Laser eye surgery glossary
S
Sclera
The tough, white, outer layer (coat) of the eyeball that, along with the cornea, protects the eyeball. Further reading
Short-sightedness
The distortion of sight because the eye is too long for its focusing power. The laser eye surgery corrects this by reducing the curvature of the cornea, which enables light to reach the retina at the back of the eye. The short-sighted eye bends light too much and focuses the image in front of the retina. To reduce this 'over bending' a negative lens distorts the light before it gets into the eye and so the light can be focused on to the retina. Further reading
Slit lamp
A microscope used to study the eye using a narrow beam of light. Used to rule out any significant corneal abnormalities such as scarring or the presence of a cataract. Further reading
Soft contact lenses
These should be removed before the laser eye surgery treatment and the consultation for a set amount of time depending on type of contact lens. Lenses can affect the surface of the eye. We require the most accurate refraction when the patient attends with a view to having laser eye surgery. If the lenses are not left out of the eye for long enough, treatment can be postponed.
Sphere (SPH)
A type of lower order aberration associated with myopia or hyperopia. See Aberrations.
Spot scanning laser
A medical instrument that produces a powerful beam of light that is focused at close range to remove corneal tissue. Spot scanning lasers use radar technology to track the eye's movement.
Strabismus or Squint
Condition in which the eyes are not both directed toward the same point simultaneously. Strabismus occurs when eye muscles are not working together properly. It is most commonly an inherited condition, but may also be caused by disease or injury. If diagnosed early, strabismus can usually be corrected. The condition may be treated with corrective eyeglasses, eye-muscle exercises, eye surgery, or a combination of these approaches. Young children with this condition may need to wear an eye patch over their stronger eye to force their weaker eye to function correctly. Children whose strabismus is not corrected may develop amblyopia. Patients who are happy with their sight with contact lenses or specs can be considered for laser eye surgery. Further reading
Stroma
Thickest part of the cornea (450-600 microns - approximately .5 millimeters). Between Bowman's membrane and Descemet's membrane.
Stye
This appears as a small lump on the inner or outer surface of the eyelid. Patients are advised to wait until the inflammation has cleared before undergoing laser eye surgery. Further reading
