the numeral 10 designates an eyeball in the figures . the eyeball 10 comprises a cornea 11 on its front side and a sclera 12 at the remaining surface . the musculus rectus superior is shown in fig1 at the front of the eyeball 10 . four quadrants are drawn with dot dashed lines 14 on the surface of the eyeball 10 . the outer , upper quadrant 15 is of interest here . the limbus corneae , i . e . the edge region of the cornea 11 is indicated in fig1 with the numeral 16 . fig4 shows the lens as well as the vitreous humor of the eye , behind which the retina 19 is located . in conventional operations in the subretinal region , access is made through the vitreous humor 18 and through the retina 19 . according to the present invention , however , a sclera incision 20 is made in the outer , upper quadrant 15 as clearly shown is fig1 . the sclera incision 20 is rectangular , namely at a distance a of preferably 7 to 8 mm from the limbus . the sclera incision 20 produces the sclera flap 21 with a width b and a length c , which is preferably 4 by 4 mm in size . the chorioidea becomes visible beneath the flap 21 . as seen in the enlarged fig2 and 3 , an incision 25 is now made through the chorioidea 22 , preferably parallel to the chorioideal vessels 23 . the incision 25 has a width d of preferably 2 . 5 to 3 . 5 mm . the foil strip 30 can now be passed through the incision 25 , which has a somewhat smaller width e of for example 2 mm . in addition , the foil strip 30 has a length 1 of preferably 25 mm and a thickness x of only 50 μm . it is rounded at its front end 31 . the foil strip 30 can be provided with a scale 32 to allow a direct reading of depth at which the strip 30 is inserted into the incision 25 . the surface 33 of the strip 30 serves as a guiding surface which will be explained more fully below . as can be seen from the cross - section in fig4 the foil strip 30 has been inserted through the sclera incision 20 and the incision 25 of the chorioidea 22 and into the subretinal region 36 . an implant , for example a multiphotodiode array 40 can now be inserted into the subretinal region 36 with a slider 41 ( fig3 ). a plastic tube is preferably employed as the slider 41 . the slider 41 can also be provided with a scale . the direction of sliding is indicated with 42 in fig3 . with the above - described means , a so - called “ ab externo ” implantation of an implant can be carried out as follows : after cutting through the conjectiva and preparation of the bulbus wall in the outer upper quadrant 15 , the musculus rectus superior 13 and the lateralis are employed as anchoring means . at a distance a of 8 mm from the limbus 16 , a sclera flap 21 is prepared temporally with an edge length of 4 mm . depending on the experience of the operator and the accessibility of the operation area , the sclera incision 20 can be reduced to a length of 6 mm in the assumed direction of the chorioideal vessels 23 . the intraocular pressure is reduced by a paracentese , so that the chorioidea 22 is no longer bulged in the region of the sclera flap 21 . to achieve a local vascular constriction , a drop of ornipressin ( dilution 0 . 5 i . e ./ ml ) is applied to the chorioidea 22 . the chorioidea 22 is then cut at a length d of 2 mm along the direction of the large vessels 23 . the foil strip 30 , preferably of 2 mm width and rounded at its front end , is placed on the neurosensor - containing retina 19 , drawn back to the edge of the chorioidectomy , and then pushed into the subretinal region 36 . the implant , namely a microphotodiode chip 40 , is placed on the strip 30 and inserted into the subretinal region 36 along the strip 30 . the subretinal position of the chip 40 can be derived from the implantation direction along the foil strip 30 and the length of the inserted foil , without direct intraocular observance . the foil is then withdrawn from the subretinal region 36 to protect the retina 19 and the chorioidea 22 and to avoid retina incarceration in the incision area , however is left on the retina 19 and chorioidea 22 while the stitches in the sclera are made . in the described operation , a direct , transscleral , transchoroidal access to the subretinal region is possible without opening the intraocular region . in this manner , operation risks of vitrectomy and retinotomy are substantially avoided , in particular a cataract , an ablatio and pvr . the access obtained by the present invention into the subretinal region can also be employed in other clinical situations , for example in subretinal neovascularisation , bleeding and membranes , implantations and explantations of microphotodiode chips , transplantations of pigment epithelium and retina tissue as well as the subretinal application of drugs . a precise placement of the chip or drugs or micro instruments ab externo at a defined position in the subretinal region is made possible in this manner without direct intraocular observance . in another clinical application of the external access described above , a micro - endoscope of for example 0 . 9 mm diameter , including flushing channel and the option of an integrated laser or micro - gripper , can be introduced into the subretinal region on the foil . with a reduced flushing with saline solution , a fiber optic resolution ( 6 , 000 pixel ) of the chip in the subretinal region is possible . one can for example determine the precise position of the chip , optionally exchange the chip or undertake other micro - surgical procedures under control of the subretinal endoscope , when the micro instruments are integrated into the endoscope such as cutting means , gripping means or a laser .
an operation kit is provided for access into the subretinal region of the eye . the kit comprises an elongated flat body of soft material , which can be inserted into the subretinal region from the side through an incision in the sclera . the body is formed as a strip , whose one surface is configured as a guiding surface for a medical device , for example for implanting a microphotodiode chip .