My case (a 25yr/F, unmarried lady, squint since birth, BCVA 6/6 either eye) has 30pd XT, 15pd DVD (for distance) and 5pd XT, 15pd DVD (for near) with not much of IOOA. One (male) of my earlier DVD cases had quite some amount of UL ptosis after FADEN (unilateral). This time I want to avoid this problem and intend to go for ATIO or SR Rc.

I think, I have to go for bilateral SR Recession! In that case what should be the amount in each eye? Can it be equal in both eyes? But if asymmetric, how to divide the amount of SR Rc in the two eyes? Please let me know the criteria of dividing the amount of recession in two eyes."

Inferior oblique anterior transposition (IOAT) can be done for all cases of DVD and should be successful in controlling the DVD. The reason that it is usually only done in cases with IO overaction, is that it runs the risk of resulting in post op SOOA with an A pattern, if the IO's are not overacting pre op. Regarding the formula for SR recession, it depends on if surgery is needed bilaterally or unilaterally. In general, DVD is usually bilateral but often asymmetric. Most patients have an intermittently manifest DVD in the non-dominant eye, and a latent DVD (it only goes up under cover) in the dominant eye. Usually, but not always, the eye with the manifest DVD has a larger magnitude of the DVD than the eye with the latent DVD. There are some patients, however, in whom either eye goes up spontaneously on its own. If vision is not equal due to residual amblyopia, one can do unilateral surgery in the amblyopic eye, without fear of them switching fixation, even if the dominant eye goes up under cover. In that situation, I use a surgical formula of 5mm for up to 10 pd, 6mm for 11-15, 7mm for 16-20, 8mm for 21-25, and 9mm more than 25. If vision is equal, you should do bilateral surgery, as they may shift fixation. However in that situation, the surgery done in the habitually fixing eye will somewhat negate the effect of the surgery in the other eye, as the patient will be innervating upgaze to fixate in primary, due to the SR recession. In that case, I add 2 mm to the above formula, with the amount done in each eye based on the amount that eye goes up in the dissociated (occluded) state, and have a maximum of 10mm. For your patient, you did not say how much each eye goes up, and I do not know if the DVD is 15 for each eye. If so, I suggest 8mm in each eye.