Like the great white shark, the white cataract can cause catastrophe in the deep. Clinically, the generic white cataract may be divided into four types, which may be differentiated by careful biomicroscopy. The longstanding, mature white lens often has a golden nuclear hue and hard consistency. White cortical cataracts are characterized either by spoking, clefting, corticocapsular adhesions or by diffuse anterior and/or posterior cortical opacification. The swollen intumescent cataract, usually observed in younger patients, shows abundant vacuoles often associated with a white posterior subcapsular opacity. Finally, the liquefied, milky cortex of the Morgagnian cataract may actually permit the nucleus to sink within the capsular bag.
Managing elevated endocapsular pressure and improving intraoperative visualization can turn the surgical course for a white cataract into smooth sailing.ELEVATED ENDOCAPSULAR PRESSURE
Historically, two difficulties that have plagued surgeons when removing white cataracts are unanticipated elevations of the endocapsular pressure that can cause the tear to run peripherally and compromised visualization of the capsulorhexis. Increased endolenticular pressure is most problematic in younger patients with a swollen cortex or in cases of liquefied Morgagnian cataracts. Perhaps the most graphic example of capsular extension secondary to the endolenticular pressure appeared in the video, The Argentinean Flag Sign,1 which depicted a visible white cortex beneath a torn capsule bordered by the blue color of an intact, dye-stained anterior capsule (Figure 1).
Several researchers investigating the issue of increased endocapsular pressure have attempted to puncture the central anterior capsule with a 27-gauge needle in order to aspirate some lens material.2-4 Although this maneuver seemed to lower the endocapsular pressure, the investigators abandoned it, because it could interfere with the capsulorhexis. The technique was more helpful with the Morgagnian cataract, because the surgeon could almost completely aspirate the liquefied cortex and replace it with a more stable viscoelastic agent. A more predictable method for neutralizing endocapsular pressure was using a viscoelastic agent to flatten the lens dome and retard the capsule's tendency to run downhill. Ophthalmologists who had preferred to create the capsulorhexis with a needle often found it easier to control the edge more precisely with a forceps in any of these white cataracts. Still, the successful completion of the capsulorhexis has remained technically difficult for many surgeons.
VISUALIZATIONCapsular Dyes
Compromised visualization is the other challenge surgeons face with all white cataracts. Methods for dealing with this problem include the use of air,5 diathermy,6 high magnification, and oblique illumination.7 The first strategy to work well involves staining the capsule. Reports detail the use of fluorescein,8 autologous blood,9 and indocyanine green (ICG),10 but a real breakthrough occurred when Gerrit Melles, MD, PhD, of Rotterdam, the Netherlands, and his colleagues described the use of trypan blue.11 This dye possesses superior staining characteristics (Figure 2), although several physicians have claimed that it increases capsular fragility, as did Ehud Assia, MD, of Kfar Saba, Israel, in a personal conversation (2001).
US surgeons face a regulatory hurdle with trypan blue. Because the FDA classified the dye as a drug, many US companies consider the cost of bringing it to market to be prohibitive. Whereas ICG may be used off label for an approximate price of $70, trypan blue costs the equivalent of a mere $10 in Europe and less than $5 in South America. Trypan blue would improve surgeons' outcomes in cases of white cataracts,12 and some US surgeons value the dye enough to purchase it internationally.13
Three-Step Surgical Technique
A three-step technique facilitates capsular staining with either ICG or trypan blue while avoiding misdirection of the dye and its accumulation in dense pockets within the viscoelastic material.14 First, the anterior chamber is filled with Healon5 (Pfizer Inc., New York, NY). Gently placing a small amount of BSS (Alcon Laboratories, Inc., Fort Worth, TX) onto the surface of the lens creates a fluid monolayer by elevating the Healon5 into the dome of the chamber. After introducing the capsular dye into the BSS monolayer, we use a specially designed cannula with a posteriorly placed hole (Duckworth and Kent Ltd., Hertfordshire, England) to paint dye onto the anterior capsule. Thus far, in approximately 100 cases, this technique has resulted in consistent, safe, uniform staining of the capsule.
CONCLUSION
We liken the capsulorhexis to the first letter of the alphabet; if A goes awry, then B is bad, C is catastrophic, and D is disastrous. In cases of white cataracts, if the capsulorhexis is unsuccessful, significant complications may follow. The surgeon who neutralizes elevations in endocapsular pressure and who possesses a good technique for staining the capsule can avert a disaster in the deep and instead enjoy a good day of fishing.
James M. Osher, MS, does not hold a financial interest in any products or companies mentioned herein.
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3. Cionni RJ, Buratto L, Osher RH. The White Cataract. Video Journal of Cataract and Refractive Surgery.1992;Vol. 7:Issue 2.
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8. Hoffer KJ, McFarland JE. Intracameral subcapsular fluorescein staining for improved visualization during capsulorhexis in mature cataracts. J Cataract Refract Surgery. 1993;19:566.
9. Cimetta DJ, Gatti M, Lobianco G. Haemocoloration of the anterior capsule in white cataract CCC. Eur J Implant Refract Surg. 1995;7:184-185.
10. Horiguchi M, Miyake K, Ohta I, Ito Y. Staining of the lens capsule for circular continuous capsulorhexis in eyes with white cataract. Arch Ophthalmol. 1998;116:535-537.
11. Melles GR, de Waard PW, Pameyer JH, Hoadijn Beekhuis W. Trypan blue capsule staining to visualize the capsulorhexis in cataract surgery. J Cataract Refract Surg. 1999;25:7-9.
12. Dada T, Ray M, Bhartiya P, Vajpayee RB. Trypan-blue-assisted capsulorhexis for trainee phacoemulsification surgeons. J Cataract Refract Surg. 2002;28:575-576.
13. Osher RH. FDA or DWR? Video Journal of Cataract and Refractive Surgery. 2001;Vol. 17:Issue 4.
14. Osher RH, Marques D, Marques F. A 3-step technique for staining the anterior lens capsule with indocyanine green or trypan blue. J Cataract Refract Surg. In press.
