The retinal vein has blocked due to sluggish blood flowthrough the vein.
Retinal veins have thin walls and are crossed by retinal arteries. If you have hardening of the arteries, the thin retinal vein is kinked or partially obstructed by the hardened artery. This leads to sluggish blood flow in the vein and a blood clot results. The blood clot causes back pressure such that fluid and blood are forced out of the vein and into the retina. This causes retinal swelling and retinal haemorrhaging.
In branch retinal vein occlusions, if the macular is thickened and swollen, the vision will inevidably decline. If this is left too long, the macula can undergo irreversible structural changes. Therefore, in a Central or Branch Retinal Vein Occlusion (CRVO or BRVO) with swelling of the macula (macular oedema) Dr Bourke will want to improve the macular arcitecture to as close as normal as possible, as soon as possible. The new treatments with intravitreal antivascular endothelial growth factor agents (Anti VEGF such as Avastin or Lucentis) and intravitreal steroids work very well to successfully “dry out” the macula (central retina).
In most instances, Dr Bourke will recommend early treatment with an intravitreal injection of antiVEGF and/or steroid. Although retinal vein occlusion can be a devastating condition, fortunately the injections work most of the time to help dry out the macula and to improve vision. Often, for longer term benefit, follow up macular laser treatment is administered.
Other biological processes can develop as a result of BRVO/CRVO. Sometimes, new blood vessels grow into the eye (neovascularisation) and extensive laser treatment or vitrectomy surgery is required to remove blood or cause the blood vessels to shrink.
In some cases of CRVO, the occlusion is so severe that new blood vessels growing into the eye can lead to a severe form of glaucoma (neovascular glaucoma).
Dr Bourke will discuss your prognosis with you as each case is different. This new era of Anti-VEGF injections, laser and sometimes vitrectomy has lead to significantly increased prognosis.
If blood vessels in the retina are leaking fluid, this causes a thickening or swelling of the macula. There are treatments available, but earlintervention is again important.
The vitreous is the jelly-like fluid behind the eye. If it is filled with blood, this prevents light entering the eye. Symptoms include floaters, dots or blobs to complete vision loss. Vitrectomy surgery is available to restore loss of vision from vitreous haemorrhage.
Floaters and flashes occur when the vitreous detaches from the retina.
The vitreous will detach from the retina in almost everybody’s eye were we to live long enough. When this happens, the vitreous pulls on the retina to perceive a spark of light. The floaters are due to opacities in the vitreous, which is now able to swirl around in front of the retina, thus casting a shadow on the retina.
Recent onset of floaters and flashes indicate a need for a careful peripheral retinal examination, as retinal tears can occur during this period of change within the eye.
If no tear is found, no treatment other than observation is required. If a tear is found, laser or sometimes cryo-therapy (retinopexy) is necessary to make the torn retina adhere to the underlying tissue layer to prevent a retinal detachment. If fluid has leaked through the tear then a retinal detachment has occurred and surgery will be required.
Your doctor will advise you how frequently you need to be seen. If there is no tear in the retina, you can expect the flashes of light to continue for a couple of weeks and the floaters to slowly sink out of view over a period of months. You should contact your doctor if you have a sudden onset of new floaters or an increase in intensity or frequency of flashes of light. You should closely monitor your vision for a loss of visual field, which can be likened to a black curtain coming across the field of vision.
The vitreous is cloudy and prevents light focusing on the retina.
The vitreous can be cloudy due to blood cells (red or white) or sometimes due to other causes.
Vitrectomy surgery removes the cloudy vitreous, allowing a clear pathway for light to be focused on the retina. The surgery can be performed under local anaesthesia or general anaesthesia, depending on the patient and anaesthetist’s choice. If performed under local anaesthesia, the patient will be required to stay still for approximately one hour during surgery. The surgery is performed as a day case.
With clearing of the vitreous opacity, the eye can see better and vision is no longer like ‘looking through a haze’. Removing the vitreous cloudiness allows the doctor a clearer view of the retina, often enabling treatment to prevent further vitreous opacity occurring.
Most patients will develop a cataract within a few years of this surgery, which may require cataract extraction. A retinal tear is a complication that is searched for and treated (if found) at the time of surgery with laser. It is rare for a treated tear to cause problems, but if a tear is not adequately sealed, it can result in a retinal detachment, which can decrease vision and require further surgery. Severe complications, such as haemorrhage and infection, are rare, and can occur in association with any intraocular surgery (1 in 1,000).
Cystoid macular oedema refers to a swelling of the central retina. Essentially the central retina (macula) can become ‘waterlogged’ due to a number of different stimuli including recent surgery, vitreous contraction, epiretinal membrane, inflammatory eye disease, retinal vein occlusion, diabetes etc. Cystoid macular oedema is not a blinding condition but if left untreated, it can cause poor central vision. Fortunately, in the majority of circumstances cystoid macular oedema can be successfully treated.
Cystoid macular oedema causes decreased central vision, but thankfully does not affect the peripheral vision. It can result in blurred central vision and/or distorted central vision.
It occurs in about 1% of people who have undergone recent cataract surgery. In the overwhelming majority of these cases, there has been no technical problem with the surgery. In many cases, the condition will respond to the usual postoperative eye drop medications. A more effective treatment has been discovered which will cure cystoid macular oedema in the vast majority of cases. This consists of an injection of a steroid into the eye. The eye is numbed prior to the injection so that it does not feel anything.
Central serous retinopathy refers to a condition where there is a leakage of fluid into the central retina.
The symptoms associated with fluid accumulation within the retina can include the following – blurred vision, discoloured central vision, distorted central vision, smaller than normal image size.
The specific cause of central serous retinopathy is unknown. It is caused by a leakage of fluid from the layer under the retina such that fluid then accumulates within the retina. It is said to be more likely to occur during periods of emotional stress but this is not the total explanation for central serous retinopathy.
The doctor’s examination of the retina reveals a dome shaped accumulation of fluid within the retina. The appearance could be likened to a small “water blister” within the retina.
A fluorescein angiogram is often required to determine the specific leakage point within the retina.
Often the condition improves spontaneously. If it does not improve, then laser treatment and antiVEGF injection can be performed. The aim of the laser treatment is to stop the leakage of serous fluid from the abnormal leakage of the serous fluid into the retina.
The visual prognosis is usually very good. Rarely the condition can become disabling but 90% of the time vision will return to an almost normal level of vision.