Wednesday 20 July 2016

AN AWESOME COMPARISON OF KERATOCONUS CONTACT LENSES BASED ON VARIOUS PARAMETERS

Introduction of keratoconus disease:

The literal meaning of keratoconus is ‘conical cornea’ or ‘cornea cone’. Cornea is the front part of eye acting as a transparent window to the eye. It is normally clear, transparent and round shaped. When light enters through the healthy cornea, it gets refracted properly but when someone suffers from keratoconus eye disease, the cornea becomes thin and bulges outwards in cone shape.
Due to this corneal thinning, cornea becomes irregular and cone shaped losing the normal round shape. Keratoconus can also be defined as irregular astigmatism, since in keratoconus cornea becomes irregular in shape.
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Because of the keratoconus eye disease, it becomes difficult for the light rays to focus properly on the retina, as the corneal surface distorts and acquires the shape of a cone.
This eye condition is known as the keratoconus. Keratoconus is a degenerative eye disease, if left untreated can ultimately lead to corneal transplant.
Patients suffering from keratoconus eye disease can use eye glasses or soft contact lenses only if their keratoconus is in very initial stage. But as this corneal disease worsens, it becomes difficult to acquire good vision by using eye glasses or soft contact lenses.
Since with the progression of the keratoconus the cornea becomes more conical in shape, therefore eye glasses or soft contact lenses cannot provide satisfactory vision any more.
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Therefore at higher stage of the keratoconus, especially designed contact lenses have to be used for keratoconus. Single type of contact lens cannot be used by all keratoconus patients. The best contact lens is chosen out of many types available, depending on quality of vision, comfort and fitting.

Let me help you in choosing the most suitable contact lens for you

How big these contact lenses are and how do they look like...

The following image displays various contact lenses for keratoconus along with their real sizes...



Comparative sizes of contact lenses
Image by:
www.eye.hk

What is the quality of vision obtained...

·      RGP contact lens
The rigid material of the rigid gas permeable contact lens (RGP contact lens) forms an artificial smooth surface over the irregular conical cornea. Because of this regular smooth surface of the cornea the best possible quality of vision is obtained.
·      Scleral contact lens
Vision quality obtained by the scleral contact lens is excellent as the tears filled vault over the cornea fills the irregularities of the corneal surface thus provides good quality vision for the keratoconus patients.
·      Hybrid contact lens
The quality of vision is comparable to RGP contact lens since the hybrid contact lens has RGP center which hides cone of the cornea to offer clear vision.
·      Soft contact lens
Quality of vision obtained by soft contact lens for keratoconic cornea is not satisfactory as it takes shape the conical cornea.


How comfortable the contact lens wearing is...

·      RGP contact lens
Rigid gas permeable contact lens is rigid in nature. Rigid contact lens should not be confused with hard contact lenses. RGP contact lens is not as hard as hard contact lenses, but still quite uncomfortable to wear. 
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Therefore this contact lens requires some time for adaptation. Due to its small size, RGP contact lens moves over the cornea with each blink. So if any dust particle gets trapped between the contact lens and cornea, it can be intolerable. In that case it may be required to reinsert the lenses after removing them.
·      Scleral contact lens
Scleral contact lens provides excellent wearing comfort. This lens has very large size, so it rests on the sclera (white part of the eye) which is comparatively less sensitive part of the eye. Not only this, scleral contact lens also creates a tear filled vault over the cornea which further adds to more comfort in wearing.
·      Hybrid contact lens
Quite comfortable in wearing as the outer skirt of the hybrid contact lens is made soft like soft contact lens.
·      Soft contact lens
Wearing comfort is excellent as the whole lens is made of soft material as obvious by its name.


Who is the right candidate for these lenses...

·      RGP contact lens
RGP contact lens is generally recommended for mild and moderate stages of keratoconus. It cannot be used for advanced keratoconus because in that case the cornea becomes too steep to hold the lens. RGP lenses are also used for astigmatism, presbyopia and Orthokeratology (ortho-k). Ortho-k is a technique where specially designed gas permeable (GP) contact lens is worn overnight while sleeping. This helps in reshaping the cornea to get clear vision for two to three days approximately without any contact lens.
·      Scleral contact lens
Scleral lenses are particularly used for advanced stage of the keratoconus. Other eye problems where scleral lens can be useful are- severe dry eyes, corneal ectasia, microphthalmia, stevens-johnson syndrome, sjogren’s syndrome, aniridia, neurotrophic keratitis, post-LASIK complications, post corneal transplant, pellucid degeneration and some chemical and burn eye injuries.
·      Hybrid contact lens
Hybrid lenses are used when RGP contact lens becomes intolerable to wear. In that case hybrid contact lenses can be very helpful as they have soft outer skirt which makes wearing contact lenses comfortable.
·      Soft contact lens
Soft contact lens can offer good quality of vision only in initial stage of the keratoconus, as on using soft contact lens for advanced keratoconus it takes shape of the highly irregular cornea due to its softness.
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Although soft contact lens can be very comfortable to wear but to get good quality of vision for advanced keratoconus, you must switch to other options like RGP, scleral or hybrid contact lenses.


How much difficult it is to insert and remove these lenses...

·      RGP contact lens
In case of RGP, putting in and removing contact lenses is easy due to their small sizes. But this small size also makes it more susceptible to lose it in the eye or on the floor.
·      Scleral contact lens
Due to their very large sizes, putting in contact lenses is very cumbersome also removing contact lenses too require some skills. While putting in contact lenses into the eyes, these are overfilled with a sterile saline solution, so that no bubble gets trapped under the lenses.
·      Hybrid contact lens
It’s not that cumbersome to put in and remove the lenses from the eyes as compared to scleral lenses but requires more skills as compared to RGP.
·      Soft contact lenses
Little bit difficult to insert and remove the lenses because of its large size.


What material is used for their manufacturing...

·      RGP contact lens
RGP contact lens is made up of oxygen-permeable polymers. As we know gas permeability is essential in contact lenses for good health of the eyes.
·      Scleral contact lens
Scleral contact lens too is made up of a highly oxygen permeable polymer which is good for corneal health.
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·      Hybrid contact lens
Material used to manufacture its central part is same as that of RGP (oxygen permeable polymer) while the outer skirt is soft like soft contact lens, made up of silicone hydrogel or regular hydrogel soft lens material.
·      Soft contact lens
Material of soft contact lens is silicone hydrogel or regular hydrogel.


Ease of handling these lenses…

·      RGP contact lens
Handling of RGP lenses is very easy. These are rough and tough lenses. The rigid material protects it from any scratches. These are so hard that they can be broken by applying enough pressure.
·      Scleral contact lens
It is not easy to handle scleral lenses because of their soft material and large size. They are more delicate as compared to RGP.
·      Hybrid contact lens
Care is required while handling these lenses since the central part of the lens is RGP which is rough and tough but the outer skirt of the hybrid contact lens is soft. So on handling carelessly, there is some possibility of tearing of the outer skirt of the lens.
·      Soft contact lens
Soft contact lens too requires great care in handling because of the soft material. Large size makes them difficult to insert and remove.


What are the other popular names for these lenses...

·      RGP contact lens
RGP contact lens is also known as GP lens, rigid gas permeable lens and oxygen permeable lens.
·      Scleral contact lens
Scleral contact lenses are also famous by the name ‘ocular surface prostheses’.
·      Hybrid contact lens
Hybrid contact lens is the combination of RGP and soft contact lens, so popular name is hybrid contact lens itself. 
·      Soft contact lens
Soft contact lenses are also known as silicone hydrogel lenses after the name of its material of manufacturing.
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What is the maintenance cost...

·      RGP contact lens
RGP contact lens maintenance cost is quite low as they are rigid. They require comparatively less caring and their cost is also low. Because of their long life you don’t need to spend money on lens replacements frequently.
·      Scleral contact lens
Scleral lenses are very costly and are recommended generally for advanced stages of keratoconus and other various eye problems. Their maintenance cost and skill required to use them is significantly higher than RGP lenses. Consumption of contact lens solution is very high as very large sized scleral lens needs to be filled completely with the solution while inserting, so that no bubble gets trapped under the lens.
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·      Hybrid contact lens
Hybrid contact lenses too are very expensive to buy and maintain as compared to RGP contact lenses. As the outer skirt of the lens is soft but central part is rigid so there are chances of tearing and separation of the outer skirt from the central rigid part after long time use. This reduces the life of the lens and need arises to buy new pair soon.
·      Soft contact lens
Soft contact lens requires more caring because of its delicacy and softness. Soft contact lens has short life so needs to be replaced frequently. 

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