Second Sight Changes in Vision

“Second sight” refers to a temporary change in vision during early cataract development. Before vision deteriorates, vision, especially close-up reading vision, improves significantly. Some patients report very clear near vision without the use of reading glasses. Near vision refers to vision for objects 2 feet or closer to the viewer.

These changes occur because the proteins and other compounds that make up the lens begin to change structure. This, in turn, changes the way light refracts through the lens, causing a temporary improvement in near vision.

Close up of a woman's eyes
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Will Everyone Experience "Second Sight?"

Although we all experience the changes that occur inside our lens, the effects depend on what type of vision problem you had before, what the refractive status was with the eyes beforehand.

For example, if you were already nearsighted, "Second Sight" will make you even more nearsighted. People that experience the benefits of "Second Sight" are typically farsighted or have typically no vision problem to start with.

Why Does the Crystalline Lens Change?

Our eyes are constantly undergoing stress from outside factors. One process that our bodies are constantly fighting is oxidative damage, also referred to as oxidative stress. Oxidative stress is the constant battle that our bodies fight against free radicals, which are oxygen-containing molecules that are highly reactive and destructive to the cells in our body.

Oxidative stress can change the cells within the lens of the eye that cause the lens to slowly lose its transparency. Although this process occurs slowly all throughout our lives, it catches up to us when we get older and before it affects our vision significantly, we often experience "second sight."

What Is a Cataract?

A cataract is a clouding of the eye's lens. Cataracts are the leading cause of blindness among people older than 55. Most older people have some degree of lens clouding, which is a normal part of aging. A cataract is generally painless. It usually starts out as a small, opaque spot and slowly grows larger.

Vision is not usually affected until a large area of the lens becomes cloudy. Possible symptoms of a cataract are blurred vision, light sensitivity, halos around lights, difficulty driving at night, faded vision, needing more light to read, double vision or large changes in eyewear prescriptions.

What to Do If You Think You're Experiencing Second Sight

If you think that you are reading better lately without your glasses on, see your optometrist or ophthalmologist. If your near vision is suddenly better than ever, chances are that your distance vision may be worse. Sometimes, when second sight occurs, what is really going on is that you are becoming a bit nearsighted. Smaller amounts of nearsightedness can make your near vision better while making your distance vision blurrier.

Your eye doctor will measure your visual acuity and complete a refraction, the test you remember being asked, "Which one is better—one or two?" A refraction will show if your prescription has had a big shift. Your eye doctor will also dilate your eyes and look at them under a special bio-microscope to see if cataract development is occurring or you are just having a normal prescription change.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. University of Utah Health. Cataracts.

  2. Pescosolido N, Barbato A, Giannotti R, Komaiha C, Lenarduzzi F. Age-related changes in the kinetics of human lenses: prevention of the cataract. Int J Ophthalmol. 2016;9(10):1506-1517. doi:10.18240/ijo.2016.10.23

  3. American Academy of Ophthalmology. What Are Cataracts?.

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.