Sir,

I read with interest the article by Mowatt et al1 describing the correlation of visual recovery with macular height in macular-off retinal detachments. The authors concluded that the shallower the macular detachment, the greater the likelihood of a good visual outcome, and that assessment of pre-operative macular height with B-scan ultrasound can be useful as a predictive factor of final visual outcome for macular-off retinal detachments. Although the study is simple and concise, I have the following comments and questions.

For an objective measurement of the height of macular detachment, I think that the authors should have presented a more detailed method for their ultrasound study. First, the authors did not describe the method used for measuring the height of the movable detached retina after position change (sitting or supine position). Second, the authors should present a reliable and definite check point instead of a vague point, which was described by the authors as ‘a single point on the retinal pigment epithelium, 4 mm temporal from the center of the optic nerve’. In addition, standardization of positions of the ultrasound probe and the examined eyeball is needed for a precise study.

As cited by the authors, Ross et al2 showed that the height of macular detachment is the most important preoperative variable influencing recovery of good central vision in macular-off detachments of ⩽7 days’ duration. However, Ross et al used three-dimensional B-scan ultrasonography to define the full extent of the detachment and to accurately locate the centre of the optic nerve and macular region. I am wondering how to make an accurate measurement of the height of the macular detachment using only two-dimensional B-scan ultrasonography.

I agree that assessment of pre-operative macular height using B-scan ultrasonography is a predictive factor of the final visual outcome for macular-off retinal detachments, and B-scan ultrasonography, the standard equipment used in most ophthalmic departments, could be used for assessment of the height of the macular detachment. However, the authors need to present a simpler and more reliable method for clinical application of their suggestion.