Examination of Conjunctival and Sclera Bacterial Flora in Patients Undergoing Cataract Surgery Using Clear-Corneal Incision or Sclero-Corneal-Tunnel Technique

Abstract

Purpose: : To compare the bacterial flora of conjunctiva and sclera in patients undergoing cataract surgery using clear-corneal incision (CCI) versus sclero-corneal-tunnel (SCT) technique.

Methods: : Two-hundred and nineteen patients undergoing cataract surgery were enrolled and divided into 2 groups: 122 had clear-corneal incisions (N=122; 90 in-patients and 32 out-patients) and sclero-corneal-tunnel technique (N=97; 75 in-patients and 22 out-patients). All in-patients received antibiotic eye drops the day before surgery and all out-patients one hour before surgery as prophylaxis. Cultures of conjunctiva were obtained from the operated eye at specific time-points and inoculated into thioglycolate broth for bacterial growth.The smear in the CCI Group was taken:T1: from the no surgery eye as control at the day of surgeryT2: after povidone iodine flushing in the operation roomT3: at the end of surgeryIn the SCT Group:T1-T2 same as CCI GroupT3: of sclera at the beginning of surgeryT4: of sclera at the end of surgeryT5: of conjunctiva at the end of surgeryIdentification of organisms was performed using Vitek 2 Compact system (bioMérieux®)

Results: : In both groups, the in-patients showed a significantly higher rate of positive thioglycolate broth cultures at T1 (151/165, 92%) compared to out-patients (39/54, 72 %)(P = 0.0003). However, this difference disappeared at T2 with in-patients having 16% positive cultures and (26/165) out-patients having 13% (7/54) (P = 0.6183). In in- and out-patients from CCI groups we found a significantly reduced number of positive conjunctival cultures from 114/122 (94%) (T1) to 17/122 (14%) (T2) to 6/122 (5%) (P < 0.0001). Patients in the SCT group also showed a significant reduction from (T1) 87/97 (86%) to (T2) 15/97 (3%)(P < 0.0001) but further reductions at T3 7/97 (8%), T4 2/97 (3%), T5 3/97(4%) were not significant. The most common isolated bacteria were coagulase-negative Staphylococcus (CNS).

Conclusions: : There was no significant difference as for bacterial contamination in both techniques.In in-patients in both the CCI and SCT groups, we found a markedly increased rate of positive conjunctival cultures compared to the corresponding groups in out-patients.

Keywords: conjunctiva • cataract • sclera