Say Bye Bye to Trifocals, Bifocals and goodbye Readers too. While bidding adieu, say good riddance to contact lenses too.
Binocularity is better than monovision
PIE outshines Lasik Vision
What is PIE Eye Surgery?
PIE eye surgery stands for Presbyopic Implant in Eye (PIE). This vision technology allows you to see near & far without glasses in each eye. After the procedure, there is no need for any visual aids for the rest of your life.
The PIE procedure treats the ailment known as Presbyopia using presbyopia-correcting lenses.
Let us understand the meaning of each word in the acronym. The expanded form of PIE is “Presbyopic Implant in Eye.” The term has nothing to do with the mathematical term pi used in mathematical calculations.
Presbyopia is a natural change in the natural lens of the eye that occurs over time and affects one’s ability to see near objects. Generally, around age forty- five years old, individuals begin to experience this condition and it continues to progress as we age. To correct this condition most people begin to wear reading glasses.
Even those individuals that have undergone Lasik earlier in life feel the need to reach for reading glasses. People who already were wearing glasses would graduate to more cumbersome bifocals or progressives. Presbyopia makes it increasingly difficult to focus on objects near, middle and far. Presbyopic, in the term “Presbyopic Implant in Eye” means that it cures presbyopia.
The implant is a newer, synthetic, biocompatible lens placed in the space of the remaining natural lens after the old contents have been removed. Biocompatible means that the body will accept it and not develop any allergies, nor reject the new lens. Presbyopic Implant in Eye are specialized, groundbreaking lenses developed by optical engineers utilizing the latest techniques of Nano engineering.
The implants allow the eye to see near, middle and far. They are of different shapes and sizes. PIE can be defined as exchanging the contents of an improperly functioning, old natural lens with a newer artificial inert Presbyopic Implant in Eye, which can help us see at all distances and decrease, or even eliminate, dependency on glasses or contact lens.
PIE is the creme de le creme of methods to rejuvenate aging eyes. It is superior to other methods which combat the effects of taking too many revolutions around the sun.
Details About Presbyopic Implant in Eye (PIE) Surgeries
- Detection Analysis: IOL Master or Lenstar bio-metric devices measure the length and shape of the eye. They utilize advanced formulae to help determine the power of the Presbyopic Implant in eye need to get the optimum outcome.
- Equipment For Surgery: Recent generation machines like Centurion by Alcon, Stellaris Elite by Bausch & Lomb and Whitestar Signature Pro by Johnson & Johnson are necessary.
- Variations in procedure: Toric Presbyopic Implant in eye can treat the existing astigmatism at the same time. Istents, or similar devices, may used to treat mild to moderate glaucoma.
- Indications: To cure simple presbyopia or presbyopia associated with myopia, hyperopia or astigmatism
- Contraindications: Sever macular degeneration, advanced glaucoma with visual field defect and proliferative diabetic retinopathy.
Benefits of Presbyopic Implant in Eye (PIE) surgery
Imagine getting up in the morning and looking at the alarm clock with your naked eyes. You then grab your smart phone to check your email and the latest status updates from your friends on Facebook. While eating breakfast you skim through the newspaper.
Continuing the trend, you drive with no glasses to work and then go on to play golf. After playing the best golf of your life, you get a quick swim in, which is a pleasure without glasses or contacts.
On your way home you pick up groceries without squinting to read labels. While catching up on bedtime reading, you wonder why you did not get this unbelievable rejuvenating therapy before.
Learn all about the vision enhancing procedure, in an easy to understand book.
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Why is PIE more advantageous than glasses?
- Glasses can get foggy in the rain
- Swimming while wearing glasses is a challenge
- You can’t take in the beauty around you while scuba diving with glasses on
- A simple rainy day compromises your vision
- Glasses are easy to lose and break
- Both kids and pets can damage your glasses
- Glasses get smudged, scratched, and dented again and again
- You can fill in the blank with your own problems with glasses here
It’s safe to say PIE overcomes all these nuisances. Below are a few more reasons why this procedure is beneficial compared to other forms of correction.
Presbyopic Lens Implants gives binocularity which is better than monovision
Monovision is a process of setting the focus of one eye on close-up objects and the focus for your other eye on far-away objects. In doing this, your brain combines the two images to create a clear picture. This is a relic from the twentieth century. The primary disadvantage with monovision is one looses their binocular vision.
PIE allows you to preserve your binocular depth of field vision.
PIE is superior to multifocal contact lenses
Multifocal contacts move with every blink. The image presented to the brain fluctuates, confusing the brain. That is why many people are not able to adapt to multifocal contact lenses.
Presbyopic Implant in Eye are stable and do not move. The brain neuroadapts to the lenses, improving vision.
Contacts can lead to sight threatening cornea infections for as long as you wear them. Presbyopic implant in eye are not exposed to the elements or bugs.
Types of PI or Presbyopic Implants
There are four classes of FDA approved PI. These are Accommodative, Extended Depth of Field (EDOF), Trifocal and Multifocal.
A surgeon who is a PIE expert needs to be proficient in all different classes and types of presbyopic implant in eye. Success is truly achieved when the patient’s goals and desires are understood and the best PI for those needs is implanted.
Personality, work, hobbies and sports all influence the decision for the final implant chosen. This may even sometimes involve implanting a different class of PI in each eye.
Accommodative PI
This class of PI were the first to be approved by FDA in 2005. They heralded the advent of PIE. Crystalens was the first out of the stable. It had various modifications until it evolved into Crystalens HD and now we have Crystalens AO and Trulign.
They are made of silicone. Crystalens AO has aspheric optics whereas Trulign has aspheric optics and built in astigmatism correction. They work by assuming a curved shape in the eye, increasing the range of focus. This shape and the unique design of the lens may also allow it to move forward and backward, mimicking the natural lens. This lens has proved very useful in patients who have had previous eye surgery like Lasik vision correction, Radial Keratotomy and other corneal procedures. (Presbyopic Implant in Eye)
Crystalens is an accommodating posterior chamber intraocular lens made of silicone. It is a modified foldable plate haptic lens with hinges across the plates adjacent to the optic. Two flexible colored polyamide loops are attached to the distal extremity of the plates. It has a 5 mm optic zone, excellent contrast sensitivity, and minimized issues with halos and glare across a range of vision.
The lens moves mechanically to yield 1.0 diopter of monocular accommodation. Safety profile is good, as hinge of one billion cycles movement at ten cycles per second has been documented without degradation. Approximately 95% of visible light is transmitted. It transmits all light rays independent of pupil size. This aberration free aspheric lens allows great contrast sensitivity. Patients with astigmatism can tolerate this lens better. It also allows some torque without affecting vision. It should not be placed in the ciliary sulcus and should not be implanted if the bag is not intact or there is any zonular rupture.
Extended Depth of Field (EDOF) PIE
EDOF implants are in a class of their own. They resemble multifocal PI in appearance, but function on a different optic principle.
They increase the natural depth of field. It provides a continuous field of vision, though the range is not as extreme as in multifocal.
Symfony and Symfony Toric are the two contenders here. As you may have guessed from the names, Symphony Toric can also correct astigmatism. Hence, they find great use in eyes with astigmatism.
EDOF are used as an alternative to Crystalens in previously operated eyes. They can also be used when trying to replicate a person’s monovision and in amblyopic (lazy) eyes.
Symfony & Symfony Toric have a 13mm overall length with a 6mm optical zone. They have a biconvex, wave-front designed, anterior aspheric surface. The posterior achromatic diffractive surface is designed to reduce chromatic aberration which enhances the contrast of images. The echelette feature extends the range of vision. The toricity is added to the anterior surface of the Symfony toric implant.
It is important point to note, unlike other multifocal lenses, Symfony does not have different foci for distance, middle or near, but a continuous range of vision. It has frosted, continuous 360-degree posterior square edges. There are no glistening’s associated with this IOL material. The Symfony toric comes in 4 different powers.
Multifocal PI
Multifocal PI are truly bifocal but were labeled multifocal to distinguish them from bifocal glasses and contact lenses. Their mechanism of action is totally different than bifocal glasses.
In bifocal glasses the top segment is for distance and lower for near. These are refractive lenses. This method was tried in implants in the previous century but was not successful.
Multifocal PI can be either refractive or diffractive in construction. The refractive multifocals, like Array, have been discontinued. The diffractive multifocal implants have apodiazations (concentric rings of different heights) which split incoming light. They have a focal length for distance and one for near with an overlap for middle. One does not have to tilt their head to see near.
They are best for near and distance vision. Restor and Tecnis are the two lenses in this class.
Tecnis Multifocal
Tecnis is made of UV blocking hydrophobic acrylic. It is biconvex like a magnifying glass with diffractive rings on the posterior surface. It is manufactured in a proprietary diamond cryolathing process. It means the material and the shape are created in the same step.
Being clear, it transmits more light, but increased number of rings may cause glare. The near addition can be a +4 D which is optimized for those favoring near-vision activities like reading and knitting. It delivers tailored clarity at a theoretical reading distance of 33 cm. Plus 3.25 D is better for longer reading distances, such as reading newspapers. It delivers tailored clarity at a theoretical reading distance of 42 cm.
A +2.75 D is best for intermediate vision activities like computers. It delivers tailored clarity at a theoretical reading distance of 50 cm.
Tecnis Toric 11
The latest advancement corrects for astigmatism. Its sticky haptic technology prevents spinning or movement of the implant.
Restor
This acrylic IOL has a central optic and two arms, or haptics, for stabilization. It can be a one piece that is implanted into a bag or a three piece, which is implanted in the bag or ciliary sulcus.
The anterior apodised refractive optic that forms the diffractive zone is found within the central 3.6mm optic zone of the lens. It has nine concentric steps of decreasing heights allocating energy based on lighting conditions and activities. This lens does not require any ciliary muscle movement to function.
The +3.0 diopter on the lens yields a power on the cornea equal to wearing +2.5 readers, which allows for near vision. A refractive region that directs light to distal focal point surrounds the diffractive region. The asphencity of the optic compensates for the corneal spherical aberrations.
The chromophore filters blue light but clinically may impact color vision and the quality of distance vision. People with this lens require more light in dark conditions. There is a clear center zone for intermediate vision and peripheral clear zone for distance.
Restor Activefocus
This lens is a modification of Restor. The add power for near is only +2.5 D. The central clear zone is focused for distance instead of intermediate, so the patient gains intermediate vision at the expense of near vision.
Tecnis Multifocal Implant
Robin Gwyenne
“It is truly a miracle. I had been told multiple times there was no hope for my right eye after an orbital surgery. Dr. Khanna used his magic with Presbyopic Implant in eye and now I see 20/20 or better at all distances.”
Trifocal PI
Currently we have only Panoptix and astigmatism correcting Panoptix Toric. These PI have apodiazations or rings in their center similar to Restor multifocal. Optical engineers can modulate the height of the rings and distance between rings to design varying focal length for each zone.
The unique heights of the rings of this lens allow the incoming light to be split into three foci. One for distance, second for intermediate and third for near. This lens is great for people who devote most of their time to computers and intermediate vision, like financial analysts and computer programmers.
Panoptix Trifocal
This is a single piece biconvex lens with a central optic made of a high refractive index hydrophobic acrylic material. It is capable of being folded without damage prior to insertion through a smaller wound.
The central 6.0 mm optic has two haptics on either end, giving an overall lens diameter of 13 mm. In the central 4.5 mm of the optic there is a diffractive portion which divides the light to create +2.17 D intermediate (+1.65 D at cornea) and +3.25 D near (+2.35 D at cornea) add power. The front surface of the lens has negative spherical aberration to counteract the positive ones generated from the cornea.
Panoptix is actually a quadrifocal lens which has been modified to behave like a trifocal lens to improve distance vision. In simpler terms, it means it provides a more continuous field of vision.
It comes in two colors, yellow and white. The yellow color is blue light blocking and theoretically protects the macula. In real life, it affects the clarity of vision, especially in dim light. Hence, the clear Panotix model is preferred.
Panoptic trifocal
| Advantages | Disadvantages | |
| Crystalens | Clear vision for 2.5/3 zones. Works in post RK, post Lasik and early macular degeneration | May need glasses occasionally. Can develop Z syndrome. |
| Restor | Full range of vision (3/3) | Extra light for reading. Waxy distance. |
| Tecnis | Full range (3/3) | Initial glare & adjustment period for computers |
| Symfony | Stable lens. Clear vision for 2.5/3 zone. | Cobweb against lights |
| Symfony Toric | Can correct astigmatism | Susceptible to rotation which can change astigmatism |
| Panoptix | Best intermediate with full range | Material can develop glistenings |
| Panoptix Toric | Can correct astigmatism | Rotation less likely but can still affect result |
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| Restor | Tecnis | Crystalens | Symfony | Panoptix | |
| Far | Yes | Yes | Yes | Yes | Yes |
| Middle | Yes | Some issues | Yes | Yes | Best |
| Near | Yes | Yes | Arm’s length | Variable | Yes |
| Glare | Some | Most | Least | Cobwebs | Some |
| Extra light at night | Yes | No | No | No | No |
| Lens movement | No | No | Yes | Possible | No |
| Tolerate astigmatism | No | No | Yes | Yes | No |
| Tolerate Dry Eye | No | Better | Yes | Yes | No |
Comparing PIE Eye Surgery with other procedures that correct presbyopia:
LASIK for Reading or bifocal lasik by Presbyopia consultant surgeon
In certain individuals, under correcting one eye can help improve computer vision. If the dissimilarity in the end resultant powers is less than 1.5 D it is called blend vision. If the difference is exaggerated to 3 D it is termed monovision. In such cases, one eye is for near and cannot see far at all. The other eye sees far and cannot see near.
It sounds good in theory, but in reality, binocularity (or depth perception) is sacrificed, and intermediate vision may suffer as well. These extreme differences may not be well tolerated.
Only 20 % of people can function normally with monovision. Others may experience dizziness, “jump in” images, and confusion.
Before attempting blend vision or monovision, the capability to adapt should be tested thoroughly by trial frames in the office. Many patients also attempt a monovision contact lens trial for a few days at home and work. It has been customary to aim the dominant eye for distance and non-dominant for near.
It is wise to try to see if this pattern works best for the patient or if the opposite pattern is better. That is non dominant for distance and dominant for near.
In people older than 45, who have lost the ability to read at near, this change may be difficult.
Monovision Case Study
A 52-year-old restaurant owner with -3 D glasses decided to have Lasik eye surgery at a high-volume center. After the surgery he was very depressed. He could not see the cash register nor the menu which was his work for 10 hours a day. All that happened was he traded distance glasses for near glasses.
Lasik eye surgery is like fire, if used correctly it will display great outcomes. If used incorrectly, it can burn. The surgeon should use it judiciously.
The Advantages of PIE Eye Surgery vs. LASIK
Vision in all three zones is attained while retaining depth perception. To perform Lasik, a flap needs to be fashioned either by a femtosecond laser or microkeratome. The flap fashioned in Lasik has some drawbacks. It weakens the cornea and interferes with the corneal nerves.
Lasik cannot be performed on very thin corneas, or abnormally shaped corneas, for fear of causing the cornea to bulge forward. Damage to the central corneal nerves may induce dry eyes and make preexisting dryness worse. PIE can still be performed on such thin or dry corneas. Another advantage of PIE over Lasik is that the center of the cornea is not violated.
After Lasik the vision may change and worsen as the natural lens undergoes changes. A person would need to change glasses to see better at the particular distance the vision gets altered. Finally, after Lasik, when one develops cataracts, they would require cataract surgery. PIE prevents the fluctuation in vision and development of cataracts by removing the dysfunctional natural lens.
Lasik cannot be performed in high hyperopes, or farsighted people, more than 6 diopters. These numbers are not even approved by FDA. Similarly, people with extreme nearsightedness, above 10 diopters are not candidates for Lasik. In these situations, PIE triumphs over Lasik.
| Type of Procedure | PIE | Lasik |
|---|---|---|
| Zone of Vision | Distance & Middle & Near Vision | Distance or Middle or Near Vision |
| Duration | Permanently glasses free | Need for glasses by age 45 |
| Binocularity | Yes | No |
| Corrects Extreme Refractory Errors | Yes | No |
| Prevents Cataracts | Yes | No |
| Dry Eyes | Does not cause | Usually induces |
| Abnormal Cornea | Yes | No |
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Is PIE Eye Surgery possible after Lasik?
PIE can still be performed after a patient has already had Lasik. The accuracy of the implant needed for the procedure requires special calculations.
After the PIE procedure the flap may accumulate fluid and delay healing. A small optical zone created by the laser may interfere with the functioning of the implant. Of course, most patients are very happy to have PIE after Lasik. They wore glasses in their youth and Lasik freed them from the glasses. Having to wear glasses again is very frustrating for them.
In summary, PIE is more advantageous than Lasik for people above 45 and surely for those above 55. Thus, PIE has been termed as Lasik++.
