While the most common cause of cataracts is “having birthdays”, our nice way of saying, “getting older”, there are many causes of cataracts. The human lens forms prior to birth with thousands of small clear proteins packing themselves tightly into a thin shell. The size of the natural lens is approximately 3-4mm thick and about the size of a common household lentil. When the natural lens becomes cloudy it is then called a cataract. There are many types of cataracts, each one developing for a different reason. In this article, we’ll review some of the most common causes of cataracts.

Symptoms of Cataracts

Cataracts grow slowly over time and patients sometimes do not notice their effects until they begin impacting their activities. Common symptoms of cataracts include cloudy vision, halos around lights, dark or dim vision, and poor night vision. Frequent changes in glasses occur as well as increased near vision.

Aging Is The Most Common Cause Of Cataracts

Elderly man showing causes of cataracts
By far the most common reason for cataract development is due to advancing age. This occurs because the proteins within the lens continue to divide and grow throughout life within a confined space. After decades of growth, the lens begins to thicken, a process called nuclear sclerosis. These lens proteins also discolor leading to changes in the way light and color are filtered and viewed. Although not completely understood, there are some factors of daily life that can speed up the development of cataracts. These factors include spending time in bright sunlight without sunglasses, smoking, and an unhealthy diet.

Medications Can Cause Cataracts

The most common medication that causes cataracts are oral, intravenous, and inhaled steroids. This type of cataract forms within 5-10 years of medication use and is most commonly termed a posterior subcapsular cataract. Although these cataracts can be quite visually disturbing, they are straightforward to remove, and visual recovery is quick.

Trauma and Prior Surgery Can Cause Early Cataracts

Blunt forces to the eye or surrounding face can cause a special type of cataract called a “stellate cataract”. As the proteins within the natural lens undergo extreme pressure and movement they begin to cloud and swell. Over time the lens becomes pressurized and requires special considerations during surgery as well as a higher risk of complications. Experienced cataract surgeons have all the skills necessary to handle these situations and still help patients achieve excellent vision. Other procedures inside the eye such as retinal surgery and refractive surgery (PRK, LASIK, ICL) can disturb the delicate lens and cause it to cloud. These cataracts typically develop slowly over time.

Congenital and Medical Conditions That Are Causes Of Cataracts

The list of medical conditions that can cause a cataract is extensive, but the most common medical condition that causes cataracts is diabetes. As the bloodstream takes on more glucose, the lens begins to change its energy demands. This leads to swelling within the lens and changes to its shape and size, leading to cataract development. This type of cataract is termed a “snowflake” cataract.

In rare circumstances an infant can be born with cataracts, these are called congenital cataracts. Any child with cataracts needs a full comprehensive exam with a pediatric ophthalmologist to rule out dangerous metabolic diseases, retinal problems, and rare malignancies.


Although there are many ways that cataracts can develop, the surgical treatment of cataracts is straightforward with a high success rate. Patients can look forward to better vision and decreased reliance on their glasses and contacts with an experienced surgeon offering the latest options for cataract surgery with intraocular lens replacement.