القرنية المخروطية Keratoconus

What is Keratoconus?

Keratoconus is a disorder of the anterior surface of the eye (the cornea). In simple terms this means that the cornea becomes thinner causing the cornea to bulge from its normal round shape to a cone shape. This bulging interferes with a person's vision and can severely affect the way they see the world making simple tasks like reading, watching TV or driving very difficult. The distortion caused by keratoconus has been compared to viewing a street sign through your car windscreen during a driving rainstorm.

The progression of keratoconus is unpredictable but generally the condition progresses slowly and can cease at any stage. While keratoconus interferes with the clarity of a person's sight it rarely causes blindness and in its early stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. As the disorder progresses the degree of vision obtained through glasses becomes less acceptable and contact lenses often become the best method of correcting vision problems.

Most people can successfully manager their condition using special keratoconus contact lenses, however in a small number of cases where the cornea can no longer successfully be fitted with contact lenses, a corneal transplant may be needed.

Who gets Keratoconus?

The actual incidence of keratoconus is estimated to occur in 1 to 5 persons per 1,000 in the general population. Keratoconus is generally first diagnosed in young people at puberty or in their late teens but can also be first diagnosed in people in their 40's or 50's. Keratoconus has no known geographic, cultural or social pattern, however its incidence seems to be higher in isolated populations. With continuing improvements to diagnostic equipment and eye care practitioner training, more cases of keratoconus are being diagnosed.


Treatment for Keratoconus

In early stage keratoconus, distortion of vision can be treated using glasses to correct minor myopia (nearsightedness) and astigmatism caused by the condition. As keratoconus advances, gas permeable (GP) contact lenses are the first choice to correct vision. Most of the time, this is a permanent remedy.

The Rose K lens has a number of features that make it ideal for keratoconus and is internationally recognised as the leading lens for the treatment of keratoconus.

* The lenses are designed using complex computer models and manufactured on special computerized lathes.
* The complex geometry of Rose K lenses take into account the conical shape of the cornea in all stages of the condition.
* Lenses can be customised to suit each eye and can correct the myopia and astigmatism associated with the condition.
* Rose K lenses allow the cornea to 'breathe' oxygen directly through the lens material providing excellant health to the eye.
* The lenses are easy to insert, remove and clean.

As a result the entire lens fits better over the eye leading to better comfort and optimum visual acuity (sharpness) for patients. However due to the progressive nature of the condition, it is important that lenses are fitted with great care and reassessed at least annually by your eye care professional.


Keratoconus Support

We encourage Keratoconus patients to discuss their condition openly with their eye care practitioner. Ask questions and learn as much as you can about the condition as lack of knowledge often creates the most fear or anxiety.

It is also important that you talk freely about your condition with family, friends and employers to ensure they understand your condition. We also recommend you talk to other keratoconus patients. The mutual sharing of experiences can be very reassuring.

Importantly, keratoconus should not stop you from accomplishing your goals. People from all walks of life have experienced this disorder and succeeded!
Keratoconus Support Groups & Information

The National Keratoconus Foundation - USA [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

Provides information to keratoconus patients, newsletters and seminars and supports research into keratoconus.

UK Self Help & Support Group - [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

Provides information and support, information about the condition, treatment and discussion forum.

The Global Keratoconus Foundation - [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

Daily Strength - [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

Patient UK - [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

Contact Lens Spectrum - [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]



Frequently Asked Questions

I have Keratoconus, will I go blind?

No, Keratoconus is not a blinding condition, although vision is likely to progressively worsen. Keratoconus causes thinning and distortion of the cornea, which is the clear dome at the front of the eye. The cornea normally has a rounded dome-like shape, but in Keratoconus the thinned area bulges forward to produce a cone like protrusion. This results in distortion and reduced vision, blurred distance vision, glare, light sensitivity and distrubed night vision. However with the use of contact lenses, most Keratoconus patients can maintain good functional vision and a normal lifestyle.

I'm 15 and have just found out that I have Keratoconus. Is the cone very noticeable to other people?

The corneal changes in Keratoconus are so subtle that special instruments and training are required to see them. Except in the most advanced cases, it is virtually impossible for someone other than a doctor to tell that you have Keratoconus.

Is it possible for Keratoconus to simply get better and heal on its own or is it a permanent condition that can only degenerate?

Keratoconus either progresses or remains stable: it does not get better.

Is my Keratoconus going to get worse and how quickly will it change?

Keratoconus invariably does get worse in the majority of cases, however progression is difficult to predict. In some cases it changes very little from the time it is first diagnosed. In other cases progression occurs rapidly over a relatively short period of time. The younger the patient is when keratoconus first appears, however, the more chance there is that it will progress significantly, particularly during the teenage years. It is very important to control any allergies which affect the eye during this time, so that any eye rubbing can be avoided.

Keratoconus has been confirmed in my right eye. Will my left eye be affected also?

Keratoconus is bilateral (ie affects both eyes) in about 97% of all cases. Only about 3% of cases are truely unilateral. A topography or mapping of the cornea by your practitioner will nearly always show some steepening in the unaffected eye at the time of the first diagnosis of keratoconus, even though the vision at this stage in this eye may be unaffected. Frequently one eye will show symptoms before the other, and the degree of severity is normally worse in one eye and often remains this way.

Will certain activities, such as sports or long hours in front of the computer, hasten the progression of Keratoconus?

There is no evidence that any physical or visual activity has any affect on the progression of Keratoconus. The exception is eye rubbing where the trauma caused by eye rubbing can damage the cornea which may cause the condition to advance more rapidly.

Why is my vision sometimes more than "double"? I only have 2 eyes so where do the other images come from?

Multiple images can be caused by a disparity between the two eyes or from multiple refractive zones within the optical zone of just one eye. If you see double and it disappears when you close either eye, it is most likely a binocular problem caused by the two eyes not working together. The causes of this are many and some are potentially serious. Mulitple images in one eye occur more frequently in ocular surface diseases like Keratoconus or in diseases affecting the lens or iris of the eye. In Keratoconus, surface thinning can create multiple optical zones that individually focus the same image to different areas of the retina, thus creating the additional perceived multiple images. Contact lenses usually eliminate most of these problems.

What is the difference between Keratoconus and "Common Astigmatism"?

Astigmatism is a common condition where the curvature of one or more of the optical surfaces of the eye (the cornea and lens surfaces) are more "curved" in one direction than the other. In "regular" astigmatism the maximum and minmum powers of the cornea are aligned at 90 degrees to each other, while in "irregular astigmatism" they do not align. An egg is a good example of a surface with regular astigmatism, whereas an orange (sphere) is a good example of a surface which has no astigmatism. Keratoconus is a degenerative condition where the cornea thins in affected areas. This can lead to astigmatism - often regular at first but becoming increasingly irregular as the condition progresses. It is possible to correct regular astigmatism with glasses or soft contact lenses, however for irregular astigmatism, where the cornea can often have multiple curves (giving multiple focuses), it is impossible to correct these multiple focuses with spectacles or soft contact lenses.

What is the meaning of the numbers used to describe the degree of Astigmatism?

Astigmatism is measured in diopters (D), a standard optical measure. In simple terms, the diopter represents the reciprocal of the focal distance in metres. For example, a patient with 2 D of nearsightedness would have a far focal point of 1/2 metre. A patient with 4 D would have a focal length of 1/4 metres or 25cm. A patient with 1/2 D would have a focal point 2 metres in the distance. Many patients have between 0.25 and 2.00 D of astigmatism. Between 2.25 and 3.75 is less common but still seen. Much above that in a "normal" patient is unusual. Keratoconus and post-transplant patients can have up to 10 D of astigmatism or even more.

What is the best contact lens for Keratoconus?

There is no single lens type or brand that works for every Keratoconus patient. In the early stages, conventional soft lenses can work remarkably well. As Keratoconus progresses, gas permeable (GP) lense work best for the majority of patients. In other cases where tolerance of a GP lens is a problem, piggybacking a rigid lens over the top of a soft disposable lens, can in many cases improve the tolerance dramatically and provide successful contact lens wear. Unfortunately, contact lenses alone may not completely correct your vision. For some patients, spectacles worn over contact lenses or special lens designs may help. In some cases, corneal scarring or other problems may limit vision, and no amount of correction will be completely effective. Surgery may be the best choice when the vision obtained with a contact lens correction is inadequate.

Can I still wear soft lenses if I have Keratoconus?

Soft contact lenses may work well in early Keratoconus. In more advanced cases they will do no harm but they rarely provide adequate visual correction. GP contact lenses usually offer better vision correction for Keratoconus.

My friend wears soft contact lenses for her short sightedness. Why can't I wear soft lenses for my Keratoconus?

Unfortunately soft contact lenses very rarely provide the same standard of vision that GP lenses provide. By nature, soft lenses wrap around the cornea giving rise to that same optical issues (distorted vision) that the keratoconus cornea causes. A GP (rigid lens) provides a new optical surface for light entering the eye, so light can be focused back to a single point. However in some early cases of keratoconus where the corneal distortion is minimal, soft lenses can provide an acceptable standard of vision.

I am going on 58 and have just been diagnosed with Keratoconus. My doctor has recommended contact lenses but I've never worn them before and I'm worried that I may not be able to handle them at my age.

Give contact lenses a try. Handling lenses is far less difficult than you would imagine and the improvement in your vision is likely to be subtantial. Make sure that you find a contact lens specialist who is patient, and is willing to take the time needed to properly train you on how to remove and insert your contact lenses and how to care for them. With sufficient training it would be most unusual that lens handling would prevent you from being able to use contact lenses.

Can I take advantage of different brands of contact lens solutions and eye drops, depending on what's on sale?

Recently published research has shown significant incompatabilities between newer contact lens materials and some contact lens care products. The result is irritation and increased risk of more serious problems. Clearly, not all care products are the same. You should avoid problems by first checking with your contact lens specialist before switching lens care products.

Recently I have noticed a 'general fog' which affects my vision like my lens is not clean. This usually comes on after a few hours of contact lens wear. What would cause this?

Fogging can be caused by a build up of deposits on the surface of the contact lens, or by some physiological change to the cornea. If fogging occurs, always remove the lens, clean it with a GP cleaner such as Boston Intensive Cleaner, rewet the lens and reinsert it. If the fogging problem is resolved then this was obviously due to some build up on the lens surface. However if the fogging persists, then it is likely to be due to some change in the cornea such as oedema, where the cornea swells and becomes less transparent. In this case you should consult your contact lens fitter as soon as possible, to determine the cause of your symptoms.

Some GP Keratoconus lenses have abberration control incorporated into their design. Is this necessary and what advantages does this have over lenses that do not have abberation control?

The most common type of lens aberration is spherical aberration and it is caused by two lens surfaces not being parallel; the front surface of the lens being significantly flatter than the back surface. This causes light passing through different points on the lens to have different focal points onto the retina (back of the eye) and produces a 'ghost' image around the original image like a tv set that is not tuned properly. By subtly changing the curves on the surface of the lens a significant amount of the spherical aberration can be eliminated. The amount of spherical aberration produced is proportional to the lens power, so as keratoconus gets worse, the lens power also needs to increase and so does the spherical aberration. Keratoconus patients commonly require very high powers on their lenses to see well and therefore obtain significant benefit from having aberration control incorporated into their lenses. Rose K2 is an example of a lens which has aberration control. In a study in the USA, where a group of over 50 patients wore Rose K lenses both with and without aberration control, 100% reported their vision with Rose K2 to be the same or better than the original Rose K design which did not incorporate aberration control, and 75% of patients reported their vision with Rose K2 to be better or much better. Many patients gained at least one line of vision which is very significant.

I've had transplant surgery and I've been told to expect changes in my vision for many months. How long should it take for my eye to stabilize, and is the astigmatism likely to get better or worse as my eye continues to heal? Also, will I need contact lenses after surgery?

Healing and refractive results after transplant surgery vary tremendously from patient to patient making it difficult to predict results. There is also no way to know if a contact lens will be necessary until your eye is stable. In addition to contact lenses and glasses, several adjunctive surgical procedures can be performed to reduce post transplant astigmatism if needed. The majority of patients can obtain reasonable vision with spectacles, however for both eyes to work together to give good binocular vision, a contact lens is still often required.

Can I have LASIK?

No, Keratoconus is a corneal thinning condition and LASIK is a corneal thinning procedure. Surgically making a thin cornea thinner will weaken an already weak cornea and speed the progression of Keratoconus thereby worsening the condition.

My lenses become uncomfortable in aeroplane cabins. What can I do?

Ideally one would never wear any contact lenses in an aeroplane cabin because of the reduced oxygen available and the very low humidity. This is certainly not an ideal environment for contact lens wear. Both of these factors invariably lead to dryness, irritation, discomfort and subsequent reduced wearing time. However for the keratoconic patient, leaving the lenses out when flying is often not an option as their uncorrected vision is insufficient for them to manage. Therefore while flying, we recommend frequent (at least hourly) use of contact lens rewetting drops, removal of lenses if sleeping, and removal of the lenses even for short periods to clean and rewet the lens if this is a possible option. Also keep your body hydration levels to a maximum by drinking plenty of water and avoid alcohol and coffee, both of which cause dehydration.

Our special thanks to the National Keratoconus Foundation for providing much of the information contained on this page.

Caring For Your Lenses

General Instructions:

Always wash, rinse and dry your hands before handling your contact lenses. Hand creams (particularly the intensive creams) and make up are the most common reasons for Rose K lenses not wetting properly.

Always use fresh unexpired lens care solutions.

Do not use saliva or anything other than the recommended solutions for lubricating or re-wetting lenses. Do not put the lenses in your mouth.

To Store your Rose K Lenses:

Use the system of lens care recommended by your eye care practitioner and carefully follow instructions on the solution labelling. Different solutions cannot always be used together, and not all solutions are safe for use with all lenses.

Do not alternate or mix lens care systems unless indicated on solution labelling.

Always clean, rinse, disinfect and use enzyme cleaners according to the schedule prescibed by the eye care practitioner. The use of any cleaning solution does not substitute for disinfection.

NOTE: Some solutions may have more than one function, which will be indicated on the label. Always read the label on the solution bottle and follow the instructions.

Lenses should be cleaned, rinsed and disinfected each time they are removed. Cleaning and rinsing are necessary to remove mucus and film from the lens surface. This should be done as soon as the lenses are removed from the eye, and before they are stored in the lens case. Disinfecting is necessary to destroy harmful germs.

Clean one lens first (always the same lens first to avoid mixing the R and L lens), rinse the lens thoroughly with recommended saline or disinfecting solution to remove the cleaning solution, mucus and film from the lens surface. Follow the instructions provided in the cleaning solution labelling. Put that lens into the correct chamber of the lens storage case. Then repeat the proceedure for the second lens.

After cleaning, disinfect lenses using the system recommended by the eye care practitioner. Follow the instructons provided in the disinfection solution labelling.

To store lenses, disinfect and leave them on the closed case until ready to wear.

To Wear your Rose K Lenses:

After removing the lenses from the lens case, empty and rinse the lens storage case with the solution recommended by your eye care practitioner, then allow the lens case to air dry. When the case is used again, refill it with fresh storage solution. Replace the lens case at regular intervals as recommended by the case manufacturer or your eye care practitioner. Always use fresh storage solution. Never reuse the storage solution in the case from the previous storage.

Always keep your lenses completely immersed in a recommended disinfecting/conditioning solution when the lenses are not being worn. If you discontinue wearing your lenses, but plan to begin wearing them after a few weeks, ask your eye care practitioner for a recommendation on how to store your lenses and how to prepare them again before wearing.

When the case is used again, always fill it with fresh storage solution.

Eye care practitioners may recommend a lubricating/re-wetting solution which can be used directly into the eye, to wet (lubricate) the lenses while they are being worn and to make them more comfortable.

Rose K lenses cannot be heat (thermally) disinfected.

Lens Deposits and the Use of Enzymatic Cleaning Proceedure:

Keratoconus patients are particularly susceptible to protein buildup on the lens surface. Once a week Rose K lenses should be cleaned with an enzymatic cleaner. Your eye care practitioner will recommend the best enzymatic cleaner. Follow the instructions provided in the enzymatic claener labelling. Some conditioning (storage) solutions may automatically include an enzymatic cleaner.

Lens Case Cleaning and Maintenance:

Contact lens cases can be a source of bacteria growth. Lens cases should be emptied, cleaned and rinsed with solutions recommended by the eye care practitioner and allowed to air dry. Lens cases should be replaced at regular intervals as recommended by your eye care practitioner or at least every 6 months. Many manufacturers now include a new lens case with every new bottle of soaking/sterilizing solution.

Care for Lens Adherence:

On occasion, during the wear of gas permeable lenses, the lens may temporarily stick to the eye. If this occurs, with the lenses on the eye, instill two to three drops of the recommended re-wetting or lubricating solution and gently rub the closed eyelids. Wait until the lens moves freely on the eye before removing it. Adherence/binding of the lens to the eye is not normal and if this occurs you should immediately consult with your eye care practitioner.

If your Rose K lens ever becomes bound/stuck to the bottom of your lens case, do not attempt to remove it using force or you may break the lens. Simply, with the lid off the case, run the case under warm water making sure the plug is in the sink. Eventually the lens will release from the bottom of the case. Always re-sterilise your lens before re-insertion.

Recommended Solutions:

We recommend the Boston range of solutions as being suitable for Rose K lenses.

Our Lens Types

"The rationalisation that you have achieved with your design is quite remarkable and I am totally converted to using your lens as my first choice"

Neil Cox - Moorfields Eye Hospital, United Kingdom

Rose K Lens

Heralded as "a quantum leap forward in the evolution of lens design for the condition" of keratoconus the Rose K lens has become the world's most frequently prescribed gas permeable contact lens for keratoconus.

Unlike traditional contact lenses, the complex geometry built into every Rose K contact lens closely mimics the cone like shape of the cornea, for every stage of the condition.

The result, a more comfortable fitting lens for patients and better sight (visual acuity).

The Rose K lenses complex geometry has only become possible since computer controlled contact lens lathes were developed to cut sophisticated oxygen permeable polymers to the right shape.

The Rose K lens has a number of features that make it ideal for keratoconus:

1. It's complex geometry can be customized to suit each eye and can correct all of the myopia and astigmatism associated with Keratoconus
2. They are easy to insert, remove and clean
3. They provide excellent health to the eye, because they allow the cornea to "breathe" oxygen directly through the lens
4. Practitioners have the Rose K trial set fitting system which achieves a first fit success in over 80% of patients internationally.


"A quantum leap forward in the evolution of lens design for the condition"

Dr. Patrick Caroline - Director of Contacts Lens Research at the Oregon Health Services University, Portland, USA

Figure 1

Standard lens designs with fixed optical zones (OZ) do not ideally fit the cone shape of keratoconus patient's. Figure 1 shows a standard lens that will yield unwanted pooling at the base of the cone and peripheral bearing that can seal off and cause corneal problems.

Figure 2


Figure 2 demonstrates the benefits of a smaller optical zone to fit the cone contour. The design results in little tear pooling at the base of the cone and shows an even distribution of tears under the lens.

The Rose K system has set optical zones to maximize vision while maintaining good corneal health.


Rose K2 Lens

Mr Paul Rose further refined the Rose K lens to take into account the unusual corneal shape of keratoconus patient's, which require abnormal curves on the back of the lens to fit the cornea optimally. This new lens is known as the Rose K2 lens.

With normal corneas the shape does not change dramatically from the centre out, but tends to change evenly in predictable amounts, and therefore with normal corneas the back surface of the lens can be designed with small incremental changes (e.g. eccentricity) over most of the lens with a peripheral curve at the edge, and usually this will achieve reasonable alignment with the cornea and a good fit.

However with keratoconus patients to achieve optimum alignment with the cornea, many curves are required on the back surface of the lens and often adjacent curves are very different. In steeper cones particularly, several curves are often required within the patient's pupil zone to achieve a good fit over the central area of the lens. Unfortunately each one of these curves gives rise to a slightly different focal point at the back of the eye. This causes the patient to experience ghosting around the object that they are viewing (like a TV with a poor reception) and this is worse the bigger the pupil is because more curves on the back surface of the lens come within the patient's pupil zone. Therefore night driving where the pupil is larger is very difficult for keratoconus patients. These multiple focuses are called aberrations.

The Rose K2 lens minimizes these aberrations by applying very small changes to the curves on both the front and back of the lens in an attempt to bring the light passing through the lens within the pupil zone to a single point.

Following extensive trials the best combination of aberration curves have been developed for computerized digital lathes to cut these very complex curves for the Rose K2 lens to give the best focus.

The new Rose K2 lens is being progressively introduced by Rose K manufacturers and distributors internationally.


Rose K Post Graft Lens

Rose K also markets the Rose K Post Graft Lens for patients who have undergone penetrating keratoplasty. This lens is designed for postoperative recovery and improvement in vision.

The new Rose K Post Graft lens is being progressively introduced by Rose K manufacturers and distributors internationally.



ACT (Asymmetric Corneal Technology)

ACT is quadrant specific and allows the steepening of the inferior quadrant onlyBy nature, the keratoconic cornea is asymmetric, where the inferior quandrant is frequently significantly steeper than the superior portion, causing the GP lens to lift off at 6 o'clock (see illustration E).

Rose K lenses incorporating ACT are designed to accomodate this asymmetry (good edgel lift at 3,9 and 12 o'clock but lift at 6 o'clock). The inferior quandrant of the lens is steeper than the superior quadrants, providing a more accurate fit at 6 o'clock making the lens more comfortable and stable (see illustration F) and often provising superior vision. ACT is independant of the primary base curve and edge lift value and is available for Rose K2, Rose K, Rose K2 IC and Rose K2 Post Graft lens designs.









Illustration E



A sperical Rose K lens (symmetric) fitted on this asymmetric keratoconic cornea fits well at 3,9 and 12 o'clock but causes the lower edge to lift off at 6 o'clock.



AVAILABILITY




Illustration F

Incorporating ACT into the design signifiacntly improves the fit at 6 o'clock, making the lens more comfortable and stable and providing superior vision.





ACT Grade #1 (0.7mm)

Slight edge stand off with pooling at or around 6 o'clock (between 5 & 7 o'clock). Specify ACT grade #1




ACT Grade #2 (1.0mm)

Moderate edge stand off with pooling and possible bubble at or around 6 o'clock (between 4 & 8 o'clock) the tear meniscus may also start to break up on blinking. Specify ACT grade #2


ACT Grade #3 (1.3mm)

Severe edge stand off or lift off (tear meniscus breaks up) at or around 6 o'clock. Specify ACT grade #3.

Note: Other grades of ACT are available (0.4mm to 1.5mm), please consult your Rose K distributor.

Rose K Irregular Cornea Contact Lens

June 15, 2007
Case Presentation
Rose K Irregular Cornea Contact Lens

History:

Patient is a 37 year old male accountant with keratoconus OD and clear PKP operated 1990 OS with a history of seasonal allergies for which he uses Patanol bid. He uses Boston soaking solution, Refresh Plus prn and Duratears ointment at bedtime. He experiences frequent discomfort and is photophobic with a foreign body sensation. Patient explains the 10.1 diameter old lens was more comfortable and wears it occasionally.

His lens is a Rose K post graft 2-- specs: 7.3 BC/10.40dia/-8.50D OS

VA @ 20ft OD sc 20/100 OS ccCL 20/25

VA N@16” OD 20/60 OS 20/25

K reading: OS 49.50 X 43.50 @90 1+ distortion

MR: OS -4.75 -4.00 X 90 20/30+ distance and near

SLE: OS lag >1mm, rocks and rides superior



2+ inferior edge lift

2+ central pooling with superior and inferior bearing with corresponding 2+ CL induced

epithelial staining of the graft.

Plan:

Refit Patient with Rose K Irregular Cornea Lens—specs: BC 7.0/11.4dia/-8.75D/ grey #1/ Optima Extra (Dk=100, WA=4)/standard edge

At one month after dispensing, patient is wearing 12-18 hours per day comfortably.

VA OS ccCL 20/20 N 20/20
Lag <1,

rides ½ mm high with minimal edge lift

1+ central pooling

secondary alignment

trace superior stain

Patient was advised to use Patanol OU bid daily for 3 months during allergy season and to clean only with Boston cleaner at day’s end and soak in Boston wetting for insertion the next day; Refresh Plus and Duratears ointment discontinued; he should use only Boston rewetting or Blink(AMO) prn for episodes of dryness to preserve the wetting angle.

Analysis:

Patient is now happy and satisfied for first time since PKP in 1990.

Wavefront analysis with and with out Rose K IC:

RMS is 1.440 in the OPD and total aberrations are 10.922 without lens;

with the lens, there is virtually no overrefraction, VA is improved to 20/20, RMS is 0.27 and total aberrations are reduced to 1.290.

Magrabi OS

Conclusion:

The Rose K IC lens is effective in fitting irregular corneas that do not respond to smaller diameter fitting; I have used the Rose K IC lens for post graft, post refractive surgery keratoectasia (reverse geometry lenses are not readily available), pellucid marginal degeneration and large, inferior global keratoconus. The proper use of the Boston cleaning solution at the end of the wearing schedule only preserves the wetting angle and the cornea integrity is protected by using high Dk(Oxygen Permeability) and low Wetting Angle(WA). In conclusion, the Rose K IC contact lens is a welcome addition to the selection of lenses in difficult fits.

Author:



John Steile OD, FAAO

Magrabi Eye Center

Dubai

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

roseklens.com - Rose K - Contact Us
Contact Us

You can contact us at:

Menicon Co., Ltd
3-21-19 Naka-ku
Nagoya 460-0006
Japan

Tel: +81-52-937-5021
Fax: +81-52-935-1121

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

About the Inventor

Paul Rose was educated at Auckland University, New Zealand, graduating in Optometry in 1967 and again in 1969 with a BSc in Psychology and Mathematics.

He has served on the Council of the New Zealand Society of Contact Lens Practitioners for a period of ten years including a term as president.

Paul is a recognized international speaker at optical conferences having spoken on a variety of subjects including keratoconus lenses, case contamination, solution sensitivity and contact lens fitting including post graft, piggy-back lenses and aphakic lenses for babies.

He specializes in keratoconus patients and is the designer of the Rose K lens. Paul Rose and Peter Walker currently consult with keratoconus patients at Visique Rose Optometrists in Hamilton, New Zealand. [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]

In 2000, Paul was awarded the Creative Design and Process Award for his Rose K design from the Contact Lens Manufacturers Association (CLMA) of America and in 2007, he was awarded the European Federation of Contact Lens Industry (EFCLIN) Technology Award for his work in the field of contact lens design for the irregular cornea.

Keratoconus




Eliminate KC as a Health Issue
- Through Education -



Introduction


Keratoconus (kehr-uh-toh-KOH-nus) is the most common corneal dystrophy that leads to severe visual impairment, with a prevalence of 1 to 430/2000. It is not a common known eye disorder, but it's by no means rare, and it is becoming more common due to the use of modern diagnostic equipment. Corneal transplant is the most commonly performed transplant surgery. Keratoconus is the most common degenerative condition of the front (window) of the eye which leads to corneal transplantation in the Western world.

Keratoconus is a condition in which the normally round, dome-shaped cornea (front window of the eye) thins and becomes distorted and irregular. A cone-like bulge develops, resulting in significant visual distortion. The apex of the cone is usually displaced outwards and downwards and in the line of sight, creating irregular astigmatism.

Until recently, KC was managed by fitting a rigid gas-permeable contact lens, and penetrating keratoplasty when contact lenses could not be tolerated any more. With one in five needing a penetrating keratoplasty (the traditional corneal transplant), our mission was to reduce the numbers having this invasive surgery, which is now happening.
Advanced treatment modalities enable earlier intervention to improve the prognosis and visual rehabilitation, and which are now available.


Keratoconus


An eye with Keratoconus


Etiology

* The underlying reason for its development remains obscure; currently the topic of much research

* Usually an inherited corneal disorder, often in an autosomal recessive fashion

* Family members may have it, but it also can be random with no other family members affected (sporadic)

* Most likely that the cause is due to more than one factor

The path that leads to the thinning of the cornea may start with a "trigger", followed by a cascade of events in the eye tissues

The primary trigger is not known

Possible options include hormonal changes in the patient, genetic predisposition to altered cytokines and/or their receptors in the patient's cornea, or a pattern of eye-rubbing or poor fitting RGP lenses that could release factors

Abnormal levels of degradative protease activity may then lead to a slow, progressive dissolution of Bowman's layer and the epithelial basement membrane

The epithelium then comes into contact with the stroma, cytokines/growth factors are released, and as a result, the cells begin to produce scar tissue and proteases

* A disorder with local micro-environmental changes rather than a situation where the entire cornea is involved

Within a single keratoconus cornea there are areas of increased protease activity (thinning) and other areas of ongoing wound healing (scar tissue buildup)

* Recent advances in molecular techniques make it possible to examine the molecular components in wounded or diseased corneas

CD45 (leukocyte common antigen or T200), a transmembrane phosphotyrosine phosphatase (normally found associated with blood cells), has been found to be present in more cells within keratoconus corneas than normal

These cells may represent the source of some of the proteolytic enzymes reported to be associated with keratoconus

A gene product referred to as glucose regulated protein (GRP78) has been found in greater quantity in normal corneas

A protein that aids or "chaperones" the folding and secretion of other proteins produced in cells.The reduction in GRP78 could affect the secretion and folding of the major structural proteins of the cornea which are reduced in the keratoconus cornea.

The cause of Keratoconus is not fully known



Keratoconus
The map above shows the distribution of the general population world-wide





Incidence and Carrier Frequency

* Some cases have a hereditary component and studies indicate that about 10% of patients have affected relatives
* Most cases appear to be sporadic

* The actual incidence is uncertain, large studies estimate 50 to 230 per 100,000
* According to one study, the estimated prevalence in first-degree relatives is 3.34%, which is 15 to 67 times higher than that in the general population (0.23-0.05%). (Am J Med Genet 2000 Aug 28;93(5):403-9 )
* Occurs in all ethnic groups, with certain ethnic groups effected more

* Has a slight female preponderance

* Is more common in contact lens wearers and nearsighted eyes

* Some researchers believe allergy may play a role


Keratoconus


Shown above is the contour of a normal cornea






Keratoconus

Shown above is the contour of a Keratoconus cornea




Clinical Features


* Non-inflammatory eye condition in which the normally round dome-shaped cornea progressively thins causing a cone-like bulge to develop

Results in significant visual impairment

* A degenerative condition where the cornea thins in affected areas and scar tissue develops

Can lead to astigmatism - often regular at first but becoming increasingly irregular as the disease progresses

* Surface thinning can create several optical zones that individually focus the same image to different areas of the retina, thus creating multiple perceived images

* Has been associated with other medical disorders including atopic disease, Down's syndrome, Ehlers-Danlos syndrome, Marfan's syndrome, craniofacial dysostosis and osteogenesis imperfecta

* Not a blinding disorder in the classical sense, but does result in increasing near-sightedness (things are out of focus at a varying distance) and irregular astigmatism (things look distorted)

* Is almost always bilateral (90% of cases)




Natural History

* In the earliest stages, slight blurring, distortion of vision, and increased sensitivity to glare and light occur

Symptoms usually first appear in the late teens and early twenties

Mean age of onset is 16; onset as young as 6 yrs has been recorded

Rarely develops after age 40

* May progress for 10-20 years and then slow in its progression

May halt at any stage from mild to severe

* Each eye may be affected differently

Disease develops asymmetrically: diagnosis of the disease in the second eye generally occurs about five years after diagnosis in the first

* Patients may endure discomfort and reduced vision over a long period of time.




Keratoconus

Testing



* Can usually be diagnosed with slit lamp examination of the cornea

* Early cases may require corneal topography, a test that makes a stereo image which gives a topographic map of the corneal curvature

* When advanced, the cornea will be thinner in areas and this can be measured by pachymetry

* The biomicroscope is the only tool which allows a clinician to observe many classical signs of keratoconus: Fleischer's ring, stress lines of Vogt, corneal thinning and scarring, various types of staining with and without lens wear, increased visibility of corneal nerves, and corneal hydrops


Keratoconus



Ghosting
Keratoconus


Glare

Keratoconus

Normal Vision




Symptoms

As Keratoconus progress’s the abnormalities of the cornea severely affect the way we see the world, making simple tasks like driving, watching TV or reading a book, difficult. This distortion has been compared to viewing a street sign through your car windshield during a driving rainstorm.

* Decreased visual acuity due to irregular astigmatism and/or corneal scarring (frequently changing prescriptions with glasses or contact lenses)
* Distorted and blurred vision (depening on light levels, changing/fluctuating vision can also occur)
* Glare and light sensitivity
* An acute corneal hydrops may induce pain



Keratoconus


Signs

* Bilateral, progressive thinning of the corneal stroma, most often paracentral temporal inferior
* Distortion of the corneal contour with keratometry and computerized corneal topography, retinoscopy, and keratoscopy
* Vertical Vogt's striae may be evident in Descemet membrane at the apex of the cone
* Munson's sign: indentation of the lower lid by the conic cornea in downgaze
* Fleischer's ring: ring shaped iron deposition at the level of the epithelial basement membrane
* Descemet membrane rupture may result in acute hydrops with stromal edema and subepithelial central scarring

Corneal curvature
Mild keratoconus < 45D
Moderate keratoconus 45 - 52D
Advanced keratoconus 52 - 65D
Severe keratoconus > 62D


Corneal thickness in microns
Normal cornea 543 Microns
Early keratoconus 506 Microns
Moderate keratoconus 473 Microns
Advanced keratoconus 446 Microns


Keratoconus




Management
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Glasses can be prescribed to correct the induced astigmatism in early keratoconus. Once the cylindrical power increases beyond 4.0 diopters visual intolerance may occur at which time prescribed contact lenses are needed
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UV - Crosslinking to treat the progression of KC as early as possible, which in differential use (please ask your ophthalmologist) can be accompanied in accordance to the remit of various other vision correction methods (as seen below)
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Fitting of high performance soft lenses, soft-perm, piggyback lens systems, and rigid gas-permeable Prescribed Contact Lenses
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Scleral Lens Prosthetic Device


Correct fitting and continued aftercare is essential with all medically necessary Contact Lenses.

Selective cases (and by selecting your surgeon carefully) may be suitable for the following surgical operations :

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Intacs
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Ferrara Rings
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Implantable Contact Lenses (Phakic / Toric)
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Deep anterior lamellar keratoplasty (DALK)

At selected locations, selective cases may be eligible for (made possible due to UV - Crosslinking) limited customized topography guided surface ablation, microscopic surgery, epikeratoplasty or an ALTK. A Penetrating Keratoplasty is considered as an absolute last option.

Prognosis
With advanced treatment modalities, complete visual rehabilitation may be achieved with an excellent long-term prognosis