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Why Do Base Curve and Diameter Matter for Contact Lens Selection?

Mar 01,2024 | Ariana

Have you ever wondered about the mysterious letters and numbers printed on your contact lens case? What do BC and DIA stand for, and do higher numbers indicate better contact lenses? Let's walk into the world of contact lens specifications to unravel the secrets behind BC and DIA and how they influence your choice of contact lenses.

What is the Base Curve of Colored Contacts?

Base Curve (BC): the curvature of the back surface of the lens. 

It is also the radius of the fitting curve, an essential measurement that determines how well the lens conforms to the shape of your eye. A proper base curve ensures a comfortable fit, prevents irritation, and promotes healthy oxygen flow to the cornea. 

What is the Diameter of Colored Lenses?

Diameter (DIA): the size of the lens, specifically how much of your eye's surface it covers.

A larger diameter provides more coverage of the iris, enhancing the color-changing effect of the lens. However, it is important to balance coverage with comfort, as a lens that is too large may cause discomfort or interfere with blinking. 

Unibling Colored Contacts

Are the Base Curve and Diameter Important in Contact Lens Selection?

Yes, the base curve and diameter are paramount in contact lens selection.

  • Proper Fit and Comfort

A contact lens with an incorrect base curve can cause discomfort and irritation. With the right base curve, you can achieve a comfortable fit and avoid unnecessary eye irritation. Similarly, the diameter of the contact lens plays a significant role in comfort. If the lens diameter is too small, it may not cover the entire cornea properly, leading to discomfort and possible vision distortion. Choosing the correct diameter ensures that the lens covers the intended area of the eye while allowing for proper blinking and tear flow.

  • Vision Clarity

An improperly fitted contact lens can affect your vision clarity. If the base curve and diameter are not suitable for your eye shape, the lens may move around, causing blurred or distorted vision. Additionally, an ill-fitting lens may not align correctly with your visual axis, resulting in decreased visual acuity. By selecting the appropriate base curve and diameter, you can ensure optimal visual performance and clarity.

  • Eye Health and Oxygen Permeability

The base curve and diameter also play a role in maintaining good eye health. A well-fitted contact lens allows for adequate oxygen flow to the cornea, preventing hypoxia (lack of oxygen). The cornea relies on oxygen from the atmosphere, and a poorly fitting lens can hinder oxygen exchange, potentially leading to corneal issues such as edema and neovascularization. Opting for a proper base curve and diameter ensures that your eyes receive the necessary oxygen supply, promoting long-term eye health.

Unibling Blue Grey Contacts

Unibling Polar Light Blue Grey Contacts - A Base Curve of 8.6mm Suitable for Most People

To ensure optimal comfort, vision clarity, and eye health, Unibling prioritizes both the correct base curve and diameter. Unibling contacts come with a base curve of 8.5-9mm, which is in line with the majority of persons' ocular base curve between 8.4 and 8.6. With a properly fitting base curve, our colored lenses ensure overall comfort and vision clarity.

Besides, Unibling contacts have a diameter of 14mm-14.5mm, providing coverage of the iris for an enhanced color-altering effect while still allowing for proper blinking and tear flow. We use the golden ratio as a guide when selecting the proper graphic diameter, with a Sclera: Eyes: Sclera = 1:2:1 proportion to naturally enlarge your eyes.

How to Find the Right Base Curve and Diameter?

  • Eye Shape: The shape of your eyes is crucial when choosing the base curve and diameter of your colored contacts. Eyes can have different curvatures, ranging from flatter to steeper. An eye care professional can assess the shape of your eyes using specialized instruments and determine the appropriate base curve. For flatter corneas, a less steep base curve may be recommended, while steeper corneas may require a more curved base curve. By matching the base curve to the shape of your eyes, you can achieve a comfortable and secure fit.
  • Prescription: If you have a prescription for corrective lenses, it is essential to take that into account when selecting the base curve and diameter of your colored contacts. Astigmatism, for example, requires toric lenses with specific axis and cylinder measurements. Your eye care professional will consider your prescription and any astigmatism correction required when determining the base curve and diameter. Aligning the measurements with your prescription ensures that your vision remains clear and accurate while wearing colored contacts.
  • Lifestyle Factors: Your lifestyle also plays a role in choosing the right base curve and diameter. If you lead an active lifestyle, you may benefit from lenses with a more secure fit, ensuring they stay in place during physical activities. If you work extensively on digital devices, lenses with a larger diameter may be better in allowing for improved tear circulation and reduced dryness. Discuss your lifestyle needs with your eye care professional, who can recommend suitable base curves and diameter measurements tailored to your activities.

When choosing the right base curve and diameter for your colored contacts, it's essential to consult with an eye care professional. They will consider your eye shape, prescription, and lifestyle to recommend suitable options. Corneal topography may be conducted to ensure an accurate fit. Remember, finding the perfect fit may require some trial and error. Providing feedback during the fitting process and attending follow-up visits is crucial to ensure comfort, vision correction, and eye health. Ultimately, personalized recommendations based on these factors will help you select colored contacts that fit well and suit your lifestyle.

Unibling Adoring Blue Colored Contacts

Unibling Adoring Blue Colored Contacts - A Diameter of 14.2mm for Embracing Beauty and Eye Health

What's the Impact of Wearing Colored Contacts with the Wrong Base Curve and Diameter?

Wearing colored contacts with the wrong base curve and diameter can lead to various issues. Here are some impacts based on the search results:

  • Wrong Base Curve SymptomsUnusual lens movement, persistent eye discomfort, difficulty achieving clear vision, swelling or redness in the eyes, sensitivity to light, eye dryness, and excessive tearing can occur.
  • Wrong Diameter Symptoms: The lens easily dislodges or falls out, the lens feels too tight on the eye, difficulty in inserting or removing the lens, unusual lens movement, and eye discomfort or irritation may arise.

In addition to the symptoms mentioned, wearing colored contacts with the wrong base curve and diameter can also increase the risk of corneal abrasions, infections, and other serious eye complications. It's important to seek professional help from an eye care provider if you experience any discomfort or vision issues while wearing contact lenses.

Should I Shift the Base Curve and Diameter When Changing Lenses?

When changing colored lenses, it is important to reassess the base curve and diameter to ensure a proper fit. Different brands and types of colored contacts may have varying base curves and diameter measurements, so it is advisable to consult with your eye care provider before switching to a new lens. Adhering to the recommended base curve and diameter for each lens type will help maintain comfort, vision quality, and overall eye health.

Unibling: Clear Vision, Clear Choices - BC and DIA Matters

In Unibling, the purchase process adheres to FCLCA and customer regulations, and a prescription verification system has been integrated. As part of the checkout process, we require your input for specific parameters related to your eyes and nearsightedness from the table below, including BC and DIA. Upholding professionalism and compliance, Unibling prioritizes recommending the most suitable contact lenses to enhance eye aesthetics and safeguard eye health.