What is Posterior Vitreous Detachment?
Posterior vitreous detachment (PVD) is a condition that often happens as people age. It involves the separation of a gel-like substance known as the vitreous, from the back part of the eye’s retina – the light-sensitive layer at the back of the eye. The idea of this condition was first introduced by Muller in 1856 and clinically by Briere in 1875, but a full understanding wasn’t reached until 1914.
The vitreous humor, a gel-like substance, sits between the clear, curved structure at the front of the eye (the lens) and the retina. It’s made mostly of water (98%), along with type 2 collagen and a substance called hyaluronic acid. It is housed within a clear membrane known as the hyaloid membrane. Early in life, the vitreous is firmly attached to the retina.
Posterior vitreous detachment is the most often seen reason for floats in your sight or field of vision. The floaters resemble small, spider-web-like forms and are a result of changes to the compact collagen matrix, a component of the posterior vitreous cortex, at the back of your eye. A sudden increase in the number of these floaters, along with the sudden experience of seeing flashes of light (known as photopsia), requires immediate attention from an eye care professional.
What Causes Posterior Vitreous Detachment?
Posterior vitreous detachment, or when the clear gel that fills the space at the back of your eye starts to pull away, is mostly due to age. When you’re young and healthy, this gel, otherwise known as vitreous, sticks to the back part of your eye’s interior. It sticks particularly strong in certain areas, including the margins of the optic disc, the macula, and around blood vessels.
As you age, the vitreous starts to change. Its gel-like consistency deteriorates in a process known as synchysis, and this causes the vitreous to become liquid. Parallelly, another process known as syneresis makes the fibrous parts of the gel stick together, leading to the vitreous collapsing. These parts float about in the vitreous and cause what we call “floaters” in the eye. Because of these changes, the gel’s grip on the retina weakens, and this may lead to posterior vitreous detachment.
Posterior vitreous detachment can happen on its own, but events like cataract surgery, physical eye trauma, inflammation, retina damage from laser treatment, and a type of laser eye surgery known as capsulotomy can also trigger it. In cases of sudden-onset posterior vitreous detachment, about 8%-22% of patients also have retinal tears at the time of their first examination. These tears usually happen at or just after symptoms start, and can be in varied shapes like U-shaped, operculated tears, or just holes in the retina. Surprisingly, 2-5% of the patients with acute posterior vitreous detachment, who didn’t have any tears initially, show retinal tears upon follow-up examinations.
Reports state that posterior vitreous detachment associated with bleeding from the posterior vitreous is more likely to result in retinal tears than without bleeding. In fact, 50-70% of patients with such complication have retinal tears, while only 7-12% of patients without bleeding have a retinal tear. And patients with acute posterior vitreous detachment and retinal tears are seven times more likely to have pigments or granules in the vitreous.
Some common risk factors of experiencing a posterior vitreous detachment include:
– Age: Posterior vitreous detachment occurrence jumps from 53% to 66% in the age group of 50 to 86 years, with 27% of eyes affected by the seventh decade of life and 63% affected by the eighth decade.
– Gender: Posterior vitreous detachment not only progresses faster in women than men aged over 60 years, but also translates into eye diseases connected to this condition happening sooner for women.
– Myopia: This can make you prone to posterior vitreous detachment, especially if your eyeball length is more than 30mm.
– Diseases like retinitis pigmentosa and Stickler syndrome can also make you more prone to posterior vitreous detachment.
– Menopause: Post-menopausal women may be more susceptible to this condition due to estrogen deficiency.
– Vitamin B6: Higher intake may increase the chance of this eye condition in women.
– Inflammation: Ongoing inflammation could lead to fibrosis in vitreous, causing the retina to be tugged and result in posterior vitreous detachments or retinal ruptures.
– Trauma and Ocular Surgery: Trauma to the eye and surgical interventions like cataract extraction, lens placement, LASIK can lead to modifications in the vitreous which can eventually cause posterior vitreous detachment. After one such operation, cataract surgery, visual changes like a higher viscosity of the vitreous near the retina and destabilized vitreous body were observed.
The gel in the vitreous has several angiogenic factors, which are essentially molecules that help form new blood vessels. This gel can act like a framework for new blood vessels to grow when still attached to the retina, but when completely detached, the process of neovascularization is prevented. This can help protect the eye from worsening of proliferative diabetic retinopathy, a severe eye disease related to diabetes.
Risk Factors and Frequency for Posterior Vitreous Detachment
There isn’t a lot of information available about how common posterior vitreous detachment is. However, studies carried out in hospitals and after death have suggested that age can play a big role in developing this condition.
Signs and Symptoms of Posterior Vitreous Detachment
Posterior vitreous detachment (PVD) often begins without any noticeable symptoms. It typically isn’t detected until the vitreous, a clear substance in the eye, separates from the margins of the optic disc, an area at the back of the eye. This separation can lead to symptoms such as:
- Flashes of light (photopsia), especially in the corner of the eye
- Specks or ‘floaters’ in your field of vision (myodesopsia)
- Blurry vision
Flashes of light usually occur suddenly and are more noticeable in low light. They can appear when moving the head or eyes. Floaters are small moving specks that are easily seen against a bright background. Bluriness can occur due to either the appearance of floaters or to bleeding in the vitreous.
If you experience any of these symptoms, you should have a complete retinal examination. This procedure should include a 360-degree examination of the ora serrata, an area at the front of the retina, and the use of a special microscope called a slit-lamp biomicroscope. The doctor would be looking for a detached posterior hyaloid membrane, a clear membrane located in the center of the vitreous. On examination, it might look like a crumpled translucent sheet.
One common sign of complete PVD is the appearance of the Weiss ring, which is a ring of tissue that appears in front of the optic disc. Additional signs like red cells or pigment granules, also known as Shafer sign or tobacco dust, can indicate possible retinal tears. Anyone showing these symptoms needs a thorough examination of the retina and should be referred to a specialist for further investigation.
An anomalous PVD (APVD) occurs when the vitreous humor, a gel-like substance in the eye, liquefies more than the separation between the vitreous and the retina (vitreoretinal dehiscence). The consequences of APVD depend on the location of the liquefaction:
- If it happens at the periphery of the retina, it can cause retinal tears.
- If it occurs at the macula, the central area of the retina, it can lead to vitreomacular traction, macular pucker, or macular hole.
- At the optic disc or the retina, it can result in vitreopapillary traction and plays a significant role in the formation of new blood vessels (neovascularization).
Testing for Posterior Vitreous Detachment
When doctors believe that a patient might be experiencing a condition known as acute posterior vitreous detachment, they usually resort to certain tests and procedures to confirm their suspicions. An important test in this process is known as binocular indirect ophthalmoscopy. Paired with three-mirror contact lens biomicroscopy, this can give doctors a detailed look into one’s eyes. Traditionally, B-scan ultrasonography (“an ultrasound for your eyes”) has been used for diagnosing this condition. Recently, an advanced diagnostic tool, optical coherence tomography (OCT), is being employed to precisely detect this condition.
Let’s talk about slit-lamp biomicroscopy. Before undergoing this test, the patients’ eyes would be dilated. Essentially, this test shines a bright light into eye for a closer look at various segments of the eye. The condition of posterior vitreous detachment can be, broadly speaking, of two types:
* Complete: where the separated eye tissue is free and can be easily traced to the base, and,
* Partial: some adherence is seen at or behind the middle of the eye.
Complete detachment can further breakdown into two subtypes:
* Collapsed: the eye tissue is loose, significantly detached, and easily visible.
* Without collapse: the eye tissue is slightly detached and can only be seen behind the retina.
The partial detachment can show signs such as minor shrinkage or sticking to the retina area.
Ultrasound, just as the traditional medical use, helps in providing a clear picture of what’s going inside your eye like confirming the extent of detachment.
Optical coherence tomography (OCT), a newer means of eye-check up, lights up the eye structures and results in a color-coded image. This makes understanding eye tissue morphology and thickness much simpler. OCT can detect shallow posterior vitreous detachment, something traditional methods might miss. OCT categorizes this condition into five stages, ranging from stage 0, where there is no detachment to stage 4, which is complete detachment.
In some cases, the OCT can show an attachment without abnormality before any noticeable changes appear, leading to a term known as a stage 0 macular hole. Ultimately, these tests and procedures help doctors construct a more accurate diagnosis, leading to better and more effective treatment plans.
Treatment Options for Posterior Vitreous Detachment
If you’re experiencing symptoms of a condition known as posterior vitreous detachment, including new floaters in your vision and without any vitreous hemorrhage (bleeding from your eye) or peripheral retinal breaks (tears in the edge of your retina), your eye doctor will likely want to see you again in 2-4 weeks. During this follow-up, they will perform a thorough examination of your retina. More often than not, patients reporting floaters will be managed conservatively. This means that your doctor will reassure you that over time, you’ll become less aware of the floaters or that the floaters might completely disappear. However, in some cases, the floaters may persist for six months to a year or more.
In some cases, posterior vitreous detachment may lead to mild bleeding in the eye, with the blood settling just in front of the part of your eye called the posterior pole. You may also notice some bleeding inside the retina, near the optic disc. If your eye doctor can’t examine your eye fully due to a vitreous hemorrhage, they may recommend that you stay in a propped-up position and rest, and may even suggest wearing an eye patch on both eyes. In these cases, you may also need an ultrasound scan of your eyes to check if there are any breaks in your retina or other issues.
When floaters are extreme, persist for a long time, and severely affect your quality of life, there are several treatment options available. One of these is vitrectomy, a type of eye surgery that involves removing and replacing the eye’s vitreous, or the clear gel-like substance that fills the inside of the eye. Although highly successful at reducing floaters and clearing your field of vision, vitrectomy does carry risks like the formation of cataracts, retinal detachment, and swelling in the macula, all of which can lead to permanent vision loss. Therefore, the pros and cons of the procedure should be carefully considered.
Another treatment option is Nd:YAG laser vitreolysis. This involves using an Nd:YAG laser to vaporize the floaters in the eye by raising the temperature to an extremely high level. The floaters are broken down into smaller, less noticeable pieces.
In certain cases, medications known as vitreolytic agents might be used. These drugs either dissolve the proteins causing the vitreous in the eye to stick to the retina, like ocriplasmin, or promote the liquefaction of the vitreous gel, ultimately separating it from the retina.
Treatment of posterior vitreous detachment when it is associated with retinal tears depends on the type of tear. If you have an “operculated” tear, whether it’s causing symptoms or not, you may not need treatment. However, some other types of tears, such as U-tears with persistent vitreous traction, can lead to a detached retina if untreated and, therefore, need prompt attention. For these cases, treatments are available, such as laser retinopexy and cryo-retinopexy. These procedures aim to create scarring around the tear in the retina to help it heal. After these procedures, patients are advised to rest and avoid vigorous exercises while the eye heals. Of the two, laser retinopexy is preferred because it is more precise, causes less damage to the retina, and has less risk of developing scar tissue. However, if you have a cloudy cornea or small pupils, cryotherapy might be a better option.
What else can Posterior Vitreous Detachment be?
Besides posterior vitreous detachment, Photopsia, a condition where you see flashes of light in your vision, can be caused by:
- A tear or detachment in the retina
- Classic migraine with aura
- Migraine headache without aura
- Posterior uveitis, which includes conditions like multiple evanescent white dot syndrome, acute idiopathic blind spot enlargement syndrome, acute zonal occult outer retinopathy, multifocal choroiditis and panuveitis, Birdshot retino-choroiditis
- Both the early and late stages of retinitis pigmentosa
As for floaters, or small specks or clouds moving in your field of vision, they can be caused by things other than posterior vitreous detachment, such as:
- Bleeding in the vitreous, the clear gel that fills the back of your eye, which can occur due to any cause including a tear or detachment in the retina or proliferative diabetic retinopathy
- Vitreous exudates in conditions like posterior uveitis and endophthalmitis
- Vitreous pigments
- Vitreous amyloidosis, a condition where abnormal proteins build up in your tissues and organs
- Intravitreal injection of drugs
What to expect with Posterior Vitreous Detachment
The outcome for simple posterior vitreous detachment, a condition where the back part of your eye’s gel-like substance peels away, is usually quite positive in terms of vision. However, the outcome for a complicated version of this condition (referred to as anomalous PVD) depends on its cause and any additional related complications.
Possible Complications When Diagnosed with Posterior Vitreous Detachment
When the vitreoretinal interface, which is the boundary between the retina and the vitreous gel in the eye, experiences abnormal pulling or tugging, it can lead to harmful effects on the retina and the vitreous. This pull can result in conditions like a macular pucker (wrinkling of the eye’s macula), a macular hole (small hole in the macula), or complicated proliferative diabetic vitreoretinopathy, a severe eye complication from diabetes.
Significant complications of posterior vitreous detachment, where the vitreous gel pulls away from the retina, include:
- Rips or tears in the retina
- Detached retina
- Bleeding in the vitreous gel
- Bleeding in the retina
- Swelling of the macula (cystoid macular edema)
- Holes in the macula
Preventing Posterior Vitreous Detachment
Patients should be given guidance based on how severe their condition is. If you’re dealing with mild floaters, which are small shapes that float in your field of vision, don’t worry too much. In most situations, these floaters settle down by themselves and become less noticeable over time. You should receive written instructions that highlight the importance of seeing your doctor again if you notice new symptoms, such as a sudden increase in floaters or flashes, loss of vision, or trouble seeing things out of the corners of your eyes.
