\pdfcompresslevel=0
\documentclass[tikz,12pt]{standalone}
\usepackage{tikz,pgfplots,pgfplotstable}

\pgfplotsset{compat=1.10}

\begin{document}
\begin{tikzpicture}

\pgfplotsset{every axis/.append style={tick style={line width=0.7pt}}}

\pgfplotstableread{
a b
-0.1 0.2
0.1 0.5
}\testdata

\begin{axis}[axis lines=center, ymin=-0.22,ymax=0.22, xmin=-0.2,xmax=0.2,xlabel=x  ]
    \addplot3 [color=blue,] table[x expr=0,y=a,z=b] {\testdata};
\end{axis}

\end{tikzpicture} 

\end{document}
