Ординатура / Офтальмология / Английские материалы / Modern Cataract Surgery_Kohnen_2002

Fig. 4. Start of large diameter anterior capsulectomy.

Fig. 5. Completion of anterior capsulectomy.

optical zone will correct 1 dpt of astigmatism and two 2-mm incisions will correct 2 dpt of astigmatism in a cataract age patient. One 3-mm incision will correct 2 dpt, and two 3-mm incision 4 dpt. One can combine a 3-mm and 2-mm correcting 3 dpt. Larger amounts of astigmatism can also be corrected utilizing the Arc-T nomogram. Depending on the age of the patient, one can correct up to 8 dpt of astigmatism with two 90° arcs. Many surgeons have moved to a more peripheral corneal limbal arcuate incision, but Dr. Lindstrom favors the 7–8 mm optical zone because of his years of experience with this approach. There certainly is a variation in response, but there have not been any significant induced complications with this approach. The outcome goal is 1 dpt or less of astigmatism in the preoperative axis. It is preferable to undercorrect rather than overcorrect. The key in astigmatism surgery is ‘axis, axis, axis’. If one is not careful in preoperative planning and the incision is placed more than 15° off axis, one is better avoiding this approach.

The anterior chamber is constituted with a viscoelastic. Our studies have not found any significant difference between one viscoelastic or another in regard to postoperative endothelial cell counts. Occucoat has proved be an excellent viscoelastic which can also be utilized to coat the epithelial surface during surgery. This eliminates the need for continuous irrigation with BSS. It gives a very clear view. It is also economically a good choice in most settings. Amvisc Plus also works well and we can obtain 0.8 cm3 of it at a very fair price.

Next a relatively large diameter continuous tear anterior capsulectomy is fashioned (fig. 4, 5). This can be made with a cystotome or forceps. The optimal size is 5.0–6.0 mm in diameter and inside the insertion of the zonules (usually at

Fig. 6. Hydrodissecting the nucleus out of the capsular bag (tilt).

Fig. 7. Rotation of the nucleus toward the incision.

7 mm). Larger is better than smaller, as there is less subcapsular epithelium and thus lower risk of capsular opacification. Additionally, a larger capsulorhexis makes for an easier cataract operation. With this technique there has not been any change in the incidence of intraocular lens decentration. With some intraocular lenses the capsule will seal down to the posterior capsule around the loops rather than be symmetrically placed over the anterior surface of the intraocular lens. These eyes do extremely well and this might be preferable to having the capsule anterior to the optic. This is also certainly a controversial position.

Hydrodissection is then performed utilizing a Pearce hydrodissection cannula on a 3-cm3 syringe filled with BSS. Slow continuous hydrodissection is performed gently lifting the anterior capsular rim until a fluid wave is seen. At this point irrigation is continued until the nucleus tilts on one side, up and out of the capsular bag (fig. 6). If one retracts the capsule at approximately the 7:30 o’clock position with the hydrodissection cannula, usually the nucleus will tilt superiorly. If it tilts in another position, it is simply rotated until it is facing the incision (fig. 7).

Once the nucleus is tilted some additional viscoelastic can be injected under the nucleus pushing the iris and capsule back. Also, additional viscoelastic can be placed over the nuclear edge to protect the endothelium. The nucleus is emulsified from outside-in while supporting the nucleus in the iris plane with a second instrument, such as a Rhein Medical or Storz Lindstrom Star or Lindstrom Trident nucleus rotator (fig. 8). Once half the nucleus is removed, the remaining one half is tumbled upside-down and approached from the opposite pole (fig. 9). Again, it is supported in the iris plane until the emulsification is

Fig. 8. Phacoemulsification in the iris plane.

Fig. 9. Tumbling and phacoemulsification of remaining half nucleus.

completed (fig. 10). Alternatively the nucleus can be rotated and emulsified from the outside edge in, in a carousel or cartwheel type of technique. Finally, in some cases, the nucleus can be continuously emulsified in the iris plane if there is good followability until the entire nucleus is gone.

This a very fast and very safe technique, and as mentioned before, it is a modification of the iris plane technique taught by Richard Kratz, MD, in the late 1970s and 1980s. It is basically ‘back to Kratz’ with help from Brown and Maloney in the modern phacoemulsification, capsulorhexis, hydrodissection and viscoelastic era. Surgery times now range between 5 and 10 min with this approach rather than 10–15 min for endocapsular phacoemulsification. In addition, our capsular tear rate has now gone under 1%. Therefore, we find this technique which to be easier, faster and safer. It is true that in this technique the phacoemulsification tip is closer to the iris margin and also somewhat closer to the corneal endothelium. There is, however, a significantly greater margin of error in regard to the posterior capsule. Care needs to be taken to position the nucleus away from the corneal endothelium and away from the iris margin when utilizing this approach.

If the nucleus does not tilt with simple hydrodissection, it can be tilted with viscoelastic or a second instrument such as a nuclear rotator, Graether collar button or hydrodissection cannula.

When utilizing this approach of phacoemulsification with the Storz Premier instrument, we utilize a vacuum of 60 mm Hg and an anterior chamber maintainer pressure of 60 mm Hg. We favor the Storz microflow plus needle with a 30° bevel.

Fig. 10. Completion of phacoemulsification.

Fig. 11. Irrigation and aspiration of subincisional cortex with right-angled tip.

When utilizing a peristaltic machine, a slightly higher vacuum in the range of 80–100 mm Hg is used. It is best to maintain a relatively high bottle with some overflow of fluid. Again a 30° bevel needle is appropriate for this approach. When utilizing tilt and tumble, very high vacuum settings are not necessary and may be inappropriate. The reason for this is that the iris margin is in the vicinity of the phacoemulsification tip, and it is possible to core through the nucleus and aspirate the iris margin if very high vacuums are utilized.

The dual function Storz Millennium™ is also excellent for all cataract techniques including ‘tilt and tumble’. The vacuum is set with a range of 60–100 mm Hg and the ultrasound power from 10 to 50% with the Storz Millennium™. The foot pedal is arranged such that there is surgeon control over ultrasound on the vertical or pitch motion of the foot pedal, and then on the yaw or right motion foot pedal, there will be vacuum control. This allows very efficient emulsification, and the Millennium™ is currently our preferred machine. The microflow plus needle with a 30° angle tip works well with the Millennium™.

Following completion of nuclear removal, the cortex is removed with the irrigation aspiration hand piece. We prefer a 0.3-mm tip and utilize the universal hand piece with interchangeable tips. A curvilinear tip is used for most cortex removal. Subincisional cortex can be aspirated with a Lindstrom right-angle sand-blasted tip currently manufactured by Rhein and Storz (fig. 11). If there is significant debris or plaque on the posterior capsule, one can attempt some polishing and vacuum cleaning but not so aggressively as to risk capsular tears. Many times there is an unexpected small burr or sharp defect on the I&A tip which results in a capsular tear after a case that was otherwise well done.

Fig. 12. Injection of intraocular lens into capsular bag.

Fig. 13. Posterior chamber lens seated in capsular bag.

The anterior chamber is reconstituted with viscoelastic and the intraocular lens is inserted utilizing an injector system (fig. 12, 13). We prefer the 3-piece silicone lenses which are injectable through a 3-mm incision. In select cases an acrylic implant is chosen, although with a cross-action folder this requires enlargement of the incision. One can inject the acrylic lens with care through a Bartelt injector, but proper technique is necessary or the loops can be damaged.

Excess viscoelastic is removed with irrigation aspiration. Pushing back on the intraocular lens and slowly turn the irrigation aspiration to the right and left two or three times allows a fairly complete removal of viscoelastic under the intraocular lens.

We favor injection of a miotic and tend to prefer carbachol over miochol at this time, as it is more effective in reducing postoperative intraocular tension spikes and has a longer duration of action. It is best to dilute the carbachol 5:1, or one can obtain an excessively small pupil which results in dark vision for the patient at night for 1–2 days. The anterior chamber is then refilled through the counter-puncture and the incision is inspected. If the chamber remains well constituted and there is no spontaneous leak from the incision, wound hydration is not necessary. If there is some shallowing in the anterior chamber and a spontaneous leak, wound hydration is performed by injecting BSS peripherally into the incision and hydrating it to push the edges together. We suspect that within a few minutes these clear corneal or posterior limbal incisions seal, much as a LASIK flap will stick down, through the negative swelling pressure of the cornea and capillary action. It is important to leave the eye slightly firm at 20 mm Hg or so to reduce the side effects of hypotony and also help the internal valve incision appropriately seal.

At completion of the procedure another drop of antibiotic, steroid and nonsteroidal, is placed on the eye. Additionally, one drop of an antihypertensive such as Betagan or Alphagan is applied to reduce postoperative intraocular tension spikes.

Postoperative Care

No patch is routinely utilized for the topical and intracameral approach. If a miniblock of the lids has been performed, this will wear off in 30–45 min, and there is usually adequate lid function for a normal blink at the completion of the procedure. Patients are advised that they will have some erythropsia, meaning they will see a pink after image for the rest of the day, but usually this will resolve by the next morning. They are also told that their vision may be a little dark at night from the miotic, and not to be concerned if they wake up at night and their vision seems dimmer.

The patient is seen on the first day postoperative and then at approximately 2–3 weeks postoperative. At this time a refraction, slit lamp, and funduscopic examination is performed. If there is no inflammation, patients are seen again 1 year postoperative. If at 3 weeks there is still persistent inflammation, additional postoperative anti-inflammatory medications are recommended, and the patient is asked to return again at 2–3 months postoperative.

Topical antibiotic, steroid and nonsteroidal, are utilized twice a day, usually requiring a 5-cm3 bottle and 3–4 weeks of therapy. Occasionally a second bottle of steroid and nonsteroidal is necessary if flare and cell persist at the 3-week examination. There are minimal restrictions, including a request that there be no swimming and no very heavy lifting for 2 weeks. Many patients are given halfglasses the first postoperative day allowing functional vision at distance and near. We consider the ideal postoperative refractive spherical equivalent for a monofocal lens to be 0.62 dpt with 0.50 dpt of astigmatism in the same axis as existed preoperatively. Most patients can see 20/30 and J3 with this type of correction. Monovision can be utilized in the appropriate settings. Good results can also be obtained with the Allergan ARRAY multifocal intraocular lens. In this setting we target plano to 0.25 dpt with minimal astigmatism.

The second eye is done at 1 month or greater postoperatively except in rare situations. Any YAG lasers are deferred for 90 days in order to allow the blood aqueous barrier to become intact and capsular fixation to be firm.

Conclusion

We hope other surgeons will find this approach to cataract surgery useful. These techniques must be personalized, and every surgeon will find that slight

variations in technique are required to achieve optimum results for their own individual patients in their own individual environment. Continuous efforts at incremental improvement result in meaningful advances in our ability to help the cataract patient obtain rapid, safe, visual recovery following surgery.

Dr. Richard L. Lindstrom, Minnesota Eye Consultants PA,

710 East 24th Street, Suite 106, Minneapolis, MN 55404 (USA)

Tel. 1 612 813 3633, Fax 1 612 813 3601, E-Mail rllindstrom@mneye.com

a manipulation. For this reason, Koch [7] suggested a variation of the technique called stop and chop. Both Nagahara’s technique and Koch’s modified technique carry the advantage of tackling hard nuclei without having to resort to very high-power levels and long ultrasound time.

In this work, we present the anterior chamber phacoemulsification technique (phaco-out) as an option for managing such problematic cases, and compare its safety and effectiveness to that of endocapsular phacoemulsification using the stop and chop technique.

Patients and Methods

We performed this prospective pilot study on 30 eyes of 15 patients with bilateral cataract (8 females and 7 males), with an average age of 68 5.38 (range 62–79) years. Patients were selected from our outpatient clinic. The inclusion criteria of the selected patients were: older than 60 years with senile cataract, round regular dilatable pupil (up to at least 6.00 mm), and a visual acuity of 0.32 (20/63) or more. We excluded patients who were younger than 60 years, had complicated cataract, pseudoexfoliation syndrome, other ocular pathology, diabetes mellitus, an endothelial cell count 1,800, and their pupil not being able to reach 6.00 mm of dilatation. Also we excluded patients with the following intraoperative complications: rupture of the posterior capsule, pseudoexfoliation syndrome, and subluxated lens.

Each patient was preoperatively evaluated, and the ocular examination included: gonioscopy, B-scan biometry, and anterior chamber depth estimation by an Ophthasonic Ultrasonic Biometer (Tecknar Inc., St. Louis, Mo., USA), applanation Goldmann tonometry (Haag-Streit, Bern, Switzerland) and keratometry. The spectacle best-corrected visual acuity was estimated in all patients as well as PAM.

A corneal endothelial study of the central cornea was performed by the same physician using a Konan SP5500 contact endothelial cell meter, and cell density, hexagonality, and the coefficient of variation were all documented. At each examination, 2–3 specular microscopic images (an area of 500–1,000 m2) of the central portion of each cornea were taken using video specular endothelioscopy. The images were analyzed after digitization by a Konan KC-87 A image analysis system. For each cornea, 100–150 cells were digitized and analyzed using the morphometry program of the software. Cell density (cells/mm2) was calculated automatically by the computer Cell Analyzer VER 4.00 (Konan Camera Research Institute, Inc., Hyogo, Japan).

Ocular inflammation was assessed using a Kowa laser flare meter (LFCM-1000; Kowa Co. Ltd, Tokyo, Japan) to evaluate the amount of postoperative subclinical inflammation.

Surgical Procedure

Bilateral simultaneous phacoemulsification was performed in the 30 eyes of the 15 patients included in this study using the Legacy 2000 phaco machine (Alcon, Forth Worth, Tex., USA) by the same surgeon. For each patient one eye was operated upon using the phaco-out technique, and the other eye underwent phaco stop and chop technique. The mean nuclear hardness in the phaco stop and chop group was 2.8 0.68 (range 1.5–4.0) and in the phaco-out group was 2.63 0.67 (range 1.5–4.0), with no statistically significant difference between the two groups (p 0.502, independent sample t-test).

The procedure was performed under topical anesthesia using lidocaine 2% (Braun, Barcelona, Spain). A corneal incision was made at 12 o’clock using a 3.2-mm phaco-slit blade (Sharpoint, Surgical Specialities Corp., Reading, Pa., USA). Viscoelastic materials, HPMC and Viscoat (Alcon) were injected in the anterior chamber followed by performing a paracentesis using a 1-mm MVR blade (Sharpoint). Capsulorhexis (about 6 mm in diameter) was then performed using a capsulorhexis forceps (Katena, Denville, N.J., USA). Hydrodissection of the nucleus using a J-hooked and a straight 25-gauge cannula (Sincoe, ASICO, Westmont, Ill., USA) is then performed.

Phaco Stop and Chop Technique. This begins with a groove, as though the surgeon was preparing for Sheperd’s cross nucleofracture. This produces a space for U/S tip and the hook, which will be able to fracture the nucleus into two parts, using a phaco power of 100%, and a vacuum of 60 mm Hg. At this point, the surgeon stops, rotates the nucleus 90°, and changes the machine parameters; the vacuum is increased to 400 mm Hg and the phaco power is changed to 60% in a pulse mode. The surgeon fixes the lower half of the nucleus with the U/S tip, and a crack is created with a chopper instrument (Katena). A number of fragments result, which can be easily mobilized from the capsular bag to be emulsified.

Phaco-Out Technique. Excess hydrodissection is performed. The corneal endothelium is protected using abundant viscoelastic material, HPMC and Viscoat (Alcon). A Sinisky hook (Katena) and a fine blunt-ended spatula are used to deliver the nucleus into the anterior chamber. With the vacuum set at 400 mm Hg and the ultrasound power at 60%, the nucleus is then approached, with a 30° phaco tip, at the equator of one sector removing first the superficial layer, then the intermediate part, and eventually the deep portion. Using the Sinisky hook, the nucleus is rotated 90–180° in order to fragment another sector, and rotated again to remove further sectors, thus reducing progressively the nuclear volume. This technique will prevent early fragmentation of the nucleus, which might wander around the anterior chamber with possible contact with the endothelium. Throughout the procedure, the second instrument is always pushing the nucleus backwards preventing any possible contact with the back of the cornea.

The Acrysoft MA30 intraocular lens (Alcon) was implanted in 11 patients (22 eyes) and the AMO Sensar AR40 (Allergan, Irvine, Calif., USA) was implanted in 4 patients (8 eyes).

A single 10/0 Nylon suture (Alcon) is used to close the corneal incision followed by intracameral injection of Curoxima 2% antibiotic (Glaxo-Wellcome, Burgos, Spain).

Postoperative Treatment

All the patients followed a regimen of topical antibiotic trimethoprim-sulfamethoxazole (Oftalmotrim, Alcon) 4 times a day for 2 weeks, and 2 times a day for another 2 weeks, diclofenac sodium (Voltaren; Ciba Vision, Barcelona, Spain) 4 times a day for 2 weeks, and 2 times a day for another 2 weeks and dexamethasone 2% (Maxitrol, Alcon) 4 times a day for 1 week, 3 times a day for 1 week, 2 times a day for another week, and 1 time a day for 2 more weeks.

Postoperative Follow-Up

All the patients fulfilled a follow-up period of 3 months. The first visit was 3 days postoperatively, then at 2 weeks, 1 month and 3 months postoperatively. Every postoperative examination included slit lamp biomicroscopy, uncorrected and best-corrected visual acuity, corneal pachymetry and laser flare cell meter (LFCM-1000; Kowa Co. Ltd). Endothelial