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What does differential diagnosis mean in relation to Keratoconus? Could I ask a Keratoconus specialist?

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My son is the patient not me. What does differential diagnosis mean in relation to Keratoconus or in general for that matter and do you know all the currently available treatments world-wide for Keratoconus? Should this go to a Keratoconus specialist? There is so many different technologies nowadays. It is difficult keeping up.
Posted Sat, 31 Aug 2013 in Vision and Eye Disorders
Answered by Dr. Mihir Shah 53 minutes later

Thanks for the query.

The word keratoconus is derived from latin words, kerato- "cornea" and -conus meaning "cone shaped". This describes the normally round shaped cornea becoming cone-shaped with the progression of the condition. The keratoconic cornea also tends to thin with progression of the condition. Generally keratoconus is a painless condition although it can cause some ocular irritation in more advanced cases.
The severity of keratoconus varies widely between individuals, some may manage with spectacles alone, others may require special contact lenses and a small minority go on to require surgery. Although keratoconus is considered a progressive condition (one that worsens over time) it is common for keratoconus to eventually stabilise (often around the age of 30).
Keratoconus is considered to be a genetic condition, and it is common to find more than one family member (or relative) with the condition.
Conditions such as allergy (hayfever), eczema and asthma are common in people with keratoconus.

In general, spectacles do not provide the best level of vision compared to specialised contact lenses as they do not completely neutralise the corneal distortion. However, in early keratoconus spectacles may be a reasonable option. In more more advanced keratoconus spectacles tend to be reserved as a back-up option.

Contact Lenses
Contact lenses are generally considered to be the main-stay of keratoconus management. The main types are soft and RGP (rigid gas permeable) lenses. There are many variations of both soft and RGP lenses, some more suitable for early keratoconus and others for advanced keratoconus.
Due to the complicated nature of the keratoconic eye, it pays to check your optometrist is experienced in fitting contact lenses for keratoconus.
The initial fitting and follow-up process usually takes a number of visits

Surgical Options
Also known as "corneal grafting" this procedure involves replacing your own irregular cornea with a donor cornea. There are several variations, most commonly penetrating keratoplasty (PK) and deep lamellar keratoplasty (DLK).
PK involves removing a full-thickness "button" of cornea about 8mm in diameter. The donor cornea is then sewn into place.
With DLK, the thin back layer of the cornea (called the endothelium) is left in place (so the incision does not quite go through all the layers) and the donor cornea is sewn into place on top of this.
As the donor cornea in foreign to the body, it is possible that the eye may try to reject the donor cornea. While this can usually be managed with medications (typically corticosteriod eye drops), is is probably the most significant reason for graft to "fail".
As DLK leaves the original endothelium intact, there is significantly less chance of rejection when compared to PK. However the visual outcomes (clarity) of PK tend to be better. Generally, which method of keratoplasty is performed is a decision made in conjunction with the ophthalmologist (eye surgeon).
One main reason for considering keratoplasty includes failure to able to maintain a lens on the eye. This is normally due to the keratoconus being so advanced that physically keeping a lens on the eye becomes impossible or risks damage to the eye. The other common reason for surgery is due to corneal scar tissue caused by the keratoconus reducing the vision significantly. Essentially, the cornea "stretchs" and develops scar tissue over the apex (peak) of the cornea. This creates a clouding of vision that contact lenses may not be able to correct effectively.
Keratoplasty is generally considered to be a last resort of patients with keratoconus. It is (almost) certain the a patient will still require either spectacles or contact lenses to correct the vision following keratoplasty.

Collagen Cross Linking (CCL)
CCL is a recently developed procedure designed to halt the progression of keratoconus. This is achieved by increasing the rigidity (stiffness) of the cornea preventing it from continuing to distort. The procedure involves removing the thin surface layers of the cornea (epithelium), saturating the cornea with riboflavin (vitamin B2) XXXXXXX then treating the area with UV light. The UV reacts with the riboflavin to increase the bonding between the collagen fibres that make up the cornea. The effect is a greatly increased rigidity and resistance to progression of the keratoconus. It does not cure the keratoconus but prevents it getting worse. Collagen cross linking is an exciting procedure that should reduce the numbers of patients requiring keratoplasty (corneal grafting).
CCL is best performed before the keratoconus gets too advanced, therefore it is recommended all keratoconic patients with children have them tested for keratoconus (with corneal topography) from the age of 8. This will ensure that if keratoconus develops it is diagnosed early.

These are small semi-circular plastic rings that are implanted into the cornea. The idea is to "stretch" the central cornea, causing it to flatten and reduce the visual distortion. The results tend to be variable and although they may improve the vision to some degree in mild cases, they do not usually eliminate the the need for contact lenses. They are seldom of benefit in more advanced cases of keratoconus. However, they can be removed should the need arise.

You need to consult a cornea specialist who will guide you as to which of the options is best suitable for your son.

Best regards,
Dr.Mihir Shah

Above answer was peer-reviewed by
Follow-up: What does differential diagnosis mean in relation to Keratoconus? Could I ask a Keratoconus specialist? 21 hours later
Thank you Dr Shah,

I appreciate what you have given me. Obviously, in advanced cases, there is not much option except the DLK which, I would imagine, would heal faster than the PK. However, through my own research on the web, I knew about these treatments. Certainly, the opthamologist (mentioned below) did not bother to inform my son. I think he performs a Keratoconic operation that took him two years to learn in Canada. When I asked my question, I did say that I would like to know about treatments for Keratoconus world-wide. I was hoping your company may have known other treatments that I do not.
For your information and therefore other keratoconus sufferers, there is another treatment used in Europe, XXXXXXX England and New Zealand (NZ) to name a few countries. It is called Keraflex and the procedure can be used with the now famous CCL. (NZ) has only 3 million persons and has 2 machines that Avedro (the makers of medical machines) designed for this procedure. The Australian opthalmologist who practises in both Ipswich and Brisbane, in Queensland, Australia became very nasty when my son asked for his own results to go to one of the two opthalmologists in (NZ) who has the Avedro Keraflex machine. However, after much persistance, he had no choice but to send what we hope were not fake results but Simon's real results to (NZ). Unfortunately, the (NZ) doctor replied via email that Simon's eyes were not appropriate for the Kerflex procedure. I am sure that Australia does not have the machine because of opthalmic politicking. Multinational companies can be ruthless with each other. I can guess a few reasons why some opthalmic doctors in Australia have kept it out. The persons who are lucky enough to have the Keraflex with CCL?CXL will never have to have a transplant if these patients are diagnosed early enough. I hope this extra information to you helps other sufferers of Kerataconus even though my son is beyond it.
Answered by Dr. Mihir Shah 12 hours later

Keraflex is done at XXXXXXX Nethralaya, Bangalore, India. The results are similar to collagen crosslinking. However crosslinking can be done for most of keratoconus patients. keraflex can be done only for early cases. We will have to wait for a year to get a worldwide consensus on this procedure. Anyways thank you for your interest and concern.

Dr.Mihir Shah
Above answer was peer-reviewed by
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