Presbyopia is when the lens loses control power to focus on objects and the dependence on glasses has largely increased.
A cataract is a clouding of the lens which affects vision. Most cataracts are related to aging.
- 1. I am 55 years or older.
- 2. I suddenly feel my eyes to be dim.
- 3. My vision is cloudy and blurry.
- 4. When looking at oncoming headlights of a car or any bright light, I feel it is too bright or glaring.
- 5. Although I’m wearing glasses, objects don’t seem to be vivid as they once were.
- 6. Objects seem to be over-lapping.
- 7. I experience difficulty in bright places, especially when seeing nearby objects.
- 8. My vision seems to be clearer indoors or in dark places.
- 9. I am able to read or see close details better without my reading glasses.
※ If you can relate to four or more of the conditions listed above or have felt a recent change in your vision, you should consult your eye specialists to see if you should receive corrective surgery.
Cataract is the top ranking disease for the elderly (above 65 years old) with 190,000 surgical patients in 2014 and the number of patients is rising by 4% each year.
70% of cataract patients are in their 50s and 60s, proving that it is the most common senile ophthalmopathy that occurs as the eyes start to age. Cataract is most commonly due to aging but may also occur because of trauma, diabetes or be present from birth. The lens becomes cloudy and opaque which leads to a decrease in vision.
Senile cataract is part of the natural aging process. The lens in the eye consists of 60~70% water and 30~40% protein. As we age, the protein may clump together and start to cloud a small area of the lens.
※ Other risk factors for cataract other than aging include:
- Certain diseases: diabetes
- Personal behavior: smoking, drinking alcohol
- Ultraviolet radiation from sunlight or other sources
- Family history
- Precious eye injuries or inflammation
- Other eye diseases: uveitis, glaucoma, retina detachment
- Prolonged use of corticosteroid medication
A cataract starts out small and at first has little or no effect on your vision. You may then notice that your vision is getting a little blurry. Depending on the location of the lens opacity, vision impairment symptoms will be different. Partial opacity may cause monocular diplopia, also known as double vision.
The lens nucleus (the central portion of the lens) hardens and increases refraction, improving close-up/near vision. Sometimes this symptom is mistaken for presbyopia and is neglected. However, if neglected, it can be the leading cause for glaucoma and other complications. The location of opacity in the lens and the degree of it can affect how blurry and distorted your vision is. One of the characteristics of cataract is that although cloudiness has occurred, you are able to distinguish brightness of light and shadows.
Vision impairment due to cataracts can be treated with surgery, so if you start to feel your vision becoming blurry, you should contact your eye specialist.
- 1. Topical anesthetic eye drops are put in and a tiny incision (under 3mm) is made in the cornea.
- 2. A high-frequency ultrasound device breaks up and removes the cloudy lens. This procedure is called phacoemulsification.
- 3. A monofocal or multifocal lens is inserted in the same location as the removed natural lens.
※ What is phacoemulsification (ocular ultrasound)?
Pracoemulsification is a procedure in which an ultrasonic device is used to break up or emulsify the lens and then aspirate it from the eye. Unlike the standard method where a 8~10 mm incision had to made, only a tiny cut smaller than 3mm is made allowing a faster recovery without stitches.
Q.When should I have the surgery?A. Unlike with many diseases, you don't have to have cataract surgery right after being diagnosed with cataracts. It is generally recommended to have the surgery only when cataracts begin to prevent you from going about your daily activities. However, cataracts are left untreated for too long, surgical treatment may not be possible and the risk of getting glaucoma increases. Once you have been diagnosed, it is recommended that you get regular check-ups once every 6 months.
Q.Do I have cataract surgery on both eyes simultaneously?A. If you have cataracts in both eyes, surgery typically isn’t performed on both eyes at once. Surgery is performed on one eye first, and then a few days or weeks later it is performed on the second eye. This allows the first eye to recover and your vision in that eye to stabilize before surgery is performed on the other eye.
Q.Can I have cataract surgery even if I am very old?A. Just because you are old, it doesn't mean that surgery is impossible. Cataract surgery is performed under local anesthesia, so as long as you are healthy enough to cooperate during surgery, age is not a big factor.
The lenses of a young person have elasticity , and when looking at an object close by, the ciliary muscles contract and the lens becomes a think magnifying glass shape. This action is like the auto-focus function of a camera. The thickness of the lens changes automatically to control the focus distance. However as we age, the ciliary muscles and the elasticity in our lens weaken. When a monofocal lens is inserted, the lens loses this auto-focusing function.
There are two types of intraocular lens used in cataract surgeries:
01One focus point: monofocal intraocular lens
As monofocal intraocular lens has one focusing distance, it excels in correcting either distant vision or close range vision. Most people have them set for clear distant vision, and wear glasses for reading or close up work. Some may have them set for close range vision, and wear myopia glasses to look at things far away.
ㆍFocus of light with monofocal intraocular lens: Focus on only one distance
02More than two focus points: multifocal intraocular lens
Multifocal intraocular lens can improve both distant and close range focus at the same time. So cataract as well as presbyopia can be simultaneously treated. Also, unlike the monofocal lens, they reduce your dependence on glasses by giving you clear vision for more than one set distance.
There are many multifocal intraocular lenses to choose from; AT LISA, LISA-tri, LENTIS Comfort, Restor, Tecnis, etc.
ㆍThe Effects of Light Focusing through Multifocal Intraocular Lens: Provide Both Distant and Near Focus
AT Lisa / Carl Zeiss,
※ The meaning of LISA
L - Light districted asymmetrically : between distant (65%)
and near focus (35%) for improved intermediate vision.
I – Independency from pupil size : due to high performance diffractive micro-structure covering the complete optical diameter for excellent distant and near vision
S – SMP technology : for a lens surface without any square edges or sharp angles for ideal optical imaging quality with reduce light scattering
A – Aberration correcting optimized aspheric optic : better contrast sensitivity, depth of field, and sharper vision
※ Defocus: The distance you can see shortens as the focus measure declines (-1, -1.5…)
Improved Night Halo & Blurred Vision
AT LISA lens has a smaller diffraction difference than American brand multifocal ICLs, and the smooth lens surface reduces night blurring and is effected less by the brightness of light. According to a comparison between AT LISA ICLs and other multifocal ICLs, less than 10% of the patients who used AT LISA ICLs said they had mild/slight night blurred vision.
Contrast sensitivity: same as a normal person
Lisa-Tri / Carl Zeiss, Germany
Distant, intermediate, and close range vision can be improved with LISA-tri. The ZEISS LISA-tri offers an outstanding intermediate visual performance, as well as an improved distant and close range vision. It is an ideal presbyopic correction lens which restores both distant and intermediate vision.
※ Features of LISA-tri
- Improves the 70~90cm intermediate vision
- High performance diffraction reduces light scattering
- SMP technology smoothens the surface eliminating night blurred vision
- Refractive – diffractive micro structure improves all distant, intermediate, and close range focus
- The surface optic square edge minimizes late-onset cataracts
- Excellent visual acuity no matter the pupil size
- Secures maximum amount of light to the retina
- Daily routine possible the following day
LENTIS Comfort /Oculentis, Germany
LENTIS Comfort lens, produced by Oculentis Inc, Germany, optimally improves the 50~60cm interme- diate range. One part of the lens improves the distant vision, and the other part covers the interme-diate and near vision with +1.50D. Standard multifocal ICLs were mostly made to improve the close range vision, so the image quality of objects in an intermediate distance was not clear.
For those who don’t use a smart phone or read and basically have a lifestyle of not needing as much near vision may not need to improve their close range vision. So patients may need reading glasses when doing close range work.
With LENTIS Comfort, you won’t have trouble reading something that is 50-60cm away making it an excellent choice for those who do a lot of computer work. One of the known flaws of presbyopia correction lenses is halo vision which many patients experience because of the difference in power between distant and close-range vision was insufficient. With LENTIS Comfort, however, patients are ensured to have optimized vision with no halo effect.
※ Features of LENTIS Comfort
- Improves the 50~60cm intermediate range vision (Able to do computer work)
- Driving at night without any difficulties
- Reading small print is possible but may need reading glasses
TECNIS / AMO (Abbott Medical Optics), USA
Tecnis ®, Abbott Medical Optics, USA, incorporates as aspheric modified anterior prolate surface and a diffractive posterior surface, to simultaneously improve both distant and close range vision. The main feature, differentiating it from other multifocal lens, is that this 6mm silicon lens has a posterior full diffractive multifocal surface.
Based on the analysis of spherical aberration of cataract patients, Tecnis ® designed aspheric ICLs (Patented Wavefront-Designed Optic) to provide an ideal balance between the cornea and the intraocular lens for a sharp clear vision. This technology allows for a much more vivid image of distant objects both day and night.
※ Features of Tecnis ®
- Improves spherical aberrations for a sharp vision
- Excellent distant and close range vision
- 30~40cm close range vision drastically improved
- A clean day time vision as well as a satisfactory night vision
- Especially recommended to those who drive and read a lot
- The surroundings look blurry.
- Astigmatism develops on the slanting surface.
- Distortion forms due to astigma-tism.
- Less cloudy vision.
- Less color dispersion and less blurry surroundings.
- Less development of astigma-tism on the slanting surface.
- Thinner and lighter than spheri- cal lenses.
ReSTOR / Alcon, USA
ReSTOR, produced by Alcon, USA, means to “restore” your vision back to when you were young. This American FDA approved ICLs can improve both distant and close range vision after cataract surgery.
The apodized diffractive technology of ReSTOR has been FDA-approved. It automatically diffracts the amount of light reaching the retina, improving distant and close-range vision. Especially in the central zone, there are 12 concentric steps of gradually decreasing from 1/50 of a hair strand to 1/300. It is this technology that has improved the problems that presbyopia-correcting lenses had, such as unsatisfactory distant vision, impaired night vision, halo, and blurred vision.
Features of ReSTOR
- Can effectively treat both cataract and presbyopia at the same time as it automatically controls the amount of light reaching the retina
- This flexible lens only requires a small incision when implanted, leading to a fast recovery.
- Reduced unsatisfactory distant vision, impaired night vision, and halo and blurry vision
- Not only minimizes the risk of secondary cataract, but also as it is almost identical in color to the natural lens, filters harmful UVA and blue light to efficiently prevent senile macular degeneration
Apodized Diffractive Technology
The apodized diffractive optics is found within the central 3.6mm optic zone of the anterior surface of the ICL. This area comprises of 12 concentric steps of gradually decreasing (from 1.3microns to 0.2microns) step heights creating multifocality from near to distant. The overall result is that the lens acts like a distance monofocal correction with little loss in contrast with the images of distant objects to increase sharpness and to minimize visual defect.
SCI(Science Citation Index)
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