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Two techniques helpful during cataract extraction with phaco
Hydrodissection frees the cataract from the lens capsule, and hydrodelineation splits it into endonuclear and epinuclear sections.
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Once the capsulorrhexis has been created, it is helpful to use balanced salt solution to loosen and separate the cataract to facilitate its removal. The two primary techniques are hydrodissection and hydrodelineation, both of which are performed using a blunt 27-gauge cannula on a 3-cc syringe filled with balanced salt solution.
 Uday Devgan |
Hydrodissection is performed between the capsule and the cataract cortex to free the adhesions of the cataract from the capsular bag and allow it to rotate fully. Care is taken to place the blunt cannula under the edge of the anterior capsulorrhexis and toward the lens equator. You should stop shy of the lens equator, as you do not want to puncture the lens capsule or damage the zonules. Keep the cannula still so that it forms a tight seal between the capsule edge and the cataract. If you move too much and loosen this seal, the fluid will come back toward you and not go forward.
Next, gently press on the plunger of the syringe to send the balanced salt solution around the posterior aspect of the cataract. You want to see at least one fluid wave propagated around the cataract, and more waves are better. As the waves propagate, they will loosen the cataract from the capsular bag and some fluid may become trapped behind. To release this fluid, use the cannula to gently tap on the center of the nucleus and the fluid will be pushed anterior. The key here is to be gentle so that no undue force is used, as this could cause the capsule to rupture and the nucleus to sublux into the vitreous.
How much force is used? Very little; because the key is slow and steady. To give you an idea of the force used, if you take the 3-cc syringe with the 27-gauge cannula and inject it outside of the eye, it would form a gentle arc of fluid that would extend only a few inches. If your level of force causes the fluid to shoot across the room, you are being much too forceful. This requires a steady hand and a good sense of fluid control.
Hydrodelineation is performed to separate the endonucleus from the epinucleus. The central endonucleus is of a higher density and requires more ultrasound energy to remove, whereas the epinuclear shell is softer and easier to remove. This is an optional step that is performed with the idea that the epinuclear shell can act to protect the posterior capsule during phacoemulsification of the endonucleus. Many surgeons do not perform this step and instead prefer to remove the entire nucleus without separating it into these layers.
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Images: Devgan U |
To prevent the fluid from the cannula from going between the capsule and the cataract, which was already performed during hydrodissection, the tip of the cannula should be placed within the edge of the capsulorrhexis and not beyond it. Dig the tip of the cannula into the nuclear material while keeping it within the confines of the 5-mm capsulorrhexis. This will allow proper hydrodelineation and a successful fluid wave will result in the “golden ring” appearance at the area of separation.
Once the cataract has been freed from the capsule with hydrodissection and split into endonuclear and epinuclear sections with hydrodelineation, we are ready to perform nucleus removal using the ultrasound energy from the phaco probe.
For more information:
- Uday Devgan, MD, FACS, is in private practice at Devgan Eye Surgery in Los Angeles, Beverly Hills, and Newport Beach, California. Dr. Devgan is Chief of Ophthalmology at Olive View UCLA Medical Center and an Associate Clinical Professor at the Jules Stein Eye Institute at the UCLA School of Medicine. Dr. Devgan can be reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; 800-337-1969; fax: 310-388-3028; e-mail: devgan@gmail.com; Web site: www.DevganEye.com. Dr.Devgan is a consultant to Abbott Medical Optics and Bausch & Lomb, and is a stockholder in Alcon Laboratories and formerly in Advanced Medical Optics.