The human eye is a complex organ, some say second only to the brain, almost almond in shape, and very small in comparison to the rest of the body but it’s actions are remarkable.

An Iridologist mostly analyses the pupil, iris, sclera and cornea however having some idea about the layers of the iris will assists in understanding of what you’re seeing in the iris.

The human iris is very small compared to the rest of the body, but just like a drop of water can be reflective of the state of the motion and of the whole.

Iridologists are concerned with the fibres and pigmentation in the iris.

We believe the eye holds information for much more than just vision. The eyes are a map of the strength and toxic build-up in various parts of the body.

The iris may be likened to a curtain, as the outside of the eye is lighter, and the inner pigment is darker. The iris has also been called a “tapestry.”

The iris is made up of several layers from Anterior to Posterior :-

  1. Endothelial
  2. Anterior border layer
  3. This has colour or lack of colour. This is the top of the iris. This is what holds the pigment.
  4. Vascular layer = Stroma
  5. Posterior marginal / Dilator layer
  6. Epithelial pigment
  7. Retinal layer

Eye, brain, nerve connection

The eyes are connected to the brain and spinal cord and then all parts of the body.

The left iris is connected to right brain hemisphere and then crosses and connects to the left side of the body and vice versa.

The optic chiasm is an x-shaped division where the optic nerves divide and some nerve fibres cross over to the other side of the brain and some messages stay in the same hemisphere of the brain as the eye.

Anatomy and physiology of the eye

The eye consists of blood vessels, connective tissues and nerves and muscles with 28,000 nerve endings into the Iris from all parts of body.


We believe these nerves connect to the whole body which is why reaction fields appear in the iris.

In the back of iris is the optic nerve which is a bundle of over 1 million nerves that connect to the brain and spinal cord and then out to all organs of the body.


Think of the pupil as being the gateway for vision.

The pupil is the black part of the human eye. It is a hole that is connected to the brain via the optic nerve. It is positioned in front of the lens, but behind the cornea. The pupil is reactive to light. When there is not enough light to see clearly it dilates (expands), and when there is too much, it contracts.

This can be observed in other animals also. It is well known with cats, that at nighttime their pupils become very large and during the day it is as small as a slit.

Traditionally, through history, larger pupils have been considered an attractive quality and girls would use atropine, thorn apple or deadly nightshade (Belladonna) to dilate the pupil to look more attractive, in much the same way a skilled ophthalmologist would dilate the pupil to examine the eye.

Light needs to be passed through the pupil to reach the retina. The lens behind the pupil gathers the light like light directs it onto the retina.

Around the pupil is the pupillary border called pupillary ruff. That border is controlled by the back of the eye which rolls up around the pupil. The Pupillary ruff surrounds the pupil. It is the inner edge of the posterior [back] epithelial layer [posterior of the iris] which curls toward the anterior [front] aspect of the pupil encircling the margin of the pupil. The pupillary ruff is also called the pupillary border. The Border of the pupil is black.

The fringe around the pupil is a black extension of the dilator muscle which comes up from the back of the iris. The border is made of nerve tissue and connects directly to the brain through the optic nerve. The Border of the pupil is where we can observe a direct extension of the brain and spinal cord. It Indicates activities of the central nervous system.

The pupil is light-sensitive and lets the brain know when to direct the dilator muscle that comes from the posterior border layer to dilate the pupil in darkness so more light can enter. During bright light the pupil will signal the brain to active the sphincter muscle which is a donut shape just underneath the iris stroma to constrict the pupil to prevent too much light entering.

As the pupil connects directly to the spinal cord so it is affected by spinal fluid or injury to the spinal cord.

The pupil is normally off centre in the iris towards the midline of the body. The back of eye is the dilator muscle. The posterior epithelium is black which makes the pupil black. It rolls up and is run by the sympathetic nervous system. So, when in shock, the pupil opens wide.

The sphincter muscle, which encircles the iris is stimulated by the parasympathetic nervous system. The cells making up the pupillary dilator muscle are stimulated by the Sympathetic nervous system. The sphincter muscle, run by the parasympathetic nervous system, goes around the pupil. It contracts the muscle when there is too much light.


Covering the front portion of the eye, on top of the iris is the Cornea which is comprised of cells and proteins and looks like a glass dome. It bends or focuses light that enters the eye through the pupil. It has five layers epithelium which conveys oxygen and nutrients from tears to the remainder of the cornea; Bowman’s layer; the stroma; Descemet’s membrane; and the endothelium. As there are no blood vessels in the cornea (they may cloud the vision), nutrients are supplied from the aqueous humor and tears.

In the Anterior chamber, between the cornea and the iris as well as in the Posterior chamber between the Iris and the lens, is the Aqueous (thin, watery) humor which lubricates the eyes. The aqueous humor both gives the eye its shape, and as the area lacks blood supply it as well removes waste and supplies nutrients.

In the space between the lens and the retina at the back of the eye, is the Vitreous humor, a gel-like substance, consisting mainly of water with a little salt and collagen, that is clear enough for light to pass easily through. It is immobile and is not replenished.

The inside corner of eye is the medial canthus. The outer edge is called lateral canthus.

The lachrymal duct and sac are where tears flow from.


The iris is the disc shaped coloured part of the human eye with a hole in the middle called the pupil. Each iris fibre or trabecula [plural has ‘e’ on the end] is a blood vessel which is wrapped in a sheath = the structure of the iris or stroma which is beneath the pigmentation. Iris fibres collectively are called ‘the stroma’.

The iris is not a muscle, but made up of blood vessels.

Underneath the fibres is the posterior membrane or the posterior epithelium. This posterior membrane behind the iris rolls up around the pupil and when the pupil opens wide it causes rivets or ditches in the iris. The posterior epileitheum is black, when the fibres separate we can see the black showing through from behind that.

Anterior endothelium is the invisible layer of flattened cells on top.

The anterior border layer on top of the iris is where the pigment is located.

The blue iris lacks pigment, the dark brown iris has more pigment.

The sphincter is controlled by the sympathetic nervous system and dilates the eye.

Outside the Iris, and continuous with the clear cornea, and underneath the clear conjunctiva mucous membrane that lubricates the eye, is the white part of the eye called the Sclera.


Behind the pupil is the Lens which is shaped as a stretched out sphere (ellipsoid) and rounded outwards on both sides (biconvex). It is clear like glass. To make clear images of objects that are located at different distances, it works with the cornea to bend light and changes its shape to focus light rays that come through it onto the retina.

Ciliary muscle

The Ciliary muscle holds the lens in place through suspensory ligaments which enable the lens to stretch to be relatively flat for the eye to focus on distant objects or contract to become relatively round to focus on close objects.


The sclera is the white part of the human eye that is visible. It contributes to the eye having a spherical shape and acts as a protectant to the inner eye. It comes from the word sclerose (French) which means hard.

It is made of a protective fibrous outer layer made of elastic fibre and connective tissue.

It configures the reinforcing wall of the eyeball. It is divided into three portions:- loose connective tissue, beneath the conjunctiva (episclera); thickened white tissue that provides the colour (sclera proper); innermost sector of elastic fibres (lamina fusca).

It is thinner in babies, showing some of underlying pigment and so may appear slightly blue and
change to white around 6 months of age and thicken.

Blood vessels of the sclera lay mainly on the surface and mostly in the thin outer layers called the conjunctiva and episclera. It is the most sensitive part of the eye and will change more rapidly than other parts.

It may reflect and vascular conditions of body.

©Will Shannon, 2017