- Laser vision correction
- Dry Eye
The cornea is responsible for two-thirds of the focusing power of the eye
The cornea is the transparent front part of the eye that covers the iris and pupil. The cornea is surrounded by the white of the eye (slera) and performs three vital functions.
- It provides a strong outer coat for the eye that protects it from trauma and infection.
- It is transparent allowing visible light but not dangerous UV light to pass through to the back of the eye.
- It maintains a very precise shape tha refracts (bends) light so that a clearly focused image is seen on the retina. The cornea accounts for two-thirds of the eye’s total optical power. The lens, situated behind the iris, accounts for the remaining one-third.
The cornea needs to remain moist and will become painful, opaque and prone to infection if it dries out. Every time we blink the eyelids distibute tears across the cornea. Tears form in three layers, each of which must be healthy for optimum function.
- An outer, oily layer keeps tears from evaporating too quickly.
- A middle water layer makes up about 90% of the tear film and keeps the eye moist.
- A inner mucin layer helps fluid to remain on the surface of the cornea keeping it wet.
What can happen to the cornea?
The cornea can be affected by a number of conditions that can impact on you in terms of pain or loss of vision.
- Trauma can cause abrasions or damge to the surface of the eye causing pain, scarring or alteration in the shape of the cornea.
- Alterations in the shape of the cornea can cause refractive error and blurred vision.
- Infection can cause pain and subsequent scarring can cause opacification and loss of vision.
- A number of diseases can cause the cornea to lose transparency and blur vision.
- Exposure to UV light can cause growths from the edge of the cornea towards the centre of the eye, known as a pterygium.
Laser Vision Correction
People may need glasses if the shape of their cornea does not accurately focus light onto the retina.
If the shape of your cornea is too steep light will focus in front of the retina (short-sighted). If the cornea is too flat, then light will focus behind the retina (long-sighted).
Eye without refractive error
Most people who have a refractive error need to wear glasses or contact lenses to see a clear image.
Laser vision correction
A high-tech laser is used to re-shape the cornea. The laser is extremely precise and is able to shape the cornea to within several thousandths of a millimeter.
Modern lasers can not only alter the shape of the cornea to correct long or short-sightedness but can also correct astigmatism at the same time.
LASIK is the most common laser refractive procedure performed. A small flap is cut with a preliminary laser called the femtosecond laser. The flap is lifted allowing access to the underlying cornea. The extremely precise excimer laser is then able to re-shape the cornea without affecting the surface of the eye.
LASIK Surgery involves creating a flap
Is Laser Vision Correction Right For me
Who is suitable?
To be a suitable candidate for refractive surgery, you must be over 21 years of age. It is important that you have had no major change in your spectacle or contact lens prescription for at least 1 year.
Does it hurt?
LASIK is a popular choice for laser vision correction because visual recovery is rapid with minimal discomfort. Most patients can return to their normal activities very quickly.
Is it safe?
Laser vision correction is very safe with an extremely low rate of major complications. Dr Goh will undertake an extensive and complete examination of your eyes and advise you of any risk involved in laser surgery as well as your chance of achieving clear vision without glasses.
What is Pterygium
Pterygium is an abnormal growth of the conjunctiva (skin covering the white of the eye) over the cornea (Clear part of the front of the eye). Pterygium can be unsightly and painful.
Symptoms of Pterygium
Mostly pterygium does not cause pain. However, it can appear unsightly if it is large and grows over more than a few millimeters of the cornea. A pterygium can become inflamed, if this happens it may become red and sore.
A pterygium that grows very large can alter the shape of the cornea and cause astigmatism. This can reduce your vision and it may be difficult to correct the severe astigmatism from a pterygium with glasses.
Pterygium can be unsightly and painful.
Not all pterygiums require surgery. If the appearance does not bother you and it is not painful it may be best to leave it alone.
To minimise the risk of further growth and of the pterygium becoming inflamed it is important to use regular lubricants. Sun exposure should be avoided.
If the pterygium becomes red and painful you can use non-steroidal anti-inflammatory tablets or drops to help reduce the inflammation.
The pterygium is removed and graft site identified
Surgery is the only way to remove a pterygium and should be considered if:
- 1. The appearance bothers you
- 2. It is always or often painful
- 3. It is growing more than 2 mm onto the cornea
- 4. It is causing significant astigmatism
- 5. Prior to cataract surgery if it is large
Graft of healthy conjunctiva is sutured over the site of the pterygium
Surgery can be performed in a day theatre, a hospital or here in our treatment room at MCES.
Surgery involves removing the pterygium and taking a small patch of conjunctiva from under the upper eyelid. The conjunctival graft is then stitched or glued over the site of the pterygium to minimize the chance of re-growth.
What to expect after surgery
It is important to be aware that:
- your eye will be very sore for 1 week
- discomfort may persist for 1 month
The risks associated with surgery are minimal and your doctor will discuss these in detail. The greatest risk is that the pterygium will grow back, this can occur in 20% of cases.
A thin fluid film protects the surface of the eye (cornea) from becoming dry.
The tear film has three important layers:
- A mucous layer at the bottom allows it to ‘gripʼ to small attachments on the cornea.
- A water layer or tear film forms the majority of the thin film.
- An oil layer protects the water from evaporation and helps the tear layer spread across the eye.
Tear film deficiency
The tear film is generally produced in very small amounts by cells that live on the white of the eye and under the eyelids.
With age these cells become less effective. Exposure to sunlight, dust, excessive heat and recurrent eye infections can further limit the ability of these cells to do their job. Drying of the tear film can cause two major problems.
Tired irritated eyes
If the cornea dries out it will start to rub against the underside of the eyelids and will develop lots of small abrasions. These can cause a sensation of tiredness, irritation, grittiness, or even pain. If left untreated this can lead to the possibility of a serious corneal infection.
Watery dry eye
Some people produce tears from the lacrimal gland in response to dry eye—the same as crying. The production of tears from the lacrimal gland is uncontrolled and results in a watery eye. The regular use of lubricating drops, at least four times a day, is the best treatment.
Oil layer deficiency
Some patients with dry eye have a healthy production of the tear film, but the overlying oil layer is weak or absent. This causes the tear layer to rapidly evaporate and inhibits it from spreading over the surface of the eye. Glands in the eyelids produce oil. These glands can become blocked in blepharitis.
The regular use of a lubricant will help, but treatment should also be directed to improving the flow of oil from the glands in the eyelid.
Ask about IPL to treat blepharitis.
Herpetic Eye Disease
What is Herpetic Eye Disease
Herpetic eye disease is caused by a virus called Herpes Simplex Virus (HSV), the same virus that causes cold sores. In the eyes, it can cause infection or inflammation of the cornea.
Why does herpetic eye disease develop?
Many people have HSV living within their body. The virus lives in the nerve fibres of the body that supply the lips and eyes and generally donʼt cause any problems. Occasionally, the virus reactivates, and travels down the nerve fibres to start multiplying in the cornea or lips, causing herpetic eye disease or cold sores. This may happen when the bodyʼs immune system is weakened by some other health problem or stress.
Eye with Herpetic Eye Disease
How does herpes simplex virus affect the eye?
The cornea is most commonly affected by HSV. Infection affects the most superficial layer or skin of the cornea and is called epithelial keratitis. The bodyʼs immune system tries to kill the infection but sometimes this results in inflammation to the deeper layers of the cornea and is called stromal keratitis. Inflammation of these deeper layers is more serious because it can cause scarring of the cornea that can permanently blur your vision.
Detail of cornea showing patches of inflammation
Rarely HSV can cause inflammation of the iris and retina. Your eye may be dilated so that Dr. Joanne Goh can carefully check that your iris and retina are not affected.
Keratoconus and Cross-linking
What is Keratoconus
The cornea is usually an even round shape. Keratoconus occurs when the cornea thins and bulges forward in a cone shape.
What causes keratoconus
We do not know the exact cause of keratoconus, but it is thought to have a genetic component and occurs more commonly in people with allergies like asthma or eczema. There is also an association between eye rubbing and keratoconus.
Normal vs Keratoconic Cornea
How keratoconus affects your vision
The cornea is important for focusing light onto the back of your eye. In keratoconus your vision becomes blurred because the cornea cannot focus light properly.
Blurring of image
Scar on cornea
Scarring of the cornea
Keratoconus may also cause scarring of the cornea, which can severely decrease your vision by blocking light from entering the eye
What is the natural history of keratoconus
Keratoconus is often diagnosed in young people in their teens or twenties. Keratoconus is a progressive condition and can gradually get worse with time. For many it stops progressing in their mid to late thirties.
In the early stages of the disease glasses can focus the light for you. In more advanced disease special contact lenses are required and in severe cases even this may not be enough to focus a clear image.
Corneal cross-linking is a treatment that can stop keratoconus from getting worse by strengthening the cornea. It can be performed in the clinic here at MCES and is successful in over 90% of patients. It can also be performed in conjunction with laser eye surgery.
If it is no longer possible to give you clear vision with glasses or contact lenses, then you may require a surgical procedure to regain clear vision:
- Laser eye surgery
- Intra-corneal implants
- Corneal transplantation
At your consultation with Dr Joanne Goh a detailed assessment will determine the procedure that is most likely to give you the best outcome.
Less cross-linking leads to a weaker cornea
What is corneal cross-linking?
Corneal cross-linking (CXL) is a treatment that strengthens the cornea and stops keratoconus from getting worse. The treatment mimics the natural cross-linking that occurs when our corneas interact with the sun’s UV rays.
Who is suitable?
CXL is recommended for patients whose keratoconus is getting worse as demonstrated by corneal curvature scans. Patients over the age of 40 generally will not require CXL as keratoconus is unlikely to progress due to the natural cross-linking that occurs with age from extended sun exposure.
UV light treatment causes new cross-links to form
How is cross-linking performed
During the procedure, you will lie comfortably on a bed. Your eyelid will be held open with an eyelid clip. The surface cells of the cornea (the epithelium) is gently removed allowing the cornea to be soaked with Vitamin B2 (riboflavin) drops. UV light is then used to activate the riboflavin within the cornea, a process that induces cross-linking between the collagen fibres that make up the cornea, causing the cornea to become stronger.
A soft contact lens is placed over the cornea for 5-7 days at the end of the procedure.
How does cross-linking work?
CXL can be performed at MCES, in our treatment room, for those without health insurance. CXL can also be performed at the Manningham Day Procedure Centre for those with private health insurance or when combined with laser eye surgery. The procedure is painless and takes approximately 30 minutes per eye.
More cross-linking leads to a stronger cornea
Does it work?
Studies have shown that CXL increases corneal strength by up to 300% and is successful in stopping keratoconus from getting worse in over 90% of patients. It is currently the only treatment available to stop keratoconus from worsening.
Without CXL, 20% of patients with keratoconus will eventually require a corneal transplant. However, only 3% of patients who undergo CXL will require corneal grafting.
Will it improve my vision?
The aim of CXL is to stabilize keratoconus. This treatment alone does not attempt to improve vision. After treatment, you will still need to wear your glasses or contact lenses.
If your keratoconus has progressed to a point that you have a significant refractive error or corneal scarring, other treatment options may be required to improve your vision. In some cases, this can be combined with CXL. Dr Goh will advise you of the option that is most likely to achieve the best outcome for you.
What is a corneal transplant?
A corneal transplant involves replacing all or parts of your cornea with a healthy donor cornea.
Why would I need a corneal transplant?
The cornea is the clear window at the front of the eye which allows light to enter the eye and focuses light so that a clear image is seen. Various diseases or injury can cause the cornea to either become cloudy or out of shape, preventing the normal passage of light into the eye. A corneal transplant replaces your cornea with a healthy cornea to restore vision.
What types of corneal transplants are there?
Modern corneal transplantation utilizes techniques that replace all or a specific layer of your cornea. Where possible only the part of your cornea that is affected is replaced. Preserving the healthy parts of your cornea can have significant advantages over traditional surgery that replaced the entire cornea. A soft contact lens is placed over the cornea for 5-7 days at the end of the procedure.
The cornea has 3 layers:
- A thin outer layer
- A thick middle layer
- A thin inner layer
Different conditions cause damage within one, two, or all three of these layers. Utilizing different techniques, we can restore the outer and middle layer, the very thin inner layer alone or the entire cornea.
Penetrating Keratoplasty (PK)
If the entire thickness of the cornea is affected, then all three layers of the cornea must be replaced. A full-thickness donor cornea is used to replace the central portion of your cornea. Penetrating keratoplasty is the traditional form of corneal transplant and is still used when required but if some of your cornea remains healthy the goal is to preserve that healthy part of your cornea.
Deep Anterior Lamellar Keratoplasty (DALK)
DALK is considered if only the outer and middle layer of the cornea is affected (keratoconus). The outer portion of the cornea is replaced allowing us to preserve your healthy inner layer. The eye retains greater strength and is less prone to graft rejection.
Endothelial Keratoplasty (EK)
Also known as Descemet’s Membrane Endothelial Keratoplasty (DMEK) or Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK)
Endothelial keratoplasty is considered if only the very thin inner layer of the cornea is affected. Failure of this layer generally results in a swollen and cloudy cornea. Only the inner layer of the cornea is replaced. Visual recovery is much quicker, the eye retains greater strength, and you can return to your normal activities much quicker.
What can I expect after a corneal transplant?
Corneal surgery is a day procedure and most people go home on the day of surgery. Your precise post-operative care plan will depend on the type of surgery you have and any other ocular conditions you may have. Dr Goh will discuss the specifics with you prior to surgery. Most patient can expect to have 6 follow-up appointments over the first 12-months following a corneal transplant. You may need to take anti-rejection drops for an extended period of time.
How quickly will my vision recover?
Visual recovery depends on the type of corneal transplant performed. The modern partial thickness transplants have quicker recovery times. Dr Goh will advise you of your expected recovery time and what to expect during the recovery process.
Laser vision correction
Clearer vision without visual aids
Rapid recovery with minimal discomfort
Most advanced laser technology
Do you suffer from dry gritty or sore eyes? You may have Meibomian gland dysfunction (MGD). Fortunately, a new technology has emerged that can stimulate Meibomian glands and reverse much of the disease. Clinical studies have shown that over 80 per cent of patients with MGD will have significant improvement in symptoms with Intense Pulse Light treatment.
A revolutionary new treatment for sufferers of Dry Eye
Intense Pulse Light treatment is painless and safe. It does not require the use of injections or needles. The energy, spectrum and exposure time are precisely set to stimulate the Meibomian glands in order for them to return to their normal function. Call us today to find out about our exciting treatment options.