achieved with a given microkeratome is mandatory so

a surgeon will be able to predetermine that if a thicker-than-

expected flap is created, sufficient residual tissue would remain

and if that is not the case, the surgeon might consider

undercorrecting the eye, decreasing the ablation diameter,

performing photorefractive keratectomy, or implanting a phakic

intraocular lens.dPerry S. Binder, MD

Capsule staining techniques

Marques and coauthors1 described their 3-step

technique for staining the anterior capsule with

indocyanine green or trypan blue. They also discussed

other techniques that have been and are used including

injecting the dye under an air bubble and injecting the

dye into an anterior chamber filled with an ophthalmic

viscosurgical device (OVD).

There is another, arguably easier technique for cap-

sule staining that the authors did not mention. After

the section is made, trypan blue is injected directly

into the anterior chamber, essentially replacing aque-

ous. After 60 seconds, the trypan blue is washed out

with a balanced salt solution and the degree of capsule

staining is assessed. If staining is sufficient, the opera-

tion is continued in the usual manner. If staining is

insufficient, the process is repeated.

This technique avoids the problems with air

bubbles and OVDs in determining the correct plane

and also avoids problems with differential or partial

staining. The only concern is whether the direct

exposure to the endothelium is more damaging than

the techniques discussed by Marques and coauthors.

However, we know that trypan blue has been used for

many years to evaluate corneal endothelial cells before

keratoplasty with very little or no toxicity documented,

at least not in the concentrations that we use clinically

for capsule staining.2,3 In addition, we and many of our

colleagues have been using this simple technique for

the past 4 years with no detrimental effects. Admit-

tedly, we can only advocate this technique for trypan

blue as we have no experience with indocyanine green.

ALI A. MEARZA, MRCOPHTH

AVINASH A. KULKARNI, MRCOPHTH

Kingston-upon-Thames, United Kingdom

References1. Marques DM, Marques FF, Osher RH. Three-step tech-

nique for staining the anterior lens capsule with indocya-

nine green or trypan blue. J Cataract Refract Surg 2004;30:13–16

2. Georgiadis N, Kardasopoulos A, Bufidis T. The evalua-tion of corneal graft tissue by the use of trypan blue. Oph-thalmologica 1999; 213:8–11

3. Singh G, BohnkeM, von-Domarus D, et al. Vital stainingof corneal endothelium. Cornea 1985-86; 4:80–91

Reply: Mearza and Kulkarni are correct in their comments.

Along with the techniques mentioned in our paper, it is possible

to stain the anterior capsule by replacing the aqueous humor

with trypan blue. However, this technique must be considered

cautiously because of possible drawbacks. First, the entire

anterior segment will be stained unnecessarily since only the

anterior capsule needs to be stained. Second, the anterior

chamber may be overfilled inadvertently, stressing the zonules

and leading to migration of dye to the anterior vitreous, with loss

of red reflex compromising the subsequent steps of the

procedure (phacoemulsification, cortex aspiration, and intraoc-

ular lens implantation). Finally, the endothelial cells will be

exposed to the dye, which is more damaging than exposure to

an OVD, especially in eyes with a low cell count, although it

may not be clinically significant in healthy corneas.dFrederico

F. Marques, MD, Daniela M.V. Marques, MD

LETTERS

2462 J CATARACT REFRACT SURG

Trypan blue staining of anteriorlyplaced zonules in patientswith pigment dispersion

The article by Kelty and coauthors1 highlights the

seldom-considered finding of anteriorly placed

zonules. The authors noted staining of the zonules after

application of indocyanine green (ICG) dye used to

enhance visualization of the anterior capsule. This is of

particular relevance in patients having phacoemulsifi-

cation surgery because of the need for an intact con-

tinuous curvilinear caspsulorhexis to enable stable

in-the-bag fixation of the intraocular lens.2

We have observed anteriorly placed zonules made

visible following the use of trypan blue dye 0.1%

(Vision Blue, Dorc International) to stain the anterior

capsule during cataract surgery in 2 patients with signs

of pigment dispersion. Moroi et al.3 recently described

a series of 15 patients with anteriorly placed zonules

associated with signs of anterior segment pigment

dispersion. They speculate that contact between the

zonules and iris pigment epithelium at the pupillary

ruff and central iris was the cause of pigment release.

—VOL 30, DECEMBER 2004

zonular free zone. Such a small capsular opening may increase

the possibility of intraoperative damage to the capsulorhexis,

difficulty of lens removal, and a postoperative risk for cap-

sulorhexis contraction or phimosis. It remains unclear whether

eyes with anteriorly placed zonules have a redistribution

of the usual number of zonules or an augmented supply,

some of which are anteriorly located. Accordingly, it is difficult

to determine whether removal of some zonules during the

capsulorhexis process would affect structural support. Rather

than a very small capsulotomy, we restate our recommendation

to perform a spiral capsulorhexis, starting small and enlarging

centripedally so an errant tear can be rapidly rescued if a

peripheral extension begins.

Chen and coauthors also suggest ‘‘.a capsular tension

ring [CTR] may reduce the potential for peripheral extension of

the capsulorhexis and zonular dialysis.’’ This implies placement

of a CTR before capsulorhexis completion. This maneuver

may carry potential hazards as ring placement through an

incomplete tear can cause an extension during ring placement

that might not otherwise occur. Capsular tension rings have

been a wonderful advance in the treatment of existing zonular

dialysis or instability; yet, it is unclear whether standard,

nonfixatable CTRs have an advantage in the prophylaxis of

future zonular dialysis, unlike the modified fixatable (Cionni)

CTRs. If there is concern about zonular countertraction for late

capsulorhexis or phimosis (especially in a small capsulorhexis),

CTR placement may have prophylactic benefits.dMichael E.

Snyder, MD

Postoperative endophthalmitis

In their article on postoperative endophthalmitis,1

Sandvig and Dannevig comment that the corner-

stone of management, as with any infection, includes

identification of the responsible organisms. In their

study, the overall frequency of positive cultures was

LETTERS

Although often subtle, long, anteriorly inserted

zonules may be visible on slitlamp biomicroscopy and

are easily missed. We suspect these zonules may be

more common than thought. Anteriorly inserted

zonules should be specifically looked for during pre-

operative assessment of patients with cataract, partic-

ularly patients with signs of pigment dispersion in the

form of corneal endothelial pigment deposits, iris trans-

illumination defects, and increasedtrabecular meshwork

pigmentation.

When anteriorly inserted zonules are noted, con-

sideration should be given to improving preoperative

visualization of the zonules with the use of trypan blue

or ICG staining. The creation of a small capsulorhexis

to minimize tearing of the zonular insertions and

placement of a capsular tension ring may reduce the

potential for peripheral extension of the capsulorhexis

and zonular dialysis.

SIMON D.M. CHEN, FRCOPHTH

NICHOLAS GLOVER, FRCOPHTH

C.K. PATEL, FRCOPHTH

Oxford, United Kingdom

References1. Kelty PJ, Snyder ME, Schneider S. Indocyanine green

staining of anteriorly placed zonules. J Cataract RefractSurg 2003; 29:2229–2231

2. Gimbel HV, Neuhann T. Development, advantages, andmethods of the continuous circular capsulorhexis tech-nique. J Cataract Refract Surg 1990; 16:31–37

3. Moroi SE, Lark KK, Sieving PA, et al. Long anteriorzonules and pigment dispersion. Am J Ophthalmol2003; 136:1176–1178

Reply: The letter by Chen and coauthors adds to our

reported case of ICG staining of anteriorly placed zonules. In

their case, they stained anteriorly placed zonules with trypan

blue. They also comment on the subsequently published article

by Moroi and coauthors, which describes a series 15 patients

(29 eyes) with anteriorly placed zonules. While the letter

reaffirms the important point that ICG or trypan blue vital

staining can assist in capsulorhexis, some of the comments

may be confusing.

As demonstrated in our case and in 13 of 19 eyes

reported by Moroi and coauthors in which measurements of

the zonular free zone were taken, this central area measures

less than 3.0 mm in diameter. The zone is even smaller when

corneal magnification is taken into account. To reduce the

chance of a peripheral extension during capsulorhexis creation,

Chen and coauthors recommend a capsulorhexis within the

75%. They labeled these cases as true endophthalmitis

and observed the bacterial growth was associated with

a poor final visual acuity. In the early postoperative

period, the differential diagnosis between infectious

and noninfectious inflammatory reaction has to be

made on clinical signs and symptoms only.2 If in

doubt, the eye should be treated as if it were infected

and an anterior chamber and vitreous tap should be

performed.

It has been our observation that the presence of

thick fibrinous exudates extending from the wound

(main incision or the side-port stab) into the anterior

chamber and joining those in the center over the

intraocular lens and pupil, taking the shape of a chem-

istry ‘‘retort,’’ strongly indicates an infective cause

2463J CATARACT REFRACT SURG—VOL 30, DECEMBER 2004