The Design of Eyes by Curt Deckert, PhD

by Curt Deckert CMC, MSME, MBA, PhD

Importance of eyes – Why we see

Scientists are only just beginning to understand the complete process of vision, the complexity of eyes, and the diversity of eye designs. Sight is essential for the survival of most living creatures. Most living creatures and some plants have eyes that appear to have been specially designed. Some only sense changes in light without seeing specific images; others sense high-resolution wide-angle images at long distances. Eyes are required not only for obtaining the necessities of life, but also for providing an important link to the world, enabling us to receive information. The eye-brain visual system processes most of our information input and links our inner being to the world.

How we see—Vision System Design Complexity

Eyes are adaptable visual sensors that enable us to see in a wide variety of situations. Images must be collected during movements that could cause blurred images. The electro-mechanical parts of eyes near and around the lens provide a means of tracking, adjusting light, and focusing.

It is known that animals react in a particular way when they see a specific scene, even though they do not have enough resolution to see fine details of that scene. Some creatures cannot recognize specific objects or color because they don’t have enough resolution or the right pigment to see specific color variations or adequate information processing capability. Others, such as some simple insects or marine animals, may see only enough to discern whether an object is moving across their field of vision.

Tracking, signaling, controlling eye direction, and maintaining focus capabilities are required for the eyes of most creatures. Here the brain controls where and how, as well as what they eyes “see.” The adaptable eye-bran visual system processes the information input from our eyes and then memorizes selective images.
Embedded image processing software in the brain and eyes is as amazing as the optical designs. The computing capability of eye visual systems could be likened to modular programmed FPGAs or other similar electronic devices.

“A field-programmable gate array (FPGA) is a complex integrated circuit designed to be configured by the customer or designer after manufacturing—hence “field-programmable”. The FPGA configuration is generally specified using a hardware description language (HDL), similar to that used for an application-specific integrated circuit (ASIC). FPGAs can be used to implement any logical function that an ASIC could perform. The FPGA has the ability to update its functionality to lower non-recurring engineering costs relative to an ASIC design.” (Wikipedia).

These hardware devices with their associated software illustrate some of the complexity required (sizes down to around 20 nm) for the brain’s computing power, for parallel image processing, image recognition, memory, and decision making. In the human brain it is estimated that there are some 1,000,000,000,000 neurons, each averaging approximately 1,000 synaptic connections. Read more: Driving Self-Recognition – The Scientist – Magazine of the Life Sciences http://www.the-scientist.com/article/display/57775/#ixzz16JcvuimU
One synapse may contain 1,000 molecular-scale switches. Because of the parallel computing, the human brain is more complex than present day computers. Each synapse then functions like a very small microprocessor, and tens of thousands of them can connect a single neuron to other nerve cells.

Embedded image processing software in “brains” includes memory searching, recognition of images, and decision making based on previously stored information. In our experience of the world, design, development, integration, and programming require an intelligent source. Therefore, it appears to this scientist that the eye and brain and their interactions were intelligently designed.

Evolutionary Eye Development

The evolutionary model of eye development may have blinded some to the possibility of investigating the design complexity of eyes. In fact, Charles Darwin stated the following:

“To suppose that the eye, with all of its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light and for correction of spherical and chromatic aberration, could have formed by natural selection, seems, I freely confess, absurd in the highest possible degree.”

Many of the eye variations discussed by Darwin are what is known as microevolution–inborn, heritable variations within a kind of animal–not different eye design themes and their applications for different purposes. In fact, Darwin himself could not address the complexity of eyes, the image processing of the brain, and the cellular control processes. He published his seminal work in 1859 and much of the science was not understood until this century.

Eye Design themes

There are approximately nine broad themes optical design and image processing.
Camera
Pinhole
Concave mirror
Apposition compound
Apposition-Neural superposition compound
Refracting superposition compound
Reflecting superposition compound
Parabolic superposition compound
Multiple sensor types and combinations of types

There are different speeds and objectives of optical recognition requirements for image information processing within each eye design theme—some simple and others extremely complex. The brain and eye seem to have the flexibility for adapting to environments so there are many elegant applications of these optical design themes according to kind of animal, size, environment, speed requirements, and purpose. This would occur by microevolution, which is a well-accepted theory. After all, physical size, resolution, spectral sensitivity, and image processing design differences of eyes do vary within most design theme categories. However, it does not seem to be feasible for random mutation and natural selection to allow the change from one design theme to another, which would require macroevolution. In addition, the fact that some so-called “early eyes” have very complex optics is unlikely to have occurred by the standard materialistic evolutionary mechanism.

Examples of Optical Design Complexity

When one tries to model the human eye using conventional spherical optics with constant index of refraction in each part of the eye, it is not possible to demonstrate the resolution capabilities of our eyes. The answer lies in the complex gradient index lenses found in many eyes. Commercial gradient index optical building blocks are relatively new to man-made optical systems. The use of gradient index materials in eyes indicates extremely complex material and cell reproduction and close control of the basic cellular building blocks in the eye lens. This produces an optical system equivalent to complex precise aspheric optics to correct spherical and chromatic aberrations. Precise eye cell reproduction to meet very specific gradual material changes within each pixel and cell of complex eyes is required. Even within some small insect eyes there are very precise gradient index additions to help provide additional optical correction of already complex optics. Beyond the eye lens– the retina also contains very advanced fiber technology to help provide good contrast at high resolution.

See EYE DESIGN Website for More Detail
Dr. Deckert offers a website www.eyedesignbook.com about vision includes descriptions, applications, and multiple examples of each of design themes. Besides containing many helpful eye and technical illustrations, the site asks compelling questions to challenge readers interested in science and technology.
curt@cdeckert.com