From the Scientific viewpoint, the human eye is a spherical organ almost exactly one inch in diameter, whose outer coating (the sclerotic) is composed of a tough vitreous material ideally suited for its task of protecting the inner parts of the eye. The front part of the sclerotic (the cornea) is the only transparent part, the rest being opaque white. The Cornea has a slight bulge that acts as the first stage of the refractive process. The light, entering the eye is therefore refracted (bent) to a limited extent by the cornea, after which it passes through a saline liquid known as the Aqueous Humour. This assists in the refractive process, and allows the light to enter the Lens at the correct angles. The Lens is made of successive layers of crystalline jelly, which by means of Ciliary Muscles, is enabled to change its shape, to vary the degree of convexity, to allow the rays of light to reach the back of the eye in sharp focus.
As the light emerges from the rear of the Lens, it traverses another liquid, known as the Vitreous Humour. Modern cameras make use of this principle of compound lenses in order to eliminate the effects of Chromatic Aberration, which, in simple terms is the trouble caused by different colours of light suffering different degrees of refraction, and therefore without correction would come to a focus at different distances from the Lens. Chromatic Aberration is eliminated by the progressive layers in the eye, Cornea, Aqueous Humour, Lens, and Vitreous Humour. Together they act as the eye Lens.
Just in front of the Lens there is a small “black hole”, through which the light passes. This is known as the Pupil. The diameter of the Pupil varies according to the light intensity by means of the Iris, the coloured part of the eye. Muscles operating within the Iris cause the diameter of the Pupil to change from about 2 mm for bright light to 8 mm for the darkest conditions.
At the back of the eye there is the Choroid, a blackened region, which prevents unwanted reflections from occurring within the eyeball. Embedded in the Choroid is the Retina, an assemblage of light-sensitive cells of two distinct types, known as Rods and Cones. The Cones enable us to see in colour, and about 2,000,000 of these are concentrated behind the Lens, around the Optical Axis of the eye. The Rods, being far more numerous (about 10,000,000) cover the rest of the inner surface of the eye behind the Lens. They enable us to see in dim light.
A yellow liquid is produced by the eye to change the ability to see in strong light to that of very dim light. This takes time to form, and explains why it is at first difficult to see anything in a darkened room after being in strong light. Full “dark adaption” may take up to ten minutes. Contrariwise, to emerge from a darkened room into full sunlight is hurtful to the eyes, and the reverse process has to occur, which is more rapid than dark adaption.
When we read, our eyes traverse the lines of print rather than staying static. This is because the most acute area of vision is contained within a minute part of the retina on the optical axis, known as the Macula Lutea, the “Yellow Spot”, an oval depression about one third of a millimetre across. The words need to fall within this Spot to be seen. Inside the Spot there are only Cones.
The dimensions of the Yellow Spot are those of the Golden Section, known to artists and architects, whereby “right proportion” is experienced. This is why a “landscape” picture of width 16 inches and height 10 inches “looks right” to the eye, simply because it fits within the oval Spot. The Golden Section is truly ubiquitous, found in such diverse areas as the Musical Scale, knobs on fir cones and pineapples, spirals in sea shells, and galaxies of stars.
Much more could be said about the exquisite design of the eye, a truly amazing piece of workmanship to cause a sense of wonder to anyone who has taken the time to study it. Let me quote what one scientist (surprisingly) said about the human eye –
“To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by naturalselection, seems, I freely confess, absurd in the highest degree.” [Charles Darwin, “Origin of Species”. Reprint of the 1859 edition by J.M.Dent & Sons Ltd, 1971. Page 167]
The Hebrew word for eye [AYIN] occurs 777 times in the O.T. and the Greek word [OPHTHALMOS] 101 times in the N.T. Such is its importance. Solomon said, “Truly the light is sweet, and it is a pleasant thing for the eyes to behold the sun, but if a man live many years, let him rejoice in them all, but let him remember the days of darkness, for they shall be many.” [Ecc.11:7-8] There is indeed spiritual sight as well as natural sight.
Truly the eyes are the Windows of the Soul. There is the “single eye” that Jesus spoke about; there is the “shifty eye” of the deceiver, and the “evil eye” of the self-centred, ambitious man. But of how much greater importance is the “spiritual eye”, which by God’s grace is enabled to “see” the divine mysteries of forgiveness, redemption, and eternal life. A blind man may possess such treasures, whilst those with human sight may pass by without awareness or recognition.