How is the quality of life of glaucoma patients affected in the various disease stages?
João Filipe, MD
In recent decades, medicine has abandoned a more traditional approach to focus on patients and their health and disease prospects. In this context, self-reported quality of life (QL) has been gaining strength, especially in chronic diseases such as glaucoma. Components of good QL differ among individuals and societies; however, sight has been consistently shown to be one of the most determining factors1.
In glaucoma, repercussions on QL are associated significantly with disease severity and there is a trend of increasingly poorer quality of life with disease progression2. the diagnosis itself, functional loss [visual acuity (VA) and visual field], treatment inconveniences, therapy side effects and associated costs3. The impact of glaucoma affects both the ability to perform in daily life activities, such as driving, but also at psychological and social levels4.
In its early stages, glaucomatous damage is relatively asymptomatic due to sensory system redundancy and the binocular nature of vision, where one eye is able to compensate another eye's early losses4. However, the patient's QL may be affected right from the start5, although we ophthalmologists often undervalue this. As highlighted in a recent review study1, we should remember that patients with early or suspected glaucoma are not initially interested in their intraocular pressure, their visual field or excavation, but in aspects that have an impact on their quality of life, namely how comfortable they feel. Indeed, it is estimated that more than 80% of glaucoma patients report anxiety, depression and fear of blindness at onset6. Moreover, topical therapy has an associated discomfort – either due to the need for daily application7, or because of potential symptoms of anterior segment syndrome8. It is recognized that eye drops containing preservatives, especially when used chronically, reduce the stability of lacrimal film and have a direct toxic effect9,10. Therefore, eye drops contribute to the deterioration of anterior segment symptoms and also to lower therapy compliance11. There is an association between eye drop side effects and lower patient-reported QL11. The need for periodic visits is also mentioned as factor for poorer QL. Surprisingly, in spite of this, a prospective study of the Early Manifest Glaucoma Trial12 did not show significant differences in QL as assessed by the VFQ-25 questionnaire (25-item National Eye Institute Visual Function Questionnaire) among patients who initiated and did not initiate anti-glaucoma therapy in early disease stages. Only one poorer VA and poorer mean deviation (MD) in visual field showed a significant association. In fact, although VA loss at this stage is usually early and incipient, it was also significantly related to worse patient-reported QL, even in monocular loss4.
With disease progression, repercussions on QL increase. According to several published studies, VA and visual field loss are the main determinants13, and both factors have an independent impact14. Regarding VA loss, it is worth noting that Freeman et al.15 showed that the impact is several times higher in bilateral VA loss. Patients with bilateral glaucoma show consistently, significantly lower scores. In terms of progressive visual reduction, an American population-based study14 showed that even small losses were associated with poorer QL, whereas deteriorating QL was associated with visual field loss in a linear manner. Also, bilateral losses had an additive effect. In this study, the tasks most affected by visual field loss were mobility and the ability to maintain autonomy. General health was the least affected of the scales assessed. Similar results were reported in the Rotterdam study16 and by Noe et al.17, who reported that over 25% of the patients had moderate to severe mobility restrictions due to visual field loss. However, it is worth noting that although visual field restrictions affect QL regardless of VA, the latter seems to have more impact on patient-reported outcomes14.
In practical terms, VA and visual field loss influence all daily life activities, such as walking, driving, reading, seeing objects upon approach, performing household chores, and others4. Even with preserved central vision, patients may experience difficulties in reading, adapting to light changes and in activities that depend on peripheral vision or contrast perception, such as avoiding obstacles in dark places1. Moreover, these losses are frequently associated with other serious consequences, such as falls and road accidents18. A prospective study19 reported that when compared with a control group with similar general medical conditions, glaucoma patients had a three times greater probability of having had a fall in the past 12 months and 6 times higher of having been involved in a motor vehicle collision in the past 5 years. The population based study Blue Mountains Eye Study20 also reported that reduced visual field was significantly associated with two or more falls in the past 2 months and increased probability of hip fracture. Glaucoma also has consequences on walking speed, balance and daily physical activity13. Naturally, the reduction in physical activity also has consequences on patient global health, namely on cardiovascular risk.
Psychological consequences should also be highlighted. A cross-over study showed that the prevalence of depression rose with increased glaucoma severity, and is more common in elderly people with advanced glaucoma treated with various eye drops21. In terms of fear of blindness, a randomized prospective study22 showed that after initial diagnosis, 34% of the patients reported fear of blindness, and that although this percentage decreased with time, after 5 years almost 50% maintained at least some fear of going blind. Younger subjects with poorer visual acuity and visual field were those who reported most fear. According to the authors, the reasons for high initial fear are unknown: could it be because of the way the diagnosis is imparted or not explaining that, with adequate treatment, the probability of going blind is low? The decrease in fear with time is probably due to regular follow-up and increased knowledge of a low risk of blindness with treatment, as well as progressive adaptation to diagnosis.
In terminal glaucoma stages, the visual field is generally confined to a central fixation island. Unlike early stages, in which VA and visual field of the worst eye are the main determinants of QL, the main impacting eye seems to be the best functioning eye18. As explained, the peak QL loss in each situation discussed above is reached at this stage2.
As for treatment using surgical approaches, the Collaborative Initial Glaucoma Treatment Study (CIGTS)23 showed that they were associated with fewer frequent symptoms and less discomfort, but not to less patient satisfaction nor to lower generic or vision-specific QL scores. In the CIGTS, patients in early disease stages reported difficulties in adapting to light extremes23. Interestingly, medical therapy compliance is estimated to be higher in advanced than in early stages. The potential explanation may be the fact that patients have some perception of diminished visual acuity and are thus more motivated. However, it is believed that these are patients who have greater difficulties with eye drop self-administration24.
In this context, our group has recently developed a prospective observational study to objectively assess (e.g., using video recording) the difficulty of advanced-glaucoma patients in applying their eye drops. Twenty-five patients were included in this study. According to the survey, 68% of these patients reported never having had difficulties in applying their eye drops, but image analysis showed that 20% were unable to apply them and only 40% could do so correctly. Similarly, 72% reported that the bottle never contacted the eye, but this in fact occurred in 40%. In addition, we also assessed the difficulty in performing everyday tasks (wandering through spaces with obstacles, walking on an irregular floor and going up and down stairs) and noted a trend to correlation between visual field defects and task limitation, although it was not statistically significant. Some patients used proprioceptive adaptation mechanisms (e.g. using the foot to locate a step) to overcome limitations in tested activities. This study points out how patients often have a poor perception of their disease-related limitations, and therefore physicians should confirm whether eye drops are properly applied and inform patients of the care they must exercise in their daily activities.
The potential tools to assess QL in glaucoma are outside the scope of this question. Several tools are available25,1. The most common are the NEI-VFQ (The National Eye Institute Visual Function Questionnaire), the NEI-VFQ-25 (25-item National Eye Institute Visual Function Questionnaire), the GQL-15 (The Glaucoma Quality of Life-15) and the SIG (Symptom Impact Glaucoma Score). In the daily medical setting, a careful clinical history is more relevant than all these methods and essential to assess the patient's QL, knowing their potential limitations in daily life activities1. Besides the so-called conventional goals, one major objective of glaucoma treatment should be to preserve the patient's ability to live independently and perform their tasks, so that vision contributes rather than significantly hinders quality of life.