# data[].attributes.body
In the past decade, new techniques have been tested and created to help treat the leading cause of blindness, cataracts¹. Cataracts are more common in elders and are develop in the clear lens in a person’s eye. Once cataracts develop, the lens becomes foggy and the eye can no longer focus light, therefore, creating a blurry image². Cataract surgery has been used for years to replace the now cloudy lens with an artificial lens³. Recently, Femtosecond Laser-Assisted Cataract Surgery has been used to help soften the cataract and relaxing the cornea to provide an easier surgery to remove the cataracts. With Kepler’s discovery of the inverted retinal eye, today cataract surgery is able to occur because the crystalline lens bends the light once again to display the image in the correct orientation⁴. This allows for people who are elder to continue seeing with a clear, artificial lens in the correct orientation.

Sources:
[1] https://www.nature.com/articles/s41598-022-08297-8
[2] https://my.clevelandclinic.org/health/diseases/8589-cataracts#:~:text=Cataracts%20are%20the%20clouding%20of,restores%20vision%20in%20nearly%20everyone.
[3] https://www.mayoclinic.org/tests-procedures/cataract-surgery/about/pac-20384765#:~:text=Cataract%20surgery%20is%20a%20procedure,which%20eventually%20affects%20your%20vision.
[4] https://www.verywellhealth.com/what-is-a-crystalline-lens-3422146#:~:text=When%20external%20light%20passes%20through,is%20formed%20on%20the%20retina.
Image https://trustedlasiksurgeons.com/lasik--cataract---vision-correction-procedures/femtosecond-laser-assisted-cataract-surgery.html

# data[].attributes.body
Leonardo da Vinci also added knowledge to our understanding of vision. In several images, da Vinci portrayed that light rays within eye cross two times, once behind the pupil and once through the lens. Through these findings, da Vinci the image is inverted twice, therefore when presented to the optic nerve, the image is right-side up¹.

Sources
[1], Image https://journals.sagepub.com/doi/pdf/10.1177/003591575504800512

# data[].attributes.attachment_caption
Christopher Scheiner's work on animal eyes led him to create an accurate representation of the eye.

# data[].attributes.body
Christopher Scheiner took Kepler’s work and provided experimental proof for the inverted retinal image. Scheiner performed various eye dissections using animals such as cows, oxens, etc. Scheiner performed a dissection on an oxen’s eye and found an inverted image on the cut-open retina¹. Furthermore, Scheiner was able to apply the knowledge from the various animal eye dissections to creating a representation of the gross anatomy of the eye. Scheiner found that “the optic nerve leaves the eye nasally². In 1619, Scheiner published ‘Oculus hoc est: fundamentum opticum’ with all his findings³.

Sources:
[1], [3], Image https://sciencemeetsfaith.wordpress.com/2018/07/25/christoph-scheiner-sj-sunspots-and-the-human-eye/
[2] https://opg.optica.org/josaa/fulltext.cfm?uri=josaa-24-5-1229&id=132174

# data[].attributes.body
Reńe Descartes depicts both Johannes Kepler’s work as well as Christopher Scheiner’s experiments. Soon after Scheiner published his book, Rene Descartes created a drawing depicting Scheiner looking at the retinal image on a dissected animal eye. This drawing was later published in Descartes' ‘La Dioptrique ¹.’

Sources:
[1], Image https://link.springer.com/chapter/10.1007/978-3-319-59641-9_1

# data[].attributes.headline
“Ad Vitellionem paralipomena quibus Astronomiæ pars optica traditvr”

# data[].attributes.subject
“Ad Vitellionem paralipomena quibus Astronomiæ pars optica traditvr”

# data[].attributes.body
In this image, Kepler’s first discoveries about the retinal image are written. Here, once translated, Kepler states “I say there is vision when a representation of the whole hemisphere of the world that is before the eye, and a bit more, fixes itself on the reddish white concave surface of the retina¹.” In this translation, Kepler discovers that the image being seen by the eye is reflected on the concave surface of the retina. Furthermore, as the book prolongs, several images are seen describing the eye as a camera. From Ludovico Cardi il Cigoli, a drawing of the anatomy of an eye is compared to a camera showing the retinal image².

Sources:
[1], [2], Image http://www.joostrekveld.net/?p=352

# data[].attributes.body
In 1604, Johannes Kepler wrote the book, ‘Astronomiae Pars Optica’ about the properties of light. Through this novel, Kepler applied these properties to the human eye and was able to predict the inverted retinal image that is observed. Kepler used this knowledge to explain how eyeglasses work, knowledge that is still used today when creating eyeglasses. Furthermore, Kepler furthered these discoveries to telescopes and was able to create the Keplerian telescope. In 1611, Kepler “replaced the concave eyepiece with a convex lens” and was able to see a wider view in the
telescope1.

Sources:
[1], Image https://collections.reading.ac.uk/special-collections/2016/03/17/johannes-kepler-astronomiae-pars-optica/

# data[].attributes.body
Johannes Kepler is the perfect “tour guide” for this museum exhibit. Kepler was a German astronomer known for discovering three major laws of planetary motion¹. However, Kepler also made landmark discoveries in other fields. An example being the basis of the exhibit, the inverted retinal image. In 1604, Kepler discovered the retinal image is inverted, meaning upside down on the retinal surface.

Kepler had completed several calculations of the retinal image and soon discovered that the image must be inverted. Kepler noted that the “relative positions of the elements of an object should be preserved in the image even though the image as a whole is inverted².”

Kepler was able to explain why this inversion took place and his discovery changed the study of vision as a whole. Through this discovery, future scientists were able to take this discovery further. A prime example of this is Christoph Scheiner, an astronomer, dissected an oxen’s eye to discover a small, inverse image³.

Sources:
[1] https://www.britannica.com/biography/Johannes-Kepler/Keplers-social-world
[2], [3] http://nivea.psycho.univ-paris5.fr/FeelingSupplements/InvertedRetinalImage.htm
Image - https://www2.hao.ucar.edu/Education/FamousSolarPhysicists/johannes-kepler