Vitreous hemorrhage is the extravasation, or leakage, of blood into the areas in and around the vitreous humor of the eye. The vitreous humor is the clear gel that fills the space between the lens and the retina of the eye. A variety of conditions can result in blood leaking into the vitreous humor, which can cause impaired vision, floaters, and photopsia.

The most common cause found in adults is diabetic retinopathy. Abnormal blood vessels can form in the back of the eye of a person with diabetes. These new blood vessels are weaker and prone to breaking and causing hemorrhage. Diabetic retinopathy accounts for 31.5-54% of all cases of vitreous hemorrhage in adults in the United States.

Patients with BRVO usually complain of sudden onset of blurred vision or a central visual field defect.

The eye examination findings of acute BRVO include superficial hemorrhages, retinal edema, and often cotton-wool spots in a sector of retina drained by the affected vein.The obstructed vein is dilated and tortuous.

The quadrant most commonly affected is the superotemporal (63%).

Retinal neovascularization occurs in 20% of cases within the first 6–12 months of occlusion and depends on the area of retinal nonperfusion. Neovascularization is more likely to occur if more than five disc diameters of nonperfusion are present and vitreous hemorrhage can ensue.

Ocular causes include:

- Iritis

- Keratitis

- Blepharitis

- Optic disc drusen

- Posterior vitreous detachment

- Closed-angle glaucoma

- Transient elevation of intraocular pressure

- Intraocular hemorrhage

- Coloboma

- Myopia

- Orbital hemangioma

- Orbital osteoma

- Keratoconjunctivitis sicca

When this occurs there is a characteristic pattern of symptoms:

- Flashes of light (photopsia)

- A sudden dramatic increase in the number of floaters

- A ring of floaters or hairs just to the temporal side of the central vision

As a posterior vitreous detachment proceeds, adherent vitreous membrane may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with resultant flashes that can look like a perfect circle.

If a retinal vessel is torn, the leakage of blood into the vitreous cavity is often perceived as a "shower" of floaters. Retinal vessels may tear in association with a retinal tear, or occasionally without the retina being torn.

The experience of amaurosis fugax is classically described as a temporary loss of vision in one or both eyes that appears as a black "curtain coming down vertically into the field of vision in one eye;" however, this altitudinal visual loss is relatively uncommon. In one study, only 23.8 percent of patients with transient monocular vision loss experienced the classic "curtain" or "shade" descending over their vision. Other descriptions of this experience include a monocular blindness, dimming, fogging, or blurring. Total or sectorial vision loss typically lasts only a few seconds, but may last minutes or even hours. Duration depends on the cause of the vision loss. Obscured vision due to papilledema may last only seconds, while a severely atherosclerotic carotid artery may be associated with a duration of one to ten minutes. Certainly, additional symptoms may be present with the amaurosis fugax, and those findings will depend on the cause of the transient monocular vision loss.

Retinal hemorrhage is a disorder of the eye in which bleeding occurs into the light sensitive tissue on the back wall of the eye. A retinal hemorrhage can be caused by hypertension, retinal vein occlusion (a blockage of a retinal vein), or diabetes mellitus (which causes small fragile blood vessels to form, which are easily damaged). Retinal hemorrhages can also occur due to shaking, particularly in young infants (shaken baby syndrome) or from severe blows to the head.

Retinal hemorrhages that take place outside the macula can go undetected for many years, and may sometimes only be picked up when the eye is examined in detail by ophthalmoscopy, fundus photography, or a dilated fundus exam. However, some retinal hemorrhages can cause severe impairment of vision. They may occur in connection with posterior vitreous detachment or retinal detachment.

Branch retinal vein occlusion (BRVO) is a common retinal vascular disease of the elderly. It is caused by the occlusion of one of the branches of central retinal vein.

The risk of retinal detachment is greatest in the first 6 weeks following a vitreous detachment, but can occur over 3 months after the event.

The risk of retinal tears and detachment associated with vitreous detachment is higher in patients with myopic retinal degeneration, lattice degeneration, and a familial or personal history of previous retinal tears/detachment.

Patients are often asymptomatic in the initial stages of retinal perivasculitis. Some patients may develop symptoms such as floaters, blurring vision, or even gross diminution of vision due to massive vitreous hemorrhage. Vision in these patients can be normal to hand movements or light perception only. Bilaterality is quite common (50–90%) patients.

A rhegmatogenous retinal detachment is commonly preceded by a posterior vitreous detachment which gives rise to these symptoms:

- flashes of light (photopsia) – very brief in the extreme peripheral (outside of center) part of vision

- a sudden dramatic increase in the number of floaters

- a ring of floaters or hairs just to the temporal (skull) side of the central vision

Although most posterior vitreous detachments do not progress to retinal detachments, those that do produce the following symptoms:

- a dense shadow that starts in the peripheral vision and slowly progresses towards the central vision

- the impression that a veil or curtain was drawn over the field of vision

- straight lines (scale, edge of the wall, road, etc.) that suddenly appear curved (positive Amsler grid test)

- central visual loss

In the event of an appearance of sudden flashes of light or floaters, an eye doctor needs to be consulted immediately. A shower of floaters or any loss of vision, too, is a medical emergency.

Retinal haemorrhages commonly occur in high attitude climbers, most likely due to the effects of systemic hypoxia on the eye. Risk is correlated with the maximum altitude reached, duration of exposure to high altitude conditions, and climb rate.

Patients with idiopathic macular telangiectasia type 1 are typically 40 years of age or older. They may have a coincident history of ischemic vascular diseases such as diabetes or hypertension, but these do not appear to be causative factors.

Macular telangiectasia type 2 usually present first between the ages of 50 and 60 years, with a mean age of 55–59 years. They may present with a wide range of visual impact, from totally asymptomatic to substantially impaired; in most cases however, patients retain functional acuity of 20/200 or better. Metamorphopsia may be a subjective complaint. Due to the development of paracentral scotomota (blind spots), reading ability is impaired early in the disease course. It might be even the first symptom of the disease.

The condition may remain stable for extended periods, sometimes interspersed with sudden decreases in vision. Patients’ loss of visual function is disproportionately worse than the impairment of their visual acuity, which is only mildly affected in many cases. In patients with MacTel, as compared with a reference population, there is a significantly higher prevalence of systemic conditions associated with vascular disease, including history of hypertension, history of diabetes, and history of coronary disease. MacTel does not cause total blindness, yet it commonly causes gradual loss of the central vision required for reading and driving.

The most common sign at presentation is leukocoria (abnormal white reflection of the retina). Symptoms typically begin as blurred vision, usually pronounced when one eye is closed (due to the unilateral nature of the disease). Often the unaffected eye will compensate for the loss of vision in the other eye; however, this results in some loss of depth perception and parallax. Deterioration of sight may begin in either the central or peripheral vision. Deterioration is likely to begin in the upper part of the vision field as this corresponds with the bottom of the eye where blood usually pools. Flashes of light, known as photopsia, and floaters are common symptoms. Persistent color patterns may also be perceived in the affected eye. Initially, these may be mistaken for psychological hallucinations, but are actually the result of both retinal detachment and foreign fluids mechanically interacting with the photoreceptors located on the retina.

One early warning sign of Coats' disease is yellow-eye in flash photography. Just as the red-eye effect is caused by a reflection off blood vessels in the back of a normal eye, an eye affected by Coats' will glow yellow in photographs as light reflects off cholesterol deposits. Children with yellow-eye in photographs are typically advised to immediately seek evaluation from an optometrist or ophthalmologist, who will assess and diagnose the condition and refer to a vitreo-retinal specialist.

Coats' disease itself is painless. Pain may occur if fluid is unable to drain from the eye properly, causing the internal pressure to swell, resulting in painful glaucoma.

Hypopyon is a medical condition involving inflammatory cells in the anterior chamber of the eye.

It is a leukocytic exudate, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera. It is a sign of inflammation of the anterior uvea and iris, i.e. iritis, which is a form of anterior uveitis. The exudate settles at the dependent aspect of the eye due to gravity. It can be sterile (in bacterial corneal ulcer) or not sterile (fungal corneal ulcer).

Patients with ARN typically present

- floaters

- redness of the eye

- flashes

- decreased sharpness of vision

- photophobia.

Though uncommon, some patients may experience pain. Most patients will only experience this in one eye (unilateral), though possible for the condition to be seen in both (bilateral, BARN). If the first eye is left without treatment, some cases have shown the disease progressing to the other eye in a month's time. Further progressed stages of the disease can cause blindness in the eye experiencing ARN. Though the disease may be present itself, the inflammation of the retina may not been visualized for decades after the initial signs.

"Typical lattice" consists of sharply demarcated, spindle-shaped areas of retinal thinning, usually located between the equator of the retina and the posterior border of the vitreous base. This is more frequently located in the temporal half of the retina and is seen more superiorly than inferiorly.

"Atypical lattice" is characterised by radial lesions which appear continuous with the peripheral blood vessels. This type is typically seen in patients with Stickler syndrome.

Clinical signs include redness of the eye, pain, blurring of vision, photophobia and floaters.

Vitreomacular adhesion (VMA) is a human medical condition where the vitreous gel (or simply vitreous) of the human eye adheres to the retina in an abnormally strong manner. As the eye ages, it is common for the vitreous to separate from the retina. But if this separation is not complete, i.e. there is still an adhesion, this can create pulling forces on the retina that may result in subsequent loss or distortion of vision. The adhesion in of itself is not dangerous, but the resulting pathological vitreomacular traction (VMT) can cause severe ocular damage.

The current standard of care for treating these adhesions is pars plana vitrectomy (PPV), which involves surgically removing the vitreous from the eye. A biological agent for non-invasive treatment of adhesions called ocriplasmin has been approved by the FDA on Oct 17 2012.

Central serous retinopathy (CSR), also known as central serous chorioretinopathy (CSC or CSCR), is an eye disease which causes visual impairment, often temporary, usually in one eye. When the disorder is active it is characterized by leakage of fluid under the retina that has a propensity to accumulate under the central macula. This results in blurred or distorted vision (metamorphopsia). A blurred or gray spot in the central visual field is common when the retina is detached. Reduced visual acuity may persist after the fluid has disappeared.

The disease is considered of unknown cause. It mostly affects white males in the age group 20 to 50 and occasionally other groups. The condition is believed to be exacerbated by stress or corticosteroid use.

Traction caused by VMA is the underlying pathology of an eye disease called symptomatic VMA. There is evidence that symptomatic VMA can contribute to the development of several well-known eye disorders, such as macular hole and macular pucker, that can cause visual impairment, including blindness. It may also be associated with age-related macular degeneration (AMD), diabetic macular edema (DME), retinal vein occlusion, and diabetic retinopathy (DR).

Intermediate uveitis is a form of uveitis localized to the vitreous and peripheral retina. Primary sites of inflammation include the vitreous of which other such entities as pars planitis, posterior cyclitis, and hyalitis are encompassed. Intermediate uveitis may either be an isolated eye disease or associated with the development of a systemic disease such as multiple sclerosis or sarcoidosis. As such, intermediate uveitis may be the first expression of a systemic condition. Infectious causes of intermediate uveitis include Epstein-Barr virus infection, Lyme disease, HTLV-1 virus infection, cat scratch disease, and hepatitis C.

Permanent loss of vision is most commonly seen in patients with chronic cystoid macular edema (CME). Every effort must be made to eradicate CME when present. Other less common causes of visual loss include retinal detachment, glaucoma, band keratopathy, cataract, vitreous hemorrhage, epiretinal membrane and choroidal neovascularization.

Coats' usually affects only one eye (unilateral) and occurs predominantly in young males 1/100,000, with the onset of symptoms generally appearing in the first decade of life. Peak age of onset is between 6–8 years of age, but onset can range from 5 months to 71 years.

Coats' disease results in a gradual loss of vision. Blood leaks from the abnormal vessels into the back of the eye, leaving behind cholesterol deposits and damaging the retina. Coats' disease normally progresses slowly. At advanced stages, retinal detachment is likely to occur. Glaucoma, atrophy, and cataracts can also develop secondary to Coats' disease. In some cases, removal of the eye may be necessary (enucleation).

It is characterized by three overlapping stages of venous inflammation (vasculitis), occlusion, and retinal neovascularization.

Lattice degeneration is a disease of the human eye wherein the peripheral retina becomes atrophic in a lattice pattern and may develop tears, breaks, or holes, which may further progress to retinal detachment. It is an important cause of retinal detachment in young myopic individuals. The cause is unknown, but pathology reveals inadequate blood flow resulting in ischemia and fibrosis.

Lattice degeneration occurs in approximately 6–8% of the general population and in approximately 30% of phakic retinal detachments. Similar lesions are seen in patients with Ehlers-Danlos syndrome, Marfan syndrome, and Stickler syndrome, all of which are associated with an increased risk of retinal detachment. Risk of developing lattice degeneration in one eye is also increased if lattice degeneration is already present in the other eye.