question: why does one eye sometimes have a warm tint while the other has a cool tint?
comment: There's two ways of interpreting your question: **Why can the view from one eye have a different tint than the other?** Your eyes can have a different number and distribution of red, green, and blue cone cells that sense color. Normally, with two eyes, the differences average out but looking with one and then the other, the differences will stand out. Also, if you close one eye for a long time, it becomes more sensitive to blue because your eyelid blocks most light besides red. This acts like colored sunglasses so your brain/eye compensates by sensing more blue. When you switch eyes, the one that was closed will have a cooler tint for a short period of time. **Why do some people's eye color have different tints?** Depending on the angle, a person's iris can reflect a different band of colors. This causes some people's eye color to change depending on the angle you look at their eyes. Also, one eye could be exposed to more light than the other (especially if the nose is in the way). This can make one eye color appear cooler or warmer than the other.
passages: The predominant optical aberration of the eye in keratoconus is coma. The visual distortion experienced by the person comes from two sources, one being the irregular deformation of the surface of the cornea, and the other being scarring that occurs on its exposed highpoints. These factors act to form regions on the cornea that map an image to different locations on the retina. The effect can worsen in low light conditions, as the dark-adapted pupil dilates to expose more of the irregular surface of the cornea.
  
  Section::::Genetics.
   Section::::Prognosis.:Corneal hydrops.
  
  In advanced cases, bulging of the cornea can result in a localized rupture of Descemet's membrane, an inner layer of the cornea. Aqueous humor from the eye's anterior chamber seeps into the cornea before Descemet's membrane reseals. The patient experiences pain and a sudden severe clouding of vision, with the cornea taking on a translucent milky-white appearance known as a corneal hydrops.
   Section::::Professional career.:New York Giants.:Detached retina.
   Sometimes there is flushing on the affected side of the face due to dilation of blood vessels under the skin. The pupil's light reflex is maintained as this is controlled via the parasympathetic nervous system.
  
  In children, Horner's syndrome sometimes leads to heterochromia, a difference in eye color between the two eyes. This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris.
  
  In veterinary medicine, signs can include partial closure of the third eyelid, or nictitating membrane.
  
  Section::::Causes.
   Another hypothesis about heterochromia is that it can result from a viral infection "in utero" affecting the development of one eye, possibly through some sort of genetic mutation. Occasionally, heterochromia can be a sign of a serious medical condition.
  
  A common cause in females with heterochromia is X-inactivation, which can result in a number of heterochromatic traits, such as calico cats. Trauma and certain medications, such as some prostaglandin analogues, can also cause increased pigmentation in one eye. On occasion, a difference in eye color is caused by blood staining the iris after injury.
   If there is an afferent defect in the left eye, both pupils will dilate when the light is shining on the left eye, but both will constrict when it is shining on the right eye. This is because the left eye will not respond to external stimulus (afferent pathway), but can still receive neural signals from the brain (efferent pathway) to constrict.
  
  If there is a unilateral small pupil with normal reactivity to light, it is unlikely that a neuropathy is present.
  
  However, if accompanied by ptosis of the upper eyelid, this may indicate Horner's syndrome.
   Section::::Symptoms.
  
  Symptoms of entropion include:
  
  BULLET::::- Redness and pain around the eye
  
  BULLET::::- Sensitivity to light and wind
  
  BULLET::::- Sagging skin around the eye
  
  BULLET::::- Epiphora
  
  BULLET::::- Decreased vision, especially if the cornea is damaged
  
  Section::::Causes.
  
  BULLET::::- Congenital
  
  BULLET::::- Aging creating loose skin and stretched and loose ligaments and muscles (senile entropion).
  
  BULLET::::- Scarring (mechanical entropion)
  
  BULLET::::- Spasm
  
  BULLET::::- An eye infection called trachoma is still common in North Africa and South Asia and this can cause scarring of the inner eyelid, which may cause friction and entropion.
  
  Section::::Treatment.
   Section::::Eyeshine and red-eye effect.
  
  In flash photographs, odd-eyed cats typically show a red-eye effect in the blue eye, but not in the other eye. This is due to the combined effect of the (normal) presence of a tapetum lucidum in both eyes and the absence of melanin in the blue eye. The tapetum lucidum produces eyeshine in both eyes, but in the non-blue eye a layer of melanin over the tapetum lucidum selectively removes some colors of light.
   Genetic variation in humans, as for the purposes of this section, will refer to any variance in phenotype which results from heritable allele expression, mutations, and epigenetic changes. While human phenotypes may seem diverse, individuals actually differ by only 1 in every 1,000 genes and is primarily the result of inherited genetic differences. Pure consideration of alleles is often referred to as Mendelian Genetics, or more properly Classical Genetics, and involves the assessment of whether a given trait is dominant or recessive and thus, at what rates it will be inherited.  The color of one's eyes was long believed to occur with a pattern of brown-eye dominance, with blue eyes being a recessive characteristic resulting from a past mutation. However, it is now understood that eye color is controlled by various genes, and thus, may not follow as distinct a pattern as previously believed. The trait is still the result of variance in genetic sequence between individuals as a result of inheritance from their parents. Common traits which may be linked to genetic patterns are earlobe attachment, hair color, and hair growth patterns.
   Section::::Visual system.
  
  Section::::Visual system.:Multiple retinas.
   Section::::Blue irises.
   Such vascularization is likely to result in blurring of vision secondary to corneal stromal scarring, the presence of ghost vessels, and thinning of the cornea, especially if it involves the visual axis.
  
  Section::::Cause.
   To maintain stereopsis and singleness of vision, the eyes need to be pointed accurately. The position of each eye in its orbit is controlled by six extraocular muscles. Slight differences in the length or insertion position or strength of the same muscles in the two eyes can lead to a tendency for one eye to drift to a different position in its orbit from the other, especially when one is tired. This is known as phoria. One way to reveal it is with the cover-uncover test. To do this test, look at a cooperative person's eyes. Cover one eye of that person with a card. Have the person look at your finger tip. Move the finger around; this is to break the reflex that normally holds a covered eye in the correct vergence position. Hold your finger steady and then uncover the person's eye. Look at the uncovered eye. You may see it flick quickly from being wall-eyed or cross-eyed to its correct position. If the uncovered eye moved from out to in, the person has esophoria. If it moved from in to out, the person has exophoria. If the eye did not move at all, the person has orthophoria. Most people have some amount of exophoria or esophoria; it is quite normal. If the uncovered eye also moved vertically, the person has hyperphoria (if the eye moved from down to up) or hypophoria (if the eye moved from up to down). Such vertical phorias are quite rare. It is also possible for the covered eye to rotate in its orbit. Such cyclophorias cannot be seen with the cover-uncover test; they are rarer than vertical phorias.
   Although a distinction is frequently made between heterochromia that affects an eye completely or only partially (sectoral heterochromia), it is often classified as either genetic (due to mosaicism or congenital) or acquired, with mention as to whether the affected iris or portion of the iris is darker or lighter. Most cases of heterochromia are hereditary, and are entirely benign and unconnected to any pathology, however, some are associated with certain diseases and syndromes. Sometimes one eye may change color following disease or injury.
  
  Section::::Classification.:Sectoral or partial heterochromia.
   Anhidrosis (lack of sweating) is a common symptom, and less commonly hyperhidrosis (excessive sweating).
  
  Additionally, patients can exhibit Raynaud's disease-like symptoms with neuropathy (in particular, burning extremity pain).
  
  Ocular involvement may be present showing cornea verticillata (also known as vortex keratopathy), i.e. clouding of the corneas. Keratopathy may be the presenting feature in asymptomatic patients, and must be differentiated from other causes of vortex keratopathy (e.g. drug deposition in the cornea). This clouding does not affect vision.
  
  Other ocular findings can include conjunctival and retinal vascular abnormalities and anterior/posterior spoke-like cataract. Visual reduction from these manifestations is uncommon.
   Opacities may be keratic, that is, due to the deposition of inflammatory cells, hazy, usually from corneal edema, or they may be localized in the case of corneal ulcer or keratitis.
  
  Corneal epithelial disruptions may be detected with fluorescein staining of the eye, and careful observation with cobalt-blue light.
  
  Corneal epithelial disruptions would stain green, which represents some injury of the corneal epithelium.
  
  These types of disruptions may be due to corneal inflammations or physical trauma to the cornea, such as a foreign body.
  
  Section::::Diagnosis.:Pupillary abnormalities.
   Section::::Related disorders.
  
  Several other corneal ectatic disorders also cause thinning of the cornea:
  
  BULLET::::- Keratoglobus is a very rare condition that causes corneal thinning primarily at the margins, resulting in a spherical, slightly enlarged eye. It may be genetically related to keratoconus.
  
  BULLET::::- Pellucid marginal degeneration causes thinning of a narrow (1–2 mm) band of the cornea, usually along the inferior corneal margin. It causes irregular astigmatism that, in the early stages of the disease can be corrected by spectacles. Differential diagnosis may be made by slit-lamp examination.
   A doctor examining an eye with retinopathy may be able to see no signs at all, or a slight macular edema, which is a sort of blister on or under the macula, an oval colored spot normally visible to an eye doctor on each person's retina.
  
  But while even that edema goes away, within a few days the patient will generally develop a discoloration of the retina at the injured point, often yellow or white, turning red over the next few weeks.
  
  Section::::Treatment.
   In contrast, fixation disparity is a very small deviation of the pointing directions of the eyes that is present while performing binocular fusion.
  
  Heterophoria is usually asymptomatic. This is when it is said to be "compensated". When fusional reserve is used to compensate for heterophoria, it is known as compensating vergence. In severe cases, when the heterophoria is not overcome by fusional vergence, sign and symptoms appear. This is called decompensated heterophoria.
  
  Heterophoria may lead to squint, also known as strabismus.
  
  Section::::Signs and symptoms.
   If both eyes are affected by PION, the pupils may look symmetrical. However, if the eyes are asymmetrically affected, i.e. one eye's optic nerve is more damaged than the other, it will produce an important sign called an afferent pupillary defect.
  
  Defective light perception in one eye causes an asymmetrical pupillary constriction reflex called the afferent pupillary defect (APD).
  
  Section::::Signs and symptoms.:Arteritic PION.
   Short-Tempered Melancholic
  
  Section::::Reception.
   Section::::Eye color.:Different colors in the two eyes.
   Section::::Genotypes.
  
  TE1/TE1 or TE1/TE2: Yellow, amber, or bright orange eyes.br
  
  TE2/TE2: Blue eyes when in combination with cream. It is not known what this looks like without cream. Only one horse has been tested to carry this genotype.br
  
  TE1/n, TE2/n, or n/n: Dark eyes.
  
  Section::::Molecular Genetics.
   Keratoconus is normally bilateral (affecting both eyes) although the distortion is usually asymmetric and is rarely completely identical in both corneas. Unilateral cases tend to be uncommon, and may in fact be very rare if a very mild condition in the better eye is simply below the limit of clinical detection. It is common for keratoconus to be diagnosed first in one eye and not until later in the other. As the condition then progresses in both eyes, the vision in the earlier-diagnosed eye will often remain poorer than that in its fellow.
  
  Section::::History.
   The main characteristic that distinguishes physiological anisocoria is an increase of pupil size with lower light or reduced illumination, such that the pupils differ in size between the two eyes. At any given eye examination, up to 41% of healthy patients can show an anisocoria of 0.4 mm or more at one time or another. It can also occur as the difference between both pupils varies from day to day. A normal population survey showed that during poor light or near dark conditions, differences of 1 mm on average between pupils was found. 
  