The effect of intraoperative antibiotics in irrigating solutions on aqueous humor contamination and endophthalmitis after phacoemulsification surgery

PURPOSE: To determine the efficacy of intraoperative antibiotic use in irrigating solutions on aqueous humor contamination during phacoemulsification surgery and to evaluate the corresponding risk of postoperative endophthalmitis. METHODS: 644 eyes of 640 patients who underwent phacoemulsification surgery with foldable intraocular lens (IOL) implantation were included in this study. Preoperative conjunctival smears were taken and eyes were allocated to receive irrigating infusion fluid containing either balanced salt solution (BSS)-only (group 1; 322 eyes) or BSS with antibiotics (vancomycin and gentamycin) during surgery (group 2; 322 eyes). Bacterial contamination rates of aqueous humor samples taken in the beginning and at the end of operation were compared. Predictive factors for the development of postoperative endophthalmitis were determined by clinical and microbiologic analyses. RESULTS: The rates of culture-positivity were similar between group 1 and group 2 for both preoperative conjunctival smears and aqueous samples (p > 0.05). Aqueous samples taken at the end of operation were found to be contaminated in 68 (21.1%) eyes in group 1 and 22 (6.8%) eyes in group 2, and the difference was significant (p = 0.0001; OR = 3.65 (2.1-6.0)). Capsular rupture was associated with higher rate of contamination in both groups (p = 0.0001; OR = 7.7 and p = 0.0001; OR = 8.1). Two eyes in the BSS-only group developed postoperative endophthalmitis and these cases had posterior capsular rupture during the surgery and culture-positivity for staphylococcus epidermidis throughout the study. CONCLUSIONS: Intraoperative antibiotic irrigation decreases aqueous humor contamination during phacoemulsification. Further studies are warranted to determine the interrelationship between aqueous humor contamination and endophthalmitis in eyes with posterior capsular rupture.     

Colonization of the conjunctiva with Propionibacterium acnes before and after application of polyvidone iodine before intraocular surgery

Background: Propionibacterium acnes has been described as a causative agent of postoperative endophthalmitis. This gram-positive, immotile, non-spore-forming bacterium is highly pleomorphic and grows under conditions of low to no oxygen concentration. It is commonly found on the skin at the openings of sebaceous glands and on hairs. A near-symptomless postoperative endophthalmitis occurs particularly when Propionibacteria are enclosed in the capsular bag. We investigated to what extent the number of P. acnes in the conjunctival sac can be reduced by preoperative disinfection with polyvidone iodine (1 %). Patients and methods: A total of 261 patients with intrabulbar surgery had two conjunctival swabs taken: the first immediately prior to preoperative preparation in the operating theatre, following in-patient application of antibiotic eye drops (Polymyxin-B-sulfat, Neomycinsulfat and Gramicidin in combination); the second swab was taken after disinfection with polyvidone iodine before opening the conjunctiva. Results: Of the 261 swabs, 60 (23 %) taken prior to polyvidone iodine application were positive for Propionibacterium acnes. Following polyvidone iodine treatment, a further 5 (1.9 %) remained culture-positive. After disinfection, 55 (92 %) of the 60 positive swabs for Propionibacterium acnes remained culture-negative. Conclusions: We concluded that a significant reduction of P. acnes can be achieved by preoperative application of polyvidone iodine (1 %) (P < 0.001).      

Different techniques of extracapsular cataract extraction: bacterial contamination during surgery

This study was performed to investigate the correlation between the contamination of the anterior chamber and the technique of extracapsular cataract extraction (ECCE). Three different methods were used: uncomplicated planned ECCE, phacoemulsification involving suturing method, and sutureless technique. All patients had posterior chamber intraocular lenses implanted. Two hundred and thirty consecutive patients were included in this prospective study, and preoperative smears of the conjunctiva and intraoperative aspirates of the anterior chamber were investigated. Samples of the aqueous humor were taken at the beginning and at the end of the operation. Cultures were incubated and held for 14 days. More than 71% of the preoperative smears were contaminated by coagulase-negative staphylococci, the most commonly isolated bacteria. However, 27% of the patients had culture-positive anterior chamber aspirates intraoperatively, also with coagulase-negative staphylococci as the most frequent organisms. In no case did postoperative endophthalmitis develop. Preliminary results in a small population show that the contamination of the aqueous humor is statistically significantly less frequent if the cataract extraction is performed by phacoemulsification than if it is done without phacoemulsification. Another interesting finding is that anterior chamber contamination is not significantly more frequent, if a sutureless technique is used for cataract surgery.     

A Case of Delayed-Onset Propionibacterium acnes Endophthalmitis after Cataract Surgery with Implantation of a Preloaded Intraocular Lens

Purpose

To report a case of delayed-onset endophthalmitis after implantation of a preloaded intraocular lens (IOL) and examine the surgically removed IOL by scanning electron microscopy (SEM).

Case

A 77-year-old female underwent uneventful phacoemulsification and aspiration with preloaded silicone IOL implantation. Since intraocular inflammation unexpectedly worsened 1 month after the surgery, she was referred to our hospital. Her visual acuity was hand motion in the left eye. Hypopyon and fibrin formation were observed in the anterior chamber. A diagnosis of postoperative delayed-onset endophthalmitis was made, and vitrectomy with anterior chamber wash-out was performed. As intraocular inflammation remained unchanged postoperatively, an additional surgery with IOL removal was performed. We cultivated the surgically removed samples of aqueous humor and vitreous fluid under both aerobic and anaerobic conditions, performed 16S rDNA clone library analysis of these clinical samples, and examined the removed IOL by SEM.

Result

Inflammation subsided after the re-operation. Although cultures of aqueous and vitreous samples were negative, DNA of Propionibacterium acnes was detected in the aqueous humor. The SEM images showed that the rod bacteria and biofilm-like material formed on the tip of the IOL haptic.

Conclusion

Delayed-onset endophthalmitis may occur after uneventful implantation of a preloaded IOL. The SEM findings suggested that the tip of the preloaded IOL haptic might scratch bacteria which adhered to the tip of the injector nozzle when the IOL was inserted into the anterior chamber. In some cases with delayed-onset endophthalmitis, IOL removal is needed to eliminate the bacteria which adhere to the tip of the IOL haptic.Key Words: Endophthalmitis, Preloaded intraocular lens, Propionibacterium acnes, Scanning electron microscopy     

Flomoxef Sodium and Levofloxacin Concentrations in Aqueous Humor

Aims: We intravenously administered flomoxef sodium (FMOX) 120 minutes before cataract surgery, topically administered levofloxacin (LVFX) into the eyes four times at 30-minute intervals before surgery, and measured the aqueous humor concentrations of these agents to investigate their penetration into the aqueous humor and their efficacy in the prevention of postoperative endophthalmitis. Methods: Sixty-eight patients who underwent cataract surgery at the Department of Ophthalmology, Yokohama City University School of Medicine, or its affiliate, Kanazawa Hospital, Yokohama, were enrolled in this study. They received one or both of the following: 1.0 g FMOX via a 20-minute intravenous drip and LVFX ophthalmic solution applied four times at 30-minute intervals, both beginning two hours before the operation. Aqueous humor was aspirated from the anterior chamber and assayed for FMOX and LVFX concentrations using high-performance liquid chromatography (HPLC). Results: The mean intraoperative FMOX and LVFX concentrations in the patients' aqueous humor were 1.21 ± 0.63 μ g/ml and 0.69 ± 0.47 μ g/ml, respectively. These concentrations sufficiently exceeded the MIC90 values against Staphylococcus epidermidis, S. aureus, and Propionibacterium acnes. Conclusions: The FMOX and LVFX concentrations in the aqueous humor sampling were adequate to kill bacteria in vitro. These drugs may have efficacy in the prevention of postoperative endophthalmitis in patients undergoing cataract surgery.     

The effect of preoperative topical antibiotics in cataract surgery

PURPOSE: We studied whether topical antibiotics prevent endophthalmitis after cataract surgery. METHODS: Cefmenoxime hydrochloride (CMX) or artificial tears (AT) were randomly instilled 72 hours before surgery. Conjunctival swab samples were taken before the instillation of eye drops (1) and after the instillation of eye drops (2). Aqueous humor (3) was cultured intraoperatively. RESULTS: Positive cultures were found in the CMX group of eyes in 76.3% of (1) samples, 58.1% of (2) samples, and 6.0% of (3) samples. In the AT group of eyes, positive cultures were found in 78.6% of (1) samples, 63.8% of (2) samples, and 2.9% of (3) samples. CMX was not effective. In the CMX group of eyes, Staphylococcus epidermidis was found in 59 eyes of group (1), 5 eyes of group (2), and 0 eyes of group (3). In the AT group of eyes, S. epidermidis was found in 70 eyes of group (1), 26 eyes of group (2), and 1 eye of group (3). In the cases where S. epidermidis was decreased by CMX topical use Propionibacterium acnes was increased. CONCLUSIONS: There is a possibility that preoperative topical use of CMX can reduce S. epidermidis. On the other hand, it might increase P. acnes. Considering these results and the fact that there was no difference in effectiveness in the aqueous humor cultures, preoperative CMX topical use may not prevent postoperative endophthalmitis except for endophthalmitis due to S. epidermidis.     

A comparison of endophthalmitis after phacoemulsification or extracapsular cataract extraction in a socio-economically deprived environment: a retrospective analysis of 2446 patients

PURPOSE: To assess which cataract operation technique involves least risk of postoperative endophthalmitis, when performed in a population living in poor hygiene conditions. METHODS: This retrospective clinical study evaluated 2446 cases at the Eye Clinic of the Komotini General Hospital, Greece, between January 1998 and January 2001. RESULTS: Endophthalmitis arose in 12/1055 patients (1.13%) after extracapsular cataract extraction (ECCE) and in 8/1391 after phacoemulsification (0.57%). The mean time to onset of endophthalmitis was 23 and 73 days respectively after phacoemulsification and ECCE. This difference was statistically significant. CONCLUSIONS: Endophthalmitis develops considerably later after ECCE than phacoemulsification. Thus it would appear that hygiene conditions have a stronger effect in patients operated with the ECCE technique. In order to reduce the risk of endophthalmitis after cataract extraction in patients living in substandard conditions, phacoemulsification is proposed as preferable to ECCE.     

Preoperative gentamicin eye drops and chlorhexidine solution in cataract surgery. Experimental and clinical results

PURPOSE: 1) To evaluate the effects on the conjunctival flora of gentamicin ophthalmic eye drops 0.3%, given four times in 45 minutes, and a conjunctival rinse with 10 ml chlorhexidine 0.05% solution. 2) To investigate retrospectively the rate of endophthalmitis after cataract operations when these antimicrobials were applied preoperatively. METHODS: Seventy-six patients undergoing standard phacoemulsification operations were enrolled in the experimental part of the study. Cultures were taken preoperatively, 5 minutes after prophylaxis with either chlorhexidine or gentamicin. To assess the combined effects of chlorhexidine and gentamicin, cultures were taken after the cataract operation. Hospital charts were reviewed for cases of endophthalmitis in 1994 and 1995, when this prophylactic protocol was used at the St Erik's cataract surgery department. RESULTS: The conjunctival microflora was significantly suppressed by chlorhexidine rinsing alone (p = 0.001), while no other significant anti-bacterial effects were observed with the experimental prophylaxis. The endophthalmitis rate was 32/12. 806 operations (0.25%). CONCLUSIONS: Topical rinsing with chlorhexidine solution suppresses conjunctival flora in the short term. Combined topical chlorhexidine and gentamicin prophylaxis does not eliminate postoperative endophthalmitis caused by gram-positive bacteria.     

Bacterial contamination of the anterior chamber during phacoemulsification cataract surgery

PURPOSE: To determine the incidence of bacterial contamination of the anterior chamber after phacoemulsification cataract surgery with intraocular lens (IOL) implantation. SETTING: Department of Ophthalmology, Royal Prince Alfred Hospital, Sydney, Australia. METHODS: Ninety-eight consecutive eyes of 96 patients having phacoemulsification cataract surgery with IOL implantation were included in this prospective study. Two intraoperative anterior chamber aspirates were obtained from each patient, 1 taken at the start and the other at the conclusion of surgery. In addition, preoperative and postoperative conjunctival swabs were acquired. The 4 specimens were cultured using direct culturing techniques under aerobic and anaerobic conditions for 14 days. No preoperative antibiotics were used. RESULTS: The incidence of intraoperative anterior chamber contamination was 0% (95% confidence interval, 0%-3.7%) as all intraoperative anterior chamber samples proved culture negative. Sixty-five percent of the preoperative conjunctival swabs were positive for growth, with corynebacteria, coagulase-negative staphylococci, and Propionibacterium acnes being the most frequently cultured organisms. Sixteen percent of the postoperative conjunctival swabs were positive for growth, with corynebacteria and coagulase-negative staphylococci being the most common bacteria. One patient developed culture-positive postoperative endophthalmitis; using pulsed-field gel electrophoresis for further typing, the implicated Staphylococcus epidermidis was indistinguishable from that isolated from the patient's preoperative conjunctival swab. CONCLUSIONS: The bacterial contamination rate of the anterior chamber after phacoemulsification and IOL implantation was extremely low. Additional findings support the conjunctiva as being a primary source of bacteria causing postoperative endophthalmitis as well as the ability of povidone-iodine to reduce the conjunctival bacterial load.     

Bacterial contamination of anterior chamber during IOL surgery

PURPOSE: To study the nature and frequency of bacterial contamination during cataract surgery. METHODS: The preoperative smears from the conjunctiva and anterior chamber (AC) fluid aspirates during extra-capsular cataract surgery (ECCE) with posterior chamber intraocular lens (PCIOL) implantation in 40 eyes were analysed for aerobic and anaerobic bacteria. Any change in the bacterial strains isolated before and after cataract surgery was also studied. RESULTS: AC fluid aspirates were positive for bacteria in 15 eyes (37.5%). Coagulase-negative Staphylococcus was the most common aerobe (39.4%) and Propionibacterium acnes the most common anaerobe. Of the 15 cases with positive AC fluid cultures, 6 showed an organism in the AC aspirate different from the conjunctival smear. CONCLUSION: Clinically there was no endophthalmitis in any of the eyes. Factors such as preoperative antibiotic use, the antibacterial properties of aqueous, or low inoculum size could explain this. The preoperative conjunctival smear may not be useful in predicting the AC fluid contamination or outcome of cataract surgery.     

Evaluation of bacterial contamination rate of the anterior chamber during phacoemulsification surgery using an automated microbial detection system

AIM:To assess the incidence of anterior chamber bacterial contamination during phacoemulsification surgery using an automated microbial detection system (BacT/Alert).METHODS:Sixty-nine eyes of 60 patients who had uneventful phacoemulsification surgery, enrolled in this prospective study. No prophylactic topical or systemic antibiotics were used before surgery. After antisepsis with povidone-iodine, two intraoperative anterior chamber aqueous samples were obtained, the first whilst entering anterior chamber, and the second at the end of surgery. BacT/Alert culture system was used to detect bacterial contamination in the aqueous samples.RESULTS: Neither aqueous samples obtained at the beginning nor conclusion of the surgery was positive for microorganisms on BacT/Alert culture system. The rate of bacterial contamination during surgery was 0%. None of the eyes developed acute-onset endophthalmitis after surgery.CONCLUSION:In this study, no bacterial contamination of anterior chamber was observed during cataract surgery. This result shows that meticulous surgical preparation and technique can prevent anterior chamber contamination during phacoemulsification cataract surgery.     

Understanding the Interactions Between the Ocular Surface Microbiome and the Tear Proteome

PurposeThe purpose of this study was to explore the interplay between the ocular surface microbiome and the tear proteome in humans in order to better understand the pathogenesis of ocular surface-associated diseases.MethodsTwenty eyes from 20 participants were included in the study. The ocular surface microbiome was sequenced by whole-metagenome shotgun sequencing using lid and conjunctival swabs. Furthermore, the tear proteome was identified using chromatography tandem mass spectrometry. After compositional and functional profiling of the metagenome and functional characterization of the proteome by gene ontology, association studies between the ocular microbiome and tear proteome were assessed.ResultsTwo hundred twenty-nine taxa were identified with Actinobacteria and Proteobacteria being the most abundant phyla with significantly more Propionibacterium acnes and Staphylococcus epidermidis in lid compared to conjunctival swabs. The lid metagenomes were enriched in genes of the glycolysis lll and adenosine nucleotides de novo and L-isoleucine biosynthesis. Correlations between the phylum Firmicutes and fatty acid metabolism, between the genus Agrobacterium as well as vitamin B1 synthesis and antimicrobial activity, and between biosynthesis of heme, L-arginine, as well as L-citrulline and human vision were detected.ConclusionsThe ocular surface microbiome was found to be associated with the tear proteome with a role in human immune defense. This study has a potential impact on the development of treatment strategies for ocular surface-associated diseases.     

Clinical outcomes and costs of cataract surgery performed by planned ECCE and phacoemulsification

Purpose: To compare clinical outcomes and costs of cataract surgery between patients operated with standard extracapsular extraction (ECCE) and those undergoing phacoemulsification. Setting: Patients from the Ophthalmology Department of a teaching hospital in Barcelona (Spain) scheduled for cataract surgery, not combined with any other ophthalmic procedure. Methods: A retrospective analysis has been performed on a database of 1046 patients undergoing ECCE and phacoemulsification. The outcome measures used were: surgical complications, visual acuity and costs of surgery and of follow-up. Overall rate of all complications and postoperative visual acuity were compared between the two groups, adjusting for age, preoperative visual acuity, medical and ocular comorbidity. Results: 31.9% of the patients (334) underwent phacoemulsification, and 68.1% (712) underwent ECCE. Patients undergoing phacoemulsification presented a frequency of intra- and postoperative complications lower than those undergoing ECCE (odds ratio 0.57, 95%Cl 0.37–0.87 and 0.66, 95%Cl 0.46–0.96, respectively), specifically for intraoperative iris trauma (3.1% vs 0.3%, p = 0.004), residual posterior capsular opacity (2% vs 0.3%, p = 0.035) and postoperative corneal edema (7.4% vs 3.6%, p = 0.016). Costs of intervention and follow-up were lower for phacoemulsification compared with ECCE (23.9% and 14%, respectively). But global costs were slightly higher for phacoemulsification (4.87%), due to supply costs, which were more than twice those ofECCE. Conclusions: Phacoemulsification, when performed by an experienced surgeon, has better clinical outcomes than planned extracapsular extraction, and costs may be lower since supply costs are expected to decrease as the phacoemulsification technique becomes more widespread. This revised version was published online in July 2006 with corrections to the Cover Date.     

Aqueous humor induces lymphatic regression on the ocular surface

PurposeThis study is to investigate the potential effect of aqueous humor on already formed lymphatic vessels of the ocular surface including the conjunctiva and the cornea.MethodsAqueous humor harvested from fresh bovine or murine eyeballs were used in the study. It was injected into the subconjunctival space of Prox-1-GFP (green fluorescent protein) transgenic mice. Pre-existing conjunctival lymphatics were observed in vivo using our advanced live imaging system. Additionally, ex vivo tissue cultures were performed in aqueous humor with normal conjunctival tissues or inflamed corneas with newly formed lymphatic vessels. Time lapse images were taken by an advanced live cell imaging system with an incubator. Moreover, human primary microdermal lymphatic endothelial cell culture system was employed to evaluate the effect of aqueous humor on lymphatic tube regression in vitro.ResultsAqueous humor induced lymphatic regression in both normal conjunctiva and inflamed corneas. It also led to the regression of formed lymphatic tubes by the lymphatic endothelial cells in vitro.ConclusionsThis study provides the first direct and real time live imaging evidence showing that aqueous humor induces lymphatic regression. Further investigation promises for divulging new mechanisms and therapeutic strategies to treat lymphatic diseases that occur both inside and outside the eye.     

The incidence of ptosis following extracapsular and phacoemulsification surgery: comparison of two prospective studies and review of the literature

We prospectively compared 120 patients who underwent either phacoemulsification or extracapsular cataract (ECCE) surgery to establish the incidence of postoperative ptosis between the two techniques. Of the 120 patients, 60 underwent ECCE (unpublished data 1989) and 60 had phacoemulsification. Data was collected prospectively on upper and lower margin reflex distance, upper lid skin crease and levator function, preoperatively and 6 weeks postoperatively. Photographs were taken pre and postoperatively and examined by a blinded observer. At 6 weeks, ptosis was present in 18% of ECCE patients compared with 0% in the phacoemulsification group. By changing from ECCE to phacoemulsification the incidence of postoperative ptosis has reduced. The possibility to induce postoperative ptosis remains, potential mechanisms are discussed.     

Oculocardiac reflex in phacoemulsification: Peribulbar vs topical anesthesia

Purpose:This study compares the vital parameters and pain experienced during phacoemulsification under peribulbar and topical anesthesia to determine the incidence of OCR.Methods:One hundred six patients are enrolled for phacoemulsification in a prospective and randomized study. Fifty-two patients undergo surgery in a peribulbar block (Group PB) and 54 in topical anesthesia (Group TA). Mean arterial pressure (MAP) and pulse rate are recorded during a preoperative check-up and at four other steps of surgery. Pain experienced during surgery and on a postoperative day, 5, is graded with a verbal analogue scale. OCR defined as a decrease in pulse rate by greater than 20% is calculated. Chi-square test, Fisher‘s exact test, paired t test and the comparison of means give the statistical analysis. A value of P < 0.05 was taken as significant.Results:MAP readings at baseline versus MAP at other steps of surgery show a trend towards rising with a P value of < 0.05 in both groups. Pulse rate measured at all steps of surgery versus baseline pulse rate in Group TA shows P < 0.05. OCR is present in nine patients in peribulbar block verses eleven patients in topical anesthesia with P value of 0.687. The pain scores using verbal analogue scale were higher in Group TA compared with Group PB with a P < 0.0001.Conclusion:Oculocardiac reflex can occur during phacoemulsification under both peribulbar block and topical anesthesia, and the difference is not significant.     

Acute postoperative endophthalmitis caused by Actinomyces neuii.

PURPOSE: To describe a case of acute postoperative endophthalmitis caused by Actinomyces neuii after uncomplicated phacoemulsification with posterior chamber intraocular lens implant. METHODS: Interventional case report. A 58-year-old male underwent phacoemulsification, right eye, with posterior chamber intraocular lens implant. On postoperative day 6, he presented with pain, redness, and decreased visual acuity, right eye, and was found to have endophthalmitis. RESULTS: Vitreous cultures revealed the gram-positive, anaerobe Actinomyces neuii. After appropriate intraocular, periocular, topical, and systemic therapy, the infection cleared, but the vision of the patient never improved as a result of a central vein occlusion. CONCLUSION: Actinomyces species can rarely cause postoperative endophthalmitis, and it should be considered in cases of severe postoperative intraocular inflammation.     

The Incidence of Ptosis Following Extracapsular and Phacoemulsification Surgery: Comparison of Two Prospective Studies and Review of the Literature

We prospectively compared 120 patients who underwent either phacoemulsification or extracapsular cataract (ECCE) surgery to establish the incidence of postoperative ptosis between the two techniques. Of the 120 patients, 60 underwent ECCE (unpublished data 1989) and 60 had phacoemulsification. Data was collected prospectively on upper and lower margin reflex distance, upper lid skin crease and levator function, preoperatively and 6 weeks postoperatively. Photographs were taken pre and postoperatively and examined by a blinded observer. At 6 weeks, ptosis was present in 18% of ECCE patients compared with 0% in the phacoemulsification group. By changing from ECCE to phacoemulsification the incidence of postoperative ptosis has reduced. The possibility to induce postoperative ptosis remains, potential mechanisms are discussed.     

Nitric oxide levels in aqueous humor after lens extraction and poly(methyl methacrylate) and foldable acrylic intraocular lens implantation in rabbit eyes

PURPOSE: To measure the nitric oxide (NO) level in the aqueous humor of rabbit eyes after common cataract surgery techniques. SETTING: Department of Ophthalmology, Military Medical University, and Department of Immunology and Immunotoxicology of Respiratory System, Clinic of Pneumonology and Allergology, Medical University of ?ód?, ?ód?, Poland. METHODS: Thirty rabbits were randomly divided into 4 groups, and surgery was performed as follows: Group 1, extracapsular cataract extraction (ECCE) and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation; Group 2, ECCE; Group 3, phacoemulsification and foldable acrylic IOL implantation; Group 4, phacoemulsification. The aqueous humor specimens were collected on days 1, 3, and 5. Nitric oxide measurements were performed indirectly with a spectrophotometer. The NO level in the aqueous humor collected before surgery served as a control group. RESULTS: In the physiological condition, the concentration of NO was 26.52 nm/dL +/- 4.86 (SD). Postoperatively, the highest NO level in each groups was as follows: Group 1, 46.26 +/- 5.23 nm/dL on day 3; Group 2, 72.46 +/- 6.94 nm/dL on day 1; Group 3, 41.04 +/- 7.31 nm/dL on day 1; and Group 4, 32.67 +/- 2.84 nm/dL on day 3. Significantly higher levels of NO (P <.05) were observed in Groups 1 and 2 at each follow-up day; in Group 3, on days 1 and 3; and in Group 4, on day 3. CONCLUSIONS: Techniques of cataract extraction caused the NO level to increase; however, phacoemulsification with a foldable IOL caused the smallest release of NO. Rapid postoperative NO changes may theoretically contribute to blood-aqueous barrier breakdown secondary to cataract surgery.