The Sharpedge System was introduced in India in the year 1992. The blades of this system are also known as Microsurgical blades. Microsurgical blades were originally introduced in the U.S.A. to improve the visibility while doing the surgery under the microscope.  Initially the miniature version of the more popular blades like number 11 and other carbon steel were introduced.  Subsequently surgery became more intricate with the advent of phaco emulsification and small incision surgery.  This change gave a big impetus to the use of Microsurgical blades.

The Manufacturing Process:

Following are the main steps involved in the manufacturing process:

• Blanking: Here the stock material is given the shape of the blades by blanking using the punch press.  Close watch is exercised in this step to monitor the slow degradation of the blanking tool.

• Heat Treatment: Here the blanks are heated to a certain temperature and then suddenly quenched to room temperature.  With this the material  achieves the required hardness.  Our blades have hardness in the range of 50 to 54 Rockwell C (HRC).

• Grinding: Here the cutting edge is actually formed.  This step may have one or multiple stages of grinding depending on the type and required finish of the blade.  Jigs/fixtures or free hand methods are employed depending on the intricacy of the shape of blade.  Here the bulk of the material is removed at a faster rate.  Towards the end of this process the thinned out material bends over a little resulting in an extended unwanted portion called 'FEATHER'.

• Buffing / Polishing: This step, like grinding, is also basically that of metal removal, but at a  much lower rate and at much reduced pressure.  It just removes the unwanted extension called 'FEATHER'.  This step is very critical as overdoing it even marginally, can spoil a good well ground blade. So this is where extreme skill is required.

• Packing: Here, after cleaning and degreasing, the blades are blister packed with the cutting tips/edges well protected with high density foam.

Inspection Procedure:

The inspection schedule is given below along with the parameters being checked:

The most important step is the buffing inspection prior to packing. The most important parameter here is the sharpness of blades. Unfortunately there is no simple instrument / method suitable for mass inspection that can directly check sharpness.  There are sophisticated equipments that can measure the force required for the tip of the blade to penetrate into a taut membrane of leather or polyester.  We limit the use of this method to evaluate new processes, batches of materials etc.  This process obviously would be too expensive for mass inspection.  The blades are checked visually under the magnification of 30X for checking the sharpness.  The experienced inspector gets a fairly good idea about the sharpness of the blade, therefore marginal to moderate piece to piece variations  in sharpness are to be expected.

Components of the System:

The Sharedge system has two subsystems as given below:-

 
A) FLAT STOCK SYSTEM :  The blades of this system have four digit product numbers. The Flat Stock system is called so because the blades of this system are made from the base material of flat strip while the round stock blades are made from base material of round wires.  Each of these subsystems consists of blades, blade holders and full handled knives.
 

Suture Cutter:This is a hook type design with inside cutting edge radius of around 2.75 mm.  This cutter can be used for varieties of sutures.

• Cataract Blades:These blades are available in three sizes blade # 5210 small (20 mm),          blade # 5220 medium (23 mm) and blade # 5230 large (27 mm). These blades are primarily designed to make sclerocorneal section in the upper segment in ICCE procedure. These blades can also be used for making limbal incision during other operations e.g. Paracentesis, Glaucoma Iridectomy.

• Miniature Blades:These blades are the miniature versions of the conventional scalpel blades.  But some of these blades have substantial refinements in shape to make them functionally superior e.g.. sharp all round blade # 6900 (straight) and 6910 (angled); lamellar blade # 6600 (angled) and 6610 (straight).

• Slit Blades: These blades are used to get the slit opening of precise width.  They are available in two versions : Pointed Tip - for entry; Blunt Tip - for extension (the tip is made blunt to avoid secondary incision).  Both these versions are available either straight  or angled at 45 degrees. The angled version is by far more suitable and it is preferred by more than 95% of the users.  The sharp tip version is available from 1.5 mm to 5.2 mm width while blunt tip version is available from 4.0 mm to 7.2 mm width.  The 5.2 mm blade is offered in sharp tip version to meet the demand of some users who prefer to avoid using an additional blade for extension.

• Scleral Blades: These blades are popularly known as hockey knives.  These can be used for scleral incision for variety of procedures.  They are available in two versions : blade # 5700 - wide tip; blade # 5710 narrow tip.

• Spoon Blades : These blades have a circular cutting edge spreading over 270 degrees and are available in two diameters: 1.5 mm - blade # 6810 (straight)  blade # 6820 (angled); 3.0 mm - blade # 6811 (straight) blade # 6821 (angled) blade # 6821E ( angled with extended neck).  All these blades were introduced with the intention of using them for making the scleral tunnel.  Of late the use of these blades is reducing in favour of more refined and specialised blades introduced subsequently i.e. tunnel pocket blades and crescent blades (round stock).

• Tunnel Pocket Blades: This blade is one of the more complicated designs requiring multiple stages of grinding.  These blades are available in two versions: blade # 4805 - angled; 4806 # straight.  These blades are used for making the scleral tunnel.

• Blade Holders : The reusable metallic chuck type blade holders are made either of stainless steel or of  titanium. In case of stainless steel two different types of designs are available : two piece design and the three piece design.  The three piece design has detachable chuck and outer sleeve while the two piece design has detachable chuck but the outer sleeve is one piece with the main body.  Two piece design has got the advantage of simplicity of construction offering ease of maintenance.  The three piece design though little more complicated is preferred by majority of users mainly because it offers the convenience of tightening  the chuck using the outer sleeve.  Because of strong preference of the three piece design titanium holders are made with this design and with the length of 9.5 cm.  Both the design of stainless steel holders are available in two lengths : 9.5 cm long - 2PM (two piece design) and 3PM (three piece design); 13 cm long - 2PL (two piece design) and 3PL (three piece design).

• Full Handled Knives : All the Sharpedge Blades are available in this version.  The holders to which the blades are permanently fixed, are made of black coloured polycarbonate.  These knives can be autoclaved as polycarbonate can withstand temperatures upto 115 degree Centigrade.  This version offers great convenience as it totally eliminates the need for the maintenance.


B) ROUND STOCK SYSTEM: The blades of this system have five digit product numbers beginning with 9.  Wires of different gauges are used to manufacture the complete range of these blades.  Unlike flat stock system it is not possible to have a simple design holder that could fit universally, therefore four varieties of blade holders are developed to cover the full range.  For selecting the compatible holder for a blade one has to match the gauge of the blade with that of the holder.  The product description in the literature includes the information about the gauge.
 

• Crescent Blades: These blades are optimally designed for the scleral tunnel.  They are available in three versions:  blade # 940001 - straight; blade # 940002 -  angled bevel up; blade # 940003 - angled bevel down.  The angled bevel up version (blade # 940002) is by far the most popular blade for making tunnel.

• Lance Tip Blades: These blades are designed for making corneal or limbal stab incision.  They are very popular for making the side port.  They are available in two versions :  blade # 921501 - 15 degrees; blade # 923001 - 30 degrees.  Some users find these blades suitable for making the first scleral incision prior to making the tunnel.

• MVR Blades: These blades are designed to give precise water tight port.  They are very popular in vitreoretinal surgery.  They can also be used for making precise side port in small incision cataract surgery.  They are available in three versions : blade # 965556 - 19  gauge; blade # 96569 - 20 gauge; blade # 965573 - 24 gauge.

• Slit Blades : These blades are used to get slit opening of precise width.  They are available in two versions: Pointed tip - for entry; Blunt Tip - for extension ( the tip is made blunt to avoid secondary incision).  Both these versions are available either straight or angled at 45 degrees.  The angled version is by far most suitable and it is preferred by more than 95% of the users.  The sharp tip version is available from 2.5 mm to 3.5 mm width while blunt tip version is available from 4.0 mm to 6.2 mm width.

• Blade Holders : The reusable metallic chuck type blade holders are made of either  stainless steel or titanium.  Unlike flat stock system, only two piece design is available and also only single  length of 10.5 cm is available in round stock system.

• Full Handled Knives: All the Sharpedge blades are available in this version.  The holders to which the blades are permanently fixed, are made of blue coloured polycarbonate.  These blades are autoclavable as polycarbonate can withstand temperatures up to 115 degree centigrade.  This version offers great convenience as it totally eliminates the need for  maintenance.

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