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Retinal Physician

Article

Bacterial Sequestration by Conjunctival Mucous

Removal prior to transconjunctival procedures may lower bacterial load.

By: Steven R. Bodine, MD, Charles W. Mango, MD
Retinal Physician September 1, 2020 Vol 17, Issue September 2020 Page(s): 32-33

Related

Endophthalmitis rates following intraocular injections can be greater than 0.1% and can be less than 0.001%.1-3 Prior to injection, ophthalmologists will attempt to sterilize the ocular surface with an iodine-containing solution and sometimes with antibiotics. Viscous topical anesthetics may sequester the surface bacteria from the effects of the iodine.4,5 Conjunctival mucous (CM) may also do the same.

PATIENTS AND METHODS

This study adheres to the principles of the Declaration of Helsinki. Ethics committee approval was not sought because there were no modifications to the surgical techniques the patients underwent. All participants in this study provided consent. Ten consecutive patients receiving intraocular injections of an anti-vascular endothelial growth factor drug, who had visible mucous on their conjunctiva, had their CM and their conjunctiva (after mucous removal) cultured.

Twenty minutes prior to the intraocular injection, we irrigated each patient’s superior and inferior cul-de-sacs as well as the cornea with several drops of neomycin/polymyxin B sulfates/gramicidin ophthalmic solution (Bausch + Lomb). Five minutes later, we irrigated the superior and the inferior cul-de-sacs as well as the cornea with proparacaine hydrochloride 0.5% ophthalmic solution (Bausch + Lomb) followed immediately by several drops of tetracaine hydrochloride 0.5% ophthalmic solution (Bausch + Lomb). Five minutes later, we repeated this irrigation with tetracaine hydrochloride 0.5% ophthalmic solution (Bausch + Lomb).

A few minutes prior to injection, we irrigated the superior and inferior cul-de-sacs and the cornea with several drops of a 5% povidone-iodine solution (Betadine 10% povidone-iodine topical solution from Purdue Products) mixed 50/50 with Eye Wash sterile isotonic buffered solution (Altaire).

We then separated the eyelids with a sterilized Alphonso newborn eye speculum (Storz). We placed several more drops of the 5% povidone-iodine solution on the eyeball. One minute later, we gently rolled a culture swab (BBL CultureSwab Plus Collection & Transport System for Aerobes & Anaerobes; Copan) over the inferior bulbar conjunctiva as the patient looked superiorly. If there were visible strands of mucous bridging the eye and the culture swab, we slowly rotated the culture swab in order to wind the mucous around the swab. We labeled the first culture swab “mucous.”

We then placed several more drops of the iodine solution on the eye, rolled a second culture swab over the inferior bulbar conjunctiva, and labeled it “conjunctiva.” We then administered the intraocular injection. We analyzed the data using a student’s paired t-test with a two-tailed distribution.

RESULTS

Culture swabs of the mucous and conjunctiva of 10 consecutive patients with CM visible on their bulbar conjunctiva were sent to the bacteriology lab. Bacteria grew out of 5 of the 10 applicators marked mucous. No bacteria grew out of the 10 applicators marked conjunctiva, which were taken after the mucous was mechanically removed (P=.015). The following positive bacterial cultures were obtained: Corynebacterium species; Staphylococcus epidermidis (2 patients), Staphylococcus caprae; Staphylococcus intermedius, and Propionobacterium acnes.

DISCUSSION

Many years ago, ophthalmologists doing intraocular surgery lubricated their Von Graefe knives with vegetable oils.6 The rate of endophthalmitis, although high, was less than 15%.6 One reason the infection rate was not higher is that the vitreous cavity contains a bactericidal substance that makes it a hostile environment for bacterial growth.7,8

Several studies show that even after meticulous surgical preparation, many eyes are clean but not sterilized of all bacteria.9-11 The source of this bacteria may be the meibomian glands, the conjunctiva, or saliva droplets from people talking.12,13 Mucous on the conjunctiva is also suspected of being a source of sequestered bacteria.14 Early attempts to remove CM include the use of a mild silver protein known as Argyrol or Protargol, which stains the mucous for easier removal.15 The risk of bacterial endophthalmitis is dependent on the amount of bacteria that enters the eye, the pathogenicity of that bacteria, and the immune status of the patient.16

CONCLUSION

Bacteria grew out of the CM in 5 out of 10 eyes that had been surgically prepped with topical broad spectrum antibiotic eye drops and a 5% povidone-iodine solution. After removal of the mucous (and an additional irrigation with the povidone-iodine solution) none of the conjunctival culture swabs grew out any bacteria, with a P value of .015. The removal of visible CM just prior to any transconjunctival procedure may lower the bacterial load on the ocular surface and reduce the incidence of bacterial endophthalmitis. RP

Steven R. Bodine, MD, and Charles W. Mango, MD, are retina specialists at Retina Consultations in Bronxville, New York. The authors report no related disclosures. Reach Dr. Bodine at contact@retinaconsultations.com.

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