(1)
Newcastle Eye Centre Royal Victoria Infirmary, Newcastle upon Tyne, UK
Electronic Supplementary Material
The online version of this chapter (doi:10.1007/978-3-319-59924-3_11) contains supplementary material, which is available to authorized users.
Two key surgical phacoemulsification skills to acquire are the ability to form a trench in the lens nucleus (referred to as grooving or sculpting), and the ability to apply pressure to the walls of the trench, dividing the lens nucleus into two smaller segments (cracking). Lens grooving and lens cracking form the basis for one method of disassembling the lens nucleus.
For simplicity, this chapter describes the true surgical sequence: grooving followed by cracking. However, when a rear-ended modular approach is followed, training in cracking should take place first. This will require the Trainer to prepare the lens nucleus before handing over to the Trainee.
The description is for a right-handed surgeon and transposition is required for left-handed surgeons. The terms trench and groove are used interchangeably.
The overall technique can be broken down several steps:
- 1.
Check the tip sleeve length and ensure irrigation ports are horizontal to the tip.
- 2.
Ensure irrigation and phaco probe is working.
- 3.
Insert the phaco probe into the anterior chamber.
- 4.
Check the sleeve is not caught on the corneal section and performing a pseudo-groove.
- 5.
Perform an initial true groove with correct ‘foot control’ sequence during phaco-sculpture of the lens.
- 6.
Perform a minor rotation in preparation for next step*.
- 7.
Prepare for and then crack the lens.
- 8.
Perform a major rotation in preparation for next step.
- 9.
Continue grooving and cracking all the remaining segments.
*Surgeons may prefer to perform a major rotation to pre-groove (sculpt) the lens into two halves and split the lens (Fig. 11.1), before additional grooving and cracking to create quadrants. Alternatively, some surgeons prefer to rotate and sculpt trenches consecutively in order to create a ‘cross’ appearance in the lens nucleus (Fig. 11.2). Each grooving trench can then be ‘cracked’ to form four fragments. This is referred to as ‘divide-and-conquer’, [1]. The principles for divide-and-conquer remain similar, but minor rotation and cracking will be omitted until all grooving is complete. The Trainer will instruct on which method will be used for any individual nucleus, and the novice must accept that the method may be altered intra-operatively depending on circumstances; if the trench looks good enough to crack why not split that area of the nucleus straight away? For Trainees who have developed phaco technique using dual linear control, the Trainer may request immediate removal of a fragment as it is created and separated from the main body of the nucleus (Fig. 11.3).
Fig. 11.1
Grooving and Cracking—hemi nucleus . Lens nucleus sculpted and cracked into two halves. Corneal light reflex artefact (short arrow), air bubble (long arrow)
Fig. 11.2
Grooving and Cracking—sculpted cross . Lens nucleus sequentially sculpted to form trenches which intersect to form a ‘cross’ shape. Cracking to disassemble the lens is required
Fig. 11.3
Grooving and Cracking—fragment creation and immediate removal . Lens nucleus sculpted (short arrow) at 90 degrees to initial trench (long arrow). Cracking has taken place and the created fragment immediately removed. Residual quadrant of cortical soft lens material highlighted by the red reflex is noted (arrow head)
11.1 Fundamentals
11.1.1 Phaco Probe
The phaco probe uses ultrasonic vibration to emulsify any lens material in close proximity to its metal tip. The “soup” of tiny lens particles is then removed from the eye as it is aspirated up the hollow phaco probe. A plastic sleeve that contains two irrigation apertures covers most of the phaco tip. This sleeve is adjusted according to the surgeon’s preference to ensure the exposed phaco tip is a suitable length (Fig. 11.4). During assembly, the phaco probe tip can inadvertently be passed through one of the sleeve irrigation apertures, or the sleeve may not be correctly rotated to allow horizontal flow of fluid from the probe. In view of this, the phaco probe tip must be examined before insertion into the eye to ensure it is adequately prepared. Commonly, the superior part of the exposed phaco tip is shorter than the inferior edge (Fig. 11.5).
Fig. 11.4
Phaco probe sleeve. Phaco tip (long solid arrow), mouth (arrow head), irrigation aperture (open arrow), phaco sleeve (short solid arrow)
Fig. 11.5
Phaco tip primary position in side profile. Aperture or ‘mouth’ (arrow head), exposed tip (long solid arrow), sleeve (short solid arrow), sleeve irrigation aperture (open arrow)
The sleeve adds a small amount of extra girth to the overall phaco probe width. Appreciating this fact can help novices understand why phaco groove strokes are occasionally ineffective at removing lens material. As the phaco tip is used to emulsify lens material, the sleeve may catch the walls of a narrow trench and prevent lens material being removed from the base of the groove. Groove widening may be required if this occurs, (Fig. 11.6).
Fig. 11.6
Phaco probe sleeve. (a) Edges of narrow groove can catch phaco probe sleeve (solid arrows) and prevent removal of lens material at the base of the groove. (b) Widened groove (open arrow) allows access to the lens material
11.1.2 Insertion of Phaco Into the Anterior Chamber
The very first insertion of the phaco prob e into the newly made corneal incision will feel snug (Figs. 11.7, 11.8, 11.9, 11.10, 11.11, and 11.12). If the phaco probe is removed from the eye, further attempts at insertion will be comparatively more straightforward.
Fig. 11.7
The phaco tip and forceps are poised ready for insertion adjacent to corneal wound. Small amount of blood noted near wound (open arrow)
Fig. 11.8
Forceps used to lift upper lip of the corneal section slightly
Fig. 11.9
As anterior corneal wound lip is lifted insert the phaco tip
Fig. 11.10
Irrigation is started after insertion of the probe has commenced. The ports are still outside of the eye and fluid jets can be seen (arrows)
Fig. 11.11
Attempt to navigate the sleeve past the corneal wound
Fig. 11.12
The forceps can be withdrawn and palmed
Insertion of the phaco into the anterior chamber has been described in Chapter 8. It is worthwhile reviewing the fundamentals to ensure a smooth, efficient insertion technique develops.
The Trainee should expect small amounts of fluid to escape from the anterior chamber on initial attempts. Wash any surface blood away from the vicinity of the corneal incision. Avoid tightly gripping the corneal incision with the forceps as this will cause micro trauma.
The posterior lip can be lightly pressed with the phaco tip to open up the wound during the insertion. Ensure the angle of approach allows the tip to pass through the corneal section and not pushed into the corneal stroma. The metal portion will start to enter the eye.
If the sleeve irrigation ports catch the wound, oscillate the tip in a screwing motion as the probe is inserted. This will help navigate the section. The anterior chamber will inflate accordingly.
Use the available fingers of left hand to support phaco probe during pseudo-groove movements.
Box 11.1 Phaco Probe Insertion Tip
The following insertion tips can be of benefit to novice surgeons:
Ensure that the phaco tip is held close to the corneal wound before any manipulation of the wound occurs. This will decrease the distance travelled when the decision has been made to start insertion of the phaco probe.
Avoid hesitancy during insertion. The anterior chamber will start to collapse if too much time is taken as fluid will leak from the corneal wound.
Once inside the eye, briefly hold the tip in the safe zone. This pause allows the surgeon to make any necessary adjustments to the probe grip. It also allows the anterior chamber to fully inflate and provides a moment for the novice surgeon to decide on the next step.
The section is a self-sealing wound and needs to be opened slightly to allow the smooth insertion of the phaco tip. Using an instrument to lift the section can make it easier.
The sleeve (irrigation openings) can catch on the corneal section. A slight rotary screwing motion can aid the passage of the tip into the anterior chamber. Use the forceps if needed to help open the wound if this occurs.
The posterior lip of the corneal wound can be depressed slightly to further open the wound and aid rapid probe insertion. A small amount of downward pressure on the posterior lip can be applied using the phaco probe as it is inserted.
Some surgeons prefer to enter the eye with the phaco tip bevel down and then rotate back to the primary position once inside the eye. This is a personal choice, but this technique requires an extra step of manipulation and handling to return the probe back to the primary position once inside the eye. The Trainer will help decide which method to use.
The foot pedal sequence is important:
Briefly irrigate the eye to wet the ocular surface and ensure a good corneal view. This reduces the need to ask for drops to be applied to the corneal surface during insertion. Under topical anesthesia, drops can cause inadvertent sudden ocular movement or an attempt by the patient to close their eye. This lid squeezing may cause the globe to rotate upwards if a strong Bells’ Phenomenon is present. Brief irrigation will provide an indication of whether the patient may react to any drops applied.
Before tip insertion commences, ensure no irrigation (and definitely no aspiration) is applied. This ensures the cornea is not obscured by fluid. Instead, commence irrigation, during or after placement of the phaco tip into the wound and advancement into the anterior chamber. Aspiration should be avoided to prevent inadvertent iris damage. Listen to the machine noise to help determine the foot setting used.
Sudden rapid insertion of the phaco tip can occur as the sleeve navigates the corneal section. The surgeon should be prepared to stop pushing and pull the probe back to prevent lens or iris damage.
11.1.3 Palming of Forceps
As soon as the phaco probe is inside the eye the forceps can be palmed (see Chap. 7).
There is no requirement to insert a second instrument at this stage and the free fingers of the non-dominant hand can be used to support and steady the phaco probe. Some surgeons may prefer to insert the second instrument before any sculpting is attempted, (this will depend on the Trainer’s preference). Novice surgeons are advised to only introduce the second instrument once the initial trench has been sculpted. This allows a smooth transition between insertion, pseudo-groove and a true groove. Furthermore, without the second instrument in situ, the novice surgeon can concentrate on obtaining a groove of the correct depth without the temptation to use the second instrument and move to the rotation stage too quickly. The caveat to this is that, in situations where the eye is moving excessively, the second instrument may be introduced early to keep the eye steadier during the initial groove. Alternatively, forceps could be used to hold the side port. In practice this is rarely needed.
11.1.4 Pseudo-Groove
A pseudo-groove probe movement is a practice warm up for subsequent grooving. After insertion into the anterior chamber the probe is moved forward and backwards over the lens capsule surface without the phaco tip touching anything (movement without phacoemulsification). This will ensure the phaco sleeve is not caught on the corneal section. Furthermore, as each corneal wound created may be slightly different, the pseudo-groove allows the surgeon to feel the resistance of probe movement within the corneal section. Once inside the eye, it is recommended that one or two pseudo-grooves are performed as part of standard practice.
11.2 The Phacoemulsification Triad
During phacoemulsification, as the phaco tip is moved along the surface of the lens, the material in contact with the tip will be emulsified. The resistance to the phaco probe movement depends on three interacting factors:
- 1.
The lens material density.
- 2.
The amount of material that is engaged within the mouth of the phaco tip.
- 3.
The amount of phacoemulsification energy applied.
The key to successful lens grooving and trench creation is an understanding of how these three factors interact and how to adapt the surgery accordingly.
Attempting to phacoemulsify too much lens material in a single forward movement within the phaco mouth, will require higher phaco energy to maintain smooth grooving movement (unless the lens is very soft). If the phaco power is insufficient, the tip will be unable to cope with emulsifying the lens material. Consequently, the tip will refuse to cut through the lens and instead cause the whole lens to slightly shift forwards and backwards (lens rocking) as pressure from the phaco is applied and released. This can cause stress on the zonules and inadvertently lead to zonular dehiscence. A shallower bite during the phaco stroke is advised. This allows a thinner, more manageable layer of lens material to emulsify in any one phaco groove movement.
It is common for surgeons to program the phaco machine so that the foot pedal can only trigger up to about 45–60% of the maximum ultrasonic power output of the phaco machine. The pre-set amount chosen by the surgeon is adequate to deal with and emulsify cataracts with a range of densities. If the lens is very dense, and requiring repeated attempts to emulsify a thin layer of lens material, then a higher maximum phaco power should be made available. This can be done before surgery starts, if a higher setting requirement is predicted, or during phaco surgery if unexpected density is noted. For more experienced surgeons, another technique may be preferred in this situation, such as chopping the nucleus.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
