Is Vision Loss in IIH Associated With Weight Gain Before Diagnosis?
Surprising Findings From IH Registry Study Published in the Journal of Women's Health
Previous research on women with IIH has suggested that obesity or recent weight gain was associated with a greater risk of sustained vision loss or deterioration of the vision field. The following paper is the second research study published from an IH Registry project.
Previous research on women with IIH has suggested that obesity or recent weight gain was associated with a greater risk of sustained vision loss or deterioration of the vision field. The following paper is the second research study published from an IH Registry project.This study seeks to determine whether a correlation exists between vision loss and weight gain in the year prior to diagnosis. We are pleased to present this paper as an example of the important, new research that the IH Registry is generating, and its impact on our understanding of IH, and finding a cure.
Weight and visual field deficits in women with idiopathic intracranial hypertension
Baldwin MK, Lobb B, Tanne E, Egan R
Journal of Women’s Health, Volume 19, Issue 10
October 2010, pg. 1893-8
1 Department of Obstetrics and Gynecology, Oregon Health &Science University, Portland, OR
2. Intracranial Hypertension Registry, Oregon Health & Science University, Portland, OR.
3. Department of Neuro-Ophthalmology, St. Helena Hospital, St. Helena, CA.
IIH is often characterized by symptoms of elevated intracranial pressure including headache, pulse synchronous tinnitus and transient visual obscurations. Swollen optic nerves (papilledema) are a common finding and if left untreated, can lead to vision loss.
Attempts have been made to identify risk factors for disease severity. Previous, older studies have reported that obesity or recent weight gain was associated with a greater risk of sustained vision loss or deterioration of visual field grade. The purpose of this paper was to investigate the relationship between weight in the year before diagnosis and visual field deficits at diagnosis. The study also assessed the relationship between other weight measures including weight gain, body mass index (BMI) and weight change percentage of ideal bodyweight (IBW), and the presence of abnormal visual field findings at diagnosis; and described the study population’s characteristics.
Materials and Methods
Female study participants who met diagnostic and study criteria were selected from a population of registrants who enrolled in the Intracranial Hypertension Registry (IHR) during the study period of January 1, 2003 through December 31, 2005. A total of 159 study subjects (32% of the total IHR population at that time) met diagnostic criteria for IIH and study eligibility criteria. Study subjects were adolescent girls and adult women with IIH aged 13-65 with documented papilledema and conformed to the Dandy Criteria. To avoid confusing physiological changes caused by pregnancy, women were excluded if they were pregnant at the time of diagnosis.
Registrants reported their current weight and height; they were asked to recall their weight at diagnosis and at one year before diagnosis. Weight change (kg) was calculated as the difference between a registrant’s self-reported weight 1 year prior and weight at diagnosis. IBW (ideal body weight) and weight change as a percentage of IBW was calculated using standard formulas. Additional registrant medical records at the IH Registry were used to collect further data. All patients were required to have either symmetric (both eyes) or asymmetric papilledema (one eye). The visual field examination in the patients’ medical records closest to the date of diagnosis was identified and used in the study.
The study population of 159 females was overall young, predominantly white, educated, and obese. Mean age was 32 (range: 14-64 years old, standard deviation: 10 years). Education level (n=114) evaluation showed 42% had completed college or a higher level education; 95.6% had obtained a high school diploma or higher. 96.9% were adults over the age of 17. Study participants lived in 36 states.
Study patients had a mean weight 1 year before diagnosis of 92 kg (range: 44-218 kg). Nineteen percent (n=27) lost weight in the year before diagnosis, whereas 23% (n=32) gained 3-9 kg and 22% (n=30) gain ~10kg. The year before diagnosis, the mean BMI of the study population was 34.1 kg/m² (range 16.6-70.9 kg/m², 46% (n=66) were obese with a BMI 30-39 kg/m² (2), and 22% (n=32) were morbidly obese with BMI ~ 40kg/m². Study subjects weighed an average of 64% (range: 20-239%) above their IBW.
The majority of study subjects had visual field examinations performed by a neuro-ophthalmologist (67%) or an ophthalmologist (32%). At the examination closest to the date of diagnosis, 84% (n=122) had at least one abnormal visual field finding unilateral or bilaterally. The most common visual field deficits were the presence of an enlarged blind spot (EBS) (50%) or peripheral constriction (40%). Arcuate (curved) or nasal field defects were present in 20% of individuals, central or paracentral deficits in 9%, and inferior or superior altitudinal loss in 8%. Of those with abnormal findings, 46% (n=56) had only one category of deficit, 44% (n=54) had two categories, 7% (n=9) had three categories, and 2% (n=3) had four categories.
No significant correlations were found between weight 1 year before diagnosis and study population characteristics including age at diagnosis, race, region, year of diagnosis, and lumbar puncture opening pressure. There was no significant relationship between the prevalence of higher weight 1 year before diagnosis and abnormal visual field status at the time of diagnosis.
Most patients (95%) reported headache at diagnosis or associated with the disorder. Only 8 reported no headache. A majority (n=11, 69.8%) reported tinnitus and 63% (n=100) reported neck pain or stiffness. Symptoms of abnormal vision were reported in fewer than half of the patients. Of those reporting abnormal vision, abnormal peripheral vision occurred in 77%, central vision was abnormal for either left or right eye in 40% and double vision in 35%.
In this study of women selected from the Intracranial Hypertension Registry population, the authors found no difference in visual fields status at diagnosis for those who gained weight 1 year before diagnosis. This observation is consistent when considering other weight categorizations including BMI and percent change in IBW.
The researchers recognized certain limitations to their study design. For examples, they indicated that there might be selection bias, resulting in an overestimation of severe disease in the study population, including those with worse symptoms and more abnormal visual fields deficits and those who were more obese, because patients with milder disease may not enrolled in the IH Registry. Additionally, recall bias likely affected the data collection particularly in patients who subjectively estimated weight one year prior to diagnosis. Medical records confirmed only those whose medical records were complete within the IH Registry.
The researchers concluded that there was no association between weight 1 year before diagnosis of IIH and the presence of abnormal visual fields findings at the time of diagnosis in an IH Registry population of women with IIH who had a prevalence of abnormal visual field findings of 84% and a mean BMI of 37kg/m² at diagnosis.