A group of South Korean and American researchers have investigated the relationship between preferred sleeping position and asymmetric [i.e., not identical in both eyes] visual field loss in subjects with glaucoma. Their results suggest that the sleep position habitually preferred by the study participants [i.e., lying on the same side of the body as the eye with the greater visual field loss] could be a factor that contributes to glaucoma progression.
(Please note: The researchers did not determine that sleep position caused asymmetric field loss; they only determined that sleep position was a factor that required further investigation. For future studies, the researchers also recommend video recording during sleep to supplement questionnaires, in order to collect more precise data.)
The research, entitled Relationship between Preferred Sleeping Position and Asymmetric Visual-field Loss in Open-angle Glaucoma Patients, was published online “ahead of print” on December 16, 2013 in the American Journal of Ophthalmology.
The authors are Kyoung Nam Kim, Jin Wook Jeoung, Ki Ho Park, Dong Myung Kim, and Robert Ritch, who represent the following institutions: Chungnam National University Hospital, Daejeon; Seoul National University Hospital; Seoul National University College of Medicine; New York Eye and Ear Infirmary; and New York Medical College.
About the Body and Sleep Position
The term “decubitus” is commonly used in medicine to mean “lying down.” It is derived from the Latin verb decumbere, or “to lie down.” When medical professionals use the term decubitus to describe the position of a patient, they first state the part of the body on which the patient is resting, followed by the word decubitus. Here are some examples:
- Lateral: on the side
- Right lateral decubitus: lying on the right side
- Left lateral decubitus: lying on the left side
- Supine: Flat on the back or face up
More about the Sleep Position Research
From Study: Sleeping position may worsen glaucoma at Healio medblog:
[Lead author] Kim and colleagues wrote, “During sleep, body position varies between the supine position and the lateral decubitus position, often more on one side than the other. Thus, [intraocular, or within the eye] pressure elevation related to the lateral decubitus position might play a role in glaucoma progression.”
The authors studied 692 patients with bilateral [i.e., both eyes] normal-tension glaucoma or high-tension glaucoma. Participants took a questionnaire to determine their preferred sleeping positions and were labeled with a better eye and worse eye.
The researchers found that of the enrolled participants, [430 subjects or 62.1%] had asymmetric visual field loss between their eyes.
Among the 309 normal-tension glaucoma patients [with asymmetric field loss], 100 preferred to sleep on their side, and 66 of those patients chose to sleep with their worse eye downward.
Among the 121 high-tension glaucoma patients [with asymmetric field loss], 32 preferred to sleep on their side, and 23 of those patients chose to sleep with their worse eye downward.
“Our results suggest that the sleep position habitually preferred by glaucoma patients may be associated with greater visual field loss,” the authors concluded.
High-Tension and Normal-Tension Glaucoma
The term “glaucoma” describes a group of eye diseases that damage the optic nerve. It is one of the leading causes of vision loss and blindness.
Normal-tension glaucoma, also called low-tension glaucoma, is a type of glaucoma in which individuals with the disease experience optic nerve damage and subsequent vision loss, despite having normal intraocular pressure (IOP).
Most eye care professionals define the range of normal IOP as between 10 and 21 mm Hg [i.e., millimeters of mercury, which is a pressure measurement]. Most persons with glaucoma have an IOP measurement of greater than 21 mm Hg; persons with normal-tension glaucoma, however, have an IOP measurement within the normal range.
Here is more information about normal-tension glaucoma from WebMD:
By definition, people with normal-tension glaucoma have open, normal-appearing angles. In fact, the features of normal-tension glaucoma are similar to primary open-angle glaucoma (POAG), the most common form of glaucoma.
Although the occurrence of normal-tension glaucoma varies worldwide, it is very prevalent in Japan. In the United States, up to 15-25% of people with open-angle glaucoma experience normal-tension glaucoma. Normal-tension glaucoma is more common in women than in men, and in adults aged 60+.
Although its cause is not completely understood, normal-tension glaucoma is generally believed to occur either because of an unusually fragile optic nerve that can be damaged despite a normal pressure inside the eye, or because of reduced blood flow to the optic nerve.
A Research Summary from the Journal of Ophthalmology
From Relationship between Preferred Sleeping Position and Asymmetric Visual-field Loss in Open-angle Glaucoma Patients:
Methods: 692 patients with bilateral normal-tension glaucoma or high-tension glaucoma were consecutively enrolled. A questionnaire to determine the preferred sleeping position was administered to each patient. Asymmetric visual field loss was defined as a difference in mean deviation between the two eyes of at least 2 dB. According to these values, the better eye and worse eye were defined. Among the patients with asymmetric visual field loss, the numbers preferring the worse-eye-dependent lateral decubitus position and the better-eye-dependent lateral decubitus position were compared.
Results: Among the enrolled patients, 309 (60.6%) with normal-tension glaucoma and 121 (66.5%) with high-tension glaucoma had asymmetric visual fields between the two eyes.
Among the 309 normal-tension glaucoma patients, 100 (32.4%) preferred the lateral decubitus position. Of these, 66 (66.0%) preferred the worse-eye-dependent lateral decubitus position.
Among the 121 high-tension glaucoma patients, 32 (26.4%) preferred the lateral decubitus position, and of these, 23 (71.9%) preferred the worse-eye-dependent lateral decubitus position.
Conclusion: Our results suggest that the sleep position habitually preferred by glaucoma patients may be associated with greater visual field loss.
More about Glaucoma
January is Glaucoma Awareness Month. Visit VisionAware to learn more about ongoing glaucoma research, including: