by Joseph San Laureano | Apr 11, 2013 | blog
Exciting news!
Melbourne Eye Centre will be adopting the new SMI toric alignment technology as part of the surgical workflow.
One of the most difficult aspects of both cataract surgery and refractive surgery, is the accurate alignment of a toric lens.
Furthermore, the position of the surgical wound and or timbal relaxing incisions is critically important and has profound impact on the final. post operative refraction.
This will be made significantly easier with a new eye tracker shortly to be introduced.
The device allows for a scan of the iris to be performed at the time of the consultation which is then “tracked” during surgery and ensures precision placement of surgical wounds and alignment of toric lenses.
Toric lenses in particular are very dependent on alignment as every 10 degrees of misalignment results in loss of 30% of the power of the toric. Thus a 30 degree would mean a complete loss of the toric power.
The link for more information is
by Joseph San Laureano | Apr 1, 2013 | Glaucoma
WHAT IS GLAUCOMA
Glaucoma is a relatively common condition which has a genetic component meaning that it can therefore be inherited.
Essentially Glaucoma is optic nerve damage which if left untreated can lead to blindness. The mechanism of damage is not clear but it is known that the pressure within the eye certainly plays a major role.
INTRAOCULAR PRESSURE
The eye is fluid filled and has an internal pressure. It also has a pressure regulating mechanisms. A good analogy is of a car tyre which is filled with air which results in a tyre pressure that can be measured with a tyre gauge. Within the eye there is a constant fluid production which flows throughout the eye and which eventually leaves via a drain. This drain is called the trabecular meshwork. If there is any obstruction to fluid leaving via this drain then pressure within the eye can rise.
The obstruction to fluid outflow can be mechanical, such as occurs in narrow angle glaucoma or due to abnormalities within the drain itself.
MANY TYPES OF GLAUCOMA
There are many different types of glaucoma and the classification is quite complex. It is important to realise that pressure is not always elevated and indeed a high pressure is not required for the diagnosis to be made.
Open angle glaucoma is the most common type of glaucoma seen in Australia.
The defining feature is that the trabecular meshwork (drain) is not obstructed by anything. In this type of glaucoma, the pressure within the eye can be high or it can be normal. High pressure open angle glaucoma, referred to as Primary Open Angle Glaucoma (POAG) is easier to understand in that the high pressure does damage. It is not well understood why the pressure is high but most likely due to increase outflow resistance in the trabecular meshwork. Low pressure of open angle glaucoma, called Normal Tension Glaucoma (NTG) is more complex in that the mechanism of damage is less well understood. It is thought that a number of other factors play a role in making the optic nerve susceptible to damage from even normal pressure.
Closed angle glaucoma is more common in Asia but still occurs in Australia. The next section covers it in more detail.
Glaucoma can also be due to obstruction of the trabecular meshwork by pigment (pigmentary glaucoma), pseudoexfoliative material (PXF glaucoma), red blood cells (Ghost cell glaucoma). Mechanical obstruction of the trabecular meshwork can also lead to pressure rises and therefore glaucoma such as by an large lens (phacomorphic glaucoma) or due to obstruction of the meshwork by leaking lens proteins (phacolytic glaucoma).
Additional causes include trauma, aphakic glaucoma, certain congenital conditions such as Iridocorneal endothelial syndrome (ICE).
DIAGNOSIS OF GLAUCOMA
Whatever the cause, the requirements for a diagnosis of glaucoma are optic nerve damage and visual field loss not due to another cause. An elevated intraocular pressure is not required for the diagnosis as seen in the entity of normal pressure glaucoma.
SYMPTOMS OF GLAUCOMA
Unless the intraocular pressure is extremely high, there are no symptoms of glaucoma. That is why it is often referred to as “The sneak thief of sight”. Vision starts to be lost in the peripheral visual field first where it can not be detected but with time it ultimately takes away central vision. Patients judge their glaucoma by their vision but unfortunately this is not a good way to tell as central vision is preserved until the end.
DETECTING GLAUCOMA
The only way to detect glaucoma is via an eye exam. Most commonly patients are pick up on a routine eye exam. Rarely patients notice that they are bumping into things and seek medical help or occasionally they develop pain and loss of vision from a high pressure which picks it up.
TREATING GLAUCOMA
Please see next section.
by Joseph San Laureano | Apr 1, 2013 | Cataract surgey
Figure 1. Cataract develops as we age
A cataract is the most common procedure that we perform. Simply because virtually everyone will get a cataract as they age.
A cataract is not a “disease” or growth as a lot of people think. It is simply the gradual loss of clarity of the human lens.
WHAT IS A CATARACT
Within everyones eye there is a lens. This lens focuses an image onto the retina. As you would expect this lens needs to be clear in order to see well but as we age it starts to become opaque.
When this happens the lens is referred to as a cataract. Thus a lens is just a cloudy, murky lens and not a growth.
An analogy would be a window which is clean so that you can see through it. If the window becomes fogged up then it is not possible to see through it.
SYMPTOMS OF CATARACT
Initially there may no symptoms or very subtle ones.
The slow nature of the vision deterioration means that we can adapt to the poor vision and not realize that it is poor. Sometimes even dipping below safety for driving. Eventually however, vision drops to a point that symptoms develop. These may be glare, specially when driving at night.
Figure 2. A cataract
Difficulty reading or difficulty watching television or seeing street signs. Invariably, a cataract left to progress will result in profound vision loss.
DEALING WITH A CATARACT
A cataract, being an opaque lens lens needs to be dealt with by removing it. There are many websites that you may have come across that promise to prevent or even dissolve cataracts.
These sites prey on the those who don’t understand what a cataract is. To date, other than surgical removal there is NO known method to solve the problem of cataract other than removal surgically and replacement with a new lens.
SURGERY FOR CATARACT
A cataract operation involves removal of the lens which has become cloudy and replacing it with an artificial lens. This is done in hospital and is a day procedure.
Modern cataract surgery is undergoing radical changes and at present can be perform by the conventional operation or by the more modern femtosecond laser assisted laser cataract procedure. The laser cataract procedure will in time replace the older method
Figure 3. Cataract surgery
Which ever method is chosen, anasthesia is done with local (topical) anaesthetic. A general anesthetic is not required.
The local anesthetic involves using eyedrops NOT an injection. An injection is still by some ophthalmologists but it has been largely surpassed by topical anasthetic.
As most people are anxious, a mild sedative is usually given to relax the patient but not to put them to sleep.
The procedure takes on average 30 minutes and at the end the patient goes home.
Visual recovery is usually rapid and indeed it is not unusual for patients to experience excellent vision even on the day of surgery.
More commonly it can take days to weeks for full visual recovery.
The next section goes into greater detail on the measurements required prior to surgery, the surgery itself and the long term results.
Figure 4. An intraocular lens
by Joseph San Laureano | Apr 17, 2013 | Why choose us
Every business has a view of themselves and have a philosophy that they follow. A lot have what they call their “Mission statement”.
Some practices have a view that they will cater for the lowest common denominator charging cheap prices and making up with volume. Bulk billing centers are good examples of this. You get little time, little explanation and really, little service in usually cheap and run down premises.
Other practices cater for the more discerning individuals who value their time and are looking for good quality service. These practices usually do not bulk bill but instead charge a fee. In return you get quality service, time spent with you explaining things and modern surroundings with up to date facilities and equipment.
We fall into the later category. We charge a reasonable fee and in return provide a quality service.
We prefer to cater for the discerning individual who values good service over cheap price. We find that these individuals are more motivated to get a good result and appreciate The extra effort that we put into them.
You will not find a cattle yard in our waiting rooms, and you will find that we definitely spend more time with you than other centres.
by Joseph San Laureano | Apr 2, 2013 | Glaucoma
Figure 1. Humphrey field analyzer
DIAGNOSIS
The diagnosis of glaucoma is made by the finding of the combination of a damaged optic nerve, visual field loss and sometimes elevated intraocular pressure although the latter is not required.
The most important part is the finding of the characteristic optic nerve changes.
In the early stages of glaucoma, there might not yet be sufficient optic nerve damage to result in vision loss. This is referred to as pre-perimetric glaucoma. Indeed the goal in glaucoma management is to detect glaucoma before it has had a chance to lead to loss of vision.
VISUAL FIELDS
As mentioned previously, glaucoma initially leads to loss of vision in the peripheral visual field. It can therefore not be detected in the early stages by the person with glaucoma.
In order to detect it a visual field test is performed. Unlike a vision chart which measures central or reading vision, a field analyzer measures vision in the periphery.
Unfortunately the visual field test is difficult to do, difficult for the technician to administer and therefore universally unpopular but a vitally important test.
Figure 2. Normal field
There are two types of visual fields. The most common is referred to as white-on-white because the test bowl is lit white and the stimulus target is also white. A second type is Short Wavelength Automated Perimetry (SWAP). This test uses a yellow lit bowl with a blue stimulus. This second type is used mainly to detect early glaucoma as it is able to pick up vision loss up to five years earlier than the conventional white-on-white.
OCULAR COHERENCE TOMOGRAPHY (OCT)
In glaucoma, cells galled ganglion cells die away. These cells have long axons that travel in a layer in the retina called the nerve fibre layer.
An OCT can measure the thickness of the nerve fibre layer around the optic nerve and can thus detect if there is loss of nerve fibres. An OCT is used in conjunction with an examination but is not a substitute for an examination. An OCT is also used to monitor the progression of glaucoma as further ganglion cell loss will lead to a thinning of the nerve fibre layer.
Figure 3. Glaucomatous field
PACHYMETRY
Pachymeters measure central corneal thickness. i.e how thick the front surface of the eye is. This is important for two reasons. Firstly it has been clearly demonstrated that a thin cornea (< 550 microns) is associated with a greater risk of glaucoma progression and an underestimation of the true intraocular pressure. The tonometers which measure intraocular pressure work on the assumption that the cornea is of average thickness.
A thinner than normal cornea will lead to an under measurement and a thicker than normal cornea will lead to an over measurement. Thus corneal thickness measurement is used as a prognostic factor.
OTHER INVESTIGATIONS FOR GLAUCOMA
Figure 4. Spectralis OCT
Other available tests include frequency doubling technology (FDT) and nerve fibre layer analyzers. SWAP and OCT makes these unnecessary.
DETECTING NARROW ANGLE GLAUCOMA
This is discussed in the next section.
Figure 5. OCT print out showing nerve damage (in red)
HRT II
