As a vitreo retinal specialist, Dr Cassar concentrates on the internal structures of the eye, and he specialises in the medical and surgical treatment of disorders involving the retina, macula and vitreous, for example macular degeneration, diabetic eye disease and retinal detachments.
Age Related Macular Degeneration (AMD)
The retina is a light sensitive layer of tissue located at the back of the eye. The retina receives the light that has been transmitted through the lens, and then sends these electrical signals, via the optic nerve, to the brain. The retina is sometimes described as the screen upon which the visual images are projected.
The macula is part of the retina and is found near the centre of the retina. The macula is responsible for sharp, coloured, central vision. The rest of the retina is generally for peripheral vision. The macula is about 4mm in diameter.
AMD is a disease that affects the macula and fine detailed central and colour vision is affected. AMD does not affect peripheral vision. Someone with significant AMD will often have dark or empty patches in their central vision. It often causes distortion of straight lines (they appear wavy).
AMD usually affects people over 50 years of age and is a common cause of severe vision loss in people over 75 years of age. A family history of AMD and smoking increases a person’s risk of developing the condition.
There are two types of AMD. Dry AMD and Wet AMD
Dry AMD is relatively slow progressing and is caused by retinal cells dying through the aging process. Unfortunately no treatment is available. Supplements may be taken to slow progression. Regular monitoring is required as it may develop into Wet AMD.
Wet AMD is fast progressing and is caused by abnormal blood vessels growing into the retina. These vessels leak fluid into the layers of the retina resulting in decreased central vision. Prompt treatment is necessary. Treatment usually involves regular injections into the eye. The injected medication reduces fluid leakage and slows growth of new blood vessels in the retina. Injections are usually required at a regular cycle. There are several options for the medication used in the injections – the most common in Australia are Lucentis®, Eylea® and Avastin® and recently approved Beovu©.
Laser treatment is also an option in select cases. The laser is used to seal and stop or slow the progression of the abnormal retinal blood vessels. Laser may be used alone or in conjunction with injections depending on the situation.
With all treatment options, patients should monitor their vision every day with an Amsler grid. Even if vision has stabilised or improved, treatment may still need to be continued to ensure it does not progress.
Patients even with end-stage macular degeneration can be helped by visual aides and in certain circumstances with a special intraocular lens to help with reading. Dr Cassar with the pioneering surgeon in Queensland to offer this surgery to his patients.
Epiretinal Membrane (ERM)
The retina a light sensitive layer of tissue located at the back of the eye. The retina receives the light that has been transmitted through the lens, and then sends these electrical signals, via the optic nerve, to the brain. The retina is sometimes described as the screen upon which the visual images are projected.
The macula is part of the retina and is found near the centre of the retina. The macula is responsible for sharp, coloured, central vision. The rest of the retina is generally for peripheral vision. The macula is about 4mm in diameter
An epiretinal membrane is a very thin layer of tissue that forms on the surface of the macula. The tissue disrupts the macula by crumpling or puckering it, which causes distorted or blurred vision.
The tissue that forms over the macula is usually caused by vitreous detachment. The eye is filled with a jelly-like substance called vitreous. Vitreous contains microscopic fibres that are attached to the surface of the retina. If the vitreous pulls away from the retinal surface this is known as vitreous detachment. Vitreous detachment is normal and often there are no noticeable effects, but sometimes there is microscopic damage to the retinal surface and as this heals scar tissue is formed. When the scar tissue contracts it causes the retina to pucker – usually there is no noticeable effect, unless the scar tissue has formed over the macula – in which case central vision is adversely affected.
Epiretinal membrane development is linked to normal aging processes and most often occurs in people over 50. It can also be triggered by retinal tears, uveitis (inflammation of the eye), retinal vein occlusion or eye trauma. People with diabetic retinopathy are also more likely to have an epiretinal membrane form.
Symptoms vary widely between patients. Severe vision loss is rare. Usually vision is blurry or slightly distorted. Straight lines may appear wavy. Patients report difficulty reading fine print. Epiretinal membrane usually affects a single eye.
If symptoms are mild, treatment is generally unnecessary and patients adjust to the distortion. If vision is severely affected and there is a chance that surgery may improve vision then surgery may be performed. The surgery is called a vitrectomy and is performed by an ophthalmologist who specialises in vitreo retinal surgery.
Vitrectomy is usually performed under mild sedation and local anaesthetic. During a vitrectomy the vitreous inside the eye is removed and the scar tissue is also removed – this is called an ERM peel and is a very delicate procedure. The vitreous is replaced with a salt solution or sometimes a gas bubble, which will disappear after a few weeks as natural fluid is re-produced in the eye.
Surgery does not normally restore vision completely but in most cases vision is substantially improved. Recovery of vision can take 3 to 12 months. Vitrectomy surgery increases the risk of a cataract forming. The risk of developing glaucoma is also increased.
Intravitreal Injections
Intravitreal injections deliver medication via an injection through the white part of the eye, called the sclera, into the vitreous inside the eye. The vitreous is the jelly-like fluid contained within the eye behind the lens. The benefit of delivering this medication via intravitreal injection is that it is delivered near to the affected area within the eye.
Diabetic retinopathy, Wet Macular Degeneration and Macular Oedema may all be treated with intravitreal injections.
Intravitreal injections are performed in Dr Cassar’s rooms, or in some circumstances in day surgery.
The procedure itself is very quick. Prior to the actual injection, drops are usually placed in the eye to dilate the pupil. Numbing (anesthetic) drops will also be administered prior to the injection.
Intravitreal injections often need to be repeated. The frequency of the injections depends on the condition and response to treatment. Eylea© and Lucentis© are commonly used as intravitreal injections to treat wet macular degeneration and diabetic macular oedema They belong to the group of drugs called Anti Vascular Endothelial Growth Factor (Anti VEGF).
Intravitreal steroid (eg. Triesence) may also be required in particular cases of cystoid macular oedema (CMO). Diabetic macular oedema or CMO may also be treated by an intravitreal dexamethasone (Ozurdex) implant injected in Dr Cassar’s rooms.
A selection of cases of vitreo-macular traction (VMT) may also be treated with injectable medicine (eg. Jetrea).
Retinal Detachment
The retina a light sensitive layer of tissue located at the back of the eye. The retina receives the light that has been transmitted through the lens, and then sends these images, via the optic nerve, to the brain. The retina is sometimes described as the screen upon which the visual images are projected.
Retinal detachment is a sight threatening condition in which the retina separates from the back of the eye. Retinal detachments may be caused from retinal tears, proliferative retinopathy (eg. diabetes) and trauma to name a few.
Retinal detachments require urgent treatment. If left untreated, a retinal detachment could lead to permanent vision loss.
Retinal detachment is usually indicated by a sudden onset of persistent flashes and floaters. In addition, other symptoms may include sudden loss of central vision or a dark curtain or shadow that obscures part of the visual field.
Retinal detachments are treated with surgery. Depending on the specific circumstances the surgical method used to repair a detached retina vary. Surgical options include a vitrectomy, retinopexy or scleral buckle.
Vitrectomy surgery is commonly used to repair a detached retina. During a vitrectomy the vitreous jelly within the eye is removed and the retinal tears are treated with laser or cryotherapy. The vitreous fluid is then replaced with a gas bubble (alternatively a silicone oil bubble may be used). The gas bubble will eventually be absorbed and replaced with aqueous, an oil bubble needs to be surgically removed at a later date. The gas or oil bubble pushes the retina back against the back wall of the eye until the retinal tears are sealed up. Head positioning is often required for some days after the procedure to allow the bubble to be positioned and provide tamponade of the retina.
A vitrectomy surgery can be combined with a scleral buckle. A scleral buckle is where a buckle shaped silicone device is sutured to the outer wall (sclera) of the eye. The silicone buckle causes the eye to indent slightly which causes the back of the eye to push back onto the retina. A scleral buckle is usually left in place permanently.
Retinal detachment surgery is usually successful in saving some sight. However success depends not only on the surgery but also the duration, extent, type and location of the detachment. If the macula was involved, outcomes are usually adversely affected. Vision may be blurry for weeks or months after the surgery. Vision is usually never as good as it was prior to the detachment.
Vitrectomy Surgery
Vitrectomy is a surgical procedure, performed by a Vitreo Retinal surgeon, where the vitreous jelly inside the eye is removed to enable surgical access to the retina and/or macula.
The vitreous inside the eye has a sticky jelly like quality. The vitreous is located in the cavity behind the lens and in front of the retina. The cavity inside the eye that holds the vitreous is what gives the eye its round shape.
Removing the vitreous fluid from inside the eye enables access to the retina and other structures at the back of the eye. Once surgery has been completed the vitreous fluid is replaced with a gas bubble, saline or a silicone oil bubble. Over time, the body absorbs the gas and replaces it with aqueous fluid (an oil bubble needs to be surgically removed at a later stage).
Conditions that may require vitrectomy surgery include detached retina, proliferative diabetic retinopathy, dislodged intraocular lens, macular holes, Epiretinal membranes, complicated cataract surgery and more.
Vitrectomy is a very specialised surgery and is sometimes performed in conjunction with other eye surgery (such as cataract surgery). It can be performed under light sedation with an eye block or general anaesthesia depending on the circumstances.
Cataracts and Cataract Surgery
The lens of the eye is positioned inside the eye, behind the pupil and the iris. The lens inside the eye is usually clear. The lens is called a cataract when it becomes cloudy. A clear lens allows light to pass through it and a clear image to be received at the back of the eye on the retina. When the lens is cloudy the light cannot pass through as easily. The rays tend to scatter and the image received at the back of the eye is blurry.
Cataracts usually occur as part of the normal aging process, usually by the age of 70 most people have some degree of cataract but it is very variable and can occur at any age and are more likely to occur in patients who are diabetic; have had a previous injury to the eye; or have been using certain medications (such as prednisone). Very rarely, babies are born with cataracts (congenital cataracts). Patients who undergo surgery to the posterior (back) of the eye, such as a vitrectomy, also have a higher chance of developing a cataract.
Cataracts generally develop slowly. Symptoms can include blurry, hazy or foggy vision; sensitivity to glare and difficulty driving at night due (patients often describe seeing halos around on-coming headlights). Loss of contrast sensitivity is also common.
Most cataracts are not visible to the naked eye. Patients need to have their pupils dilated (using medicated eye drops) to properly assess the presence of a cataract. If a cataract is dense enough that obscures the view of the back of the eye other conditions, such as macular degeneration cannot be seen until the cataract is removed.
It is common to have cataracts in both eyes, but often one is more advanced than the other.
If you have been diagnosed with a cataract you may not need surgery straight away. The decision to have cataract surgery depends on how much the cataract is affecting your eyesight. In the early stages treatment may simply consist of adjusting your glasses prescription (often a person becomes more myopic (short sighted). Once it has been assessed that a patient’s cataract is adversely affecting their vision surgery is appropriate.
Surgery involves removal of the cloudy lens by breaking it into very small pieces with an ultrasound probe. An artificial lens known as an intraocular lens (IOL) is then inserted. The IOL is usually foldable and flexible acrylic, which enables it to be inserted through a very small incision into the eye (about 2mm). Usually stitches are not necessary. The IOL remains in the eye permanently and is fixed in place.
Cataract surgery is normally performed as day surgery under light sedation with local anaesthetic. Cataract is the most common eye surgery in Australia and has a very high success rate.
There are many different IOL options available today, however they are not all appropriate for every patient. Part of the cataract assessment involves tailoring the selected IOL to the patient as every IOL has advantages and disadvantages. IOLs that attempt to correct both distance and near vision are often not appropriate in patients with other eye disease.
Eye Pressure and Glaucoma
Your eye contains a watery fluid called aqueous. If the flow or drainage of fluid within the eye is disrupted, raised intraocular pressure (IOP) can occur. The fluid build up can put pressure on and subsequently damage the optic nerve at the back of the eye. Irreversible vision loss can occur.
Glaucoma occurs when raised eye pressure causes damage to the optic nerve and leads to loss of sight. A family history of glaucoma increases a person’s risk of developing the condition.
Glaucoma often has no warning signs in the early stages – usually a person’s other eye can accommodate for any vision loss. Damage to the optic nerve is irreversible and early detection is important.
There are a few different types of glaucoma. The most common is Open-Angle Glaucoma. The other types include Acute Angle-Closure Glaucoma (usually painful and sudden) and Normal Tension Glaucoma in addition to others. Glaucoma can also develop as the result of a previous eye injury or, for example, after long term use of cortisone medication.
Treatment options include medication (eye drops) and/or laser (including Laser Peripheral Iridotomy, Laser Trabeculoplasty). Sometimes cataract surgery is combined with microincisional glaucoma surgery (MIGS) when a small bypass stent is placed in the eye at the same time as cataract surgery.
Macula Oedema
The macula is part of the retina and is found near the centre of the retina. The macula is responsible for sharp, coloured, central vision. Macula oedema is swelling of the macula, usually caused by blood or fluid build up. Macula oedema is often caused by diabetic retinopathy, but can develop after eye surgery or in association with age related macula degeneration or retinal vein occlusion. Uveitis is also a risk factor.
Macula oedema can be treated with various intravitreal injections (Lucentis©, Eylea©, Beovu©, Avastin© or corticosteroid) and/or laser treatment – both are performed by Dr Cassar in his rooms.
Retinal Holes and Tears
The retina a light sensitive layer of tissue located at the back of the eye. The retina receives the light that has been transmitted through the lens, and then sends these electrical signals, via the optic nerve, to the brain. The retina is sometimes described as the screen upon which the visual images are projected.
A retinal hole is when a small tear or break develops in the retina.
Often retinal holes and tears may have no symptoms. Close monitoring of the condition is necessary as the hole or tear may cause fluid to leak behind the retina. The fluid may cause the retina to separate from the back of the eye – a detached retina which can lead to severe vision loss. A detached retina is a serious condition that requires urgent treatment.
Short sighedness (myopia), previous eye injuries, cataract surgery and a family history of retinal holes increase a persons risk of developing a retinal hole. Most retinal tears are due to a posterior vitreous detachment as part of the normal aging process in the eye.
Often retinal holes or tears have no symptoms. However if a person suddenly starts experiencing many floaters or flashes, or cloudy/wavy vision, or a dark shadow in their peripheral vision this may indicate a retinal tear or that the retina has detached and urgent assessment is needed.
Retinal holes and tears can be treated to decrease the chance of progression to retinal detachment. Treatment options include laser treatment (laser photocoagulation). Dr Cassar can perform this treatment in his offices. Cryopexy is also an option. A special device (cryoprobe) is used to freeze the tissue around the tear or hole and fix it to the inside of the eyeball. Some retinal holes require no treatment other than monitoring.
Treatment for retinal tears is usually successful – however a patient may develop further tears or holes later on.
Vitreo Retinal Surgeon
Dr Cassar is an ophthalmologist and Vitreo Retinal Surgeon. After completing his ophthalmic training in Brisbane, he undertook two years of additional specialist vitreo-retinal and medical retina training in the United Kingdom.
Vitreo Retinal specialists deal with conditions affecting the retina – such as age related macular degeneration, retinal detachment, diabetic retinopathy, macular holes, retinal tears and retinal vascular disease.
Diabetic Eye Disease
Diabetes is a condition that impairs a person’s ability regulate their blood glucose level, causing blood sugar levels to be too high. Diabetes can affect the entire body – causing damage to kidneys, increasing the risk of heart disease and stroke. Poorly managed diabetes, high blood pressure and kidney disease further increase the risk of complications.
People with diabetes have a higher risk of developing issues with their eyes – specifically diabetic retinopathy. Retinopathy is the term used to encompass diseases or conditions of the retina. The longer a person has diabetes and the more uncontrolled it is the higher the risk of developing diabetic retinopathy and diabetic macular oedema which are sight threatening. All people with diabetes should have regular eye examinations.
Diabetic Retinopathy is a condition in which the blood vessels of the retina are damaged and cause bleeding and swelling in the retina. Without treatment, diabetic retinopathy can lead to permanent vision loss and blindness.
Diabetic retinopathy progresses in stages and often affects both eyes. Patients with early stage disease are often asymptomatic. Once vision loss occurs the disease is well advanced.
Advanced diabetic retinopathy is also known as proliferative diabetic retinopathy. The blood vessels have continued to weaken and burst or bleed into the retina or vitreous. There is also abnormal growth of new blood vessels (neovascularisation) in the retina. The blood vessels bleed into the vitreous causing dark shadows and floaters. Scar tissue may also form on the retina – which increases the risk of a detached retina.
Diabetic Macular Oedema occurs when the leakage of fluid from the damaged retinal blood vessels affects the macula. The macula is part of the retina and is found near the centre of the retina. The macula is responsible for sharp, coloured, central vision.
Good control of diabetes, specifically blood sugar levels and blood pressure, is very important for managing the condition and preventing or slowing eye damage. Once the condition has advanced to the point it is adversely affecting vision there are a number of treatment options, depending on specific circumstances. The main options are laser treatment and intravitreal injections. In particularly advanced cases surgery (vitrectomy) may be required.
Flashes and Floaters
Flashes and floaters are common in people over 50. They are usually not harmful, however the sudden onset of flashes or floaters could be an indication of a developing issue (such as a retinal tear or detached retina) and should be reviewed urgently.
Floaters are opacities in the vitreous jelly inside the eye. They are usually described as dark shapes ‘floating’ in the field of vision. Flashes are caused when the vitreous body (which should be adhered firmly to the retina at the back of the eye) tugs on the retina. Often patients notice flashes in their side vision. Flashes can occur with or without floaters and vice versa. Flashing is often seen at night, in low or dim lighting.
Flashes can also be associated with migraines. Some migraines can be preceded by a ‘visual aura’. During a visual aura a patient may experience zig-zag flashing lights as well as have blurry or patchy vision. Symptoms usually resolve spontaneously within minutes or hours. Some migraine sufferers can experience a visual aura without migraine (without headache). This is known as ophthalmic migraine. Flashing associated with migraine are not true ‘flashes’ but can mimic flashing symptoms
Floaters are often left untreated as most will improve in time. If the floaters are particularly large and obstruct vision then they can be removed by a surgical procdure known as a vitrectomy. This is a surgical procedure where part, or all, of the vitreous jelly from inside the eye is removed and replaced with a saline solution or temporary gas, both of which are absorbed by the eye as it is replaced by the eye’s own aqueous fluid.
Flashes also usually don’t require treatment unless they are a symptom of a more serious underlying concern. If a retinal tear is present laser treatment (photocoagulation) or cryotherapy can be performed to decrease the chance of retinal detachment.
Macular Hole
The retina a light sensitive layer of tissue located at the back of the eye. The retina receives the light that has been transmitted through the lens, and then sends these electrical signals, via the optic nerve, to the brain. The retina is sometimes described as the screen upon which the visual images are projected.
The macula is part of the retina and is found near the centre of the retina. The macula is responsible for sharp, coloured, central vision. The rest of the retina is generally for peripheral vision. The macula is about 4mm in diameter.
A macular hole is a small defect (or break) in the macula. A macular hole usually presents as a painless decrease in central vision. As it progresses, patients may notice a small black or missing patch in their central vision.
The size of the hole and its exact location determines how it will affect the patient’s vision. If left untreated, a macular hole can lead to permanent central vision loss and sometimes a retinal detachment.
Most macular holes occur spontaneously or after vitreo-macular traction (VMT) – as part of the aging process the vitreous can pull away from the retina, causing a hole in the macula in the process. Eye trauma, severe myopia (short sightedness) and retinal detachment can also cause a macular hole.
Macular holes most commonly affect people over 60 years of age and more often women. If a macular hole has developed in one eye it increases the chances of developing it in the other.
Macular holes are usually treated surgically with a vitrectomy. Vitrectomy is usually performed under mild sedation and local anaesthetic. During a vitrectomy the vitreous inside the eye is removed to stop it from pulling on the retina and to gain access to the surface of the retina where a very thin membrane (internal limiting membrane) is usually removed to aide macular hole closure. The vitreous is replaced with a gas bubble which will tamponade against the macular hole to hold the edges of the hole together while it heals. The bubble will disappear after some weeks as natural fluid (aqueous) is re-produced in the eye. If the hole has been caused by VMT, in some special circumstances it may also be possible to try to treat it with an intraocular injection of Jetrea.
Surgery does not normally restore vision completely but in most cases vision is substantially improved. The longer the hole has been present the more likely vision will be permanently affected.
Retinal Vein Occlusion
Retinal vein occlusion (RVO) is where there is a blockage of the veins draining the retina. The retina is the light sensitive layer of tissue located at the back of the eye. The retina receives the light that has been transmitted through the lens, and then sends these electrical signals, via the optic nerve, to the brain. The retina is sometimes described as the screen upon which the visual images are projected.
When a retinal vein is blocked, blood servicing the retina cannot be effectively drained away, causing the area to swell and bleed. The effect on vision depends on the severity of the blockage and where exactly it occurs – it is particularly severe if it affects the central area of the retina, called the macula, as the macula is responsible for sharp, coloured, central vision.
Risks for a RVO include high blood pressure, high cholesterol, diabetes and smoking.
RVO will usually present as a sudden painless loss of vision in one eye. Vision loss due to RVO can be permanent. The sequelae of a RVO can include cystoid macular oedema and neovascularisation within the eye which are sight threatening.
Treatment options depend on the effect of the blockage. Intravitreal injections and laser treatment are commonly used. A corticosteriod implant (dexamethasone intravitreal implant – Ozurdex®) may also be a treatment option.