Blindness and low vision

Visual acuity is the parameter by which blindness or low vision in a patient is determined.

Blind and visually impaired

According to the definitions of theWHO (World Health Organisation):

- a person is blind when the corrected visual acuity in the better eye is less than 1/20
- a person is visually impaired when the corrected visual acuity in the better eye is between 3/10 and 1/20.
Within this distinction, five categories have been defined (International Classification of Diseases - 9^th revision).

The first and second concern thevisually impaired:
1^a cat. = visus 3/10-1/10
2^a cat. = visus 1/10-1/20
The other three categories concern the blind subject:
3^a cat. = visus 1/20-1/100
4^a cat. = visus 1/100-P.L. (For Far)
5^a cat. = visus off.

In Italy the legal concept of blindness-hypovision was redefined with the Law No. 138 of 2001, 'Classification and quantification of visual impairments and standards for eye tests'. This law introduced the important innovation of considering, for the assessment of damage, not only the state of the central visionbut also the state of peripheral vision (the field of vision).

The previous law (No 382/70), on the other hand, quantified visual impairment on the basis of a single parameter: visual acuity. Thus, it happened that a patient suffering from retinitis pigmentosa or advanced glaucoma, with a visual field reduced to less than 5-10 degrees, was not even recognised as visually impaired.

Blindness and Low Vision in the World

Based on the latest WHO data (2010):

– It is estimated that there are a total of 285 million people with visual impairmentof which 40 million blind e 245 million visually impaired.
- In the developing countriesDue to the strong population increase, the problem is more serious: it is estimated that there are 90% of the total dethe blind andd visually impaired.
- The main causes of visual impairment are: the uncorrected refractive defects (43%) and the cataract (33%).
- The first cause of blindness is the cataract (51%), followed by glaucoma and AMD.
- L'80% of cases of blindness and low vision are due to causes that can be prevented, they are therefore avoidable blindness.
- The number of people with visual impairment due to infectious diseases has been significantly reduced over the last 20 years.

Blindness and low vision in Italy

Based on the 2012 INPS datapublished by the Ministry of Health, the total number of blind people in our country is 129.127distributed by region according to the following table

Resident population: 2012 ISTAT DATA
* pursuant to L.191 art. 2 paras. 106/126

According to 2005 ISTAT estimates the number of visually impaired people in Italy is around one and a half million and is growing steadily. This phenomenon can be explained, first of all, in relation to theageing of the population. Indeed, falling mortality rates, falling birth rates and the concomitant increase in average life expectancy have led to an increase in the number of elderly people.

All major epidemiological studies (National Health and Nutrition Survey; Framinghan Eye Study; Baltimore Eye Survey; Beaver Dam Eye Survey) show that the progress of theage certainly constitutes the risk factor most important for the onset of low vision.

The prevalence of permanent visual impairment, in fact, increases with age, but the increases become exponential after the age of 60: the risk of becoming blind increases by as much as twenty times from the age of 65 to 90! In practice, in individuals aged between 65 and 74 there is a prevalence of 0.4-0.8%, in those aged 75 and over, 2.3% and more.

In addition, progress in ophthalmology, both in terms of prevention and the effectiveness of treatments, has meant that many serious eye diseases, which in the past led to absolute blindness, are now locked into the state of low vision.
Low vision therefore constitutes asocial emergency increasingly important, as the visually impaired individual is unable to carry out normal activities independently related to social and working life.

In addition, a very high level of visual performance is required today at all ages to be able to continue driving cars, working on computers, using tablets, mobile phones and other technological devices.

It should be noted that the 85% of subjects over 65 years of age, with visual acuity less than or equal to 6/18, cannot read standard print characters "effectively" (they read less than 80 words per minute). The 87% of subjects with a visual acuity of less than 6/30 complain of serious difficulties in recognising faces.

With a visual acuity of less than 6/60, 50% of the subjects complain of difficulties in movement and 66% experience difficulties in performing simple tasks, such as dialling a telephone number or using a key correctly.

It is, therefore, of paramount importance that health authorities and governing bodies, both nationally and internationally, commit themselves to preventing the visual loss avoidable in order to guarantee to as many individuals as possible a level of visual functionality that maintains personal autonomy and the possibility of continuing to carry out one's work and social life.

Worldwide, the fight against Avoidable blindness constitutes the objective of Vision 2020 - The right to sight, the joint programme promoted by WHO and IAPB (International Agency for the Prevention of Blindness) to which a large number of NGOs, professional associations, institutions and companies involved in eye-care have joined.

Dr. Carmelo Chines
Direttore responsabile