The significance of vision to health and quality of life cannot be overstated. Of all the different human senses, vision is frequently the most valued. A UK-based study found participants would likely trade-off 10 years of life without sight for 4.6 years in perfect health, while in another US-based nationwide poll, sight loss was deemed worse than life-changing diagnoses such as Alzheimer’s disease, cancer and AIDS/HIV.
From the latest prevalence figures for 2020, annual global productivity loss from vision impairment should approximately be around USD 410·7 billion purchasing power parity. Vision impairment reduces mobility, affects mental well-being, exacerbates the risk of dementia, increases the likelihood of falls and road traffic crashes, increases the need for social care, and ultimately leads to higher mortality rates.
Cataracts, uncorrected refractive error, glaucoma, age-related macular degeneration, and diabetic retinopathy are responsible for most global vision impairment.
New Path to Improve Vision
Vision is limited by two main factors; image capturing and image processing. The eyecare industry focuses almost solely on bending lights and correcting the anatomy of the eyes to achieve optimal image capturing. However, the brain plays a key role in our vision and could be addressed in attempt to achieve optimal vision.
The capability to improve vision by practicing certain visual tasks has been the focus of intense investigation for over the last 40 years. The human ability to see relies on not just a well-functioning eye with good optics, but also on how the brain uses this information . Many examples of poor or low vision cases, such as those due to strokes, traumatic brain damage, or developmental disorders such as amblyopia, make clear that impaired brain processing is an important component of vision. Thus, the ‘training the brain’ approach can potentially lessen the impacts of various eye pathologies, such as retinal and corneal diseases, and can potentially improve conditions of cortical dysfunction such as amblyopia to unlock substantial gains for better functioning individuals across the lifespan.
The visual cortex plasticity decreases with age, with seven years old considered the upper critical age. However, evidence of neural plasticity - visual acuity improvement in adults with amblyopia has been reported after prolonged patching or when the better eye’s vision has been lost or degraded, by age related macular degeneration, cataract or trauma.
Although the visual system's plasticity has been demonstrated with the longevity of benefits, one would assume wide-scale adoption of perceptual learning approaches in clinical settings. However, perceptual learning research has shown limited penetration into the clinic despite the plethora of research. One likely reason could be that most research on perceptual learning is from Psychology and Neuroscience, having limited interactions with Optometrists and Ophthalmologists.
Perceptual Learning, Practical Improvements
So far, numerous studies with perceptual learning have shown to be effective in improving vision, among other dysfunctions:-
· Visual functions in adults with amblyopia
· Uncorrected vision in mild refractive errors
· Central or peripheral vision loss and cortical blindness
· Stroke
· Late-life recovery of visual function
· Dyslexia, and
· It has even been shown to improve the efficacy of other sensory modalities so that they can somehow replace vision (so-called sensory substitution) in blind people.
For the last 20 years, perceptual-learning vision-training technology using Gabor patches has already been shown to specifically promote neuronal lateral interactions, using a set of patient-specific stimuli that improves neuronal efficiency and induce improvement of Contrast Sensitivity Function (CSF) due to a reduction of noise and increase in signal strength.
Cortical stimulation using perceptual learning software program
RevitalVision is a perceptual learning software program scientifically and clinically proven to improve the brain’s visual processing, It is a patient-specific, interactive computerised program based on visual stimulation. The software uses Gabor patches to facilitate cortical neural connections. The patient is initially exposed to a set of visual perception tasks to analyse neural efficiencies or deficiencies, and then collinearly oriented flanking Gabor Patches are displayed in addition to the target Gabor image. This unique lateral masking technique facilitates lateral interaction among neurons and induces high neuronal response. A computerised evaluation using a staircase approach is applied until the patient reaches their visual threshold level. Based on the analysis, a patient-specific treatment plan is created.
More than 25 clinical studies have tested the efficacy of this software program in a variety of eye disease and visual like – Adult Amblyopia, Low Myopia and Presbyopia, Congenital Nystagmus & Strargardt, , Keratoconus and Post Lasik & Cataract surgery by various clinicians across different countries (USA, Europe, and Asia), all showing similar positive outcomes. Studies have been published in peer-reviewed medical journals, with 7 of them being randomised controlled studies.
The studies provide substantial promise for improving visual function in people with poor vision, which can't be further improved by existing vision treatments which focuses on the eyes. Thus, perceptual learning-based training has a positive impact, and the potential impact on society can be substantial.
The author is Paediatric, Squint and Neuro Ophthalmologist, Laxmi Eye Hospital and Institute
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