Disorders of the Eye – Indications for Self-Treatment • Dry eye • Allergic conjunctivitis • Corneal edema • Loose foreign substances in the eye/minor eye irritation
Etiology of Ophthalmic Disorders • Ocular discomfort associated with dry eye disease is the most common condition for which non-prescription ophthalmic products are used • Dry eye disease affects 5 million people in the US ages ≥ 50 • Many common conditions associated with ocular discomfort are minor and self-limiting
Considerations for Intraocular Drug Delivery • Ambient tear volume of 7-10 μL on the ocular surface • Very little volume for drug delivery • Reflex tearing increases lacrimal production by up to 300% • Up to 90% of instilled drug dose may be lost • Avascular tissue • Cornea of eye is a largely avascular, which limits drug absorption
Pathophysiology of Ophthalmic Conditions •Dry eye: most often associated with aging, but can also be caused by lid defects, corneal defects, loss of lid tissue turgor, Sjogren’s syndrome, Bell’s palsy, thyroid eye disease, rheumatoid arthritis, and systemic medications•Allergic conjunctivitis: large variety of antigens that can cause ocular allergy, but the most common include pollen, animal dander, and topical eye preparations•Corneal edema: overuse of contact lenses, surgical damage, inherited corneal dystrophies•Loose foreign substance in eye: introduction of substances to the ocular surface such as dust, sand, hair, and other mechanical irritants (contact lenses)
Clinical Presentation of Ophthalmic Conditions •Dry eye: mild redness accompanied by a sandy or gritty feeling•Allergic conjunctivitis: red eye with watery discharge and itching•Corneal edema: fluid accumulation distorts optical properties resulting in halos or starbursts around lights•Loose foreign substances in eye: eye watering and feeling as if something is in the eye
Dry Eye - Treatment•General approach: ocular lubrication•Non-pharmacologic therapy: avoid environments that increase evaporation of the tear film (dry/dusty), use of humidifiers, stay away from heating and air conditioning vents, avoid prolonged screen viewing, use of eye protection in windy environments•Pharmacologic therapy: artificial tear solutions in combination with non-medicated ointments
Dry Eye – Ophthalmic Lubricants • Wide variety of artificial tear products • Commonly used formulations: hydroxypropyl methylcellulose, carboxymethylcellulose, polyvinyl alcohol, and povidone • Selection of appropriate product: all about the viscosity • Lower viscosity: shorter duration more easily diluted and drained • Higher viscosity: longer duration less easily diluted and drained • Products may contain combination of lower & higher viscosity substances • Dosing: once or twice daily (mild); TID-QID (more severe) • Max = QHourly • Ointments: normally applied QHS and contain petrolatum 60% and mineral oil 40%
Ophthalmic Preservatives • Destroy or limit growth of microorganisms • Can result in toxicity and irritation to eye • Benzalkonium chloride (BAK) adverse effects
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- Spring '14