A common question about post-mortem changes concerns the eyes: do they turn white? This notion is often perpetuated in popular culture. However, scientific understanding reveals that while significant alterations occur, the eyes do not actually turn white. This widely held belief is a misconception.
Initial Eye Changes Upon Death
Immediately following death, the eyes undergo several observable changes due to the cessation of bodily functions. One of the earliest signs is the pupils becoming fixed and dilated. This occurs because the muscles controlling pupil size lose their tone and relax as oxygen supply ceases. Without brain activity, the pupillary reflex, which normally constricts pupils in response to light, becomes absent.
Concurrently, the corneal reflex, an involuntary blink triggered by touching the cornea, is lost. This absence of reflex, combined with facial muscle relaxation, means blinking ceases entirely. These initial changes are direct consequences of the brain no longer sending signals to the eye muscles.
The Truth About Eye Color Post-Mortem
Despite popular belief, the colored part of the eye, the iris, does not turn white after death. Its color is determined by stable melanin pigments and cellular structure, which do not rapidly degrade or change.
The misconception that eyes turn white likely stems from other post-mortem changes affecting eye clarity and appearance. While the iris retains its original hue, a hazy film or clouding can form over the eye’s surface. This may appear as a bluish-gray or milky tint, obscuring the true iris color and leading to a mistaken impression of color transformation.
Understanding Corneal Clouding
Corneal clouding, also known as corneal opacity, often leads to the “white eye” misconception. The cornea is the normally clear, transparent outer layer covering the iris and pupil. After death, the cornea loses its transparency and can become hazy or opaque. This clouding typically begins within minutes to a few hours after death, appearing as a milky or bluish-gray film.
This change occurs due to several biological processes. Without the active metabolic processes of a living body, the corneal cells begin to dehydrate, especially if the eyelids remain open and the eye is exposed to air. Additionally, cellular breakdown and protein denaturation contribute to the loss of clarity in the corneal tissue. The system that maintains corneal transparency by actively pumping ions and water also ceases to function, leading to swelling and clouding of the tissue.
The timeframe for corneal clouding can vary; it might be observed within minutes if the eyes are open, or it could be delayed by many hours if the eyelids are closed. Environmental factors such as temperature can also influence the rate of clouding, with warmer conditions potentially accelerating the process.