Reliability of Hertel Exophthalmometer Measurements

Aim 1. In order to determine intrauser reliability of the Hertel exophthalmometer, patients will have 2 independent exams using the Hertel exophthalmometer on the same day performed by each of the same researcher (either DAC or HLP) in a blinded fashion. For each patient, we will independently measure the base value and the values for the right and left eye proptosis, respectively, using the same Hertel exophthalmometer. A randomization process will be employed to determine which researcher (either DAC or HLP) will take the first set of measurements. The distance of the observer from the patient will be standardized for all measurements. Patient research data will be de-identified and recorded for each patient and subsequently analyzed for interobserver reliability. Aim 2. In order to determine interuser reliability of the Hertel exophthalmometer, patients will have a second independent exam on the same day by the second observer as determined for Aim 1 above. For each patient, we will independently measure the base value and the values for the right and left eye proptosis, respectively, using the same Hertel exophthalmometer. The distance of the observer from the patient will be standardized for all measurements. Patient research data will be de-identified and recorded for each patient and subsequently analyzed for interobserver reliability. Aim 3. Variability in Hertel measurements may be related in large part to differences in the base measurement. The base measurement is determined by the bony orbital structures and should not be significantly affected over time by the soft tissue remodeling commonly seen in TED and most other orbital disease processes. We will have the second observer re-measure the same patient using the same Hertel exophthalmometer by beginning with the same base measurement determined by the first observer. Again, all measurement distances will be standardized. No other information will be provided to the second observer other than the beginning base measurement. Patient research data will again be de-identified prior to recording the information and subsequently analyzed to determine if beginning with the same base improves interobserver reliability.