Abstract
Purpose: :
To evaluate the effectiveness of L-arginine for the treatment of r-NAION using the optical coherent tomography (OCT). L-arginine, a NO substrate, is a non-toxic amino acid and it has been known to be clinically useful as a growth hormone releasing agent in pediatrics. It is the precursor of the synthesis of Nitric Oxide (NO), a labile free radical, by NO synthese. It has been reported that infusion of L-arginine has produced NO in the rabbit eye and have made the ciliary artery dilate. Thus, L-arginine could have a potential role to improve the optic disc edema efficiently and reduce the following neuronal damage.
Methods: :
To compare the effectiveness of L-arginine for the degree of disc swelling with rNAION control (no treatment, n=7), L-Arginine (500mg/kg, twice a day) was administered intravenously for 7days to the rNAION (n=7), and we measured the inner retinal thickness (from the internal limiting membrane to the inner plexiform layer) using OCT. The OCT was measured before and after the induction at 1st, 3rd, 7th, 14th, 28th, and 56th day.
Results: :
In the L-arginine treatment group, the degree of disc swelling was significantly smaller than the control group at 1st and 3rd day (arginine vs control; 116.32±9.74 (SD) vs 122.34±8.09μm, 108.82±5.47 vs 116.27±8.67, respectively, p<0.05). In the L-arginine treatment group, the preservation of inner retinal thickness was significantly larger than the control group at 7th and 14th day (arginine vs control; 98.55±6.96 (SD) vs 91.20±4.58μm, 76.87±7.78 vs 71.38 ±7.60, respectively, p<0.05). However, the late stage inner retinal thickness was similar in both group at 28thand 56th day (arginine vs control; 65.53±5.63 (SD) vs 65.95±2.78μm, 62.04±7.69 vs 60.15±6.67, respectively, p=0.32,p=0.21 ).
Conclusions: :
In the treatment of L-arginine, the disc swelling of rNAION become milder and slower to reduce the inner retinal thickness. L-arginine does not have the protective effect for the long-standing decrease of inner retinal thickness.
Keywords: neuro-ophthalmology: optic nerve • ischemia • nerve fiber layer