Deceptive Vision

The human eyeball works with the brain to help people see images. It does this using many parts and the properties of reflection. Sometimes, the eye has trouble decoding colors or text.  Certain medical conditions can make people see lights that are not present.

Objects that do not emit their own light must reflect light for people to see them, a property called reflection. In reflection, two rays of light are at work, an incident, or incoming, ray and a reflected, or outgoing, ray. All light incidences and reflections hit an object at the same angle on opposite sides of the normal — an imaginary line that divides the reflection angle evenly. Every time a reflection passes through the air, water, or glass — it refracts or bends. How much light reflects into the eye depends on the refractive properties of the eye and the corrective lenses a viewer wears. Opticians use this property to help correct vision errors.

The eye sees different light types called wavelengths as different colors. Different cones (special light receptive cells in the eye) receive different wavelengths. Humans normally have three cone types: L, M, and S.

L cones ( long-wavelength cones) receive red light.

M cones (middle wavelength cones) receive the green light.

S cones (short-wavelength cones ) receive blue light.

In order for cones to send a color signal to the brain, light must stimulate the cone. In turn, the brain will interpret the signals.

Color deficiency is the incapacity to differentiate some or all color shades. The condition is commonly called color blindness. The most common color blindness prohibits viewers from seeing colors in the red and green color spectrum. A less common type of color blindness prevents viewers from seeing yellow light. Achromatopsia is the complete inability to see color. It causes people to see only black and white light color shades. These symptoms can range from slight to extreme in nature, and people normally acquire the condition through heredity.

Dyslexia is a reading disorder diagnosed in five to ten percent of people. Of dyslexic people, about 70 to 80 percent have difficulty reading. The brain causes this condition by the way it interprets reflected lights. Dyslexia can occur in people with normal vision. What a dyslexic person sees is not limited to one type of vision error; each person suffering from this condition can misinterpret text differently. Dyslexic people may see some letters or numbers backward or out of order. Some see letters squeezed together. There are almost a dozen ways a dyslexic person’s mind can misinterpret written information. Fortunately, because of the common awareness of this ailment, opticians can diagnose this condition in young children and help parents learn how to teach their kids skills to manage this condition.

Flashers and floaters are visible lights that a person sees, but that do not appear real. Many people refer to floaters as “seeing stars.” Alternatively, they see light appear as a thread that floats across their field of vision. These images are not an object.  Rather, they are a shadow cast on the viewer’s retina. People can see flashers as strands of light that strobe across their optical field. These occur when aqueous gel collides with, brushes against, or pulls at the retina. Most floaters and flashers are harmless. However, if they suddenly begin to occur, get your eyes examined immediately. The eye works with the brain to help a person see.  It is a complex organ composed of multiple parts. At times, a person may have difficulty interpreting images correctly. Fortunately, modern science allows opticians to find, and correct vision, problems early.