Ophthalmics Essay

explanatory Essay
1162 words
1162 words

OPHTHALMICS 1. INTRODUCTION Ophthalmics are the sterile liquid, solid or semi- solid preparations may contain one or more pharmaceutical ingredient (s) intended to be administered onto the internal, external surface of the eye or adjacent to the eye. These are essentially free from foreign particles or viable microorganism, suitably compounded and packaged for easy instillation into the eye. The excipients added should not affect the stability of the product and the availability of the active ingredients at the site of action. Coloring agents are not recommended for ophthalmic preparations. Ophthalmic products can reside in the eye for few seconds to hours to months or even years based on the type of dosage form. Based on the site of administration, ophthalmic preparations are named as • Topical Preparations – administered to the external surface of eye. • Intraocular Preparations – administered inside the eye. • Periocular Preparations – administered adjacent to the eye. Ophthalmics are used therapeutically or prophylactically. Therapeutically these are used in the treatment of dry eye, glaucoma, infections of eye or eyelids, intraocular or surface conditions like conjunctivitis or inflammation. Drug categories that are used therapeutically includes miotics, mydriatics, anti – virals, antifungals, antibacterials, anaesthetics, astringents, cycloplegics, vasoconstrictors etc. Ophthalmics used for prophylactics includes post-surgical /post –trauma preparations to prevent or to reduce the risk of infections and surgical accessories which helps to keep the delicate cells healthy. Multidose preparations of ophthalmics include a suitable antimicrobial agent. The important characteristic requirement for all type of ophthalmic product... ... middle of paper ... ... consists of lacrimal glands which secretes tears. Tear is a clear watery fluid secretion which consists of numerous salts, glucose, some organic compounds, some proteins and the enzyme, lysozyme. Tear fluid helps in lubricating and cleansing the eye under normal conditions. It also maintains a thin fluid film which covers the cornea and conjunctiva. Excess of tear fluid enters into the lacrimal lake from where it is drained by the lacrimal canaliculi (a small tube which leads to the upper part of nasolacrimal duct). The lysozyme present in the tear fluid keeps the cul-de-sac sterile, i.e. free of pathogenic organisms. This enzyme acts by destroying saprophytic organisms largely and pathogens to a smaller extent. In diseased conditions the characters of lacrimal fluid gets altered and this may lead to dryness, burning sensation and other general discomfort in eye.

In this essay, the author

  • Explains that cornea is the outermost membrane of about 0.5 to 1mm thickness, has no blood vessels and gets nutrition through the passive diffusion from the surrounding tissues and aqueous humor.
  • Explains that 90% of the cornea is composed of corneal epithelium and separates it from the stroma.
  • Explains that it comprises about 76-80 % of water and collagen fibrils. it is hydrophilic in nature without junctions, making it as a barrier to lipophilic molecules.
  • Evaluates the biocompatibility of ophthalmic preparations that are to be used in endothelium.
  • Explains that the conjunctival membrane covers the inner and outer surface of the eyelids. it permits the free movement of eye balls and allows sub-conjunctional injections, and generates mucus and facilitates lubrication.
  • Explains that the anterior and posterior chambers of the eye are divided by a muscular tissue rich in blood vessels that regulate the entry of light into the backside.
  • Explains that it is a ring-shaped muscle attached to the iris which controls the lens accommodation. its anterior portion which faces the posterior chamber of eye produces the humor.
  • Explains that it is a layer of clear fluid/gel like materials interposed between the solid structures. it acts as the carrier of nutrients, substrates and metabolites for the vascular cells of the eye.
  • Describes the lens as a flattened sphere connected to ciliary body, composed of crystalline fibers. it is flexible and can change the shape to adjust the focal length.
  • Explains that the tough opaque fibro-elastic capsule surrounding the eye ball supports and protects the interior structures of eye. it acts a lipophilic barrier as it contains no junctional complexes.
  • Explains that the retina is a highly vascularized tissue that provides nourishment to the photoreceptor cells.
  • Explains that it is a bi-layered tissue composed of complex photoreceptor cells that transform light into an electrical signal.
  • Describes a transparent gelatinous/jelly-like material or hydrogel matrix distributed between retina and lens, which fills the larger area at the backside of the eye.
  • Describes the sclera membrane as a thin membrane that separates the eye from the surrounding socket for freedom of movement.
  • Explains that ophthalmics are sterile liquid, solid or semi-solid preparations, free from foreign particles or viable microorganisms and packaged for easy instillation into the eye. coloring agents are not recommended.
  • Explains that ophthalmics are used therapeutically or prophylactically in the treatment of dry eye, glaucoma, infections of eyelids, intraocular or surface conditions like conjunctivitis or inflammation.
  • Explains that eye is a globe suspended in the ocular orbit through an arrangement of multiple tissues.
  • Explains that it accounts for 10% of total cornea composed of 5-7 layers of stratified epithelial cells. it is lipophilic in nature and has tight junctions which make it an effective barrier to hydrophilic and high molecular weight molecules and foreign substances.
  • Explains that tears are a clear watery fluid secretion which helps in lubricating and cleansing the eye under normal conditions.
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