Ординатура / Офтальмология / Английские материалы / The Art of Phacoemulsification_Mehta, Alpar_2001

412 THE ART OF PHACOEMULSIFICATION

removal. Using the sandwich method (spatula or wire vectis below, a flat broad blade iris repositor in front, the entire lens or the largest fragment is supported and then slid out of the chamber. Again, viscoelastic is filled and dry aspiration of the residual cortical fragments can be carried out. It is important to do vitrectomy within minimal BSS irrigation but with more of viscoelastic. Subsequently the

IOL is placed on the anterior capsule in the sulcus.

• If the fragments are large, i.e. the break occurred, and the large fragments are showing

signs of an eminent luxation

The method of handling this problem is termed the cruciate technique. A slightly different technique, but essentially similar has also been described by Charles Kelman (1998). All one does is to take two MVR blades (Alcon) and insert them 5.00 mm from the limbus through the conjunctiva and the sclera via the pars plana into the vitreous and out the same way from the opposite side. Place the first one at 7 O’clock position; emerging again at 2 O’clock. The second one is placed at 4 O’clock and emerging at 10 O’clock position. The assumptions being that you are operating at the 12 O’clock position. In case you are operating temporally, change the position of the MVR blades so that they do not interfere with your routine surgery.

Now introduce viscoelastic and then, using dry dissection, first aspirate out all the cortical material, leaving behind only the hard nucleus.Narrow the pupil with Miochol or with pilocarpine 1 percent eyedrops.

The next step is to insert a plastic 3.00 mm wide plastic slide. This slide can be made from the sterile plastic over wrap, which comes with the intraocular implants. Slide it below the nucleus so that it occludes the narrowed pupillary area. Now that the nucleus has been stabilized one can open the chamber and using the sandwich technique remove the fragment, or if the nucleus fragment seems soft and the surgeons very sure of his or her rability, he or she may try to gently phaco the fragment out.

Lower the bottle height to 1/2 meters above the patient’s eye. Reduce flow rate to 12 mm Hg. Minimize the quantity of fluid entering the eye and do a dry phaco using viscoelastic, the BSS being only used to replenish the chamber in case it looks as if it is liable to collapse. This will slow down the pace in the chamber. Reduce your ultrasound energy to pulse phaco with a maximum setting of 40% power. Reduce aspiration rate.

Maneuver the nucleus into the anterior chamber ahead of the iris. Now proceed with a slow phaco using a phaco chop technique. Use minimum ultrasound power. Move slowly. There is no hurry. You should manage to complete the phaco with no difficulty.

Now insert your IOL, preferably foldable. Place it in the anterior chamber. Do not remove the slide yet. Maneuver each of the loops into the sulcus, in front of the anterior capsule. Only then, remove the slide. Gently rinse out the chamber. Inject BSS via the side port and let the viscoelastic gently wash out of the main phaco entry port.

PREVENTION OF COMPLICATIONS AND THEIR MANAGEMENT IN PHACOEMULSIFICATION 413

Remove the MVR blades only as a final step. Done carefully the results are exceptional the next day. The eye is very quiet.

Rupture of the Posterior Capsule, with Hyaloid Face Rupture, with Luxation of Nuclear Material into the Vitreous

Unless the surgeon is very confident of his or her ability to do a good 3 port posterior vitrectomy and to handle a contact lens on the cornea, common sense would dictate

that he does a little anterior vitrectomy, removes, using dry aspiration, as much of the cortical remnants and closes up. It does not make sense to place an IOL,

as it would need to be removed by the retina surgeon when he or she gets the fragment out. The only time it is considered permissible to place the IOL in is when the material that has luxated is soft and the surgeon feels that with a phaco-fragmentor the retina surgeon will get the pieces out. Never try and sweep the vitreous with a vectis as this is almost a guarantee of either a massive retinal detachment with the eye immediately filling up with blood, if accidental retinal touch occurs, or a late detachment due to the gross disturbance of the vitreous at a later date.

There are three ways the retina specialist may choose to remove the lens.

•Using PFC (perfluorocarbon), after doing a full-fledged core vitrectomy, the nucleus can be floated up. Though it looks like a very simple technique, the PFC needs to be completely removed or else a severe reaction ensues and total removal is not within the province of the anterior segment surgeon.

•Following a good three-port vitrectomy, the nucleus is speared and then gradually using a bimanual technique with the light pipe in one hand and a diamondcoated forceps or a spear in the other. The nucleus is gradually lifted to the anterior chamber where it is then removed after opening the chamber.

•In an identical manner, following a vitrectomy, a phacofragmentor is introduced through one port and the lens fragmented in the vitreous itself.

FURTHER READING

1.Mehta KR: When not to do an anterior chamber implant. All India Ophthl Soc Proc 164-65,1986.

2.Mehta KR: Pitfalls encountered in 1500 consecutive posterior chamber implant. All India Ophthl Soc Proc 165-66,1986.

3.Mehta KR: Phacoemulsification cataract extraction with foldable IOLS—first 50 cases. All India Ophthl Soc Proc 56-60,1989.

4.Mehta KR: Posterior capsular capsulorrhexis with shallow core vitrectomy following implantation in paediatric cataracts. All India Ophthl Soc Proc 207-10,1995.

5.Mehta KR: An advanced but simple keratometer for control of postoperative astigmatism. All India Ophthl Soc Proc 122-23,1990.

6.Mehta KR: An analysis of causative factor leading to eye strain caused by computer monitor screens.

All India Ophthl Soc Proc 334-36,1990.

7.Mehta KR: Shelve and shear phacoemulsification. All India Ophthl Soc Proc (Mumbai) 1995.

8.Mehta KR: The prephaco split technique using the contrasplit forceps—a new technique. All India Ophthl Soc Proc, 1998.

414 THE ART OF PHACOEMULSIFICATION

9.Mehta KR: Pupillary dilatation for recalcitrant pupils prior phaco with the new multipoint bicuspid pupil dilatation forceps. All India Ophthl Soc Proc, 1998.

10.Mehta KR: Use of intracameral yellow (Kodak Wratten 59 Filter) Fibreoptic light source for phacoemulsification in dense corneal opacities prior corneal transplantation. All India Ophthl Soc Proc, 1998.

11.Mehta KR: The tripod posterior chamber flexible acrylic implant—the answer to better stability. APIIA Conference, 1997.

12.Mehta KR: Astigmatic control using the new curved laminating keratotomy technique. APIIA Conference, 1997.

13.Mehta KR: The tripod posterior chamber foldable acrylic lens. Proc of SAARC Conference, Nepal, 1994.

14.Mehta KR: Phacoemulsification, the “roller-flip” way for suprahard cataracts—it works great. Proc of SAARC Conference, Nepal, 1994.

15.Mehta KR: Intralenticular phacoemulsification—a new technique. Proc of SAARC Conference, Nepal, 1994.

16.Mehta KR: Management of subincisional cortex in small incision cataract surgery (SICS). Proc of SAARC Conference, Nepal, 1994.

17.Mehta KR: Methylcellulose induced sterile endophthalmitis following phacoemulsification. Proc of SAARC Conference, Nepal, 1994.

18.Mehta KR: Double intraocular lens implantation for high ametropia and for correction of inadvertant remnant ametropia. Proc of SAARC Conference, Nepal, 1994.

19.Mehta KR: Comparison of scleral vs transiridial corneal suspended vs iridial suturing of PC IOL implants with inadequate capsular support. Proc of SAARC Conference, Nepal, 1994.

20.Mehta KR: The new multiport phaco tip for safer, more effective phacoemulsification, with virtually zero capsular damage. Proc of SAARC Conference, Nepal, 1994.

PB THE ART OF PHACOEMULSIFICATION

We can have two types of pupillary capture:

•Without posterior synechiae.

•With posterior synechiae.

PUPILLARY CAPTURE WITHOUT POSTERIOR SYNECHIAE

This type of capture generally appears early after a cataract surgery, when the IOL is not placed in the bag3 and when, due to a trauma, the lens is moved anteriorily to the front of the iris; mainly if the pupil is still dilated. It can occur in cases of IOL scleral fixation, in which the IOL was tilted and part of it can easily move

to the front of the iris.

In cases of old surgeries this type of capture rarely occurs, because the IOL is, somehow, already secured to a structure, be it the posterior or anterior capsule, or to the iris itself; only a special trauma would dislodge the lens from its position. Patients with shallow anterior chambers, or lens with inadequate angulation of the haptics, damaged lenses, lenses not well centered, or placed in an inverted way would be more likely to this occurrence.

These patients rarely notice the problem. The physician makes the diagnosis and depending on the cause, the correct treatment is indicated. In some cases, through light compression maneuvers on the ocular globe guided by the slit lamp images with a half-dilated pupil, one manages to reposition it.1,4,6 If this were not possible, one would have to return it to place by using the technique that will be described later on in this chapter.

PUPILLARY CAPTURE WITH POSTERIOR SYNECHIAE

In the medium or late postoperative period3 of the cataract surgery with IOL implantation, posterior synechiae conducive to pupillary capture may occur.3,5 Such occurrence is becoming rare, but when it happens it deserves a special attention.

The predisposing factors favoring the lens capture are: IOL implantation in children or in the recently operated cases of retina or vitreous, in cases of combined glaucoma and cataract surgery, in cases of uveitis7, in traumas in general, in diabetic patients; in long-lasting surgeries with a lot of wash

of the anterior chamber, in the inadvertent use of toxic substances in the anterior camera, in the not well-positioned lenses, etc.

The signs and symptoms of the IOL capture will depend on the amount of the optical zone that is on the iris, on the time that it has been there, on the IOL attrition on the iris or if it is touching the cornea, and also on the patient’s own inflammatory factors as in the case of decompensated diabetic patients, or in chronic uveitis. By using the slit lamp one can see the lens in

front of the iris. Generally, pigments are found on the lens. And the posterior capsule presents with a certain degree of opacification caused by fibrosis and leading to a decrease in vision. One notices that in the area of the capture the iris is trapped in the posterior capsule. In the recent cases, the iris under the lens is just compressed by it. Over time, the lens chafing on the iris causes the iris tissue to become atrophic, making it more clear and allowing for a sharper visualization of the iris vases.

Over time, hemorrhages in the anterior chamber may occur, leading to a chafing

syndrome and ending up in glaucoma later. In some cases, a certain chronic perikerato hyperemia can occur, with a discreet tyndal.

Another problem that can come up, due to the inflammatory reaction in the iris, is the CME, which causes loss of visual acuity. When a large area of the lens comes forward to the anterior chamber and moves to the periphery, there can be lens chafing on the corneal endothelium due to the normal movement of the eye. Sometimes this chafing is not noticed through the slit lamp and, however, a corneal decompensation starts appearing in that area. If this decompensation is not treated, it can develop into a bullous keratopathy, which will require a corneal transplantation later on. Small asymptomatic captures without any clinical evolution, as well as serious cases with low vision5, even with UGH syndrome, can occur naturally with all the intermediary possibilities. It is very frequent for the patient to have normal vision and yet to complain of some photophobia and an uncomfortable sensation of scratching in the eye at times.

Treatment of the IOLs Captures with Posterior Synechiae

In general, the treatment is conservative because the symptoms, in spite of being uncomfortable, are tolerable and the solution was not very exciting. To avoid using corticoids constantly and increasing the intraocular pressure, nonhormonal antiinflammatory, and sometimes some mild midriatics, is used at night. When there is CME it is naturally treated accordingly. In the most serious cases, demanding an intervention, the solution is to take the patient to the surgery room, to remove the synechiae as much as possible, and to place the lens again in its position. In these eyes, the iris is already atrophied and, when the synechiae are removed, it does not regain movement, ending up with a new synechia over time. In 1998, we presented in a film in San Diego, a technique that has been giving great results. It is a simple technique that can be used in the consulting room. And for this reason, even in the simplest cases which did not require any intervention some time ago, today when we do it the patient reports an improvement in his ocular comfort. Amazing results have been achieved in more serious cases in which the vision is quite impaired both due to the cystoid macular edema and due to the optic obstruction of the pupil, or due to the inflammatory syndromes.

Surgical Technique for Correction of the IOLs Captures

As these captures are caused by the posterior synechiae, the lens haptics will obviously be strongly stuck under the iris. The destruction of the posterior capsule will not,

MANAGEMENT OF POSTERIOR CHAMBER IOL CAPTURE 419

Fig. 38.11: Preoperation Fig . 38.12: Postoperation

will remain in front of it. This way, the lens-iris chafing is stopped and the symptoms are improved.

The way to accomplish this procedure will depend on the case. We used a lens devised specifically for iridectomy and manufactured by Meridian.

It is a little different from the Abraham lens, because it magnifies the image on the whole surface of the lens, facilitating the use of the YAG laser without the need to rotate it and to find focus position. When it is a very simple capture, a YAG session is enough, using the necessary intensity according to the capsule thickness to create an opening large enough to push the optic part backwards. Then, in the consulting room, a drop of an antibiotic eyedrop and a drop of an anesthetic eyedrop are instilled, and a blepharostat, preferably with the base turned to the nose, is placed to leave the temporal limbus available. Next, a swab is wetted with anesthetic and kept against the temporal limbus for some seconds.

After that, using a syringe with a 30 G 1/2“ needle the limbus is punctured. By placing the needle against the body of the IOL it is pushed back; first a half of the optic zone, and then the other half, if needed. Soon the whole lens will

fit behind the iris and the posterior capsule.

There are cases in which the fibrosis of the posterior capsule is very thick, and destroying it with just a laser session is difficult. In some cases, when using the laser close to the pupillary border, there appear hemorrhages due to vassels not previously noticed in the fibrosis; this hinders visualization and decreases the laser action, forcing to postpone the session.

Cases in which the whole optic zone of the lens is in front of the iris, and the fibrosis of the capsule is very thick, the pupil is usually very small and no matter how large the capsulotomy is, there would still be difficulty moving the lens back. There are cases in which the tensile pressures of the synechiae are so strong that the lens haptic cuts the iris and moves into the anterior chamber, as if fibrous reconstituted the iris; with two or three YAG sessions one can also do an iridotomy in the projection of the haptic, thus creating a space to move it back without the

risk of destabilizing the lens.

In these cases, it would be better to use some Xylocaine 1 percent in the syringe without preservative, slowly mixing it with aqueous humor in order to create enough anesthetic effect to pass the lens through the iris without the patient’s complaint. When the patient does not feel pain, he or she will not even notice the surgical maneuver. As the maneuver is made with a very fine needle, making the paracentesis in bevel and without causing trauma in the incision, practically there is no loss of the aqueous when removing the needle.

With this, the anterior chamber is not lost. In spite of being a simple procedure it can be done in the surgical center by using the surgical microscope. After this procedure we prescribe antibiotic eyedrop in association with more corticoid and a nonhormonal antiinflammatory eyedrop 4 times daily for 20 days, controlling the ocular pressure accordingly.

Complications in the Surgery of the Captures

The complications are rare, what happens with certain frequency are the difficulties. The most common is hemorrhage during the YAG laser. Sometimes we examine a

fibrosis that seems not to have blood vessels, but when we approach the iris bleeding starts. By using the lens we make a pressure on the eye and that usually causes bleeding to stop. However, it hinders the laser treatment, and we have to wait 2 to 3 days for continuation of the treatment.

In some cases the fibrosis is so marked that even using high laser intensity it is not possible to cut it. In these cases if it is possible to use another area that can be used to solve the problem we will use it. On the contrary, we would have to

insist on opening enough with the YAG to fit the optic part of the lens. Another problem is when the capsulotomy is insufficient and when, close to the

inserts of the haptics, there is enough amount of posterior capsule to cause the lens to be impelled forward.

At that moment the lens moves back under pressure, but soon it goes back to the anterior chamber. The capsulotomy would have to be enlarged and the maneuver would have to be repeated.

The other complication possibilities are inherent to the application of the YAG laser, like the ocular hypertension that is usually transient. Retinal detachment, which also has its controversies, could happen. In spite of these difficulties, in almost all of the cases, the patients feel they have received some benefit both in vision and in the visual comfort.

REFERENCES

1.Lindstrom RL, Hermann WK: Pupil capture—prevention and management. Am Intraocul Implant Soc J 9:201-04, 1983.

2.Gimbel HV, Neuhann TH: Development, advantages, and methods of the continuous circular capsulorrhexis technique. J Cataract Refract Surg 16:31-37, 1990.

3.Lavin M, Jagger J: Pathogenesis of pupillary capture after posterior chamber intraocular lens implantation.

Br J Ophthalmol 70:886-89, 1986.

4.Bowman CB, Hansen SO, Olson RJ: Noninvasive repositioning of a posterior chamber intraocular lens following pupillary capture. J Cataract Refract Surg 17:269-80, 1991.

5.Brazitikos PD, Roth A: Iris modifications following extracapsular cataract extraction with posterior chamber lens implantation. J Cataract Refract Surg 17:269-80, 1991.

6.Raposo Fo A, Paiva Fo C, Paiva F: Complicações per e pós operatórias na cirurgia extracapsular e nos implantes intra-oculares. Arq Bras Oftalmol 50:124-29, 1987.

7.Ferraz Fo CPA, Davila BC, Belfort Jr R et al: Lentes intraoculars em uveítes. Arq Bras Oftalmol 50:199-202, 1987.