another potential flaw in wound construction and closure. The clear corneal tongue may be associated with postoperative wound leak even when a suture is used to reinforce wound closure (44).

Other studies suggested that there is no increased risk of POE with sutureless clear corneal incisions. In a retrospective study of POE from 2000 to 2004, Miller et al. found a relatively low overall rate of POE and no statistically significant risk from clear corneal incisions (3). In another large retrospective report from the United Kingdom, no significant increase in the rate of POE was identified from 1996 to 2004, a period when there was a transition from scleral tunnel to clear corneal incisions (4). As mentioned previously, Ng et al. found no relationship between wound type and POE (6). The largest study looking at the endophthalmitis risk of clear corneal incisions was conducted as part of the National Cataract Registry in Sweden (25). In that prospective study of 225,471 cataract surgeries, there was a slightly higher rate of POE in eyes with clear corneal incisions (0.053%) compared to scleral incisions (0.036%), but that difference did not reach statistical significance (p = 0.14). Notably, 99% of the patients in that study received an intracameral cefuroxime injection, while less than 5% received postoperative topical antibiotics (25).

One rationale cited for using micro-coaxial or microbiaxial phacoemulsification is the possibility that smaller incisions might reduce the risk of POE. As with prophylactic antibiotics, the low incidence of infection makes it very difficult to prove the superiority of one incision size over the other in a prospective study. Furthermore, improperly constructed incisions or those that are stretched by instrumentation can always leak, regardless of their width. Nonetheless, a smaller incision should be more watertight if all other variables are the same. Finally, there is a general agreement that a suture should be placed if the incision is not watertight at the conclusion of surgery (45).

6.10.3 Summary

Because of the low incidence of POE, it is difficult to conduct clinical trials of sufficient size to prove or compare the efficacy of different preventive measures. Overall, evidence-based literature supports the notion that delivering a large intracameral level of antibiotic immediately postoperatively is beneficial in preventing

infection. The majority of clinical evidence suggests that this can be achieved very effectively using an intracameral injection of antibiotic at the end of the case. Other methods, such as subconjunctival injection or topical administration, may also be able to achieve a high level of intracameral antibiotic. Although there is less clinical evidence demonstrating efficacy, the experimental rationale, ease of use, commercial availability, and track record of safety likely underpin the widespread use of topical antibiotics in some countries.

Incision integrity is another important factor in the rate of POE. Poor wound construction, regardless of the size, type, and location, undoubtedly increases the risk. Because of their shorter radial length, clear corneal incisions are likely to be less forgiving for faulty wound architecture or distortion by instrumentation. Regardless of its size and location, one must be prepared to suture the incision if it is not sufficiently watertight.

Take Home Pearls

ßRetrospective, clinical studies suggest that subconjunctival antibiotics may be protective

against endophthalmitis.

ßAlthough the ideal antibiotic choice for endophthalmitis prevention is not known, fluo-

roquinolones are the commonly used topical agents, while cefuroxime and vancomycin are the most common intracameral choices.

ßThere is no consensus on the ideal mode of antibiotic administration, but there is signifi-

cant clinical evidence supporting the direct intracameral injection of antibiotic.

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ßThe advantages of biaxial microincision phacoemulsification have been elaborated in a

variety of papers in the literature [2–10]. This technique is believed to have distinct fluidic advantages.

ßThe separation of inflow from aspiration and phaco allows the fluid to come in through one

side of the eye and exit through the opposite side.

ßCompeting currents are absent at the phaco tip.

ßIt is easier to achieve a nearly closed system.

ßCases that are extremely challenging or even impossible with coaxial phaco are easily

accomplished by biaxial microincision phaco.

7.1 High Myopia

In highly myopic eyes, a situation in which the anterior chamber is maintained in a completely stable configuration without trampolining the vitreous face can be achieved by keeping the irrigating handpiece in the eye throughout the case. Chopping takes place in the usual manner. With the completion of chopping and mobilization of the segments and the epinucleus,the irrigating chopper should be kept in the eye and the phaco needle should be removed. Then after removing the residual cortex, the viscoelastic Viscoat® (Alcon Laboratories, Fort Worth, Texas) should be infused for the implantation of the intraocular lens (IOL), without

1This chapter is an update of the previously published Fine et al. [1]. Reprinted with permission from Jaypee Brothers, New Delhi, India

I. H. Fine

Oregon Health & Science University, Drs. Fine, Hoffman and Packer, 1550 Oak Street, Suite 5, Eugene, OR 97401, USA e-mail: hfine@finemd.com

shallowing the anterior chamber. It is believed that eventually there may be a documented decreased incidence of retinal detachment in high myopia as a result of nontrampolining of the vitreous face during phaco, and the implantation of IOLs that fill the capsule, such as dual-optic IOLs or IOLs that arch posteriorly, as does the Crystalens.

7.2 Posterior Polar Cataract (Fig. 7.1)

In cases of posterior polar cataracts, 35% have defective posterior capsules [11, 12] and almost all have weakened capsules, and so, it is very important not to overpressurize the eye and perhaps, force nuclear material through the defective posterior capsule. By the same token, it is important not to shallow the chamber and have the nucleus come forward, and possibly open the defect in the posterior capsule. These cases are advantageously done with biaxial microincision phacoemulsification, because of the anterior chamber stability [13].

Hydrodelineation is done,without hydrodissection, and then the endonucleus is carefully chopped into