January 2021 - Armadale Eye Clinic

While some corneal infections result in only a mildly irritated eye, depending on the underlying cause and its location on the cornea, a corneal infection has the potential to severely impact eye health, causing permanent damage to your sight. A corneal infection can be caused by bacterial or viral infections, or be due to a fungus or microscopic parasite. In some unfortunate cases, an eye may be infected by more than one pathogen simultaneously.

The cornea is the front surface of the eye and must remain clear and transparent in order for light to pass through to reach the retina at the back of the eye and provide vision. Any disruption to this tissue, such as damage and scarring from corneal infections, can physically impede the passage of light into the eye, resulting in blurred vision. The cornea is also the most sensitive part of the eye, with a speck of dust being able to cause a great deal of discomfort.

Causes of Corneal Infection

A corneal infection is often referred to as keratitis, which translates to inflammation of the cornea. Although not all keratitis cases are necessarily active infections, all corneal infections involve inflammation at some point in their development.

Bacterial Infections

Most corneal infections are caused by bacteria, usually staphylococcus aureus or pseudomonas aeruginosa. Bacterial keratitis, in particular pseudomonas infections, can be aggressive and a significant threat to eye health, and so should be addressed promptly by an eyecare practitioner endorsed to prescribe antibiotic medications.

Risk factors for the development of a bacterial keratitis include contact lens wear, in particular when poor contact lens hygiene is practised, such as overnight wear or wearing a lens for longer than the recommended disposal schedule. Other underlying causes of compromised eye health can also predispose a person to bacterial keratitis, such as being immunocompromised or an eye injury.

Symptoms of bacterial corneal infections include mild pain, redness, and a mucous or pus discharge from the eye. You may also be able to see a round whitish opacity on the cornea, which is an ulcer caused by the infection. If this ulcer is large and central, or if there is significant discharge, you will also experience some effect to your vision.

Viral Infections

You may have heard of the herpes virus and adenoviruses in a context outside of eye health. However, these two viruses are in fact most commonly responsible for viral infections of the eye. Herpes simplex keratitis is caused by the type 1 herpes simplex strain of virus, the same strain responsible for causing cold sores around the mouth. It is also possible to get shingles in the eye in a condition known as herpes zoster ophthalmicus, caused by the varicella zoster virus of the herpes family. Once infected by a herpes virus, the virus remains in the body for life, typically lying dormant unless reactivated. Reactivation of the virus causes recurrent infection and inflammation, which can cause significant damage to the corneal tissues if not adequately managed.

Adenoviruses are a group of viruses often behind the common cold, causing characteristic symptoms such as fever, cough, and sore throat. Adenoviral infections of the eye are highly contagious and can be spread through droplets of bodily fluids left on surfaces, including tears.

Viral infections of the cornea typically present as a red, sore, watery eye with blurry vision. Patients also often report light sensitivity and in the case of adenoviral infections, may feel a burning or itching sensation in the affected eye. Viral keratitis is usually only on one side, though due to the contagious nature of the adenovirus, may transfer to the other eye in a matter of days if proper hygiene isn’t observed. Cases of herpes keratitis often have a history of cold sores or may have an active shingles infection along the scalp and face. Patients with an adenoviral infection may report having had a recent cold or flu or having been in contact with someone else with a cold or eye infection. Both a herpes and adenoviral infection of the cornea have the potential to cause scarring of the cornea, especially if recurrent.

Fungal Infections

Fungal keratitis is often more difficult to diagnose due to the slow nature of its development and the fact that symptoms typically present only days after the original infection. Many fungal eye infections also cause very little pain or irritation, which can further delay diagnosis and treatment, resulting in severe consequences for eye health and vision.

Contact lens wear is again a risk factor for fungal keratitis, as is an immunocompromised state. It is not uncommon for a fungal corneal infection to be caused by some sort of vegetative trauma to the eye, such as a scratch to the cornea by a branch or a leaf or dirt flicking into the eye.

Parasitic Infections

Parasitic keratitis is usually caused by a ubiquitous protozoan found in air, soil, and water, known as acanthamoeba. Acanthamoeba keratitis is uncommon, which is fortunate as the characteristic symptom of this infection is pain disproportionate to the appearance of the eye. Other symptoms include redness, watery discharge, and light sensitivity; however, these are typically mild in comparison to the pain reported. Acanthamoeba eye infections are an ocular emergency and must be treated promptly with potent antimicrobial eye drops to prevent permanent blindness.

Any suspect corneal infection should be seen immediately by an eyecare practitioner for proper diagnosis and management. Call us at (03) 9070 5753 today.

What is a Cataract?

A cataract refers to an opacity in the crystalline lens of the eye. This lens is located just behind the coloured iris and is usually clear and transparent to allow light to pass through. However, with time and age this lens gradually loses its transparency, becoming hazy or developing a discrete opacity – this is then considered a cataract. While advancing age is the most common cause of cataracts, other conditions or factors can cause a cataract or increase your risk of developing one, including:

Trauma to the eye

Metabolic diseases such as diabetes

Smoking

Certain systemic medications, such as steroids

As a complication of eye surgery, such as a retinal detachment repair

There are three types of age-related cataracts. Nuclear sclerosis appears as a yellowish-brownish haze in the centre of the lens, a section known as the nucleus. Cortical cataracts grow as spoke-like opacities in the cortex of the lens, which surrounds the nucleus. A posterior capsular cataract is an opacity at the back surface of the lens, further into the eye. Cataract symptoms will vary depending on the type and location of the opacity, though often there can be more than one type present in the eye simultaneously. Symptoms include glare sensitivity, blurred vision, altered colour perception, and increased difficulty with night vision. Nuclear sclerotic cataracts also have the potential to cause what’s known as a “myopic shift”, meaning that your contact lens or spectacle prescription becomes more short-sighted, or a higher minus script. Interestingly, this means that some patients find their reading vision improves without corrective lenses.

As a cataract tends to form very slowly in the eye, cataract symptoms may not become noticeable for years. This also depends on a person’s visual demands and daily activities as to how bothersome their eye cataract symptoms become. For example, a painter who requires very fine colour vision discrimination will likely be more affected by a milder cataract compared to an accountant who works on a computer and can easily enlarge their screen. A person’s visual demands and health of their eye guides cataract treatment timing. This leads us to the next question – what is the best treatment for cataract?

Eye Cataract Treatment

The only definitive treatment of a cataract in current medicine is surgical removal of the cataract. Your local optometrist will usually be the first to detect a cataract in the eye; cataract treatment is generally only recommended if the symptoms bother you enough to warrant intervention. Many early cataracts, and even moderate opacities, can simply be monitored. In most cases it’s not harmful to defer cataract surgery. There will be some instances where you may be advised to undergo treatment even if you’re still content with your vision – this includes situations where your vision no longer meets the legal visual requirements for holding a driver’s licence or if the presence of the cataract is affecting the pressure in your eye by blocking the drainage of fluid from the eyeball.

Once it’s decided that your cataracts are ready for surgery, your optometrist will refer you to an ophthalmologist for the operation. Cataract surgery is typically a quick and uncomplicated procedure with very high success rates in Australia.

The procedure is conducted under local anaesthesia; very rarely is a general anaesthetic used though many surgeons will offer a sedative if you’re feeling anxious or restless. A small incision is made at the edge of your cornea, which is the clear bubble of tissue at the front of the eye, to allow the necessary instruments to access the cataract inside. The cataract is then broken into fragments small enough to be suctioned out, leaving behind the capsular bag that used to hold this cataract. Different ophthalmologists will have a preference on the method of fragmenting the cataract, either with a technique known as phacoemulsification or a combination of phacoemulsification and the use of a femtosecond laser.

Once the cataract has been removed from the capsular bag, an artificial lens implant known as an intraocular lens (IOL) is then inserted in its place, which is designed to refract, or bend, the passage of light rays such that they focus clearly on the retina at the back of the eye. The power of this IOL is calculated before you undergo surgery and can reduce your dependency on glasses and contact lenses after the operation by accounting for your existing prescription, basically like having corrective lens implanted in the eye. Your surgeon will discuss your options of IOLs, which include:

Monofocal: correcting for one viewing distance, either near or far sight. Some patients may choose to have one monofocal IOL designed for long distance in one eye and a monofocal IOL for reading vision in the other, an arrangement known as monovision

Multifocal: these provide clear vision for multiple distances

Accommodative: designed to provide some degree of flexible focus to mimic your own eye’s ability to change focus

Toric: correct astigmatic prescriptions

If you’re concerned about cataracts, speak to Armadale Eye Clinic by calling us at (03) 9070 5753 for advice tailored to your situation.

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

Corneal Infection – Underlying Causes That Will Affect Your Eye Health

Causes of Corneal Infection

Bacterial Infections

Viral Infections

Fungal Infections

Parasitic Infections

Eye Cataract Treatment – What To Expect?

What is a Cataract?

Eye Cataract Treatment