question: When you close your eyes, why do you sometimes see small, floating black spots?
comment: It’s actually the vitreous humor (jelly-like material inside your eye) clumped together. More common when looking at bright lights and/or if you are near sighted.
passages: Occasionally, uveitis is not associated with a systemic condition: the inflammation is confined to the eye and has unknown cause. In some of these cases, the presentation in the eye is characteristic of a described syndrome, which are called white dot syndromes, and include the following diagnoses:
  
  BULLET::::- acute posterior multifocal placoid pigment epitheliopathy
  
  BULLET::::- birdshot chorioretinopathy
  
  BULLET::::- multifocal choroiditis and panuveitis
  
  BULLET::::- multiple evanescent white dot syndrome
  
  BULLET::::- punctate inner choroiditis
  
  BULLET::::- serpiginous choroiditis
  
  BULLET::::- acute zonal occult outer retinopathy
  
  Section::::Causes.:Masquerade syndromes.
   Section::::Nature of white dots.:Suspected etiology.
  
  One cause of the White Dot Syndromes as suggested by Gass involves viral or infectious agents. Specifically pertaining to the ‘AZOOR complex,’ Gass has postulated that a virus may enter the retina at the optic head and the infection may spread from one photoreceptor to another. Some unexplained features include the development of more than one disease in the same patient and the majority of cases occurring in females.
   BULLET::::- very brief flashes of light (photopsia) in the extreme peripheral (outside of center) part of vision
  
  BULLET::::- a sudden dramatic increase in the number of floaters
  
  BULLET::::- 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:
  
  BULLET::::- a dense shadow that starts in the peripheral vision and slowly progresses towards the central vision
  
  BULLET::::- the impression that a veil or curtain was drawn over the field of vision
   There are various causes for the appearance of floaters, of which the most common are described here.
  
  Floaters can occur when eyes age; in rare cases, floaters may be a sign of retinal detachment or a retinal tear.
  
  Section::::Causes.:Vitreous syneresis.
   Most common:
  
  BULLET::::- Floaters, which are dark spots that float in the visual field
  
  BULLET::::- Blurred vision
  
  Intermediate uveitis normally only affects one eye. Less common is the presence of pain and photophobia.
  
  Section::::Signs and symptoms.:Posterior uveitis.
  
  Inflammation in the back of the eye is commonly characterized by:
  
  BULLET::::- Floaters
  
  BULLET::::- Blurred vision
  
  BULLET::::- Photopsia or seeing flashing lights
  
  Section::::Causes.
  
  Uveitis is usually an isolated illness, but can be associated with many other medical conditions.
   When this occurs there is a characteristic pattern of symptoms:
  
  BULLET::::- Flashes of light (photopsia)
  
  BULLET::::- A sudden dramatic increase in the number of floaters
  
  BULLET::::- 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.
   Patients with retinal tears may experience floaters if red blood cells are released from leaky blood vessels, and those with uveitis or vitritis, as in toxoplasmosis, may experience multiple floaters and decreased vision due to the accumulation of white blood cells in the vitreous humour.
  
  Other causes for floaters include cystoid macular edema and asteroid hyalosis. The latter is an anomaly of the vitreous humour, whereby calcium clumps attach themselves to the collagen network. The bodies that are formed in this way move slightly with eye movement, but then return to their fixed position.
  
  Section::::Diagnosis.
   Due to the large range of causes that lead to micropsia, diagnosis varies among cases. Computed tomography (CT) and magnetic resonance imaging (MRI) may find lesions and hypodense areas in the temporal and occipital lobes. MRI and CT techniques are able to rule out lesions as the cause for micropsia, but are not sufficient to diagnose the most common causes.
  
  Section::::Diagnosis.:Definition.
  
  Micropsia is the most common visual distortion, or dysmetropsia. It is categorized as an illusion in the positive phenomena grouping of abnormal visual distortions.
   The swampy area of Massachusetts known as the Bridgewater Triangle has folklore of ghostly orbs of light, and there have been modern observations of these ghost-lights in this area as well.
   Section::::Signs and symptoms.
  
  Patients with ARN typically present
  
  BULLET::::- floaters
  
  BULLET::::- redness of the eye
  
  BULLET::::- flashes
  
  BULLET::::- decreased sharpness of vision
  
  BULLET::::- photophobia.
   Serpiginous choroiditis, also known as geographic or helicoid choroidopathy, is an uncommon chronic progressive inflammatory condition affecting adult men and women equally in the second to seventh decades of life.
  
  Section::::Nature of white dots.
   The most common cause of floaters is shrinkage of the vitreous humour. This gel-like substance consists of 99% water and 1% solid elements. The solid portion consists of a network of collagen and hyaluronic acid, with the latter retaining water molecules. Depolymerization of this network makes the hyaluronic acid release its trapped water, thereby liquefying the gel. The collagen breaks down into fibrils, which ultimately are the floaters that plague the patient.
  
  Section::::Causes.:Vitreous detachments and retinal detachments.
   BULLET::::- Photophobia
  
  BULLET::::- Irregular pupil
  
  BULLET::::- Blacked out sclera
  
  BULLET::::- Headaches
  
  BULLET::::- Signs of anterior uveitis include dilated ciliary vessels, presence of cells and flare in the anterior chamber, and keratic precipitates ("KP") on the posterior surface of the cornea. In severe inflammation there may be evidence of a hypopyon. Old episodes of uveitis are identified by pigment deposits on lens, KPs, and festooned pupil on dilation of pupil.
  
  BULLET::::- "Busacca nodules", inflammatory nodules located on the surface of the iris in granulomatous forms of anterior uveitis such as Fuchs heterochromic iridocyclitis (FHI).
  
  BULLET::::- Synechia
  
  Section::::Signs and symptoms.:Intermediate uveitis.
   BULLET::::- A phosphene is the perception of light without light actually entering the eye, for instance caused by pressure applied to the closed eyes.
  
  A phenomenon that could be entoptical if the eyelashes are considered to be part of the eye is seeing light diffracted through the eyelashes. The phenomenon appears as one or more light disks crossed by dark blurry lines (the shadows of the lashes), each having fringes of spectral colour. The disk shape is given by the circular aperture of the pupil.
  
  Section::::See also.
  
  BULLET::::- Endaural phenomena
  
  BULLET::::- Floater
  
  BULLET::::- Form constant
  
  BULLET::::- Haidinger's brush
  
  BULLET::::- Hypnagogia
   Floaters present at birth usually remain lifelong, while those that appear later may disappear within weeks or months. They are not uncommon, and do not cause serious problems for most persons; they represent one of the most common presentations to hospital eye services. A survey of optometrists in 2002 suggested that an average of 14 patients per month per optometrist presented with symptoms of floaters in the UK. However, floaters are more than a nuisance and a distraction to those with severe cases, especially if the spots seem constantly to drift through the field of vision. The shapes are shadows projected onto the retina by tiny structures of protein or other cell debris discarded over the years and trapped in the vitreous humour. Floaters can even be seen when the eyes are closed on especially bright days, when sufficient light penetrates the eyelids to cast the shadows. It is not, however, only elderly persons who are troubled by floaters; they can also become a problem to younger people, especially if they are myopic. They are also common after cataract operations or after trauma.
   Brushfield spots
  
  Brushfield spots are small, white or grayish/brown spots on the periphery of the iris in the human eye due to aggregation of connective tissue, a normal constituent of the iris stroma. The spots are named after the physician Thomas Brushfield, who first described them in his 1924 M.D. thesis.
   Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) primarily occurs in adults (with a mean age of 27). Symptoms include blurred vision in both eyes, but the onset may occur at a different time in each eye. There are yellow-white placoid lesions in the posterior pole at the level of the RPE. Some suggest a genetic predisposition to the disease, while others postulate an abnormal immune response to a virus.
  
  Section::::Specific white dot syndromes.:Multiple evanescent white dot syndrome.
   BULLET::::- Multifocal choroiditis and panuveitis (MCP)
  
  BULLET::::- Punctate inner choroiditis (PIC)
  
  BULLET::::- Serpiginous choroiditis
  
  Section::::Specific white dot syndromes.
  
  Specific characteristics regarding the white dots and predicted etiology are presented of selected diseases.
  
  Section::::Specific white dot syndromes.:Acute Posterior Multifocal Placoid Pigment Epitheliopathy.
   The presence of retinal tears with new onset of floaters was surprisingly high (14%; 95% confidence interval, 12–16%) as reported in a meta-analysis published as part of the Rational Clinical Examination Series in the Journal of the American Medical Association. Patients with new onset flashes and/or floaters, especially when associated with visual loss or restriction in the visual field, should seek more urgent ophthalmologic evaluation.
  
  Section::::Treatment.
   Floaters are visible because of the shadows they cast on the retina or refraction of the light that passes through them, and can appear alone or together with several others in one's visual field. They may appear as spots, threads, or fragments of cobwebs, which float slowly before the observer's eyes, and move especially in the direction in which the eyes move. As these objects exist within the eye itself, they are not optical illusions but are entoptic phenomena. They are not to be confused with visual snow, although these two conditions may co-exist.
  
  Section::::Signs and symptoms.
   • The appearance of gray-white or yellow punctate (punched out) areas (lesions) at the level of the inner choroid. These lesions are typically located centrally at the back of the eye (posterior pole).
  
  Symptoms typically include:
  
  BULLET::::1. Blurring of vision
  
  BULLET::::2. Partial ‘blind spots’ or scotoma. These areas of diminished or lost areas of the visual field are typically near the centre of vision but occasionally can be peripheral. These may be temporary or permanent.
  
  BULLET::::3. Seeing flashing lights. This is known as photopsia.
   The most frequent neurological origin of micropsia is a result of temporal lobe seizures. These seizures affect the entire visual field of the patient. More rarely, micropsia can be part of purely visual seizures. This in turn only affects one half of the visual field and is accompanied by other cerebral visual disturbances. The most common cause of seizures which produce perceptual disturbances such as micropsia and macropsia is medial temporal lobe epilepsy in which the seizures originate in the amygdala-hippocampus complex. Micropsia often occurs as an aura signalling a seizure in patients with medial temporal lobe epilepsy. Most auras last for a very short period, ranging from a few seconds to a few minutes.
   Florida keratopathy appears as multiple cloudy opacities in the stromal layer of the cornea. The spots appear concentrated at the center and become more diffuse at the periphery. They can range in size from one to eight millimeters. There are no other symptoms, and there is no response to treatment with either anti-inflammatory or antimicrobial drugs. Histological analysis of affected corneas has found acid-fast staining organisms, suggesting Florida keratopathy may be caused by a type of mycobacterium. The disease may be induced by repeated stings to the eyes by the little fire ant, "Wasmannia auropunctata".
   BULLET::::- Seizures, often preceded by hallucinations of disagreeable odors, often originate in the uncus.
   BULLET::::- Floaters or "muscae volitantes" are slowly drifting blobs of varying size, shape, and transparency, which are particularly noticeable when viewing a bright, featureless background (such as the sky) or a point source of diffuse light very close to the eye. They are all shadow images of objects suspended just above the retina. Some may be individual red blood cells swollen due to osmotic pressure. Others may be chains of red blood cells stuck together; diffraction patterns can be seen around these. They may also be "coagula of the proteins of the vitreous gel, to embryonic remnants, or the condensation round the walls of Cloquet's canal". The first two sort of floaters do float in liquid between the vitreous and the retina, so they may collect over the fovea (the center of vision), and therefore be more visible, when a person is lying on his or her back looking upwards.
  