Latest Advances in Surgeries for Vision Correction

Dr. John CHANG

Director, Refractive Surgery

Honorary Consultant in Ophthalmology

Specialist in Ophthalmology   

Prof. Guy Hugh CHAN, a world-renowned authority on ophthalmology, was invited to join HKSH and set up Hong Kong’s first refractive surgery centre in 1996. Now one of the leading LASIK providers in Hong Kong, the HKSH Guy Hugh Chan Refractive Surgery Centre has performed laser refractive surgery on more than 120,000 eyes in over 20 years. It is also the first accredited local LASIK training centre.

Thanks to the advances in surgical technique and equipment, patients can now opt for LASIK or SMILE according to their needs after detailed examination and discussion with our eye specialists.  

Types of Refractive Errors:

1. Myopia
   
   
   A near-sighted eye is longer than normal, so light rays focus in front of the retina. Close objects can be seen more clearly while distant objects look blurred.

2. Hyperopia
   
   
   A far-sighted eye is shorter than normal, so light rays focus behind the retina. Distant objects can be seen better while close objects look blurred. However, the lens in the eye can thicken and increase the light bending power plus making the image clear again.

3. Astigmatism
   
   
   Many people with myopia or hyperopia have some degree of astigmatism. This is caused by asymmetric curvature of the cornea or lens. Astigmatism distorts the light rays entering the eye and focus unevenly on the retina. Objects look distorted and blurred.

4. Presbyopia
   
   
   In a normal eye, light rays of close objects focus behind the retina, which is similar to a far-sighted eye looking at distant objects. The lens of a normal eye can change its shape and therefore refocus light rays on the retina, so a sharp image is formed. This process is called accommodation and it is automatic. With increase in age, the lens of the eye loses its flexibility and becomes less able to change its shape to accommodate. When people reach their forties, tasks such as reading small prints become difficult.

Laser Refractive Surgery

1. LASIK

As the most common laser refractive surgery, LASIK corrects vision by creating a cornea flap with femtosecond laser and adjusting corneal curvature with excimer laser. It is suitable for people of myopia below 1,200 degree, hyperopia below 600 degree and larger pupil, and recovery is fast after surgery. It is the most common outpatient procedure in the world.

People with uneven cornea may opt for Custom LASIK to selectively remove or retain cornea surface tissue. It further improves both day and night vision, i.e. less halo and glare.

2. SMILE

In SMILE, an intrastromal lenticule is first cut using femtosecond laser. The lenticule is then removed through a 2 to 4 mm incision to change the corneal curvature. The incision made in SMILE is smaller than that of LASIK, thereby retaining the biomechanical strength of cornea with minimal damage to its nerves.

SMILE is not suitable for patients with hyperopia. 

The side effects of LASIK and SMILE are similar in nature, e.g. mild temporary dry eyes or halo at night. Patients can usually return to work the day after surgery. They can use eye make-up 1 to 2 weeks later, and swim after a month.

3. Others

Those involved in contact sports or thin cornea can undergo other laser refractive surgeries like LASEK, PRK or TransPRK with Xtra to enhance cornea strength.

Implantation of Phakic IOL

If you are deemed not suitable for any of the above procedures, you may opt for placement of phakic IOL between the lens and the cornea. It can treat myopia (max: 1,800 degrees), hyperopia (max: 1,000 degrees) and astigmatism (max: 600 degrees). The natural lens is not removed during surgery, thus the ability to automatically adjust focus is retained. You can undergo LASIK if there is adequate cornea tissue for further vision enhancement.  

Patients with phakic IOL are at low risk of cataract, and should attend follow-up consultation every year. For those with cataract, an intraocular lens can be implanted during cataract surgery to correct myopia, hyperopia, astigmatism and presbyopia in one go.