Archive for the ‘Optometry’ Category

« Older Entries

Contact Lenses Power

Sunday, September 5th, 2010

Contact Lenses PowerQUESTION

I’ve been told that to calculate the right power of one’s contact lenses we must detract 0,25 diopters to the real one; mine is 1,50 and 2,00, should I choose 1,25 and 1,75 ? Other people told me that this detraction must be considered only when the graduation exceeds 3 diopters.

ANSWER

There is a mathematical formula that correlates the power of contact lenses with that of the lenses of prescription glasses. Such formula is mathematically affected by 2 factors:

  • the power of the lens on the glasses
  • the distance of the glasses lens from the corneal apex (eye)

This formula suggests that if the power of the lens doesn’t exceed 5,00 diopters, no significant variation occurs on the power of contact lenses.

Therefore, if your powers are 1,50 and 2,00, you can put contact lenses of the same powers; in case the power reduction makes your vision more comfortable, it is probable that the measurement of your graduation was not correct.

Posted in Eyesight flaws, Optometry, Prescription Lenses | No Comments »

Dry Eyes

Wednesday, August 25th, 2010

Dry EyesQUESTION

After wearing my contact lenses for a while, I have got the feeling that my eyes are becoming dry.

ANSWER

When one senses the unpleasant feeling of “dry eyes”, which leads to reduce the time lenses are worn and to increase the frequency of blinking (eyelid winking), we can reasonably think about different problems:

- real “ocular dryness” (or, as to say, insufficient tears). In order to correctly evaluate this problem, it is necessary a serious medical examination;

- the internal geometry of the lens (inner shape) is not suitable to the patient’s ocular situation. In this case, a visit to the authorized optician of the contact lenses is needed;

- the lens “interefe” with the natural mechanism that controls and stimulates the frequency of the blinking (eyelid winking) and the patient must be “taught” how to restore the normal frequency of the blinking. To this aim, specific exercises exist which the optician must adjust to each single patient.

Posted in Optometry, Prescription Lenses, Protect your eyes | No Comments »

How Can I solve Photophobia?

Monday, August 16th, 2010

Photophobia

QUESTION

Many people ask me how to solve photophobia, among them a photophobic girl who recently asked me how to cure it.

She suffered from headache, especially when she couldn’t wear sunglasses.

“I’ve been photophobic from a while. I usually wear dark sunglasses -those which protect from UV rays- but when I can’t use them -in the classroom, for example-, I can’t bear the light and I am not able to concentrate myself. What should I do? Can I recover from photophobia?”

ANSWER

Photophobia is not in itself a phatology, but just a symptom of another situation happening at that moment. I strongly advise you to go to your Oculist and show him your state.

As far as glasses are concerned, I assure you that there are no glasses that can cure photophobia; sunglasses (even though very dark) may help soften the effects of photophobia.

To sum up: you don’t have to find a treatment for photphobia, but for the problem that causes it.

Posted in Optometry, Suggestions | No Comments »

Contact Lenses Firmness

Thursday, August 5th, 2010

Contact Lenses FirmnessQUESTION

Sometimes it happens that we experience “firmness” problems with contact lenses.

In fact, the lens (either hard or soft) may “shift” from its regular position with eye-winking. Everybody asks the reason why such thing happens, but the answers are really simple.

ANSWERS

1. The lens has not been constructed with the right parameters (this is a manufacturing defect);

2. The lens has been correctly constructed, but it does not fit the eye shape (this is an “adaptation” mistake, so a technical mistake by the Optician).

There are no further reasons that may cause a problem related to the unwanted “shifting” of the lens within the eye.

Posted in Optometry, Prescription Lenses, Suggestions | No Comments »

Different-Coloured Eyes

Friday, July 16th, 2010

Different-coloured Eyes

QUESTION

A young girl realised she has two different coloured eyes, one is blue and one is greenish! Her oculist told her the phenomenon was due to “stained” lens.  The girl enquires about her situation and how she could solve it.

ANSWER

If her annotation refers to iris coloration, it is an ordinary phenomenon (which is called ANISOCORIA). On the contrary, if the diversity of coloration refers to pupils, it is possible that her oculist was right.

To banish all doubts, we advise the patient to visit another expert.

Posted in Optometry, Suggestions | No Comments »

Preliminary Tests For Contact Lenses

Tuesday, July 6th, 2010

Test for contact lensesQUESTION

Why my contact lenses annoy me after only 3 hours?

ANSWER

Many problems which come up while wearing contact lenses stem from poor preliminary tests. And this is also why a Patient may experience annoyance after just 3 hours of wearing contact lenses. In fact, the purpose of these preliminary tests is to find out the best technical solution.
It is true that a period of “physiological adaptation” is necessary, but it is also true that such period (at least for soft lenses) should be more or less a week. Once this period is over (unless there are evident improvements), it is good that the Optician checks the whole technical aspect of the adaptation.

Posted in Optometry, Prescription Lenses, Protect your eyes | No Comments »

Accommodation of Contact Lenses

Tuesday, June 1st, 2010

Accommodation of contact lensesQUESTION

We are frequently asked about the correct use and accommodation of contact lenses.

ANSWER

Here below are the legal and technical procedures to follow:

1. medical check-up, which is necessary to evaluate whether the patient is suitable to the use of contact lenses;

2. technical control (on behalf of the Optician), to decide which kind of lenses to choose;

3. technical assistance to the patient to teach him how to use and maintain his own contact lenses;

4. follows-up to make sure that the use of contact lenses is not causing damages or problems to the eyes.

This is the procedue highly recommended by all professional associations of both oculists and opticians. Sometimes, to shorten times, one or two steps are skipped and that is when problems come up which are “erroneously” attributed to contact lenses.

Posted in Optometry, Prescription Lenses, Protect your eyes | No Comments »

What is the use of over-readers?

Sunday, May 2nd, 2010

Over readersQUESTION

We ofter hear about “Over-readers”, and many people wonder what their use is.

ANSWER

We are in presence of a visual defect, which must be compensated for.

Usually, those who mostly need over-readers are long-sighted and astigmatic people. They are visual problems that, once corrected, will cause a sense of “relaxation”, but as a secondary effect of the solution of another problem.

Posted in Accounting, Optometry | No Comments »

Many Dangers to the Eyes 2-2

Monday, December 14th, 2009

For many years, prevention has been the main focus of lenses and frames manufacturers, but today new alarms are drawing ophthalmologists’ attention, in particular with reference to sunbeds, coffee and cigarettes. According to Francesco Loperfido, responsible for the General Ophthalmology Center at the San Raffaele hospital in Milan, “a long exposure to sunbeds’ rays may cause harm to both skin and the eyes”. The injuries which can be caused to the eyes by a long exposure include keraconjunctivitis and, in the most sever cases, the opacity of the crystalline lens. Besides, SOI experts reminded that smoke may put sight at risk and the disease is called alcoholic neuritis -as Antonio Mocellin, SOI vice-president, explained. Alcohol and smoke, but also too much caffeine, may cause an ocular intoxication. Caffeine and nicotine, in fact, restrict the veins and, in the end, produce damages to the optic nerve; as a consequence, eyesight is reduced and a visual field deficit appears which, if neglected, can lead to very severe injuries. In addition to the usual "enemies", new factors must now be taken into account, due to the many and continuous changes in lifestyle. Those who work outdoor, for example, are more exposed to this kind of risks: masons, refuse-collectors, fishers, or even postmen. A market section could develop within the optic field, similar to those already present in other product categories, like clothing, shoes, gloves, etc. In conclusion, many are the dangers to which the eyes are exposed. It is the experts’ duty to inform and help to prevent the patient’s eyes from severe damages.

Tratto da B2eyesmagazine maggio 2008

Posted in Eyesight flaws, Optometry, Protect your eyes | No Comments »

Many Dangers to the Eyes 1-2

Wednesday, December 9th, 2009

Although UV rays are known as the “long-term enemy” of the sight, today more and more attention is focused on blue light, particularly harmful to minors and people over the age of 55. A study from Cnr Biometereology Institute, carried out by the Sight Defense Commission and shown in Milan, revealed blue light’s dangerousness: its wave length, indeed, falls within the visible range, but near UV (400-500mm). In this case, the damage is not direct: the eye is very rich in oxygen and all the parts that make it up are sensitive to oxydative stress and, if hit by light, produce several free radicals that, over the years, cause a progressive damage. To protect one’s eyes from ultraviolet rays and blue light since childhood is pivotal. Unfortunately, still today many parents underestimate the problem and buy low-quality products. Instead, the purchase of a good product is the starting point of a correct prevention in general, both for children and for adults. The optician will be glad to help anyone, irrespective of age, to find the most suitable frame.

Found in B2eyesmagazine, May 2008

Posted in Eyesight flaws, Optometry, Protect your eyes | No Comments »

« Older Entries