Guidelines for the visual rehabilitation of the visually impaired.
The guidelines for visual rehabilitation prepared by the Low Vision Academy are a set of systematically developed recommendations, based on continuously updated and official information, put together so that any rehabilitative treatment for the visually impaired is appropriate and of a high standard.
They are a starting point for aligning behaviour and modus operandi within different organisations (both private and public) in the ophthalmology and rehabilitation field. The majority are not mandatory procedures and are therefore called protocols, codes or procedures.
Therefore the choice of certain diagnostic, instrumental, clinical, rehabilitative and organisational procedures are only recommendations.
Eventual variations to these guidelines due to the logistics of each rehabilitation clinic are considered acceptable as long as the rehabilitation objectives have been met.
This document refers to:
• Professionals involved
• Methodology used
This page does not deal with procedures other than those involving patients with visual impairment.
- – ophthalmologist
- – optician / optometrist
– ophthalmic surgeon
– Residual vision measurements
– Standard of life measurements
These diagnostic tests can be carried out in other centres if the ophthalmic rehabilitation clinic doesn’t have the equipment.
– Visual acuity at a distance
– Visual acuity when reading
– Evaluation of contrast sensitivity and / or chromatic sense
– Perimetry full-field testing, manual or computerised (Goldmann, Octopus, Humphrey, etc.)
– Central visual field measurement (Microperimetry MAIA, MP1)
– Fixation assessment (Microperimetry MAIA, MP1)
– Virtual analysis (VirtualIPO©) in order to plan the rehabilitation procedure by determining:
– required magnification and decentralisation of text
– suitable system based on the minimum magnification necessary and maximum given field
– number of letters in the reading field
– light intensity suitable for the best contrast
– PhotoReceptor Layer (PRL) and Preferential Reading Field (PRF) ratio and the consequent rehabilitation prognosis
– decentralisation of the fixation target according to the reading line used for the construction of targeted exercises (2 minutes per eye).
These diagnostic tests should always be carried out in the ophthalmic rehabilitation clinic with the exception of virtual analysis that can be performed online.
Using assessment tests designed to verify the patients standard of life in relation with his / her visual impairment and monitoring any changes after visual rehabilitation.
– Limoli-Vingolo Test
– ADVS – Activities of Daily Vision Scale
– Satisfaction Profile
– General Self-Efficacy Scale
Mainly on the basis of medical records.
– Working at a computer
The present study aims at establishing a customised rehabilitation process depending on the type of low vision involved, even though many general aspects are common to all types of rehabilitation.
Schematically, we can define the following rehabilitation categories:
– Patients with low central vision and absolute scotoma (eccentric fixation)
– Patients with low central vision and relative scotoma (central fixation)
– Patients with low peripheral vision (tubular visual field)
– Patients with low vision due to blind spots (quadrantanopia or hemianopia)
– Patients with low vision due to nystagmus
– Patients with prognoses ranging within these definitions
Rehabilitation consists of teaching a patient to use their residual vision.
This is done in two ways:
Using optical aids that magnify or modify the image in order to improve perception
Using visual training to improve fixation quality and to restore the performance of the receptive fields.
Prior to visual rehabilitation, the patient must try out the best aids indicated for their particular visual impairment.
Finding the ideal optical aid can be obtained by empirical evidence, or virtual analysis that also provides other useful information for rehabilitation (see above under the heading: Residual vision measurement).
Patient with low visual acuity: magnifying aids (optical, electronic, computerised) suitable to solving the inherent problems (reading, manual activities, watching TV, domestic autonomy, general mobility…)
Patient with low contrast sensitivity: aids that improve the contrast of images (filters, electronic or computerised systems) and/or lighting solutions.
Patient with glare problems or poor recovery after photostress: aids that improve the image contrast and reduce glare (filters, electronic or computerised systems) and/or lighting solutions.
Patient with peripheral visual field contraction: aids that reduce the image size (reverse telescopes, prisms). These patients can be directed to orientation and mobility courses.
Once the correct aid has been found the patient is taught how to use the areas of residual vision through the proper use of the equipment. To this end, a series of appointments are organised with the orthoptist to address the primary problems reported in the patient’s preliminary visit: the patient carries out various tests (reading, writing, walking, etc.).
Simple aids, used instinctively, require very little training which is often limited to a few simple explanations followed by immediate use.
Complex aids require more demanding training where the patient has to practice using the specified aid during certain activities. In some cases it is opportune not to go on to the next stage until the appropriate training has proven the solution to be efficient.
The tests used must use fixation targets which ensure projection of the reading line is in the residual vision area.
Evaluation of rehabilitation training is done by recording data before and after the rehabilitation cycle.
Reading speed (VL), calculated on short texts of about 2-5 minutes, measured in words per minute (WPM).
Short-term Comprehension and Retention (C-RBT) based on questions to check understanding and memory of what has just been read, expressed as a percentage (%).
Reading coefficient (CL = VL x C-RBT/100). If the C-RBT is 100% CL is the same as VL. The CL is an absolute value.
The number of required sessions can go from 2 to 6-7 depending on the severity of the impairment, the adaptability and learning ability of the patient, their motivation, and whether or not other diseases are present.
Visual Training is a set of methods aimed at optimising residual vision, or improving fixation quality and stability (sound healing biofeedback), or visual field sensitivity (photo stimulation).
Sound healing biofeedback: patients with eccentric or unstable fixation can undergo a series of exercises to improve fixation quality. These exercises use biofeedback mechanisms that teach the patient to recognise the target on hearing the right acoustic tone. Continuous repetition of the exercise trains the patient to fix on an object in a more stable way.
The most commonly used devices are:
Photostimulation: various devices which are capable of activating the residual receptive fields of the retina (light stimulation, optical patterns) in order to reactivate the actual lines of vision.
The equipment or methods most commonly used are:
In general, the visual training sessions are numerous (at least 10 in the first cycle) and cycles have to be repeated two or three times a year but with less sessions (usually 5-session cycles).
Some procedures, such as Revital Vision, require more sessions (between 40-60), although there is the advantage that they can be carried out at home.
This is any form of surgery aimed at improving the visual quality of the ocular dioptres.
– Phacoemulsification where cataracts are present
– Phacoemulsification with refractive defects
– Refractive surgery with refractive defects alone or associated with nystagmus
Hyperopia and astigmatism, especially at a medium-high level, are always counterproductive in any rehabilitation process, due to an increase in spherical and astigmatic aberrations.
Myopia, if moderate, can increase the magnifying effect of an aid.
They aim to contain the degenerative process causing low vision, in order to stabilise the underlying disease. Sometimes they can also achieve a significant increase in sight.
– Treatment using antioxidants
– Treatment using neurotrophic substances
– Treatment using anti-VEGF
– Grafts using autologous cells or tissues and / or autologous or heterologous stem cells
– Grafting devices for continuous growth factor secretion
Study of the timing for clinical, diagnostic and therapeutic monitoring necessary to prevent any deterioration in residual vision.
Any changes in visual functions and close vision requiring further appropriate rehabilitative treatment.