Obesity is Only Lifestyle Factor Found to Influence Risk for Glaucoma

Only one lifestyle factor – obesity – was found to influence a patient’s risk for open-angle glaucoma, and it exerted a protective effect in women only, according to a study published Feb. 14 in the Archives of Ophthalmology.

Patient education level, income, smoking status, and alcohol intake all had no association with risk for developing glaucoma, and obesity had no association with glaucoma risk among men, said Dr. Wishal D. Ramdas of the departments of epidemiology and ophthalmology at Erasmus Medical center, Rotterdam, The Netherlands, and associates.

Previous studies of glaucoma risk have yielded conflicting results regarding lifestyle factors. Conclusions about smoking and alcohol intake in particular have been very mixed. Dr. Ramdas and colleagues examined the issue using data from the Rotterdam Study, a prospective population-based cohort study of eye disorders among Netherlands residents who were aged 55 and older when first assessed in 1991-93 and who were followed up in 1997-99 as well as in 2002-2006.

The study subjects’ eyes were examined using autorefraction, keratometry, measurement of visual acuity, tonometry, fundus photography, tomographic imaging, and visual field testing.

For this study, a subset of 3,939 subjects who were free of glaucoma at baseline and were followed for a mean of 10 years were assessed. A total of 108 (2.7%) developed glaucoma during that time.

Overall, the only difference in lifestyle factors between subjects who developed glaucoma and subjects who did not was obesity. Subjects who developed glaucoma had a significantly lower body mass index than did those who did not.

Further analysis showed that this association was present only among women. In women, each unit increase in BMI was associated with a 7% reduction in the risk of developing glaucoma, the investigators said (Arch. Ophthalmol. 2011 Feb. 14 [doi:10.1001/archophthalmol.2010.373]).

There also was no association between glaucoma risk and alcohol intake when the data were broken down according to the percentage of alcohol in various drinks. Subjects who drank beverages with a comparatively low alcohol content (such as beer and wine) showed the same risk of developing glaucoma as did subjects who drank beverages with a moderate alcohol content (such as port wine or sherry) or the strongest alcohol content (such as hard liquor).

The study had one paradoxical finding: BMI was inversely related to intraocular pressure. Higher BMI raised the risk of higher intraocular pressure, which in turn should have raised rather than lowered the risk of developing glaucoma among women.

The reason for this contradiction is not yet known, but given the discrepant results between men and women, it may be related to estrogen levels. Body fat has estrogenic effects, so it’s possible that higher BMI raises intraocular pressure but these estrogenic effects protect against glaucoma, Dr. Ramdas and associates wrote.

They also suggested that the protective effect could be related to an instrument used in the study: “An explanation for this finding is that, with Goldmann applanation tonometry, the thorax and abdomen are pushed against the slitlamp table while breath holding works like a Valsalva maneuver” especially for obese women. This could lead to an overestimation of IOP which may have contributed to this inverse association, they wrote.

Only one lifestyle factor – obesity – was found to influence a patient’s risk for open-angle glaucoma, and it exerted a protective effect in women only, according to a study published Feb. 14 in the Archives of Ophthalmology.

Patient education level, income, smoking status, and alcohol intake all had no association with risk for developing glaucoma, and obesity had no association with glaucoma risk among men, said Dr. Wishal D. Ramdas of the departments of epidemiology and ophthalmology at Erasmus Medical center, Rotterdam, The Netherlands, and associates.

Previous studies of glaucoma risk have yielded conflicting results regarding lifestyle factors. Conclusions about smoking and alcohol intake in particular have been very mixed. Dr. Ramdas and colleagues examined the issue using data from the Rotterdam Study, a prospective population-based cohort study of eye disorders among Netherlands residents who were aged 55 and older when first assessed in 1991-93 and who were followed up in 1997-99 as well as in 2002-2006.

The study subjects’ eyes were examined using autorefraction, keratometry, measurement of visual acuity, tonometry, fundus photography, tomographic imaging, and visual field testing.

For this study, a subset of 3,939 subjects who were free of glaucoma at baseline and were followed for a mean of 10 years were assessed. A total of 108 (2.7%) developed glaucoma during that time.

Overall, the only difference in lifestyle factors between subjects who developed glaucoma and subjects who did not was obesity. Subjects who developed glaucoma had a significantly lower body mass index than did those who did not.

Further analysis showed that this association was present only among women. In women, each unit increase in BMI was associated with a 7% reduction in the risk of developing glaucoma, the investigators said (Arch. Ophthalmol. 2011 Feb. 14 [doi:10.1001/archophthalmol.2010.373]).

There also was no association between glaucoma risk and alcohol intake when the data were broken down according to the percentage of alcohol in various drinks. Subjects who drank beverages with a comparatively low alcohol content (such as beer and wine) showed the same risk of developing glaucoma as did subjects who drank beverages with a moderate alcohol content (such as port wine or sherry) or the strongest alcohol content (such as hard liquor).

The study had one paradoxical finding: BMI was inversely related to intraocular pressure. Higher BMI raised the risk of higher intraocular pressure, which in turn should have raised rather than lowered the risk of developing glaucoma among women.

The reason for this contradiction is not yet known, but given the discrepant results between men and women, it may be related to estrogen levels. Body fat has estrogenic effects, so it’s possible that higher BMI raises intraocular pressure but these estrogenic effects protect against glaucoma, Dr. Ramdas and associates wrote.

They also suggested that the protective effect could be related to an instrument used in the study: “An explanation for this finding is that, with Goldmann applanation tonometry, the thorax and abdomen are pushed against the slitlamp table while breath holding works like a Valsalva maneuver” especially for obese women. This could lead to an overestimation of IOP which may have contributed to this inverse association, they wrote.

Only one lifestyle factor – obesity – was found to influence a patient’s risk for open-angle glaucoma, and it exerted a protective effect in women only, according to a study published Feb. 14 in the Archives of Ophthalmology.

Patient education level, income, smoking status, and alcohol intake all had no association with risk for developing glaucoma, and obesity had no association with glaucoma risk among men, said Dr. Wishal D. Ramdas of the departments of epidemiology and ophthalmology at Erasmus Medical center, Rotterdam, The Netherlands, and associates.

Previous studies of glaucoma risk have yielded conflicting results regarding lifestyle factors. Conclusions about smoking and alcohol intake in particular have been very mixed. Dr. Ramdas and colleagues examined the issue using data from the Rotterdam Study, a prospective population-based cohort study of eye disorders among Netherlands residents who were aged 55 and older when first assessed in 1991-93 and who were followed up in 1997-99 as well as in 2002-2006.

The study subjects’ eyes were examined using autorefraction, keratometry, measurement of visual acuity, tonometry, fundus photography, tomographic imaging, and visual field testing.

For this study, a subset of 3,939 subjects who were free of glaucoma at baseline and were followed for a mean of 10 years were assessed. A total of 108 (2.7%) developed glaucoma during that time.

Overall, the only difference in lifestyle factors between subjects who developed glaucoma and subjects who did not was obesity. Subjects who developed glaucoma had a significantly lower body mass index than did those who did not.

Further analysis showed that this association was present only among women. In women, each unit increase in BMI was associated with a 7% reduction in the risk of developing glaucoma, the investigators said (Arch. Ophthalmol. 2011 Feb. 14 [doi:10.1001/archophthalmol.2010.373]).

There also was no association between glaucoma risk and alcohol intake when the data were broken down according to the percentage of alcohol in various drinks. Subjects who drank beverages with a comparatively low alcohol content (such as beer and wine) showed the same risk of developing glaucoma as did subjects who drank beverages with a moderate alcohol content (such as port wine or sherry) or the strongest alcohol content (such as hard liquor).

The study had one paradoxical finding: BMI was inversely related to intraocular pressure. Higher BMI raised the risk of higher intraocular pressure, which in turn should have raised rather than lowered the risk of developing glaucoma among women.

The reason for this contradiction is not yet known, but given the discrepant results between men and women, it may be related to estrogen levels. Body fat has estrogenic effects, so it’s possible that higher BMI raises intraocular pressure but these estrogenic effects protect against glaucoma, Dr. Ramdas and associates wrote.

They also suggested that the protective effect could be related to an instrument used in the study: “An explanation for this finding is that, with Goldmann applanation tonometry, the thorax and abdomen are pushed against the slitlamp table while breath holding works like a Valsalva maneuver” especially for obese women. This could lead to an overestimation of IOP which may have contributed to this inverse association, they wrote.