Intraocular pressure changes with relation to slit lamp neck positioning, breath holding, and weight lifting: a practical approach
The study design will be a prospective study of healthy volunteers between the ages of 20 and 40 to evaluate the difference in IOP under 4 clinically relevant scenarios: forward neck extension in a slit lamp; breath holding in a neutral and forward neck extension weight lifting. This data will be used to understand possible variations in IOP during clinical measurements, to assist patients with breathing techniques or positioning as necessary to avoid incorrect measurements, and to provide an understanding for post operative activity restrictions.
Subjects will be evaluated for pre-existing glaucomatous changes with baseline measurements of IOP, Humphrey Visual Field (HVF) 24-2, and Optical Coherence Tomography (OCT) images of the retina nerve fiber layer in both eyes. Qualifying subjects will undergo intraocular pressure measurements via pneumotonometry under 5 conditions: sitting upright neck neutral normal breathing, sitting forward with neck extended in a slit lamp with normal breathing, sitting upright neck neutral with breath holding for 10 seconds, and sitting upright neck neutral normal breathing lifting and releasing two 10 lb weights (one for each arm).. Each scenario will be analyzed against the first position with a T-test to compare each group. We will aim to recruit 25 qualifying subjects to have statistically relevant data. Only 1 person will take intraocular pressure measurements. Although a Goldmann applanation tonometer is considered gold standard, a pneumatonometer will be used in this study to minimize operator variability. Since previous data has shown that successive IOP measurements result in lower measurements, subjects will be asked to wait 5 minutes in between each scenario.
All healthy volunteers between the ages of 20-40 without previous medical or ophthalmologic conditions. Refractive error will not disqualify subjects unless this condition interferes with glaucoma testing, such as OCT analysis.