Low vision: what is it and when to take action?

By Cristiano Antonino On May 25, 2023

Low vision refers to a condition of very limited visual capacity, a tremendously disabling condition for sufferers. Those affected by low vision are generally the elderly between the ages of 65 and 84

If not treated effectively, low vision could degenerate into permanent partial or even total blindness.

Low vision – along with functional blindness, legal blindness and blindness – is one of those diseases considered to be ‘visual impairment’ and can therefore be classified as severe (with visual residue of no more than 1/10 in both eyes or in the better eye even with correction – binocular perimetric residue of less than 30%) medium-severe (with visual residue of no more than 2/10 in both eyes or in the better eye even with correction – binocular perimetric residue of less than 50%), mild (visual residue of no more than 3/10 in both eyes or in the better eye even with correction – binocular perimetric residue of less than 60%).

What are the causes and risk factors of low vision?

Low vision can be caused by a wide variety of factors.

This condition, which, as we have seen, generally affects elderly patients, sees ageing as its main risk factor: with increasing age, one is biologically predisposed to incurring diseases that damage (especially) the retina, which drastically reduce visual acuity.

Therefore, generally speaking, low vision as a ‘condition and not a pathology’ is never an end in itself, it is always found as a secondary effect or related to pathologies that, in themselves, drastically reduce the quantity and quality of vision:

Diabetes: a systemic disease characterised by high blood sugar which, if left untreated, can lead to reduced central vision.

Albinism: genetic condition caused by the absence of melanocytes that can lead to reduced central vision.

Glaucoma: eye disease usually caused by high eye pressure that eventually damages the optic nerve. In advanced stages it can create serious problems of visual impairment.

Retinitis pigmentosa: genetic disease that causes atrophy of the retinal receptors.

Corneal abnormalities: cataracts, keratoconus, etc.

Age-related or juvenile macular degeneration: disease affecting the centre of the retina, causing the progressive death of the cells that make it up. If underestimated it leads to a serious decrease in vision, to the point of preventing the performance of basic daily activities.

Ageing and senescence of ocular structures.

Low vision: how to recognise the symptoms

The main symptoms that a visually impaired person will experience during the progression of his or her condition are a decrease in visual acuity, which will spill over into daily life with blurred vision and consequent difficulty recognising things or people, difficulty or inability to read, inability to watch television, driving problems or total inability to drive a moving vehicle.

The condition of low vision leads to severe psychological distress for the sufferer due to the inability to perform a whole series of normal everyday actions (even mundane ones) that were previously taken for granted.

Diagnosing low vision

The specialist in charge of treating low vision is the ophthalmologist, who will test the patient for near and far visual acuity, refractive error, contrast sensitivity, reading speed, visual field width, colour vision and sensitivity to sudden glare.

Low vision: the most appropriate therapy

In the event that the previous tests the ophthalmologist has subjected the patient to have led the specialist to a diagnosis of low vision, the patient must be informed of the slight possibility of even partial recovery of their original visual capacity.

The corrective methods proposed by the ophthalmologist will essentially depend on two main criteria: if the patient has reduced visual acuity, aids – optical or non-optical – will be used for image magnification; if the patient has a reduction in the visual field, optical aids will be used for an apparent enlargement of the angle.

Reduction in visual acuity

When the patient presents with an appreciable reduction in visual acuity, optical aids capable of enlarging images, such as positive lenses, will generally be used.

Visual field reduction

When, on the other hand, the patient presents with an appreciable reduction in the visual field, optical instruments capable of enlarging it should be given to him, bearing in mind that, in general, such instruments tend to reduce visual acuity jointly.

Among the instruments to be considered are the inverted telescope, prisms, total reflection or semi-transparent mirrors and anamorphic lenses.

Low vision: visual rehabilitation

In Italy, until not many years ago, there was no culture of visual rehabilitation.

This culture was a necessary development after the WHO – in 2010 – publicly declared the continuous and progressive growth of low vision cases not only in our country, but worldwide, reaching more than 246 million cases globally.

This declaration has forced the health systems of all countries to take a real leap of faith: not only is prophylaxis and therapy required, but also and above all the rehabilitation of the visually impaired person.

A person who has developed a condition of low vision finds himself catapulted into a world that does not belong to him, full of difficulties and dangers that he did not have to consider before; a world in which even the simplest everyday actions now appear impossible to perform.

For this reason, visual rehabilitation must act as a complement to vision therapy, so as to support – also psychologically – the visually impaired patient, helping him or her with customised methods to adapt and orientate themselves in the world as a visually impaired person.

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