Eyes on Ice & No Blind Mice: Visions of Science from the Science of Vision

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A Decade of Change".

Journals of the Century. Retrieved 18 September Retrieved 30 September Retrieved 27 September Recent Advances in Ophthalmology, Volume Retrieved from " http: Navigation menu Personal tools Log in. Views Read View source View history. Navigation Main page Recent changes Random page Help.

This page was last edited on 29 September , at Privacy policy About Timelines Disclaimers Mobile view. The sclera and cornea were understood to form part of the outer layer of the eye, with the pupil and ocular fluid occupying the middle part. This fluid was thought to flow to the brain via a tube.

Aristotle introduced empiricism to these fancied structures by dissecting the eyes of animals, and he thus discovered three layers within the eye. Ophthalmologic progress slows during the Middle Ages. Roger Bacon, however, makes a notable contribution to ophthalmology with his work, Opus Majus.

This increased the level of precision that was possible in the diagnosis and treatment of ophthalmologic conditions. In particular, the operative treatment of glaucoma was refined at this time, and has helped greatly to improve patient outcomes.

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Several subspecialties were introduced to focus on particular areas or diseases of the eye. These include cataract, glaucoma, pediatrics, cornea and oncology subspecializations, among others.

In the Ebers Papyrus , a section is devoted to eye diseases. Indian surgeon Sushruta describes 76 ocular diseases, as well as several ophthalmological techniques and instruments. Sushruta is particularly interested in cataract surgery, and is referred to as the first cataract surgeon. Surgeons in ancient India already practice couching.

Greek philosopher Celsus draws the lens in the center of the eye. Greek physician Rufus of Ephesus puts forward the concept of a fourth layer, the epithelial layer that covers the eye. Rufus also notes that the eye has two chambers, one filled with water extending from the cornea to the lens, and one filled with viscous fluid occupying the space between the lens and the retina.

Arab polymath Ibn al-Haytham writes his Book of Optics. Arab Muslim ophthalmologist Ammar Al-Mawsili describes the suction of a cataract through the needle. Italian anatomist Hieronymus Fabricius illustrates the lens in its true anatomic position. French ophthalmologist Jacques Daviel publishes the first account of cataract extraction through an inferior corneal incision.

English surgeon Samuel Sharp successfully performs intracapsular cataract extraction.

Timeline of ophthalmology - Timelines

The first hospital dedicated to the practice of ophthalmics opens in London. Prussian ophthalmologist Albrecht von Graefe improves Jacques Daviel 's extracapsular cataract extraction technique using a superior corneal incision. English mathematician Charles Babbage invents the ophthalmoscope, which enables viewing of the interior of the eye. German physician Hermann von Helmholtz independently reinvents the ophthalmoscope. Dutch ophthalmologist Hermann Snellen develops his eponymous Snellen chart to measure visual acuity.

The chart would rapidly become a global standard. Archives of Ophthalmology and Otology is released. Tierney says studies of the Mexican cave fish suggest another form of natural selection could be at play. So-called pleiotropy involves one gene having more than one function. In the cave fish, for example, there's evidence that the same gene responsible for eye loss also increases the number of taste buds. More taste buds are great when you live in the dark and depend on picking up chemical signals from the environment, says Douglas Futuyma, professor of ecology and evolution at the State University of New York at Stony Brook.

It's just a more subtle expression of Darwin's idea of natural selection.

There is, however, also evidence for the operation of an evolutionary mechanism that doesn't involve natural selection, Tierney says. It's possible that the genes involved in cases of regressive evolution don't offer any advantage or disadvantage to the organism. Deleterious mutations in these genes would then have no impact on survival, and would not be affected by the pressures of natural selection. Over time, these mutated genes could become dominant — in short, eye loss could result as a by-product from the spread of faults in genes that no longer matter.

This 'neutral' theory of evolution caused a storm when it was first introduced decades ago, and arguments remain today over whether natural selection or neutral theory explains cases of regressive evolution.

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Tierney's own study of Western Australia's blind water beetles found evidence to support both natural selection and neutral theory. Comparing the gene expression in the blind beetles with their sighted above-ground cousins, Tierney and colleagues found the two underground species had no expression of the vision-related opsin gene that was still present in the seeing beetles.

This is clear evidence to support the neutral theory of evolution, says Tierney. In the absence of any advantage in being able to see, random deleterious mutations could have simply accumulated in the below-ground beetle's opsin gene, eventually affecting its function. In a third species, the opsin gene was only partly functional. If you favoured the neutral theory this could suggest that not enough time had passed for the gene to become completely faulty, says Tierney.

Blind People Regain Limited Vision After Stem Cell Transplants

Alternatively, if you favoured natural selection, this could be a case of pleiotropy. Further research would be needed to find out if the opsin gene was providing any benefit to the beetle. Futuyma says Darwin did allow himself some 'wriggle room'. He says despite not knowing about genes, Darwin anticipated neutral theory when he wrote about 'fluctuating variation' — where traits such as those for different eye colour didn't affect the success of the organism.

At any rate, says Futuyma, evolution has moved on since the 19th century and we shouldn't have to reconcile all our observations with Darwin's theory. If Darwin read my text book on evolution he wouldn't understand it.

Timeline of ophthalmology

He'd have to take an introductory biology course first and learn about DNA. Use these social-bookmarking links to share How does evolution explain animals losing vision? Use this form to email 'How does evolution explain animals losing vision? By clicking 'Send to a friend' you agree ABC Online is not responsible for the content contained in your email message.

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