Lexique

These are photoreceptors made of nerve cells located in the retina that detect light rays and transmit them as nerve signals to the brain. They ensure quality vision in dimly lit environments but cannot distinguish colors.

The optic chiasm plays an important role in visual perception as the part of the brain where the two optic nerves cross, allowing visual information from the retinal nerve impulses to be transmitted to the occipital lobe. Each retina is divided into two hemiretinas (one internal nasal and one external temporal). The optical paths of the nasal hemiretinas switch sides at the chiasm.

Acting as a barrier, eyelashes protect the eyes by keeping impurities and foreign bodies like dust on the edge of the eyelids, preventing them from entering the eye. They also retain water, sweat drops, and attenuate sunlight for optimal vision protection.

The cornea is the transparent part located at the center, in front of the eye. Shaped like an oval, it plays a very important optical role by focusing images on the retina along with the lens. The cornea has no blood vessels to maintain its transparency and is moistened by external tears and internal aqueous humor. Because it has little resistance against bacteria and viruses, the cornea is fragile. Scratches and lacerations are injuries to the cornea’s superficial layer caused by foreign objects, rigid contact lenses, baby nails, or paper.

Normally transparent, the lens is an optical component located behind the iris, responsible for key visual system functions. It ensures visual quality focusing (accommodation), allowing image focus and convergence on the retina, and absorbs part of the UV rays to protect the retina. The lens changes shape based on object distance. For nearby objects, it curves; for distant objects, it flattens, ensuring optimal visual quality. Aging can lead to certain ocular diseases such as presbyopia (loss of elasticity) or cataracts (loss of transparency).

The fovea is a shallow depression located in the center of the retina near the eye’s optical axis. It ensures central vision, allows for precise detail perception, and enables color distinction because it contains more than 50,000 photosensitive cells (cones). Damage to the fovea can cause vision loss and color perception impairment.

An organic structure made of biological tissues and nerve cells located in the retina. Nerve ganglia form a connection between the nerve fibers, transmitting messages from rods and cones to the brain.

The lacrimal system consists of various components that enable tear formation, their distribution over the eye’s inner surface, and their drainage, keeping the eyes moist. Tears are fine drops of salty water that clean and protect the eyes from dust. If mucus, infection, or inflammation is present, the process is disrupted, causing dry eyes.

The eyeball is the vision-receiving organ that captures light signals before transmitting the information to the brain in various forms and colors. It consists of different regions ensuring its visual function, such as the vitreous body, the lens, and the aqueous humor.

A transparent liquid continuously filtered and renewed to maintain the pressure and shape of the eyeball. It plays an important role in regulating intraocular pressure.

The optical power of a lens needed for near vision, added to the power required for distance vision.

The power of the lens needed to correct various eye disorders and achieve optimal visual acuity of 10/10. The two eyes may have different needs, so it’s normal for prescriptions to specify different corrections.

A measurement used in optics to determine refraction capacity when light rays change path as they pass through a natural medium like the eye or an artificial one like glasses lenses. Higher diopter values indicate greater correction due to more significant visual impairment.

Pupillary distance is the measurement in millimeters between the two pupils. In eyewear, the half-pupillary distance is measured, corresponding to the distance between the nose bridge and the pupil (half the pupillary distance). This measurement allows the lens to be centered and aligns the optical center of the lens with the pupil.

Lens height is an essential measurement for progressive lenses and some single-vision lenses. It can be accurately measured by a vision professional.

A prescription is a document provided by your optometrist containing specific details about your visual health. It must be less than three months old to be valid.

Ocular pressure, also known as intraocular pressure, exists inside the eyeball and is maintained by the balance of aqueous humor production (which provides necessary nutrients to the iris, lens, and cornea) and its drainage. Elevated intraocular pressure is a primary factor in glaucoma, which damages optic nerve fibers and causes vision loss.

Optical power is a characteristic of a visual instrument that defines the ability of a lens or contact lens to correct visual impairment. The greater the lens curvature, the higher the degree of correction and refraction. Optical power is measured in diopters.

Also known as ‘UV rays,’ ultraviolet radiation consists of UVA and UVB rays from the sun. Sunlight is harmful to eye health and can damage certain functions if your eyes are not adequately protected.

Ultraviolet radiation (UV) is electromagnetic radiation similar to visible light, but its wavelengths, ranging from 20 to 400 nanometers (a billionth of a meter), are too short for the human eye to detect. Shorter wavelengths are more harmful. UV rays penetrate the ozone layer and can cause various health issues over time, including cell aging.

Often called ‘lazy eye,’ this vision disorder results in a partial or relative loss of visual acuity. It is caused by poor transmission of light rays captured by the eye to the brain.

Deviation of light rays causing poor image transmission to the retina. It results from an imbalance between the eye’s refractive power and shape, leading to unclear images for near or distant objects.

Different perception of images between the two eyes, regardless of the distance to the object. It occurs when one eye sees less clearly than the other.

Caused by a cornea that is not perfectly round, resulting in an oval shape that deforms or stretches perceived images regardless of distance. Instead of focusing on a single point, light rays spread to different points in front and behind the retina, causing these distortions.

Inflammation of the eyelids caused by glands behind the eyelashes, often chronic and recurring. Symptoms include red, itchy, and irritated eyes.

Characterized by repeated and involuntary contractions of the eyelid muscles. Severe cases may result in the inability to open the eyes, worsened by fatigue, bright light, or anxiety.

Better known as myopia, this visual impairment occurs due to an imbalance between the eye’s length and the curvature of the cornea or lens. It results in images of distant objects forming in front of the retina, causing blurred vision for far objects while maintaining clarity for near ones.

A cataract is a clouding of the eye’s natural lens, leading to progressively reduced vision. Normally transparent, the lens becomes opaque, making vision difficult. Causes include aging, injury, heredity, disease, excessive sun exposure, or medication use.

Blindness refers to partial or total loss of visual capabilities due to conditions like cataracts, glaucoma, macular degeneration, or diabetic retinopathy. Early identification and management can help limit complications.

Conjunctivitis is a common inflammation of the conjunctiva, the thin membrane covering the eyelid’s interior and part of the eye. It can be caused by infections, allergies, or chemicals and results in red, irritated eyes.

Floaters appear as black dots or semi-transparent filters in the visual field, caused by small particles in the eye’s vitreous gel. They cast shadows on the retina, noticeable as they drift during eye movement. Aging, injuries, and eye diseases are common causes.

Color blindness occurs due to functional issues in one or more retinal cone cells responsible for color perception. Causes include genetic factors, nerve or brain lesions, or chemical exposure.

The modification of the curvature of the lens rays, allowing clear vision regardless of the distance of the observed object.

Visual acuity is the eye’s ability to distinguish an object at the longest possible distance.

Visual acuity describes the ability of the eye to distinguish between two distinct points. For distance vision, it’s the ability to discern a small object located as far as five meters away. It is measured using drawings or letters (optotypes) during an eye examination.

The visual field refers to the peripheral space that an eye can perceive while fixing on a stationary point. Normally, it spans 60° upward, 70° downward, and 90° laterally, encompassing a 180° visual field. Factors contributing to decreased visual field include vision disorders, injuries, accidents, or eye diseases. A visual field exam helps detect and monitor the progression of diseases like glaucoma, which can impair vision and lead to blindness if untreated.

Convergence is a reflex linked to the accommodation mechanism, allowing both eyes to fixate on the same point in close vision sharply. This ability enables depth perception through ocular coordination. A convergence deficit disrupts this coordination, causing eye misalignment, double vision, fatigue, and headaches.

The eye’s adaptation to changes in brightness. In darkness, the retinal rods, not the cones, function to maintain a certain level of visual quality.

The eye’s ability to adjust to different environmental settings and varying focal distances of light rays associated with blurred vision.

A 15/15 vision denotes normal acuity at 15 feet, similar to 20/20 being a sign of normal acuity at 20 feet. Most optometrists express visual acuity using the 20/20 standard.

A 20/20 vision indicates normal visual acuity or clarity at a distance of 20 feet. A 20/60 vision means being able to see at 20 feet what others can see at 60 feet. Other visual functions, such as peripheral vision, ocular coordination, depth perception, and color distinction, are equally important for overall vision ability.

Peripheral vision is an essential aspect of human vision, defined as the ability to see objects without looking directly at them. Many visual disorders can lead to peripheral vision loss, which may occur suddenly or gradually without noticeable symptoms. Causes include minor issues like ocular migraines or vitreous floaters to severe ones such as retinal detachment, glaucoma, strokes, or optic nerve damage.

Stereoscopic vision, or depth perception, is the ability to see objects in three dimensions. Thanks to binocular neurons in complex brain mechanisms, these are the only neurons receiving nerve signals that allow three-dimensional vision from two images perceived by each eye. Vision can be impaired in cases of severe damage to one eye due to amblyopia, diplopia, or strabismus.

Acetate, also known as cellulose acetate, is a synthetic plastic material. This plastic material is known for all the advantages it offers. It is biodegradable and allows the use of a wide range of colors. Moreover, this material is easy to work with heat and is tolerated by all skin types. This explains why it is often used for manufacturing high-quality glasses.

Surgical steel is a material resulting from the fusion of steel and titanium. This alloy is ultra-lightweight, flexible, and robust. Glasses designed with surgical steel are highly resistant to shocks, corrosion, and heat.

Stainless steel frames, also called inox frames, are lightweight and strong. They have characteristics similar to those of titanium but are generally less expensive. They can be a good alternative to metal frames because they are hypoallergenic.

This is a metal alloy (often titanium and nickel) used in the manufacturing of optical frames. This alloy is robust and retains its shape.

Aluminum frames are quite rare. Indeed, this material requires a high level of technical expertise due to its numerous advantages. They are lighter than titanium frames, resistant to corrosion, and 100% recyclable.

It is possible to process the lens to reduce its thickness. This operation is called thinning.

Organic lenses are highly valued for their lightness and the comfort they provide. However, they can scratch very easily. Fortunately, it is possible to coat these lenses with a scratch-resistant varnish.

It is possible to treat optical lenses against reflections. This type of treatment consists of different successive layers that interact to reduce reflections.

Carbon frames are 10 times stronger and 75% lighter than steel. Carbon offers a great deal of flexibility in terms of shape. However, the choice of associated colors is limited.

A coating that eliminates reflections.

Prescription glasses with degressive lenses aim to make near vision more comfortable while improving intermediate vision.

Refers to a lens that corrects two vision problems at the same time, such as myopia (distance vision) and presbyopia (near vision).

Carbon fiber frames are 10 times stronger and 75% lighter than steel. Carbon offers a great deal of flexibility in terms of shape. However, the choice of associated colors is quite limited.

Nylon fiber is an alternative to acetate frames that retains the lightweight aspect of the frame and is available in a wide range of colors and styles.

Deviation of light passing through a transparent material to improve the optical capacity of the eyes. The higher the index, the greater the deviation of light, and the thinner the lens will be to allow an equal refractive power.

Frames made of metal are made of an alloy such as monel, titanium, or nickel silver.

This is a type of lens that is heavier and less resistant; however, it does not scratch and is thinner than an organic lens of the same type.

A component made from nickel and copper used in the development of lightweight and corrosion-resistant metal frames.

Injection molding is a process used to shape nylon or plastic.

The alloy of nickel and zinc forms nickel-silver. This type of alloy is very rigid, which is why it is often used in the manufacture of hinges, end pieces, and bridges.

Organic lenses are widely used in the optical world. Made from resin, they are very strong and lightweight. However, they remain sensitive to scratches.

These lenses darken or lighten depending on light intensity (exposure to ultraviolet light).

A type of material that is often used to refer to acetate or nylon.

Polarized lenses eliminate glare. They greatly improve comfort in places with strong reflections such as at sea or on the road.

This material is a type of thin, high-index plastic. It is lightweight and resistant.

Progressive lenses are intended for people with presbyopia and provide clear vision at all distances.

The lens power refers to the corrective strength of the lens.

Colloquial term for photochromic lenses.

Refers to the addition of a protective layer: scratch-resistant, anti-reflective, or hydrophobic.

Protective layer against physical damage to the lens such as scratches.

A coating that protects the lens against water.

A single correction throughout the entire lens.

Tint is a coloring of the lens that protects the eye against external light aggressions.

Refers to a high-end, lightweight metal. This material is very robust and highly resistant to corrosion.

Colloquial term to refer to progressive lenses.

Glass was the most used material in the manufacturing of optical lenses before the arrival of plastics.

High-index lenses are very thin and lightweight, and have increased refractive properties.

Thinned lenses refer to lenses that have been slimmed down.

Lenses designed based on the digitization of your eyes. Personalization is therefore tailored only to your eyes.

Lenses made of silica and a mixture of oxides melted at high temperatures. These lenses are heavy and can break. However, they resist scratches.

Lenses that correct two vision problems at the same time.

Organic lenses are more resistant than mineral lenses and better withstand impacts. However, they need to be treated to be scratch-resistant.

A photochromic lens is capable of changing its tint depending on the amount of ultraviolet it is exposed to.

This is a versatile sun lens that filters reflections while enhancing details, colors, and depth perception.

Polycarbonate lenses are thinner and lighter than plastic lenses.

Refers to lenses that provide up to three optical powers in a single lens.

Refers to a lens that corrects a single vision problem.

Colloquial term for an eyeglass lens.

Centering is a step aimed at aligning the center of the eye with the optical center of the lens, ensuring visual comfort.

Retinal imaging is a tool that allows healthcare professionals to make an early diagnosis and prevent certain diseases.

The assembly of a pair of glasses represents the assembling of the different parts.

Through the effective diameter, the shape of the frame, or pupillary distances, pre-calibration is a lens thinning process reserved for hyperopes.

Refraction is the property of light to change direction when it passes from one medium to another with a different density. It is therefore a change in the direction of radiation so that it reaches a single fixed point, namely the retina.

A refractometer is a device that allows automatic measurement of the refraction of an eye, thus the power, thereby detecting various vision disorders such as myopia, hyperopia, astigmatism, and presbyopia. With this test, the optometrist will be able to find the appropriate lens to correct your vision.

Standards correspond to legal requirements.

A medical specialist of the eye, the ophthalmologist’s main function is to diagnose various eye pathologies and treat them using treatments, medications, or surgical interventions adapted to the eye disease. With their training, they can perform complete evaluations of visual function and offer specific eye care to each patient, referred by an optometrist.

A visual professional and expert in visual orthoses, they are responsible for evaluating ocular-visual needs in addition to having the required certification to sell or adjust ophthalmic lenses, prescription glasses, sunglasses, contact lenses, or any other optical instrument aiding vision and eye health. This knowledge allows them to manufacture, adjust, and repair your glasses according to prescriptions given by a certified optometrist or ophthalmologist. An optician is not the one who evaluates, diagnoses, or treats your visual problems, but rather the one who ensures that your visual instrument is adapted to your situation.

This visual professional is a major player in eye health care, taking charge of eye exams and screening for visual problems such as visual acuity, astigmatism, myopia, hyperopia, etc. Along with the ophthalmologist, the optometrist evaluates, diagnoses, and treats visual impairments in addition to being responsible for the sale of ocular instruments such as prescription glasses, sunglasses, and contact lenses. They can also treat eye pathologies like conjunctivitis as well as minor emergencies such as foreign bodies.

This branch of ophthalmology is a paramedical practice that allows the prevention and rehabilitation of visual disorders such as strabismus, amblyopia, or ocular motor paralysis. They interact with other important medical specialists such as opticians, ophthalmologists, occupational therapists, and psychomotor therapists.

A traditional teardrop shape that made the Ray-Ban brand famous.

The brow bar is the part located between the two optical lenses.

Pince-nez are glasses without temples. However, this term can also refer to glasses in colloquial language.

Refers to the two rounded ends that wrap around the ears.

The pad arm is the piece that allows you to fold the temples of your glasses.

A brushed finish denotes a soft texture rather than a polished one for metal frames.

Curved frames are not suitable for all types of vision and correction. These frames are associated with highly curved lenses, whose angle relative to the frontal plane can reach up to 25°.

Square-shaped glasses

The hinge is the part of the frame that connects the rim to the temples. This mechanism allows the temples to unfold and fold.

To give a vintage look, rivet hinges are fixed to the front and use twin holes.

They are used for acetate or nylon frames and are made of nickel and silver.

This type of hinge uses an internal spring to improve strength and flexibility.

A type of hinge made of flexible titanium.

Type of hinge made from a single block of metal.

Refers to a frame where the lens rim is only half-covered.

The groove is a channel designed in the frame to hold the lens in place.

Refers to the general appearance of the frame. Eyewear designers create frames for all tastes and lifestyles.

Curved frame that is not suitable for all types of vision

Bezel is a term that refers to the piece that holds the lens in place and varies greatly from one model to another.

Glasses shape with sharp angles

Refers to a reference code printed inside the temple. The frame identification provides information such as brand, model, color, temple length, and size.

Also known as drilled frames, the term “invisible” refers to a type of eyeglass mounting.

Glasses intended to relieve visual fatigue without correcting vision.

Glasses with lenses that protect against ultraviolet rays

Refers to a non-shiny surface used for coloring metal and acetate frames

Refers to the material from which the frame is made.

The monocle is the old version of glasses and was worn on only one eye.

Refers to the overall structure that allows optical lenses to be placed on your nose.

This is a type of eyeglass mounting consisting of a metal part and a nylon thread part.

Refers to a classic feminine style with a contoured rim.

Elongated horizontal shape with rounded curves

A glasses shape often suited for women with long lenses on the sides and short in the center

Refers to the entire front part of the frame.

Colloquial term for nose pads.

This is a type of eyeglass mounting. Using nuts or silicone bridges, the frame and lenses are discreetly connected. They are also called ‘invisibles.’

A rectangular silhouette with curved edges making the lines softer and more feminine.

Nose pads are soft plastic cushions located on each side of the nose.

Refers to a frame where the lens rim is fully covered.

The bridge is the part that joins the optical lenses and distributes the weight evenly on the nose.

Double part that joins the two optical lenses and provides better frame robustness.

The groove is carved into an organic lens for a nylon-type frame.

Rectangle-shaped glasses

Retro is a vintage style characterized by round shapes, rivets, or even metal.

Round-shaped glasses

Refers to a frame where the lens rim is not covered at all.

It’s a trend that involves wearing glasses whose frame is oversized relative to the face.

Asian fit is designed for faces with high cheekbones. The curves and the bridge are minimalist.

The temples refer to the side arms of the glasses.

Connects the front of the glasses to the temples

Refers to an old-school style characterized by tortoise patterns, metal, or even round or square shapes

It’s a digital lens whose characteristics provide optimal clarity and detail. This type of glasses is suitable for high-index prescriptions.

Refers to a coating that repels water and sweat.

Refers to a tint that protects against the sun’s UV rays.