The visible portion of our eye constitutes only a small part of the entire eyeball. Most of the area of the eyeball remains hidden from view within the socket or orbit of the skull. The portion of the eyeball that is visible includes the pupil, iris, cornea, and a part of the sclera. The iris is a circular muscle that determines the color of our eyes (shades of brown, blue, and green). This circular muscle encircles a hole (called the pupil) through which light enters the eyeball.
The contraction and relaxation of iris controls the size of the pupil, which determines the amount of light that enters the eyeball. The sclera is the white part of the eye that surround the colored iris. The cornea is the outermost transparent layer of the eye that helps in refracting the light. Variances in the size of the eyes can be due to multiple factors. In most cases, when people refer to differences in the size of the eyes, they are referring to variations in the visible portion of the eyeball.
These variations are usually due to the particular shape of the eyes that is determined by the eyelids and the skin around the eyes. These variations in the shape of the eyes are readily seen in different ethnicities, and are determined by genetic factors. However, it is important to understand that these variations in the shape of the eyes are not due to changes in the shape or size of the eyeballs.
Apart from normal physical variation in the shape of the eyes in the human population, one may also see the size of the eyes change in the same individual. Such sudden changes need to be investigated. If the eyes suddenly appear shrunken in a person, it is unlikely to be caused by an actual shrinking of the eyeball. Such shrunken eyes could be due to changes in the extent to which eyelids are able to open or increased puffiness or swelling in the region around the eyes.
Loss of fat from the facial region could also cause the appearance of sunken eyes. This is usually seen in the elderly. Shrunken eyes may also be caused by dehydration. In some cases, the appearance of smaller eyes may be due to cosmetics used around the eye region.
Causes of Shrunken Eyes
In most cases of shrunken eyes, there is no change in the size of the eyeball itself. Shrunken eyes may also be accompanied by other symptoms such as tears, redness in the eyes, and changes in visual capabilities. These changes may affect either one eye or both the eyes, and can help in understanding the underlying cause of shrunken eyes.
Heaviness of eyelids is a common occurrence when we are feeling sleepy. It is difficult to keep eyes open when we are sleepy, sleep deprived, or just plain tired. The eyes look small or shrunken in this sleepy state. Prolonged sleep deprivation can also cause puffy eyes, which further create the impression of shrunken eyes. Heaviness affects both the eyelids in these cases. The shrunken appearance of eyes due to sleepiness or sleep deprivation is a temporary condition. Getting enough sleep reverses the condition and the eyes regain their normal appearance.
Eye Strain is another frequent cause of shrunken eyes. Eyestrain is a common condition in the present day world in which electronic screens dominate our lives. Staring at bright screens on computers, phones or television sets for a long time is a common cause of eyestrain.
Reading for long periods of time can also result in eyestrain. Eyestrain is common when we work or study in rooms which have poor ambient lighting. Both the eyes get affected by eyestrain. Drowsiness could also occur as a result of fatigue caused by chronic eye strain.
Swelling of the area around the eyes can occur due to various types of injuries. Inflammation caused by the injury is responsible for such swelling, which can cause the eyes to appear small or shrunken. Trauma and inflammation can affect either a single eye or both the eyes.
A bruise around the eye can result in what is commonly referred to as a “black eye”. The swelling usually subsides as the inflammation peters out. Not all injuries that result in swelling are caused by forceful trauma. Vigorous rubbing of the eyes can also cause injury and inflammation in the region around the eyes.
Visual problems such as hypersensitivity to light and poor eyesight can also cause the appearance of shrunken eyes. People suffering from such problems tend to squint or close their eyelids, which makes their eyes appear smaller. Closing the eyelids partially or fully in the presence of a bright light is a normal physiological reaction. However, some individuals may be hypersensitive to light, causing them to close their eyelids even in the presence of moderate ambient lighting.
Such hypersensitivity to light is often seen during sleep deprivation or eye strain. The underlying cause could also be a serious disease such as meningitis. People who have defective vision and do not wear eyeglasses or contact lenses also tend to squint. Undiagnosed and uncorrected myopia (also known as nearsightedness) is a frequent cause of squinting.
Blepharitis refers to an inflammation of the eyelids. There are multiple potential causes of blepharitis, including allergies (such as dermatitis), infections (such as conjunctivitis), and trauma. The inflamed eyelids swell, making the eyes appear smaller than normal.
Cellulitis refers to a serious bacterial infection. As the name suggests, periorbital cellulitis is an infection and inflammation of the soft tissues that are present around the orbital area. In many cases, periorbital cellulitis is preceded by infectious sinusitis and upper respiratory tract infections. These infections can spread to the periorbital area and other places in the head region. Like other types of cellulitis, periorbital cellulitis requires immediate medical treatment.
Shrunken eyes could also be caused by drooping eyelids (also known as ptosis). The opening and closing of the eyelids are controlled by nerve signals that elicit contraction of the muscles responsible for the movements of the eyelids. Disorders that affect these muscles and nerves can result in ptosis.
Examples of some conditions that may cause drooping eyelids include brain injury, myasthenia gravis, multiple sclerosis, and Bell’s palsy. These conditions may affect either one eye or both the eyes. Reduced muscle tone caused by aging can also cause drooping eyelids and shrunken eyes.
Some surgical procedures (such as cosmetic facelifts) applied to the facial area can inadvertently make the eyes look smaller. This is usually unintentional.