Recovery from blindness

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Recovery from blindness is the phenomenon of a blind person gaining the ability to see, usually as a result of medical treatment. As a thought experiment, the phenomenon is usually referred to as Molyneux's problem . It is often stated that the first published human case was reported in 1728 by the surgeon William Cheselden. However, there is no evidence that Cheselden's patient, Daniel Dolins, actually recovered any vision. [1] Patients who experience dramatic recovery from blindness experience significant to total visual agnosia  –serious confusion with their visual perception.

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As a thought experiment

The phenomenon has often been presented in empiricism as a thought experiment, in order to describe the knowledge gained from senses, and question the correlation between different senses.

John Locke, an 18th-century philosopher, speculated that if a blind person developed vision, he would not at first connect his idea of a shape with the sight of a shape. That is, if asked which was the cube and which was the sphere, he would not be able to do so, or even guess.

The question was originally posed to him by philosopher William Molyneux, whose wife was blind: [2]

Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal, and nighly of the same bigness, so as to tell, when he felt one and the other, which is the cube, which is the sphere. Suppose then the cube and the sphere placed on a table, and the blind man made to see: query, Whether by his sight, before he touched them, he could now distinguish and tell which is the globe, which the cube? To which the acute and judicious proposer answers: 'Not. For though he has obtained the experience of how a globe, and how a cube, affects his touch; yet he has not yet attained the experience, that what affects his touch so or so, must affect his sight so or so...'

In 1709, in A New Theory of Vision, George Berkeley also concluded that there was no necessary connection between a tactile world and a sight world—that a connection between them could be established only on the basis of experience. He speculated:

the objects to which he had hitherto used to apply the terms up and down, high and low, were such as only affected or were in some way perceived by touch; but the proper objects of vision make a new set of ideas, perfectly distinct and different from the former, and which can in no sort make themselves perceived by touch (sect. 95).

This thought experiment (it was a thought experiment at the time) outlines the debate between rationalism and empiricism; to what degree our knowledge of the world comes from reason or experience.

Early cases

There are many stories or anecdotes of the phenomenon, preceding the first documented case, including one from the year 1020, of a man of thirty operated upon in Arabia. [3]

Before the first known human cases, some tests were done rearing animals in darkness, to deny them vision for months or years, then discover what they see when given light. A. H. Reisen found severe behavioural losses in such experiments; but they might have been due to degeneration of the retina. [4]

The first known case of published recovery from blindness is often stated to be that described in a 1728 report of a blind 13-year-old boy operated by William Cheselden. [5] Cheselden presented the celebrated case of the boy of thirteen who was supposed to have gained his sight after couching of congenital cataracts. In 2021, the name of Cheselden's patient was reported for the first time: Daniel Dolins. [1] As it happens, philosopher George Berkeley knew the Dolins family, had numerous social links to Cheselden, including the poet Alexander Pope, and Princess Caroline, to whom Cheselden's patient was presented. [1] The report misspelled Cheselden's name, used language typical of Berkeley, and may even have been ghost-written by Berkeley. [1] Despite his youth, the boy encountered profound difficulties with the simplest visual perceptions. Described by "Chesselden":

When he first saw, he was so far from making any judgment of distances, that he thought all object whatever touched his eyes (as he expressed it) as what he felt did his skin, and thought no object so agreeable as those which were smooth and regular, though he could form no judgment of their shape, or guess what it was in any object that was pleasing to him: he knew not the shape of anything, nor any one thing from another, however different in shape or magnitude; but upon being told what things were, whose form he knew before from feeling, he would carefully observe, that he might know them again; [6]

Unfortunately, Dolins was never able to see well enough to read, and there is no evidence that the surgery improved Dolins' vision at any point prior to his death at age 30. [1] A total of 66 early cases of patients who underwent cataract operations were reviewed by Marius von Senden in his German 1932 book, which was later translated into English under the title Space and sight. [7] In this book, von Senden argues that shapes, sizes, lengths and distances are difficult for blind people to judge, including for a time after their operation.

Examples and case studies

Virgil

In his book, An Anthropologist On Mars (1995), neurologist Oliver Sacks recounts the story of Virgil, a man who saw very little until having cataract surgery at age 50. Virgil's subsequent behavior was that of a "mentally blind" person—someone who sees but cannot decipher what is out there; he would act as if he were still blind. Often confused, Virgil rapidly sank into depression. [8]

Sidney Bradford

In 1974, Richard Gregory described a patient, Sidney Bradford, a 52-year-old who gained vision from corneal grafts to both eyes. No experimental psychologist was informed of the case until after the corneal grafting took place. His operation was able to reveal idiosyncrasies of the human visual system. For example, not having grown up with vision, Bradford did not perceive the ambiguity of the Necker cube. Nor was he able to interpret the perspective of two-dimensional art.

Nevertheless, he could accurately judge the distance to objects in the same room, having been familiar with these distances before regaining sight by virtue of having walked them. In a similar analogy between vision and sightless (touch-only) experience, Bradford was able to visually read the time on the ward clock just after his operation. Before surgery Bradford was a machinist, but even after acquiring vision preferred working with his eyes closed to identify tools. He died two years after his operation due to a prolonged period of ill health, with no specific cause of death noted. [9] [10] [11]

Michael May

Michael G. "Mike" May (born 1954) was blinded by a chemical explosion at the age of 3 but regained partial vision in 2000, at 46, after corneal transplantation and a pioneering stem cell procedure by San Francisco ophthalmologist Daniel Goodman. [12] May had a stem-cell transplant in his right eye in 2001 when he was 47, after 40 years of blindness. He reportedly has adapted well to his recovered vision.

The effect of visual loss has an impact in the development of the visual cortex of the brain. The visual impairment causes the occipital lobe to lose its sensitivity in perceiving spatial processing. Sui and Morley (2008) proposed that after seven days of visual deprivation, a potential decrease in vision may occur. They also found an increasing visual impairment with deprivation after 30 days and 120 days. This study suggests that the function of the brain depends on visual input. May lost his eyesight at age three, when his vision was still not fully developed to distinguish shapes, drawings or images clearly. It would be difficult for him to be able to describe the world compared to a normal sighted person. For instance, May would have trouble differentiating complex shapes, dimension and orientations of objects. Hannan (2006) hypothesized that the temporal visual cortex uses prior memory and experiences to make sense of shapes, colours and forms. She proposed that the long-term effect of blindness in the visual cortex is the lack of recognition of spatial cues.

At three years of age, May's vision had still not reached the acuity of an adult person, so his brain was still not completely exposed to all possible clarity of images and light of the environment. This made it difficult for Michael to lead a normal daily life. Cohen et al. (1997) suggested that early blindness causes a poor development of the visual cortex with the result of a decrease in somatosensory development. This study proposed that Michael's long-term blindness affects his ability to distinguish in between faces of males and females, and to recognize pictures and images. In spite of the surgery on his right eye, his newly regained vision, after blindness of forty years, is not fully recovered. Thinus-Blanc and Gaunet (1997) suggest that early blinded people show limited ability in spatial representation. Michael still struggles to identify pictures or illustrations. The impairment of his visual cortex, due to the loss of his vision at a very early age, resulted in visual cortex cells that are not used to the stimuli in his surroundings. Cohen et al. (1997) proposed that in their early age, blinded subjects developed strong motivations to tactile discrimination tasks. May's early blindness benefited him so far; he developed very precise senses of hearing and touch.

In 2006, journalist Robert Kurson wrote a book on May, Crashing Through, expanded from an article he did for Esquire, [13] which was adapted into a motion picture. [14] Crashing Through was released on May 15, 2007.

Shirl Jennings

Shirl Jennings (1940–2003) was blinded by illness as a young boy. Experimental surgery in 1991 partially restored his vision, but like Bradford and May, Jennings found the transition to sightedness difficult. In 1992, a pneumonia infection resulted in anoxia, and ultimately cost Jennings his vision again.

Shander Herian

In 2011, The Guardian published a story about Shander Herian, who was blinded by illness at the age of 14 and fully recovered after an experimental surgery in middle age. [15]

Modern history

More recently, another condition called aniridia has been treated with reconstructive surgery using the membrane from the amniotic sac that surrounds a fetus combined with stem cell transplantation into the eye. [16] In 2003, three people were successfully implanted with a permanent "retinal prosthesis" by researchers at the University of Southern California. Each patient wore spectacles with miniature video cameras that transmitted signals to a 4-mm-by-5-mm retinal implant via a wireless receiver embedded behind the ear. [17]

See also

Notes

  1. 1 2 3 4 5 Leffler, CT; Schwartz, SG (February 2021). "The First Cataract Surgeons in the British Isles". American Journal of Ophthalmology. 230: 75–122. doi:10.1016/j.ajo.2021.03.009. PMC   8446104 . PMID   33744237.
  2. ↑ "The New Yorker: From the Archives: Content". The New Yorker . Archived from the original on 2006-08-31. Retrieved 2010-05-04. The seventeenth-century philosopher William Molyneux, whose wife was blind, posed the following question to his friend John Locke: "Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere [be] made to see: [could he now] by his sight, before he touched them . . . distinguish and tell which was the globe and which the cube?"
  3. ↑ "Recovery from Early Blindness" . Retrieved 2010-05-04.
  4. ↑ "recovery from blindness: Information from Answers.com". Answers.com . Retrieved 2010-05-04.
  5. ↑ "The New Yorker: From the Archives: Content". The New Yorker . Archived from the original on 2006-08-31. Retrieved 2010-05-04.
  6. ↑ An Account of Some Observations Made by a Young Gentleman, Who Was Born Blind, or Lost His Sight so Early, That He Had no Remembrance of Ever Having Seen, and Was Couch'd between 13 and 14 Years of Age. By Will. Cheselden. Philosophical Transactions, Vol. 35. (1727–1728), pp. 447–450.
  7. ↑ von Senden, Marius (1960). Space and sight: the perception of space and shape in the congenitally blind before and after operation. Methuen & Co.
  8. 1 2 "10 Must-Read Oliver Sacks Books and Literary Works". 25 June 2019.
  9. ↑ Bellows, Alan (2009). Alien Hand Syndrome: And Other Too-Weird-Not-To-Be-True Stories . Workman Publishing. pp.  209–212. ISBN   9780761152255.
  10. ↑ Pendergrast, Mark (2004). Mirror, Mirror: A History Of The Human Love Affair With Reflection. Basic Books. p. 336. ISBN   9780465054718.
  11. ↑ "Case Study: SB - The Man Who Was Disappointed with What He Saw". Health Check. 2010-08-25. BBC World Service.
  12. ↑ http://www.goodmaneyecenter.com/gev-goodman.html Daniel Goodman
  13. ↑ "Entertainment News - Latest Celebrity News". Esquire.
  14. ↑ "Hollywood Reporter news on film about May".
  15. ↑ Shander Herian, Jenny Hulme "Experience: I first saw my wife 10 years after we married", guardian.co.uk, 19 February 2011
  16. ↑ Anon. "Wade cook's eye reconstruction by Dr. Ming Wang". ABC news. ABC. Archived from the original on 2021-12-18. Retrieved 27 August 2010.
  17. ↑ WIRED Staff. "Slideshow: Bionic Eyes Benefit the Blind". Wired. ISSN   1059-1028 . Retrieved 2023-08-11.

Related Research Articles

Blindsight is the ability of people who are cortically blind to respond to visual stimuli that they do not consciously see due to lesions in the primary visual cortex, also known as the striate cortex or Brodmann Area 17. The term was coined by Lawrence Weiskrantz and his colleagues in a paper published in a 1974 issue of Brain. A previous paper studying the discriminatory capacity of a cortically blind patient was published in Nature in 1973. The assumed existence of blindsight is controversial, with some arguing that it is merely degraded conscious vision.

<span class="mw-page-title-main">William Cheselden</span> English surgeon (1688–1752)

William Cheselden was an English surgeon and teacher of anatomy and surgery, who was influential in establishing surgery as a scientific medical profession. Via the medical missionary Benjamin Hobson, his work also helped revolutionize medical practices in China and Japan in the 19th century.

Astereognosis is the inability to identify an object by active touch of the hands without other sensory input, such as visual or sensory information. An individual with astereognosis is unable to identify objects by handling them, despite intact elementary tactile, proprioceptive, and thermal sensation. With the absence of vision, an individual with astereognosis is unable to identify what is placed in their hand based on cues such as texture, size, spatial properties, and temperature. As opposed to agnosia, when the object is observed visually, one should be able to successfully identify the object.

Michael G. May is an American business executive, skier and enthusiast of other sports who was blinded by a chemical explosion at the age of three, but regained partial vision in 2000, at the age of 46, after cornea transplants and a pioneering stem cell procedure by San Francisco ophthalmologist Daniel Goodman. In 1999, May founded the Sendero Group in Davis, California, United States, which employs many individuals who are blind or visually impaired. Sendero has assisted those with sight disabilities by producing the first accessible GPS solution for blind persons. The Sendero Group's GPS technology received the Consumer Electronics Show's "Innovation Honoree" title in 2004 and 2009.

<span class="mw-page-title-main">Cataract surgery</span> Removal of opacified lens from the eye

Cataract surgery, also called lens replacement surgery, is the removal of the natural lens of the eye that has developed a cataract, an opaque or cloudy area. The eye's natural lens is usually replaced with an artificial intraocular lens (IOL) implant.

Simultanagnosia is a rare neurological disorder characterized by the inability of an individual to visually perceive more than a single object at a time. This type of visual attention problem is one of three major components of Bálint's syndrome, an uncommon and incompletely understood variety of severe neuropsychological impairments involving space representation. The term "simultanagnosia" was first coined in 1924 by Wolpert to describe a condition where the affected individual could see individual details of a complex scene but failed to grasp the overall meaning of the image.

Sensory substitution is a change of the characteristics of one sensory modality into stimuli of another sensory modality.

<span class="mw-page-title-main">Visual impairment</span> Decreased ability to see

Visual or vision impairment is the partial or total inability of visual perception. In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. The terms low vision and blindness are often used for levels of impairment which are difficult or impossible to correct and significantly impact daily life. In addition to the various permanent conditions, fleeting temporary vision impairment, amaurosis fugax, may occur, and may indicate serious medical problems.

Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the brain's occipital cortex. Cortical blindness can be acquired or congenital, and may also be transient in certain instances. Acquired cortical blindness is most often caused by loss of blood flow to the occipital cortex from either unilateral or bilateral posterior cerebral artery blockage and by cardiac surgery. In most cases, the complete loss of vision is not permanent and the patient may recover some of their vision. Congenital cortical blindness is most often caused by perinatal ischemic stroke, encephalitis, and meningitis. Rarely, a patient with acquired cortical blindness may have little or no insight that they have lost vision, a phenomenon known as Anton–Babinski syndrome.

Visual agnosia is an impairment in recognition of visually presented objects. It is not due to a deficit in vision, language, memory, or intellect. While cortical blindness results from lesions to primary visual cortex, visual agnosia is often due to damage to more anterior cortex such as the posterior occipital and/or temporal lobe(s) in the brain.[2] There are two types of visual agnosia, apperceptive and associative.

Akinetopsia, also known as cerebral akinetopsia or motion blindness, is a term introduced by Semir Zeki to describe an extremely rare neuropsychological disorder, having only been documented in a handful of medical cases, in which a patient cannot perceive motion in their visual field, despite being able to see stationary objects without issue. The syndrome is the result of damage to visual area V5, whose cells are specialized to detect directional visual motion. There are varying degrees of akinetopsia: from seeing motion as frames of a cinema reel to an inability to discriminate any motion. There is currently no effective treatment or cure for akinetopsia.

<span class="mw-page-title-main">Molyneux's problem</span> Philosophical thought experiment

Molyneux's problem is a thought experiment in philosophy concerning immediate recovery from blindness. It was first formulated by William Molyneux, and notably referred to in John Locke's An Essay Concerning Human Understanding (1689). The problem can be stated in brief, "if a man born blind can feel the differences between shapes such as spheres and cubes, could he, if given the ability to see, distinguish those objects by sight alone, in reference to the tactile schemata he already possessed?"

Tactile discrimination is the ability to differentiate information through the sense of touch. The somatosensory system is the nervous system pathway that is responsible for this essential survival ability used in adaptation. There are various types of tactile discrimination. One of the most well known and most researched is two-point discrimination, the ability to differentiate between two different tactile stimuli which are relatively close together. Other types of discrimination like graphesthesia and spatial discrimination also exist but are not as extensively researched. Tactile discrimination is something that can be stronger or weaker in different people and two major conditions, chronic pain and blindness, can affect it greatly. Blindness increases tactile discrimination abilities which is extremely helpful for tasks like reading braille. In contrast, chronic pain conditions, like arthritis, decrease a person's tactile discrimination. One other major application of tactile discrimination is in new prosthetics and robotics which attempt to mimic the abilities of the human hand. In this case tactile sensors function similarly to mechanoreceptors in a human hand to differentiate tactile stimuli.

Apperceptive agnosia is a neurological disorder characterized by failures in recognition due to a failure of perception. In contrast, associative agnosia is a type of agnosia where perception occurs but recognition still does not occur. When referring to apperceptive agnosia, visual and object agnosia are most commonly discussed; this occurs because apperceptive agnosia is most likely to present visual impairments. However, in addition to visual apperceptive agnosia there are also cases of apperceptive agnosia in other sensory areas.

Visual perception is the ability to interpret the surrounding environment through photopic vision, color vision, scotopic vision, and mesopic vision, using light in the visible spectrum reflected by objects in the environment. This is different from visual acuity, which refers to how clearly a person sees. A person can have problems with visual perceptual processing even if they have 20/20 vision.

Anton syndrome, also known as Anton-Babinski syndrome and visual anosognosia, is a rare symptom of brain damage occurring in the occipital lobe. Those who have it are cortically blind, but affirm, often quite adamantly and in the face of clear evidence of their blindness, that they are capable of seeing. Failing to accept being blind, people with Anton syndrome dismiss evidence of their condition and employ confabulation to fill in the missing sensory input. It is named after the neurologist Gabriel Anton. Only 28 cases have been published.

Blind artists are people who are physically unable to see normally, yet work in the visual arts. This seeming contradiction is overcome when one understands that only around 10% of all people with blindness can see absolutely nothing at all. As such most blind people can in fact perceive some level of light and form, and it is by applying this limited vision that many blind artists create intelligible art. Also, a blind person may once have been fully sighted and yet simply lost part of their vision through injury or illness. Blind artists are able to offer insight into the study of blindness and the ways in which art can be perceived by the blind, in order to better improve art education for the visually impaired.

Form perception is the recognition of visual elements of objects, specifically those to do with shapes, patterns and previously identified important characteristics. An object is perceived by the retina as a two-dimensional image, but the image can vary for the same object in terms of the context with which it is viewed, the apparent size of the object, the angle from which it is viewed, how illuminated it is, as well as where it resides in the field of vision. Despite the fact that each instance of observing an object leads to a unique retinal response pattern, the visual processing in the brain is capable of recognizing these experiences as analogous, allowing invariant object recognition. Visual processing occurs in a hierarchy with the lowest levels recognizing lines and contours, and slightly higher levels performing tasks such as completing boundaries and recognizing contour combinations. The highest levels integrate the perceived information to recognize an entire object. Essentially object recognition is the ability to assign labels to objects in order to categorize and identify them, thus distinguishing one object from another. During visual processing information is not created, but rather reformatted in a way that draws out the most detailed information of the stimulus.

<span class="mw-page-title-main">Congenital cataract</span> Opacity in the eyes lens present at birth

Congenital cataracts are a lens opacity that is present at birth. Congenital cataracts occur in a broad range of severity. Some lens opacities do not progress and are visually insignificant, others can produce profound visual impairment.

Childhood cataract is cataract that occurs at birth or in childhood. It may be congenital or acquired.

References

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