As ophthalmologists, it's tough to fully appreciate the impact glaucoma can have on our patients. Many doctors ask patients whether they're noticing any impact from the disease, but don't ask about specific problems they may be encountering. At the same time, patients don't always want to talk about problems they're having. For example, they may not tell you that they're having trouble driving because they may believe you can take away their license. Confounding things further, the effects of glaucoma, like the disease itself, come on slowly over a period of 10 or 20 years and usually are encountered by older individuals who may have other medical conditions, making it more difficult to know the cause of a specific symptom. So getting an accurate report from a glaucoma patient about the impact of the disease may not always be easy, even if we make the effort. The effort, however, is worth making.
One key reason that it's important to understand how and when glaucoma impacts your patients' lives is that any time you're treating a patient with glaucoma, you're either doing something to the patient or asking him to do something—and every alternative comes with a risk, a cost, an inconvenience or some combination of the above. For example, a patient may have high intraocular pressure or other findings that are suggestive of glaucoma, and you may ask the patient to undergo a laser procedure or take drops. The question is, how much of a problem are you (hopefully) preventing by asking the patient to do this? This risk/benefit balancing act becomes even more important when you're suggesting that the patient undergo surgery, where there's always a risk of vision loss—and in the case of trabeculectomy, a lifelong risk of infection.
Treating glaucoma is very different from treating other ocular diseases such as cataract. If you're treating a cataract, you wait until the patient complains about his vision and then remove the cataract. Ninety-nine times out of 100 the patient is happier after the surgery and stops complaining. (The one in 100 who still complains usually teaches us something!) In contrast, when treating glaucoma, the goal is to prevent patients from getting worse. So when deciding which treatment to recommend, you need to know at what point patients are likely to feel a concrete negative impact from the disease, and how affected they're likely to be. It's an equation: Let's implement treatment A, to prevent consequence B. How aggressive A is should depend on how bad B is.
Quality of life is hard to define, and the impact of glaucoma on quality of life is even harder to define, because the effects of glaucoma can manifest in so many different ways.
For that reason, I'd like to focus on a few specific ways in which glaucoma may eventually cause the patient difficulty.
Studies have asked people with glaucoma and other forms of vision loss what's most important to them in their life. Typically, they cite reading and getting places (i.e., driving and walking). So, when you decide how aggressively you need to treat a given patient—and when you talk to them about potential consequences of the disease—these are the areas it makes sense to focus on.
Impacting Driving Ability
Loss of peripheral vision eventually undermines our ability to drive safely. Even relatively early glaucoma can make it difficult to see pedestrians,1 while more advanced disease can infringe on central vision, with obvious negative consequences. One of our studies found that greater amounts of visual field loss in the healthier, less-damaged eye was associated with worsening driving outcomes.2
Patients handle this decrease in vision in different ways. Some will complain about increased difficulty driving, but some won't, making patient complaints an unreliable gauge of how glaucoma is affecting this area of their lives. Some will manage to continue to drive safely despite the handicap; some will drive hazardously and have more frequent accidents; some will cut back on the driving they do; and some will stop driving altogether.
How much more accident-prone an individual with glaucoma may be isn't clear. Certain studies have found that glaucoma patients have several times as many accidents as individuals without glaucoma,3-5 but other studies have found no difference between the groups;6 one study even found that glaucoma patients had fewer accidents.7 (The fact that some glaucoma patients give up driving may account for the latter study; the poorer drivers may simply be eliminating themselves from the data pool.) Other studies tested subjects using either driving simulators or on-the-road tests and found that people with glaucoma may display certain unsafe tendencies.1,8
Of course, the impact of the disease on the patient's life becomes far greater if the patient decides to restrict the activity or give it up altogether. Many elderly individuals with glaucoma simply stop driving, and this can have a huge impact on quality of life, especially if the patient has no one else to rely on for help getting to the store, to church or to visit friends. The seriousness of this is reflected in studies that have found that discontinuation of driving is associated with a five-fold increase in the likelihood of being admitted to a long-term care facility.9 All of this makes glaucoma's impact on driving a difficult conversation to have with your patient.
Nevertheless, you don't want these patients putting themselves and others at risk. Patients who have lost more than half of the visual field in both eyes clearly should not be driving, and those patients would hopefully agree. However, legal guidelines for what constitutes driving impairment sufficient to revoke a driver's license vary from state to state and region to region. Furthermore, those guidelines may be very vague. So, even if you feel a patient should no longer be driving, you may not be in a legal position to stop him. Despite that limitation, we should be discussing this issue with our patients more often than we do.
Data from some of our studies can help to serve as a barometer for what constitutes the most serious danger in terms of driving ability. We found, for example, that 80 percent of older glaucoma patients with little or no visual field loss in the better eye were still driving. That's not too much different from the percentages for older drivers who don't have glaucoma. However, more than one-third of subjects who had a mean deviation between 3 and 9 decibels in the better eye had stopped driving; that's almost double what you would expect in a general older population. When the visual field mean deviation was worse than 9 decibels in the better eye, more than half the subjects had stopped driving.2 (You have to wonder whether the remainder of that group is still driving safely.) At the very least, these numbers can act as a springboard for starting a discussion.
While we'd often like to discuss matters of driving with family members, there are limitations as to what we can say because of health information guidelines. Basically, you need the patient's permission to share any information about the patient's situation, even with a spouse. If the person in question is in the room with you during the exam, she's likely to overhear your discussion with the patient and become involved; but in that situation it's implicit that the family member is part of the conversation because she was invited in. However, I don't believe you can call up a family member and say, "I don't think your father should be driving."
One option is to suggest a driving evaluation, if either you or the patient are concerned. In some states these are available with no binding results in terms of affecting the subject's driver's license, and the results often make the correct decision obvious to everyone involved. The reality is that different patients will have different levels of driving skill regardless of their disease level; a 50-year-old will probably manage a given amount of field loss better than an 80-year-old, and a person who's healthy, smart and alert will probably do better than a person with multiple ailments. So a real-world evaluation may be the best way to determine whether an individual really is still safe on the road.
In either case, a non-binding driving evaluation can give a concerned patient, doctor or family helpful, impartial information.
Glaucoma's Impact on
When we think of reading as a task, we think of it as primarily involving central vision. However, one study that looked at the reading difficulties people complain about found that many people with glaucoma complained about difficulty finding the next line.10 So it may be that people with glaucoma have no problem seeing what's right in front of them, but when they need to scan a page or search for specific information, they have trouble.
One of our studies looked at how well people read by measuring their reading speed.11 We found that most people with glaucoma did as well as those with healthy eyes, at least over a short period of time, until the glaucoma became so advanced that it af- fected their central vision. However, these results are at odds with what individuals with glaucoma say about their reading. Studies have found that people who have visual field loss in both eyes because of glaucoma do complain about reading difficulty.12 Reasons for this discrepancy are unclear, but it appears that subjectively, glaucoma does interfere with reading even before the difference shows up in tests of reading speed.
What can a patient do if he's having trouble reading? No clinical interventions have been proven to help, although common strategies used with other conditions may be beneficial. Recommend a focused light directly on the page if the patient is not complaining about glare; books with larger print could also be useful. Low-vision service evaluation may be helpful. Of course, some people may prefer to stop reading altogether rather than use a resource they perceive as embarrassing or too expensive.
Little clinical data exists regarding the number of patients who give up reading, although reading is consistently mentioned as one of the most important vision-related activities.13,14 Thus, giving up reading is likely to have a huge impact on a patient's quality of life.
Balance, Walking and Falling
Another important aspect of daily living that can be affected by glaucoma is balance and walking. Although it may seem counterintuitive, vision is very important to maintaining your balance. For example, try to stand on one foot with your eyes open; then try to stand on one foot with your eyes closed. (The last time I tried I tipped over!) The clinical evidence suggests that lessened visual input as a result of disease may have a similar effect. Studies have examined the connection between glaucoma and balance by looking at how much individuals sway when they're standing still; if you have glaucoma in both eyes, you sway a lot more.15,16
Given this data, it should be no surprise that several studies have found that glaucoma patients fall two to three times as often as individuals without glaucoma. Some of my own glaucoma patients have mentioned to me that they've fallen. Interestingly, every time I've asked whether the fall was caused by vision difficulties, they've said no. The data, however, suggest that their loss of vision is probably playing a contributory role.
Unfortunately, once a patient has reached this level of difficulty, he needs to either restrict his activities or consider a walking aid, which often marks him as an individual with a disability. As always, our main focus must be preventing visual field loss from reaching the point at which disability occurs.
Another thing studies have found is that glaucoma patients complain about difficulty walking when it's either very bright outside or very dimly lit, or when moving from a bright area to a dark area (or vice versa).12,13,17,18 It may be worth asking your patients if they have trouble in these situations, as a way to alert them that their vision is being affected. They may benefit from being conscious of this so they can minimize vision and walking difficulties by compensating for the lighting conditions, and perhaps by allowing extra time or changing their route from one lighting condition to another.
The Big Picture
Given the multiple ways glaucoma may impact your patients' lives, here are a few things to keep in mind:
• Prevention is the name of the game. First, have a clear understanding of what you're trying to prevent, as this will help you make clinical decisions regarding whether—and how aggressively—to treat. For example, a 2- to 3-decibel worsening of the visual field in a patient with normal visual fields will not result in disability, making observation a viable option. However, this amount of worsening in a patient with moderate or severe visual field loss in both eyes will quite possibly result in additional disability. Furthermore, once vision damage has occurred, managing the resultant disability can be very difficult.
• Not everyone is equally affected by vision loss. Loss of visual field is an obstacle, and many factors will affect how well a patient manages it. Someone in his mid-50s will probably have an easier time compensating; he may even be able to function normally. But 10 or 15 years later, when he's 70, the same level of difficulty may be a lot more problematic. Likewise, someone who has other medical problems may be impacted by vision loss much more profoundly than a peer who is generally healthy.
• The fear factor. A diagnosis of glaucoma, by itself, will probably impact a patient's state of mind. Some studies have found that people diagnosed with glaucoma who have almost no loss in visual field and perform tasks as well as healthy individuals, are more likely to complain of symptoms than their healthy counterparts. This suggests that simply giving patients a diagnosis of glaucoma can affect quality of life.
Fear of glaucomatous vision loss also has two beneficial aspects: It can motivate patients to return for follow-up visits, and it makes them more likely to take their meds.
However, you don't want to introduce an unhealthy amount of fear; making the patient miserable is not going to contribute to his well-being. The best approach is to consider the personality of each patient. An anxious patient will probably return no matter what, and inducing too much concern may be counterproductive. On the other hand, some patients are nonchalant about their disease, and may need to be a little more concerned; otherwise they may not do what they need to do to preserve their vision.
• The condition of the better eye is key. The impact of glaucomatous vision loss at the practical level primarily becomes apparent when the less-affected eye begins to deteriorate. Most studies have found that the amount of visual field loss in the better-seeing eye is the most predictive measure with regard to outcomes. So, once glaucoma is affecting both eyes, anything you can do to preserve the patient's visual field in the eye that is healthier can have a very substantial effect on what the patient will remain able to do.
For that reason, I've become more aggressive in treating the better-seeing eye. Primary open-angle glaucoma is really a bilateral condition, even though it often affects one eye earlier or more severely than the other eye. So, if I know that someone has glaucoma in one eye, I don't see much reason to delay treatment for the second eye, especially if that treatment doesn't involve something as risky as surgery.
1. Haymes SA, LeBlanc RP, Nicolela MT, et al. Glaucoma and on-road driving performance. Invest Ophthalmol VisSci 2008;49:3035–3041.
2. Ramulu PY et al. Ophthalmology. Driving Cessation and Driving Limitation in Glaucoma The
3. McGwin G Jr, Owsley C, Ball K. Identifying crash involvement among older drivers: agreement between self-report and state records. Accid Anal Prev 1998;30:781–791.
4. McGwin G Jr, Xie A, Mays A, et al. Visual field defects and the risk of motor vehicle collisions among patients with glaucoma. Invest Ophthalmol Vis Sci 2005;46:4437–4441.
5. Haymes SA, Leblanc RP,
6. Hu PS, Trumble DA, Foley DJ, etal. Crash risks of older drivers: a panel data analysis. Accid Anal Prev 1998;30:569–581.
7. McGwin G Jr, Mays A, Joiner W, et al. Is glaucoma associated with motor vehicle collision involvement and driving avoidance? Invest Ophthalmol Vis Sci 2004;45:3934–3939.
8. Szlyk JP, Taglia DP, Paliga J, etal. Driving performance in patients with mild to moderate glaucomatous clinical vision changes. J Rehabil Res Dev 2002;39:467–482.
9. Freeman EE, Gange SJ, Munoz B, West SK. Driving status and risk of entry into long-term care in older adults. Am J Public Health 2006;96:1254–1259.
10. Viswanathan AC, McNaught AI, Poinoosawmy D, et al. Severity and stability of glaucoma: patient perception compared with objective measurement. Arch Ophthalmol 1999;117:450–454.
11.
12. Nelson P, Aspinall P, O'Brien C. Patients' perception of visual impairment in glaucoma: a pilot study. Br J Ophthalmol 1999;83:546–552.
13. Burr JM, Kilonzo M, Vale L, Ryan M. Developing a preference-based Glaucoma Utility Index using a discrete choice experiment. OptomVis Sci 2007;84:797–808.
14. Aspinall PA, Johnson ZK, Azuara-Blanco A, et al. Evaluation of quality of life and priorities of patients with glaucoma. Invest Ophthalmol Vis Sci 2008;49:1907–1915.
15. Shabana N, Cornilleau-Peres V, Droulez J, et al. Postural stability in primary open-angle glaucoma. Clin Experiment Ophthalmol 2005;33:264–273.
16. Black AA, Wood JM, Lovie-Kitchin JE, Newman BM. Visual impairment and postural sway among older adults with glaucoma. OptomVis Sci 2008;85:489–497.
17. Lee BL, Gutierrez P, Gordon M, etal. The Glaucoma Symptom Scale. A brief index of glaucoma-specific symptoms. Arch Ophthalmol 1998;116:861– 866.
18. Hassan SE, Hicks JC, Lei H, Turano KA. What is the minimum field of view required for efficient navigation? Vision Res 2007;47:2115–2123.
