CONCEPT OF EYE PREPARATION USES

EYE CARE

There are varieties of eye drops for various uses of eye diseases and defects. It is very essential to know how to use them for different purposes.

A BRIEF ANATOMY OF EYE 

                              

Eyelids are protecting the eyes. They are folds of tissues. They distribute tears.
The eyes can be divided into two parts.
The external eye is formed by the tear gland and the conjunctival cul de sac
The internal eye is composed of the followings:
1.The outer coating of the eyeball known as the sclera
2.The colored membrane of the pupil that regulates the light entering through the pupil known as the iris.
3.The fluid-like substance derived from the blood by a process of ultrafiltration and secretion, known as the aqueous humor
4. The transparent tissue hanging at the center balanced by ciliary tissues on either side is known as the lens. The lenses are light refracting, focuses light rays to form an image at the retina.
5. The tissue linings of the eyelids are known as the conjunctiva

6. In between the lens and retina space is filled with a thick viscous gel- fluid known as the vitreous body or humor. The vitreous is very important which keeps the eyeball in shape, keeps retina sufficiently apart from the lens so that the lens can produce a clear image on the retina. Any detachment or shrinkage in vitreous may cause blurred images and sight problems.

Unlike the aqueous humor which is more watery the vitreous is stagnant and more vicious. Any detached cells can float inside the vitreous and can be reflected in the retina as flying bubbles in front of us. A heavy blow in the head, or during faint the vitreous may get disturbed to form many virtual flys in front of us.

At the corner of the conjunctiva there is fine meshwork followed by a downward draining canal known respectively as trabecular meshwork and canal of Schlemm through which the aqueous humor can be drained out.

1.Anti-infective eye preparations 

The concept of anti-infective eye preparations such as 

1.sulpha preparations and antibiotics such as chloramphenicol, gentamicin, tobramycin, and polymixin trimethoprim combinations are used if an infection is found in the eyes.

A stye is a condition in which there are symptoms such as pain, tenderness, redness, and eye swelling may present. The style is a kind of eye infection involving one or more sebaceous(sweat) glands of the eyelid. More often without medication a frequent hot compress is enough to get relief from stye but some times it needs an antibiotic prescribed by a doctor.

Other eyelids inflammatory infectious conditions such as blepharitis whose symptoms are inflammation, redness, and itching of the eyelid certainly need antibiotic eye preparation.

The black eye is a condition there is a black stain surrounding the eye resulted in a blow that can often be treated with cold compresses for 24 hours followed by warm compresses. If eyelids are damaged a physician should be inferred.

Conjunctivitis, an infection of the conjunctiva(the white part of the eye).Symptoms are redness, burning, and pain needs antibiotic treatments.

Dacryoadenitis

It is the swelling of the tear glands due to infection. Symptoms include red burning eyes, and the sensation of a foreign body in the eye.
The following antibiotics alone or with some combinations are available as additional pieces of information:
1. Ofloxacin (Antibiotic) eye drops-This preparation can be used if an infection is present.
2. Gatifloxacin (Antibiotic) with Dexamethasone (Corticosteroid) Combination can be used if there are reddening and inflammation along with infection.
3.Hypromellose (Tears Naturale): Can be used in dry eyes.

2.Astringents

Astringents are substances that are chemical compounds that make body tissues tend to shrink and thereby relieve irritations and pain.

The only FDA approved astringent in the USA is 0.25% zinc sulfate in eye drops to be used to relieve eye irritations.Of course zinc sulfate is a mild astringent it is safe and widely used in medicine.

3..Demulcents

Demulcents are used to protect and lubricate the dry eyes give relief from light irritations. They are relatively free from side effects and can act as artificial tears.

The best examples are sodium carboxymethylcellulose,dextran-70,gelatin,glycerin,hydroxyethylcellulose,hydroxypropyl methylcellulose,methylcellulose,polyethylene glycol-300,polyethylene glycol-400,polysorbate-80,polyvinyl alcohol,povidone and propylene glycol.Whenever you tend to use demulcents check any of the above ingredients on the label.

4.Decongestants and Vasoconstrictors

These agents work by producing a temporary constriction of the blood vessels present in the conjunctiva and thereby relieve eye redness and pain.
Examples are naphazoline hydrochloride (e.g.Clear Eyes), phenylephrine hydrochloride (e.g.Isopto Frin),
tetrahydrozoline (Murine Plus) and oxymetazoline hydrochloride (OcuClear)
Combination decongestant and antihistamine products include Naphazoline Plus Solution, Naphcon-A, and Opcon-A.
Keep in your mind that continue the use of any of the above product may cause a rebound of the condition.
Decongestants and vasoconstrictors are contraindicated in angle-closure glaucoma patients.

5.Hypertonic Eye Drops

It is known that a 2 to 5% sodium chloride solution can be conveniently hypertonic to the lacrimal fluid. Hypertonic solutions are used to relieve corneal swelling.

Even though hypertonic solutions are available on the counter as nonprescription medicine it is advisable to use it under doctor's supervision because of its hypertonicity which may cause rupture of the cornea.

6.Artificial Tears

These are a combination of a hypertonic agent, buffering agent, an agent that causes viscosity, and a preservative.

In general OTC nonprescription eye products should not be used for more than three days.Any abnormal symptoms persists immediately the patient should be referred to a physician.

The followings are the usual contents of artificial tears:-

1.Carboxymethylcellulose or any methylcellulose compound as demulcents

2.Polyvinyl alcohol (A lubricating agent)

3.Hyaluronic acid (A viscosity agent)

4.Sodium chloride solution below 0.9%(as a hypertonic agent)

5.Sodium perborate (as an oxidative preservative)

It is advisable to use those eye lubricants without preservatives in mono-dose-vials to prevent harmful side effects.

Artificial tears are prescribed for dry eyes,keratoconjunctivitis sicca

PRESCRIPTION MEDICINES

1.Atropine 

First of all you must keep in your mind that in general atropine is an anti cholinergic antimuscarinic drug. It will block all acetylcholine muscarinic receptors and to pave the for adrenergic overactivity.

Hence using atropine in eyes causes dilation of the pupil and causes a decrease in eye sensitivity towards light. It is usually used during eye examinations.

The drug may relieve pain but should be dangerous if use without medical consent.

Atropine after application shall cause blurred vision for some times and do not rub the eyes. Since atropine causes high pressure due its anticholinergic effects and adrenergic overactivity in the eyes it should not be used by diabetics especially those who suffers glaucoma (both open-angle or close angle).

2.Cosopt eye drops:

This is a combination of two medicines a beta-adrenergic blocker(Timolol) and a carbonic anhydrase inhibitor (Dorzolamide).
The concept of using this eye drops is to reduce the elevated eye pressure and to relieve open-angle glaucoma. Untreated glaucoma and elevated will cause blindness.
The preparation should be used as per the medical advice.

Corticosteroid Eye Drops & ointments

Corticosteroids are immunity sparing drugs and should be used with caution.
Corticosteroids are used in eye preparation to get relief from inflammations, injuries in post-operative conditions, and in some other allergic conditions which need immunity compromises such as pain and swellings.
1.Dexamethasone (Maxidex)
2.Fluocinolone
3.Difluprednate
4.Fluorometholone (FML forte)
5.Loteprednol
6.prednisolone
7.prednisone
Whenever using eye preparations the following concepts are to be kept in the mind.
1. Thoroughly wash your hands and wipe them to dry.
2. Take the vial in your hand and open the lid.
3.Sit in a chair or sofa in a relaxed position and tilt the head up sufficiently supported by the sofa head at the back.
4. Pull the lower eyelid a little and without touching the eye get the vial nozzle sufficiently closer to the eye and direct it towards the corner of the eye just above the nose and press the vial to instill the medicine in drops and close the eye immediately.
5. To apply ointment no need of seat arrangements. Stand in front of a mirror and pull the eyelid little and apply for the medicine by slowly pressing the tube. Direct the tube nozzle towards the corner of the eye just above the nose and get it closer without touching the eye. Put the medicine started from the corner followed by the lower lid lining and blink the eyes.