Archive for June, 2007

The extrinsic muscles and their actions

Friday, June 29th, 2007

information on eye movementsAssociated actions can also be found between the eye muscles and those of the eyelids: there is a concordance between the eyelid’s elevator and the vertical straights that keep almost constant the aperture of the eyelids when the eye is moved up or down. An associated action is also found between the straight internal eye muscles and the eyelid muscle when accomodative and converging.

Also the eyelid’s constrictor and the sphyncter of the iris act in strict association determining an accomodative myosis. A certain relation exists between the straight inferior and the accomodative mechanism; in fact, it seems that the accomodation is caused by a downward movement.

From Optometria e oftalmologia by prof. Sergio Villani.

CARRERA: 1956-2006: A WINNER FOR 50 YEARS

Tuesday, June 26th, 2007

a winner for 50 years

IN THE SECTOR OF SPORTS EYEWEAR AND SKI HELMENT AND GOGGLES

The history of the CARRERA trademark in the sector of sports eyewear and ski helmets and goggles starts many years ago in 1956. It is the story of an extraordinary adventure in both eyewear and in sports, combining enthusiasm, innovation and success.

Its name comes from the “Carrera Panamericana”, an automobile race that used to go all the way across Mexico. In 1996 CARRERA joined the Safilo group, a market leader in sunglasses and prescription frames. At this time Safilo started producing ski masks and helmets, presenting CARRERA’S  innovative, advanced products in this market as well. ‘Great enthusiasm for sports and the desire to be number one – always’ is the philosophy behind CARRERA. Over fifty years of victories in the most exciting sports is proof of the commitment that CARRERA, through its glasses, masks and ski helmets, devotes to innovation and research for winning performance.

Today the CARRERA brand occupies one of the top positions in the history of sport. The finest athletes choose only the finest products and that is why CARRERA is the brand of the champions where technology, performance and design play a decisive role. CARRERA is number one in the world of skiing, with prestigious victories from its athletes who took part in the Winter Olympics in Turin 2006. In the world of motorcycle racing, CARRERA, who is the co-sponsor of the LCR team of Lucio Cecchinello, is first choice with champions like Casey Stoner in the “GP Motorcycle” class and with testimonials such as Hector Barbera, Jorge Lorenzo and Mika Kallio. CARRERA is also a big fan of rugby and sponsors the CARRERA PETRARCA RUGBY team of Padua, Italy. Triumphs are also boasted in the recent years in sports such as canoeing, bicycle racing and mountain bike competitions.

Being a leader means staying a step ahead of the times. This is the spirit that CARRERA has always shown, offering advanced products as a way of life and launching sunglasses, prescription frames, ski helmets and masks that are always at the top of the range. CARRERA products are designed and developed in collaboration with the athletes who use them in order to ensure constant improvement of the quality level.

CARRERA over the years has taken full advantage of the experience of SAFILO, the name that for 70 years has meant the best in eyewear all over the world. Today CARRERA is synonymous with technology, safety, innovation and design.

Carrera eyewear catalogue 

Source: Carrera press releases

SAFILO INTRODUCES HUGO BY HUGO BOSS

Saturday, June 23rd, 2007

Padova, 30 april 2007 – The Safilo group, world leader in high-class and luxury eyewear, presented in Milan the first collection of the HUGO line by Hugo Boss at the MIDO, the primary international exhibition in the optical sector (Milano, 4-7 may 2007).

Inspired by the innovative concept of “industrial design”, the new eyewear collection puts the spotlight on new generation eyewear. Eyeglasses frames in minimal style and vintage-style sunglasses, interpreted in a contempory key, are combined to create a determined and distinctive look. The refined chromatic range and the materials of superior quality reflect the brand’s spirit, between unconventional contrasts and its post-modern mood.

The female sunglasses fascinate with their new and unexpected proportions: the ample square shapes are in titanium and betatitanium, very light and anallergic materials, are completed with very thin temples on which the brand is shown. The chromatic gamma plays with soft tonalities of palladium with grey lenses, dark rutenium with blue aviator lenses, rutenium with green or brown lenses, brown with polarizing lenses in the same colour for a maximum eyesight.

Traces of the 70s in the male sunglasses in metal or titanium. The aviator line are re-interpreted in an ultra-modern key, with ample lenses and the temples terminated in acetate, shaped like an arrow, which is the leitmotiv of this collection. The HUGO logo appears on the initial part of the temples, discretely playful in tonalities of black opaque, palladium, bronze which combine perfectly with fumé or grey lenses.

A contemporary mood are the characteristics of the male eyeglasses frames for a sophisticated man: realized in ultra-slim betatitanium profiles, the new silhouettes distinguish themselves through important volumes and the extra-large lines of the temples, customized by the brand laser-carved in the temples, The chromatic palette shows interesting combinations of shiny and opaque tonalities, in the nuances of shiny black-copper, dark-rutenium, dark-gold rutenium, grey-blue. Other fascinating proposals for the male eyeglasses line distinguished by decisive lines: contrast between ample volumes and thinness underlined by classic colours like red-havana, striped havana and black on which the logo is carved.

The HUGO by HUGO BOSS will be distributed in the HUGO BOSS boutiques and in the most exclusive optical shops.

The Safilo group is leader in high-class eyewear and at the world’s top in the eyeglasses, sunglasses and sport sector. Present on the world market through exlusive distributors and 30 branch offices in the U.S.A., Europe and Extreme Orient, Safilo sells its collections under its own brand Safilo, Carrera, Smith, Oxydo, Blue Bay, as well as the licensed brands designed by Alexander McQueen, Bottega Veneta, Boss by Hugo Boss, Boucheron, Diesel, 55DSL, Dior, Emporio Armani, Giorgio Armani, Gucci, Hugo by Hugo Boss, Imatra, Marc Jacobs, Marc by Marc Jacobs, Max Mara, Max&Co., Oliver, Pierre Cardin, Stella McCartney, Valentino, Yves Saint Laurent. In addition, only for the US market, the collections of: Fossil, Juicy Couture, Nine West, Kate Spade, Saks Fifth Avenue, Liz Claiborne, J.Lo by Jennifer Lopez, A/X Armani Exchange and Banana Republic.

Associate and antagonist muscles

Wednesday, June 20th, 2007

Information on eye movement
All eye muscles orginate close to the nose. The vertical straight muscles, inserted on the sclera, cause abduction. If we want to rotate the eye vertically upwards, the straight superior muscle can not perform this movement alone because its action is not only upwards but also abducts to the inside.

For a direct elevation also the help of the oblique inferior muscle is needed because it causes abduction to the outside.

The action of the oblique inferior neutralizes the abduction inwards. Thus the combined effort of the two muscles turns the eye upwards.

In the same way the inferior straight muscle doesn’t only cause a depression of the eye but also the abduction outwards which is corrected by the oblique superior muscle, which abducts inwards; the combined effort turns the eye downwards.

The straight inferior and the oblique superior behave in a similar way; they are associated in the downward movement but are antagonists in other directions.

The obliques abduct with more force than the vertical straights can adduct; therefore, for the simple elevation and depression the straight vertical muscle is used assisted by an oblique muscle to neutralize lateral movements.

From the above it seems incomprehensible that each eye muscle needs others to oppose or assist:

  • The horizontal straight muscles are in each others’ direct opposition, the horizontal straights are vertically opposed.

  • The straight and oblique superiors are in horizontal and vertical opposition.

  • The straight internal and the straight vertical are associated in adduction.

  • The straight external and the obliques are associated in abduction.

  • The straight superior and the oblique inferior are associated in superduction.

  • The straight inferior and the oblique superior are associated in subduction.

From Optometria e oftalmologia of prof. Sergio Vill

Vacation time: tips for your eyes

Sunday, June 17th, 2007

Tips for the eyes

Vacation time, travel time: but what are the eye problems that can ruin a well-deserved vacation? Dr. Stefano Pintucci, ocular surgeon at the Oftalma ONLUS, has created a list that you should always carry with you.

  1. If you suffer of car sickness and need to use plasters that are applied on the neck, be aware that these plasters may cause a dilation of the pupils; inform always your doctor of their use.
  2. In the mountains and at the seaside beware of excessive sunshine: it may cause actinic keratite, i.e., an inflammation of the cornea.
  3. Don’t forget that more sun results in more rimples and eyebags.
  4. Wind and sun, but also allergies, cause “dry eyes” and “red eyes”.
  5. Excessive sun accentuate kataract and macular degeneration.
  6. Attention to insects: the puncture by a processionary caterpillar can cause you severe keratitis. Consult immediately a first-aid station.
  7. Always carry with you your own eyewash, you never know whether you can find the same product while travelling.
  8. Make sure that your sunglasses carry the CE mark and have been recommended by an optician.
  9. Always carry a spare pair of contactlenses and spare glassess.
  10. Avoid non-prescribed eyewashes.
  11. in the case of myopia, if the subject is dehydrated, it can see “flies” or flashes which could be a symptom of crystal and retina separation. Drink a lot of water!
  12. Be aware of virus in sea and swimmingpool water. Some inflammations of the cornea and congiuntiva can be caused by clamidia and acantoameba, present in swimming pools.
  13. Inform yourself of hygienic conditions in other countries.

“It is also basic - explains Pintucci - to use the vacations to have the eyes checked of your children. Now that schools are closed I dedicate myself to free checkups for children between 0-7 years: the age in which their vision is shaped.”.

The primary cause for delays in learning at school is linked to uncorrected eyesight flaws like hypermetropia, astigmatism e myopia. In the majority of cases the child does not complain because it doesn’t know better. In the presence of hypermetropia, the child may complain about headaches, burning eyes and, in some cases, doubling of the image when an object is observed from nearby.

It is important to remember that untreated eyesight flaws can cause a “lazyness” of the eye (amblyopia) resulting in more serious deficiencies. Amblyopia has to be treated as early as possible with the proper therapies (before the 8 years of age) because the brain, which processes the images, is not yet used to them and can therefore easily adjust to the treatment. An ocular visit is fundamental around the 3 years of age to diagnose or avoid refractive alterations.

At the Oftalma ONLUS Dr. Pintucci performs free preventive visits from birth to 7 years of age as a mission to fight children’s eyesight problems such as “eye lazyness”, eyesight defects, strabismus, etc…

In cooperation with the otolatryngologist Dario Granata free screening tests for allergic rhinitis are performed on children of the same age group with prescription of the most appropriate therapy.

Source: Salute Europa of 17 July 2006

The rotation of the eye (2/2)

Thursday, June 14th, 2007

eye rotation

The STRAIGHT DOWN acts similarly to the straight up and, therefore, its function is similar to that of its antagonist with the only difference that is depresses the eye and rotates the eye on its axis but to the outside (exotorsion, which can cause exocicloforia).

The THIRD PAIR consists of the oblique superior, which rotates the eye down and to the outside, and the oblique inferior, which rotates the eye up and to the outside.

The reflex part of the superior oblique in its primary position forms, with the eye’s axis at a 50 degrees angle; performs two actions: the primary of simple rotation around the optical axis, intorsion which produces incicloforia, while the secondary action of depression is one of abduction to a modest degree.

When, instead, the eye is in secondary position, abducted by 40 degrees, its action is that of simple torsion; simple depression when abducted by 50 degrees. This muscle is very important because the straight-down cannot depress the eye sufficiently when the eye is strongly abducted.

The OBLIQUE INFERIOR in primary position performs two actions: the principal of exotorsion which produces exocicloforia; one of elevation and slight abduction. In the secondary position its behaviour is like that of the oblique superior with the difference that it rotates the eye upward and externally.

The rotation of the eye is performed in small bursts unless one observes an object in motion; in that case the eyes rotate with a rapid and constant movement.

Articolo correlato: The rotation of the eye (1/2).

Da Optometria e oftalmologia del prof. Sergio Villani

Lenses that cut the “Blue”, part 4/4

Monday, June 11th, 2007

Lenses that cut the Blue

Today experiments are performed to create lenses with a sunfilter in its the center of ca. 26mm and, with that, try to protect the eye without inhibiting the surrounding skin to tan. This is a real alternative for those who have taken the bad habit to wear sunglasses that do not block the UV rays. This is extremely dangerous because reducing the luminosity the pupil enlarges, exposing a larger area of the retina to the ill effects of the UV rays. The optician therefore has the duty to warn the customer of the danger when chosing sunglasses that do not filter UV rays.

To what has been said till now. should be added that the mydriasys caused by too-dark lenses, especially when worn in a low-light environment, in certain subject may cause alterations of the endo-ocular pressure. It must also be said that a transmission factor of 50% may cause a restriction of the visual area by 15-30% for the isopterum l/1 of the Goldman perimeter, when they are used in a scarsely lit environment.

Related articles: Lenses that cut the “Blue”, part 3/4

a cura del Prof. Sergio Villani

The rotation of the eye (1/2)

Friday, June 8th, 2007

The rotation of the eye

The six eye muscles form three distinct couples in which each muscle acts with its partner; this is true for the first couple while the others are only partly antagonists.

The first couple consists of the straight external, which rotates the eye outside while the straight external rotates it inside.

Thus, when the eye is rotated to the inside, the straight internal muscle is contracted while straight external muscle is relaxed. These two muscles are also called the horizontal straights.

The second pair consists of the straight up and the straight down; the straight up in its primary position forms a visual angle of 23 degrees, therefore its primary action is to raise the eye while its secondary action is to rotate the eye internally and to adduct to a minimal degree.

The secondary position, i.e., when the eye is abducted ca. 23 degrees, its action is purely of elevation because the muscle’s moves in the same direction as the optical axis of the eye.

When the eye is adducted its main action is that of intorsion. One could say that the straight-up has two prevalent and secondary actions in positioning the eye; i.e., it is rotated outside (abduction) by 23 degrees its action is simply elevating; if it is rotated inside (adduction) by 76 degrees, its action is of intorsion.

Because they eye cannot rotate to the inside by more than 45-50 degrees, pure intorsion is practically not possible.

From Optometria e oftalmologia by prof. Sergio Villani

Lenses that cut the “Blue”, part 3/4

Tuesday, June 5th, 2007

Lenses that cut the “Blue”, part 3/4

Let’s remember, among others, that lenses that cut the blue do not improve the perception of contrast and low spatial frequencies in respect to neutral glass of the same density.

But these lenses that cut the blue are not in all aspects equivalent to the neutral lenses. They can, in fact, cause an alteration of the chromatic discrimination inducing a flaw of the type tritan, and also an alteration of the chromatic discrimination in the entire spectrum. Also the protanops and the deuteranops suffer of the use of these lenses.

It is necessary to inform, those who want to use them, of the chromatic discrimination.

The maximum exposure and energetic quantity during the day is between 11 and 13, in summer when the sun is at the maximum height in the sky. One needs to remember, however, the law of Snellen: the higher the incidence angle, the greater the loss of reflection, therefore it is true that the sun is most efficient when high in the sky but it forms also the maximum angle with the eye axis.

Things complicate when using the eye on reflecting surfaces (snow, water, clear sand) or when one lies down in the sun: in all these cases the angle with the rays becomes very small and their efficiency increase enormously and become more dangerous.

RelatedArticles: Lenses that cut the “Blue”, part 2/4

by Prof. Sergio Villani

The action of the ocular muscles

Saturday, June 2nd, 2007

The external muscles (estrinsecs) with which we move the eye are 6, 4 straight and 2 oblique. With the combined action of these muscles the eye can, within limits, rotate and move in all directions (figure 1).

Muscle action

The figure shows move the eye in the various directions of view

OID = Oblique down right.

RTD = Straight up right.

OSD = Oblique up right.

RSD = Straight up right.

RND = Straight nasal right.

The same acronyms are repeated for the left eye.

From: Optometria e Oftalmologia by Sergio Villani.