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Scleral

What Is the Shape of a Healthy Eye and How Does It Affect Vision?

eyes eye care 640x350The human eye is a biological piece of functional art, capable of producing colorful moving three-dimensional images with high precision. At the same time, one can marvel at the aesthetic beauty of the human eye and its shape.

The Shape of a Healthy Eye

In a healthy and perfectly shaped eye, light passes through the cornea and crystalline lens, and is accurately focused onto the retina, located at the back of the gel-filled eyeball. This process enables an image to be passed onto the optic nerve and then the visual cortex of the brain. Accurate focus and convergence depend on the proper shape of each part of the eye. However, eyeballs can be either shortened (hyperopia) or elongated (myopia).

Unhealthy Eye Shapes That Impact Vision

The Myopic Eye

In an elongated myopic eyeball, the distance between the lens and retina is too long, leading the image to come into focus before reaching the retina. As a result, the photosensitive cells of the retina pick up a blurry image.

The Hyperopic Eye

In hyperopia or farsightedness, the opposite is the case. The eyeball is too short, as is the distance that light travels from lens to retina. Therefore, the image comes into focus behind the retina, causing distant objects to appear clear, whereas close ones do not come into proper focus.

The Cornea

While the crystalline lens is flexible and auto-adjusts its shape for proper focus, the cornea is static. A healthy cornea maintains its smooth dome shape. However, if the cornea is weak, the structure of the cornea cannot hold this round shape, causing the cornea to bulge outward and downward like a cone. Perfect curvature of the cornea ensures the correct bending of incoming light onto the lens, whereas inadequate curvature results in a refractive error.

An uneven or irregularly shaped cornea also distorts the image that forms at the retina. Common corneal irregularities include astigmatism and keratoconus.

Keratocoonus Labelled

Scleral Lenses for a Smooth Eye Shape

Scleral lenses are large contact lenses that rest on the sclera — the white part of the eye. The lenses span over the cornea, making them ideal for a deformed cornea as they even out the irregularity to create a perfectly shaped eye.

Contact Dr. Yim at The Pacific Scleral Lens Center to learn more about how your eye shape affects your vision. We’ll be happy to discuss the different correction methods available that offer you sharp, comfortable and clear vision all day, every day.

We receive clients from Huntington Beach, Anaheim, Irvine, Long Beach, and throughout California.

 

Resources:

https://www.lasikmd.com/blog/eye-shapes-affect-vision

https://www.everydayhealth.com/vision-center/the-healthy-eye/how-the-eye-works.aspx

https://www.nvisioncenters.com/eye-shapes/

https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/refractive-errors

Ever Wonder How People See Following a Corneal Transplant?

Dry Eye Senior Woman 640×350For patients with a damaged cornea, corneal transplant surgery (also called keratoplasty) can help restore clear vision by replacing the original cornea with healthy corneal tissue from an organ donor.

Corneal damage can be caused by:

  • Corneal scarring from infection or injury
  • Keratoconus – an eye disease that causes the cornea to bulge
  • Corneal ulcers
  • Eye diseases, such as Fuch’s dystrophy
  • Clouding or swelling of the cornea
  • Complications following eye surgery

During surgery, either a portion of the cornea or the entire cornea is replaced with healthy tissue. Depending on the type of surgery, stitches may be needed. In all cases, however, a patch will be required to shield the recovering eye for 1-4 days after the procedure. Your doctor will instruct you on which medications to take and how to care for your eye in the days and weeks following the surgery.

If you require a corneal transplant or have already undergone the procedure, speak with Dr. Yim or one of the knowledgeable staff members at The Pacific Scleral Lens Center about how to safely regain clear vision after surgery.

How Is Vision Impacted After a Corneal Transplant?

Full recovery from the surgery may take up to a year, and sometimes longer. In the first few months after the procedure, your vision may even get worse before it gets better. As the eye adjusts to the new cornea, you may experience blurred or unstable vision, which will improve with time.

There is also a high chance of developing post-surgery refractive error— such as myopia or astigmatism — as the new cornea may have a different curvature than your original cornea. These refractive errors are generally corrected with either glasses, rigid gas-permeable (RGP) lenses, or scleral lenses. In many cases, scleral lenses are the better choice for post-keratoplasty, and for several reasons (explained below).

Why Are Scleral Lenses the Better Choice After Corneal Transplants?

Scleral lenses have a larger diameter than standard soft or gas-permeable lenses, making them more comfortable to wear while providing clear and stable vision. If there is a high variance in corneal curvature or even a slight elevation at the site of the transplant, RGP lenses may decenter, causing irritation and inflammation. Scleral contact lenses prevent this problem as they don’t sit directly on the cornea, but rather vault over it.

Furthermore, scleral lenses support the eye’s natural healing process due to the reservoir of fluid that sits between the cornea and the back of the lens. This keeps the eye in a constant state of hydration for optimal recovery.

Ever Wonder How People See Following a Corneal Transplant? from EyeCarePro on Vimeo.

Call The Pacific Scleral Lens Center to find out more about scleral lenses and to determine whether they are right for you.

Dr. Yim serves patients in Huntington Beach, Anaheim, Irvine, Long Beach, and throughout California.

REFERENCES

https://www.allaboutvision.com/conditions/cornea-transplant.htm

https://www.reviewofcontactlenses.com/article/postkeratoplasty-consider-sclerals

https://www.webmd.com/eye-health/cornea-transplant-surgery#1