Glossary of Lasik Laser Eye Surgery Related Terms F-H
See Fellow of the American College of Surgeons.
Common term for hyperopia.
See Food and Drug Administration.
Flap & Zap
Slang term for Lasik.
An infrared range laser that delivers pulses of energy within the cornea, causing a small controlled explosion of gas that separates
the layers of the cornea. The femtosecond laser for ophthalmology use on
the eye is manufactured by Intralase and is used to create a Lasik flap in a procedure commonly called Bladeless Lasik or "all laser Lasik". Detailed Femtosecond Bladeless Lasik Information
A test to examine blood vessels in the retina, choroid, and iris. A
special dye is injected into a vein in the arm and pictures are taken as
the dye passes through blood vessels in the eye.
A tiny amount of a fluorescein dye is placed in the tear film. The color
will make microscopic dots appear where the eye has become dry.
Excessive staining is an indication of dry eye.
This is a method of applying excimer laser energy. Rather than applying
all excimer energy in a broad-beam across
the entire ablation area, or the energy in variable spots sizes across the ablation area, a very small spot of
excimer energy is applied in rapid succession at different locations
across the ablation area.
Focusing Power Of The Eye
As light enters our eye, it must be brought to a focus on the retina in
order to perceive a clear image. About two thirds of the focusing power
of the eye comes from the cornea, the rest comes from the lens inside
the eye. As the light enters the eye, it is focused a fixed amount by
the cornea. As the light passes through the pupil, the lens then adjusts
the focus a variable amount with the exact amount of focusing power
applied dependent on the distance of the object being viewed. Objects at
near like a book or knitting require more power than distance objects
like movies or traffic signs.
Food and Drug Administration
The federal agency of the United States government responsible for the
evaluation and approval of medical devices. The FDA does not evaluate
surgical procedures that to not require a new medical device. Click for Important FDA Links or Click here to go to Main FDA website.
The central part of the macula that provides the sharpest vision.
Molecules that have been implicated as one causative factor in the
stimulation of abnormal cellular reproduction (cancer) and cellular
Endothelial Cell Dystrophy.
Functional Visual Disability
The degree to which a visual error interferes with a person's ability to
perform normal daily activities, such as reading, driving at night, or
The interior lining of the eyeball, including the retina, optic disc,
and macula. This portion of the inner eye can be seen during an eye
examination by looking through the pupil.
See refractive surgery complications glare, arc, starburst, and halo.
This is a profile of how excimer energy is applied. Used primarily on
flying spot lasers, more energy is applied to the center of the spot
than at the outer edges.
This is a common term for diplopia, or double images. If you look at a clock and some
of the numbers have a lighter ghost image just off to the side, this is
ghosting. Detailed Double Vision and Ghosting After Lasik Information
A disease characterized by increased pressure within the eyeball. more
If not diagnosed and treated, glaucoma may lead to optic nerve damage,
loss of visual field, gradual vision impairment, and sometimes
A diagnostic procedure using a mirror/lens device placed directly upon
the cornea that is used to view the drainage area through which aqueous
fluid exits the eyeball.
Gray Box Laser
Common term used for a laser imported from outside the United States.
This type of acquisition is not approved by the FDA. Detailed Counterfeit Lasik Laser Information
A known complication of refractive
surgery that causes images from light sources to blur with circles
radiating out from the center. Halos also occur naturally without
Extensions of plastic from the lens portion of an intraocular lens (IOL) that position and center the IOL within the
An opacification or cloudiness of the normally clear cornea. Any build
up of inflammatory infiltrates (white blood cells), extra moisture, scar
tissue, or foreign substances (like drugs) can cause a clouding of the
Health Maintenance Organization
A medical or vision insurance plan that requires beneficiaries to use
only the facilities and physicians who have contracted with the plan to
provide services to beneficiaries. Care provided to a patient by a
facility or physician that is not contracted by the Health Maintenance
Organization is not normally a covered benefit of the plan, except in
some emergency situations or with prior authorization from the plan.
Day blindness. Often caused by clouding or opacity of one or more of the
normally clear ocular tissues.
Higher Order Aberration
A common eye examination and refraction evaluates low order aberrations
(LOA). These are commonly called sphere (myopia or hyperopia) and cylinder (astigmatism).
Only a wavefront diagnosis is able
to measure high order
aberrations (HOA), which are beyond simple sphere and cylinder. HOA
are represented in mathematical calculations and are therefore infinite.
The more common of these mathematical calculations are Zernike polynomials and have names like spherical aberration, coma,
trefoil, and secondary astigmatism. Ophthalmology only deals with about
the first eight levels of HOA as represented in Zernike.
See Health Maintenance Organization.
See Higher Order Aberration.
Humanitarian Device Exemption
A Humanitarian Device Exemption from the Food and Drug Administration authorizes the use and marketing of a
device that is intended to benefit patients in the treatment of
conditions that affect fewer than 4,000 individuals.
Also known as farsightedness or longsightedness. Hyperopia occurs when
the eyeball is too short from front to back, or the eye's focusing
mechanism is too weak, causing light rays to be focused behind, rather
than on, the retina. People with hyperopia have difficulty seeing
objects close up. This refractive abnormality requires a plus (positive
or convex) lens for correction. Hyperopia is significantly more
difficult to correct with refractive surgery. Detailed
Hyperopia (Farsighted/Longsighted) Lasik Vision Correction Information
Environment with a decrease of atmospheric pressure, such as at high
A deficiency of oxygen supply to a tissue.
Looking For Best Lasik Surgeon?
If you are ready to choose a doctor to be evaluated for conventional
or custom wavefront Lasik, Bladeless Lasik, PRK, or any refractive surgery procedure, we recommend you consider a doctor who has been evaluated and certified by the USAEyes nonprofit organization.
Locate a USAEyes Evaluated & Certified Lasik Doctor.
If this article did not fully answer your questions, use our
free Ask Lasik Expert patient forum.
Recent Lasik Medical Journal Articles...