Contents
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Hydrodissection |
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Technique |
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Hydrodelineation |
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Completion of the Procedure |
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Conclusions |
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CHAPTER HIGHLIGHTS |
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Hydrodissection
Hydrodissection of the nucleus in cataract surgery has traditionally been perceived as the injection of fluid into the cortical layer of the lens under the lens capsule to separate the lens nucleus from the cortex and capsule.[1] With increased use of continuous curvilinear capsulorrhexis[2,][3] and phacoemulsification in cataract surgery, hydrodissection became a very important step to mobilize the nucleus within the capsule for disassembly and removal.[4–8] Following nuclear removal, cortical cleanup proceeded as a separate step, using irrigation and aspiration handpieces.
Fine[9] has previously described cortical cleaving hydrodissection, which is a hydrodissection technique designed to cleave the cortex from the lens capsule and thus leave the cortex attached to the epinucleus. Cortical cleaving hydrodissection usually eliminates the need for cortical cleanup as a separate step in cataract surgery by phacoemulsification, thereby eliminating the associated risk of capsular rupture.
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Technique
A small capsulorrhexis, 5–5.5 mm, optimizes the procedure. The large anterior capsular flap makes this type of hydrodissection easier to perform. The anterior capsular flap is elevated away from the cortical material with a 26-gauge blunt cannula (e.g., Katena Instruments No. K7-5150) before hydrodissection (Figures 15-1–15-3). The cannula maintains the anterior capsule in a tented-up position at the injection site near the lens equator. Irrigation before elevation of the anterior capsule should be avoided because it will result in transmission of a fluid wave circumferentially within the cortical layer, hydrating the cortex and creating a path of least resistance that will disallow later cortical cleaving hydrodissection (Figure 15-4). Once the cannula is properly placed and the anterior capsule is elevated, gentle, continuous irrigation results in a fluid wave that passes circumferentially in the zone just under the capsule, cleaving the cortex from the posterior capsule in most locations. When the fluid wave has passed around the posterior aspect of the lens, the entire lens bulges forward because the fluid is trapped by the firm equatorial cortical-capsular connections (Figures 15-5 and 15-6). The procedure creates, in effect, a temporary intraoperative version of capsular block syndrome as seen by the enlargement of the diameter of the capsulorrhexis. At this point, if fluid injection is continued, a portion of the lens prolapses through the capsulorrhexis. However, if the capsule is decompressed before prolapse by depressing the central portion of the lens with the side of the cannula in a way that forces fluid to come around the lens equator from behind (Figures 15-7 and 15-8), the cortical-capsular connections in the capsular fornix and under the anterior capsular flap are cleaved. The cleavage of cortex from the capsule equatorially and anteriorly allows fluid to exit from the capsular bag via the capsulorrhexis, which constricts to its original size, and mobilizes the lens in such a way that it can spin freely within the capsular bag. Repeating the hydrodissection and capsular decompression starting in the opposite distal quadrant may be helpful. Adequate hydrodissection at this point can be demonstrated by the ease with which the nuclear–cortical complex can be rotated by the cannula.
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Figure 15-1 Placement of the cannula under the anterior capsulorrhexis in one of quadrants, elevating the capsule. |
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Figure 15-2 Cortical cleaving hydrodissection. A, In the original technique, the cannula is passed inferiorly, with tenting up of the anterior capsule before injection of fluid. B, The alternative technique described by Steinert uses a 180° Binkhorst cannula to direct the initial fluid wave superiorly. The cannula is rotated to elevate the anterior capsule and to direct the fluid wave between the capsule and the cortex. |
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Figure 15-3 A, In cortical cleaving hydrodissection, the fluid wave passes between the capsule and cortex. B, In conventional hydrodissection, the natural fluid cleavage plane is between the cortex and epinucleus. |
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Figure 15-4 As the fluid is injected, a posterior fluid wave is created. |
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Figure 15-5 Enlargement of capsulorrhexis as seen following second cortical-cleaving hydrodissection, fluid wave placed in the opposite distal quadrant just before decompression of the capsular bag. |
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Figure 15-6 As cortical-cleaving hydrodissection proceeds, fluid is trapped posteriorly, with anterior displacement of the lens in the capsular bag. |
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Figure 15-7 Return of capsulorrhexis to its original size following decompression of the bag. |
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Figure 15-8 Posteriorly loculated fluid is decompressed by downward pressure on the lens with the cannula. Trapped fluid then advances around the equator, releasing equatorial cortical-capsular adhesions. |
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Hydrodelineation
Hydrodelineation is a term first used by Anis[10] to describe the act of separating an outer epinuclear shell or multiple shells from the central compact mass of inner nuclear material, the endonucleus, by the forceful irrigation of fluids (balanced salt solution) into the mass of the nucleus.
Our technique uses the same hydrodissection cannula as previously described. The cannula is placed in the nucleus, off center to either side, and directed at an angle downward and forward towards the central plane of the nucleus. When the nucleus starts to move, the endonucleus has been reached; it is not penetrated by the cannula. At this point, the cannula is directed tangentially to the endonucleus, and a to-and-fro movement of the cannula is used to create a tract within the nucleus. The cannula is backed out of the tract approximately halfway (Figure 15-9), and a gentle but steady pressure on the syringe allows fluid to enter the “empty” distal tract without resistance. Driven by the hydraulic force of the syringe, the fluid will find the path of least resistance, which is the junction between the endonucleus and the epinucleus, and flow circumferentially in this contour (Figure 15-10). Most often, a circumferential golden ring will be seen outlining the cleavage between the epinucleus and the endonucleus. Sometimes the ring will appear as a dark circle rather than a golden ring.
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Figure 15-9 Hydrodelineation is performed by determining the natural cleavage plane between the nucleus and epinucleus. A, Blunt-tipped cannula is advanced as deeply as possible, thereby riding across the tops of the firm nucleus. B, Cannula is advanced inferiorly. C, Cannula is then partially withdrawn within the tract. Sufficient cannula length is embedded in the lens material to trap fluid to be injected, but the open tract created allows the fluid pressure to seek out the natural cleavage plane between the inner nucleus and the middle epinuclear layer. |
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Figure 15-10 Complete hydrodelineation is obtained. If the pupil is widely dilated relative to the size of the nucleus, a “golden ring” is seen because of the microscope light reflex. |
Occasionally, an arc will result and surround approximately one quadrant of the endonucleus. In this instance, creating another tract the same depth as the first but ending at one end of the arc, and injecting into the middle of the second tract, will extend that arc (usually another full quadrant). This can be repeated until a golden or dark ring verifies circumferential division of the nucleus.
For very soft nuclei, the placement of the cannula allows creation of an epinuclear shell of variable thickness. The cannula may pass through the entire nucleus if it is soft enough, so the placement of the tract and the location of the injection allow an epinuclear shell to be fashioned as desired. In very firm nuclei, one appears to be injecting into the cortex on the anterior surface of the nucleus, and the golden ring will not be seen. However, a thin, hard epinuclear shell is achieved even in the most brunescent nuclei. That shell will offer the same protection as a thicker epinucleus in a softer cataract.
Hydrodelineation circumferentially divides the nucleus and has many advantages. Circumferential division reduces the volume of the central portion of nucleus removed by phacoemulsification by up to 50%. This allows less deep and less peripheral grooving and smaller, more easily mobilized quadrants after cracking or chopping. The epinucleus acts as a protective cushion within which all of the chopping, cracking and phacoemulsification forces can be confined. In addition, the epinucleus keeps the bag on stretch throughout the procedure, making it unlikely that a knuckle of capsule will come forward, occlude the phaco tip, and rupture. More recently, Vasavada has described a technique for hydrodelineation in very hard cataract called “inside-out hydrodelineation.”[11] The nucleus is bowled out and then fluid is injected from inside the bowl outward. This then allows endonuclear rotation and chopping of the peripheral endonucleus bowl and removal of the epinucleus in the usual manner.
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Completion of the procedure
After evacuation of all endonuclear material, the epinuclear rim is trimmed in each of the three quadrants (Figure 15-11), mobilizing cortex as well in the following way. As each quadrant of the epinuclear rim is rotated to the distal position in the capsule and trimmed, the cortex in the adjacent capsular fornix flows over the floor of the epinucleus and into the phaco tip (Figure 15-12). Then the floor is pushed back to keep the bag on stretch until three of the four quadrants of the epinuclear rim and forniceal cortex have been evacuated (Figure 15-13). It is important not to allow the epinucleus to flip too early, thus avoiding a large amount of residual cortex remaining after evacuation of the epinucleus.
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Figure 15-11 Purchase of the epinuclear rim and roof in foot position 2, being pulled central to the capsulorrhexis. The cortical layer is seen superior to the rim and roof of the epinuclear shell. |
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Figure 15-12 Following trimming of the initial purchase of the rim and roof in foot position 3, one can see the cortex flow over the floor and into the tip, removing it from that same quadrant. |
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Figure 15-13 Repositioning the floor of the epinucleus after rim and roof of the epinuclear shell have been trimmed and the cortex has been evacuated from the third epinuclear quadrant. |
The epinuclear rim of the fourth quadrant is then used as a handle to flip the epinucleus (Figures 15-14 and 15-15). As the remaining portion of the epinuclear floor and rim is evacuated from the eye, 70% of the time the entire cortex is evacuated with it (Figure 15-16).[12] Downsized phaco tips with their increased resistance to flow are less capable of mobilizing the cortex because of the decreased minisurge accompanying the clearance of the tip when going from foot position 2 to foot position 3 in trimming of the epinucleus. After the intraocular lens is inserted, these strands and any residual viscoelastic material are removed using the irrigation–aspiration tip, leaving a clean capsular bag.
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Figure 15-14 Initiating the flipping maneuver of the residual epinucleus using the fourth quadrant of epinuclear rim and shell. |
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Figure 15-15 Aspiration of residual epinuclear and cortical envelope. |
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Figure 15-16 Capsular bag is clear of cortex, except for a single strand to the right following flipping and evacuation of the residual epinucleus. |
If there is cortex still remaining following removal of all the nucleus and epinucleus, there are three options:
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The phacoemulsification handpiece can be left high in the anterior chamber while the second handpiece strokes the cortex-filled capsular fornices. Often, this results in floating up of the cortical shell as a single piece and its exit through the phacoemulsification tip (in foot position 2) because cortical cleaving hydrodissection has cleaved most of the cortical capsular adhesions. |
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If the surgeon wishes to complete cortical cleanup with the irrigation–aspiration handpiece before lens implantation, the residual cortex can almost always be mobilized as a separate and discrete shell (reminiscent of the epinucleus) and removed without ever turning the aspiration port down to face the posterior capsule (see Figure 15-15). |
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The final option is to viscodissect the residual cortex by injecting the viscoelastic through the posterior cortex onto the posterior capsule. We prefer the dispersive viscoelastic device chondroitin sulfate-hyaluronate [Viscoat]. The viscoelastic material spreads horizontally, elevating the posterior cortex and draping it over the anterior capsular flap (Figure 15-17). At the same time the peripheral cortex is forced into the capsular fornix (Figure 15-18). The posterior capsule is then deepened with a cohesive viscoelastic device [e.g., Provisc] and the IOL is implanted through the capsulorrhexis, leaving the anterior extension of the residual cortex anterior to the IOL (Figure 15-19). |
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Figure 15-17 Residual cortex can be aspirated after intraocular lens insertion. The first step is to carefully instill a viscoelastic agent under the residual cortex. |
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Figure 15-18 As the viscoelastic agent fills the capsular bag, tags of remaining cortex are brought anteriorly, draping over the anterior capsule. |
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Figure 15-19 After the intraocular lens (IOL) is placed in the capsular bag, residual cortex is then anterior to the IOL optic. |
Removal of residual viscoelastic material accompanies mobilization and aspiration of residual cortex anterior to the IOL (Figure 15-20), which protects the posterior capsule, leaving a clean capsular bag.
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Figure 15-20 Irrigation–aspiration tip can now access the remaining cortex and successfully aspirate the cortex while the intraocular lens remains within the capsular bag. |
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Conclusions
In summary, the lens can be divided into an epinuclear zone with most of the cortex attached and a more compact central nuclear mass. The central portion of the cataract can be removed by any endolenticular technique, after which the protective epinucleus is removed with all or most of the cortex attached. In most cases, irrigation and aspiration of the cortex as a separate step are not required, thereby eliminating that portion of the surgical procedure and its attendant risk of capsular disruption. Residual cortical cleanup may be accomplished in the presence of a posterior chamber IOL, which protects the posterior capsule by holding it remote from the aspiration port.
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References
[1]. Faust K.J.: Hydrodissection of soft nuclei. Am Intraocular Implant Soc J 1984; 10:75-77.
[2]. Neuhann T.: Theorie und operationstechnik der kapsulorhexis. Klin Monatsbl Augenheilkd 1987; 190:542-545.
[3]. Gimbel H.V., Heuhann T.: Development, advantages, and methods of the continuous circular capsulorrhexis technique. J Cataract Refract Surg 1990; 16:31-37.
[4]. Davison J.A.: Bimodal capsular bag phacoemulsification: a serial cutting and suction ultrasonic nuclear dissection technique. J Cataract Refract Surg 1989; 15:272-282.
[5]. Sheperd J.R.: In situ fracture. J Cataract Refract Surg 1990; 16:436-440.
[6]. Gimbel H.V.: Divide and conquer nucleofractis phacoemulsification: development and variations. J Cataract Refract Surg 1991; 17:281-291.
[7]. Fine I.H.: The chip and flip phacoemulsification technique. J Cataract Refract Surg 1991; 17:366-371.
[8]. Fine I.H., Maloney W.F., Dillman D.M.: Crack and flip phacoemulsification. J Cataract Refract Surg 1993; 19:797-802.
[9]. Fine I.H.: Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508-512.
[10]. Anis A.: Understanding hydrodelineation: the term and related procedures. Ocular Surg News 1991; 9:134-137.
[11]. Vasavada A.R., Raj S.M.: Inside-out delineation. J Cataract Refract Surg 2004; 30:1167-1169.
[12]. Fine I.H.: The choo-choo chop and flip phacoemulsification technique. Op Tech Cataract Refract Surg 1998; 1:61-65.