A Pilot Randomized Clinical Trial of Base-in 8 Prism Spectacles for Intermittent Exotropia

A Pilot Randomized Clinical Trial of Base-in 8 Prism Spectacles for Intermittent Exotropia To evaluate the initial response to prism spectacles, this 8-week pilot randomized clinical trial 343 (RCT) is proposed. If a reasonable initial response without significant adverse effects is found, a 344 subsequent full-scale RCT would evaluate the long-term effectiveness of prism (e.g., over 1 345 year) and then evaluate the subsequent effectiveness of maintaining control after the prism 346 treatment has been discontinued (e.g., 6 months after discontinuation of prism). This approach 347 was successfully used previously to explore overminus spectacles as a treatment for IXT through 348 an 8-week pilot RCT (IXT3), followed by a full-scale longer RCT to evaluate the long-term 349 effectiveness on treatment and after discontinuation of treatment (IXT5). The objective of this short-term, pilot randomized trial comparing spectacles with relieving prism to spectacles without prism is to determine whether to proceed to a full-scale, longer-term randomized trial. This decision will be based primarily on assessing the initial (8-week) response to prism by comparing treatment groups on the following outcomes: „h Mean distance IXT control score (the mean of 3 control scores) (primary outcome) „h The proportion of participants demonstrating a ¡§treatment response,¡¨ defined as .1 point improvement in the mean distance IXT control score without spontaneous exotropia during 359 control testing (secondary outcome) 360 „h The proportion of participants reporting adverse effects and good/excellent spectacle wear compliance