What is done in a cross-linking operation? Is this operation really effective?

The cornea is made of a network of collagen fibers. In this disease interlinking connections between the collagen fibers become week due to which the corneal thickness decreases and the cornea is weakened.

In this treatment, the collagen fibers are activated and their linkages between each other are potentiated and their cross-links are fastened together with each other. A chemical named riboflavin is activated with a special type of ultraviolet radiation, as a results the fibers of the collagen come closer to each other again, and thickness of cornea increases. This process is called cross-linking. This operation is also called CXR or CR3 operation.

As this chemical and radiation machine are still expensive so the operation is much expensive and is being performed at very few places.

The pictures below show the different stages of this operation

What is appearance of cornea when it is damaged? What are symptoms other than its abnormal appearance?

If there is a minor defect, the color of your eye may appear slightly greyish. If cornea has been significantly damaged, then the eye appears white in colour. Vision deterioration is proportional to the whiteness. If inflammation is also present, then, there is pain, redness, photophobia. Bright light is intolerable. But in the case of old healed lesion, usually only vision deterioration and the white appearance is present.

How the cornea of other’s eye you fix to another’s eye? How do you perform keratoplasty?

This is very important surgery in which we transplant another person’s eye to the patient. Look at following pictures it will help you in understanding the surgery.

What is appearance of cornea when it is damaged? What are symptoms other than its abnormal appearance?

If there is a minor defect, the color of your eye may appear slightly greyish. If cornea has been significantly damaged, then the eye appears white in colour. Vision deterioration is proportional to the whiteness. If inflammation is also present, then, there is pain, redness, photophobia. Bright light is intolerable. But in the case of old healed lesion, usually only vision deterioration and the white appearance is present

?Is keratoconus curable

This depends upon the stage of disease at the time of initiating the treatment. Spectacles, hard contact lenses, and intacs all can be helpful at early stages of the disease. When the cornea becomes too thin or non-transparent, then only corneal transplantation is beneficial. However, the latest method for treating it is CXR or C3R. With this technique, it has become quite possible to treat the cause of the disease.

?What is done in cross-linking operation? It is how much effective

Cornea is made up of collagen. This is a protein found in form of fibers. The fibers form a network which acts as infrastructure of the cornea. In the patients with keratoconus, the cross-links between these fibers of the network become week. When the cross-links weeken, the threads separate and in-between distance increase. This the mesh weakens and the cornea becomes thinner. The corneal globe enlarges.

In this method of corneal cross-linking, the collagen fibers are activated with a dye named Riboflavin. Then the activated fibers are treated with a special type of ultra-violet ray. This results into strengthening of the cross-links. As a result the fibers come closer to each other again and the thickness of the cornea increases again.

Since this drug and UV emitting device are both expensive at this time, so the treatment is yet expensive.

?What are other methods to treat the patients with keratoconus

This depends on the stage of the disease at the time of initiation of treatment. The patients are periodically carefully monitored and different treatments are given and advanced according to the progress of the disease. Following methods are used.

Glasses

Initially, the glasses are advised.

Contact lenses

When there less improvement in vision with glasses, then hard contact lenses can be very helpful.

Intact

At advanced stage, there is high irregular astigmatism. At this stage spectacles and contact leses do not gave much benefit. Intacts may be advised at this stage.

The cornea of some has a weakness. A part of cornea starts thinning and then it starts bulging at a site slightly lower to the center of the cornea. As a result the central part of the cornea appears as a cone. From here the name keratoconus has been derived. The thinning of the cornea sometimes is so severe that in the center the layers rupture. Fluid rushes into the cornea. It becomes thick and hazy. This situation is called acute hydrops. In the following pitures gradual changes in the cornea has been shown:

What is the basic defect in the cornea?

There are different reasons in different patients. But mostly it is very difficult to identify in a specific patient. Intensive research is going on to identify the exact etiology and its pathogenesis. There are evidences that this has hereditary basis, also conditions causing chronic irritation and itching also can give rise to this condition. Some patients develop after LASIK operation.

One common thing in all patients is that the cornea is made up of a network of fibers. They are closely and regularly arranged in a very fantastic manner. In this disease theye separate apart. This increased distance between the fibers of the network results into thinning of the cornea.

What are the symptoms of keratoconus?

Vision is continuously deteriorating. Gradual weakness of vision and change in number of glasses. Even no improvement with any number of glasses. Mostly there is significant increase in cylindrical number. In advanced cases patient may feel even pain, watering, redness especially when proceeding towards development of acute hydrops.

There are many other signs which can be found by doctors by examining on microscope. Also special diagnostic instruments are required for its diagnosis. Specially important is corneal topography. In the following pictures the corneal topography machine has been shown:

Is there any special test for it?

Special significance is given to corneal topography. This test evaluates changes in the levels of the surface. The highest part of the cornea appears red. In the following pictures some results has been shown:

 

بعض لوگوں کے قرنیہ میں یہ کمزوری ہوتی ہے کہ درمیان میں سے پتلا ہونا شروع ہو جاتا ہے، جس سے قرنیہ کا مرکزی حصہ آہستہ آہستہ آگے کو اُبھرنے لگتا ہے اور قرنیہ کی شکل مخروطی ہوتی چلی جاتی ہے۔ قرنیہ کا مرکزی حصہ کئی لوگوں میں اس حد تک پتلا ہو جاتا ہے کہ بالآخر پھٹ جاتا ہے اور قرنیہ کے درمیان میں سوراخ ہو جاتا ہے۔ اِن تصاویر میں قرنیہ کی بتدریج بڑھتی ہوئی خرابی کے مختلف مراحل دکھائے گئے ہیں:

قرنیہ کے اندر یہ خرابی کیوں پیدا ہوتی ہے؟

مریضوں کی اکثریت میں یہ تعین کر نا ممکن نہیں ہوتا۔ اب تک کی تحقیقا ت سے یہی اشا رے ملتے ہیں کہ ورا ثتی نقشے میں اِسی طرح کا قر نیہ بنا نے کے احکا مات ہو تے ہیں۔ کئی لوگوں میں لاسک اپر یشن کے بعد بطور پیچیدگی کے یہ کیفیت سا منے آتی ہے؛ قر نیہ کے اندر اگر بڑا زخم بن جا ئے اور لمبے عرصہ تک اُس میں سوزش چلتی رہے یا کسی اور وجہ سے قر نیہ مسلسل متو رّ م رہے تو اِ س سے بھی اس کیفیت کے سا منے آ نے کے امکانات ہو تے ہیں۔

قر نیہ پروٹین کی ایک قسم کولیجن Collagen ہے۔ یہ دھاگوں کی شکل میں پائی جاتی ہے۔ ان دھا گوں کا جال بنا ہوا ہوتا ہے۔ قرنیہ مخروطیہ کی بیماری میں مبتلا مریضوں کے قرنیہ کے ان دھاگوں کے آپس میں جُڑنے میں کمزوری آ جاتی ہے۔ جب دھاگوں کا آپس کا تعلق کمزور ہو جاتا ہے تو اس سے جال کے سُوراخ  بڑے ہو نا شروع ہو جا تے ہیں اور قر نیہ پتلا ہو نا شروع ہو جا تا ہے۔

اِس کی علامتیں کیا ہیں؟

نظر مسلسل کمزور ہونا شروع ہو جاتی ہے اور تھوڑے ہی عرصے میں یہ حالت ہو جاتی ہے کہ کسی بھی عینک سے نظر پوری ظرح صاف نہیں ہو پاتی ۔ عینک کے نمبر کا بڑا حصہ سلنڈر کی قسم کا ہوتا ہے۔ جب بیماری کافی آگے بڑھ چُکی ہو تو آنکھ میں درد محوس ہونا شروع ہو جاتی ہے، پانی آنے لگتا ہے، اور آنکھ سرخ رہنا شروع ہو جاتی ہے۔ اِ س کے علاوہ بھی بعض ایسی علامات ہوتی ہیں جو ڈاکٹر صاحبان کو ہی نظر آ سکتی ہیں ۔ اِس کے لئے ٹوپوگرافی ٹسٹ بہت مدد گار ہوتا ہے جس میں ایک بہت جدید مشین سے قرنیہ کی سطح کی تصویریں لی جاتی ہیں اور اُس کے مختلف حصوں کی اونچا ئی کا باہمی موازنہ کیا جاتا ہے۔ جیسا کہ درج ذیل کی تصاویر میں نظر آ رہا ہے:

کیا تشخیص کے لئے کوئی ٹسٹ بھی کیا جاتا ہے؟

اِ س کی بعض ایسی علامات ہوتی ہیں جو ڈاکٹر صاحبان کو ہی نظر آ سکتی ہیں ۔ اِس کے لئے ٹوپو گرافی Corneal Topography  ٹسٹ بہت مددگار ہوتا ہے جس میں ایک بہت جدید مشین سے قرنیہ کی سطح کی تصویریں لی جاتی ہیں اور اُس کے مختلف حصوں کی اونچائی کا باہمی موازنہ کیا جاتا ہے۔ جیسا کہ درج ذیل کی تصاویر میں نظر آ رہا ہے: