Dear Editor,I read with interest the article authored by Ahn and colleagues on their experience assessing the effectiveness of hyperbaric oxygen therapy (HBOT) in sudden sensorineural hearing loss.[1] They have concluded that HBOT is not of use in patients with greater than 80-dB loss. This is not consistent with a recent meta-analysis by Rhee, which suggested those with greater loss derive greatest benefit.[2] Additionally, our own outcome data suggest that early intervention improves outcomes when using HBOT.[3]As the data provided in Table 1 did not give the reader information to enable the comparison of groups for a similar duration of hearing loss and time until HBOT was instituted, it is hard to discern if the groups were the same. The hyperbaric protocol was not clearly described (10-20 treatments presumably by clinician discretion and with no treatment endpoints for HBOT given). This means it is difficult to assess the validity of their conclusions as those with the longest period of symptoms may have been differently distributed between groups.Specifically, very little detail was provided in relation to HBOT protocols. Was the treatment given daily, that is, was it given on successive days (weekends) and what determined who received hyperbaric and how many they would receive? Without these details, it is difficult to interpret their results or allow others to replicate the study prospectively.The use of HBOT in this condition is difficult to justify given the continued publication of small retrospective trials and the mixed conclusions this leads to. The Cochrane reviews in this area have repeatedly called for better-designed trials, and it is well overdue that a well-designed trial is performed in this area.[4]I invite the authors to provide further details regarding the timing of HBOT commencement and the protocols in their institution for recommending the addition of HBOT, number, and whether delivered for successive days or only on weekdays.