Contact Lenses Comprehensive Guide: Types, Comparison, Advantages, and More

Using contact lenses? Do you have questions related to contacts? Taking a peek at the following detailed information about contacts can give you a window into the world of contact lenses. 

So, without further ado, let’s jump into the topic.

wearing-contact-lenses
Photo: Wikipedia CC BY 3.0

What are contact lenses?

Contact lenses, or simply contacts, are thin, light-weight corrective, therapeutic, or cosmetic devices designed to fit over the cornea (the clear outer layer of the eye). Similar to eyeglasses, contact lenses correct the ametropia (myopia, hyperopia, astigmatism, presbyopia) by adding or subtracting the total refracting power of the eyes. 

 

Over 150 millions people now use contact lenses worldwide. Likewise, in the United States alone, over 24 million people wear contact lenses.

 

Contacts, if used with care and proper guidance, provide an effective and safe way to correct vision. These are boon for nearly anyone who wishes to have corrected vision without the hassle of eyeglasses or cost and complications of LASIK surgery. 

Eyeglasses vs Contacts

glasses-vs-contact-lenses

People prefer to use contact lenses for numerous reasons. In most cases, aesthetics and cosmetics are the major determining factors for choosing contacts over spectacles. 

The other important reason for this is that the contact lenses provide wider peripheral vision because they rest at a closer distance than do by eyeglasses. Similarly, contacts are preferred for sports, or other outdoor activities as they are not affected by moisture or perspiration. 

Contact lens wearer can also enjoy the benefits of goggles or protective sunglasses without any prescription. Meanwhile, there are some ocular conditions like aniseikonia and keratoconus in which contacts provide better vision than with glasses.

Who Invented Contact Lens? A Brief History of Contacts

The following timeline depicts the important landmarks in the development of contact lenses 

  • 1508: Leonardo da Vinci through his book Codex of the eye, Manual described a method of altering the power of the cornea by either submerging the head in water or placing a water-filled glass over the eye
  • 1801: Thomas Young made a pair of basic contacts based on Descartes’ model
  • 1845: Sir John Herschel proposed two ideas of refractive error correction: the first “a spherical bag filled with animal jelly”, and the second “mold of the cornea” that could be impressed on “some transparent medium”
  • 1887: Louis J. Girard invented a scleral contact lens
  • 1930: Development of Polymethyl methacrylate (PMMA)
  • 1936: Optometrist William feinbloom fabricated hybrid lens composed of glass and plastic
  • 1939: Hungarian Optometrist Dr. István Györffy produced first fully plastic contact lens
  • 1940: German optometrist Heinrich Wöhlk produced distinct version of plastic lenses based on his own experiments
  • 1949: Corneal lens was developed for the first time
  • 1959: Czech chemists Otto Wichterle and Drahoslav Lím published their work about soft contact lens in the book “Hydrophilic gels for biological use”
  • 1964: Lyndon Baines Johnson, US President, became the first President in the history to appear in public wearing contacts
  • 1971: First approval of the Soflens material by the US Food and Drug Administration (FDA)
  • By the end of the 1970s and through the 1980s and 1990s, a range of RGP materials was developed



Types of Contact Lenses

Based on the type of material they are made up, there are following contact lens types:

Soft Contact Lenses

These are mostly prescribed contact lenses in the world and are made up of hydrogel; gel-like, water-containing plastics. These are very thin and pliable so they conform perfectly to the cornea.

Soft contact lenses are more popular than hard contact lenses because they are immediately comfortable to the wearer. While PMMA (hard lens) takes around 2 weeks to adapt, the wearer of the soft lens feels comfortable immediately.

Based on wearing modality, soft lenses are categorized as follow:

daily-contacts-vs-monthly-contacts
Source: Contact Lens Spectrum January 2020
  • Daily disposable contact lenses

These are the most eye-friendly contact lenses as there is a lower risk of infection compared to other wearing modalities. Lenses should be disposed of daily.

Compared to other contacts, daily disposable lenses are generally more expensive.  

  • Extended (Overnight) wear contact lenses

Is it bad to sleep with contacts in? Well, some contacts can be worn for up to 7 days or 30 days continuously, also while you sleep.

These types of contact lenses, however, can cause complications like protein and lipid buildup underneath the lenses and serious ocular infections.

You are not going to have contact lens blindness, but there is still a risk of having contact lens problems if you sleep with contacts in.

  • Bi-weekly or monthly contact lenses

Bi-weekly disposable contacts and monthly contacts are prescribed as daily wear contacts and occasionally as extended wear contacts.

  • Yearly contact lenses

Yearly disposable contacts are also available in the market due to cheap prices and large parameter ranges. It’s better not to go for annual contacts if you are not good at care, handling, and cleanliness.

  • Toric contact lenses

These are the best contact lenses for astigmatism correction. Toric colored contact lenses for astigmatism correction as well as for cosmetic purposes are popular these days.

  • Bifocal or multifocal contact lenses

Although not suitable for everyone, these are boons for presbyopic persons. Multifocal contacts are useful for near and distance correction at the same time. 

Silicone Hydrogel Lenses

These are the latest products in the contact lens market. Recently, the focus has turned to a silicone-based plastic material that allows more oxygen to pass through lenses to the cornea.

There are popular brands which are producing silicone hydrogel lenses. Some of the popular brands are Acuvue Oasys, Air Optix Aqua, Biofinity, Purevision2, and others. 

The most frequently prescribed soft contact lens replacement schedule worldwide in 2019 was daily (45 percent), followed by monthly (39 percent), every one to two weeks (13 percent), every 3-6 monthly (3 percent) and annually (1 percent).Source

RGP (Rigid Gas Permeable) Lenses or Hard Contact Lenses

The other names of gas-permeable lenses are RGPs (Rigid Gas Permeable) or “hard” lenses. These are made up of plastics combined with other materials like silicone and polymers (mostly fluoropolymer).

Polymers and silicone pass oxygen to the tear layer through the lenses hence called “gas permeable”. These lenses are most suitable for keratoconus and irregular corneal surfaces. 

 

contact-lenses-trend
Source: Contact Lens Spectrum January 2020



 

contacts-use-worldwide
Source: Contact Lens Spectrum January 2020

Scleral Contact Lenses

This is another category of popular contact lenses. Due to advancements in computer technology in contact lens designing and manufacturing, scleral contacts are designed so that they are incredibly comfortable.

These are suitable mostly for eyes with severe dryness, a large amount of astigmatism, irregular corneas, corneal deformity, and degeneration. 

Colored Contact Lenses

Colored contacts are the lenses tinted mostly for cosmesis and sometimes for therapeutic purposes. Recently red colored contacts are used to compensate color vision deficiency as tint enhances color perception.

Orthokeratology (Ortho-K lenses) 

These are the special RGP lenses designed to wear while you sleep to temporarily alter the corneal curvature. This altered cornea corrects the refractive error temporarily while you’re awake. 

Bandage Contact Lenses

These therapeutic contact lenses are not prescribed for refractive error correction, rather these are used to cover the surface of the injured cornea to aid in healing and to minimize severe pain associated with the injured cornea. 

Advantages and Disadvantages of Contact Lenses

RGP or Hard lenses

Advantages of RGP “hard” contact lenses

  • Excellent vision as it corrects most vision problems
  • Easy to put on, remove and handle
  • Relatively long life-span
  • Available in large parameter ranges and handling tint
  • Best for myopia control and orthokeratology

Disadvantages of RGP “hard” contact lenses

  • Take time for adaptation
  • Can fall off easily from the center of the eye if the wrong parameter is used and sometimes even with the correct parameter
  • Debris gets accumulated underneath the lenses
  • Require regular follow-up care

Soft lenses


Advantages of Soft Contacts

  • Very short adaptation time
  • More comfortable compared to RGP lenses
  • Available with a handling tint
  • Available in various wearing modality like daily disposable, bi-weekly or monthly disposable
  • The best choice for an active lifestyle and sports activities

Disadvantages of Soft Contact lenses

  • Fail to correct all refractive errors
  • Vision may not be as clear as with RGP in the astigmatic and irregular cornea
  • Require regular follow-up care
  • Lenses wear out easily and must be replaced regularly

How do I get contact lenses?

The first and foremost step towards using a contact lens is to get an eye test by a qualified optometrist to determine whether your eyes are suitable for contacts or not.

If the optometrist recommends contact lenses to you, then you have to be clear about what you want your lenses for. This gives an idea to him to choose the best contact lenses for your eyes.

Similarly, he has to suggest an appropriate lens care product including contact lens solution and eye drops.

You have to go for several lens trials until you get the best fit. So, if you feel uncomfortable with the lens you can tell him so that he can choose you the next option.

It is normal to have slight discomfort at an initial couple of minutes but that should be gone by next few minutes.

Are contact lenses for you?

Whether or not contacts are a good choice for you depends on various factors. If you are switching from glasses to contacts keep the following points in mind.

  • Level of patience and motivation. High motivation is key to success from the initial days to the entire wearing period
  • Needs and expectations of the individual
  • Strictly following guidelines regarding wearing schedule, disinfecting, and cleaning
  • Proper diagnosis and treatment of conditions that may discourage contact lens wear
  • Can I wear contact lenses with astigmatism? Well, in the irregular cornea or high astigmatism, contact lenses provide the best vision than with eyeglasses

Who cannot wear contact lenses?

cannot-use-contacts

Certain conditions might keep people from wearing contacts. These include:

  • severe ocular allergy
  • frequent redness of eye and infection
  • dry eye (inadequate and improper tear layer)
  • the very dusty and dirty work environment
  • inability to take care of lenses properly



How to put contacts in?

Wearing contact lenses for the first time? If so, you might be wondering “how to wear contact lenses?” “how to put in contacts easily?”. Then don’t worry. Here are the basic steps to safely and successfully put contact lenses in your eyes:

  • Wash hands thoroughly with soap (without added oil or fragrances as they stick to the surface of lenses) 
  • Try to loosen the contacts if it is attached to the container by gently shaking the storage. Use fingertips (without long nail) to remove the lens from the storage
  • Rinse the lens thoroughly with the solution and never use tap water to clean the lens
  • Place the contacts on the tip of the index finger of the dominant hand (your active hand which you use for writing). Make sure the lens is free from scratches and damaged areas
  • Also, remember to check if the lens is right-side-out or not. If the lens is of bowel shape and the edge turns up, it is the right shape and be ready to put the lens inside your eye. If the lens is edge-tun-out, it needs to be reversed
  • Look straight to the mirror and hold the upper eyelid open with a non-dominant hand. Likewise, use the remaining fingers of your dominant hand to hold the lower eyelid open
  • Slowly move the lens towards the eye until it touches the cornea and the cornea will pull the lens immediately
  • Close your eyes for some seconds and roll them in a full circle slowly. Then open your eye and gently blinks 3-4 times.
  • Make sure the lens is placed correctly at the center of the eye by looking in the mirror and checking vision by alternately covering right and left eyes and comparing the clarity of objects

How to get contact lenses out

It’s really easier to remove contact lenses from the eyes compared to put in. First of all, wash, rinse, and dry your hands, then follow the given steps:

  • Look up and pull down and hold lower eyelid with your middle finger
  • Hold upper eyelids by fingers of non-dominant hand (you can skip this step after you get used to lens insertion and removal processes)
  • Pinch the lens between your thumb and index finger and remove it from the eye
  • Rinse and clean the lens with a solution and put in the lens case half-filled with solution then tighten the lid

Contact lens complications

Although contacts are generally safe for eyes, complications sometimes may occur. Around 5% of wearers get complications annually.

These complications are mostly the consequences of improper use. The anterior parts of eyes like the eyelid, conjunctiva, and cornea are affected by the improper use of contact lenses.

It is found that the major cause of contact lens complications is to sleep with contacts not designed for extended wear.

How to fix dry eyes with contacts?

A plethora of contact lens users are familiar with dry eye or contact lens-induced dry eye (CLIDE), as it is known. Dryness, irritation, and fatigue are the symptoms of CLIDE.

Luckily, when there is a problem there is a solution. It is recommended to have one free lens day a week, if possible. It helps the eyes to return to normal function in one day.

The most important factor hidden in the lens that determines the dryness of the eye is the water content of the lens. The higher the water content more moisture is absorbed by the lens from the eye via osmosis as they lose water during wear. So, low water content lenses are good for dry eyes.

Another best option is the silicone hydrogel lens. Silicone allows more oxygen to pass to the eye, which is vital for maintaining healthy natural tears and also maintaining a low water content of the lens.

It’s worth consulting an optometrist about the type of lens and re-wetting drops for dry eyes you should be wearing which might help to fight against dry eyes.

Allergies and contact lenses

Allergies are common in a few people when using contact lenses. Eyes are really sensitive to allergens. So, if you experience seasonal allergies, animal allergies, or even food allergies, the eyes are the first organ that shows symptoms of allergy.

Is there any possible way to deal with allergies when you use contacts? Here are some points to be followed to mitigate the effect of allergies while using contacts.

  • If you are planning to visit places full of pollen or other forms of allergens, wear sunglasses. Large-sized sunglasses act as a barrier to allergens floating in the air to reach your eyes.
  • Daily disposable lenses are preferred over other lenses during allergy season. Otherwise plan to disinfect your lenses every night as accumulated allergens can affect your eyes next time when you use.
  • Always use anti-allergic eye drops and re-wetting eye drops prescribed by your optometrist, mostly during allergy season.
  • Be prepared to use spare eyeglasses if your eyes turn red or start itching due to allergy.



How to avoid contact lens complications?

Contact lenses sometimes cause various problems ranging from slight discomfort to severe allergies and infections. To avoid such problems, contact users must be aware of these points:

  • Good hygiene: before touching and handling lenses, wash your hands thoroughly with soap and water. Let the wet hands air-dry or use a lint-free towel to dry them.
  • Good contact lens solutions: always use trusted commercial products, specifically designed for particular contact lenses materials. Don’t forget to replace solutions every time you use contacts. Likewise, gently rub and rinse lenses as explained by eye care practitioners. Lastly, check the expiry date of solutions as date expired solutions damage contact lenses.
  • No contact with water: always remember to remove contact lenses before swimming or using a bathtub. It’s not good to wash your face with contacts inside your eye.
  • Care of contact lens case: use sterile lens solution to clean the case. If you have to use soap water to clean the case don’t forget to air-dry the case before use.
  • Contact lenses replacement: contacts should be replaced regularly based on manufacturer guidelines. Do not use lens beyond its expiry date.
  • Do not share your contacts with someone else
  • Say NO to over-the-counter contacts: contacts should be used based on custom parameters. So, over the counter contact lenses can cause eye injuries and infections.
  • If you wish to get decorative or colored contact lenses, talk to your optometrist.
  • Avoid taking a nap or sleep with contact lenses inside your eyes.

For some people, dryness is the biggest issue in contact lens use. If your eyes get red, irritated, or inflamed, remove the contacts and use lubricating eye drops prescribed by your doctor.

Also, if you have blurred vision or you experience extreme pain or sensitivity to light, remove contacts and visit the eye doctor for medical intervention.

Buying contact lenses online?

After you get your prescription from an optometrist you can buy replacement contacts at many places. These days buying contact lenses online is gaining popularity. 

Hubble ContactsWalmart ContactsLenscrafters are among many best places to buy contacts online in 2020 in the USA.

Ocular health should be the main concern before practicing anything. Collect information about contact lenses and choose an optometrist who is knowledgeable and well experienced with contact lenses.  

Continuing to follow up appointments at regular intervals is essential in maintaining a healthy eye and clear vision.
The Future of contact lenses: How are they going to change over the next fifty years?

With the invention and manufacturing of new and better contact lens materials, contact lenses will become thinner and more comfortable. It means contacts will be barely noticeable in the eyes. We could see a trend of more people moving away from eyeglasses to contacts.

According to a plan launched by Google in 2014, they will be manufacturing a contact lens capable of measuring the glucose level in diabetic tears in the near future.

Although it has not come yet, its presence will be really exciting for anyone with diabetes. So, we can wait to see dual-purpose contacts in the future.

Telescopic lenses, bionic lenses, and lenses intended to deliver prescribed drugs are all being studied and researched. As new polymers are on the horizon, these ambitious projects will be successful very soon.

The silver lining in the lens case can reduce contamination. So, it is being studied for commercial production.

Further, we could possibly see smart contact lenses that would be able to take photos and record videos in the future. It is said that companies like Sony and Samsung are already in work to produce smart contact lenses.

factsDid you know? 

  • Contacts from different brands aren’t the same thickness or water content
  • Leonardo da Vinci proposed the first idea of contact lenses in 1508 AD
  • During the 1800s Blown glass contacts were shaped using cadaver eyes and rabbit eyes as molds
  • Modern RGP lenses are based on the same design developed in 1979 AD
  • The earliest known movie to introduce the use of theatrical contact lenses was by the actor Lon Chaney in the 1926 film The Road to Mandalay to depict the effect of a character who had a blind eye.

Sources


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4 thoughts on “Contact Lenses Comprehensive Guide: Types, Comparison, Advantages, and More

  1. Lucie Hoeft says:

    Great article! Just loved it. Keep up your good work!

  2. Muzdan for Drugs and Medical Devices, Sana'a, Yemen. says:

    Best of wishes

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