What is myopia?
Myopia (near-sightedness) is one of the most common refractive errors worldwide. It is a vision condition in which people are able to see close objects clearly, but objects farther away appear blurred. People with myopia can typically see well enough to read a book or computer screen but struggle to see objects farther away. Sometimes people with undiagnosed myopia have headaches and eyestrain from struggling to focus objects in the distance.
What are the Causes of Myopia?
Myopia occurs when the eye grows too long from front to back. The lens of the eye focuses the image in front of the retina (the light receptive layer at the back of the eye) instead of on the retina. Myopia also can be the result of a cornea (the eye’s outermost layer) that is too curved for the length of the eyeball or a lens that is too thick. Although the tendency to develop myopia may be inherited, its actual development may be affected by how an individual uses his or her eyes. People who spend considerable time reading, working at a computer, or doing other intense close-up visual work may be more likely to develop myopia.
How is Myopia Diagnosed?
Your ophthalmologist may use several procedures to measure how the eyes focus light and to determine the power of any optical lenses needed to correct the reduced vision.
As part of the testing, your ophthalmologist will perform:
Comprehensive Eye Examination
A comprehensive eye examination including a dilated fundus examination to rule out any structural problem of your eyes.
Visual Acuity Test
A visual acuity test requires the patient to identify letters on a distance chart. This is written as a fraction, such as 6/12 or 20/40. Normal distance visual acuity is 6/6 or 20/20, although some people may have “better” vision (6/5 or 20/15).
What is High Myopia?
High myopia significantly increases the risk of retinal detachment as the retina is thinner and weaker than normal. Also, high myopia can increase the risk of cataract and glaucoma. Each of these conditions can cause vision loss. Normally, an eye is considered to have high myopia if it requires - 6.0 diopters or more of lens correction
What is Pathological Myopia?
Pathological myopia sometimes occurs in eyes with high myopia, when the excessive elongation of the eye causes changes in the retina, choroid, vitreous (gel-like substance that fills the centre of the eye), sclera (outer white coating of the eye), and/or the optic nerve. Symptoms of pathological myopia typically first appear in childhood and usually worsen during adolescence and adulthood.
Treatment cannot slow or stop elongation of the eye; however, complications such as:
- Retinal detachment,
- Macular oedema (build-up of fluid in the central part of the retina),
- Choroidal neovascularization (abnormal blood vessel growth), and
Can usually be treated.
What are the treatments for Myopia?
Conventionally, myopia can usually be corrected with prescription glasses or contact lenses.
Other treatment options for Myopia include:
- Refractive surgery
- Phakic intraocular lens implant
Refractive Laser procedures have been used to treat myopia in adults include:
- LASIK (laser in situ keratomileusis)
- PRK (photorefractive keratectomy)
- SMILE (small incision lenticule extraction)
The amount of myopia that PRK or LASIK can correct is limited by the amount of corneal tissue that can be safely removed.
PRK (Photorefractive Keratectomy)
In the PRK procedure the surface layer of the cornea is removed before a laser beam of light reshapes the cornea in order to refocus light entering the eye.
LASIK (Laser in situ keratomileusis)
In the LASIK procedure only the tissue from the inner layers are removed, but not from the surface, of the cornea. In order to do this:
- A section of the outer corneal surface (flap) is lifted
- The flap is folded back to expose the inner tissue
- A laser then removes the precise amount of corneal tissue needed to reshape the eye
- Then, the flap is placed back in position to heal
Small incision lenticule extraction (SMILE)
Small incision lenticule extraction (SMILE) is the latest laser refractive procedure in which:
- A special laser is used to create a small disc inside the intact cornea
- The ophthalmologist will then extract the disc out of the cornea through a keyhole incision
The benefits of this procedure are:
- Minimal discomfort
- Quicker recovery time
- Reduction of the incidence of dry eye syndrome following surgery
Additional Artificial Lens Implant for Myopia
People who have high myopia or whose corneas are too thin for laser procedures may be able to have their myopia surgically corrected. A small artificial lens implant with the desired optical correction may be inserted in their eyes. The implant can be placed just in front of the natural lens (Phakic intraocular lens implant).
Which surgical approach is the best surgery for Myopia?
Your ophthalmologist will advise you after reviewing your condition and needs.