(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_4) contains supplementary material, which is available to authorized users.
Irrigation/aspiration (IA) of residual soft lens cortical material is required to clean the inner surface of the capsule bag before placement of the intra ocular lens (IOL).
The various movements the surgeon is required to make with the IA probe tip are explained in Chap. 2. It is assumed the novice surgeon is familiar viscoelastic removal and IOL insertion. Furthermore, the novice surgeon is expected perform IA probe movements and manipulate the IA probe in the correct trajectory when instructed by the Trainer. Ability to demonstrate foot pedal control of irrigation only verses irrigation combined with aspiration and ability to reflux the material from the IA tip port is recommended.
The following description is for a right-handed surgeon—transposition of instructions will be required for left-handed surgeons. Fundamental IA principles that describe the most common method (coaxial ) are introduced below in a stepwise fashion. Though manual and bimanual techniques are not described, the fundamental principles of aspiration technique remain the same. Recommendations for Trainers are suggested at the end of the chapter.
4.1 Irrigation/Aspiration Fundamentals
4.1.1 Aspiration of Soft Lens Material
The fundamental idea of SLM removal is based on 3 principles :
- 1.
A redundant strip of anterior SLM is aspirated and captured into the IA port (i.e. holding aspiration used).
- 2.
The SLM attachment to the anterior capsule is loosened by pulling and dragging the SLM away from its capsule. This severs the SLM capsule adhesion anchor points on the anterior aspect of the capsule (i.e. peeling aspiration used).
- 3.
The SLM is completely peeled off the posterior capsule by increasing aspiration, fully removing the strip of captured SLM (i.e. foot down aspiration used).
During SLM removal the following questions need to be considered:
- 1.
“Where is SLM adherent or stuck to the capsule?”
- 2.
“Towards which direction does the SLM need to be dragged in order to free it from its capsular bag anchor points?”
It should be noted that the direction of drag required to maximise the area of SLM removal may change as SLM is peeled or fully aspirated. Experienced surgeons will do this automatically, but for novice surgeons the subtle change in IA tip direction may not be appreciated unless pointed out during training.
4.2 Aspiration Zone Terminology
The capsule bag can be divided into five zones that each contains 2–3 clock-hours of SLM. Although experienced surgeons may tackle the SLM zones in any order, it is recommended that novice surgeons remove the SLM in a set order, beginning with zones 1–3 consecutively and finishing with the choice of either zone 4 or 5. It is further recommended that each zone of SLM is removed by moving the IA tip in a particular trajectory (Fig. 4.1).
Fig. 4.1
Soft lens material removal zones. Zones are labelled 1–5, direction of irrigation/aspiration probe tip movement (solid arrows)
For novice surgeons operating under instruction, tackling a fixed order of zones using set IA movements promotes easy identification of each zone, allows a predictable movement pattern within the eye, and ensures the IA tip trajectory is as short as possible. As each case is performed in a repetitive fashion, the controlled movements required for stripping the SLM from each zone is quickly developed. If the Trainer feels a certain area of SLM needs to be removed out of sequence, the novice surgeon can be instructed to tackle the appropriate zone accordingly.
Box 4.1 SLM Aspiration Training Tip
When initially learning IA of the SLM, it is recommended that the Trainer remove all sub-incisional SLM in zones 1, 4 and 5. The novice surgeon can take over and continue to remove the residual zones of SLM in zones 2 and 3, followed by lens insertion and viscoelastic removal. As training progresses, more of the SLM in zones 1, 4 and 5 can be left in situ for the novice to remove. Overall, this modular approach reduces the need for the Trainer take over, facilitating the on going practice of IA movements required until the novice surgeon is ready to attempt the remaining zones. See Videos 4.1 and 4.2.
4.3 Step by Step SLM Zone Instruction
4.3.1 Zone 1
Before entering eye check the irrigation fluid flow works, briefly wet the cornea, and enter the eye with the port-up. Aspiration during insertion of the IA tip should not be applied (listen out for the sound difference generated during irrigation-only compared with that of the aspiration setting). Once inside, pause for a moment in the safe zone with the port-up to allow anterior chamber to inflate fully (Fig. 4.2).
Fig. 4.2
Irrigation/aspiration probe inserted into the eye
Rotate the tip anti-clockwise so that the aspiration port almost faces side-on towards the start of zone 1 . For novices, it is preferable to initially maintain the instrument within the centre of the safe zone until the rotation movement is complete, before moving the IA tip towards zone 1 (Fig. 4.3). For more experienced surgeons, the tip can be rotated into the side on position as it is moved towards zone 1.
Fig. 4.3
Zone 1 soft lens material removal
As the port approaches the capsulorhexis border, commence aspiration and increase it so that the redundant SLM overhanging the capsulorhexis edge is captured into the IA port (i.e. holding aspiration). The SLM will be drawn to the aspiration port in preference to the capsule itself. Movement of the SLM into the IA port should be looked for and recognised (foot down aspiration is avoided as this would allow the port access to unprotected anterior capsule as the redundant SLM is fully removed).
Once a portion of the SLM is captured, the initial aim is to strip the SLM off the anterior portion of the capsule, then the posterior aspect. In order to achieve this, the tip movement should continue in a circular fashion just under the capsule. The IA tip, as it is moved in a circular fashion, will peel off the initial border of zone 1 SLM. It will then continue to peel the remaining wedge of zone 1 SLM as it is moved under the under the capsule and returned to the safe zone. The tip should ideally be port-up by the time it reaches the safe zone. The SLM is peeled off the anterior capsule in a tangential fashion (Fig. 4.4).
Fig. 4.4
Zone 1 soft lens material removal—clockwise movement
A clockwise movement of 2–3 clock-hours is performed as the IA port is rotated back to the port-up position.
During the movement, aspiration is adjusted and increased accordingly (peeling aspiration) in order to continue holding the SLM without fully aspirating it. As the tip is returned to the safe zone the SLM will be held under tension. Additional lateral with or without a wind-on-a-stick movement will increase the dragging effect and continue to peel the SLM off the anterior and part of the posterior capsule (Figs. 4.5 and 4.6).
Fig. 4.5
Zone 1 soft lens material removal—triangular wedge. A triangular wedge of soft lens material is peeled off the anterior aspect of the capsule
Fig. 4.6
Zone 1 soft lens material removal—lateral movement. Lateral movement maintains the soft lens material hold under tension
If the SLM is not quite peeled off the capsule, then additional dragging movements may be required before engaging maximum aspiration. Additional dragging movements are done by making to-and-fro movements with the tip, attempting to grab a new holding point on the redundant, loose SLM. This new, fixed hold can then be used to drag and peel the remaining wedge of SLM off the capsule.
Once an area of SLM has been peeled sufficiently it is the time to apply foot down aspiration to fully aspirate the strip of loose SLM. As soon as the SLM has been fully aspirated, power can be reduced and the tip positioned for Zone 2.
The borders of the missing sector of removed SLM will be identified by two signs:
- 1.
A gap in the anterior SLM red-reflex contrasted by the reflex of the remaining SLM.
- 2.
A wedge-shaped change in red-reflex on the posterior aspect of the capsule (Fig. 4.7).
Fig. 4.7
Red-reflex appreciation post soft lens material removal in zone 1. (a) Colour image, (b) Colour image annotated. Gap (dotted line) in posterior portion of soft lens material (irregular solid line), capsulorhexis (circular solid line)
4.3.2 Zone 2
The IA port should now be now close to the start of zone 2. The SLM is now removed from this region. Start aspiration just before the capsulorhexis edge as the port approaches the SLM. If required, a slight clockwise rotation of the tip just before commencing aspiration may help to ensure the IA port faces the SLM in zone 2. This facilitates capture of zone 2 SLM (Fig. 4.8).
Fig. 4.8
Zone 2 soft lens material removal. Redundant anterior soft lens material over hanging capsulorhexis is captured. The IA port is rotated slightly to face the start of zone 2 soft lens material
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