Jump to content

Vision Considerations in Function Based Rehabilitation

Original Editor - Ewa Jaraczewska based on the course by Eric Hammer

Top Contributors - Ewa Jaraczewska, Jess Bell and Tarina van der Stockt  

Introduction

Vision impairment is a significant global health challenge, affecting an estimated 2.2 billion individuals worldwide.[1] For at least one billion people, their vision impairment is either preventable or has not yet been addressed.[1] For many people with vision impairments, there is a potential for impactful interventions.[2] However, addressing the challenges of low vision requires a multi-level and multidisciplinary approach with enhanced public awareness, improved screening, increased availability of eye care specialists and access to affordable rehabilitation.

This article discusses the basic anatomy and physiology of vision, the impact of low vision and vision loss, the role of the multidisciplinary team in vision rehabilitation, visual screening, rehabilitation interventions, and home, work, and school adaptations for people with vision impairment.

Anatomy

How the eye works

The eye detects light and sends visual signals to the brain. Key components of the eye are the cornea, the outer layer that bends light; the iris, which is responsible for controlling the amount of light entering the eye; the lens, which can change shape to focus light on the retina; the retina, which contains specialised photoreceptor cells; the macula, which is responsible for central vision and fine detail; and the optic nerve, which transmits visual signals from the eye to the brain. The optic nerve contains over a million nerve fibres, each carrying information from a specific retinal region.[3]

Physiology

The transmission of visual signals to the brain involves four steps: [4]

Step 1: Photoreceptor cells in the retina absorb light

Step 2: The absorbed light is converted into electrical signals

Step 3: The electrical signals are sent to the optic nerve

Step 4: The optic nerve transmits visual (light intensity, colour, and spatial location) and non-visual (the timing and duration of visual stimuli) information to the brain, where they are processed and interpreted.

The brain processes visual information hierarchically. First, it processes basic features like line orientation and colour, next it integrates this information to create more complex representations of the visual world.

The Impact of Vision Loss on Daily Life

Partial or complete vision loss can significantly impact an individual's daily life, affecting essential activities, such as reading, driving, and mobility, as well as instrumental activities of daily living, like shopping, meal preparation, and cooking. Visual impairment is also linked to a higher risk of accidents, falls, and functional limitations. Research indicates that quality of life decreases as the severity of visual impairment increases, suggesting that lower levels of functioning correspond to a lower quality of life in individuals with visual impairment.[5]

The impact of vision loss can be particularly profound for younger individuals. Working-age people with visual impairment often report a lower quality of life compared to their peers without visual impairment.

Individuals with visual impairment may face loneliness and unemployment. They may experience bullying and physical or sexual assault. These experiences have been connected to an increased risk of mental health conditions, including depression and post-traumatic stress disorder.[5]

"Self-efficacy refers to a person’s belief in his or her ability to successfully perform a task or influence an event to a desired outcome."[6]

Research on some metrics for people with visual impairments is conflicting. According to Brunes et al.,[6] people with visual impairment may show higher self-efficacy and a general belief in their ability to cope with challenges. This high self-efficacy could come from extensive experience navigating life with reduced vision and is a positive force for achieving a fulfilling life.[6] However, other studies indicate that visual impairment can negatively impact self-esteem for people performing daily activities. This reduced self-esteem may hinder their ability to advocate for themselves.[7]

Classification of Visual Impairments

"(..) a vision impairment results when an eye condition affects the visual system and one or more of its vision functions." World Health Organization[1]

Visual acuity is a measure of a person's ability to distinguish shapes and the details of objects at a given distance, usually 6 metres (or 20 feet) compared to a person with normal vision.[8][1] It is usually measured using the Snellen chart, where normal vision is recorded as 6/6 (or 20/20). For example, a person with a visual acuity of 6/18 (or 20/60) can read at 6 metres what a person with normal vision can read at 18 metres.[1] A visual field "is that portion of space in which objects are visible at the same moment during steady fixation of gaze in one direction." [9] The horizontal visual field typically spans around 180 degrees. The vertical visual field is restricted by the structure of the face to around 50 degrees upward and 70 degrees downward.[10]

According to the World Health Organization, there are six classifications of visual impairment based on visual acuity in the better eye:[11]

  • mild vision loss, or near-normal vision, with 20/30 to 20/60 (or 6/12 to 6/18) vision in the better eye
  • moderate visual impairment, or moderate low vision, with 20/70 to 20/160 (or 6/18 to 6/60) vision in the better eye
  • severe visual impairment, or severe low vision, with 20/200 or worse (or approximately 6/60) vision in the better eye, and/or visual field is 20 degrees or less
  • profound visual impairment or profound low vision, with 20/500 to 20/1000 (or 6/150 to 6/300) vision in the better eye, and/or visual field is 10 degrees or less
  • near-total visual impairment or near-total low vision, with less than 20/1000 (or less than 6/300) vision in the better eye, and/or visual field is 5 degrees or less[12]
  • total blindness or total visual impairment, with no light perception in the better eye

Note: If visual acuity is too poor to be measured with a Snellen chart, it can be estimated by asking the patient to count the number of fingers held up approximately 1 metre away.

The Snellen chart to assess visual acuity
Normal and limited field of vision

Vision Impairment in Common Eye Pathologies

Cataracts, uncorrected refractive errors (which are easily treatable with glasses, contact lenses, or refractive surgery), age-related macular degeneration, glaucoma, and diabetic retinopathy were identified as the primary causes of blindness in individuals aged 50 and above in 2020.[13]

Cataracts

Cataracts remain the leading cause of blindness and the second leading cause of moderate and severe vision impairment.[14] Cataracts can cause a range of visual impairments and symptoms,[2] including a decline in visual acuity. This change in visual acuity leads to progressive difficulty with tasks that require sharp vision, such as reading fine print, driving, especially in low light conditions, or distinguishing facial features.

Cataracts can also cause increased sensitivity to light and glare (photophobia). This is often exacerbated at night, making night driving dangerous. Similarly, bright sunlight can be overwhelming, causing people with cataracts to squint frequently or seek shaded areas.

They can alter a person's perception of colours—colours that once appeared vibrant and distinct may begin to seem faded, dull, or even take on a yellowish or brownish tint. The overall clarity of vision is profoundly diminished, leading to a hazy or cloudy appearance, as if looking through a dirty window.

Cataracts can also cause monocular diplopia, or double vision in one eye, where an object appears as two distinct images when looking with only the affected eye, and a "halo effect" around lights, particularly at night, where a ring of light surrounds bright sources.

Macular degeneration

According to the World Health Organization, 196 million people worldwide have vision impairment due to age-related macular degeneration.[15]

Age-related macular degeneration (AMD) is a progressive degenerative eye disease that causes a gradual deterioration of the macula. It causes blurred central vision, where objects directly in front of the eye appear indistinct, distorted vision (metamorphopsia), where straight lines appear wavy or bent, and potentially a central blind spot (or scotoma). This blind spot makes it difficult or impossible for a person to see what is directly in front of them. As the condition progresses, it can cause dark or blank spots at the centre of a person's field of vision. This affects a person's ability to perform everyday activities that require detailed central vision, such as reading fine print, driving, and recognising faces.[16]

Glaucoma

Globally, 76 million people are affected by glaucoma.[1][17] Traditionally, glaucoma has been linked with a loss of peripheral vision, creating "tunnel" vision.[18] However, it can also cause diminished vision quality. As a result, people with glaucoma may need more light to perform a task. Contrast sensitivity and colour discrimination can deteriorate early in the disease and people with glaucoma often complain of vision issues, such as blurriness, dimness or cloudiness.[18]

Diabetic Retinopathy

Diabetic retinopathy affects 146 million people worldwide.[1] It is a debilitating complication of diabetes mellitus, leading to irreversible blindness among individuals in their working-age years. Diabetic retinopathy is a microvascular disease, characterised by progressive damage to the delicate capillary network of the retina. This damage, in turn, leads to significant visual impairment, such as multiple blind spots (scotoma) and poor visual acuity.[19][3]

Vision Rehabilitation

This section focuses on rehabilitation interventions for the four main types of visual impairments: moderate, severe, profound, and total blindness.

Vision rehabilitation aims to help people with significant vision loss or blindness to regain or develop essential abilities and skills. These vision-dependent skills are crucial for safety, mobility, and independence.

Vision rehabilitation specialists deliver therapy that focuses on sight enhancement and/or sight substitution skills, strategies, and the use of assistive devices. The nature and intensity of post-vision loss rehabilitation are personalised for each person. Key factors determine the overall rehabilitation approach, including the severity of vision loss, co-occurring conditions, psychosocial factors, and personal goals, such as maintaining employment or continuing to live independently at home.[20]

The goals of vision rehabilitation include:[3]

  • optimising the use of any remaining functional vision
  • educating patients on applying assistive technology and devices in daily activities
  • teaching compensatory strategies for everyday tasks
  • facilitating safe mobility within the home and community, including work or school environments

Vision Rehabilitation Specialists

Low-vision specialists, such as ophthalmologists, optometrists, vision rehabilitation therapists, occupational therapists, and orientation and mobility specialists, are specifically trained to assist in vision rehabilitation, from assessment to management and provision of assistive devices. Other rehabilitation specialists, such as physiotherapists, social workers, and speech and language therapists, are also part of the multidisciplinary team dedicated to working with low-vision individuals. Each team member has a unique role in enhancing activities for individuals with vision loss.[3]

Ophthalmologists are medical doctors who diagnose and treat eye conditions. In some countries, there is also a pathway for osteopathic physicians to become ophthalmologists. Ophthalmologists perform diagnostic testing to assess eye health, identify eye pathologies and provide medical and surgical eye care. Ophthalmologists are also trained to prescribe eyeglasses and contact lenses when appropriate.[21]

Optometrists conduct eye examinations and vision tests. They can also prescribe and dispense corrective lenses, identify specific eye abnormalities, and prescribe medications for certain eye conditions.[21]

Vision rehabilitation therapists (VRT) or occupational therapists provide compensatory skills and advice on assistive technology to enable people with vision loss to have safe, productive, and independent lives. They work in various settings,[22] providing support to enhance vocational opportunities, promote independent living, and support the educational development of people with vision loss. They also conduct home assessments and provide recommendations on home modifications.[3]

Orientation and mobility specialists (OMS) work with individuals who are blind, have low vision, or experience functional visual limitations. These professionals can be blind, partially sighted, or sighted themselves. Orientation and mobility specialists address the non-visual, visual, physical, cognitive, and psychosocial aspects of mobility training for individuals of all ages, with diverse needs and abilities. Their methods and strategies include non-visual techniques (auditory and tactile) and visual techniques, such as optimising any reliable remaining vision.[23] For example, they teach different travelling techniques for home, work, and the community.[3]

Physiotherapists provide interventions to help people with vision impairments improve their balance, endurance, strength and walking. These interventions aim to facilitate or enhance a person's participation in daily activities at home, work or school.[3]

Social workers empower people with vision loss to handle future challenges by providing information on eye conditions, related issues and resources for people with vision impairment. They also help establish support groups for people with vision loss and caregiver support groups. These groups can promote peer interactions.[24]

Speech and language therapists focus on developing stomatognathic functions for people with vision impairment (e.g. sucking, chewing, swallowing, speaking) and provide guidance to families. They work with educators on cognition and literacy development and promote the development of communicative skills, language, interaction, and interpersonal relationships for people with vision impairment.[25]

Counsellors or psychologists help individuals with vision impairment cope with their diagnosis, adjust to new lifestyles, and maintain a positive outlook. They provide individual, group, and family counselling, and help people develop coping strategies, promote self-advocacy, and address issues like anxiety, depression, and social isolation.[3]

Occupational Therapy and Vision Screening

Occupational therapists do not diagnose vision disorders, but they can describe symptoms related to visual impairment and how these symptoms affect a person's occupation.

Warren's Hierarchical Model of Visual Processing is "a developmental framework for evaluation and treatment of visual perceptual deficits in adults with acquired brain injury."[26] In this framework, visual function is organised based on various visual components, including visual acuity, contrast, ocular motor control, visual fields, saccades, accommodation, convergence to visual processing, visual cognition, and occupation. These components should be addressed by occupational therapists conducting vision screening and assessment.[26] Please follow this link if you would like to learn more about the occupational therapy approach to assessing and managing vision loss.

Rehabilitation Interventions for Vision Loss

Vision rehabilitation aims to help individuals with vision loss maximise their existing vision, maintain independence and enhance their quality of life. The following sections discuss various strategies and rehabilitation interventions that can be beneficial for people with vision loss.

Gooseneck lamp

Lighting: many people with vision loss will benefit from enhanced lighting. Finding the right lighting solution for each person relies on trial and error, but three common types of lighting—incandescent, halogen, and LED—can be tried. Various tools or devices can be used to direct light to illuminate a specific item or area, including gooseneck lamps (see image), floor or desk lamps with magnification and headlights, which can also be used as portable lights in dim spaces.[3]

Glare: staring directly at a light source, such as sunlight through a window, is difficult for people with low vision. It is better to position the person in front of the light source as this illuminates the environment and improves visibility. There are various glasses available to help control glare, including wraparound glasses that go over prescription glasses and prescription sunglasses with different coloured lenses (e.g., amber or yellow). People with vision loss should consult with an optometrist to determine the optimum coloured lens for them.[3]

Organisation: creating organised spaces can help people with vision impairments more easily locate items. When organising a space, it's crucial to involve the patient as each person will have different preferences and requirements. For example, when organising a wardrobe, one person might choose to organise items by colour or clothing type (e.g., pants, short-sleeved shirts, blouses) while others might prefer to organise their closet by outfits, matching items together. There are a range of tools to help organise wardrobes, including small dividers for clothes racks.[3]

Furniture arrangement: when arranging furniture, prioritise decluttering and creating safe pathways by (1) minimising the presence of low-profile furniture, or by moving them out of main traffic areas, (2) creating clear pathways by ensuring there is enough space between pieces of furniture to allow for easy and safe movement, and (3) returning items to their place after they were moved.[3]

Stairs contrast tape

Contrast: contrast is essential for individuals with low vision, as it enhances visibility and safety in various daily situations. Examples include marking stair edges (see image) and the start of handrails with contrasting colours, using high-contrast text in reading materials (e.g., black on white, white on black, or yellow on black), and contrasting dishes and placemats during dining to help the person locate the plate and food. The key is to choose colour combinations that provide a clear contrast and reduce glare while considering individual preferences.[3]

Labelling and tactile tools: adding labels and tactile cues can help people with vision impairments identify items. For example, large-print index cards and rubber bands (see image of canned goods) can be used to label pantry items. This approach has a dual purpose because when the food item has been consumed, the index card can be placed in a box and used to keep track of items for a grocery list. Similarly, spices can be organised either alphabetically or by using varying numbers of rubber bands. The person with vision loss can use scent and touch to confirm spice selection.[3]

Other tactile tools, such as raised buttons/dots (see image of a washing machine). You can get different sizes that can be placed on kitchen or utility devices to mark frequently used buttons, such as stop/start on a washing machine or dryer, dials on an oven or microwave. An example for use on a microwave is to place the buttons on even numbers for the food heating time and the start button.

Labels for canned goods
Different-shaped tactile buttons


Assistive technology: various assistive technologies are designed to enhance accessibility for individuals with visual impairments, such as customisation options for devices, different magnification tools (handheld, pocket, dome, and telescope glasses), and electronic magnification devices like CCTV/video magnifiers with text-to-speech capabilities. There are also a range of keyboard adaptations, such as large-print keyboards and overlays, smart glasses, audiobooks, and text-to-speech functionalities.[3][27]

CCTV/video magnifier
Magnifying glass
Telescope glasses


Orientation and Mobility Training

Orientation and mobility training teaches individuals with low vision or blindness to navigate their environment safely and independently. This includes:[3]

  • cane travel training, where the person learns to use a white cane to detect obstacles and terrain changes
  • stair training, so a person can safely ascend and descend stairs
  • street crossing training, which includes navigating intersections and crossing streets
  • mass transit navigation, where the person learns to use and navigate public transportation systems
  • familiar route training, which involves practising travel on common routes, such as those to work, school, or home

Before referring patients for orientation and mobility training, it is crucial to assess their cognition, balance and endurance.

Sighted Guide Technique

The sighted guide technique is a method for guiding individuals with low vision. It includes the following steps:

  1. Initiation: the guide gently taps the individual on their arm, shoulder, or elbow to indicate their presence.
  2. Grip: the person with low vision forms a "C-grip" with their hand and holds onto the guide's elbow. For example, if the guide is on the left, the person with low vision uses their left hand to hold the guide's left elbow. The C-grip allows the person with low vision to feel the guide's movements, such as going up stairs or making turns, providing valuable feedback.
  3. Movement: the guide walks forward, and the person with low vision follows. The guide can verbally provide additional cues, such as "We're coming to a door, it swings open to the right," or "We're entering a narrow path."

If the person with low vision has balance issues, the guide can hook their arm under the person's elbow for increased stability.

When interacting with individuals with low vision it is important to remember the following:

  • never grab an individual's arm and pull them—this can be disorienting and frightening
  • always approach them first by gently touching their arm or shoulder
  • clearly state your presence and offer assistance: "I'm here. How can I help you?"

This optional video explains the sighted guide technique to assist a blind person or a person with low vision to travel indoors and outdoors.

[28]

Resources

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 World report on vision. Geneva: World Health Organization; 2019. Available from https://iris.who.int/bitstream/handle/10665/328717/9789241516570-eng.pdf?sequence=18 [last accessed 24.6.2025]
  2. ↑ 2.0 2.1 Canatan AN. Restoring sight: exploring cataracts as the leading treatable cause of blindness: a narrative review. Turk Med Stud J 2024;11(1):1-8
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 Hammer E. Vision Considerations in Function Based Rehabilitation Course. Plus, 2025.
  4. ↑ Sánchez López de Nava A, Somani AN, Salini B. Physiology, Vision. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from https://www.ncbi.nlm.nih.gov/books/NBK538493/ [last accessed 27.6.2025]
  5. ↑ 5.0 5.1 Bonsaksen T, Brunes A, Heir T. Quality of life in people with visual impairment compared with the general population. J Public Health (Berl.) 2025;33:23-31.
  6. ↑ 6.0 6.1 6.2 Brunes A, Hansen MB, Heir T. General self-efficacy in individuals with visual impairment compared with the general population. PLoS One. 2021 Jul 2;16(7):e0254043.
  7. ↑ Sowislo JF, Orth U. Does low self-esteem predict depression and anxiety? A meta-analysis of longitudinal studies. Psychol Bull. 2013 Jan;139(1):213-240.
  8. ↑ Marsden J, Stevens S, Ebri A. How to measure distance visual acuity. Community Eye Health. 2014;27(85):16. PMID: 24966459; PMCID: PMC4069781.
  9. ↑ Spector RH. Visual Fields. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 116. Available from: https://www.ncbi.nlm.nih.gov/books/NBK220/
  10. ↑ What is vision impairment? Available from https://www.visability.com.au/about-visability/vision-resources/what-is-vision-impairment/ [last accessed 25.6.2025]
  11. ↑ American Optometric Association. Low vision and vision rehabilitation. Available from: https://www.aoa.org/healthy-eyes/caring-for-your-eyes/low-vision-and-vision-rehab (accessed 9 July 2025).
  12. ↑ Lee SY, Gurnani B, Mesfin FB. Blindness. [Updated 2024 Feb 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from https://www.ncbi.nlm.nih.gov/books/NBK448182/ [last accessed 25.6.2025]
  13. ↑ GBD 2019 Blindness and Vision Impairment Collaborators; Vision Loss Expert Group of the Global Burden of Disease Study. Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study. Lancet Glob Health. 2021 Feb;9(2):e144-e160. doi: 10.1016/S2214-109X(20)30489-7. Epub 2020 Dec 1. Erratum in: Lancet Glob Health. 2021 Apr;9(4):e408.
  14. ↑ Vision Loss Expert Group of the Global Burden of Disease Study; GBD 2019 Blindness and Vision Impairment Collaborators. Global estimates on the number of people blind or visually impaired by cataract: a meta-analysis from 2000 to 2020. Eye (Lond). 2024 Aug;38(11):2156-2172. Erratum in: Eye (Lond). 2024 Aug;38(11):2229-2231.
  15. ↑ Keenan TDL, Cukras CA, Chew EY. Age-related macular degeneration: epidemiology and clinical aspects. Adv Exp Med Biol. 2021;1256:1-31.
  16. ↑ Zhang S, Ren J, Chai R, Yuan S, Hao Y. Global burden of low vision and blindness due to age-related macular degeneration from 1990 to 2021 and projections for 2050.BMC Public Health 2024, 3510.
  17. ↑ Blindness and vision impairment. World Health Organization, Geneva, 2023. Available from https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment [last accessed 27.6.2025]
  18. ↑ 18.0 18.1 Hu CX, Zangalli C, Hsieh M, Gupta L, Williams AL, Richman J, Spaeth GL. What do patients with glaucoma see? Visual symptoms reported by patients with glaucoma. Am J Med Sci. 2014 Nov;348(5):403-9.
  19. ↑ Kropp M, Golubnitschaja O, Mazurakova A, Koklesova L, Sargheini N, Vo TKS, de Clerck E, Polivka J Jr, Potuznik P, Polivka J, Stetkarova I, Kubatka P, Thumann G. Diabetic retinopathy as the leading cause of blindness and early predictor of cascading complications-risks and mitigation. EPMA J. 2023 Feb 13;14(1):21-42.
  20. ↑ Gordon K, Bonfanti A, Pearson V, Markowitz SN, Jackson ML, Small L. Comprehensive vision rehabilitation. Can J Ophthalmol 2015;50:85-86
  21. ↑ 21.0 21.1 Churchill J and Gudgel DT. What Is an Ophthalmologist vs Optometrist? Available from https://www.aao.org/eye-health/tips-prevention/what-is-ophthalmologist#ophthalmologists [last accessed 26.6.2025]
  22. ↑ Academy for Certification of Vision Rehabilitation & Education Professionals. Certified Vision Rehabilitation Therapist. Available from https://www.acvrep.org/certifications/cvrt [last accessed 26.6.2025]
  23. ↑ Academy for Certification of Vision Rehabilitation & Education Professionals. Certified Orientation and Mobility Specialist (COMS®). Available from https://www.acvrep.org/certifications/coms [last accessed 26.06.2025]
  24. ↑ Yudistira T, Trustisari H. The Role Of Social Workers In Low Vision Rehabilitation Services At The Worth Foundation. Pubmedia Social Sciences and Humanities 2024;2(1):1-8.
  25. ↑ Carvalho PHS, Fernandes AC, Montilha RCI. The role of the speech therapist in visual impairments: perceptions of professionals from a rehabilitation center. Rev. CEFAC. 2020;22(2):e15619.
  26. ↑ 26.0 26.1 Warren M. A hierarchical model for evaluation and treatment of visual perceptual dysfunction in adult acquired brain injury, Part 1. Am J Occup Ther. 1993 Jan;47(1):42-54.
  27. ↑ Muhsin ZJ, Qahwaji R, Ghanchi F, Al-Taee M. Review of substitutive assistive tools and technologies for people with visual impairments: recent advancements and prospects. J Multimodal User Interfaces 2024;18:135–156.
  28. ↑ Signal Centers. Sighted Guide Technique. Available from: https://www.youtube.com/watch?AuGb4yge-ys [last accessed 6/6/2009]
Retrieved from "https://www.physio-pedia.com/w/index.php?title=Vision_Considerations_in_Function_Based_Rehabilitation&oldid=383521"