophthalmology, 2021
Tatsuhiko Sato, Shunsuke Shibata, Reina Yamauchi-Mori, Ken Hayashi
There were some limitations to this study. First, there was a selection bias, which may account for the better preoperative BCVAs than those reported by most previous studies.2–5,8,10,11 Second, we did not investigate the association between metamorphopsia/macropsia and preoperative and intraoperative parameters. As mentioned earlier, recent studies have focused on specific OCT findings to investigate the association between them and visual prognosis (postoperative visual acuity); this prompted us to identify the most important determinant of visual prognosis among preoperative and intraoperative parameters. Thus, we focused on postoperative visual acuity as the objective variable, and did not evaluate metamorphopsia/macropsia in this study. However, these manifestations are also important factors that affect the quality of vision. Further studies are required to address this issue.
Aniseikonia and anisometropia: implications for suppression and amblyopia
Published in Clinical and Experimental Optometry, 2019
Jayshree South, Tina Gao, Andrew Collins, Jason Turuwhenua, Kenneth Robertson, Joanna Black
Changes in retinal receptor distribution from retinal asymmetry or pathology will cause the same physical size retinal image to be captured by a different number of photoreceptors, resulting in a change in the perceived image size and shape. This can occur in conditions such as epiretinal membranes, macular oedema, or axial myopia. Epiretinal membranes that cause macular contraction compress photoreceptors closer together, so that a retinal image with the same angular size now stimulates more photoreceptors, resulting in macropsia (image appears larger than normal).2014 Conversely, if the photoreceptors are stretched across a larger area such as in high axial myopia, central serous chorioretinopathy1992 or macular oedema, the same retinal image stimulates fewer photoreceptors, resulting in micropsia (image appears smaller than normal). Retinally induced aniseikonia can arise from both overall differences in image sizes between eyes and localised distortions in image shape, producing severe symptoms that are difficult to treat because the magnitude of aniseikonia varies across the visual field.2007 Even after appropriate surgery or treatment for the underlying conditions, photoreceptor spacing may not fully recover, leaving the patient with distorted vision.2014