The present invention relates to an apparatus and method for using the apparatus for injecting an agent into a tissue, particularly into thin tissues such as the sclera of the eye. The invention provides an apparatus and method for effectively imbedding a needle into a tissue at a predetermined penetration approach angle and penetration distance thereby reducing the risk of penetrating the full thickness of the tissue. The invention includes a support element and a needle guide platform disposed on the support element with an external support surface and a channel extending therethrough and terminating in an aperture at the support surface. A needle disposed in the channel is axially movable along an axis of injection through the channel. The needle is movable from a first retracted position to an extended position corresponding to the penetration distance, along the axis of injection. The axis of injection forms a penetration approach angle of up to about 60.degree. with a tangent of the support surface at a point of intersection of the axis of injection with the projection of the support surface across the aperture.