Ocular Spiroplasma ixodetis in Newborns, France.

Cataract and uveitis are rare in newborns but potentially blinding. Three newborns with cataract and severe anterior uveitis underwent cataract surgery. Spiroplasma ixodetis was detected in lens aspirates using bacterial 16S-rRNA PCR and transmission electron microscopy. These findings, which suggest maternal-fetal infection, are consistent with previous experimental Spiroplasma-induced cataract and uveitis.

Bacterial tick-borne diseases caused by Bartonella spp., Borrelia burgdorferi sensu lato, Coxiella burnetii, and Rickettsia spp. among patients with cataract surgery.

BACKGROUND: Clinical data have shown that tick-borne diseases caused by Borrelia burgdorferi sensu lato, Bartonella spp., Coxiella burnetii, and Rickettsia spp. can affect the central nervous system, including the eye. The aim of this study was to establish a relationship between the incidence of cataract and evidence of bacterial infections transmitted by ticks. MATERIAL AND METHODS: Fluid with lenticular masses from inside of the eye and blood from 109 patients were tested by PCR and sequencing. Sera from patients and the control group were subjected to serological tests to search specific antibodies to the bacteria. RESULTS: Microbiological analysis revealed the presence of Bartonella sp. DNA in intraoperative specimens from the eye in 1.8% of patients. Serological studies have shown that infections caused by B. burgdorferi sensu lato and Bartonella sp. were detected in 34.8% and 4.6% of patients with cataract surgery, respectively. CONCLUSIONS: Presence of DNA of yet uncultured and undescribed species of Bartonella in eye liquid indicates past infection with this pathogen. Specific antibodies to B. burgdorferi sensu lato and Bartonella sp. are detected more frequently in patients with cataract compared to the control group. This could indicate a possible role of these organisms in the pathological processes within the eyeball, leading to changes in the lens. Further studies are needed to identify Bartonella species, as well as to recognize the infectious mechanisms involved in cataract development.

Detection of Encephalitozoon cuniculi in the feline cataractous lens.

PURPOSE: Identification of Encephalitozoon cuniculi (E. cuniculi) as a possible causative agent for cataracts and uveitis in cats. METHODS: Within a 12-month study period, cats that were presented with focal anterior cortical or mature cataract and secondary uveitis underwent a complete ophthalmic examination, complete blood count, serum biochemistry, serologic tests for E. cuniculi and tests for feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), feline leukemia virus (FeLV) and Toxoplasma gondii (T. gondii). PCR for DNA detection of E. cuniculi and T. gondii as well as cytologic examination of aqueous humor after paracentesis and phacoemulsified lens material were also performed. In addition histopathologic examination of the resected anterior lens capsule and attached lens epithelial cells was performed. Serologic testing for antibodies against E. cuniculi was also performed in 100 ophthalmologically healthy cats. RESULTS: Eleven (19 eyes) European shorthair cats with a median age of 3.5 years were included. Nine of 11 cats had bilateral cataracts, with 12/19 eyes having focal anterior cortical cataracts and 7/19 eyes having mature cataracts. In 14/19 eyes anterior uveitis was present. All cats had a positive antibody titer (1:80-1:10,000) for E. cuniculi. Encephalitozoon cuniculi DNA was detected by PCR and sequencing in 18/19 lenses and in 10/19 aqueous samples. Five tentative positive results were detected by cytologic examination. Spores were detected in 15/19 samples of lens material with histopathologic staining. Only 2/100 ophthalmologically healthy cats showed a positive antibody titer for E. cuniculi. CONCLUSION: Encephalitozoon cuniculi is a cause of focal anterior cortical cataract and anterior uveitis in cats.

Screening for multiresistant pathogens before cataract surgery / Multirezisztens kórokozók szurése szürkehályog-mutét elott

Összefoglaló. Bevezetés: A multirezisztens kórokozók által okozott fertozések komoly gondot okoznak. Szemészeti szempontból az ebbe a körbe tartozó meticillinrezisztens Staphylococcus aureus (MRSA) baktérium bír kiemelkedo jelentoséggel. Célkituzés: Multirezisztens kórokozók irányában cataractamutét elott álló betegektol mintavétel és adatelemzés. Módszer: 257, cataractamutét elott álló beteg esetében végeztünk multirezisztens kórokozók szurésére vizsgálatot a conjunctivazsákból. A mikrobiológiai tenyésztés során multirezisztens kórokozóra pozitív eredményt adó betegek esetében a preoperatív kórtörténetet és az általános kíséro betegségeket feltártuk és elemeztük. Eredmények: A minták 17 beteg esetében multirezisztens kórokozóra pozitívak voltak. 11 esetben szisztémás rizikófaktorokat is találtunk. A pozitív betegeknél a mutétet csak a felszabadító mikrobiológiai eredmények birtokában végeztük el. A dekolonizált betegeknél ezt követoen a szakmai protokoll normális antibiotikumprevencióját alkalmaztuk. A 257 beteg 6,6%-ában találtunk multirezisztenskórokozó- és 5%-ában MRSA-pozitivitást. Posztoperatív endophthalmitis nem fordult elo. Következtetés: A cataractamutéteknél alkalmazott antibiotikus endophthalmitisprevenció multirezisztens kórokozóra pozitív betegeknél kevéssé hatékony lehet. Ezért javasolt a veszélyeztetett betegek multirezisztens kórokozókra történo szurése és dekolonizációja. Orv Hetil. 2021; 162(3): 106-111. INTRODUCTION: Infections caused by multiresistant pathogens may have serious consequences. In ophthalmological practice, methicillin-resistant Staphylococcus aureus (MRSA) is the most important multiresistant pathogen. OBJECTIVE: We took samples for multiresistant pathogens from patients assigned for cataract surgery. METHOD: We carried out multiresistant pathogen screening from conjunctival sac in 257 patients, who were assigned for cataract surgery. Preoperative case history and concomitant systemic diseases were evaluated in patients, who turned out to be positive for multiresistant pathogens during the screening procedure. RESULTS: The samples were positive for multiresistant pathogens in 17 patients. In the case history of 11 multiresistant pathogen positive patients, previous systemic risk factors could be explored. Multiresistant pathogen positive patients were operated only after the decolonisation. After the decolonisation, the normal antibiotic prevention was used before the surgery. Multiresistant pathogen positive was 6.6%, MRSA positive was 5% of the 257 patients. There were no cases of endophthalmitis in any of these patients. CONCLUSION: Endophthalmitis prevention with antibiotics, according to the guidelines, may not be efficient in multiresistant pathogen positive patients. Therefore, it is advisable to screen multiresistant pathogens and decolonisation at risk patients before cataract surgery. Orv Hetil. 2021; 162(3): 106-111.

Molecular Mimicry between Betaine Aldehyde Dehydrogenase of Leptospira and Retinal Dehydrogenase 1 of Human Lens: A Potential Trigger for Cataract Formation in Leptospiral Uveitis Patients.

Purpose: Rapidly progressing cataract is one of the ocular manifestations in leptospiral uveitis patients. We examined whether molecular mimicry between the leptospira antigens and lens proteins exists that could result in cataract in these patients.Methods: Immunoblot analysis using patient sera was done with proteins from normal lens and cataract lens from leptospiral uveitis patients and the cross-reacting lens proteins were identified by mass spectrometry analysis.Results: Retinal dehydrogenase 1 and crystallins (α-B, α-A2, ß-B2), were recognized by the antibodies in the serum of leptospiral uveitis patients. And, retinal dehydrogenase 1 is homologous to the leptospiral protein, betaine aldehyde dehydrogenase.Conclusions: Leptospiral uveitis patient serum contains antibodies that cross-react with multiple lens proteins that have a role in maintaining lens transparency. And, these antibodies could act as a potential trigger for cataractogenesis.

Streptococcus pneumoniae endophthalmitis: clinical settings, antibiotic susceptibility, and visual outcomes.

Streptococcus pneumoniae endophthalmitis is clinically more severe, more difficult to treat, and carry a higher risk of vision loss, evisceration, or enucleation. This study is to investigate the clinical settings, antibiotic susceptibility, and visual outcomes of S. pneumoniae endophthalmitis at a tertiary referral center in Taiwan. S. pneumoniae endophthalmitis was diagnosed in 38 eyes of 38 patients. The main clinical features were postcataract endophthalmitis (n = 13, 34%) and endophthalmitis associated with corneal ulcer (n = 12, 32%), trauma (n = 6, 16%), endogenous etiology (n = 4, 11%), trabeculectomy (n = 2, 5%), and pterygium excision-related scleral ulcer (n = 1, 3%). Presenting visual acuity ranged from counting fingers to no light perception. Pars plana vitrectomy with intravitreal antibiotics was performed in 17 eyes (39%) in primary or secondary treatments. S. pneumoniae isolates were susceptible to vancomycin (38/38, 100%), penicillin (37/38, 97%), ceftriaxone (37/38, 97%), cefuroxime (12/15, 80%), levofloxacin (13/15 ,87%), and moxifloxacin (15/17, 88%). Final visual acuity was better than 20/400 in 3 of 38 eyes (8%), 5/200 to hand motions in 3 eyes (8%), and light perception to no light perception in 32 eyes (84%). Ten eyes (26%) underwent evisceration or enucleation. Although S. pneumoniae isolates were susceptible to vancomycin, S. pneumoniae endophthalmitis had a very poor visual prognosis.

ToRCH-screening in pediatric cataract revisited: A North Indian tertiary care centre study.

Purpose: To analyze and report ToRCH-serology screening profile (Toxoplasma gondii [TOX], rubella [RV], cytomegalovirus [CMV], and herpes simplex virus [HSV-I/II]) in pediatric cataract. Methods: In this prospective analytical study, 1,026 consecutive children were screened, of which 46 children with clinically diagnosed congenital (n = 26) and developmental cataract (n = 20) were included. Post-traumatic and familial cataracts were excluded. Sera of all children were tested both qualitatively and quantitatively for IgG/IgM-antibodies against ToRCH agents in a sequential manner. Results: Overall, IgM/IgG-seropositivity against ≥1 ToRCH agent was reported in 91.3% (42/46) children. IgM (±IgG) positivity against ≥1 ToRCH agent was reported in 26.08% (12/46) children (nine congenital and three developmental cataract; P = 0.18), which included 8.7% (4/46) children reported positive against ≥2 agents. Finally, 13% (6/46) children were reported to be sero-clinical-positive (three were infants and three were> 1 year age, P = 0.55; five congenital and one developmental cataract, P = 0.21). Either alone or combined, RV attributed to the majority (50%; 6/12) of the IgM (±IgG) and sero-clinical-positive (50%; 3/6) children. None of the children were HSV-II IgM-positive. Laboratory-confirmed congenital rubella syndrome was reported in 4.3% (2/46) children. One sero-clinical-positive infant with rare coexisting bilateral persistent fetal vasculature was also reported. IgG-alone positivity was reported highest with CMV in 67.4% (31/46) children, whereas 43.4% (20/46) children were found nonimmune to RV. Conclusion: The current study emphasizes the need to interpret ToRCH-screening in pediatric cataract with caution. Interpretation should include both serial qualitative and quantitative assays in tandem with clinical correlation to minimize the diagnostic errors. Clinicians should remain vigilant regarding sero-clinical-positivity in older children too who might pose a threat to the spread of infection.

A defined medium for a fastidious Spiroplasma.

A defined medium (H-1) was developed for cultivation of the suckling mouse cataract agent, Spiroplasma mirum, a fastidious member of the class Mollicutes that causes cataracts and chronic brain infection in inoculated neonate mice. The H-1 medium was used to show the importance of sphingomyelin as a growth factor for the culture of the spiroplasma in vitro. The growth of Spiroplasma mirum and the pathology it induces in sphingomyelin-rich tissues in vivo may be related to this dependency.

[Study of different methods in reducing conjunctival bacteria before cataract surgery].

OBJECTIVE: To study the conjunctival bacteria flora in eyes of patients undergoing cataract surgery and determine the efficacy of reducing conjunctival bacteria with different methods. METHODS: A total of 135 eyes of 135 patients scheduled to undergo cataract surgery were randomized into 3 groups (45 each). They received topical prophylactic treatment with three different kinds of antibiotics (0.5% levofloxacin, 0.3% levofloxacin and 0.3% tobramycin). Each group was randomized into one-day group and three-day group. All the eyes underwent irrigation of fornices with 2.5% povidone-iodine (PVI) before surgery. Conjunctival cultures were obtained at various time points. RESULTS: The total positive rate of conjunctival cultures was 66.7%. The eliminating rate of conjunctival bacteria in one-day groups were 72.7%, 72.7% and 61.1% (P = 0.667) while 70.0%, 70.0% and 55.5% in the three-day groups respectively (P = 0.751). Immediately after PVI irrigation, the eliminating rate in one-day groups added up to 86.4%, 77.3% and 88.9% (P = 0.564) as compared with 90.0%, 80.0% and 66.7% in the three-day groups respectively (P = 0.749). And there was no statistically significant difference between one-day groups and three-day groups in the eliminating rate of conjunctival bacterial after the topical antibiotic application. The MIC test revealed that the antibiotic sensitivity of Gram-positive cocci (G(+)C) to levofloxacin was 94.8% versus 74.1% to tobramycin (P = 0.000) while the antibiotic sensitivity of Gram-negative bacillus (G(-)B) to levofloxacin was 94.4% versus 83.3% to tobramycin (P = 0.289). CONCLUSION: G(+)C accounts for the most among the conjunctival bacteria flora in eyes of patients undergoing cataract surgery and there is no statistically significant difference in the efficacy of reducing conjunctival bacteria between the application of topical antibiotic for one day and for three days. Both G(+)C and G(-)B retain a high sensitivity to levofloxacin. Topical antibiotic in combination with 2.5% PVI irrigation further reduces conjunctival bacteria.

A cluster of endophthalmitis caused by Mycobacterium abscessus after cataract surgery.

We report two cases of postoperative endophthalmitis after cataract surgery caused by the same strain of Mycobacterium abscessus confirmed by arbitrarily primed polymerase chain reaction, sequencing of the erythromycin ribosome methyltransferase gene and pulsed-field gel electrophoresis. The outcomes were poor despite aggressive treatments. This is the first report of nontuberculous mycobacteria as a causative pathogen for a cluster of endophthalmitis.

High-resolution genotyping of Pseudomonas aeruginosa strains linked to acute post cataract surgery endophthalmitis outbreaks in India.

BACKGROUND: Investigation of two independent outbreaks of post cataract surgery endophthalmitis identified the reservoir of epidemic strains of P. aeruginosa. METHODS: Patient isolates cultured from vitreous fluid of all the nine cases and from the peripheral devices of phacoemulsification machine were subjected to high-resolution Fluorescent Amplified Fragment Length Polymorphism (FAFLP) analysis. RESULTS: FAFLP based genotyping of the isolates confirmed nosocomial transmission. Although biochemical characterization and antibiotic susceptibility profiles grouped all the isolates together, FAFLP based genotyping revealed that, all the outbreak isolates were derived from 2 different strains, with independent origins. One group of isolates was traced to phacoprobe and the second one to the internal tubing system of the phacoemulsification machine used in cataract surgery. In silico analysis indicated possible evolution in both the clusters of P. aeruginosa isolates due to genetic polymorphisms. The polymorphisms were mapped to gene products (cell envelope, outer membrane proteins) possibly having significant role in pathogenesis. CONCLUSION: The present study is probably the first one to apply FAFLP typing successfully to investigate outbreaks of postoperative endophthalmitis (POE) in an ophthalmic setting, which was able to identify the source, and helped to make rational decisions on sterilization procedures that halted more cases of infection in these hospitals.

Pseudomonas aeruginosa endophthalmitis in a preterm infant.

Bacterial endophthalmitis is rare in the neonatal period. It occurs in susceptible individuals such as preterm infants. Pseudomonas aeruginosa, a Gram-negative bacillus, has been identified as the causative organism in more than 75% of invasive neonatal eye infections. The source may be endogenous; secondary to septicemia or exogenous, including reports of nosocomial infections and those infections arising from the birth canal. We report the case of a preterm infant who developed pseudomonas endophthalmitis, septicemia, and meningitis after a corneal abrasion.

[Changes in bacterial flora of conjunctival sac in patients prophylacticaly treated with antibiotic before cataract operation]. / Zmiany flory bakteryjnej worka spojówkowego pacjentów, u których stosowano profilaktycznie antybiotyk przed operacja zacmy.

PURPOSE: The aim of the study was to estimate changes in bacterial flora of conjunctival sac changes in patients prophylacticaly treated with different antibiotics (chloramphenicol, gentamycin, ofloxacin, norfloxacin) before cataract operation. MATERIAL AND METHODS: The studied group consisted of 166 patients hospitalized for cataract surgery. The control group consisted of 33 persons, neither treated topically with antimicrobial drugs nor suffering from infectious or inflammatory diseases. On the first day and on the operation day conjunctival swabs were obtained and typical microbiological diagnosis was performed. During hospitalization only one antimicrobial drug was administrated topically (chloramphenicol, gentamycin, ofloxacin or norfloxacin) in the studied group. RESULTS: Prophylaxis with antibiotics before cataract surgery changes bacterial flora of conjunctival sac: quantitative changes were observed most frequently, but also hospital antibiotic resistant strains were detected. None of tested antibiotics caused total elimination of conjunctival flora in all patients. CONCLUSIONS: None of the antibiotics used in our study could cause total elimination of conjunctival flora. According to our results, the most effective antibiotics in prophylaxis before eye surgery are fluoroquinolones. Some patients before eye surgery have the pathogenetic conjunctival flora not causing the disease, yet increasing the risk of postoperative endophthalmitis.

[Bacteriological contents of conjunctival sac in patients with cataract in the early post-operative period]. / Bakteriologiczna zawartosc worka spojówkowego u pacjentów z zacma we wczesnym okresie pooperacyjnym.

PURPOSE: Evaluation of conjunctival microflora in patients with cataract, during the early post-operative period. MATERIAL AND METHODS: One hundred twenty patients scheduled for cataract extraction were evaluated. In each patient, conjunctival swab was taken directly after cataract surgery and two to three days postoperatively. Following surgical procedure all patients received topical antibiotics alone or along with steroids. The agents were placed into conjunctival sac of the operated eye. Ophthalmic ointments were administered HS and eye drops QID. RESULTS: 9.2% (11 patients) of the cultures of conjunctival swabs collected right after surgical procedure were positive for growth with predominantly Gram-positive organisms, mainly Staphyloccocus spp. These, were compared with 24.2% (29 patients) of positive cultures from conjunctival swabs collected two to three days later. 4.2% of the latter were also positive when taken in the operating room, immediately after a surgical procedure. The remaining 20.0% of positive cultures swabbed two to three days after surgery were resulted from the contamination of conjunctival sac with germs during the postoperative hospitalisation. CONCLUSIONS: There is a risk of early post-operative infection in patients undergoing cataract surgery. It is caused by the appearance of microflora in the conjunctival sac.

[Bacterial flora of conjunctival sac in patients with cataract. Methods of disinfection and evaluation of their efficiency]. / Mikroflora worka spojówkowego u chorych z zacma--metody dezynfekcji i ocena ich skutecznosci.

PURPOSE: 1) To evaluate the microbacterial flora of the conjunctival sac and the sensitivity of the isolated microorganisms to 0.3% gentamicin solution and 5.0% PVP-Jodi solution, which is used to disinfect conjunctival sac. 2) To evaluate the role of the adhesive foil in prevention of the infection of the operative field. MATERIAL AND METHODS: 170 patients with senile cataract were examined. Before admission to Ophthalmology Department each patient received 0.3% gentamicin solution three times a day. All patients had their conjunctival sac disinfected with the use of 5% PVP-Jodi before surgery. Patients were divided into two groups. In the first group (120 patients), first samples were taken on admission to the Ophthalmology Department. Next in the day of the procedure, in the operation room--first before and second after disinfection of conjunctival sac. Adhesive foil was not used in this group. In the second group (50 patients), we used adhesive foil before surgery and samples were taken before and after disinfection of conjunctival sac. RESULTS: On admission, positive cultures were obtained in 40.0% cases. Most of the bacterial flora were Gram-positive bacteria. The number of the positive cultures before disinfection with 5.0% PVP-Jodi solution diminished to 5.8%, compared with positive results obtained on admission to the Ophthalmology Department. Secondary infection of the conjunctival sac has been revealed in 10% after disinfection with the use of the 5.0% PVP Jodi. It was due to bacterial flora coming from the skin and limbs of the lids (in the group without adhesive foil), whereas positive samples were obtained in 2.0% in the group where adhesive foil was used. CONCLUSIONS: 1) Gentamicin significantly reduces the amount of bacterial flora in conjunctival sac in patients before cataract surgery. 2) Adhesive foil is efficient to protect operative field from infection.

Encephalitozoon cuniculi causes focal anterior cataract and uveitis in dogs.

Three mongrel dogs, aged 10 months (case 1), 14 months (case 2) and 7.5 years (case 3), were presented because of ophthalmologic disorders of 4 months, 6 months and 7 years duration, respectively. All three dogs were offspring of stray dogs from Hungary and Serbia and had positive serum antibody titres against Encephalitozoon (E.) cuniculi. The two young dogs showed unilateral, the older dog bilateral chronic anterior uveitis with posterior synechia and focal anterior cortical cataract. The fundi that could be evaluated developed focal tapetal hyporeflective lesions in the course of the disease. Dogs 1 and 2 underwent removal of the lens via phacoemulsification. PCR of the lens material was positive for E. cuniculi strains IV and II, respectively. In dog 2 findings suggestive of microsporidia were detected underneath the anterior lens capsule by immunohistochemical staining. In all cases medical treatment consisted of systemic fenbendazole, prednisolone, and topical anti-inflammatory drugs, and additional brinzolamid/timolol for dog 3. For the time being all cases (follow up 23 months, 6 months and 3 months, respectively) are still on topical anti-inflammatory therapy. It is concluded that E. cuniculi infections can cause cataract and chorioretinal lesions in dogs.

The microbial flora in extended-wear soft contact-lens wearers.

Of 857 cultures of material collected from the eyelids, conjunctivae, and contact lenses of 51 extended-wear soft-contact-lens wearers, 44 (5%) grew potential pathogens. The aphakic patients wearing contact lenses had fewer recoverable pathogens (24 of 295 or 8%) than a group of preoperative cataract patients (63 of 295 or 21%). On five occasions, positive cultures accompanied clinical symptoms, and on three occasions, repeated cultures grew the same potential pathogen.

Spontaneous cataract absorption in patients with leptospiral uveitis.

AIMS: To describe the occurrence of spontaneous cataract absorption in patients with leptospiral uveitis. METHODS: The records of patients with seropositive leptospiral uveitis seen in the uveitis clinic at Aravind Eye Hospital between January 1994 and December 1997 were reviewed retrospectively. RESULTS: During the 4 years of the study, 394 eyes of 276 patients with seropositive leptospiral uveitis were identified. Of these, 54 eyes (13.7%) of 41 patients (14.9%) had a final visual acuity of 20/40 or worse attributable to cataract formation. Of these 54 eyes, 41 eyes (75.9%) had visually significant cataract on their first visit to the uveitis clinic, and 13 eyes (24.1%) were noted to have cataract 1-6 months after presentation. Spontaneous absorption was observed in 10 eyes (18.5%) of eight patients (19.5%), and occurred from 6 weeks to 18 months, with a median of 5 months, after the onset of cataract. Of 12 035 consecutive, non-leptospiral, non-traumatic, uveitic, control patients seen during the same 4 years of the study, none showed spontaneous cataract absorption. CONCLUSION: Spontaneous cataract absorption occurs in a significant number of patients with leptospiral uveitis, and appears to be unique to this form of non-traumatic uveitis.

Comparison of 5% povidone-iodine solution against 1% povidone-iodine solution in preoperative cataract surgery antisepsis: a prospective randomised double blind study.

BACKGROUND/AIM: Povidone-iodine (PI, Betadine) is routinely used as a preoperative topical antiseptic in cataract surgery as it has been shown to reduce the incidence of postoperative endophthalmitis. However, the concentration used clinically is variable. In vitro studies have shown that PI is paradoxically more effective at lower concentration. This study was undertaken to determine if this effect was reproducible in vivo. METHODS: A prospective randomised double blind study was carried out in the ophthalmic theatre in a district general hospital. 105 patients attending for routine cataract surgery were randomly allocated to have their conjunctival fornices irrigated preoperatively with either PI 1% (group A) or PI 5% (group B). Conjunctival swabs were taken, in identical fashion, both before and 1 minute after irrigation. The number and species of bacterial colonies cultured from each swab was counted. The difference in the median number of bacterial colonies from pre-irrigation to post-irrigation cultures was then compared between the groups. RESULTS: Bacterial cultures were gained from 100 patients (33 male, 67 female, mean age 74 years, range 30-95 years). Group B (5% PI) showed a decrease in median colony forming units (CFU) pre-irrigation from 100 to 40 CFU post-irrigation (a drop of 60%). This was greater than in group A (1% PI) where the reduction was 120 CFU pre-irrigation to 100 CFU post-irrigation (a drop of 16.7%) (Mann-Whitney test, p<0.05). At higher initial bacterial loads (CFU pre-irrigation >1000), the difference in median between the two groups became larger as the number of pre-irrigation bacteria increased. In group B pre-irrigation CFU reduced from 3340 to 110 post-irrigation (a drop of 96.7%) compared with group A: 5000 CFU pre-irrigation to 3000 post-irrigation (a drop of 40%) (Mann-Whitney test, p=0.0014). CONCLUSION: Despite in vitro evidence of higher bactericidal efficacy of PI at more dilute concentrations, 5% PI is more effective than 1% PI in decreasing the human conjunctival bacterial flora in vivo, particularly in the presence of heavier initial bacterial load.