When monochromatic light transitions from a denser medium to a rarer medium, the color perceived by an observer does not change because the frequency of light remains constant across both media. Although the wavelength differs, the color is fundamentally linked to frequency, which is unaffected by the medium change. Concerns about wavelength in different media are less relevant since the observer's retina operates in a consistent medium. The discussion highlights the importance of understanding light behavior in contexts such as ophthalmology, particularly regarding laser applications. Ultimately, the perceived color remains consistent despite variations in wavelength due to medium changes.