Vitreo Retinal Conditions
Flashes and Floaters and retinal tears
The vitreous gel inside the eye changes in consistency as we get older and most people note grey floaters in their vision often from their 20’s. This occurs because solid filaments of gel move around in a more liquid matrix and, in bright lighting conditions, cast shadows back on the retina. These floaters are rarely concerning, and the brain is very adept at filtering this ‘junk information’ so that we don’t see them all the time.
As we get older, the gel changes further in consistency and starts to separate away from the retina in a process known as posterior vitreous detachment (PVD). Patients frequently report a grey circle in their vision, or ‘frog spawn’ or a ‘spiders web’ appearing. This is sometimes accompanied by flashes of light which represents traction from the gel on the retina. This can be alarming for patients and if it happens acutely, you should probably have this looked at.
If there is a further acute onset of black floaters, this may be a retinal tear. This occurs when the gel is too firmly adherent to the peripheral retina and pulls on it causing a tear to form. This can lead to a retinal detachment and should be seen urgently for treatment with either laser or cryotherapy to weld the retina shut to prevent detachment.
The retina is the photosensitive film at the back of the eye that turns light into electrical signals that are carried to the brain to allow us to see. The retina can become detached from the wall of the eye. There are a number of different causes.
Retinal detachment describes an emergency situation in which a thin layer of tissue (the retina) at the back of the eye pulls away from the layer of blood vessels that provides it with oxygen and nutrients. Retinal detachment is often accompanied by flashes and floaters in your vision
If only a small part of your retina has detached, you may not have any symptoms.
But if more of your retina is detached, you may not be able to see as clearly as normal, and you may notice other sudden symptoms, including:
• A lot of new floaters (small dark spots or squiggly lines that float across your vision)
• Flashes of light in one eye or both eyes
• A dark shadow or “curtain” on the sides or in the middle of your field of vision
If the retinal detachment involves the centre of the vision (the macula) then the quality of the vision will usually be permanently damaged. It is important therefore important to try to operate on a retinal detachment before the macular becomes detached. If the macula is off, surgery will still be performed and much vision recovered but it less imperative that it is performed on an emergency basis.
There are a number of surgical approaches and the technique used will depend on both surgical preference, age of patient, and the exact type of retinal detachment.
A macular hole is a rare eye condition that can blur the central vision you use to do everyday tasks like driving or reading. The macula is a small area in the center of the retina (the light-sensitive layer of tissue in the back of the eye)
There are primary and secondary macular holes. A primary macular hole is one that develops without any eye injury and isn’t due to another medical condition. A secondary macular hole is a macular hole that occurs with or due to another disease or condition such as trauma or eye inflammation (uveitis).
It is usually caused by abnormal adhesions between the jelly of the eye (vitreous) and the retina. As we get older, the vitreous frequently separates away from the retina in a process known as posterior vitreous detachment (PVD). In some cases however the vitreous is firmly stuck to the retina and traction from the gel pulls a hole. Patients frequently complain of difficulty with reading or seeing faces and there is often distortion at the centre of the vision.
The early symptoms of a macular hole include:
• Blurred vision
• Distorted vision. Straight lines might be curvy or wavy.
• Difficulty reading small print.
A later sign of a macular hole is a dark or blind spot in the center of your vision. This hole can be closed with surgery. Your surgeon will perform a vitrectomy (removal of the vitreous); a thin membrane on the surface of the retina is then peeled off (ILM peel); and the eye is then filled with gas.
You may be asked to “posture” after surgery: this involves looking or lying face down so that the gas bubble is in contact with the hole. This may be for a number of days. Not all surgeons advocate this however.
The vision will take some time to recover and is unlikely to be quite as good as it used to be. The distortion is usually much improved and there is more central detail than preoperatively.
An epiretinal membrane (also known as macular pucker, or cellophane maculopathy) is a layer of scar tissue that forms over the centre of the retina at the macula. This acts like all scar tissue does – which means that it contracts. This pulls the underlying retina into folds causing thickening and distortion of the retinal architecture. This in turn can cause distortion of a patient’s vision and blur.
Most patients with ERMs have no symptoms; their ERMs are found incidentally on dilated retinal exam or on retinal imaging such as with ocular coherence tomography (OCT). In such cases, patients typically have normal or near-normal vision. However, ERMs can slowly progress, leading to a vague visual distortion that can be perceived better by closing the non- or less-affected eye.
Patients may notice metamorphopsia, a symptom that causes visual distortion in which shapes that are normally straight, like window blinds or a door frame, looking “wavy” or “crooked,” especially when compared to the other eye. In advanced cases, this can lead to severely decreased vision. Less commonly, ERMs may also be associated with double vision, light sensitivity or images looking larger or smaller than they actually are.
Treatment is most commonly with surgery. Your surgeon will perform a vitrectomy – to remove the vitreous gel of the eye. The epiretinal membrane is then stained with a special dye. It can then be peeled off the surface of the retina.
The vision takes some time to recover; it can sometimes get transiently worse post operatively, as removal of the membrane causes inflammation and thickening of the retina (rather as the skin becomes red and swollen after removal of a sticky plaster). Over several months, however, the retinal architecture improves and the quality of vision with it.
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