Final answer:
The usual color of the ocular fundus is orange to red, influenced by blood vessels and retinal pigments. Abnormalities and health conditions may alter this appearance. Red-green color blindness is the most common color vision deficiency and could affect the perception of fundus color.
Step-by-step explanation:
The usual color of the ocular fundus, which is the interior surface of the eye opposite the lens including the retina, optic disc, macula, and posterior pole, is orange to red. This coloration comes from the presence of blood vessels and the retinal pigment epithelium. When an eye doctor examines the ocular fundus using an ophthalmoscope, they may observe various colors if there are any abnormalities. For example, if there's inflammation of the conjunctiva with nodules that are dome-shaped structures, they would appear red at the base and pale on top. Heart conditions can also impact the appearance of the fundus, such as in individuals having two-lobed nucleus cells that are obscured by dark purple granules. Additionally, color vision deficiencies affect how individuals perceive the world, with the most common deficiency being red-green color blindness.
Red-green color blindness affects approximately 8% of males of European Caucasian descent, among other demographics, and implies a different perception of the fundus color. Yet, the vitreous humor inside of the eyeball, unlike the conjunctiva, is typically sterile and does not influence fundus color unless pathology is present.