RETINAL TACK AND METHOD FOR IMPLANTING SAME

Abstract: The retinal tack (36) includes a generally conical sharply pointed forward end portion (52) for piercing through the retina (46), choroid (48), and sclera (50). An elongated, generally cylindrical retaining portion has a longitudinal dimension approximating the thickness of a patient's retina (46), choroid (48), and sclera (50) and includes one or more peripheral grooves (58) for receiving sclera tissue displaced during insertion of the forward end portion (52). An enlarged head has a radially extending flange portion (70) for engaging the retina (46) in the area of the opening formed in the retina (46). The tack (36) is carried in the tip (35) of a tubular probe (26) selectively connected in fluid communication with sources of negative and positive pressures. The head (56) includes a seat portion which sealingly engages a complementary seat in the probe tip (35) when a negative pressure is applied to the probe (26). The probe (26) is inserted into the vitreous cavity (44) through an opening in the eyeball (40) and the tack (36) is manually pushed through the retina (46), choroid (48), and sclera (50) until the head (56) engages the retina (46) and the retina (46) is moved against the choroid (48). After a small positive pressure is introduced into the probe (26), it is moved away from the tack (36) and withdrawn from the vitreous cavity (44).

Description: -/ - RETINAL TACK AND METHOD FOR IMPLANTING SAME BACKGROUND OF THE INVENTION This invention relates to ophthalmological corrective surgery and, more particularly, to devices and methods for reattaching a detached retina. Various techniques have been proposed for reattaching a detached retina to the choroid. One approach involves injecting a silicone oil or a gas into the vitreous cavity of the eye. Some question remains with respect to the safety of intravitreous silicone oil and gas injection requires the patient to remain prone. Another approach involves the use of one or more sutures. This approach can be hazardous and, therefore, has not been widely accepted. A further approach involves the use of a retinal tack which is held with a mechanical device, such as intraocular forceps, and inserted through the retina into the choroid and sclera. American journal of Ophthalmology, Vol 95, No. 2, p. 260 (February 1983) describes a plastic tack including a relatively short barb, a tapered section behind the barb, and a relatively long and massive head including slots to facilitate grasping by the forceps. This retinal tack has been found to have a tendency to "pop out" of the sclera within a relatively short time after surgery and, therefore, is not being widely used. Retinal tacks including several barbs have been proposed. While retention is improved somewhat, such tacks are difficult to remove in the event of a retinal tear. SUMMARY OF THE INVENTION One of tne objects of tne invention is to provide a retinal tack wniσn has improved retention cnaraσteristics and can be conveniently inserted througn the retina, choroid, and sclera. Anotner object of tne invention is to provide 3ucn a retinal tack which can be removed witn minimal trauma to tne sclera and cnoroid in tne event of a retinal tear. A furtner object of tne invention is to provide a etnod for conveniently implanting a retinal tack for reattacning a detached retina to tne choroid. Otner oDjects, aspects and advantages of tne invention will Become apparent to tnose skilled in the art upon reviewing tne following detailed description, tne drawing and tne appended claims. The invention provides a retinal tack including a pointed forward end portion for piercing througn the retina, cnoroid, and sclera, an elongated retaining portion having a longitudinal dimension approximating tne tnickness of a patient's retina, choroid, and sclera and including one or more peripheral grooves for receiving sclera tissue displaced oy tne forward end portion, and ΛΛ enlarged nead naving a radially outwardly extending flange foe engaging tne retina in tne area surrounding the opening formed by the forward end portion. In one embodiment, the forward end portion is generally conical, tne retaining portion nas a generally cylindrical surface, eacn groove has radially outwardly extending forward and rear side walls, and tne groove forward side wall forms a sharp corner witn tne outer surface witn tne retaining portion. The rear side wall of eacn groove preferably is outwardly inclined in a rearward direction to facilitate witndrawal of the tack in tne event of a retinal tear or tne like. Tne retinal tack is relaasably carried on tne tip of a tubular probe selectively connected in fluid communication witn sources of suoatmospheric and superatmospe ic pressure and the nead includes a seat portion wnich is received by and sealingly engages a complementary seat in tne probe tip. In one embodiment, the head includes a collar extending rearwardly from the flange, a reduced stub portion whiσn fits inside tne probe tip, and a cnarafered portion wnicn connects tne stub portion witn a collar and sealingly engages a seat in tne probe tip. The retinal tack is releasably held in tne prooe tip by a negative pressure in tne interior passage of tne probe. Tne probe is inserted into the vitreous cavity through an opening in tne eyeball and tne tack is manually inserted through the retina, cnoroid, and sclera in tne vicinity of tne retinal tear until tne nead engages the retina and tne retina is moved against the choroid. A small positive pressure then is introduced into tne interior passage of tne probe to permit tne probe to be moved away from the tack and withdrawn from tne vitreous cavity tnrougn the eyeball opening. BRISF DESCRIPTION OF THE DRAWING Fig. 1 is a perspective, partially schematic view of a system for implanting a retinal tack of the invention. Fig. 2 is a cross-sectional view of a patient's eye with the implantation instrument probe shown in position after implantation of a retinal tack. Fig. 3 is an enlarged sectional view taken generally along line 3-3 in Fig. 2. Fig. 4 is an enlarged view of an alternate arrangement for the retinal tack and the implantation instrument probe. DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 illustrates a system 10 for implanting a retinal tack of the invention. The system 10 has a conventional pump assembly 11 including a vacuum pump 12 and an air pump 14 (both illustrated schematically) driven by an electric motor (not shown) and suitably housed in a cabinet 16. The vacuum pump 12 and the air pump 14 are connected in fluid communication with an outlet fitting 18. The system 10 also has an implantation instrument 20 including a cylindrical housing 22 having an interior passage which is connected in fluid communication with the outlet fitting 18 via a flexible hose or conduit 24. The implantation instrument 20 includes a needle-like, tubular probe 26 which resembles a needle for a hypodermic syringe and usually has an outside diameter of about 0.040 inch or less. The probe 22 has an interior passage 28 (Fig. 3) -5- connected in fluid communication with the interior passage of the housing 22 and, thus, with the outlet fitting 18 of the pump assembly 11. The interior passage 28 of the probe 26 is selectively connected in fluid communication with the vacuum pump 12 and the air pump 14 by an electrically-operated control valve 30 (illustrated schematically) . The control valve 30 is moved between "vacuum" and "pressure" positions by operation of a suitable hand- or foot-operated switch (not shown) . The outlet pressure of the vacuum pump 12 and the air pump 14 is indicated respectively by pressure gauges 32 and 34 on the front of the cabinet 18. The vacuum pump 12 is adjusted to provide a negative or subatmospheric pressure in the order of 19 in. Hg at the tip 35 of the probe 26. The air pump 14 is adjusted to provide a small positive or superatmospheric pressure in the order of 20 mm Hg at the tip 35 of the probe 26. Referring to Figs. 2 and 3, a retinal tack 36, including a piercing portion and a retaining portion described in more detail below, is carried by the probe tip 35 and is releasably held therein by a negative pressure in the order of 19 in Hg created in the interior passage 28 of the probe 26 by moving the control valve 28 to the "vacuum" position. Referring to Fig. 2, a 20-gauge wound is made in the eyeball 40 at an appropriate location and a standard cannula 42 is inserted therein and sutured in place to serve as a port. While observing the interior of the eyeball through a ophthalmosope or surgical microscope, a probe having a blunt end (not shown) is introduced into the vitreous cavity 44 through the cannula 42 and manipulated to lay the detached retina 46 back into place against the choroid 48. This probe is withdrawn from the vitreous cavity and the implantation instrument probe 26 carrying a retinal tack 36, with the control valve 28 in the "vacuum" position, is introduced into the vitreous cavity 44 through the cannula 42. The retinal tack 36 is positioned against the retina 46 at a location close to the tear and the piercing portion of the retinal tack 36 is manually pushed through the retina 46, choroid 48 and the sclera 50 until the retina 46 is moved against the choroid 48. The control valve 30 is then moved to the "pressure" position to create a positive pressure in the order of 20 mm Hg in the interior passage 28 of the probe 26. This small positive pressure assists in releasing the probe 26 from the retinal tack 36 and prevents the intraocular pressure in the vitreous cavity 44 from forcing vitreous fluids out through the probe 26. However, this pressure is low enough to prevent the retinal tack 36 from being driven further into the choroid 48 and/or the sclera 50. Depending on the extent of the retinal tear, two or more retinal tacks 36 may be required to hold the detached retina 46 in place. Fig. 3 illustrates a preferred embodiment of the retinal tack 36. The tack 36 includes a piercing portion 52 in the form of a sharply pointed forward end, an elongated retaining protion 54 extending rearwardly from the forward end 52 and an enlarged head 56 extending rearwardly from the retaining portion 54. The forward end portion 52 preferably is generally σoncial and nas a point which is as snarp as possible in order to minimize tearing of tne retina 45, cnoroid 48 and sclera 50 during insertion tneretnrough. The retaining portion 54 has a longitudinal dimension approximating tne tniσkness of tne retina 46, choroid 48 and sclera 50 and includes one or more peripnerial grooves for receiving sclera tissue displaced during insertion of the forward end portion 52 tnerethrougn. Tne retaining portion 54 preferably has a generally cylindrical outer surface 60. Tne outermost diameter of tne retaining portion 54 preferably is substantially constant along the lengtn tnereof and is equal to or greater tnan the maximum outer diameter of the forward end portion 52. The sclera 50 tends to conform to the exterior of the retaining portion 54 and portions of tne tissue extending into the grooves 58 assist in retaining the tack 36 in place. Each groove 58 has radially extending front and rear side walls 62 and 64. To further enhance retention, the forward side wall 62 preferably extends generally perpendicularly to the longitudinal axis 66 of tne tack 36 and forms a sharp corner 68 with the outer surface 60. Tne included angle of tne corner 68 between tne outer surface 60 and the forward side wall 62 preferably is about 90° or less. It has been found that rounded corners or corners of an obtuse angle generally provide poorer retention. It also has been found that providing tne retaining portion 54 witn a generally cylindrical outer surface provides better retention, probably because tne sclera tissue applies a more uniform pressure on a larger suface area. To facilitate removal of tne tack 36 after implantation in the event of a retinal tear or tne like, tne rear wall 64 of eacn groove 58 preferably is outwardly inclined in a rearward direction. The nead 56 includes a radially outwardly extending flange 70 wnicn engages tne retina 46 in tne area surrounding tne opening formed by tne piercing portion 52. Tne head 56 preferably nas a circular cross section and tne flange 70 preferably extends generally perpendicularly to the longitudinal axis 66 of tne tack 36. The head 56 also includes an annular seat portion adapted to be received by and sealingly engage a complementary seat on tne probe tip 35. In the embodiment illustrated in Fig. 3, the nead 56 has a circular collar 72 extending rearwardly from tne flange 70, a reduced, generally cylindrical stub portion 74 extending rearwardly from tne collar 72 and an annular, chamfered seat portion 76 connecting the stub portion 74 witn tne collar 72. The seat portion 76 is tapered radially inwardly in a rearward direction. Tne stub portion 74 fits snugly inside tne interior passage 28 of the probe 26 and tne seat portion 76 3βalingly engages a complementary annular seat 78 in the prooe tip 35 when a negative pressure exists in tne interior passage 28. Surface contact between tne outer end 80 of the probe tip 35 and tne collar 72 and between the wall 82 of the probe interior passage 26 and the stub portion 74 provides lateral support (i.e., resistance to torque applied on the forward end of the tack 36) against breaking tne seal between the tack seat portion 76 and the probe seat 78 wnen tne tack 36 i3 being implanted. Breakage of tnis seal could cause the tack 36 to fall away from the probe 26 and drop into tne vitreous cavity 44. Tne reduced diameter of tne stub portion 74 facilitates grasping with a foreign body foreσeps in tne event tne tack 36 is accidentally dropped into tne vitreous cavity 44. The outer dimension of tne head 56 is 19-guage (about 0.040 inch) or less so tnat it can fit througn a standard cannula for a 20-gauge wound. Tne overall lengtn of tne tack 36 will vary and depends primarily on tne tnickness of tne retina, cnoroid, and sclera of a particular patient. Tnat is, tne retaining portion 54 of tacks used in adult patients is longer than that for tacks used in children. As a guide, tne overall length of the tack 36 can be in tne order of about 0.060 to 0.110 incn. The retaining portion 54 can have a lengtn of about 0.01 to 0.02 and an outer dimension about 0.020 incn. Tne piercing section 52 can nave a length of about 0.025 to 0.045 inch. The overall lengtn of the head 56 can be about 0.02 to 0.03 incn and tne length of tne stub portion 74 can be about 0.015 to 0.02 inch. Fig. 4 illustrates an alternate embodiment of tne retinal tack designed for use in children and otner patients having tninner retina, choroid, and sclera. In tnis embodiment, the length of the piercing section 52a of tne retinal tack 36a is sligntly less, the length of the retaining portion 54a is shorter (but still approximately tne thickness of tne retina, cnoroid, and sclera), tne retaining portion 54a includes a single groove 58 and the head has a different seating arrangement. More specifically, the entire outer surface 84 of tne head 56 is tapered radially inwardly in a rearward direction and serves as a seat which sealingly engages a complementary seat 86 in tne probe tip 36a when a negative pressure exists in the probe interior passage 28a. In tnis embodiment, lateral support for the tacK 56a depends entirely on surface contact between the tapered surface 84 of the nead 56a and tne probe seat 86. Tnese two surfaces are configured to provide a tight taper-to-taper fit. Tne angle of taper for the head surface 84 and the probe seat preferably is about 10 to 20°. Witn an angle of taper greater than about 20°, application of relatively small torques on tne forward end of tne tack 36a will break tne seal between tne nead surface 84 and tne probe seat 86. On the otner hand, witn an angle of taper less than about 10°, the walls of the probe tip 36a become quite fragile and make it more difficult to pick up tacks. It should be understood tnat both tne head arrangements illustrated in Figs. 3 and 4 can be used on retinal tacks having a retaining section including one or a plurality of grooves. The retinal tack can be fabricated from various relatively hard, inert, non-blood corrosive materials suitable for use in a numan body, including commercially pure titanium and plastic materials such as polyacetals and polyetnylmethacrylate. At the present time, commercially pure. Grade 4 titaminum is prefered because it can be maσnined to provide tne desired configurational features, particarly a snarp point on the piercing portion, the sharp corner between the front side walls of tne grooves and tne outer surface of tne retaining portion and tne tapered 3eat on tne head. From tne foregoing description, one skilled in the art can easily ascertain the essential cnaracteristics of tne invention and, without departing from the spirit and scope tnereof, make various cnanges and modifications to adapt it to various usages.

Claims: CLAIMS 1. A retinal tack for securing a detacned retina to tne choroid comprising a pointed forward end portion for piercing through tne retina, choroid, and sclera; an elongated retaining portion extending rearwardly from said forward end portion and having a longitudinal dimension approximating the thickness of a patient's retina, choroid, and sclera, said retaining portion including one or more peripheral grooves for reσeving sclera tissue displaced by said forward end portion during insertion theretnrough; and an enlarged nead extending rearwardly from said retaining portion and having a radially outwardly extending flange portion for engaging tne retina in the area surrounding tne opening formed by said forward end portion. 2. A retinal tack according to Claim 1 -wnerein said tack is releasably carried on tne outer end of a tubular probe having a tip and connected in fluid communication witn a source of subatmospheric pressure; and said head includes a seat portion adapted to be received by and sealingly engage a complementary seat in the proDβ tip. 3. A retinal tack according to Claim 2 wnerein said seat portion is tapered radially inwardly in a rearward direction. 4. A retinal tack according to Claim 3 wherein said head includes a collar extending rearwardly from said flange and a reduced 3tub portion extending rearwardly from said collar; and said seat comprises a tapered portion connecting said stub portion witn said collar. 5. An opthalmiσ tack according to Claim 1 wherein said forward end portion is generally conical; said retaining portion has a generally cylindrical outer surface; and each groove has radially outwardly extending forward and rear side walls and said forward side wall forms a snarp corner with said outer surface witn said retaining portion. 6. An optnalraic tack according to Claim 5 wnerein said rear side wall of said groove is outwardly inclined in a rearward direction. 7. An optnalmic tack according to Claim 6 wherein said retaining portion includes a plurality of said grooves in longitudinally spaced relationship. 8. A method for securing a detacned retina to the cnoroid including tne steps of providing a retinal tack adapted to be inserted tnrougn tne retina, choroid and sclera and having an enlarged head portion for engaging the retina after insertion, providing a tubular probe having a tip adapted to receive and sealingly engage tne nead of tne retinal tack and an interior passage extending to tne tip, placing the head of the retinal tack into tne tip of tne probe and reducing the pressure in tne interior passage of the probe to a subatmospheric level to releasably retain the tack in tne probe tip, inserting tne probe into the vitreous cavity tnrougn an opening in the eyeball and pushing tne retinal tack tnrougn tne retina, cnoroid, and sclera in tne vicinity of tne retinal tear until tne nead engages tne retina and the retina is moved against tne cnoroid; introducing a small superatmospheric pressure in the interior passage of the probe and moving tne probe away from the retinal tack; and withdrawing the probe from tne vitreous cavity tnrough tne eyeball opening.

Inventors: SINNETT KEVIN B, SINNETT, KEVIN, B.
Applicants: TREK MEDICAL PROD, TREK MEDICAL PRODUCTS
Application year: 1986
Main classification: A61B17
IPC codes: A61B17, A61F9