A peptide for use in a method of preventing or treating neurotrophic keratitis, consisting of a stabilized sequence of the sequence represented by: HSDGIFTDSYSRYRKQMAVKKYLAAVLGKRYKQRVKNK (SEQ ID NO: 1) or HSDGIFTDSYSRYRKQMAVKKYLAAVL (SEQ ID NO: 2), wherein the peptide consisting of the stabilized sequence has the sequence listed as SEQ ID NO: 1 or 2 with the carboxyl groups of the aspartic acid residues at position 3 and/or position 8 replaced with tetrazole, or its partially modified sequence wherein the partially modified sequence is a sequence wherein amino acids are added to the N-terminal end or C-terminal end, and the peptide consisting of the stabilized sequence has affinity for PAC1R, VPAC1R and/or VPACR2, or wherein the peptide consisting of the stabilized sequence is a peptide with the sequence represented by: H-X 1 -D-G-1-F-T-D-X 2 -Y-X 3 -R-Y-R-X 4 -X 5 -X 6 -A-X 7 -X 8 -X 9 -Y-L-A-A-V-X 10 (SEQ ID NO: 3) {where X 1 is a neutral amino acid, X 2 is a neutral amino acid, X 3 is a neutral amino acid, X 4 is a basic amino acid, X 5 is a neutral amino acid or egTz, X 6 is a non-polar amino acid, X 7 is a non-polar amino acid, X 8 is a basic amino acid, X 9 is a basic amino acid and X 10 is a neutral amino acid}, with the carboxyl groups of the aspartic acid residues at position 3 and/or position 8 replaced by tetrazole, or its modified sequence wherein the modified sequence is a sequence with an addition of one or more amino acids, and/or wherein one or two amino acids are deleted, wherein the peptide has affinity for PAC1R, VPAC1R and/or VPACR2, and the modified sequence is the sequence listed as SEQ ID NO: 3 having a deletion or addition of one or more amino acids. HSDGIFTDSYSRYRKQMAVKKYLAAVLGKRYKQRVKNK (SEQ ID NO: 1) or HSDGIFTDSYSRYRKQMAVKKYLAAVL (SEQ ID NO: 2), wherein the peptide consisting of the stabilized sequence has the sequence listed as SEQ ID NO: 1 or 2 with the carboxyl groups of the aspartic acid residues at position 3 and/or position 8 replaced with tetrazole, or its partially modified sequence wherein the partially modified sequence is a sequence wherein amino acids are added to the N-terminal end or C-terminal end, and the peptide consisting of the stabilized sequence has affinity for PAC1R, VPAC1R and/or VPACR2, or wherein the peptide consisting of the stabilized sequence is a peptide with the sequence represented by: H-X 1 -D-G-1-F-T-D-X 2 -Y-X 3 -R-Y-R-X 4 -X 5 -X 6 -A-X 7 -X 8 -X 9 -Y-L-A-A-V-X 10 (SEQ ID NO: 3) {where X 1 is a neutral amino acid, X 2 is a neutral amino acid, X 3 is a neutral amino acid, X 4 is a basic amino acid, X 5 is a neutral amino acid or egTz, X 6 is a non-polar amino acid, X 7 is a non-polar amino acid, X 8 is a basic amino acid, X 9 is a basic amino acid and X 10 is a neutral amino acid}, with the carboxyl groups of the aspartic acid residues at position 3 and/or position 8 replaced by tetrazole, or its modified sequence wherein the modified sequence is a sequence with an addition of one or more amino acids, and/or wherein one or two amino acids are deleted, wherein the peptide has affinity for PAC1R, VPAC1R and/or VPACR2, and the modified sequence is the sequence listed as SEQ ID NO: 3 having a deletion or addition of one or more amino acids. {where X 1 is a neutral amino acid, X 2 is a neutral amino acid, X 3 is a neutral amino acid, X 4 is a basic amino acid, X 5 is a neutral amino acid or egTz, X 6 is a non-polar amino acid, X 7 is a non-polar amino acid, X 8 is a basic amino acid, X 9 is a basic amino acid and X 10 is a neutral amino acid}, with the carboxyl groups of the aspartic acid residues at position 3 and/or position 8 replaced by tetrazole, or its modified sequence wherein the modified sequence is a sequence with an addition of one or more amino acids, and/or wherein one or two amino acids are deleted, wherein the peptide has affinity for PAC1R, VPAC1R and/or VPACR2, and the modified sequence is the sequence listed as SEQ ID NO: 3 having a deletion or addition of one or more amino acids.