Toric lenses | Contact Lenses for Astigmatism | Benefits of TL

Toric Lenses & Astigmatism

 ( Will Contact Lenses  be a Solution or Not?)

Toric lenses are contact lenses are used to correct astigmatism; a refractive error in the eye caused by an imperfect curvature of the cornea. When light enters the eye, it is not focused properly on the retina, resulting in distortion. The most common symptoms of this condition are blurred vision, sensitivity to light, squinting, headaches and eye strain.

A common eye condition known as an astigmatism often goes undetected because of the minimal effect it has on a patient's vision. Some astigmatisms can lead to blurred or impaired vision if they become moderate or severe. The cause of the blurred and impaired vision is the result of the eye's cornea or lens having an irregular shape. In a normal eye the cornea has a circular shape, whereas corneas with an astigmatism have a longer oval shape.

There are many approaches to correcting astigmatism for the contact lens wearer. One of the most common approaches has been to ignore astigmatic error, applying spherical equivalent correction. This is a legitimate approach for low amounts of astigmatism or situations where simplicity and cost are of higher priority than acuity. Performance in sports such as soccer or hockey, for example, while requiring good vision, is not likely to suffer due to a visual acuity that is not a perfect 20/20.

The design of a toric lens ensures that the lens does not rotate in your eye if you blink or move your eyes. This is necessary as toric lenses contain two powers perpendicular to each other, one to correct the astigmatism (CYL/Cylinder) and the other to correct either short-sightedness or far-sightedness (SPH/Power).

The selection of toric lens parameters is steadily increasing year by year, most notably in the range of available cylinders for monthly replacement toric lenses and axis measurements for daily replacement, single use toric lenses and silicone hydrogel torics. The manufacturing process for toric lenses is more complex and this is reflected in higher prices compared to standard soft contact lenses.

Unlike spherical lenses, toric lenses are designed not to rotate on the eye. Continual exposure of the inferior front surface of the lens to drying during the inter-blink interval could lead to deposit formation but the surface technology applied to some silicone hydrogel lenses renders them highly deposit resistant, especially for protein. Despite this advantage, some silicone hydrogels have been prone to lipid deposition particularly when a surface treatment is not used.

Lipids can diffuse into the lens matrix and cannot be extracted by lens care solution surfactants, leading to regions of reduced lens wettability. This response can vary between individuals and while deposition of native tear film lipid is important for lens lubrication, a buildup of oxidized lipid deposits can be problematic, leading to contact lens discomfort and intolerance. The addition of a ‘rub and rinse’ step to the lens care regimen is important for these wearers, especially in non-surface treated lenses.

Toric Contact lenses Advantages & Disadvantages 

The advantages of a soft toric contact lens include easy adaptability, as comfort is usually quite good even initially. Other advantages of soft toric lenses include:

• Extended wear option –allowing up to thirty days of continuous (overnight) wear.
• Eye color –soft torics are available in various colors that can change even the darkest eyes to a variety of colors.
• Convenient replacement schedules –conventional lenses allow you keep the same lenses for a year, or the more common "disposable lenses' allow you to wear for one month, 2 weeks, or only once and throw away, with no need to ever clean them.
• One of the chief benefits of fitting a toric lens is the improvement in vision over a spherical lens. Even for low levels of cylinder, the improvement can be significant. A three to 5.5 letter improvement in vision compared to the spherical equivalent or ‘masking’ was observed for low astigmats (≤1.00 DC) and 8.5 up to 12 letters of acuity improvement was observed in high astigmats (1.25 to 2.00 DC) when they were fitted with toric lenses rather than sphere (P<0.05). A one or two line improvement in visual acuity shows the visual benefits the practitioner can offer are significant, even for a low astigmat.

Their biggest disadvantage is the potential for fluctuating vision. No matter how good the lens design and fit, all soft toric lenses rotate and move a bit in the eye. As explained earlier, this can be a source of frustration when you can see clearly one minute, and are blurry the next. The more astigmatism a person has, the more likely he/she will be sensitive to the lens movement.

Conclusion

When choosing a toric lens, consider your patient's history, needs and demands in addition to optical and physical requirements. Previous contact lens wear experiences will also provide valuable clues to help you develop a successful contact lens program. Demands of perfect vision or perfect comfort, as well as occupational or athletic needs will guide you in your first decision: whether to proceed with a soft lens or a rigid lens.

Pink Eye Symptoms & Contact Lenses| Causes | How to treat

UnderStanding Pink Eye Symptoms & Contact Lenses

Pink eye, also known as conjunctivitis, is an inflammation of the conjunctiva. Conjunctivitis literally means "inflammation of the conjunctiva". The conjunctiva is a thin membrane containing tiny blood vessels and produces mucus to coat and lubricate the surface of your eye. When the conjunctiva becomes irritated or inflamed, the blood vessels become larger and more prominent, making your eye appear red.

Conjunctivitis may occur in one or both eyes. Conjunctivitis can cause swelling, itching, burning, discharge and redness of the protective membrane that lines the eyelids and covers exposed areas of the white of the eye.

The conjunctiva is a thin membrane that covers the whites of your eyes by coating it in a mucus to lubricate the surface, helping to protect it. Pink eye can be caused by a number of things from bacteria, viruses, allergies to other environmental irritants. Regardless of the cause it can be extremely contagious. Symptoms usually include red eye, itchiness, a scratching and/or burning feeling.

Different Causes of Pink Eye Symptoms

It occurs when our conjunctiva is inflamed due to infection. (If you're like me and don't know what conjunctiva means at first, it's the part where your eyeball and eyelids meet). The three most common forms of pink eye are viral, allergic and bacterial.

When this happens, your eyes appear red, watery and you also feel irritated. Sometimes, your eyes may feel itchy as well.

Causes of pink eye which, for contact lens wearers, can be:

• Use of extended wear contact lenses. Bacteria can build up underneath lenses that have been in the eye for long periods of time.
• Poor hygiene. Failure to wash hands properly before inserting or removing lenses, or laziness when it comes to changing your contact lens solution, can all cause eye infections, as bacteria gets into the eye and onto the lens. 
• Trying to save money by NOT changing disposable lenses after the required time period can also result in pink eye. This is as much due to eye irritation initially, but an itchy eye can soon become an infected one if you don't listen to your body and throw away those lenses as soon as your eyes begin to itch.
• Allergies can, of course, affect contact lens wearers who may be susceptible to high levels of pollen or a windy day may just blow grit into your eyes, resulting in red swollen eyes. 

How to treat Pink Eye Symptoms Naturally & Other Ways to treat it.

The best tip I can offer as a contact lens wearer for avoiding pink eye symptoms, is to ALWAYS change your disposable lenses according to the maximum wear time. Don't try and save money by wearing those daily disposables for an extra day or two or extend your 1 week lenses to 2 weeks.

• Put damp herbal teabags like chamomile or elder-flower (after they have been used to make tea) onto the eyelids and lie down for half an hour. 
• Place a tablespoon of chamomile flowers in a cup of boiling water, infuse the solution for 10 minutes, remove the petals, and then allow the solution to cool. It makes a great cooling eye-wash that really helps to relieve pink eye. 
• Soak some cotton wool pads in warm milk that has first been boiled to kill any bacteria that may be present. Pop them onto your eyelids and lie down for half an hour to let the compress soothe your eyes.

Only the bacterial causes of pink eye can be treated with antibiotics. If it is a bacterial irritant that has caused your symptoms there is usually puss present. Viral and other causes will most often clear up on their own without damaging your eyes, however it is always recommended to see an ophthalmologist to confirm your symptoms.

While severe bacterial forms of conjunctivitis or pink eye need to be treated with antibacterial eye creams or eye drops, sometimes, you just can't get to a chemist or an eye doctor, or your eyes may be so swollen and painful, you don't want to go out or you simply cannot drive.

Contact Lens Prescription | How to decode Eg -1.25 | Terminology

A contact lens prescription has a series of fields that are not included on your eyeglass prescription. These fields signify important aspects, like the curvature and depth of the contact, to ensure that your contact lenses fit and function properly. Eye doctors use standard terms, abbreviations and measurements to write contact lens prescriptions. It may look like a secret code, but it's really quite simple to decipher. The prescription may also have an expiration date, brand name, and other fields, but most of these are optional by the doctor. By using these universal terms to describe ocular imperfections, prescriptions can be interpreted by eye doctors around the world.

Understanding Contact Lens Prescription & Terminology Used in this Test 

Contact Lens Prescription

Eye: - Which eyes the prescription line item is for.

• OD - Right Eye 
• OS - Left Eye
• OU - Both Eyes
• R - indicates the right eye. Sometimes written as O.D. 
• L - indicates the left eye. Sometimes written as O.S. 

Brand: - The brand/type of contact lens that your doctor has fitted you for. In the United States, lens prescriptions always indicate a specific brand. The law states that US retailers must sell you that brand and no other. In the case of a “private label”, contact lenses that are sold only by eye care professionals, substitutions of an equivalent natural brand or private label brand may be permissible.

Power sign Either + (plus) or - (minus). Power, the diopter measurement needed to correct your vision.

Contact Lens Prescription Terminology

Sphere (Sph): - Sphere (this can also be referred to as Power or PWR), is a number between +20.00 and -20.00. Plano means the lens has no optical power and does not correct vision. The number might be very small, like 0.25, or a large number, like 6.00. The higher the number, the stronger the prescription lenses required. This can influence your choice of frames. The higher the prescription, the greater the curve of the lens needed.

Cylinder (CYL): - It is a number between -0.50 and -4.00 and is only found in Toric Prescriptions to correct astigmatism. Measured in diopters, the cylinder shows the extent of your astigmatism. A negative sign means Myopia (nearsightedness) astigmatism and a plus sign means Hyperopia (farsightedness) astigmatism.

Axis (Axis): - is a number between 1 and 180 and is only found in Toric Prescriptions to correct astigmatism. The axis is measured in degrees and indicates the orientation of the cylinder in the lens and is used in order to compensate for the cornea’s oval, rather than round, shape. The number is not related to how well you can see but it helps the lab know what angle to position your lenses in the frame.
Often the Sphere , Cylinder and Axis of prescriptions will be written all together in the following form: SPH / CYL x AXIS and will look something like -1.00/-0.75 x 90.

ADD: - is a number between +0.50 and +4.00 only found in Bifocal or Multifocal lens prescriptions. If you are over 45, there may be a number where it says ‘ADD’. This is your reading addition and relates to the amount of additional correction needed to focus at close distances. If a measurement is shown in this section, it means you have different prescriptions for distance and reading. Bifocal or varifocal lenses may be needed.

Base Curve (BC): - Curve (usually a number between 8 and 10), Number between 7.0 and 9.5 which determines the looseness or tightness of a contact lens. It’s the back curvature of your contact lens and is measured in millimeters. For best fit, comfort and eye health it’s prescribed to match or complement the curvature of you cornea. The lower the number, the steeper your cornea.

Diameter (DIA): - Diameter (usually a number between 13 and 15), Number between 13.0 and 15.0 and is the diameter of the contact lens. It’s the distance, measured in millimeters, from one edge of your contact lens to the other edge. It’s important because it determines where on your eye the edges of the lens will rest. If the diameter is wrong, it can cause irritation and/or abrasions.

Lens Tinting: - This is the tint or colour of the contact lens. Some lenses are clear and most have a very light tint called a visitant which allows you to see the contact lens slightly more easily when handling it. Tinted contact lenses have a variety of colors to choose from to change your natural eye colour.

Conclusion

As we know a contact lens is a thin lens, made of flexible or rigid plastic, that is placed directly on to the eye to correct vision, used as an alternative to spectacles, or, if colored, to change one's eye color cosmetically. It is a corrective, cosmetic, or therapeutic lens usually placed on the cornea of the eye.

Contact lenses are more versatile than glasses making it easier to participate in a number of outdoor activities and sports such as jogging, golf, tennis, skiing or skating. By wearing contact lenses you now have the option of choosing from a variety of non-prescription sunglasses for sport and fashion.

Your doctor will recommend the best contact lenses for your eyes based on a complete eye examination and a review of your visual needs both at work and play. Success with contact lenses depends upon a certain amount of motivation and a commitment on your part. You must learn to take proper care of both the lenses and your eyes.

 

Contact Lenses Prescription (-1.25 ) | What & Why it is Needed?

Understanding Contact Lenses & Eye Glass Prescription 

Prescriptions last one to two years, depending on the minimum required by state law and even though prescriptions for contact lenses and glasses are similar, they should never be used for one another. Once your prescription has expired, you must be refitted to gain a new prescription, and to be able to purchase new lenses. Your contact lens prescription contains specific information to ensure your contact lenses are safe, comfortable and provide optimum vision.

If you're in the U.S., your contact lens prescription is yours to keep. In fact, by law your eye care practitioner must give you a copy of your prescription at the conclusion of your contact lens exam and fitting — even if you don't ask for it.


If an eye care practitioner is seeing a patient for the first time, vision is usually checked without any correction and this is noted in the chart. Next, refraction is performed. A refraction is the process of determining one’s glasses (or contact lens) prescription, which is typically completed as the patient looks through a device known as the phoropter. Once you've been properly fitted by your eye doctor and have a valid contact lens prescription, you have the option of buying contact lenses from a wide variety of sources.

Is Contact Lens Prescription is Different from eyeglass prescription?

How do you read a contact lens prescription? Your contact lens prescription is significantly different from your eyeglass prescription. Although some of the numbers and measurements are the same, a contact lens prescription has a series of fields that are not included on your eyeglass prescription. In addition to the lens power, your contact lens prescription contains several other pieces of information related to the size of the lens. These fields signify important aspects, like the curvature and depth of the contact, to ensure that your contact lenses fit and function properly. For this reason, your eyeglass prescription cannot substitute for your contact lens prescription, and vice versa.

Why one should take precaution in case of Contact Lenses?

A contact lens is a medical device, and a poorly fitted lens — or one made from a material not well-suited to your eyes — can cause distorted vision, discomfort, infection, inflammation, swelling and abrasion. In rare cases, permanent eye tissue damage could result. And it goes without saying that you should never share your contact lenses, including colored contacts and theatrical contacts. Sharing contact lenses can cause potentially sight-threatening eye problems.

Remember, if you're diagnosed with a lens-related problem, it's unlikely that you'll have to permanently discontinue wearing contacts. Chances are you'll simply need a different size, material or design of lens. Wherever you choose to purchase your contact lenses, always make sure you buy your contacts from a legitimate source.

Read Here >>> Contact Lens Rule - Federal Trade Commission

Contact Lenses | Benefits | Uses | What is It?

Contact Lenses

Contact lenses are closer to natural sight than eyeglasses. They move with your eye and correct the refractive error closer to the eye to allow for a more natural field of vision. They don't get in the way of your line of sight, like glasses can. Contact lenses can be worn all day, or even several weeks at a time, so you don't have to worry about putting them on and taking them off.

What is the Principal Behind Contact Lenses

The principles of refraction and related to optics are similarly applied to contact lenses. This contains the correction of current defect by replacing the contact lens surface with corneal curvature which accured in accordance with the degree of myopia and hypermetropia. Since the major part of astigmatic defects develop due to the distortion of frontal layer of cornea, either hard or special soft lenses produced only for astigmatism shall be used. 

Cases In which Contact Lenses are Used

Farsightedness / Hyperopia: -  People with hyperopia can see clearly far away, but their close-up vision is blurry. To correct hyperopia, the lens is thicker at the center and thinner at the edges. These lenses are called plus, or convex. The lens bends the light toward the center and moves the focal point back so that light is focused on, rather than behind, the retina.

2 Types of Contact Lenses

• The Gas permeable hard lenses
• Soft Lenses   

Contact lenses are not one-size-fits-all, and constant "lens awareness" could indicate a poorly fitting lens. Lenses come in thousands of combinations of diameter and curvature. If your lenses have the wrong diameter or curve, you'll likely feel that something is always in your eye. If the lenses are too large, your eyelids will tend to dislodge them when you blink. The wrong size lenses can even cause abrasion of your cornea.

Wearing contact lenses should be a comfortable alternative to wearing regular glasses to aid in improving vision.  Yet sometimes people don't receive the desired benefits of wearing contact lenses.  So Make sure you are not getting any problem after wearing Contact lenses.