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Instruments used in Cataract Surgery:

Simcoe's irrigation- aspiration cannula:

Design: Available in two different designs. Original model also called the direct Simcoe where, aspiration is through the silicone tube and irrigation through the main hub .The surgeon holds the syringe attached to the silicone tubing which is used to generate suction for aspiration in his/her left hand and the irrigation line is attached to the main central hub.
The other model is the Reverse Simcoe where irrigation is through the main hub. The surgeon uses a syringe attached to the main hub to generate suction for aspiration.
Cannulas are available in different sizes: 21,22,23 gauge which have an aspiration port size of 0.5,0.35,0.3 mm respectively. These are 15 mm long in size with angled front opening.
Some models come with sandblasted tip for polishing posterior capsule.
The narrow bore ports are useful for aspiration of fine cortical fibers  and get a better hold of tissue ,while large bore cannulas are useful for faster aspiration of bulky cortex.

Advantage: Aspiration of cortical matter is controlled.

Disadvantage: As the bore is large, it cannot be used in SICS and Phacoemulsification without enlarging the side ports.

Use: Manual aspiration of the lens cortex .It has dual function of irrigation and aspiration. Can also be used for aspiration of other material from the anterior chamber such as visco elastics , hyphema, exudates.

Complications : PCR, Zonular dialysis.


Choppers:

Different designs of choppers are available to facilitate cutting and splitting of the lens nucleus which is known as nucleotomy . The choppers facilitate nucleus removal using a two handed technique holding the chopper in one hand and the phacoemulsification probe in the other.
Some choppers have a blunt rounded tip and sharp inner cutting surface for horizontal chopping.  Others have a sharp pointed tip for vertical chopping and dividing or splitting the nucleus.

Advantages:
1) More efficient removal of the hard inner nucleus minimizing the phacoemulsification energy as in chopping the critical instrument maneuvers are primarily kinesthetic and are performed with chopper tip( lamellar orientation of the crystalline lens fibres creates natural fracture planes).

2) One does not need the red reflex to visually gauge the depth of the instrument tip.

3) During sculpting ,the nucleus is fixated by the capsular bag, in comparision ,chopping applies much less force against the zonules because the phaco tip secures the nucleus.

4)Useful in complicated cases like brunescent nuclei, total cataracts, small pupils ,weak zonules.

a. Horizontal Chopper :

There are many different horizontal chopper designs, but all feature an elongated tip ,which is blunt in order to avoid capsular perforation. A relatively long tip is necessary in order to transect thicker,dense nuclei and inner cutting surface of the tip may be sharpened for this purpose. Different choppers come with variable angulations of the tip. The classic Nagahara's horizontal chopper comes with 1.5 mm inner cutting edge and 0.25 mm blunt polished tip.The cutting edge is 90 degrees to the shaft. Angulation of the shaft to handle is 45 degrees .Tip to angle length is 14 mm .Overall length of the instrument is 127mm.Can be used by right or left side port..

Technique: It is called horizontal chop because the instrument tips move towards each other in the horizontal plane during the chop. As the initial step the central anterior epinucleus should be aspirated with the phaco  tip. The chopper tip is entered through the side port made at 1-2 o'clock and it touches the central endonucleus and maintains contact as it is passed peripherally beneath the capsulorhexis edge. This ensures that the tip stays inside the bag as it descends and hooks the endonucleus peripherally. Once it hooked the nuclear equator,the nucleus is deeply impaled with the phaco tip. Then the chopper tip is pulled directly toward the phaco tip, and upon contact ,the two tips are moved slightly apart. This separating movements propagates the fracture across the entire nuclear diameter.
The nucleus is rotated and the same maneuver is repeated in order to create a pie shaped fragments.

Advantage: Better suited for softer nucleus , highly myopic eyes, vitrectomized eyes.

Disadvantages: Chances of capsular laceration.

B). Vertical Chopper :

Common to all vertical chopper designs, is a short but sharpened tip that is able to penetrate the nucleus. Vertical choppers contain an axe like tip. The axe is 0.75*0.75 mm in dimension. Angulation of the shaft to handle is 45 degrees. Tip to angle length is 10 mm.

Technique: It is called vertical chop because the chopper utilizes a shearing force to split the nucleus vertically into pieces. The initial step is to engage the nucleus with phaco tip in atleast 50% of the nucleus thickness  using high vacuum. Then the axe of the vertical chopper is advanced vertically downwards just in front and adjacent to the phaco tip to create a vertical QUICK CHOP in the nucleus. The phaco tip now moves in upwards and outwards direction to bring the fragment of the nucleus away from the axe ,which holds remaining portion of the lens in position converting a cleft into a crack. The final motion is to separate axe and the phaco tip apart to impart a full thickness crack in the nucleus.

Advantages: Better suited for hard nuclei becuase it requires the nucleus to be brittle enough to be snapped in half.

Disadvantages: Uses more compressive force so less useful in cases of weak zonules.

DOUBLE ENDED CHOPPER : One end contains horizontal and other end contains vertical component of chopper. Many designs available with microfinger pointed vertical or horizontal chopper tip and other end with nucleus rotater. Vertical and horizontal choppers are complementary to each other so double ended chopper provides both tips on a single instrument.


Slit Enlarging Keratome (5.1mm)

Design: This is a disposable keratome mounted on plastic handles with angulation of 45 degrees with different designs like straight,bevel up or bevel down.
It has a blunt tip.

It is 5.1 mm wide with cutting edges on both sides

Use: it is used for extension of a keratome slit for either converting a phacoemulsification case to SICS or for inserting non foldable IOL.

Disadvantage: It has a blunt tip which can cause Descemet's membrane detachment if not handled carefully.


Shapiro’s Posterior Capsule Polisher

Description: Posterior capsule polisher 23-gauge curved shaft with dual irrigating 0.3 mm tip.

Uses: Posterior capsule may be prepared for lens implantation using this PC polisher after lens cortex aspiration. Can be used to remover fine, sticky cortex adherent to posterior capsule, PC plaque or small PC cells which can cause obscuration of the visual axis in the post-operative period and early PCO formation.