Problem of the present invention is to provide a kind of protective agent that shows effectiveness, the retina neural that can take for a long time or optic nerve with the mechanism different with existing curative.The protective agent of retina neural of the present invention or optic nerve will have the chemical compound shown in for example above-mentioned general formula of the inhibiting chemical compound of aldose reductase as effective ingredient.As chemical compound, preferred (2S, 4S)-6-fluoro-2 , 5 -the dioxo spiral shell [chromane-4,4 -imidazolidine]-the 2-Methanamide.In the formula, X represents halogen atom or hydrogen atom R 1, R 2Represent independently that respectively hydrogen atom maybe can have substituent C1~6 alkyl, perhaps represents R 1, R 2And and R 1, R 2The nitrogen-atoms that connects is together or again with other nitrogen-atoms or 5~6 yuan heterocycle forming of oxygen atom.
