Maintaining quality of life is a central goal in glaucoma management, as, for example, expressed in the most recent Guidelines of the European Glaucoma Society: 'The goal of care for people with, or at risk of, glaucoma is to promote their well-being and quality of life within a sustainable health care system.' Odden and co-workers' paper is an ambitious addition to the literature on QoL and functional disabilities in glaucoma. This paper summarizes and extends several separate investigations on this subject that have previously been published by the authors during a period of several years.
The authors have studied the effects of central versus peripheral visual field loss on many functional domains including quality of life (QOL), fear of falling, instrumental activities of daily life, driving, reading speed and gait in 231 patients with glaucoma, or suspected glaucoma associated with ocular hypertension, positive family history, or presence of exfoliation syndrome.
Central threshold visual field testing was performed with the 24-2 SITA Standard test, while the peripheral field was tested with a suprathreshold test including 60 test point locations 30°-60° from fixation. Binocular fields were created and test points were dichotomized as being normal/abnormal.
Data were analyzed using multivariable regression models that were created separately for each disability outcome. Age, gender race, and comorbidities were included as covariates in all models. Disabilities were also evaluated both with either central or peripheral damage only as independent variables, and with central or peripheral damage simultaneously included in the model. Thus, analyses assessed a very large number of relationships.
Central damage was more strongly associated with most disabilities
The results demonstrated that most study participants had mild disease, with a median MD of only -2.31 dB in the better eye and -5.16 dB in the worse eye. Similarly, the mean percentages of abnormal test point locations were only 1.9% in the central field and 5.4% in the peripheral field. Despite this material being composed of mostly patients with mild disease, the authors found many statistically significant relationships. Most importantly the relative importance of central and peripheral field loss differed across functional domains. Central damage was more strongly associated with most disabilities such as fear of falling, QoL, and difficulties with independent activities of daily living. Peripheral field loss, but not central, was associated with gait measures: shorter steps and strides and greater variability in step length. In this cohort, both central and peripheral damage were not significantly associated with maximum reading speed, driving cessation or self-reported driving limitations.
Perhaps importantly, the authors commented that while both peripheral and central regions were important in assessing function, neither contributed a statistically significant amount of additional information when added to original main analyses, and that r2 values were generally low, and not substantially higher for models including both central and peripheral damage.
We commend the authors for their extensive work in this area, extending over many years. This paper is a valuable addition to the sparse literature on the influence of peripheral visual field damage on functional disabilities. Yet, as the authors state, one should be cautious about generalizing their findings to patients having severe glaucomatous damage, since most patients in the authors studies had mild disease.
It seems that some of the weak relationships and lack of statistical significance might have been due to the fact that the glaucoma/suspect glaucoma population examined was a rather healthy one. Repeating some of the authors' studies in a patient population having moderate to severe glaucomatous field loss might be more revealing.
Repeating some of the authors' studies in a patient population having moderate to severe glaucomatous field loss might be more revealing
Relationships between functional disability and glaucomatous field loss would be expected to be stronger, with higher r2-values and findings that are clear-cut. And, perhaps the number of patients material needed might be considerably smaller than that reported in the present paper. The areas researched, and at least partially pioneered by the authors are important, and deserve further study.