Staining the anterior capsule with indocyanine green or trypan bluefor capsulorhexis in eyes with white cataract

Yang Xiao1,2, Yu-hong Wang1,2, Zhi-yong Fu1 & Hui Hong11Department of Ophthalmology, Beijing Friendship Hospital, Affiliate of Capital University of MedicalSciences, Road Yong-an 95, Xuanwu District, Beijing, 100050, People’s Republic of China ; 2Departmentof Ophthalmology, Beijing Chao Yang Hospital (West Campus), Affiliate of Capital University of MedicalSciences, Road Jing-yuan 5, Shijingshan District, Beijing, 100043, People’s Republic of China

Received 3 November 2004; accepted 4 August 2005

Key words: cataract, indocyanine green, trypan blue, phacoemulsification, intraocular lens

Abstract

Aim: To assess the efficacy and safety of indocyanine green (ICG) 0.5% and trypan blue 0.1% for anteriorcapsule staining in cases of white cataract. Methods: This prospective study comprised 55 eyes of 55patients with white cataract that had phacoemulsification with foldable intraocular lens implantation. ICGin 30 eyes and trypan blue in 25 eyes were used under air to stain the anterior lens capsule. The stainingpatterns and the ease of creating a continuous curvilinear capsulorhexis (CCC) were assessed; the intra-operative and postoperative complications were noted. The mean follow-up was 17.68±1.65 months.Result: Either ICG or trypan blue stained the anterior capsule uniformly. However, the staining providedby trypan blue was slightly superior. A CCC was successfully achieved in 25 eyes (100%) with trypan blue,and 29 eyes (96.7%) with ICG, respectively. There was no significant postoperative reaction in any eye.Conclusion: The use of vital dyes such as ICG and trypan blue guarantees a complete CCC and makes itpossible to deliver the benefits of phacoemulsification in the patients with white cataract.

Introduction

There are 4.5 million blind people in China. Cat-aract accounts for 41% of all blindness in thecountry. White cataracts constitute a significantproportion of cataracts [1]. Creating the continu-ous curvilinear capsulorhexis (CCC) and emulsi-fying the hard nucleus make phacoemulsificationchallenging in eyes with white cataract. Thesebottlenecks must be coped with. Hence, this pro-spective study assessed the feasibility, risks, andpostoperative outcomes of phacoemulsification insuch cases with the use of indocyanine green (ICG)or trypan blue as an adjunct for performing CCCin the absence of a red reflex.

Materials and methods

This study included 55 eyes of 55 patients, whohad phacoemulsification with posterior chamber

intraocular lens (PC IOL) implantation at BeijingFriendship Hospital between October 2000 andAugust 2002. The mean age of the 23 men (41.8%)and 32 women (58.2%) was 68.2±5.4 years (range58–86 years). Inclusion criteria were the presenceof white mature or hypermature cataract and well-reacting pupil with accurate projection of rays inall quadrants. Patients with ocular disease otherthan cataract were excluded.

Patients were randomly assigned to 1 of 2groups based on the type of anterior capsule stain.There were 30 patients in the ICG group and 25patients in the trypan blue group. The mean age ofthe patients was 67.3±4.8 years in the ICG group,69.2±5.6 years in the trypan blue group.

The preoperative best corrected visual acuity(BCVA) in all patients ranged from counting fin-gers close to the face to light perception; 45patients (81.8%) had an acuity of hand move-ments or worse.

International Ophthalmology (2004) 25: 273–276 � Springer 2006DOI 10.1007/s10792-005-2228-4

The ICG solution was prepared by dissolving25 mg of ICG in 0.5 mL of an aqueous solvent,which was mixed in 4.5 mL of fortified balancedsalt solution (BSS Plus�). Trypan blue 0.1% wasobtained as a premixed, sterile, ready-to-usesolution (Vision Blue�, DORC International,Netherlands).

After a side-port incision was made, a superior3.2 mm clear corneal incision or scleral tunnelincision (the first two eyes in each group) wascreated with metal knives. Anterior capsule stain-ing with ICG or trypan blue was done under air.After 10 seconds, the anterior chamber was thor-oughly washed with BSS. Sodium hyaluronate 1%was injected into the anterior chamber. A CCCwas initiated by preparing a small, triangular,central, anterior capsular flap with a bent 26-gaugedisposable needle. The CCC was completed usinga cystotome when possible; a Utrata capsulorhexisforceps was used in cases in which the loose cor-tical matter did not give adequate intralenticularsupport. Phacoemulsification was performed witha divide-and-conquer nucleofractis techniqueusing a peristaltic pump machine (Megatron�,Geuder) and flare tip. Automated irrigation/aspi-ration (I/A) of the cortical material was done. Ahydrophobic, foldable, acrylic IOL (AcrySof�,Alcon Laboratories) was implanted. All patientswere prescribed a standard regimen of a topicalsteroid and antibiotic postoperatively.

Results

Either ICG or trypan blue stained the anteriorcapsule uniformly. Comparing the 2 dyes used, thestaining provided by trypan blue was slightlysuperior. The side ports were stained with ICG ortrypan blue in all of the cases. Postoperatively, theside-port staining was very faint at 1 day andcompletely gone at 2 days.

A CCC is performed easily by the enhancedcontrast of the capsule in blue or green. A CCCwas successfully achieved in 25 eyes (100%) withtrypan blue, and 29 eyes (96.7%) with ICG. Thesuccess rates in creating a complete CCC were notsignificantly different between the two groups (chisquare=0.01, p=0.9229). Both of ICG and trypanblue could also reveal areas of anterior capsulefibrosis and delineate their boundaries. Anteriorcapsule fibrosis was found in 2 eyes with ICG and

3 eyes with trypan blue. The direction of thetearing edge of the capsulorhexis was fashioned toencompass the fibrotic part of the anterior capsule.In 1 eye with anterior capsule fibrosis unmaskedby ICG, an attempt was failed to circumvent thearea by changing the direction of the CCC, and theCCC was incomplete eventually.

In a 74-year-old woman in the ICG group, agreen glow was observed immediately after phac-oemulsification. The ICG had stained not only theanterior capsule but also the anterior vitreous andthe posterior surface of the posterior capsule. Apreviously compromised zonular apparatuswithout detectable zonular dialysis was highlysuspected. On the first postoperative day, thepatient presented with ‘‘dark and green’’ vision,which lasted nearly 1 week.

Emulsification of the nucleus was accomplishedin all eyes, The equivalent phaco time was54.5±22.3 seconds and 52.6±19.5 seconds in theICG and trypan blue groups, respectively. Thedifference between groups was not significant(t=0.333, p=0.7405). There was no significantpostoperative reaction in any eye. One day post-operatively, corneal edema was present in 11 eyes(36.7%) in the ICG group and 8 eyes (32.0%) inthe trypan blue group. The difference betweengroups was not significant (chi square=0.006,p=0.9394). All cases of edema resolved within7 days. At the last follow-up, all of the generalaspect of the eyes were unremarkable at slitlampexamination, and the corneas were clear and pre-sented with normal thickness. The mean follow-upwas 17.68±1.65 months (range 14.5–20 months).One week after surgery, all patients had a BCVAof 20/30 or better and the acuity remained at thatlevel at 1 month.

Discussion

White cataracts pose a formidable challenge tosurgeons performing phacoemulsification. There-fore, systematic preoperative evaluation and cate-gorization of white cataracts based on theintralenticular pressure, status of the cortex andnuclear colour to permit proper surgical planningand successful management of such cases withphacoemulsification was highly recommended.

Creation of a CCC is a critical step in small-incision phacoemulsification cataract extraction.

274

In eyes with white cataract, the transparent ante-rior capsule is difficult to visualize. The cataractexudes milky cortex through the capsulotomy,interfering with the visualization of the leadingedge of the CCC, The accepted recommendationsto aid CCC in such cases are dimming theoperating room lights, increasing the operatingmicroscope’s magnification and coaxial illumina-tion, and using high-density viscoelastics agents.The use of air, diathermy, an endoilluminator, avitrectome, scissors, and the 2-stage CCCapproach have also been suggested [2]. However,all the measures mentioned above could notdirectly enhance visualization of the anteriorcapsule during capsulorhexis and guarantee acomplete capsulorhexis.

Staining the anterior capsule with a biocom-patible dye was a milestone in the management ofwhite cataract with phacoemulsification. Trypanblue, ICG, gentian violet, fluorescein, and methy-lene blue have been used in human eyes. Stainingthe capsule with a combination of gentian violet0.1% and methylene blue 1% became obsoletebecause of the endothelial toxicity [2].

No midterm endothelial cell damage wasinduced by the intraoperative use of trypan bluefor staining the anterior lens capsule, according toVan Dooren et al. [3]. Holley [4] demonstrated that3-minute exposure to 0.5% ICG had no adverseeffect on corneal endothelial function, ultrastruc-ture, or viability. The study provides a safetyprofile for the corneal endothelium when ICG isused as an intraocular tissue stain in ophthalmicsurgery. Horiguchi also demonstrated that stain-ing the anterior capsule using a 2% solution ofICG in patients with mature cataract was safethrough specular microscopy endothelial cellcount and laser flare–cell photometry.

Because ICG and trypan blue selectively staindead corneal endothelial cells, these 2 dyes nei-ther stain alive corneal endothelial cells norobstruct the surgeon’s view. Because of its lowermolecular weight (376 Da), fluorescein sodiumcan stain the cornea and migrate to the vitreouscavity. Thus both ICG (775 Da) and trypan blue(960.8 Da) are currently preferred over fluores-cein, due to better staining of the anterior capsuleand absence of vitreous leakage (due to highmolecular weight).

The complications associated with capsulardyes are few. Werner [5] reported two cases of

permanent blue discoloration of a hydrophilicacrylic IOL after intraoperative use of trypan bluedye. It is recommended that the surgeon should becareful when using any capsular dyes in cataractsurgery combined with implantation of hydro-philic acrylic lenses having a high water content.Chowdhury et al. [6] reported a case of inadvertentstaining of the vitreous with trypan blue, andexplained that a compromised zonular apparatuswithout detectable zonular dialysis secondary toprevious trauma could be responsible for theproblem. However, no histological abnormalitiesin any of the anterior chamber angle specimensand no signs of toxicity were found after the pro-longed presence of trypan blue at a concentrationof 0.6 mg/ml in the vitreous cavity of rabbit eyes[7]. And the use of ICG and trypan blue to stainthe retinal internal limiting membranes andepiretinal membranes in the vitreoretinal surgerywas also described. Thus, the remnant of trypanblue and ICG in the vitreous cavity may not be asignificant concern.

Several methods of staining the anteriorcapsule have emerged. Staining under an air bub-ble is currently used by most surgeons, althoughpitfalls of this technique are usually described asfollows: a less stable anterior chamber, a progres-sive dilution of the dye, air bubble damaging thecorneal endothelium. The drawbacks of this classictechnique may not be great concern throughseveral adjustments. Additionally, in developingcountries like China, where white cataracts are acommon entity, economic constraints may makeinjection under an air bubble a more viable optionthan the viscoelastic-dye combination.

In terms of white cataract, another choke is thepresence of a hard and brown nucleus. The divide-and-conquer and phaco-chop techniques are equ-ally effective in nuclear management. In whitecataract, the chopper may traumatize the posteriorcapsule using the phaco-chop technique, as it isnot protected by an epinuclear cushion. Thus thefirst technique was deemed to be reasonable byboth of us. Furthermore, the bevel-down tech-nique and flare tip were preferred for phacoemul-sification in eyes with white cataract.

We believe that the use of vital dyes such asICG and trypan blue guarantees a complete CCCand makes it possible to deliver the benefits ofphacoemulsification in the patients with whitecataract.

275

References

1. Mao WS, Hu TS. An epidemiologic survey of senile cataractin China. Chin Med J 1982; 95(11): 813–818.

2. Jacob S, Agarwal A, Agarwal A, Agarwal S, Chowdhary S,Chowdhary R, Bagmar AA. Trypan blue as an adjunct forsafe phacoemulsifcation in eyes with white cataract. JCataract Refract Surg 2002; 28(10): 1819–1825.

3. Van Dooren BT, de Waard PW, Poort-van Nouhuys H,Beekhuis WH, Melles GR. Corneal endothelial cell densityafter trypan blue capsule staining in cataract surgery [letter].J Cataract Refract Surg 2002; 28(4): 574–575.

4. Holley GP, Alam A, Kiri A, Edelhauser HF. Effect ofindocyanine green intraocular stain on human andrabbit corneal endothelial structure and viability. Anin vitro study. J Cataract Refract Surg 2002; 28(6):1027–1033.

5. Werner L, Apple DJ, Crema AS, Izak AM, Pandey Sk,Trivedi RH, et al. Permanent blue discoloration of ahydrogel intraocular lens caused by intraoperative trypanblue. J Cataract Refract Surg 2002; 28(7): 1279–1286.

6. Chowdhury PK, Raj SM, Vasavada AR. Inadvertent stain-ing of the vitreous with trypan blue. J Cataract Refract Surg2004; 30(1): 274–276.

7. Veckeneer M, van Overdam K, Monzer J, Kobuch K, vanMarle W, Spekreijse H, et al. Ocular toxicity study of trypanblue injected into the vitreous cavity of rabbit eyes. Graefe’sArch Clin Exp Ophthalmol 2001; 239(9): 698–704.

Address for correspondence: Yang Xiao, Department of Oph-

thalmology, Beijing Friendship Hospital, Affiliate of Capital

University of Medical Sciences, Road Yong-an 95, Xuanwu

District, Beijing 100050, People’s Republic of China

E-mail: xiaoyangmd@yahoo.com.cn

276