Distinguishing Between Visual Field Cut (VFD) vs. Inattention & Neglect – CVA/Stroke

What is the difference between visual field cuts (VFD) and neglect? What is a field cut? What is inattention? Why does it often occur on the left side? Is there such a thing as right-sided neglect? How do patients present differently for all of the above? How does a field cut or neglect affect ADLs? IADLs? How does treatment look like? What can occupational therapy do? All of these questions answered in this post!

Background

Clients with visual field deficits and/or neglect may appear to be unware of their affected side of their body or environment. They may sit abnormally with their head turned from the center, not notice an arm dangling or getting stuck on the wheelchair, bump into objects in the environment that are clearly there, or neglect to do things such as eat from one side of the plate or shave their entire face.

How We See

How do we all “see” the world? First there has to be good lighting, e.g. sunlight, artificial light. In complete darkness, we tend to stumble or trip on things. Our eyes then perceive the world with light and transmit this information to our brains. At one point, the information crosses at the optic chiasm for optic nerves. In the stroke world, left brain (infarct) generally affects the right side (function) – right brain (infarct) affects left side function.

Vision breaks down more complex into visual acuity (focus), contrast, depth perception, visual memory, and so on. Any disconnect or damage to the process (including at the brain) could result in a difference in how someone perceives the world compared to someone with say, normal 20/20 vision and no stroke.

Visual-Perceptual Hierarchy

A useful model for visual perception is the visual-perceptual hierarchy in the central nervous system.

Notice that attention builds on the foundation of oculomotor control (e.g., cranial nerves), visual fields, and visual acuity – these all work together before we can have visual attention. This makes you appreciate how complex our visual-perceptual system is. For a deeper dive into visual-perception and CVA, AOTA has an article on the visual perceptual hierarchy.

How Visual Field Deficits and Visual Attention Deficits Affect Function

OT is all about function through occupations!

If we cannot “see” or perceive the world differently, then it can affect our function. Extreme examples include reading, watching TV, and driving. But think about other more subtle examples such as ADLs. It is kind of like getting up in the middle of the night to use the bathroom. Think about all the risks such as falls that occur.

A field cut or neglect could affect any ADL including eating, brushing our teeth, grooming, using the restroom, showering, and dressing. Dressing (once thought of as easy and overly learned) can become a very difficult task for someone who suffered a stroke because of this attention-deficit in addition to physical deficits such as hemiparesis and poor balance. When combined, getting dressed by yourself can seem impossible.

Doesn’t this really make you appreciate your eyes and their job in function in this world?

Visual Field Deficits (VFD)

The visual field is the external (to the body) world that we see when looking straight ahead (without moving your eyeballs in any direction). When we do move our eyes, our visual field expands to see even more of our world. Our normal visual field is 60 degrees superiorly, 75 degrees inferiorly, 60 degrees towards the nose (nasal), and 100 degrees to the side (temporal). We normally see binocularly (as opposed to with one eye).

Damage to any part of the cells in the retina to the optic pathway of the central nervous system for visual processing results in a visual field deficit (VFD). Therefore, the damage can occur anywhere along this path – any type of VFD is possible after a brain injury.

Put simply, a VFD is a “blind spot” or blind area within the normal field of one or both eyes.

Homonymous hemianopsia (homo = same, hemi = half, anopia = blindness) (Diagram D./G./H.) is a loss of vision in half of the visual field in both eyes – more common with CVA. The loss of vision is the same for each eye such as loss of half of vision on the left side in the left eye as well as the left side in the right eye.

Most hemianopias are caused by damage to the posterior cerebral artery (PCA), but a middle cerebral artery stroke (MCA) can cause this as well.

Daily performance can be affected by VFD due to impairment in the search pattern. You know, when you read from left to right or cross the street and check left-right-left for cars. What happens with VFDs such as hemianopsia is that the search pattern narrows instead of being naturally wide.

An example of how you do this is when you read text on your smartphone screen, your search pattern is very narrow compared to say reading from a chalkboard (wider search pattern). If you read a chalkboard with the search pattern used for a smartphone, you would miss a lot of visual information. The same occurs in someone with a VFD who turns their eyes and/or head not enough to overcome the blind spot in their eyes.

Humans are very smart and it can take a lot of visual processing power to do basic things, but we become accustomed and find patterns or take shortcuts. If English is your first language, you have mastered the alphabet, words, grammar, context, and so on when you read. Imagine learning a foreign language with new characters, having to read them from right to left, with syntax reversed, not to mention some meanings do not translate to your native language – it becomes very difficult and cognitively taxing for you to process. Similarly, we have adopted perceptual completion to reduce cognitive processing load.

Perceptual Completion

Perceptual completion is when the CNS samples a visual field and internally completes the external world based on expectations.

You don’t need to “see” all of the features to “know” or that they are there. This allows you to see the world and even read specific words very quickly. When we use perceptual completion, we do not scan as wide in our world and drastically increases the speed of visual processing that we are comfortable with – important in our fast-paced and dynamic environment such as crossing a busy intersection.

VFD Deficit Phenomenon

Someone with a VFD may not necessarily become aware of their absence of vision and become fooled by their perceptual completion and adopt a narrower search pattern than they should. This results in gaps in visual information and resulting deficit functionally such as with reading. Someone with a VFD may think something like a doorframe is not there and run into it on the side. Other times, objects may seem to be appearing and disappearing (which we know is not the case in reality) – on the affected side.

Oftentimes, the search pattern in someone with a VFD is restricted to midline (center) of the body and not our peripherals compared to superior/inferior. Now you can see how the occupation of driving can be very dangerous for someone who has a VFD. What if someone becomes aware of their VFD and consciously tries to compensate? Visual searching can still be slow and delayed according to research. Thankfully, VFDs can be overcome with practice. ADLs are not as difficult to overcome as IADLs such as shopping in a busy environment or driving.

Think about how this can affect someone psychosocially – you are now slower to read or process information. It can cause anxiety or depressed, even overwhelmed – causing someone to withdraw and lead to occupational deprivation. That’s no good.

VFD Assessment

OT’s often can screen for VFDs with a simple confrontation test. The OT sits in front of the client and has them fixate on a target as stimuli, e.g. penlight, is presented in each visual quadrant. A client may also describe a blind spot in one/both eyes. If show them a VFD diagram like the one above, they may say they have one of the VFD presentations.

VFD OT Intervention

Research has shown that training can be effective in increasing a person’s ability to compensate a visual field deficit (Gianutsos & Matheson, 1987; Rossi et al., 1990).

This is more easily achievable assuming no deficit in oculomotor dysfunction, say due to damage from a cranial nerve injury.

OT’s can train clients with VFDs starting with ADLs and working their way to IADLs. To begin, clients should have insight into their VFD. Once they become aware they have a VFD and understand the perceptual completion phenomenon, they can then work on rehab for their VFD. The client learns to adopt a wider scanning strategy more quickly, efficiently, and without reminders or external cues – to become more independent from assistance of the OT. The attention of the world shifts rapidly between the central visual field (middle) and peripheral visual field (left and right sides) through wider scanning.

Once clients have mastered scanning in a static (non-mobile) environment, they can then begin to integrate mobility (walking) or more complex use of our body to complete more difficult IADLs, e.g. community mobility or driving. For all this to occur, clients need to look and turn their heads both quickly and far enough to be effective.

VFD Intervention Ideas

– for a wider search pattern. Narrow search such as iPad games may not necessarily encourage large enough search pattern but could still work on improving speed.

• Sports games, e.g. balloon volley
• Laser pointer therapy, Laser tag
• Playing card matching on a wide surface area
• Blowing bubbles
• Pointing out objects in environment/scavenger hunt
• Narrated walk, counting objects e.g., hand soap dispensers
• Shopping activity

Visual *Attention* Deficits

Now let’s differentiate visual attention deficits such as inattention and neglect from VFDs. Visual attention is higher on the visual-percpetual hierarchy than visual field function, and therefore, more complex and difficult to overcome, in general.

With inattention, there is not necessarily an issue with the eyes or perceiving visual information.

Note: A VFD can occur simultaneously with a visual attention deficit such as neglect. In these cases, it can be difficult to tease out.

Inattention results in a deficit in the search pattern of the environment, while similar to VFD – inattention is more of an… attention issue. Hemi-inattention is a visual search deficit from right hemisphere infarct can result in decreased searching of the left half of the visual space. The client no longer uses a left to right visual search pattern and confines their search to one side, such as the right. The client would therefore miss vital visual information on the left, resulting in visual inattention.

Left vs. Right Inattention

Due to the way that the brain is wired on each side, left inattention and neglect occur much more often than “right inattention”. The brain has built in redundancy for attending to the right body and environment (since both left and right lobes attend to the right). In contrast, only the right side of the brain can direct attention to the left body/environment. Therefore, infarcts to the right side of the brain often results in left inattention and neglect.

Some argue that right inattention does not exist, however, in practice, I have observed signs of right inattention too.

VFD vs. Inattention

• Hemi-inattention is often confused with VFDs.
• Both conditions may cause a client to miss visual information on one side, but why they do so is different.
• Clients with VFD may attempt to attend to the environment (e.g., left side), but have blind spot (not move their eyes enough) and are fooled by perceptual completion and not notice the entire scene.
• What’s tricky about VFD is it can sometimes be perceived as inattention because the client misses information on one side.
• In contrast, clients with inattention have normal eyes but processes by the brain make it difficult for them to attend to the left (or right side). It’s as if one half of their world or body no longer exists. Typically, no eye movement or head turns will be attempted towards the deficit side. However, if you were to ask a client with inattention to “scan left”, they could do so. Physically there are no occlusions or blind spots in their visual field.

Neglect

• When clients have a combination of VFD and inattention, it is called visual neglect. Neglect is a more severe deficit to overcome due to the involvement of VFD (narrow search pattern and poor perceptual completion) and inattention (less likely to even attend to one side at all).
• Clients with neglect may not move their eyes past midline, turn their head, neglect limbs, parts of their body, or the environment.

Complications and Contributors of Inattention & Neglect

• Poor insight or denial of deficit
• Not slowing down and taking time to process the scene
• Psychosocial – adjustment to disability, depression
• Poor sleep and attention (important for CVA recovery)
• Medication side-effects
• Medical comorbidities (e.g., peripheral neuropathy)
• Diagnoses such as ADHD/ADD
• Pre-existing visual deficits (e.g., low vision due to old age)
• Impaired senses such as from old age (auditory, sensation)

Outcomes and Interventions

• Consider if the client is: initiating an organized search strategy, can they do it with a good response time (not too slow), do they obtain complete information of the scene, is it identified correctly and consistently?
• As VFD and hemi-inattention are not the same condition, it is necessary to distinguish between the two to have an effective intervention plan.
• This can be difficult as some screens for these deficits result in the symptoms and the two can also occur together.
• Rehab for both conditions generally includes scanning, which involves turning towards the affected side to process that information. Light house beam scanning strategy is typically used.

Screening / Differentiating between VFD and Inattention

• Observation with ADLs.
• Screening with specific tools: clock drawing, single letter search (crowded), letter cancellation, describing what they see in environment, laser pointer in environment, or with biVABA.
• More often, clients with left hemianopia may utilize a (1) narrow left to right search pattern, (2) attempts to search towards affected side.
• With VFD paper and pen tasks, more errors would be noted on the left of the page.
• Carefully watch how a patient completes letter cancellation screens as a patient with a field cut and neglect will have similar looking results when completed. VFD – scans both sides, but may be narrow search vs. inattention – more random, quicker, or does not turn head.
• In contrast, hemi-inattention would result in asymmetric (disorganized, random) search pattern and may be completely confined to one side; no attempts to direct search to affected side.
• Another clue is that clients with inattention may often not rescan deficit side, check for accuracy, or complete the task quickly with a confident level of effort.
• A client with VFD may put in a level of effort more appropriate for the difficulty of your task.

General Interventions and Considerations

for VFDs, Inattention, and Neglect

• Promote scanning and efficient search patterns:
  • Left to right
  • Top to down
  • Clockwise or counter-clockwise
  • Wide (not narrow)
  • Turn head or change body positions to overcome
• Check work for accuracy
• Sensory stimulation of affected side (e.g., weight bearing)
• Crossing midline
• Bilateral extremity use
• Use compensatory techniques such as bright tape, rearranging environment (e.g. client sits so that doorway is on deficit side, but phone (for emergencies) is noticed on non-deficit side).
• Repetition and practice
• Engaging activities are better e.g., card games, board games, puzzles, laser pointer tag, needlecraft, sports games – as opposed to paper and pen tasks and drills.
• Check out our favorite OT intervention hack for working with clients who have VFD or neglect using readily available and cheap Laser Pointers.
• Vision on deficit side may be partially occluded to promote attention to deficit side, e.g. with tape over lenses. Be sure lenses are removed when session is over to not cause issues with non-deficit side.
• Practice function to facilitate carryover with ADLs, IADLs, work, school, etc. – real-life is best. Examples include grocery shopping activity or cleaning room. Take your client to the cafeteria, gift shop, outside, in a busy hallway, in the community.
• Promote carry over in different (non-controlled, dynamic) environments with spaced practice.
• Decrease level of assistance and cues, encourage staff and team to do the same.
• Grade up with distractions, enforce time constraints, widen search required in the scene.
• Incorporated mobility and reading, or other dual-tasking and distractions.
• Decrease task lighting to grade up (but ensure safety).
• Self-monitoring and assessment, debriefing client about their performance in respect to safety (most important), errors, accuracy, time required to complete task, etc. to promote engagement and motivation to achieve personal goals.
• Tracking results and promoting client participation and accountability.
• Set realistic expectations for client and educate caregivers of deficits (including environmental adaptations for safety, social engagement for intervention through games and reinforcement, educating staff to carryover learned strategy and exercises).
• Modify environment as needed (rearrange), remove hazards, place reminders for staff and client, reduce distracting patterns, improve task lighting.
• Consider recording performance (within HIPAA and policies) with video playback and review for teaching.
• Collaborative approach with PT, SLP, Nursing, Caregivers.
• Be creative! – this post will help you build a foundation and with experience, you can think of some fun and engaging intervetions for your clients with VFD, inattention, or neglect.

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