Ординатура / Офтальмология / Английские материалы / Master's Guide to Manual Small Incision Cataract Surgery (MSICS)_Garg_2009

Figure 23.7: Dr Anil Shah’s modified snare (loop trisector)

shifting of the loop in to seggital plane over the nucleus is possible.

•Wire is so sharp that it can easily cut the hardest nucleus.

•A thin wire is passing large lumen of needle permit smooth movement of loop in to the anterior chamber.

INDICATIONS

This technique is indicated for all sizes of pupil and all types of nuclei.

CONTRAINDICATION

This technique is contraindicated in:

1.Subluxated lens.

2.Patients on anticoagulant therapy. These patients bleed more during scleral tunnel incision and in such cases it is advisable to perform standard limbal surgery.

It is relatively contraindicated

3.In very high myopia. In such patients, sclera is unusually thin and it requires additional care while making the scleral tunnel incision.

4.In high hypermetropia. In such patients the eye is unusually small, angle is narrow and there is crowding of angles of anterior chamber and thus proper care is required while making the incision.

ANESTHESIA AND PREOPERATIVE PREPARATION

Preoperative antibiotic drops, oral antibiotics and preoperative mydriatics are according to individual choice. Wash the face with soap, clean the area around the eye with spirit and paint it with Betadine.

In recovery room, patient receives a peribulbar block. Give 3 ml Xylocain with Adrenaline plus 2 ml Sensorcain with Hylase at lateral 1/3rd of the lower lid. Give 2 ml Xylocain with Adranaline plus 1 ml Sensorcain at medial 1/3rd of upper lid.

Put a drop of Betadine into the inferior fornix and apply super pinky ball or balance wait for 10 minutes.

Figures 23.8A and B

After this, patient is taken to operation theater. Apply staridrap to cover the lids and lashes. Apply

lid speculum and a bridle suture may or may not be taken.

PREPARATION OF WOUND

Do every step during the surgery clearly and precisely to get the best possible results. Prepare fornix base canjunctival flap. Detach conjunctiva from limbus and keep a small tag of conjunctiva at center of incision. This helps holding and rotating of globe, Severe Tennon’s capsule attachments and cauterize the exposed area to stop bleeding. Use minimum cautery (Figures 23.8A and B).

SCLERAL TUNNEL INCISION

Temporal approach is convenient than upper limbal approach.

Perform surgery either at the right or at the left side of temporal area depending upon which side of the eye is to be operated. Initial difficulties are easily mastered with practice (Figures 23.9A to C).

Advantages of Temporal Incision

•Wide space is obtained (on temporal sides) for making scleral tunnel incision with straight blade.

•Straight blade, snare and long straight instrument are easy to use.

Figures 23.9A to C

•No need to cut eye lashes.

•Scleral incision is on the side of eye ball, so less irritations to the patient. Also the incision is on slope, so there are less chances of getting infection.

Crescent blade available in the market can be used for scleral tunnel incision. These blades are costly but cannot be used repeatedly.

I do scleral tunnel incision with 11 and 15 number surgical blade. These are the lowest cost disposable blades easily available in the market. It works on the principal of carpenters’ saw. It is known that although the saw has blunt edge, it cuts the wood easily. There is no force is applied while cutting wood. On the same principal do not apply any force with these blades while making scleral tunnel incision.

With 11 and 15 Number Blade (Figures 23.10A to F)

In the beginning, it is suggested to make the incision within 2.0-2.5 mm away from the border of anterior limbus. It is important to control depth of groove and uniformity, throughout the length of incision.

On the temporal side with 11 number blade, make a straight 5.5 mm long partial thick scleral incision which should be perpendicular to the scleral surface.

Tilt the blade at 45 degree and give repeated light strokes with blade along the length of incision to obtain a small groove.

Now with 15 number blade gives few strokes in the center of the incision. Tilt the 15 number blade at 45 degree and give light strokes with curved edge of the blade along the length of the incision to obtain small groove. Do not apply any force. Now give few strokes in the center of the incision. The blade should be parallel

to the surface of limbus and cornea. Undermine the central incision with the blade in the clear cornea for about 0.5 to 1.0 mm.

Now extend the incision laterally with the edge of 11 number blade on either side along the entire length of incision.

With side to side movement of the 11 number blade extend the central tunnel laterally to the full width by lateral movement of the blade on either sides. Make the squaring of scleral tunnel. Do not go in to the angle of anterior chamber otherwise bleeding may occur.

Few complications like buttonhole of flap, peripheral entry to anterior chamber, hyphema and postoperative astigmatism with the rule are possible. Meticulously performed technique will minimize the complications.

While doing scleral tunnel incision, make a conscious effort not to enter prematurely into the anterior chamber.

ANTERIOR CHAMBER ENTRY

(Figures 23.11A and B)

Lift the edge of scleral incision with the forceps and pass 11 number blade inside the scleral tunnel keeping the tip of the blade facing towards the center of pupil (Figures 23.12A and B). Pass the blade parallel to the limbus up to the clear corneal surface and pierce the same.

STAINING OF CAPSULE (Figures 23.12A and B)

If the fundal glow is not seen inject air bubble and tryphan blue to stain the capsule. After few second

Figures 23.11A and B

Figures 23.12A and B

irrigate the anterior chamber with saline and wash out air bubble and tryphan blue. Then inject viscoelastic to fill the anterior chamber.

If the fundal glow is seen then staining is not required. Fill the anterior chamber with viscoelastic.

SIDE PORT INCISION (Figures 23.13A and B)

Make a side port entry at right angle to the scleral tunnel incision with blade or disposable needle.

•20 G disposable needle is used to make entry into the anterior chamber (Figures 23.12A and B). Keep the tips of the needle parallel to the iris surface. With the bevel facing downward, pierce the needle at the anterior limbus till the tip enters into the anterior chamber. Give counter pressure on opposite side

enter it through side port. Make small vertical nick on the mid periphery of anterior capsule at 5 o’clock position. Lift the capsular flap and turn the flap to left side up to 2 o’clock position. Shift the needle at 5 o’clock position and lift up the capsular flap and turn it to the right side up to 10 o’clock position. Enlarge the scleral tunnel incision then pull the flap towards 12 o’clock position with McPherson forceps. Cut the capsular flap at 12 o’clock with the scissors.

This capsulotomy has various advantages.

•It is easy to perform.

•Nucleus pole can easily be tipped up to the anterior chamber at 12 o’clock position.

•Due to large size of capsular opening, the large nucleus is easily tipped up.

•It is easy to aspirate the subincisional cortex. This ‘D’ shape capsulotomy provides easy insertion of the IOL inside the bag.

Capsulorhexis

To get good capsulorhexis, the anterior chamber is made deep with viscoelastic solution or with anterior chamber maintainer. If the anterior chamber becomes shallow there are chances of getting radial tears to the anterior capsule. This occurs due to zonuler stress or by tenting of anterior capsule.

Larger capsulorhexis has many advantages. The nucleus is easily brought in to the anterior chamber and surgery is made easier. It removes sub capsular epithelium which minimizes postoperative formation of after cataract. Always prefer capsulorhexis than capsulotomy. It is stronger. It stretches from its original size. Its edges do not radiate towards zonules as the edges are smooth and tough. Aspiration of residual cells

from anterior capsule is easy due to tough rim. IOL fits exactly in the center of capsular bag. If the tears occur on the posterior capsule, the rim of anterior capsule permits the fixation of IOL in the sulcus.

Using a bent needle, 26 G, a perforation is made in the center of the anterior capsule.

Method

With the tip of needle a small flap of anterior capsule is lifted (Figures 23.14A to F). The tip of the needle and the capsular flap is redirected towards 12 o’clock position. This creates a flap with the smooth curve as it is beginning. The flap is pulled along the circular manner by means of gentle traction with the help of needle towards 10 o’clock position. Release the flap and refold, as the flap progress. Large amount of capsular fold will present and must be pushed away, so that one can visualize the exact point at which, to place the tip of the needle. Rotate the flap towards 6 o’clock position and redirect towards 3 o’clock position. From there complete the rhexis at the starting point. When completing the capsulorhexis, one should overlap tear such that the last part of tear joints the first part from out side towards the center, thus resulting continuous edge.

Capsulorhexis forceps can be used to perform capsulorhexis. Initial puncture in the anterior is made with 26 G needle and the rest of the rhexis is continued with forceps.

EXTENSION OF CORNEAL INCISION

(Figures 23.15A and B)

Extend the inner corneal incision with the 11 number blade parallel to the scleral tunnel on one side. Then

shift the edge of the blade and extend the incision at the other end. This makes a clear corneal incision. Complete the squaring of incision with 11 number blade. Make the width of inner incision longer than outer incision. The inner incision acts as corneal valve incision.

HYDROPROCEDURE

Hydroprocedure is very important to make the nucleus, epinucleus and cortex free the capsular bag. It hydrates the nucleus, epinucleus and cortex. It helps easy delivery of nucleus to the anterior chamber, reduces the size of nucleus and loosens the cortex.

Remove some amount of viscoelastic from anterior chamber. This reduces intraocular pressure so that when the fluid is injected there is no rise intraocular pressure or iris prolapse is prevented. During hydroprocedure there are three steps.

Cartico Cleavage Dissection (Figures 23.16A and B)

It is seen that when anterior capsulotomy is done, cortex does not become adhered to capsule. This is due to natural cleavage between capsule and outer cortex. So taking advantage of this natural cleavage, one must create separation between anterior capsule and outer cortex.

To do this, attache 26 G cannula to 1 cc syringe filled with ringer lactate (Figures 23.15A and B). Pass the tip of cannula under capsular rim. Lift the anterior capsule

with the cannula, do slight tenting of anterior capsule and inject little fluid under the anterior capsule. See a fluid wave passing under the capsule behind the nucleus. It creates a cleavage between capsule and outer cortex. This is a very important step. It should be done carefully otherwise it may rupture posterior capsule or zonular dialysis may occur. With this step, almost all the cortex is separated from capsule. If the fluid wave is not seen, then do this maneuver on different parts of the capsule to achieve good results.

Hydrodissection (Figures 23.17A and B)

Pass the tip of 24 G cannula in the substance of cortex and epinucleus. Inject sufficient fluid to dissect the cortex and epinucleus. If the dissection is not complete, repeat this procedure on different parts to obtain complete dissection. Commonly, adhesions are seen at 12 o’clock position. So one might need to go via side port incision and inject the fluid into the cortex under the anterior capsule. These steps help making the epinucleus free from the cortex.

Hydrodelineation (Figures 23.18A and B)

By this procedure, one can determine the degree of nucleus hardness. Take 2 cc syringe fill it with ringer lactate, attach 24 G cannula having sharp bevel cannula

Figures 23.18A and B

(45 degree angle). Pass the pointed tip of the cannula into the substance of nucleus, until one feels the resistance of inner nucleus. This is the point which indicates the separation of soft outer nucleus and firm inner nucleus. In some cases the point indicates separation of fetal nucleus and adult nucleus.

At that point of resistance, withdraw the cannula for a fraction of millimeter and inject fluid at this point. It creates the cleavage plane producing a circular ring known as “golden ring” around the inner nucleus. If the ring is not complete do the above maneuver at different areas and try to inject the fluid till the total ring is obtained.

In hard cataract, identification of cleavage is difficult as outer portion of nucleus may extend up to the capsule.

In soft cataract, several cleavage planes are seen.

NUCLEUS PROLAPSE

The next step is delivery of nucleus into the anterior chamber. Tipping up the nucleus into the anterior chamber is the most important step. Various types of methods are available to bring the nucleus into the anterior chamber.

Methods

1.Use retractor to retract the capsule and iris. Nudge the superior pole of nucleus towards 6 o’clock position and tip up the superior pole of nucleus. Place viscoelastic solution in between the superior pole of nucleus and posterior capsule. Insert the lens loop beneath the nucleus about half way down towards 6 o’clock position and with slight upward nudge, prolapse the nucleus into the anterior chamber (Figures 23.19A to F).

Figures 23.19A to F

2.Keep the retractor in the left hand, insert it into the anterior chamber and retract the iris and capsule. Nudge the superior pole and lift the nucleus upward with the tip of irrigating cannula is first withdrawn to clear the cortical material that blocks the cannula. The irrigating cannula is moved beneath the nucleus towards the interior pole. Simply lift up the nucleus with the cannula to prolapse the nucleus into the anterior chamber.

3.I prefer this method. In this method, a 22 G cannula with opening facing downward is attached to irrigating bottle. Pass the tip of the cannula under the capsule differently at 3 o’clock or 6 o’clock or 9 o’clock positions deep up to the equator. Fluid goes under the capsule behind the nucleus and pressure is built into the capsular bag. Due to fluid pressure, it pushes the pole of the nucleus out of the capsular rim and papillary border. Now inject viscoelastic solution in between the cleavage of iris and nucleus. Spin the edge of the nucleus with the tip of modified viscoelastic cannula into anterior chamber. Intermittently inject viscoelastic solution to keep the anterior chamber deep. While spinning the nucleus, be careful while rotating the edge of the nucleus, as sometimes the rim of the capsule remains attached to the edge of nucleus.

Figures 23.20A and B

Make the nucleus free floating into the anterior chamber. Inject viscoelastic solution above, below and to the sides of the nucleus.

4.In few complicated cases, where the nucleus is large or pupil is small, it is difficult to bring the nucleus into the anterior chamber. In such cases, I use this method. With retractor in right hand, retract the iris and capsule at 12 o’clock position and press the posterior scleral incision downward. Now in the left hand, take 2 ml empty syringe and attaché hydrodissection cannula. Pass this cannula through 2 o’clock side port incision towards 6 o’clock position under the rim of anterior capsule. With the tip of the cannula, press downward the 6 o’clock pole of the nucleus. With tumbling movement 12 o’clock pole of nucleus is prolapsed. Now, to withdraw the retractor, push the 12 o’clock pole into the anterior chamber above the iris plane and get it withdrawn. Inject the viscoelastic solution in between the nucleus and iris, and by spinning the edge of nucleus, prolapse the nucleus into the anterior chamber (Figures 23.20A and B).

NUCLEUS FRAGMENTATION

The most important step is nucleus fragmentation. This is the key part of the whole procedure. Viscoelastic solution plays very important role in it. It keeps the nucleus free floating into the anterior chamber. Hypotony makes the surgery safer.

Inject adequate amount of viscoelastic solution between the endothelium and anterior surface of nucleus. Continue injecting viscoelastic solution to the sides and then beneath the nucleus. It separates cortex and epinucleus, which is adhered to the nucleus, the viscoelastic solution also separates the nucleus from iris and posterior capsule and keeps the anterior chamber deep. This gives adequate amount of space for the movement of snare into the anterior chamber.

Figures 23.21A to D

Before using the snare it is essential to check the following things:

•Push and pull the handle of the snare and observe the smooth movement of wire loop.

•Before using the snare, reshape the loop and make it oval.

•If the wire loop is bending, make the loop straight.

•The loop of snare should not be damaged or kinked.

Bisection (Figures 23.21A to D)

Snare is used for bisection of any grade of nucleus. Hold the hub of the needle between thumb and forefinger of left hand and the wire loop handle in the right hand. Partly close the loop before passing it into the anterior chamber. Pass the loop in slightly tilted position to the left side angle of the anterior chamber. One arm of loop remains above the nucleus and another arm below the nucleus.

Shift the loop to vertical position and simultaneously open the loop by pushing wire holder. Rotate the hub

Figures 23.22A to C

of needle externally and due to its two side opening, the loop gets rotated into the anterior chamber, until it encircles the body of nucleus in sagittal plane at proper position.

If the loop is over sized, reduce the size by pulling handle. When the loop engages the nucleus, it buries the anterior limb of the loop into the viscoelastic solution and cortical debris, well away from the endothelium and the posterior limb remains away from posterior capsule.

Hold the nucleus properly in the wire loop. Try to keep wire loop in the center of the nucleus. Constrict it by pulling the wire loop posteriorly. Hold the snare firmly and divide the nucleus into two equal halves.

The nucleus portions frequently adhere to each other like warm wax. Inject viscoelastic solution in the groove of the nucleus, to force them apart. Separate the nucleus and demarcate these two halves clearly.

With this the bisection of the nucleus is completed (Figures 23.22A to C).

Trisection

With Bisector (Figures 23.23A and B)

Figures 23.23A and B

Figures 23.24A and B

With bisector trisection can be done if the nucleus is large even after bisecting, then rotate it. Bring the large portion of nucleus to the left side so that its cleavage line points toward the right end of incision. This counterclockwise rotation of the nucleus compensates for the tendency towards clockwise rotation when the snare is inserted.

Now fill the anterior chamber with viscoelastic solution and pass the bisector loop as above and make another section to divide nucleus into three fragments.

With Trisector (Figures 23.24A and B)

Trisector is rarely needed for trisection of nucleus. Nucleus is brought in to the anterior chamber as described before. This trisector has two loops and has concavity facing opposite to each other. Pass one loop of trisector from left side of nucleus to right side over the center of the nucleus. The second loop automatically engages other side of the nucleus. Pull the wire loop posteriorly which divides the nucleus into three fragments. When the loop is withdrawn, central part of