(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_6) contains supplementary material, which is available to authorized users.
Most surgeons perform hydrodissection with the intention of injecting fluid into the potential space between the lens capsule and the nucleus. Cortical cleaving hydrodissection is achieved if the fluid separates the cortical material completely from the capsule, leaving a bare surface after lens removal [1]. Although perfect hydrodissection can reduce the need for subsequent soft lens material (SLM) removal , in practice, the injection of fluid results in the separation of the lens endonucleus and epinucleus from the cortex and capsule [2]. With rear-ended training the Trainee will be familiar with removing this thin layer of SLM that remains attached to the capsule.
The aim of this chapter is to provide the fundamental principles of how to perform hydrodissection, and what clinical signs to recognise. In order to simplify this topic, many actions do not appear in sequence. As a result, a full appreciation of the surgical steps will be only gained after reading the whole chapter.
The aims of hydrodissection are two-fold:
- 1.
To separate the adhesions between the lens nucleus and capsule, ensuring the nucleus is freely mobile during phacoemulsification.
(Poor hydrodissection will result in difficulty when rotating the lens nucleus).
- 2.
To leave a thin, single layer of cortical SLM adherent to the capsule.
6.1 Fundamental Principles and Clinical Signs
6.1.1 Create Space: The Viscoelastic Burp
Following curvilinear capsulorhexis (CCC), the anterior chamber remains filled with residual viscoelastic (Fig. 6.1).
Fig. 6.1
Cross section of anterior chamber. Anterior chamber is filled with viscoelastic (long arrow), lens (star) and capsule outline (arrow) with capsulorhexis performed
Thus, there is minimal room for additional fluid to be injected into the eye. Any attempt to inject more fluid requires more force in order to displace some of the existing viscoelastic material. In order to avoid this, it is recommended that space is created above the lens. Gentle pressure on the posterior lip of the corneal incision causes expulsion of a small amount of viscoelastic (Fig. 6.2). The anterior chamber is not allowed to completely empty during the viscoelastic ‘burp’ (Fig. 6.3).
Fig. 6.2
Cross section of anterior chamber—viscoelastic fluid escape. A small amount of viscoelastic is allowed to escape by cannula pressure on the corneal section (star). Space is created above the lens (arrow)
Fig. 6.3
Viscoelastic burp . (a) Post capsulorhexis completion, (b) posterior corneal incision pressure allows small amount of viscoelastic (arrow) to escape
6.1.2 Adequate Posterior Wave Propagation: Lens Prolapse
By burping viscoelastic, space is created for the lens to shift upwards slightly during hydrodissection. The fluid wave can then propagate circumferentially around the nucleus, usually stopping short of the anterior capsule area, opposite the site of injection. For example, if injecting at 5 o’clock the wave halts underneath the corneal section (Fig. 6.4). This is similar to capsular block syndrome and any subsequent fluid injected will then cause the lens to visibly rise upwards and start to bulge through the capsulorhexis opening. This is an important sign to look for (Fig. 6.5). Lens rise can be anticipated by observing the propagation wave and judging when it has travelled from one side of the lens to the other (see Sect. 1.5).
Fig. 6.4
Propagation of fluid wave. The lens move upward slightly (arrow) as the propagation of fluid (curvilinear arrows) passes beneath it. The wave halts (star) opposite the site of injection
Fig. 6.5
Visible lens prolapse following adequate hydrodissection. Lens (star) starts to prolapse upwards (arrow) into the anterior chamber
It is advisable to observe a definite small upward rise before stopping further fluid injection. Care is required to abruptly stop injecting, otherwise the lens can rapidly prolapse into the anterior chamber.
6.1.3 Adequate Posterior Wave Propagation: Lens Depression
Withdraw the cannula and depress the lens gently at the apical centre with the cannula. As the lens is gently pushed into the bag the fluid wave will continue to propagate around the capsule anteriorly overcoming any equatorial epinucleus cortical adhesion. The lens should be pressed gently near the capsulorhexis edge in various locations to help further promote the small amount of fluid that is trapped posteriorly to propagate anteriorly under the anterior capsule. The red-reflex under the anterior capsule will alter slightly as this additional step is performed.
6.1.4 Where Should Fluid be Injected for Maximum Effect?
Incorrect placement of the hydrodissection cannula can result in poor overall technique. The lens is convex in shape with the apex located centrally. Placing the cannula over the central apex of the lens can hinder upward lens shift during hydrodissection and potentially halt the fluid wave from propagating posteriorly (Fig. 6.6). In view of this, avoid cannula tip placement at the 6 o’clock cardinal point, directly opposite the corneal section (Fig. 6.7).
