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Glossary of Lasik Laser Eye Surgery Related Terms - M-O

Numbers A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Macro Striae
Wrinkles in the Lasik flap. Detailed Lasik and Bladeless Lasik Flap Macro Striae (Wrinkles)
The small, sensitive area of the central retina; provides vision for fine work and reading.
Macular Edema
The collection of fluid in and under the macular portion of the retina causing swelling.
Manifest Refraction
An examination of the eye to determine refractive error while the natural crystalline lens is able to accommodate.
Most older technology excimer laser machines employ different kinds of masks to customize, refine, and smooth the corneal surface. Many machines have an internal constricting diaphragm (like a camera f-stop mechanism) as an internal mask. Variable rotation of the masks is used to deal with astigmatism.
See Medical Doctorate.
Nasal or towards the nose.
Medical Doctorate
A certificate affirming that the holder has achieved the training required to be a medical doctor through a school of medicine.
A shortened name for Aesculap-Meditec.
Meibomian Glands
Large specialized sebaceous glands in the eyelid. There are about 50 glands on the upper lids and 25 glands on the lower lids. They create and distribute an oily substance called lipids. Meibomian gland secretions help keep the eye moist. When blinking, the upper lid comes down, presses on the oil and pulls a sheet of oil upwards, coating the tear layer beneath to keep it from evaporating.
Meibomian Gland Dysfunction
See Meibomitis
A dysfunction of the meibomian glands that provide an oily film over natural tears to keep them from evaporating too quickly. Detailed Meibomitis and Lasik Dry Eye Information
Mesopic Pupil Size
The size of a pupil under medium light conditions such as daylight or a well lit room.
Micro Striae
Also called Bowman's Crinkles. Very small wrinkles in the flap caused by Bowman's layer constricting. Detailed Lasik and Bladeless Lasik Flap Micro Striae (Wrinkles)
A unit of length equal to one-millionth of a meter.
A surgical device for creating a flap of corneal tissue used in Lasik and some transplant techniques. There are two classes of microkeratomes: mechanical and laser. Both are affixed to the eye by use of a vacuum ring, flatten the cornea with a clear applanation plate, then cut across the cornea under the plate.
The mechanical microkeratome uses a very sharp and thin metal blade. The femtosecond laser microkeratome uses amplified light energy to cause tiny bubbles to form at a predetermined depth. Thousands of these bubbles next to each other create an incision. See Bladeless Lasik.
Abnormally small size of eye.
A nanometer, or 10 to the -9 power meter. The term millimicron was used before 1967.
Pupillary constriction.
Involving one eye.  As example, monocular polyopia is when a person sees multiple images in one eye.
A technique to limit the effects of presbyopia by correcting one eye for near vision and the other for far vision. Detailed Lasik Monovision Article
Munnerlyn Formula
Named for engineer Charles R. Munnerlyn, Ph.D, who pioneered the technology for vision correction based on the excimer laser. This is the basic formula to calculate the amount of tissue that needs to be removed to affect refractive change. Detailed Laser Tissue Removal Calculation Information
Pupillary dilation.
Also known as nearsightedness or shortsightedness. Myopia occurs when the eyeball is too long from front to back, or the eye's focusing mechanism is too strong, causing light rays to be focused in front, rather than on, the retina. People with myopia have difficulty seeing objects far away. This refractive abnormality requires a minus (negative or concave) lens for correction.
Abbreviation is nm. 10 to the -9 power meters. The term nanometer has replaced the term millimicron that was used before 1967.
Toward the nose.
National Committee for Quality Assurance
An independent, non-profit organization that certifies credentials verification organizations and accredits managed care organizations. 
National Eye Institute
A division of the US federal government's National Institutes of Health. Approximately three-fourths of US eye research funding originates at the National Eye Institute. 
See National Committee for Quality Assurance.
Near Point Of Accommodation
The closest point in front of the eyes that an object may be clearly focused.
Near Point Of Convergence
The maximum extent the two eyes can be turned inward.
Common term for myopia.
NearVision CK
Trade mark for the use of CK to restore near vision for individuals with presbyopia. The technique is similar to monovision. Detailed y CK Information
See National Eye Institute.
The formation of new blood vessels, often fragile and inappropriate for the location. Long-term use of contact lenses can starve the cornea of oxygen, causing neovascularization as the body attempts to provide oxygen through blood vessels.
Nuclear Sclerosis
Commonly known as cataracts. Nuclear sclerosis is an opacity or clouding of the natural crystalline lens that may prevent a clear image from forming on the retina. Cataracts occur naturally and can be induced by trauma. The cataractous lens may require surgical removal if visual loss becomes significant, with lost optical power replaced with an intraocular lens.
Ophthalmic equipment company. 
Night Blindness
Common term for nyctalopia.
Night blindness. Often caused by a deficiency of the retina due to a lack of vitamin A.
An eye condition characterized by rapid, jerky eye movements. Nystagmus details.
Ocular Hypertension
Elevated intraocular pressure.
Ocular Rosacea
The cause of ocular rosacea is not understood but its symptoms can leave the eyes feeling irritated and "gritty". Patients may experience redness, tearing or crusting on the lashes. See Ocular Rosacea Details
Off Label Use
A term used for procedures that are legal, but are not specifically approved for a particular device or drug. An example is Lasik. The excimer laser is FDA approved for PRK, but not for Lasik, which is a combination of ALK and PRK. The Lasik procedure comes under the definition of the practice of medicine (also called scope of practice), so the FDA does not necessarily need to approve the use of the excimer laser specifically for Lasik. An easier example is the scalpel. The scalpel is not specifically approved for all procedures that may require a scalpel, but if a medical doctor determines the use of this FDA approved tool is appropriate, then it is okay with the FDA. Some excimer lasers have received FDA approval specifically for Lasik, but this is more for marketing purposes than to accommodate any legal requirement.
Anything to do with the eye.
Ophthalmic Imaging Systems
Ophthalmic equipment company. 
A medical doctor who specializes in the diagnosis and medical or surgical treatment of eye diseases. To become an ophthalmologist one must first obtain a medical degree (M.D. or D.O. in North America) and then complete further specialty training. A medical degree typically takes 7 or 8 years university training and a specialist certification an extra 3 years in the USA or 4 years in Canada. Specialist MD's are usually divided into "medical" and "surgical" disciplines. Ophthalmology is technically a "surgical" discipline. Some ophthalmologists chose not to perform surgery and can be called "medical ophthalmologists". An ophthalmologist may also prescribe eyeglasses and contact lenses. Visit ophthalmology, optometry, and opticianry, to compare the three disciplines of eye care.
Examination of the internal structures of the eye using an illumination and magnification system.
Optic Cup
The white, cup-like area in the center of the optic disc.
Optic Disk
The circular area (disc) where the optic nerve connects to the retina. Also know as the optic nerve head.
Optic Nerve
The optic nerve is a bundle of nerve fibers, about the diameter of pencil, which passes through the back of the eyeball and connects to the nerve fiber layer of the retina. It can be observed directly with an instrument called an ophthalmoscope. The optic nerve carries the visual messages from the photoreceptors of the retina to the brain.
Optical Ablation Zone
The area of the cornea where the excimer laser ablation fully corrects refractive error. See also transition zone.
Optical Zone
The area of the eye through which light passes to the retina. To reach the retina light must pass through the cornea, aqueous humor, crystalline lens, and vitreous while passing through the pupil. The optical ablation zone is the area where a laser has created full refractive error correction. See also Transition Zone.
An expert in the art and science of making and fitting glasses. The optician may also dispense and/or fit contact lenses, depending on local licensing practices.  Visit ophthalmology, optometry, and opticianry, to compare the three disciplines of eye care.
A doctor of optometry is a non-medical primary eye health care provider who specializes in the examination, diagnosis, treatment, management, and prevention of diseases and disorders of the visual system. Optometrists today most often complete a bachelor of science degree (with very specific requirements) followed by an optometry degree program that requires four to eight years to complete. Patient contact begins in the second professional year with the final year being a full 12-month internship. Many optometrists include the provision of contact lens and spectacle devices as part of their daily practice. The optometrist may also prescribe medications, depending on local licensing practices. Visit ophthalmology, optometry, and opticianry, to compare the three disciplines of eye care.
A non-surgical procedure using contact lenses to alter the shape of the cornea to effect a change in the refractive error.
Also know as the "globe", the structural area of the facial skeleton into which the eye is set.
A known complication of refractive surgery where the expected amount of correction is more than desired. Overcorrection often occurs where healing regresses less vigorously than predicted. See Overcorrection Details

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