Lecture: Low Vision Rehabilitation for Patients with Visual Field Loss

Low vision rehabilitation often employs magnification to compensate for reduced visual acuity and central vision loss. However, patients with peripheral visual field loss may have additional functional concerns that are not sufficiently addressed through magnification alone. In this webinar, we will use cases to explore common functional complaints in patients with visual field loss and how these complaints are addressed in low vision management. (Level: Intermediate)

Lecturer: Dr. Micaela Gobeille, Optometrist, New England College of Optometry, USA


All right. Good morning, or, I guess, good evening for some of you, and welcome to our conversation about low vision management for patients with visual field loss. Our conversation today is really going to focus on patients with more concentric visual field loss than on hemianopia or other etiologies but we’ll touch on those a bit. We’ll start with a brief overview of the concepts surrounding management for patients with visual field loss. And spend most of our time toddies cussing specific cases I’ve seen in the recent clinical past and talking about low vision management in these special cases and some of the principals. I think first of all, it’s important to note that visual field loss occurs in a number of different ocular conditions for a number of different reasons. These can include retinal diseases like retinitis or retinopathy. Optic nerve related diseases like optic atrophy or glaucoma or neurological problems in patients with hemianopia. It’s important to accurately and reliable assess visual fields in these patients of course so we can understand what type of field loss they have and how it might impact their function. Standardly we do confrontation visual field. We show fingers off to the side and ask the patient how many fingers are seen. This gives us a gross assessment of the peripheral vision and field loss. We can use formal perimetry techniques like Humphrey visual fields. The patient is placed in a machine that has lights and they indicate when they see a light. This allows us to compare visual fields over time with a high level of detail. There are other kinetic visual field tests we can do with standardized equipment. Such as the Goldman visual field, a test where patients press a button when they see a light. But the examiner controls the light and not the machine. We can be a little bit more varied in our presentation of targets. In patients with visual field loss, there are certain complaints that are more common. Patients might report they often lose their place when reading. They might report missing things off to the side where, you know, if they’re not looking directly at something, they have to really move their eyes around to find it. They might say they can’t see things until they’re directly in front of them. It’s a jack-in-the-box effect, especially, in patients with hemianopia where if they’re walking along, they might not see something off to the side until it’s right in front of them and then it pops into their view and they all of a sudden see it and need to respond to it. Patients can report difficulty localizing objects in their environment. If they drop something it’s difficult for them to find it. They report difficulty with mobility. More frequent trips or bumping into things or have falls related to not seeing things in their environment and losing their footing. Driving can be a significant concern in patients with visual field loss and many states in America do not allow patients to drive if they have significant field loss. So knowing these functional complaints that are common in patients, these are most often elicited during the functional case history portion of a low vision exam. I’m seeing that people cannot see the screen. Is this correct? >> Dr. Gobeille. We can see your screen. I will work on this ticket. >> Thanks, so much, Andy. During a low vision exam, there are a number of different elements that we can go through in the course. So first, we’ll do a functional case history where we typically are picking up on those different functional complaints that we discussed on the last slide with mobility concerns and difficulty bumping into things and there are specific areas within a low vision functional history that I often address. So during a case history, we want to get a chief complaint. Here we find out exactly what the patient is hoping to get from their low vision exam with the hopes we can address that problem on that visit. We then ask about difficulty reading. We might ask patients if they’re having difficulty reading medication labels or books or newspapers or food packaging and all of the different activities have different requirements and patients may have different preferences about how they go about performing these activities. Another type of reading that I will often ask about as well is technology. I want to know if patients use computers or tablets or smartphones. If they do, they want to know if those patients are using any specific adaptations to make them easier to use. If not, I might have some recommendations on how to use these devices as well. I also ask patients about general seeing. If they’re having trouble reading signs or seeing the TV. If they have ever worn distance glasses or find them helpful. And those types of activities. We’ll ask about mobility. Is this a really important one in our patients with visual field loss. Here I ask patients if they have had trips or bumps or fallen or if they’re concerned about any of those things. Sometimes our patients with significant mobility will restrict activities to reduce the likelihood they have these problems and that can be a problem in and of itself. Because if patients aren’t going out and about, this is really limiting their quality of life. I also ask patients about their daily living activities. Do their cooking and cleaning and take care of their laundry and home environment. Can they manage their medications and tell their pill apart. I will ask about work or school for younger students and if they’re having difficulty there. And hobby, do these patients have other important activities they do in their day to day life. We take a detailed and comprehensive functional low vision history during a low vision exam, which is different from you are usual eye exam history. After we’ve gone through the full history, we do entrance testing. And some of the entrance tests are the same as usual. We will do extra ocular motility and evaluate the pupils and do visual fields. There are some tests that are different. First, we do visual acuity testing. The way we do this can be different from a primary care eye exam. Here, we can use special charts for low vision patients that can be used at a closer working distance that allows a more accurate measurement of visual acuity. Quite often I will see patients marked as having hand motion vision from a different provider. But when we see them in the low vision clinic where we have these additional tools to measure vision, we can get a measurement of the vision which is important for finding appropriate refractive findings or using devices accurately and give the patient the sense they have vision in their worse-seeing eye. We next evaluate contrast sensitivity. Most of our world isn’t black on white like a standard acuity chart, so contrast is important to assess how patients perform in these real-world conditions where things aren’t perfect contrast. They start with these nice dark letters and then as they go on through the test, the letters get more and more faded. This allows us with a clue as to how that patient might function. We also evaluate reading using special continuous text reading charts that have full sentences of words. This can be really useful especially when we’re evaluating devices because it gives a more real-world assessment of reading performance than just a near acuity test. It gives us a better sense of whether patients are missing certain elements of the word, the first or last part of the word. That can suggest something about the patient’s function and how we can intervene to help. After this, we do a trial frame refraction to make sure the patient’s vision is corrected the best it can be corrected. We evaluate different low vision devices and technologies based on all of the exam findings we have so far. The acuity, the functional contrast and the history. So low vision management for patients with visual field loss follows the same format that we discussed and we go ahead and evaluate many of the same devices that are evaluated in patients with central field loss if necessary. But there are certain things that we might do for patients with field loss that are more specific to field loss. For patients with visual field constriction, minifier or reverse telescopes can reduce the size of the image the patients see to see more at the same time. We know that any time we’re using a magnifier or a telescope, there is a trade off between magnification and field of view. The idea is we expand the field of view at the expense of magnification, we shrink things down so where he can see more at a time. We can also use peripheral prisms or Peli prisms for patients with hemianopia. These are known to expand the visual field. There are tiny segments of prism that shift things towards the seeing field from the non-seeing field. We put them in front of just one eye. This is beyond the scope of what we’re discussing today with concentric visual field loss, I would feel remiss not to mention it. If acuity is lost, we need to prescribe magnification. If we over magnify, patients will only see a little bit at a time and with that field of view and magnification trade off, if we magnify too much, field of view is small and they may only get a fraction of a letter at a time which can make for very difficult reading. Other considerations in patients with visual field loss reinvolve around training. Some patients with field loss require scanning training to develop systemic strategies to locate and find things in the environment and move their eyes in a specific pattern to localize items. Patients may require orientation and mobility training where they learn nonvisual skills to compensate for their visual field loss and get around and function and find their way when they’re out and about. We’ll touch on orientation and mobility training throughout our cases. I think for now, we’re ready to jump into our first case for a patient with visual field loss and they’re unique functional needs. For the first case, we have a 49-year-old female coming in for her annual low vision exam. A history of optic nerve hypoplasia with nystagmus and strabismus. She is telling us she feels like her vision worsened and she is bumping into things. This is surprising because optic nerve hypoplasia is a congenital condition that we expect to remain roughly stable throughout life. Strabismus and nystagmus for many years and these are not new findings and the optic hypoplasia should be stable in terms of level of vision. We expanded on the functional history further. From a vocational perspective, the patient works as a mental health counselor. Has extensive computer demands especially remitted to her use of the electronic health records. Able to complete her work and do what she needs to do at work but notes her eyes get tired by the end of the day despite her use of built-in computer accessibilities options that make things look larger on the screen. The patient reports when reading, she has trouble tracking her place, especially when reading with prism half eyes that she uses which are strong reading glasses with prism built into them with the base in so it shifts the image out so there is less convergence demand for the patient while reading. So while this patient is reading with them, she is having more trouble keeping her place and she does not note that glasses are helpful on the computer. In terms of mobility, our patient notes she is having more and more trouble and finding herself bumping into things more often. She had orientation and mobility instruction nine years ago and was trained on how to use a white cane. But she really is starting to struggle more and more now even though she is almost 50 years old. She notes that most of the time she does well with her daily living activities. No difficulty with medication management and cleaning. Most of the time she is able to do quite well with cooking. But she notes she recently cut her finger when she was cutting things with a mandolin but felt this was an isolated incident. At this point, she has a few devices in place. She is using prism half eye reading glasses. These are 7 diopters with 9 prism diopter base in, in front of each eye. That base and prism shifts the image out to reduce convergence demand. She uses audio books for pleasure reading. And she has a white cane she will occasionally use for mobility activities. So next I’m going to ask a poll question. Which of the following functional complaints that our first case reported are most common in patients with visual field loss? Difficulty reading and keeping her place? Frequent trips or bumps? Needs for higher amounts of magnification. Distance glasses to resolve the problem or certain combinations of the above? Great. Many of us picked A and B. Difficulty keeping her place and frequent trips and bumps. Most of us who didn’t pick the combination chose at least one of those things. So I think we’re all on the same page here. Moving on with our exam. We completed our functional history and now we want to examine this patient. Her distance acuities are 20/320 in the right eye. 20/1200 in the right eye and 20/320 both eyes together. The near acuity is 0.4 over 2.5 and tilts head back when reading. If ocular motility was examined. She was observed to have a jerk nystagmus with a cyclo rotary component. The nystagmus has a fast and slow phase and there was a circular movement with the eye nystagmus. The patient was observed to have a null point in convergence which we thought was interesting. We did confrontation visual field on her which revealed severe constriction, 360 degrees. We did facial fields at 30 cm away from us and asked the patient to look at our face and asked if any parts of their view were grayed out or missing or distorted. If they’re missing elements centrally, like my nose or eye, that can indicate a central scotoma. Whereas, if they are missing edges of their view; if they can’t see my chin or forehead or ears, that might suggest significant field loss. So fortunately, our patient’s facial fields were full. We also evaluated contrast sensitivity using the Mars contrast sensitivity test pictured here. Our patient read to 0.96 log CS using both eyes together which is the box highlighted by the red box on the screen. This is severe contrast sensitivity deficit. We moved onto trial frame refraction which yielded no subjective or objective improvement in this case at this time. And we next evaluated the patient’s reading. So we used our continuous text card and asked the patient to start at the top and read down as quickly and accurately as she could using a close working distance, she read down to 2.5M with good speed and accuracy. The critical print size is the last line the patient read with good speed and accuracy. Beyond that line, the patient started to really slow down with her reading and could not read any further than the 1.3M line. So the patient’s critical print size suggested she was comfortable reading at 2.5M, 2 times the size of newsprint and couldn’t read past 1.3M which is a little bigger than the size of newspaper print. We went on to evaluate devices. We started with her existing reading glasses. With this device she was able to make it to a 1.6M threshold. With another diopter over it, she was able to read to a 1.3M threshold. So it was a little improved with a little stronger reading glass but not reaching the 1M newspaper size target. Our patient was not motivated to obtain these prism readers at this visit and wanted to forego further device evaluation at this point because she was concerned about her subjective worsening of the visual field. Next we did Goldman perimetry on this patient. We can see the Goldman perimetry findings. For those of you who may not see or do this very often, the lines show what was seen when a patient was shown a specific size light. In this particular case, those three lines were drawn at separate times. So the black line indicates the patient’s responses when the largest target light was brought from non-seeing to seeing visual field. And the patient was asked to press the button when they saw the light. The red line is when the same test was done but using a smaller light target. And then the green line is when the same test was done again using a still smaller target. This was done with a frosted occluder and we confirmed the patient could not see the target with the other eye. We wanted to use a frosted occluder because with the nystagmus, she might have more difficulty if we cover one eye. Whereas if there is a latent component to the nystagmus, it will increase and make the test more difficult. During testing, we saw the patient’s fixation varied related to the nystagmus but she was good at maintaining her place and had greater trouble with the smaller target presentations that we tested. Fortunately, these visual field findings proved to be stable to her last exam. So we moved onto do a dilated eye exam on our patient. Fortunately, there were no concerning findings. She did have a small optic nerve with a double ring sign and cup to disk ratio of .1 round. So you can see a representation of that image over here where the patient has a tiny optic nerve and then you can see large sclera crescents and the area that would be filled in with the optic nerve had it developed normally. We were pleased to note there was no additional ocular pathology at this visit that our patient would need to be concerned about. So our plan at this time was to first reassure the patient on the stability of her visual field testing and the lack of new ocular pathology. Fortunately, for this patient, we had no additional findings. We didn’t need to worry about her having new eye problems. She just felt like she was functioning worse. So while we’re very glad she doesn’t have new pathology that we need to address, we do need to make sure that we do all that we can to improve her function. So next, we recommended updated orientation and mobility training. Our patient told us she is having trouble with tripping over things and bumping into things and having a great deal more difficulty. So updating her strategies that were put in place nine years ago, should be helpful for her. We also felt it was worth considering stronger or different readers to reduce the strain with computer demands and the patient decided we can revisit that at a follow up visit because we spent quite a bit of time evaluating her and she was pretty fatigued after all of this testing. So, orientation and mobility is the topic I’d like to talk about further now. Orientation and mobility training, here where I practice in the United States is directed by a certified orientation and mobility specialist. And it teaches nonvisual skills for navigating the environment which we refer to as mobility as well as strategies for understanding your position in space and how to make your way through it. Which the orientation piece. So the mobilities relates to the patient actively moving through space while the orientation relates more to the patient finding their way and kind of constructing mental maps and finding their way through it. There are a number of different strategies that might be used in orientation and mobility training. The simplest is sighted or human guide. Where the patient has a helper or a caregiver who they are able to depend onto get around. And there are specific strategies that the patient can learn that provide better support and better posture and help the patient get around more effectively. Patients might also be trained to use a long white mobility cane and they can use this to sweep the ground in front of them to detect changes in threshold and low-lying obstacles. So if there is something they can trip over, they can plan accordingly and adjust. There are different echoes and feelings in how the cane is swept across the ground that the patient can use to understand their orientation in space. They can tell if they’re going from one type of flooring to another or detect patterns in how they’re getting around in their usual environments. They can develop strategies to plan their routes. The trainer might help integrate different low-vision devices so if the patient appreciated a reverse telescope or a specific filter, it might be useful to have some training on their devices in their day to day activities. There is so many more things these orientation and mobility instructors will do with their low-vision patients with field loss. It’s comprehensive and crucial for our patient, especially, our visual field loss patients who report trips, bump, falls, and other mobility concerns. I think when we talk about orientation and mobility training, people want to know when do I refer? Who do I refer? What is the cut off? The trick here is that it’s not necessarily what you might expect. So this paper found that potential mobility difficulties can occur in patients with a visual field as large as 70 degrees diameter which is almost half of the visual field which for most clinicians would be surprised by this. It’s a rather large field. In an assessment for mobility, rehab the warranted when the field is between 30 and 50 degrees. For us, patients come in and they might tell us they’re having mobility concerns and I think that with how wide the field’s diameter is, a good take away is we should ask the patients if they’re having new trouble getting around related to their vision. If they are, it’s a clear indication they should be referred for orientation and mobility training. For our particular patient that we’re discussing, she has existing orientation and mobility cane skills from her training done nine years ago but her function seems to change despite the stable vision in ocular health. She is worth getting a referral to orientation and mobility to update her existing strategies. So fortunately, I recently saw this patient for a follow up and she was so pleased to tell us that her refresher orientation and mobility instruction happened and she was doing so much better. She was relieved that she wasn’t tripping or bumping into things anyway and said, you know, I knew how to use that cane but boy do I use it better now that I had this additional training. She was thriving with her mobility skills. However she had broken her reading glasses and ready to revisit this activity and find a new set. At this follow-up visit, our patient’s vision was nice and stable from previous. We saw her 20/320 vision in the right eye and both eyes and 20/1200 in the left. She had nystagmus that was stable. Still had severe contrast sensitivity deficit and at this visit a refraction yielded mild improvement in vision. And she felt she did prefer the small astigmatism correction that we detected on this exam. We moved onto evaluate her reading. Using the manifest refraction that we found at that visit with a plus 6 add over the refraction. We were surprised to see that our patient did a little bit better than at the last visit with a smaller critical print size of 2M and a similar threshold at 1.3M. We then evaluated different options for reading with a plus 8 add our patient had trouble and her reading seemed slow and strained. But with a weaker add, she had better fluency and preferred this than the plus 8. She preferred the plus 6 add without a prism feeling her eyes weren’t working as hard without the prism. We updated the patient’s distance and reading glasses and at this visit she felt she would be best served if we skipped the prism in her reading glasses. It seemed likely given the nystagmus null points, pulling the reading material close was helpful because she could more easily adapt her null point. With the prism, she would have less convergence and less of an impact on the nystagmus. We used a weaker reading prescription at this visit than she was accustomed to wearing. This is another example of a case where over-magnifying can be problematic. And sometimes less magnification is more. At the end of this visit, we also recommended continued use of orientation and mobility strategies and we were quite pleased with how she was doing with hurricane skills. So from this case, it really highlights the importance of orientation and mobility instruction for patients with field loss. And really maintaining that level of performance throughout the life span. This patient has probably been using a cane since she was a child and here she is at almost 50 years old still learning and growing and developing new strategies. So sometimes orientation and mobility training is not a one-time occurrence. It’s something that sometimes needs to be refreshed over time. We noted a few additional considerations in this case. First, we ensured the stability of ocular health for the patient. We also recommended glasses and low-vision devices as appropriate. It’s important for our patients with field loss that we provide the best refractive correction to maximize vision. And we also need to be careful not to over-magnify patients. If we provide too much magnification in a small field of view, this can be prohibitive for our field loss patients. Our next case is a 75-year-old female who is presenting for a low vision exam with a history of proliferative diabetic retinopathy with a retinal detachment in the left eye and ocular prosthesis in the right. She is hoping to improve independence in performing daily living activities. Notes difficulty doing crossword puzzles and reading. Having more concerns with frequent bumps and trips and two months ago she had a fall. She was not injured in the fall and had a long white cane previously but developed some muscular weakness and now she is leaning off to one side and needs a support cane which makes her uncomfortable using a long white mobility cane. When cleaning, she is missing spots. She has burned herself when trying to cook and has help for medication management but would like to do is that more independently. Has some glare sensitivity indoors and outdoors. In this visit, she only is using a lens from a broken hand magnifier. She doesn’t have much technology or devices to help her function. Fortunately, she had recently had a dilated fundus exam with her retinal specialist. She as an ocular prosthesis in the left eye and in the right, stable diabetic retinopathy after treatment with some residual fibro vascular material as you can see in this photo. She had a history of retinal detachment in the eye and the eye was fortunately no longer detached and had extensive surgical scarring in the eye. All of these findings were stable. So we were free to proceed with the low vision exam. At this visit, our patient had no vision in the right eye because it was an ocular prosthesis. In the left there was 2200 vision with a sluggish pupillary response to lights. Her ocular motilities were smooth, accurate, full and extensive. And in the left eye, she had severe visual constriction. We did facial fields again to see how severe her constriction is and if there was central or para central scotomas and they were nice and full. We did contrast sensitivity testing on this patient and her contrast of .88 log CS revealed a severe impairment as you can see indicated on this chart over here. By that red box. We next did a trial frame refraction and found some compound astigmatism which yielded a subjective improvement in the patient’s vision and she benefited from an [inaudible] We evaluated her reading using the manifest refraction in a plus 350 add. And was able to read to 3.2M with good speed and 2.5M at the slow struggling pace. We proceeded to evaluate different low vision devices. This patient was particularly interested in hand magnifiers. We started with a 24 diopter hand magnifier where the patient could read 2.5M. The field of view of this device was restrictive and limiting and didn’t like it at all. The field of view was problematic for this patient, we walked back the magnification a step and evaluated a 20 diopter magnifier. She was able to read down to 1.25M and really liked the device. She preferred it over the previous one. Felt that it was much easier to use and felt like it was something she could actively use in her day to day life. We next evaluated tints and our patient preferred a dark plum tint for the glare sensitivity. So at this visit, we issued a glasses prescription for full-time wear and given the fact that our patient is mono-ocular, we recommended impact resistance Polycarbonate lens material for protection. So if something hit her in the seeing eye, she would have a lens to protect it. We recommended the 20 diopter hand magnifier and the plum filters for glare control. Recommended orientation and mobility instruction and we’ll talk a little more about how that is different for our second patient than for our first patient. And we recommended some daily living skills training. She was requiring a letter stating that she was legally blind in support of some accommodations that she needed related to her apartment building. In this case, orientation and mobility training needs to be modified a bit. Long cane training may not be feasible alone for a patient with physical comorbidities like muscle weakness. Our patient was telling us she couldn’t use the long white cane because she needed more support. There are different ways to do this. Sometimes the patients use the long white cane in addition to different support strategies. They might have a long white cane plus a support cane or a long white cane plus a walker. Some patients aren’t able to do this. I had a patient the other day with lower back pain that pro-colluded her for using devices in that hand. So she was using just the support cane. Sometimes patients need a walker or rollator because its provides previews of upcoming thresholds. If they can’t sweep the floor with a long white cane, a walker gives a preview of what is coming in the next foot. If the walker is bumping around or going over an edge, they will realize it and correct and adjust. Some patients use a support cane, a short white cane or regular cane to sweep ahead a little bit or feel where the next step is when going downstairs. Or patients might get a white support cane with a red tip that indicates legal blindness and at least provides identification so that if patients are walking down a busy city street and they need support and they’re also visually impaired, others will be aware of that impairment and hopefully react in an appropriate way to not create problems. Daily living skills training is also important for this patient who is telling us about the difficulties she is having with the cleaning and cooking and her medication management needing support. There are a number of different strategies that could help a patient function with these daily living activities. You can see pictured here a liquid level indicator, that orange device in the upper right part of the screen, this device can be hooked over the edge of a cup and it will beep when it’s about to overflow so the patient doesn’t overfill the cups. There are protective gloves to wear when cutting to prevent them from cutting themselves. And some patients may use a special chopper rather than cutting things manually themselves to reduce the risk of cutting themselves. There is high contrast cutting boards. This one is white on one side and black on the other. And patients can cut dark colored things like broccoli on one side and cut light-colored things like potatoes or chicken on the other side to make it easier to see due to contrast. Patients might also use different customized marking strategies for their medications. They might label it with large print or use rubber bands to indicate when they’re supposed to take them. So here is our next poll question. True or false, orientation and mobility training is only useful for patients who do not have any problems stemming from musculoskeletal comorbidities like muscular weakness or arthritis? All right. Great. Most of us agree. Orientation and mobility can be helpful in people even who have musculoskeletal issues that prevent their use of a standard long white cane. From this patient, we’ve seen that orientation and mobility training can be appropriate in patients with physical comorbidities that affect mobility but different approaches might be necessary. There are also other strategies that can help improve daily living activity performance which might be compromised for patients with field loss. And it’s important to continue to recommend low vision devices and glasses when it’s appropriate and always to use the minimum amount of magnification possible. So we have one more case today. This is a 65-year-old female presenting for a low vision exam with a history of bilateral occipital lobe infarct following a stroke. The left occipital lobe infarct was chronic but had a new right sided infarct about a month ago and came to this visit with her daughter saying she is having so much difficulty. Can’t read the bible anymore which is troubling to her. She is unable to do her daily living activities as independently. Is depending on others. Hasn’t had trips or bumps or falls but she is restricting her activities and not going out at all and barely leaving the armchair. She has really reduced her life space. At this point she has a lot of emotion mall problem, she is depressed and not eating and the daughter is really worried about her. Her distance acuity were 20/25 in each eye. Turned her head left when reading and had trouble finding the letters on the screen. But she was able to do it with enough time and help. Her vision did not improve with refraction and she was able to read small print on near acuity testing but it was very difficult. We evaluated the contrast sensitivity which was moderately impaired at 1 log CS as indicated by the red square on the chart. The pupils were full and normal. Her eyes got to all of the places they needed to go. The fixation was unstable. She would lose sight of the light target throughout the testing. Confrontation visual field showed profound constriction, 360 degrees in both eyes. And we can see that visual field test at that visit here. We see Humphrey visual field print outs showing severe constriction in the left eye worse than the right. Explaining why she was having so much trouble functioning with her vision. We evaluated continuous text reading and she read down to .4 over 4M but really struggled. She kept losing her place. She kept reading isolated letters and getting jumbled up and lost on the page. We thought about using a line guide with her to keep her place but she felt so frustrated and depressed and overwhelmed, that she didn’t want to revisit anything that would help her keep her place for visual reading. At this visit we recommended orientation and mobility instruction as we’ve discussed quite a bit throughout this talk to help our patient find her way despite this restricted visual field. And help her get out and about and stop limiting her activities. We recommended daily living skills training that might help her find strategies to do her daily living activities for effectively and independently. We recommended OCR technology to use for reading. So there are a number of different devices that have this capability and this will read things allowed for patients rather than having them need to read it visually. So based on how much difficulty our patient was having with using her vision and her general level of frustration, we jumped right to having things read aloud to her. With 20/25 vision and with the ability to read down to .4M, she could read small prints. So making it bigger wouldn’t be helpful. But finding her way around can be frustrated when you have such a high level of field loss. We talked to her about different smartphone apps: You can see an app called seeing AI which is free on iPhones and this can read things allowed to you from medication labels and food packaging. It has a number of other functionalities as well. We also showed her some stand-alone OCR technology with these individual devices that will scan a document and read it aloud to her. For this patient with profound visual field loss, sensory substitution was most appropriate because she had such a high level of frustration. And so much field loss that prohibited her from finding her way around. We next talked to our patient about her emotional adjustment to vision loss. Given the severity of her emotional adjustment and how much trouble she was having and her level of depression, she fortunately already had a referral put through to psychiatry. We counseled her on the importance of following up with that referral and making sure she is seen and managed so she can start feeling better. We also talked with her about the prognosis of visual field loss from strokes. And the importance of continued care. We plan to repeat her visual field tests in a few months. The reason for this is because spontaneous recovery or gaining back a bit of lost visual field has been documented in patients with homonymous hemianopia and our patient has two homonymous hemianopias at once. When spontaneous recovery occurs, it’s described as a small area of recovery. Patients are not getting back a large amount of visual field. It’s been described like a finger-like extension. Research has shown it’s more commonly seen in lower and temporal crescents. Here we can see a visual field from a different patient. This is not the same patient. This is another patient who initially had a complete right hemianopia and then the areas that are circled but that yellow oval, that’s the area that the patient regained over time. That is the area of species recovery. Where they previously had no perception in that area, now they at least have a little bit. So time goes by. Our patient left, we made our recommendations and she comes back nine months later feeling that her vision has in fact improved since the last low vision exam. She is still struggling with reading and doing more with the daily living activities and her mobility is improving as she gets out there more and gets help from a physical therapist who is doing support with muscular strength and training. She is doing much better emotionally with good support from her psychologist and really much improved. At this visit her acuities are stable, the contrast sensitivity is 1.16 which is maybe a couple of letters better than the last visit. The biggest change we saw at this visit, while she still had profound constriction in the right and left visual field, the inferior left field was now full. So we saw her visual field before. This is what they looked like initially. And at this follow-up visit, she had this area in her inferior left field she had gained back. You see this area where there was spontaneous recovery in the left eye as well as the right eye. She has this wedge of vision which she previously barely had any vision. So we were quite happy to find this. We then evaluated her reading using the continuous text reading card again. Here she had good speed and fluency, enormous improvement since the last visit likely related to the recovery of the visual field. She made I down to 1.3M size print which is just a little larger than newspaper print. And we evaluated different reading apps with her. She preferred a plus four add which is down to .8M which is smaller than newspaper print and receptive to using this device when she didn’t have other options. However, she was really keen on using a hand held magnifier, with a 6 diopter magnifier, she read down to .5M or half the size of newspaper print and she was thrilled. She read some medication labels that were able for her to evaluate in the office. She read different packaging and instructions and was excited about it. At the conclusion of the visit, we educated our patient abnormal the improvement of vision. And while we didn’t expect any further improvement, we were so pleased that improvement had occurred. We recommended a set of reading glasses for reading a large print bible with direct task lighting. Given the decreased contrast sensitivity, she needs the lighting to compensate for how much things are washed out and needs brightness to see well. She obtained the 6 diopter hand magnifier. She didn’t want to leave the clinic without it. We recommended continued daily living skills training. For this patient, we can see that functional goals can be achieved different ways but it depends on the level of visual field loss. Initially this patient had profound constriction where visual reading was not realistic for her. However, over time with luck and spontaneous recovery, she was able to read visually using low levels of magnification. It’s important to maximize central vision and recommend devices where question. So to conclude from today, visual field loss can occur from a range of ocular conditions. And this has significant impact on patient’s function that we spent some time discussing today. It’s critical to determine patient’s functional goals in order to direct where we’re going during a low vision exam. Orientation and mobility instruction can be really critical in order to help patients find their way around and avoid trips, bumps, falls and restriction of their activities. And there are other interventions that we need to think about. We want to make sure that we optimize distance vision through refractive correction. We want to provide the lowest level of magnification possible to accomplish a desired task. And we should think about whether patients are struggling to perform daily living activities and recommend training if necessary. So I’d like to thank you for your attention today. And I guess we can now open the floor to any questions. Okay. I’m seeing a question about why I opted for a Goldman and not an automated perimetry test. This is probably related to the first case we discussed today. For that patient, he had, sorry, she had some pretty severe visual field loss, 20/320. Given the severity of the visual acuity loss, she might have difficulty seeing the small fix sakes target. The fixation monitoring feature in a Humphrey visual field was unlikely to work for this patient because of the nystagmus. It would not be able to track the eye because the eye was constantly moving around. Goldman visual fields are nice for low vision patients that might have difficulty responding in standard ways to the Humphrey visual field because you can modify it to suit the visual needs further and if they have comorbidities that make them slow to respond, you can factor that in and present targets slower. They also provide a larger field diameter that they assessed. A Humphrey visual field at 30-2 only addresses the 30 degrees on either side of the fixation. Whereas, the Goldman visual field, really assesses the whole field of vision and gets all the way out into the far periphery. It gives you a more comprehensive idea of any visual field loss. There was another somewhat related question about different visual field tests. I was asked, do you perform a 10-2 Humphrey visual field on patients with gross field loss to make sure you evaluate the central 10 degrees in more detail. That’s a great question. It depends on the patient. I’m picky with my visual field choices. A 10-2 is a great option especially for patients that have that very small, less than 20-degree diameter. It’s particularly helpful for our end-stage glaucoma patients where you want to make sure that you’re assessing for any changes in the visual field and great detail in that very small area. I’ve seen a couple of questions about reverse telescopes. So a reverse telescope is essentially a telescope held backwards. So rather than enlarging what you’re looking at and magnifying the view, it minimizes it and makes its smaller. There are also some kind of stand-alone reverse telescopes or minifiers that work this same way. They’re designed more for that task. I see a question about the difference between using prismatic magnifiers from non-prismatic magnifiers. There were a couple cases that we discussed today, there were a couple that used strong adds with prism and the prism is put into the glasses base in. It’s shifting the image out. There is base in prism in front of each eye. The patient will not need to converge their eyes as much to focus on things that are up close. If you bring reading material closer, the patient’s eyes need to pull closer together in order to have binocular single vision. By using that prism in the glasses, it pushes the image outward so they don’t need to work quite so hard to converge to that distance. I’m seeing a question about how to know how many diopters to prescribe for a magnifier. There is a number of different ways to do it and a couple of really great lectures on the Cybersight library from past low vision lectures. I usually use the inverse of the critical print size to determine my starting point. If a patient’s last good smooth fluent reading was holding the print material at 10 cm and they read 1M, I would do 1M divided by .1 to get my predicted add. I’m seeing a question, if a patient has trembling, what device is best. If a patient has a hand tremor or unable to hold things stable, they might have difficulty using a hand magnifier where things move around. If you’re using a magnifier and your hand is shaking, it’s hard to keep that view. So stand magnifiers may be more appropriate. There are patients that have head tremors where their head moves and these patients may not do as well with spectacle based approaches and do better with hand stuff. I’m seeing a question about assessing visual fields in children. This is definitely a challenging endeavor. It depends on the age and maturity level of the child. Some children are able to do a Goldman visual field if you reframe the question a little bit. Your zapping spaceships or catching fairies or some alternative way to think about it so it makes it more of a game. There are a few publications out there about different methods to assess visual field in children. In our clinic we use a flicker wand. It’s really just a light at the end of a stick that we use to do a modified confrontation field test. But engaging the child in a game-like approach for assessing the visual field seems to be useful. I’m seeing a question about why cataract is a major cause of low vision. Nearly everyone develops cataract to some extent past a certain point in life. It’s a yellowing of the lens inside the eye. So it’s very common for this to occur in people of all ages. In older ages, excuse me. UV exposure increases the risk of cataract and that can further progress the condition. And you know, cataract surgery is very effective in resolving vision loss from cataract. I’m seeing another comment, people with progressive field loss, it can be helpful to introduce sensory substitution and orientation and mobility training early. I firmly agree with that. Sometimes the challenge is getting patients to accept orientation and mobility training earlier on. There can be some stigma and reluctance to accept mobility training in patients with field loss because they don’t want to be identified as having a visual impairment. Without a white cane they look just like everyone else and nobody would know they are visually impaired. That sometimes slows the accept tense of orientation and mobility training. And introducing sensory substitution and encouraging patients to use optical character recognition software along with visual information can be useful. A lot of times in younger patients with RP, especially those with significant computer and vocational goals, I might recommend using built-in read along functions. So as they’re writing papers, they can do some from an auditory perspective and others visually and integrate the two together. There’s a question, can hand-held magnifiers be beneficial in end-stage glaucoma with low vision. It depends on the level of minimal vision. I have patients with end-stage glaucoma who use a hand magnifier to check tiny things but they have a way to use their vision. If they have profound field loss and their acuity is profoundly reduced, we might be limited with hand magnifiers because you can only get up to a certain level with a hand magnifier. And especially in glaucoma, contrast sensitivity is often reduced. These patients might benefit from a portable electronic magnifier that can make things brighter and bolder. I’ve seen a few questions about patients with hemianopia. I’m on the last case in the presentation, did have hemianopia. I didn’t want to focus on that in this presentation today, it’s kind of a separate set of interventions. For patients with hemianopia, the preferred choice for managing mobility concerns is peripheral or PELI prisms which are segmental prisms that fit on the patient’s glasses in a specific way. There is a ton of research backing their use. They’re very, very useful but some patients have trouble using them and they take some training and adaptation. All right. Well, I think that’s it for today. Thank you all for your attention and for joining me.

Last Updated: December 20, 2023

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