Experiencing yellow spots or other visual disturbances can be unsettling. These visual phenomena range from harmless, temporary effects caused by external stimuli to symptoms of underlying conditions affecting the eye or nervous system. This article explores the common explanations for seeing yellow spots, differentiating between transient visual events and more persistent changes. While most causes are not immediate emergencies, any change in vision warrants evaluation by an eye care professional.
Temporary Visual Stress and Afterimages
The brief perception of a yellow spot that quickly fades is often a normal physiological reaction to intense light exposure. This phenomenon is known as an afterimage, occurring when photoreceptor cells in the retina become temporarily overstimulated or “bleached.” Staring at a bright source, such as a camera flash or a reflective surface in sunlight, saturates the photopigments within these light-sensing cells. When you look away, the saturated cells continue sending a signal to the brain, creating a temporary spot. The color of the afterimage is often the complementary color of the original light, but bright stimuli can also leave a direct image that appears yellow or white.
These transient spots can also be a type of phosphene, which is the perception of light without actual light entering the eye. Phosphenes are sometimes induced by mechanical pressure, such as rubbing the eyelids. The physical stimulation “tricks” the retinal cells into firing an electrical signal, which the brain interprets as a spot or burst of light.
Ocular Migraines and Visual Auras
Yellow spots, along with shimmering or zigzag lines, can be a component of a temporary neurological event known as a visual or migraine aura. These disturbances are often incorrectly called an ocular migraine, but they relate to activity in the brain’s visual processing center rather than the eye itself. A visual aura typically presents as a shimmering, expanding area of light or color that may last between five and sixty minutes. The mechanism behind this visual disruption is Cortical Spreading Depression, a wave of electrical activity that moves slowly across the visual cortex, causing temporary functional disruption. The specific shape and color of the spots, lines, or blind spots depend on the precise path and intensity of this spreading activity.
A visual aura affects the visual field of both eyes, even if it seems to appear only in one. It may or may not be followed by a headache.
Persistent Spots and Macular Changes
When yellow spots become persistent features of central vision, the cause may relate to structural changes within the retina, specifically the macula. The macula is the small, central area of the retina responsible for sharp, detailed vision. One common finding in aging eyes is the presence of deposits called Drusen, which are explicitly yellow in appearance. Drusen are accumulations of fatty proteins and lipids that collect beneath the retinal pigment epithelium, the layer of cells supporting the photoreceptors.
While a few small Drusen are common with age and typically cause no symptoms, a larger number or size of these yellow deposits can signal the early stages of age-related macular degeneration (AMD). The presence of these deposits can interfere with the normal function of photoreceptor cells, leading to a perception of persistent yellow spots, blurring, or distortion in the center of the visual field. Small, defined “hard” Drusen carry a lower risk of advanced vision loss, while larger, softer, and less defined Drusen are associated with a higher risk for developing AMD. Since AMD affects central vision, it is often noticed when trying to read or focus on fine details, highlighting the importance of regular dilated eye exams to monitor these changes.
Urgent Symptoms Requiring Immediate Care
While many visual spots are benign, certain accompanying symptoms indicate a serious, sight-threatening emergency that requires immediate medical attention. A sudden increase in the number of spots or floaters, particularly if accompanied by flashes of light, suggests a potential problem with the vitreous gel pulling on the retina. The vitreous is the clear, gel-like substance filling the eye, and as it liquefies with age, it can tug on the retina, causing light flashes. This mechanical stimulation can lead to a retinal tear or retinal detachment.
A retinal detachment occurs when the light-sensitive tissue pulls away from the back of the eye. Other urgent warning signs include the appearance of a gray or dark “curtain” or shadow that moves across or blocks part of the vision. Immediate evaluation by an eye care professional is necessary for these symptoms, as a delay in treatment for a retinal detachment can result in permanent loss of vision.