In fact, there are eye drops that are also used for diagnostic purposes and during specialist visits (think, for example, of eye drops that cause mydriasis).
The solution or suspension that constitutes the eye drops is enclosed in single-dose or multi-dose containers which allow the product to escape in drops, in such a way as to allow easy application.
Nevertheless, after instillation of the eye drops it is not unusual to feel burning, discomfort and to witness an increase in tearing.
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There are also formal eye drops such as oily solutions; however, nowadays they are disused products.
in the aqueous vehicle; make the preparation more viscous; adjust the pH of the substance to that of the eye; prevent degradation of the formulation and / or bacterial contamination (preservatives); maintain the tonicity of the product; etc.
Maintenance of the isotony of an eye drop
In many aqueous eye drops, sodium chloride is present as an excipient. Its function is to bring the tonicity of the ophthalmic preparation to physiological values and, more precisely, to a tonicity equal to that of a 0.9% sodium chloride solution (the well-known "physiological solution"), therefore to a tonicity equal to that of tear fluid and plasma.
Maintenance of the pH of an eye drop
As regards the pH of the ophthalmic solution / suspension, in the formulation phase it is possible to add some salts which, by exercising a "buffering action, are able to maintain the pH at precise values considered optimal. In this regard, please note that" the pH of the tear fluid is similar to that of plasma and is around a value of 7.4. Unfortunately, however, it is not always possible to maintain the pH of the eye drops at these values. For this reason, in general, we try to create pH conditions which allow for the best stability and to maintain the effectiveness of the final formulation, but which, at the same time, result as less irritating as possible for the mucous membranes of the eyes.
It seems clear, therefore, how important is the choice of excipients that must be carefully selected to prevent them from interfering with the action of the eye drops and to avoid causing unpleasant side effects such as burning and redness.
Active Substances
The active substances contained in an eye drop can be different and vary according to the effect you want to be exerted by the final product.
Medicines in the form of eye drops will contain real active ingredients capable of carrying out a "pharmacological action. Depending on the active ingredient contained, the eye drops can be purchased freely (OTC or over-the-counter drugs, SOP or non-prescription drugs), or upon presentation of a specific medical prescription (repeatable, non-repeatable, etc.).
There are also eye drops not classified as drugs that may contain other active substances - such as, for example, plant extracts - with different properties, such as: anti-redness, emollient, soothing, lubricating or moisturizing properties.
). If after this period of time the eye drops have not been used at all, it must still be disposed of in the appropriate medicine container.
In the case of eye drops in multidose containers, however, the addition of preservatives necessary to prevent microbial contamination is essential. Clearly, the preservatives used must be compatible with the other ingredients present in the preparation and must be well tolerated by the ocular mucous membranes. in multi-dose packaging, unless otherwise indicated by the manufacturer, they generally have a shelf life of 3-4 weeks from opening, although there are exceptions (always refer to the information on the package leaflet). Also in this case, if after this time there is some product left inside the container, the eye drops must in any case be disposed of inside the special containers for medicines.
based on this classification.
Anti-redness eye drops
The eye drops recommended to prevent or reduce eye redness are generally isotonic solutions enriched with emollient and refreshing substances.
Eye drops for dry eyes
In the presence of dry eyes it may be useful to resort to the use of eye drops containing ingredients with a moisturizing, humectant and lubricating action.
Please Note
When redness and dry eyes are induced by causes of a pathological nature, the use of the aforementioned eye drops may prove to be ineffective, since they do not act on the factor triggering the symptom. In such cases, therefore, it is advisable to contact the doctor who will prescribe the therapy to the patient. most suitable drug for treating the underlying disease.
Allergy eye drops
In the presence of allergic conjunctivitis and keratoconjunctivitis it is possible to resort to the use of eye drops based on active ingredients with antihistamine and anti-allergic action in order to control the symptoms.
At the same time, it is also possible to resort to the use of eye drops based on active corticosteroid ingredients. Naturally, the doctor will prescribe the type of eye drops that best suits the needs of each patient.
For further information: Antihistamine eye dropsEye drops against bacterial infections
In case of ocular infections of a bacterial nature, the doctor may prescribe the administration of antibiotic eye drops.
For further information: Antibiotic eye dropsEye drops for Glaucoma
In the presence of glaucoma, the doctor may prescribe the use of eye drops or other pharmaceutical forms (for example, ophthalmic ointments, etc.) based on active ingredients such as:
- Beta blockers, to reduce intraocular pressure;
- Prostaglandin analogues, to favor the outflow of aqueous humor and decrease intraocular pressure;
- Sympathomimetics, able to reduce the pressure inside the eye (these substances mimic the activity of adrenaline and noradrenaline);
- Carbonic anhydrase inhibitors: by inhibiting the secretion of aqueous humor, they are able to reduce intraocular pressure.
Eye drops for inflammation
The eye drops used to combat inflammation can be made with active ingredients with anti-inflammatory action, namely, of the non-steroidal type (NSAIDs - non-steroidal anti-inflammatory drugs) or of the steroid type (corticosteroids).
Among the NSAIDs used in the preparation of eye drops we mention diclofenac and ketorolac; while among the corticosteroids we remember the dexamethasone, the hydrocortisone and the fluorometolone.
To learn more, read also: Types of Eye Drops.
Useful tips
- During the instillation of the eye drops, it is recommended to pay particular attention to avoiding the contact of the spout of the container with the eyelashes or, worse still, with the iris or an ocular structure. This precaution is important not only to avoid the risk of trauma or scratches to the eye, but also to minimize the possibility of ocular self-infection if multidose bottles are used.
- In the presence of contact lenses, the eye drops can be instilled into the eye only after removing them. Following the application of the eye drops, the contact lenses can be reapplied after at least 15 minutes (or after the time interval indicated on the leaflet. However, there are some pharmaceutical preparations that are also suitable for contact lens wearers.
- In case it is necessary to use more than one drug for ophthalmic use, it is recommended to administer the eye drops at a suitable time interval from each other. This time interval is usually reported on the package insert of ophthalmic preparations.
In any case, in case of doubts, please refer to the package leaflet of the eye drops that must be used and to consult with your doctor or pharmacist.
