Bifocal intraocular contact lenses

Symptoms and progression of presbyopia

When presbyopia begins to develop, if you suddenly look into the distance while reading a book, your focus will immediately focus when you are young, but when you start presbyopia, blink your eyes and focus after a while. It takes time to focus near and far.
And it is easy to feel fatigue of the glasses. For example, working at the desk for a long time will make the eyes more fatigued. Just as people with good vision start presbyopia with age, people with myopia also start presbyopia with age. The symptom of presbyopia of myopia is the use of traditional glasses and contact lenses, which can clearly see the distance, but the near eyes are very blurred.

With the development of presbyopia, even if you try to adjust, it is difficult to focus, resulting in the inability to see close objects clearly. As shown in the figure below, the focal point is 17 cm at the age of 30, 25 cm after the age of 40, and as high as 50 cm at the age of 50.

Presbyopia supplements and presbyopia treatment

Supplements that are said to be good for the eyes include lutein, astaxanthin, vitamin A and blueberries. In addition, there is Hachimijiogan, which improves blood flow and water metabolism in the eyes, as a traditional Chinese medicine that is good for blurred vision.
Although these supplements and Chinese medicine are recommended as a measure against eye strain, there is no clear medical basis for the preventive or therapeutic effect of presbyopia.
However, since presbyopia is an aging change, it is also a fact that lutein and astaxanthin are attracting attention in anticipation of antioxidant effects as anti-aging.
If you want to treat presbyopia instead of correcting it with eyeglasses or contact lenses, surgery is still an option.
When treating presbyopia by surgery, those who have already started cataract after the age of 50 to 60 can treat presbyopia as well as myopia and astigmatism by using a bifocal intraocular lens in cataract surgery.
On the other hand, if you are between the late 40s and 50s and are still early in cataract surgery, you can cure presbyopia as well as myopia and astigmatism with bifocal contact lenses.

Features of typical multifocal lenses

【Refractive type】

A lens with a structure in which distant and near lenses are alternately combined concentrically. because it is made of the same refracting surface as monofocal, the vision is good, and especially for distant vision, the vision equivalent to that of monofocal can be obtained. The disadvantages are that it is easily affected by the pupil diameter and that halos and glare are likely to occur.

【Segmental refraction type】

A lens with a structure that combines distant and near lenses up and down. A structure that can eliminate the influence of pupil diameter while maintaining good contrast sensitivity, which is a merit of the refraction type. Halos and glare is relatively less, but the intermediate distance is hard to see clearly.

【Apodized ophthalmic type】

The diffractive reflex structure is a zigzag-like step that extends outward and gradually decreases, and the outermost portion is monofocal lens. The near distance is slightly farther, and the myopia effect in dark places is poor, but it improves the problems of low contrast sensitivity and halo and glare.

【EDOF extended depth of focus type】

By widening the depth of focus (distance of focus), the range that can be seen clearly is expanded, making it easier to see continuously from a distance to an intermediate distance. While the viewing distance of lenses with other structures is "points", "bands" provide a wide and natural look. It has a feature of less halo glare, but its near vision is a little poor.

Differences between mono-focus intraocular contact lenses and bifocal intraocular contact lenses

【How to focus a single focus intraocular contact lens (ICL)】

【Bidirectional intraocular contact lens: how to focus an extended depth of focus lens】

【Bidirectional intraocular contact lens: how to focus an apodized diffractive trifocal lens】

Bifocal contact lens

Manufacture and sale: STAAR Surgical

【Features】

• The lens material is Collamer, which is exactly the same as ICL, which has a proven track record of over 20 years.
• As the ICL, there is a small hole in the center of the lens to allow the aqueous humor to circulate naturally.
• The mechanism of presbyopia correction is EDOF (extended depth of focus), which has a proven track record in multifocal intraocular lenses for cataract surgery.
• The power standard is wide from -0.50 to -18.0D, and it can handle from mild to severe myopia.
• The sizes are 12.1mm, 12.6mm, 13.2mm and 13.7mm, which are the same as ICL.

• ① The lens material is Collamer, which is exactly the same as ICL, which has a proven track record of over 20 years.
• ② As the ICL, there is a small hole in the center of the lens to allow the aqueous humor to circulate naturally.
• ③ The mechanism of presbyopia correction is EDOF (extended depth of focus), which has a proven track record in multifocal intraocular lenses for cataract surgery.
• ④ The power standard is wide from -0.50 to -18.0D, and it can handle from mild to severe myopia.
• ⑤ The sizes are 12.1mm, 12.6mm, 13.2mm and 13.7mm, which are the same as ICL.

【Depth of focus curve before and after surgery】

Packer M, Alfonso JF, Aramberri J, et al. Performance and Safety of the Extended Depth of Focus Implantable Collamer ® Lens (EDOF ICL) in Phakic Subjects with Presbyopia. Clin Ophthalmol. 18: 2717-2730, 2020.(quotation)

It can be seen that it is easy to see with a gentle curve from far to middle and near (dotted line is the postoperative curve).

Merits

■ Can treat myopia and presbyopia at the same time

Presbyopia can be corrected with the latest version of ICL, an intraocular contact lens that has a proven track record in correcting myopia.

■ The characteristics of presbyopia correction are the same as those of multifocal intraocular lenses for cataract surgery.

The mechanism of presbyopia correction is the same depth-of-focus expansion type or diffraction type as the structure that has been used in multifocal intraocular lenses for cataracts that focus from far to near.

■ Can correct a wide range of people from early presbyopia to those with advanced presbyopia.

■ Presbyopia correction effect of + α that preserves accommodation power

■ Although it has obtained the European CE mark, it has not been approved by the US FDA or the Japanese Ministry of Health, Labor and Welfare.

■ Reduction of halo and glare

With an extended depth of focus lens can reduce the shortcomings of multi-focus lenses such as halo and glare.

■ Elimination of postoperative complications

Postoperative cataracts and glaucoma are extremely rare because they have a central hole similar to ICL (intraocular contact lenses).

■ The lens can be replaced when presbyopia progresses or removed in case of emergency.

Demerits

■ The insertion record is shorter than the myopia lens.

■ Although it has obtained the European CE mark, it has not been approved by the US FDA or the Japanese Ministry of Health, Labor and Welfare.

■ The characteristics of presbyopia correction are the same as those of multifocal intraocular lenses for cataract surgery.

■ Because it is made to order, the cost will be higher than other corrective surgery. In addition, returns and refunds are not possible after ordering lenses.

■ Surgery will be performed as soon as the ordered lens arrives, but it will take an average of 2 to 3 months for the lens to arrive.

■ It may be difficult to see in dimly lit places, and light reading glasses may be required for fine characters.

■ After surgery, you may see a ring of light in addition to mild halos and glare. However, this symptomatology becomes almost unnoticeable one month after surgery.

■ Although it is rare after surgery, if the power and size of the lens do not match, it may be necessary to replace the lens.

■ Because it is an internal eye surgery that puts a lens in the eye, pre- and post-operative care is very important. The probability of developing an infection is said to be about 1 / 6,000, which is extremely rare, but be sure to follow the precautions and eye drops before and after surgery.