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Consultation section

Cataract surgical problem: Reply 2

Dick, Burkhard H. MDa

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Journal of Cataract & Refractive Surgery: April 2002 - Volume 28 - Issue 4 - p 578-580
doi: 10.1016/S0886-3350(02)01283-X
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There is an increasing prevalence of pseudoexfoliation syndrome as life expectancy increases. This syndrome is both an ocular and generalized disease, but it is distinct from normal aging.1 A definite clinical diagnosis can be made only in the late stage of manifest pseudoexfoliation and in the stage of mini-pseudoexfoliation showing early rub-off of the material from the anterior lens capsule, typically and characteristically in the upper nasal quadrant. Additional subtle clinical signs include loss of melanin from the peripupillary pigment epithelium of the iris (producing transillumination defects in the sphincter area), anterior chamber melanin dispersion after pupil dilation, melanin deposition on anterior segment structures (particularly the trabecular meshwork), and insufficient mydriasis. The existence of circular or segmental posterior synechias without any other obvious cause or in cases of asymmetric findings should alert one to suspect pseudoexfoliation syndrome.

The presence of pseudoexfoliation presents unusual challenges, and special care should be exercised before, during, and after surgery.2 There is a higher risk of intraoperative complications in eyes with pseudoexfoliation, especially with an anterior chamber depth less than 2.5 mm.3 Preoperative zonule weakness seems to lead to anterior movement of the lens.

There are several considerations when selecting a surgical technique for patients with pseudoexfoliation.

Glaucoma

In pseudoexfoliation eyes with glaucoma that do not need filtration surgery at the time of cataract surgery, a temporal clear corneal incision is preferred because it will not hinder future filtration surgery in a superior location.4 The primary cause of intraocular pressure (IOP) elevation in pseudoexfoliation glaucoma is obstruction of the intertrabecular spaces by exfoliative material. In cases of increased IOP, trabecular aspiration is performed with a suction force of 150 mm Hg under light tissue-instrument contact using a modified intraocular aspiration probe (Geuder). Bimanual trabecular aspiration is safe and efficacious in decreasing IOP in cases of pseudoexfoliation.5 However, there is a slight regression in effect after about 3 years that is attributed to undisturbed liberation of exfoliative debris.

Small Pupil

Highly viscous ophthalmic viscosurgical devices (OVDs) such as sodium hyaluronate 2.3% (Healon5®) are suitable to widen a small pupil and simplify capsulorhexis.6 Care should be taken not to overexpand the anterior chamber with the OVD as this might challenge the zonular integrity in eyes with pseudoexfoliation. The Beehler pupil dilator helps stretch the pupil while creating tiny microsphincterotomies circumferentially. Pupils enlarged to about 6.0 mm in this manner maintain a good cosmetic appearance. The small pupil can also adequately be managed by iris hooks, iris rings, and pupil stretching with 2 hooks.

Capsulorhexis

Traction on the capsule can unzip weakened zonules. Centripetal traction on the capsular flap damages the adjacent weakened zonules, especially in areas of missing zonules. In eyes with loose zonules, 2-handed capsulotomy using tangential forces as described by Neuhann7 is a preferred adjunctive technique. After the capsulotomy is started, the capsular flap is stabilized with the a forceps through the main incision while a second instrument, such as a bifurcated spatula, is introduced through the paracenteses. Slight backward traction is placed on the flap with the forceps while the second instrument advances the torn edge in a tangential manner.

Eyes with pseudoexfoliation are susceptible to marked shrinkage of the capsulorhexis because the forces of fibrosis and contraction are unopposed by zonular traction. The capsulorhexis size is extremely important in eyes with pseudoexfoliation; it should be at least 5.7 mm to leave a smaller amount of lens epithelial cells (LECs). Bimanual aspiration and polishing of the backside of the anterior capsule to the equator using a Menapace aspiration probe (Geuder) will effectively decrease the number of LECs and further decrease the incidence of symptomatic capsule contraction.

Hydrodissection and Hydrodelineation

Cortical cleaving hydrodissection is performed very gently in multiple locations with gentle central lens decompression, especially when one decompresses the bag after having performed the posterior fluid wave.8 This should alleviate the chances of depressing the lens with excessive forces. Hydrodelineation is very useful and produces an epinuclear shell as an added safeguard. Depression of the posterior incision lip with the cannula ensures easy OVD or fluid egress from the eye.

Phacoemulsification

With 2-handed lens manipulation, the forces can be truly tangential and divided by using opposite sides of the same meridian.

High cavitation tips obliterate nuclear material in advance of the tip without exerting forces on the lens zonules and facilitate grooving. Some tip configurations (eg, Kelman) allow variation of the phaco-sweep procedure by a lateral and rotational motion of the phaco probe (Neosonix, Alcon). The nucleus is stabilized with a second instrument during grooving. Downslope sculpting avoids nudging the nucleus in the sculpting direction to reduce unnecessary traction to the zonules in the subincisional area. In addition, the nucleus is pushed toward the phaco tip to maximize the efficiency of the tip while elevating the lens slightly.

Chopping and nonrotational cracking techniques are least traumatic for dismantling the nucleus. The epinuclear shell helps stabilize the nucleus.4

Cortical Aspiration

Cortical aspiration is a threat to the zonules in eyes with pseudoexfoliation. In addition to hydrodissection, viscodissection may assist in cortex removal.9 Aspiration of residual cortex and capsule polishing is safer after IOL and CTR implantation because these devices stabilize the capsular bag. Implantation of a foldable hydrophobic monofocal IOL with PMMA haptics sized for bag placement (overall diameter 12.5 mm) is preferred. A minimal IOL optic diameter of 6.0 mm allows an extra margin of safety should the lens decenter. Instead of stripping the cortex centrally, tangential traction with the irrigation/aspiration (I/A) tip is recommended because stripping away from areas of zonular dehiscence localizes forces on weakened zonules, which might lead to further unzipping of the zonules.

Capsular Rings

The CTR prevents concentration of forces on individual zonules by distributing all forces applied to the entire zonular apparatus. It keeps the bag stretched throughout the procedure, allowing for greater safety. Unfortunately, the pressure of the ring against capsular fornices bolsters zonular traction on the capsule in some cases. Moreover, the CTR does not counter the force of constriction after metaplasia and fibrosis, nor does it prevent capsular bag shrinkage. Therefore, in cases with no or little zonular dehiscence, a capsular bending ring (CBR) is routinely implanted in eyes with pseudoexfoliation. The CBR effectively counteracts capsular bag shrinkage and leads to a statistically significant reduction in PCO.10 Both the CTR and CBR cause fewer intraoperative and postoperative complications by stabilizing the capsule. In cases of greater intraoperative zonular dehiscence, the Cionni ring provides additional safety.

Improvements in phacoemulsification technology and technique and new capsular supporting rings enable cataract surgery in eyes with pseudoexfoliation with fewer complications.

Because there are several options that would be safe if a combined procedure (pars plana vitrectomy with secondary IOL implantation) is performed in the future in cases of the relatively rare late dislocation of the capsular bag/IOL complex, there is no need to change the ideal location for IOL implantation (capsular bag) or surgical technique to anterior chamber or sulcus implantation, especially in a young, healthy individual with pseudoexfoliation. So far, we are not aware of definite clinical consequences of the systemic occurrence of pseudoexfoliative material. Some intriguing observations, such as a higher incidence of abdominal aneurysms of the aorta in patients with pseudoexfoliation,1 need further detailed interdisciplinary investigations and may influence the role of the ophthalmologist.

References

1. Naumann GOH, Schlötzer-Schrehardt U, Küchle M. Pseudoexfoliation syndrome for the comprehensive ophthalmologist. Ophthalmology 1998; 105:951-968
2. Jehan FS, Mamalis N, Crandall AS. Spontaneous late dislocation of intraocular lens within the capsular bag in pseudoexfoliation patients. Ophthalmology 2001; 108:1727-1731
3. Küchle M, Viestenz A, Martus P, et al. Anterior chamber depth and complications during cataract surgery in eyes with pseudoexfoliation syndrome. Am J Ophthalmol 2000; 129:281-285
4. Fine IH, Hoffman RS. Phacoemulsification in the presence of pseudoexfoliation: challenges and options. J Cataract Refract Surg 1997; 23:160-165
5. Jacobi PC, Dietlein TS, Krieglstein GK. Bimanual trabecular aspiration in pseudoexfoliation glaucoma: an alternative in nonfiltering glaucoma surgery. Ophthalmology 1998; 105:886-894
6. Dick HB, Krummenauer F, Augustin AJ, et al. Healon5 viscoadaptive formulation: comparison to Healon and Healon GV. J Cataract Refract Surg 2001; 27:320-326
7. Neuhann TF. Capsulorhexis. In: Steinert RF, ed, Cataract Surgery: Technique, Complications, & Management. Philadelphia, PA, WB Saunders Co, 1995; 134-142
8. Fine IH. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508-512
9. Dick HB, Schwenn O. Viscoelastics in Ophthalmic Surgery. Berlin, Heidelberg, New York, NY, Springer, 2000; 58
10. Nishi O, Nishi K, Menapace R, Akura J. Capsular bending ring to prevent posterior capsule opacification: 2 year follow-up. J Cataract Refract Surg 2001; 27:1359-1365
© 2002 by Lippincott Williams & Wilkins, Inc.