Is Endophthalmitis on the Rise?

Of the numerous advances in the field of cataract surgery during the last half of the 20th century, the introduction of sutureless phacoemulsification using clear corneal incisions has affected the field most significantly. With its efficient technique, minimal rate of surgically induced trauma, shortened operative times, low induction of astigmatism, limited postoperative inflammatory response, and fast postoperative recovery, sutureless, clear corneal cataract extraction has steady gained acceptance among cataract surgeons since its introduction in 1992.1 In the most recent survey of ASCRS members, Leaming et al2 reported that the clear corneal incision and the sutureless techniques are preferred by 72% and 92% of US surgeons, respectively.

During the last decade, however, reports have indicated that the incidence of endophthalmitis after cataract surgery may be on the rise, and some have speculated about whether the complication is associated with clear corneal incisions.3,4 Although the greater rate of infection may primarily be due to increased antibacterial resistance, the absence of a reported increase in endophthalmitis following other intraocular surgeries (penetrating keratoplasty, trabeculectomy, etc.) during this period and the proliferation of aseptic surgical techniques challenge this argument. Other factors therefore must be carefully investigated, and the sutureless clear corneal incision technique remains a possible candidate.

Literature Review and Laboratory Investigation

In 2000, Colleaux and Hamilton3 reported a two-and-a-half times greater incidence of endophthalmitis following cataract extraction with a sutureless, clear corneal incision relative to a scleral tunnel incision. More recently, Nagaki et al4 reported an almost sixfold greater risk in endophthalmitis associated with clear corneal incisions compared with sclerocorneal incisions. A recent review of the English-language literature presented at the 2003 AAO annual meeting analyzed more than 200 studies (comprising over 3 million cataract surgeries) that addressed endophthalmitis after cataract extraction between 1963 and 2003.5 When the study period was split into two sets, prior to and after 1992, a gradual but noticeable increase was apparent after 1992, when the technique of clear corneal incision was introduced. In a comparison of types of incision from 1992 to 2003, a significantly higher risk of endophthalmitis occurred with clear corneal incisions compared to either scleral or limbal incisions (an increase in relative risk of two-and-a-half and three times, respectively).

Two studies conducted in cadaveric rabbit and human eyes may help to explain the etiology of the apparent association between endophthalmitis and clear corneal incisions. One using optical coherence tomography showed the possibility of corneal wound gaping secondary to IOP variations in both human and rabbit eyes.6 Similarly, investigators using the Miyake viewing technique in cadaveric human eyes showed an ingress of extraocular India ink or fluid following IOP variations.7 In the latter study, four of seven eyes showed the intraocular presence of ink, after standard external manipulation in three eyes and after IOP variation alone in the fourth. These studies demonstrated a possible mechanism by which microorganisms gain access into the intraocular space during the critical early postoperative period, when the wound has not yet healed.

CONCLUSION

Endophthalmitis remains one of the most feared complications of ocular surgery. Although this review of the literature suggests that the pattern of endophthalmitis after cataract surgery is associated with the introduction and increased use of the clear corneal incision, there is no proof of a causal relationship, and inevitable bias (positive or negative) is evident in the literature. Only a large, multicenter, prospective, randomized study can answer the question of the cause of endophthalmitis after cataract surgery. In the meantime, careful wound construction with a minimal tolerance for wound leakage, the placement of sutures whenever necessary, and continued vigilance in the surveillance of infection are necessary.

Mehran Taban, MD, is an ophthalmology resident at the Cole Eye Institute of the Cleveland Clinic Foundation in Ohio. Dr. Taban may be reached at (216) 360-0193; tabanm@ccf.org.
1. Fine IH. Clear corneal incisions. Int Ophthalmol Clin. 1994;34:59-72.
2. Leaming DV. Practice styles and preferences of ASCRS members—2003 survey. J Cataract Refract Surg. 2004;30:892-900.
3. Colleaux KM, Hamilton WK. Effect of prophylactic antibiotics and incision type on the incidence of endophthalmitis after cataract surgery. Can J Ophthalmol. 2000;35:373-378.
4. Nagaki Y, Hayasaka S, Kadoi C, et al. Bacterial endophthalmitis after small-incision cataract surgery. Effect of incision placement and intraocular lens type. J Cataract Refract Surg. 2003;29:20-26.
5. Taban M, Behrens A, Mewcomb RL, et al. Incidence of acute endophthalmitis following cataract surgery or penetrating keratoplasty: a meta-analysis. Paper presented at: The 107th Annual Meeting of the AAO; November 18, 2003; Anaheim, CA.
6. McDonnell PJ, Taban M, Sarayba MA, et al. Dynamic morphology of clear corneal cataract incisions. Ophthalmology. 2003;110:2342-2348.
7. Sarayba MA, Taban M, Ignacio TS, et al. Inflow of ocular surface fluid through clear corneal cataract incisions: a laboratory model. Am J Ophthalmol. 2004;138:206-210.