WOODCUTTERS TECHNIQUE

Area of Additional AttentionComparison between Chop & Woodcutter's technique

DEALING WITH NUCLEUS & ITS FRAGMENTS USING WOODCUTTER’S TECHNIQUE(Presented at AIOS,Rome & Germany, Published in OSN –Sept 2001)

Phacoemulsification procedure basically involves removing nucleus by dividing it in small fragments. For grade III & IV nuclei, chopping technique is considered as best amongst existing techniques. Author wants to highlight a new approach to divide such nuclei & has named this new technique as WOODCUTTER'S TECHNIQUE. When a woodcutter wants to divide a wooden log into two pieces, he first nails a chisel in the log. Some distance away from the chisel, he hammers on the log with an axe goes on hammering, slowly approaching chisel. As soon as he is very close to the chisel, the wooden log automatically gets divided into two vertical fragments .(as shown in fig.1). Woodcutter's technique is based on same principle.

In karate chop technique, we normally hold the nucleus with phacotip & then move chopper towards the phaco tip. As against this, in Woodcutter's, chopper is placed at same place & not moved. Instead, the phaco tip, which is holding the nucleus, is moved towards the chopper (with phaco on). This automatically divides the nucleus in two fragments, when phaco tip approaches near the chopper. Thus chopper acts like a chisel & phaco tip like an axe (as shown in fig.2). Remember that, phaco sleeve should be 1.5 mm behind the outermost point of phaco tip & you have to move phaco tip towards chopper with phaco on.

CHOP TECHNIQUE WOODCUTTER TECHNIQUE If you keep distance very small, depth of phaco tip entering inside nucleus is less & division becomes slightly difficult. For a harder nucleus this distance should be more If the distance is more, the irrigation may stop even if you withdraw phaco probe slightly. No sculpting or grooving in nucleus is required. It is easier to master woodcutter's technique with clear corneal incision.

The advantages of Woodcutter's technique are that ' it is fast to perform, you are away from posterior capsule as well as zonules, simple & easy even for phaco beginners and a boon especially for nuclei which are not so soft.

How to Learn ?

For Beginner -After you have mastered sculpting & making partial thickness groove you can directly start learning woodcutters technique. This can be better learnt by replacing nucleus in goat's eye by nucleus from stored eye bank eyes, which are not useful for keratoplasty. By this you get exact feeling of having operated on patient's eye. Make main Phaco and side port incision on goats eye. Then do capsulorhexis. Make a larger self sealing incision of about 6mm on goats eye from opposite side. Then push the nucleus taken out from the eye bank eye through the large incision. Embed this nucleus in soft cortex of goats eye by passing through capsulorhexis. Then suture the large incision. Now learn woodcutter technique on this nucleus. For that matter you can learn any technique of dividing nucleus in this way.

For Phaco master- Follow the steps (see above) in grade three or four cataract. Do not get disheartened even if you are unable to do it in first case. The technique shall not do any harm to the patient's eye even if it fails. Gradually you shall be master enjoying the fruits of learning this technique.

This technique is the best way to deal with harder nuclei like grade II, III, and IV.

Steps of woodcutter’s technique

Phaco sleeve should be 1.5 to 2 mm behind the outermost point of Phaco needle. The exposed tip (portion of the Phaco needle, which is not covered by sleeve) should be slightly more as compared to that required for routine chop technique. If you keep distance very small, depth/part of Phaco tip entering inside the nucleus is less & division becomes slightly difficult. For a harder nucleus tip exposed should be more. If the distance is more than required, the disadvantage is that irrigation may stop even if you withdraw Phaco hand piece slightly. (This is because the irrigation ports come near the incision and get covered by incision)For this technique there is no need of sculpting. Similarly no need to make a groove in nucleus. This technique can be directly applied to divide nucleus

Steps –

Part of the Phaco needle, which is not covered by sleeve, should be slightly more as discussed earlier.

Both the instruments i.e. Phaco needle and chopper are introduced inside in the anterior chamber.

Push the nucleus slightly (by one millimeter) to opposite clock position (opposite to the incision site) with the help of a chopper.

Embed the Phaco tip into the nucleus. You should enter keeping hand piece 70 to 80 degrees vertical. The advantage of this is that the tip gets fully embedded inside before you reach the center of nucleus or center of capsulorhexis.

When the preset vacuum is reached, pull the nucleus towards incision site by one mm. Embed the chopper at capsulorhexis margin into the nucleus. This is possible only when you are holding the nucleus firmly with Phaco tip.

Push the Phaco tip with Phaco on towards the chopper. This will break the nucleus into two vertical fragments in nearly all the cases. If not, then introduce the chopper into the depth of the crack that you have made and try to separate two fragments from each other. It is necessary to go to the base of the crack with chopper because it is easier to displace fragments without stretch on zonules. If still you cannot divide the nucleus, which may happen in the beginning then rotate

the nucleus by 180 degrees. If rotation is not possible, repeat hydro dissection. Try to rotate again. Once rotation is complete through 180 degree, again perform the same procedure as mentioned earlier.

For second crack or cleavage rotate the nucleus. The previous groove (which is created by movement of Phaco tip towards the chopper) gives you space. (You get more space as hard central part is taken out). This space can be utilized for inserting Phaco needle in the center and again dividing the nucleus in above-mentioned manner.

The procedure is repeated till small fragments of nucleus are made. In most of the cases you will be able to achieve fragmentation of nucleus into two pieces; except in very soft nuclei.

Advantages of woodcutter’s technique

While making division of nucleus you are always away from posterior capsule. Hence there is no danger of rupturing it.

The chopper stabilizes the nucleus. Because of this, stretch on zonules is less. This is why I am using Phaco power to divide nucleus rather than chopper. Chopper only stabilizes nucleus, & gives direction for crack to develop. As told earlier, chopper can be compared to the chisel stapled in the log of wood & Phaco to the axe.

As you are in the nucleus & then using Phaco power, even if power is more, it will not get dissipated towards, corneal endothelium, which minimizes endothelial damage

You get more space in the center as hard part is taken out when we move the Phaco tip towards the chopper with Phaco on.

You can increase vacuum to a great extent. Even if there is a slight surge, it won’t cause much harm as posterior capsule is far away & there is nucleus in between Phaco tip & posterior capsule.

Less power is required as Phaco is done after stabilizing nucleus with chopper as if you are feeding the nucleus in the Phaco tip.

Division is in one stroke most of times especially in hard nucleus. Less Phaco time is required as division is in one stroke. The procedure is fast to

perform. Secondly hard part of nucleus is taken out easily as if you feed it to the needle while moving Phaco needle towards chopper.

Cleavage extends beyond and deep in the substance of nucleus because of strain created by chopper. We may feel that Phaco needle will touch the chopper. But this will not happen because nucleus gets fragmented into two even before you reach up to the chopper. That’s why you will never go up to equator i.e. peripheral soft part of nucleus. The needle can become hot as Phaco is on with tip occluded.

In small pupil or small capsulorhexis it is possible to divide the nucleus as you do not have to go to the periphery and still you get the division of nucleus