What is Photorefractive keratectomy (PRK) … and what are its advantages ?

What is Photorefractive keratectomy (PRK) … and what are its advantages ?

PRK differs from traditional LASIK in the way the corneal tissues are exposed to the EXCIMER laser. In PRK, no flaps are lifted and a no cuts are made into the corneal thickness. 

The covering layer of the cornea is carefully peeled off and the EXCIMER laser in applied directly to corneal tissue. It can be used in cases of myopia, hyperopia, astigmatism. This technology works better if the error is mild or moderate only. 

Who are candidates for this surgery? Patients with the following :

  1. Mild to moderate errors
  2. Patients with thin corneas that precludes LASIK
  3. Contact sport athletes
  4. Mild to moderate keratoconus patients who have done corneal cross linking to strengthen the corneal tissues beforehand. 

What are the advantages of this surgery?

This surgery does not require a flap to be elevated, its is also characterized by simplicity and accuracy when done by the most experienced eye doctors and best skilled eye surgeons. It suits most patients seeking refractive surgery and is a great substitute for more advanced technologies like femtolasik or FemtoSMILE in patients with low average thickness corneas . this kind of surgery corrects all errors of refraction that  affect the eyes.

What are the investigations needed before the surgery?

  • Corneal topography and thickness mapping
  •  Measuring the intraocular pressure
  • Complete retinal examination and measuring visual acuity. 

What are the types of PRK?

there are 4 main types of PRK, that have few highly technical differences between the way the surface layer of the cornea is removed 

standard PRK: the eye doctor uses a special brush to carefully peel off the epithelium of the cornea (outermost covering layer) then the EXCIMER laser is used to reshape the cornea according to the patient’s predetermined error. 

PRK with Alcohol:

A certain concentration of alcohol is placed on the epithelium to aid in removing it. this makes the epithelium peeling more uniform and prevents infections after the surgery. 

PRK using the microkeratome :

This technology uses a precise automated  surgical blade to lift off the corneal epithelium and preserving it until the EXCIMER laser reshapes the cornea. 

EXCIMER PRK:

The EXCIMER laser is used to directly evaporate the epithelium and the desired corneal layers to achieve the best visual results .

How is the surgery done?

Your eye doctor will instill numbing eye drops 

The Epithelium is then peeled off as mentioned above

The EXCIMER laser is focused on the corneal tissues to reshape it according to the surgical plan discussed with the patient

The whole procedure takes about 10 minutes for both eyes. 

Can custom EXCIMER laser be used in PRK?

Yes, it can be used for patients that require this technology, who have what is called higher and lower order aberrations to correct these in addition to the common errors of refraction . the EXCIMER laser machine is set according to the data of the wavefront images and other corneal imaging done before the surgery, therefore the pattern of laser ablation is customized to the patient’s results and no two people can be the same. This gives more superior visual results in the indicated cases , like those that suffer from haloes around light and glare, and poor night vision. 

What are the expected side effects after the surgery?

A contact lens might be placed onto the cornea after the surgery until the surface layer completely heals . 

Dry eye can occur and last for a few weeks. Patients are advised to use their eyedrops, and to avoid rubbing the eyes under any circumstance.

Prickly feeling and excessive tears lasting for about 3 days

A follow up schedule will be determined with your ophthalmologist to revise your case.  

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أستاذ طب و جراحة العيون م. طب عين شمس أستشاري جراحات تصحيح عيوب الابصار و المياه البيضاء و القرنية عضو الجمعية الامريكية لعلاج العيون و تصحيح العيون بالليزر زميل المجلس العالمي لجراحة و طب العيون زميل الكلية الملكية لطب و جراحات العيون بأنجلترا

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About the doctor

A consultant specializing in corneal, cataract and Glaucoma Surgery and Refractive surgery in Egypt, Assistant Professor of Ophthalmology – Ain Shams University, Consultant cornea, cataract, and Glaucoma Surgery and Refractive Surgery, Fellow of the Royal College of Physicians and Surgeons of Glasgow, UK.

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