Promoting effect of n‐decylmethyl sulfoxide on the penetrability of the optic nerve for lidocaine HCI in cats

We examined the effect of n‐decylmethyl sulfoxide (n‐decyIMSO) on the resistance of the optic nerve sheath to the penetration of lidocaine hydrochloride. Three series of experiments were carried out in living cats, administering lidocaine with and without n‐decyIMSO. The visual evoked potential (VEP) and optic nerve response (ONR) were measured. The results obtained indicated that n‐decyIMSO increased the penetration of lidocaine. The presence of lidocaine (1%) and n‐decyIMSO (2.5%) decreased the ONR amplitude from 120 to 15 μV after a time lag of 105 min, and VEP decreased from 9.0 to 5.5 μV. This effect was preserved during the experiment. Histological examination showed only minimal changes in the optic nerve and the eye globe and its contents. Some infiltration of mononuclear cells was found around the optic nerve sheath.