All Conditions of the cornea and their Causes, Epidemiology, Symptoms, Diagnosis and Treatment.

Conditions of the cornea
Causes
There are some minor conditions of the cornea for which pharmacists can offer advice and treatment. These are:
  allergic conjunctivitis (see Chapter 23)
  infective conjunctivitis, caused by:
–  viruses (mainly adenovirus or picornavirus)
– bacteria (usually Streptococcus or  Haemophilus).
  subconjunctival haemorrhage, caused by rupture of a conjunctival capillary causing spread of blood over the cornea. It looks alarming but it is painless, vision is not affected and it is usually of no signifi  cance. There is no treatment and the blood cannot be washed out of the eye
  dacrocystitis: the lacrimal sac, which drains tears into the nasolacrimal duct in the corner of the eye, becomes blocked or in young children may not open, and tears overfl ow. It may be cleared by gentle massage in the inner corner of eye, but if it does not clear, the patient should be referred.
Signs and symptoms
The features of minor corneal conditions are set out in Table
Differential diagnosis
Glaucoma
  Open-angle (chronic) glaucoma results from an increase in ocular pressure due to an imbalance between production and drainage of aqueous humour. It develops slowly and initially is symptomless, but eventually it produces headache and loss of visual fi eld. It affects both eyes and can cause blindness if not treated.
  Closed-angle (acute) glaucoma is due to obstruction to drainage of aqueous humour. It presents as severe pain in one eye, accompanied by headache, nausea and vomiting. Visual fi eld is reduced and haloes may be seen around lights.
Episcleritis
In episcleritis there is infl  ammation of the sclera, the tissue immediately beneath the conjunctiva, producing a localised patch of redness. It is usually painless or there may be a dull ache. It is most common in young women. It is self-limiting, but could take several weeks to resolve.
Scleritis
Scleritis is of similar appearance to episcleritis but much more painful. It is often associated with autoimmune conditions such as rheumatoid arthritis.
Uveitis (iritis)
Uveitis is infl ammation of the uveal tract (the structures around the iris). There is localised central redness, with pain and photophobia, and vision may be impaired. It may be associated with rheumatoid arthritis or ulcerative colitis.
Keratitis (corneal ulcer)
Infl ammation of the cornea is keratitis. There is severe pain with a watery discharge and photophobia. Redness is concentrated in the centre of the eye. It may result from trauma, long-term use of steroid eye drops or use of soft contact lenses.
Dry eye
Dry eye is a chronic condition, often associated with a systemic disorder such as rheumatoid arthritis. It may cause irritation and photophobia.
Symptoms and circumstances for referral
  pain in the eye, as distinct from superfi cial soreness, grittiness or itchiness
  redness localised to one area of the eye surface
  disturbance of vision
  pupils of abnormal shape or uneven pupils
  pupils reacting unevenly to light
  eye symptoms with headache and/or nausea/vomiting
  recurrent subconjunctival haemorrhage
dry eyes.
Essential criteria for distinguishing between minor and potentially more serious eye conditions are set out in Table
Treatment
Allergic conjunctivitis
Infective conjunctivitis
  Bacteria and viruses are both causes of infective conjunctivitis and it may be clinically diffi cult to distinguish between them. Over-the-counter treatment of any superfi cial infective conjunctivitis with an antibacterial agent is considered appropriate, as it may help prevent secondary bacterial infection.
  Non-prescription antimicrobial compounds available for the treatment of these infections are:
– chloramphenicol
–  propamidine and dibromopropamidine isetionates.
Chloramphenicol
  Chloramphenicol is active against a wide range of ocular pathogens. It has been the fi rst-choice prescription antibiotic for minor eye infections for many years, and chloramphenicol eye drops were reclassifi ed for pharmacy sale in 2005 for use for adults and children aged 2 years and over.
  Dosage is one drop into the infected eye every 2 hours for the fi rst 48 hours and then every 4 hours, during waking hours only. Treatment should be continued for 5 days, if symptoms improve.
  Chloramphenicol eye drops should not be used in patients hypersensitive to chloramphenicol, who have experienced myelosuppression during previous exposure to chloramphenicol or with a family history of blood dyscrasias, and it is not recommended for pregnant or breastfeeding women.
  Prolonged or frequent intermittent use should be avoided, as it may increase the likelihood of sensitisation and emergence of resistant organisms.
  The drops should not be used for more than 5 days, and patients should be referred if symptoms do not improve within 48 hours of starting treatment.
  As with all ocular antibiotic and most other eye preparations, contact lenses should not be worn during treatment and soft contact lenses should not be replaced for 24 hours after completing treatment.
  In the pharmacy, chloramphenicol eye drops should be stored in a refrigerator at 2–8°C. Once opened, the drops should be discarded after 5 days.
  In June 2007, chloramphenicol eye ointment was reclassifi ed from prescription only (POM) to pharmacy sale (P) for the treatment of acute bacterial conjunctivitis. Propamidine and dibromopropamidine isetionates
  Propamidine and dibromopropamidine isetionates are aromatic diamidine
antiseptics. They have been used for the treatment of bacterial conjunctivitis for more than 60 years and have always been available without prescription, but chloramphenicol is considered the drug of choice and the British National Formulary  regards propamidine and dibromopropamidine as of little value.
  Eye drops are formulated with propamidine isetionate 0.1% and eye ointment with dibromopropamidine isetionate 0.15%. Both can be used for adults and
children.
  The ointment persists longer on the corneal surface and needs to be applied only twice daily, but can cause stickiness and blurring of vision. Drops are used four times daily. Treatment should be continued for 24 hours after symptoms have cleared. If symptoms do not significantly improve within 48 hours, treatment should be discontinued and the patient referred for medical advice.
  Both products should be stored at room temperature and discarded not more than 1 month after opening.
Conditions of the eyelid
  There is one minor condition – stye (hordeolum) – for which pharmacists can offer advice and treatment. It is caused by staphylococcal infection of a hair follicle at the base of an eyelash.
  Principal symptoms are pain, redness, swelling and irritation. Initially, the whole of the lid may be affected, then swelling becomes localised, and a yellow pustule may develop near the lid margin.
  Treatment is with dibromopropanidine isetionate ointment.
Differential diagnosis and factors for referral
Referral should be made if any of the conditions described below are suspected.
Blepharitis
Blepharitis is chronic infl ammation of the lid margins, affecting both eyes. There are three main types: staphylococcal, seborrhoeic (frequently associated with seborrhoea of the scalp, eyebrows and ears) and contact dermatitis (due to cosmetics). The lid margins appear raw and red, with irritation, burning and itching. If contact dermatitis is the cause then there is generally a history of atopy, and other areas of skin may be affected. Scales are frequently seen on the lashes of both upper and lower lids, which tend to be dry in staphylococcal infections and greasy in seborrhoeic blepharitis. The lids become deformed in staphylococcal blepharitis due to ulceration. Lashes are frequently lost or may be distorted, turn inwards and rub on the cornea; this in turn can cause conjunctivitis. Mild seborrhoeic blepharitis can often be managed with eyelid hygiene without prescribed medication. However, medical diagnosis is always necessary fi rst and the condition may not respond to over-the-counter treatment.
Chalazion (meibomian cyst)
A chalazion is a cyst of a meibomian gland: the meibomian gland secretes fl uid to stop the eyelashes sticking together. It may become infected or develop into a sterile chronic granuloma, a fi rm, painless lump in the lid which gradually enlarges. Initially, the chalazion may resemble a stye but is not infl amed. Chalazia usually grow inwards towards the conjunctival surface, which may be slightly reddened or elevated. Infected cysts are treated as styes. A third of cases will resolve spontaneously and virtually all will resorb within 2 years, but they are often surgically removed before then.
Ectropion
This is mainly a condition of old age, as is entropion (see below). Sagging and turning outward of the lower eyelid occur from a natural loss of muscle tone and orbital fat. Tears overfl ow and there is insuffi cient lubrication and protection for the eye. The lower lid may become chronically infected and scarred. This then requires surgical correction.
Entropion
The lower lids turn inwards and lid margins and eyelashes abrade the surface of the eye. Lashes may fall out and susceptibility to infection is increased. Entropion requires surgical correction.
Basal cell carcinoma
Basal cell carcinoma presents as a reddish nodule on the eyelid. There is no pain or discomfort. There may be a history of prolonged exposure to sun or ultraviolet light.
Other eye problems
Sore and ‘tired’ eyes
  Redness and mild irritation in the eyes can be caused by activities such as driving and close work, and environmental pollutants, including tobacco smoke.
Several eye drop preparations, based mainly on astringents and vasoconstrictors, are available without prescription:
–  Several products contain distilled witch hazel (hamamelis water), obtained from the bark of a shrub, with astringent and anti-inflammatory properties.
–  Naphazoline, a sympathomimetic vasoconstrictor, is included in some ophthalmic preparations to shrink the dilated blood vessels that cause redness.
Dry eyes
Dry eye (keratoconjunctivitis sicca) is a chronic condition characterised by dryness of the surface of