Evaluation for endotoxin in intraocular materials used during phacoemulsification surgery using a recombinant factor C assay

OBJECTIVE

Cataract surgery remains the sole method to resolve blindness secondary to cataract formation. One complication includes fibrin web formation post-operatively. This study aimed to investigate the presence of endotoxin within materials used during cataract surgery as a possible cause of fibrin web phenomenon.

METHODS

Preservative-free epinephrine, heparin, viscoelastic devices, and intraocular lenses were collected for evaluation. Various manufacturers and manufacturing lot numbers were used when available. Viscosity of viscoelastics was reduced by incubating samples with human recombinant hyaluronidase. Intraocular product (IOL) packaging fluid was collected and stored for testing. The IOLs were then washed with a sterile balanced salt solution, incubated at 37°C for 48 h, and then fluid was collected for testing to mimic intraocular placement. Samples were tested using a commercially available rFC kit. Fluorescence was measured at time zero and after 1 h using a fluorescence microplate reader. The change in fluorescence was corrected for blank fluorescence and plotted to a standard curve.

RESULTS

Endotoxin levels were below the limit of detection (0.05 EU/mL) in all samples. Incubation of IOLs at intraocular temperature did not increase extraction of endotoxin.

CONCLUSION

Endotoxin was not identified in any tested sample, including those used in cases of fibrin web formation post-phacoemulsification. As fibrin webs are often observed episodically, it is possible that endotoxin levels may vary between batches, or that endotoxin is not related to fibrin formation.

Ophthalmic viscoelastics commonly used in cataract surgery: A microbiota investigation

PURPOSE

To survey commonly used, sterile ophthalmic viscoelastic materials used during routine cataract surgery for the presence of bacterial DNA and/or viable bacteria and endotoxin quantification.

METHODS

Samples from three different ophthalmic viscoelastic manufacturers and three different production lots per manufacturer were collected for 16 S ribosomal ribonucleic acid (rRNA) sequencing and conventional aerobic and capnophilic bacterial culture. Other samples of viscoelastic material from the same three manufacturers were collected for endotoxin quantification using a commercially available Limulus amebocyte lysate (LAL) assay. Statistical analysis was performed using Sigma Plot 14.0, and R v4.0.2.0. Differences (p ≤ .05) between sample collection sites in total DNA concentration, microbial richness, mean intra-group distances, and endotoxin quantification alongside reagent controls were evaluated.

RESULTS

Culture yielded two isolates, identified as Staphylococcus epidermidis and Bacillus megaterium. 16 S rRNA sequencing revealed no differences between brands in richness or overall composition. The most common bacterial DNA detected across all brands was Staphylococcus sp., Cutibacterium sp., Flavobacterium sp., and Lactobacillus sp. A significant difference was found between the median endotoxin concentration between Anvision and Hyvisc® viscoelastic (Anvision: 0.171 EU/mL, Hyvisc®: 0.03 EU/mL; p < .001).

CONCLUSIONS

No brand-specific differences in bacterial DNA were detected in the viscoelastic materials. Staphylococcus, Cutibacterium, Flavobacterium, and Lactobacillus were the dominant contributors to the bacterial DNA detected. Although Anvision viscoelastic samples contained significantly more endotoxin than Hyvisc® viscoelastic samples, endotoxin concentrations were below the FDA limit of 0.2 EU/mL for both manufacturers. These data further the understanding of inflammatory outcomes following cataract surgery.

Unusual Inflammatory Clinical Presentation After Cataract Surgery and that Thought-provoking Question: Is this Infection or Toxic Anterior Segment Syndrome?

PURPOSE

Toxic anterior segment syndrome (TASS) is a noninfectious anterior chamber reaction caused by ocular surgeries. It usually develops within the first 12-48 h after surgery. In case of clinical suspicion of TASS, endophthalmitis as a devastating disease should always be excluded. However, the fact that TASS and endophthalmitis can look the same, but the treatment for each is different. Therefore, distinguishing between the two conditions is an important factor in coping with both diseases. It was aimed to describe the features and clinical management that are considered when distinguishing the cause of unexpected inflammatory response after cataract surgery.

METHODS

A retrospective review of medical records of 13 patients who developed TASS in our clinic at Ege University Ophthalmology Department on three different days between July 2022 and December 2022 were included in this study. Anterior segment photographs of those 13 patients and the records of ophthalmological examinations of those patients, including best-corrected visual acuity (BCVA), ocular pressure, biomicroscopic, and fundoscopic examination, were collected. Medical data were evaluated retrospectively.

RESULTS

The mean time to onset of clinical symptoms was 27.6 h. The main complaint was pain in nine patients. The primary symptom in the remainder of the patients was blurred vision. Severe hypopyon was seen in 5 cases. Despite the presence of pain and hypopyon, patients who were treated with topical steroids were closely followed up (every 2 h) because they were consecutive patients and had relatively acute onset complaints. Inflammation was regressed after an average of 4 h. No factor causing TASS was found. The BCVA was at the minimum level of 8/10 on the 5th day of surgery.

CONCLUSION

When distinguishing TASS from endophthalmitis, severe pain, relatively late onset, hyperemia, and the presence of severe hypopyon usually lead ophthalmologists to the clinical diagnosis of endophthalmitis. However, in this study, most of the patients diagnosed with TASS had severe pain, a significant portion of them had hypopyon, and the onset of the symptoms was relatively late. Close follow-up immediately after suspicion plays a vital role in clinical diagnosis and management accordingly.

Diffuse Corneal Edema after Uneventful Pterygium Surgery: Toxic Anterior Segment Syndrome or Toxic Keratopathy?

A 29-year-old woman was referred to our department for corneal edema after uneventful pterygium excision surgery with conjunctival autografting. She was prescribed topical dexamethasone and showed a complete response within 2 weeks of treatment. Specular microscopic examination revealed severe endothelial cell loss in the operated eye. Mild corneal haze causing a decrease in vision (20/50) was observed in long-term follow-up. This steroid-responsive complication was linked to two possible etiologies: mild toxic anterior segment syndrome or povidone-iodine (PVP-I) corneal toxicity. Surgeons should be careful during pterygium surgery to completely clear PVP-I and avoid any penetration into the anterior chamber to prevent possible serious complications. When diffuse corneal edema is encountered after pterygium surgery, intense steroid treatment should be prescribed as in the present case.

Barium-induced toxic anterior segment syndrome

Toxic anterior segment syndrome (TASS) is a rapid-onset inflammation of the eye following uneventful ocular surgery. We report a case of TASS following Baerveldt glaucoma implant (BGI) surgery. Inductively coupled plasma-mass spectrometry (ICP-MS) identified barium in the eye and in the eluate from the bleb of the BGI. We attribute TASS in our patient to the dissolution of barium from the BGI and its entry into the eye, where it causes severe inflammation.

Toxic Anterior Segment Syndrome After an Uncomplicated Vitrectomy With Epiretinal Membrane Peeling

Infectious endophthalmitis is the most devastating complication of eye surgery and is associated with severe inflammation of ocular tissues. This study aimed to present a similar condition, a case of toxic anterior segment syndrome (TASS) after an uncomplicated vitrectomy. A 69-year-old woman presented with epiretinal membrane and underwent 25-gauge pars plana vitrectomy with membrane peeling in her left eye. Thirty hours after the procedure, the patient complained of increasing loss of visual acuity and a red left eye. The ophthalmic examination revealed moderate hyperemia, hypopyon and snowbanks in the anterior vitreous. Subconjunctival and topical steroids were administered, and the inflammatory symptoms resolved within 30 days. The visual acuity improved to 20/32, however, cystoid changes were noted in the macula by optical coherence tomography.  TASS should be considered a potential complication after vitrectomy. This report presents a case of TASS and discusses the differential diagnosis between TASS, infectious and non-infectious endophthalmitis.

Severe Intraocular Inflammation following Hydrophilic Acrylic Phakic Intraocular Lens Implantation in A Case with Concealed History of COVID-19: A Case Report and Literature Review

Purpose: To firstly present management of toxic anterior segment syndrome (TASS) and possible postoperative endophthalmitis (POE) after implantation of a new hydrophilic-acrylic posterior chamber (PC) phakic intraocular lens (pIOL) in a case with undeclared history of COVID-19.Methods: A 21-year-old male without known disease represented severe anterior chamber inflammation (hypopyon), poor vision and corneal edema without vitreous involvement (TASS) at 24-hours after PC-pIOL implantation for unilateral high myopia (amblyopic).Results: Preoperative best-corrected visual acuity (BCVA) was 0.2 OS (-13 diopters). At 56-hours, vitreous was involved with visual loss indicating POE. The patient confessed that he had COVID-19 1-month ago. COVID-19 immunoglobulin M/G tests were positive, while other markers were negative. Intracameral/intravitreal antibiotics were applied. BCVA was 0.15 without hypopyon at 24-hours. Cultures were negative. Final BCVA was 0.6 with normal examination.Conclusion: TASS/POE etiology could not be demonstrated in this case, whereas COVID-19-related proinflammatory systemic background could have effect on triggering/aggravating this scenario.].

Toxic anterior segment syndrome: A review

Toxic anterior segment syndrome is a surgical complication characterized by a noninfectious anterior chamber inflammatory reaction having multiple etiologies. The clinical signs (prominent limbus-to-limbus corneal edema, anterior chamber inflammation) and symptoms (decreased visual acuity, discomfort) generally occur within the first 12-48 hours after intraocular surgery. Most patients achieve good clinical and visual outcomes when there is a prompt clinical diagnosis and adequate treatment. We review the literature on toxic anterior segment syndrome, emphasizing its etiology, pathophysiology, and clinical and surgical management, as well as prognosis and sequelae. Our goal is to reduce the frequency of toxic anterior segment syndrome by highlighting the importance of prevention, early recognition, and distinguishing toxic anterior segment syndrome from infectious endophthalmitis.

Toxic Anterior Segment Syndrome Outbreak after Cataract Surgery Triggered by Viscoelastic Substance

PURPOSE:

The purpose of this study is to present toxic anterior segment syndrome (TASS) outbreak at our clinic and discuss possible causes of TASS.

MATERIALS AND METHODS:

Thirty-four eyes of 34 patients developed TASS in a consecutive 2 weeks period were included in this study. Both anterior segment and fundus examinations were performed before and after uncomplicated cataract surgery. During the follow-up period, clinical features and all possible causes were evaluated including perioperative products and processing such as sterilization technique of surgical instruments, irrigating solutions, drugs, viscoelastic substance (VES), and intraocular lens.

RESULTS:

Patients had corneal edema, anterior chamber reactions, and decreased vision. No patient had purulent secretion, chemosis, lid involvement, and pain. At first 2 postoperative days, patients treated as infectious endophthalmitis by topical and oral antibiotics and then TASS was suspected, and patients treated completely with topical steroids. Suspected cause for TASS was VES substance, 2% sodium hyaluronate which had newly been used as VES product in phacoemulsification surgery. No new case has occurred after stopped usage of this VES product.

CONCLUSION:

As far as we know, this is the largest report of TASS outbreak in the shortest period from the same clinic caused by VES. Suboptimal products of surgical materials can be the cause of TASS. Close monitoring of each surgical step and elimination of causative agent can prevent the outbreaks of TASS.

Comparison of aqueous levels of inflammatory mediators between toxic anterior segment syndrome and endotoxin-induced uveitis animal models

PURPOSE

To compare clinical findings and the aqueous levels of inflammatory mediators between toxic anterior segment syndrome (TASS) and endotoxin-induced uveitis (EIU) animal models and to evaluate the efficacy of systemic steroid pretreatment in both animal models.

METHODS

Rats were used in this study. Ortho-phthalaldehyde solution was injected into the anterior chamber to produce TASS (n=30), and lipopolysaccharide was injected into one hind footpad to produce EIU (n=30). Clinical findings were evaluated under slit-lamp examination, and the aqueous levels of prostaglandin E2 (PGE2) and tumor necrosis factor-α (TNF-α) were measured 24 hours after these procedures. Twelve of the rats in each animal model were pretreated with intraperitoneal injection of dexamethasone for 4 days before the development of TASS and EIU.

RESULTS

Corneal haze scores were significantly higher for TASS than EIU, but clinical scores for anterior uveitis were not different between the two animal models. Although aqueous levels of PGE2 were markedly increased in both animal models, PGE2 levels were significantly higher for TASS than for EIU. However, an increase in aqueous levels of TNF-α was observed only in EIU. Dexamethasone pretreatment reduced the corneal haze score and clinical score for anterior uveitis in both animal models and inhibited the increase in aqueous levels of PGE2 and TNF-α.

CONCLUSIONS

Prostaglandin E2 and TNF-α in aqueous humor seem to be regulated differently in animal models of TASS and EIU. However, dexamethasone pretreatment improved the clinical findings and inhibited the increases in PGE2 and TNF-α in both animal models.