Comparability of proptoi meaurement by different technique

PURPOE: To compare meaurement of proptoi obtained by clinician and computed tomography. DEIGN: Cohort tudy. METHOD: In a propective randomized tudy of orbital radiotherapy for Grave’ ophthalmopathy, meaurement of proptoi were made on the ame viit by an endocrinologit and an ophthalmologit uing the Krahn exophthalmometer and by a technician uing orbital computed tomography (CT) can taken with head fixation to minimize poition artifact. REULT: Both clinical oberver recorded proptoi meaurement that were greater by 0.6 to 1.6 mm than thoe oberved on the CT can. Thi dicrepancy reulted in part from the clinical meaurement being made to the anterior corneal urface, wherea the CT meaurement were made to the poterior corneal urface (a difference of approximately 0.5 mm). The aggregated obervation of the clinician did not vary ignificantly from each other but wide dicrepancie (a much a 5 mm) were noted between ingle meaurement made on the ame patient and on the ame day by different clinician. CONCLUION: The degree of variance oberved in clinical meaurement emphaize the importance of defining reproducibility of the meaurement technique in propective tudie of therapeutic efficacy in patient with Grave’ ophthalmopathy. The ytematic difference between CT and clinical meaurement of proptoi hould be noted when reult of clinical trial are compared.