Tetraflex™ Intraocular Lens (IOL)

The Natural Crystalline Lens

The crystalline lens is a refractive structure within the eye consisting of a transparent membrane filled with a transparent protein. The crystalline lens is responsible for approximately 40% of the eye's focusing power and can change its curvature in order to focus images of nearby objects in 
our environment. 

Accommodation is the term used to describe the mechanism for converging and diverging light that enters the eye during image production, changing the eye's refractive power by adjusting the shape of the crystalline lens.  Essentially, accommodation serves to maintain a clear focus on an object as it approaches the eye. During accommodation, the eye's ciliary muscle contracts, which allows the zonules (i.e., fibres that maintain the lens's position and suspend it from the ciliary body) to relax — increasing the curvature of the lens by thickening it at the centre and decreasing its diameter. This central protrusion and flattening of the lens's periphery occurs automatically to focus objects at different distances.

As part of the normal aging process, the eye's accommodative abilities decline. By the fourth and fifth decades of life, most individuals will notice a decrease in their ability to focus on near objects due to a loosening of ciliary muscle tissue, a progressive decrease in the clarity and elasticity of the crystalline lens as well as an increase in the lens's thickness, which affects its length, curvature and optical power. These lens changes begin very early in life, but tend not to interfere with clear near vision until after the age of 40. At this approximate age, when the lens tissue has hardened and lost its ability to change its curvature sufficiently enough to focus for reading vision, the condition is called presbyopia. When presbyopia occurs, individuals require reading spectacles to fine-tune vision for near tasks such as reading or sewing.

Eventually, the transparent protein within the crystalline lens loses its transparency and becomes discoloured. When the lens opacity begins to impair an individual's functional vision or block vision, we describe the condition as cataract, which can be surgically extracted. However, once the lens tissue is removed, spectacles, contact lenses or an intraocular lens (IOL) implant must replace the lost optical power of the natural lens to achieve visual correction. Today, ophthalmologists use the intraocular lens device as the most typical method of restoring optical power after natural lens extraction. NOTE: Cataracts may also develop as the result of exposure to ultraviolet (UV) rays, eye trauma, medications, disease, genetics or infection prior to birth and/or other factors.

Restoring Optical Power & the Tetraflex Intraocular Lens

The most commonly manufactured IOL implants are lenses that offer a single focus only, rather than multiple ranges of focus. This means, after lens extraction and single focus IOL implantation, a patient is reliant upon spectacles to fine-tune some ranges of focus (i.e., near, intermediate and/or distance vision — depending on patient preference).

Applying the properties of movement found in a boat's sail, Lenstec has developed the Tetraflex intraocular lens to provide individuals with near, intermediate and distance vision after natural lens extraction (i.e., cataract or Refractive Lens Exchange surgery). This type of intraocular lens provides a full range of vision by using the eye's natural forces activated during accommodation to move the optic forward and/or backward, which simulates accommodation and enables many patients to enjoy multiple ranges of vision without spectacle or contact lens dependence.

Basic Information About the Tetraflex Intraocular Lens

• The Tetraflex IOL's unique front angle orientation, the result of its patented 5° contoured haptic design, enables the lens to simulate accommodation — optimizing the optic for near, intermediate and distance vision. NOTE: Haptics are the extensions from the IOL optic that maintain the IOL's position after implantation.

• The Tetraflex optic has a 5.75mm diameter, which tends to reduce visual disturbances 
  (e.g., halos and glare) that are characteristic of IOLs with smaller diameters.

• The Tetraflex intraocular lens is the same co-polymer hydrophilic acrylic lens material as 1,000,000 other Lenstec manufactured IOLs. As some researchers believe that near UV blue light may be harmful to the retina and may contribute to macular degeneration and loss of vision, Lenstec manufactures the Tetraflex with a polymerisable UV blocker for filtering UV radiation and high-energy blue light transmitted within the sun's rays and artificial light.

• The Tetraflex is designed to provide a greater range of focused vision than a standard, single focus IOL and is intended to reduce or eliminate dependency on corrective lenses on a permanent basis after surgery.

• To strengthen and tone the mature and naturally loosened ciliary muscles after surgery, patients choosing the Tetraflex IOL are advised to improve their post-operative vision by performing daily focusing exercises, beginning within 24 hours after surgery. Some examples of focusing exercises are as follows:
  - Reading newspapers, magazines and/or books for 10-30 minutes
  - Doing crossword puzzles and/or word searches for 10-30 minutes
  - Continuing other daily reading and focusing activities (e.g., computer use, watching television, craftwork, writing, drawing, gardening, etc.)
  BEST PRACTICE TIPS
  1) Alternate every 15 seconds between reading or puzzle solving and focusing on an object in the distance (i.e., across the room)
  2) Continue focusing exercises until eyes tire
  3) If eyes tire within the first few minutes, stop, rest for 2 minutes and continue focusing until eyes tire again. Continue focusing exercises until 10-30 minutes of total focusing exercise time has elapsed.

• To achieve optimal post-operative results, patients selecting the Tetraflex IOL for insertion should avoid use of reading glasses after surgery. If necessary, patients may use reading glasses to perform critical near vision tasks after surgery, but are advised to attempt focusing without the assistance of reading glasses whenever possible.

• Typically, patients notice optimal post-operative intermediate and distance vision ~2-4 weeks after the Tetraflex IOL has been inserted into both eyes (i.e., ~2-4 weeks after the second eye's surgery appointment has occurred). If a patient complies with post-operative focusing exercise recommendations, near vision becomes optimal at ~4 months 
  after surgery.