Effects of Primary Open-angle Glaucoma on Visual-motor Coordination

Commonly used visual function assessments in glaucoma diagnosis and treatment-such as visual acuity, visual field, and contrast sensitivity-do not directly capture the impact of the disease on patients' daily abilities. While questionnaires can evaluate this impact from the patient's perspective, they are subject to individual biases and inconsistent evaluation standards. Thus, objective methods are needed to assess patients' abilities in visually guided daily activities. Grasping objects and avoiding obstacles are fundamental visually guided tasks that require effective visuomotor coordination. By attaching lightweight reflective markers to participants' limbs and using a motion capture system to track their movements in three-dimensional space, various indicators of planning, execution, and control in tasks such as object grasping and obstacle avoidance can be quantified, allowing for an objective evaluation of visuomotor coordination. However, it remains unclear how visuomotor coordination is affected in glaucoma patients at different disease stages or whether visual field damage in specific areas has distinct impacts on visuomotor coordination. This study, therefore, aims to investigate changes in visuomotor coordination among patients with primary open-angle glaucoma across disease stages and to determine the effects of visual field defects in different locations on their visuomotor abilities.

Glaucoma is the leading cause of irreversible blindness worldwide, with an estimated 110 million glaucoma patients expected globally among individuals aged 40-80 by 2040. As a chronic and progressive eye disease, glaucoma can cause significant impairments in visual function. These impairments can severely limit daily activities like searching, walking, and reading, leading to a significant decline in patients' vision-related quality of life. Evaluating the visual abilities of glaucoma patients can not only gauge the extent of the disease's impact on their visual function but also indicate the effectiveness of clinical treatments and rehabilitation strategies. However, commonly used clinical tests, such as visual acuity and visual field, only partially reflect visual function and do not directly measure the disease's impact on daily activities. Questionnaires can be designed to assess the impact of the disease on daily activities, from the patient's perspective. However, as a subjective assessment method, questionnaires are susceptible to individual biases and evaluation standards. Therefore, more objective methods are needed to evaluate patients' performance and abilities in executing daily visually guided activities.

Grasping objects and avoiding obstacles are fundamental visually guided activities that require good visuomotor coordination. The visual system supplies essential information about the spatial position and intrinsic properties of objects, while the brain integrates this information to guide and control limb movements for specific tasks. By attaching lightweight reflective markers, such as spheres or patches, to participants' limbs and using a motion capture system to track these markers in three-dimensional space, various indicators of planning, execution, and control during tasks can be quantified. This approach enables an objective assessment of participants' visuomotor coordination abilities.

Previous studies have shown that glaucoma patients differ from age-matched healthy controls in reaching-grasping tasks, though findings on these differences have been inconsistent. Furthermore, researchers have reported that glaucoma patients also face challenges with mobility. However, it remains unclear how visuomotor coordination in glaucoma patients is affected across different disease stages during tasks like object grasping and obstacle avoidance, or whether the location of visual field damage has varied effects on their visuomotor coordination. In this study, we aim to compare the performance of patients with primary open-angle glaucoma and age-matched healthy controls in reaching-grasping and mobility tasks. Our goal is to investigate changes in visuomotor coordination across different stages of the disease and to clarify how visual field defects in various locations impact patients' visuomotor abilities.

Eligibility Criteria:
Inclusion Criteria:

1.1 Inclusion criteria of primary open-angle glaucoma group:

1. Age between 18 and 75 years;
2. Diagnosed with primary open-angle glaucoma, with no anti-glaucoma surgery scheduled within ±1 month;
3. Best corrected visual acuity in one eye ≥ 6/12;
4. Stereoscopic vision ≥ 1000 seconds of arc;
5. Able to clearly communicate and cooperate with the completion of relevant assessments and data collection.

1.2 Inclusion criteria of healthy controls：

1. Age between 18 and 75 years;
2. No history of eye disease other than refractive error and cataract;
3. Best corrected visual acuity in both eyes ≥ 6/12;
4. Stereoscopic vision ≥ 1000 seconds of arc;
5. Able to clearly communicate and cooperate with the completion of relevant assessments and data collection.

Exclusion Criteria:

1.1 Exclusion criteria for primary open-angle glaucoma group:

1. Individuals with cognitive dysfunction, psychological dysfunction, hearing impairment, or other conditions that prevent normal communication;
2. Presence of physical motor dysfunction, hyperthyroidism or hypothyroidism, malignant tumors, heart disease, or other systemic diseases;
3. Presence of other ocular conditions affecting visual function (except cataract and refractive error), such as age-related macular degeneration, diabetic retinopathy, optic neuropathy, retinal vascular disease, etc.;
4. Pregnant or lactating women.

1.2 Exclusion criteria for healthy controls：

1. Individuals with cognitive dysfunction, psychological dysfunction, hearing impairment, or other conditions that prevent normal communication;
2. Presence of physical motor dysfunction, hyperthyroidism or hypothyroidism, malignant tumors, heart disease, or other systemic diseases;
3. Presence of other ocular conditions affecting visual function (except cataract and refractive error), such as age-related macular degeneration, diabetic retinopathy, optic neuropathy, retinal vascular disease, etc.;
4. Pregnant or lactating women.