Not only drugs: eye

Description

Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons.

In higher organisms the eye is a complex optical system which collects light from the surrounding environment; regulates its intensity through a diaphragm; focuses it through an adjustable assembly of lenses to form an image; converts this image into a set of electrical signals; and transmits these signals to the brain, through complex neural pathways that connect the eye, via the optic nerve, to the visual cortex and other areas of the brain.

-The eye is not properly a sphere, rather it is a fused two-piece unit. The smaller frontal unit, more curved, called the cornea is linked to the larger unit called the sclera. The cornea and sclera are connected by a ring called the limbus.

-The iris ( the color of the eye )and the pupil (its black center)are seen instead of the cornea due to the cornea's transparency.

-The fundus (area opposite the pupil) shows the characteristic pale optic disk ,papilla, where vessels entering the eye pass across and optic nerve fibers depart the globe.

The eye is made up of three coats, enclosing three transparent structures:

1. The outermost layer is composed of the cornea and sclera.

2. The middle layer consists of the choroid, ciliary body, and iris.

3. The innermost is the retina, which gets its circulation from the vessels of the choroid as well as the retinal vessels, which can be seen in an ophthalmoscope.

Within these coats are the aqueous humor, the vitreous body, and the flexible lens.

1. The aqueous humor is a clear fluid that is contained in two areas: the anterior chamber between the cornea and the iris and exposed area of the lens; and the posterior chamber, behind the iris and the rest. 2. The vitreous body is a clear jelly that is much larger than the aqueous humor, and is bordered by the sclera, zonule, and lens. They are connected via the pupil.

3. The lens is suspended to the ciliary body by the suspensory ligament (Zonule of Zinn), made up of fine transparent fibers.

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Eye irritation

Eye irritation has been defined as “the magnitude of any stinging, scratching, burning, or other irritating sensation from the eye”.

It is a common problem experienced by people of all ages. Related eye symptoms and signs of irritation are e.g. discomfort, dryness, excess tearing, itching, grating, sandy sensation, smarting, ocular fatigue, pain, scratchiness, soreness, redness, swollen eyelids, and tiredness, etc. These eye symptoms are reported with intensities from severe to less severe. It has been suggested that these eye symptoms are related to different causal mechanisms.

Several suspected causal factors in our environment have been studied so far:

-One hypothesis is that indoor air pollution may cause eye and airway irritation.

-Occupational factors are also likely to influence the perception of eye irritation. Some of these are lighting (glare and poor contrast), gaze position, a limited number of breaks, and a constant function of accommodation, musculoskeletal burden, and impairment of the visual nervous system.

-In addition, psychological factors have been found in multivariate analyses to be associated with an increase in eye irritation among VDU users.

-Other risk factors, such as chemical toxins/irritants, e.g. Amines, Formaldehyde, Acetaldehyde, Acrolein, N-decane, VOCs; Ozone, Pesticides and preservatives, Allergens, etc might cause eye irritation as well.

-Personal factors (e.g., use of contact lenses, eye make-up, and certain medications) may also affect destabilization of the tear film and possibly result in more eye symptoms.

- Contact lenses and gender differences, there are more and more people wearing contact lens now and dry eyes appear to be the most common complaint among contact lens wearers. Although both contact lens wearers and spectacle wearers experience similar eye irritation symptoms, dryness, redness, and grittiness have been reported far more frequently among contact lens wearers and with greater severity than among spectacle wearers.

The incidence of dry eyes increases with age. Tear film stability (eg. break-up time) is significantly lower among women than among men. In addition, women have a higher blink frequency while reading.

eye irritation was the most frequent symptom in industrial building spaces. Since the 1970s, reports have linked mucosal, skin, and general symptoms to work with self-copying paper. Emission of various particulate and volatile substances has been suggested as specific causes. These symptoms have been related to Sick Building Syndrome (SBS), which involves symptoms such as irritation to the eyes, skin, and upper airways, headache and fatigue.

Conditions of eye irritation
1 . Conjunctivitis (Pink Eye)

Conjunctivitis, or pink eye, is an inflammation of the conjunctiva. The conjunctiva is a clear mucus membrane that lines the inside of the eyelid and covers the white part of the eye. The most obvious symptom of pink eye is a red or "pink" colored eye. Inflammation causes small blood vessels in the conjunctiva to darken, resulting in a pink or red tint to the white of the eye.

2 . Eye Allergies

Many people complaining of eye irritation are diagnosed with seasonal eye allergies. Eye allergies sometimes cause significant discomfort, often interrupting daily activities with annoying symptoms.

3 . Dry Eye Syndrome

If your eyes feel dry, have a stinging sensation, or feel scratchy, you may have dry eye syndrome. Dry eye syndrome is a condition that can occur when the tear glands don't produce the correct quantity or quality of tears.

4 .Blepharitis

Blepharitis commonly causes red, crusty eyelids. If you have blepharitis, your symptoms are probably most noticeable upon awakening in the morning.

5 .Corneal Ulcer

A corneal ulcer is an erosion or open sore on the surface of the cornea. Corneal ulcers are common in people who wear contact lenses, especially if they wear them overnight.

Prevention of eye irritation

Several actions can be taken to prevent eye irritation:

.Trying to maintain normal blinking by avoiding room temperatures that are too high; avoiding relative humidities that are too high or too low, because they reduce blink frequency or may increase water evaporation.

.Trying to maintain an intact tear film by the following actions:

1) blinking and short breaks may be beneficial for VDU users.

2) downward gazing is recommended to reduce the ocular surface area and water evaporation.

3) the distance between the VDU and keyboard should be kept as short as possible to minimize evaporation from the ocular surface area by a low direction of the gaze.

4) blink training can be beneficial.

Treatment for eye irritation

Artificial tears eye drops