The eyes are the most sensitive and complicated organs in the human body. Therefore, they are susceptible to several types of disorders, including glaucoma, infections, inflammatory and allergic conditions, as well as common Dry Eye syndrome. Eye preparations are applied to the eyes to provide therapeutic concentrations, while using the lowest effective dose and thereby minimising the risk of local and systemic adverse effects.
Glaucoma is an irreversible, progressive eye disease in which the optic nerve at the back of the eye is slowly destroyed due to increased intraocular pressure (IOP). Common causes of ocular hypertension include blockage of the circulation of aqueous humour, its drainage, poor blood supply or structural weakness of the optic nerve.
One in 10 Australians over 80 will develop glaucoma. At present, 50% of people with glaucoma in Australia are undiagnosed. It is estimated that the cost burden in Australia will increase to $4.3 billion by 2025. Chronic primary open-angle glaucoma and acute closed-angle glaucoma are the two most common types. The major risk factors for developing glaucoma include family history, diabetes, migraine, short sightedness, long sightedness, previous eye injury, hypertension, prolonged steroid use and African or Latino ancestry.
There is no cure for glaucoma. The goal of therapy is to reduce the IOP and to prevent further disease progression. In the last decade there has been an increase in the number of drugs available to treat glaucoma; however the key strategy remains the reduction of intraocular pressure by decreasing aqueous humour production or increasing aqueous humour outflow. There is no threshold for the initiation of treatment or standard guidelines for the optimal target IOP. Treatment is adjusted based on close follow-up of visual field and optic disc damage.
The prostaglandin analogues (bimatoprost, latanoprost and travoprost) are replacing beta-blockers as first-line agents due to their effectiveness and long-term efficacy. Brimonidine or topical carbonic anhydrase inhibitors (brinzolamide, dorzolamide) tend to be used third line. Use of pilocarpine is declining, although it may still be useful as adjunctive treatment. Newer eye drops containing two drugs, such as timolol with a prostaglandin analogue have been developed to aid patient compliance.
Allergic and Inflammatory Eye Conditions:
Allergic conjunctivitis is a common eye problem in Australia. It can be triggered by pollens, cosmetics, contact lenses and solutions, house dust mites, and ophthalmic drugs. Clinical presentation includes itchy, red, watery eyes, and with swelling of the conjunctiva. Allergic conjunctivitis can be categorised into: seasonal (hay fever) and recurrent. Mild conjunctivitis may be managed with cold compression and frequent use of ocular lubricants. Topical treatments for moderate to severe symptoms include: decongestants, antihistamines, corticosteroids or non-steroidal anti-inflammatories. Cromoglycate eye drops can be used as a preventative measure, starting one month before hay fever season as it takes 3–6 weeks for its full effects.
Bacterial conjunctivitis is caused by common pyogenic bacteria, e.g. Staphylococcus, Pneumococcus or Haemophilus. It has rapid onset but most cases are self-limiting and resolve after 2–3 days without any treatment. Signs and symptoms include grittiness and a stringy, opaque, greyish or yellowish discharge that may cause crusty lids on waking up. Swabs for culture and sensitivity are usually not required. Cold compression and antibiotic eye drops (chloramphenicol) may be used to hasten recovery. Broad-spectrum antibacterial eye drops (ciprofloxacin, ofloxacin) are reserved for use in bacterial keratitis to prevent emergence of antibiotic resistance.
Viral conjunctivitis is often associated with upper respiratory tract infection, common cold, and sore throat. Patients often present with watery and itchy eyes. It is infectious until redness and weeping resolve, normally within 10–12 days. Cold compression and regular artificial tears eye drops may help to alleviate symptoms. Topical antiviral eye drops are not indicated for use in viral conjunctivitis (aciclovir eye drops are only indicated for the treatment of herpes zoster keratitis).
Blepharitis can be classed into seborrhoeic blepharitis and Staphylococcal blepharitis. The symptoms can be recurrent and don’t always respond to antibacterials. Warm compresses and daily eyelid cleaning with mild soap (1:10 diluted baby shampoo, or Lidcare®) or dilute bicarbonate solution (one teaspoon: 250mL hot tap water) may help with the symptoms and prevent recurrence. Weakly amoebistatic eye drops (propamidine, Brolene®) are available over-the-counter for treatment of blepharitis.
This is an acute Staphylococcal infection of a sebaceous gland causing pain and swollen eyelids. Hot compresses help relieve the pain and encourage the stye to burst. Antibacterials are usually not needed.
Dry Eye is caused by reduced tear production or increased tear evaporation. Symptoms include irritation, stinging, burning, itchiness, grittiness, pain, redness of the eyes and blurred vision. It is common in the elderly and in post-menopausal women. Secondary causes may include climate, contact lenses, Sjögren’s syndrome, rheumatoid arthritis or adverse drug effects (e.g. anticholinergics, oral contraceptives, isotretinoin), lifestyle (e.g. prolonged computer use, flying, eye surgery).
Ocular lubricants/artificial tears in the form of drops, gel or ointment are used to provide symptomatic relief. No one lubricants’ drop is superior to another, and trial and error may be needed to find a suitable product for a patient. Regular administration (upto hourly) of eye drops is recommended if Dry Eye symptoms are severe. Multidose eye drops contain preservatives such as benzalkonium chloride (most irritant), polyquaternium, sodium chlorite, sodium perborate (less irritant) may irritate the cornea and further aggravate Dry Eye syndromes. These products should be avoided in patients with severe Dry Eye.
Preservative free eye drops are more expensive and bulkier for storage. Lecithin spray (Tearsagain®) is available on a PBS authority prescription for treatment of severe Dry Eye syndrome in patients who are sensitive to preservatives in multidose eye drops. It is sprayed onto closed eyes 3 to 4 times daily. It works by stabilising the eye’s lipid layer and thus reducing tear evaporation.
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