(1)
Newcastle Eye Centre Royal Victoria Infirmary, Newcastle upon Tyne, UK
Even when lens nucleus fragments kept within-the-bag may be adequately separated, individual fragments may resist extraction and subsequent phacoemulsification removal. A variety of factors may be responsible, including: fragment removal that is hindered by adjacent fragments interlocking together; the second instrument inadvertently knocking the fragment off the phaco tip as it is extracted; or the target-fragment colliding with another fragment along the line of movement. The make-a-space principles explained here will aid the surgeon when removing fragments, helping them to avoid the pitfalls listed above.
10.1 Fundamentals: The Lens Fragment
The term ‘target-fragment ’ refers to the selected lens fragment the surgeon intends to extract and phacoemulsify.
A lens fragment is a pyramidal shaped, with an apex and a curvilinear base. At the widest point of the base, each fragment has two shoulders (Fig. 10.1). The base and shoulders remain hidden under the rhexis edge. Once the fragment is embedded on the phaco tip it can be repositioned, rotated and moved about as if it were an extension of the phaco probe .
Fig. 10.1
The lens fragment. (a) Apex (star), shoulder (arrow), base of segment (arrowhead), capsulorhexis outline (dotted line). (b) Embedded fragment can be moved as an extension of phaco probe
10.2 Make-a-Space Principles
10.2.1 Initial Fragment Choice
Once the nucleus has been grooved and spilt into four pieces, it is time to pause for a moment so that the size of all the available fragments may be analysed. In spite of the temptation to try and extract the fragment immediately opposite the phaco probe , it is recommended that the smallest sized fragment is identified instead. Ideally the smallest fragment should be repositioned into the starting position space (directly opposite and in line with the phaco tip). If the smallest fragment is not directly opposite the phaco probe, an attempt should be made to rotate the pieces until it is (Fig. 10.2). The smallest fragment will exhibit the least resistance to extraction. Once the smallest fragment is removed, additional manoeuvring space for the other fragments is created.
Fig. 10.2
Initial fragment choice . (a) Smallest fragment (arrow) is not ideally positioned opposite phaco probe. (b) Smallest fragment is repositioned opposite the phaco probe by rotating fragments (curvilinear arrow)
10.2.2 Fragment Extraction from the Capsule Bag: Unlocking Fragments
Separated nuclear fragment pieces may have sidewalls with irregular contours. When this happens, neighbouring fragments can interlock like pieces of a jigsaw, preventing the free movement of one fragment as it tries to slide past another. Interlocking may occur as separated fragments are pushed into each other, for example during fragment rotation, or whilst cracking the lens nucleus. Unlocking may therefore be required to facilitate the unhindered movement of fragments.
Fragment unlocking is easily performed by placing a second instrument into the gap between fragments and then using that instrument to pull at the proximal the fragment (i.e. pulling it away from the target-fragment to “make-a-space”) (Fig. 10.3). This is a useful technique that can help extract the initial fragment from the capsular bag, whilst at the same time ensuring that the second instrument is kept out of the target-fragment’s intended line of extraction.
Fig. 10.3
Unlocking interlocked fragments —1. (a) Walls of adjacent fragment are interlocked (white star). (b) Potential space (black star) for fragment extraction (arrow) created by unlocking pieces using second instrument to retract proximal fragment
10.2.3 Fragment Extraction from the Capsule Bag: Unlocking Fragments and Moving the Target-Fragment into a Created Lateral Space Before Pulling into a Central Location
In the previous principle, despite unlocking the left hand side of the target-fragment from it neighbour to “make-a- space” the right hand side of the target-fragment can still be interlocked with its neighbouring segment on the opposite side This can potentially hinder its movement during extraction. It is recommended that a space is created using the second instrument as described in principle 2 ‘unlocking fragments’. However, instead of pulling the target-fragment directly into the central area, the trajectory should follow a reverse number seven direction (Fig. 10.4a). If the potential space is to the right hand side of the target-fragment, the then target-fragment manipulation should follow a “normal” number seven direction (Fig. 10.4b). Only a small lateral movement is needed before the fragment should be pulled centrally.
Fig. 10.4
Unlocking interlocked fragments—2. (a) Fragment is moved laterally towards potential space and then pulled into central area using a reverse number seven movement (arrow). (b) Fragment is moved laterally into potential space and then pulled into central area using a number seven movement (arrow)
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