Descemet's Stripping Endothelial Keratoplasty: An Effective Treatment for Toxic Anterior Segment Syndrome with Histopathologic Findings

Toxic anterior segment syndrome (TASS): A review and update

Toxic anterior segment syndrome (TASS) is an acute, sterile, postoperative inflammatory reaction of the anterior segment without vitreous involvement, following an uncomplicated and uneventful ocular surgery, having broad and multiple etiologies. The symptoms of decreased visual acuity and ocular discomfort generally occur within the first 12-48 h after intraocular surgery. The clinical signs include prominent limbus-to-limbus corneal edema, anterior chamber cells, aqueous flare, fibrinous inflammation, and/or keratic precipitates. There can be sight-threatening complications of TASS, such as permanent corneal decompensation, intractable glaucoma, and cystoid macular edema. The causes of TASS are emerging and being reported, so are the newer treatment options for managing the inflammation and its complications. Prevention guidelines for TASS are being updated, and a traceability system for surgical instruments and intraocular fluids used during the surgery is being perpetually developed. It is important to recognize TASS and start treatment on an immediate effect. Hereby, we review the literature on TASS, emphasizing its etiology, pathophysiology, management, prognosis, complications, and the importance of prevention as well as prompt recognition.

Cataracts

94 million people are blind or visually impaired globally, and cataract is the most common cause of blindness worldwide. However, most cases of blindness are avoidable. Cataract is associated with decreased quality of life and reduced life expectancy. Most cases of cataract occur after birth and share ageing and oxidative stress as primary causes, although several non-modifiable and modifiable risk factors can accelerate cataract formation. In most patients, phacoemulsification with intraocular lens implantation is the preferred treatment and is highly cost-effective. There has been an increase in the use of comprehensive cataract surgical services, including diagnoses, treatment referrals, and rehabilitation. However, global inequity in surgical service quality is still a limitation. Implementation of preoperative risk assessment, risk reduction strategies, and new surgical technologies have made cataract surgery possible at an earlier stage of cataract severity with the expectation of good refractive outcomes. The main challenge is making the service that is currently available to some patients accessible to all by use of universal health coverage.

Cases of toxic anterior segment syndrome after primary pterygium surgery

PURPOSE

Toxic anterior segment syndrome (TASS) is an acute, sterile, inflammatory reaction of the anterior segment after intraocular surgeries. We aimed to report an outbreak of TASS which occurred following pterygium surgeries.

METHODS

A case series.

RESULTS

Four eyes of four patients developed TASS associated with formaldehyde after uneventful primary pterygium surgery with conjunctival autograft. No patients reported pain; all patients demonstrated diffuse corneal edema, epithelial defects, and anterior chamber inflammation without hypopyon, fibrin formation, and vitreous involvement on the first postoperative day. TASS diagnosis was made based on clinical findings. All patients were treated with hourly topical 1% prednisolone acetate (Pred Forte, Allergan, CA), moxifloxacin 0.5% (Vigamox, Alcon, TX), and 0.24% of hyaluronic acid (Artelac complete, Bausch & Lomb). Oral steroid (prednisolone 1 mg/kg) was added on the first week and gradually tapered over weeks. None of the affected corneas improved spontaneously. Best-corrected visual acuity ranged from 20/25000 to 20/200 in the second month after surgery. Keratoplasty was scheduled for all patients.

CONCLUSIONS

This is the first study to present TASS cases after pterygium surgery. Clinicians should be aware of TASS that can emerge after an extraocular surgery. In our analysis, since 2% formaldehyde was used by the operating room personnel for cleaning and sterilizing reusable ocular instruments, it was thought that formaldehyde was the most likely cause.

Descemet Membrane Endothelial Keratoplasty in Toxic Anterior Segment Syndrome: A Case Series

PURPOSE

To evaluate the outcomes of Descemet membrane endothelial keratoplasty (DMEK) in patients with toxic anterior segment syndrome (TASS).

METHODS

Thirteen eyes of 13 patients who underwent DMEK for endothelial decompensation secondary to TASS were retrospectively reviewed. A comprehensive ocular examination including best-corrected visual acuity (BCVA), slitlamp biomicroscopy, intraocular pressure measurement, fundus evaluation, and measurement of central corneal thickness were performed in all patients at preoperatively and postoperatively.

RESULTS

There were 8 men and 5 women, with an average age of 56 ± 19 years. The mean follow-up was 8.7 ± 3.5 months. The time interval between the onset of TASS and DMEK was 4.9.±6.6 months (range, 1.5-26 months). Twelve of 13 grafts were clear at last visit. The mean preoperative BCVA was 20/666 (range, hand motion to 20/200), and the mean BCVA was 20/36 (range, hand motion to 20/20) at the postoperative last visit (P = 0.003). The decrease in mean pachymetry from preoperative (768 ± 69 μm) to postoperative last visit (523 ± 71 μm) was statistically significant (P < 0.001).

CONCLUSIONS

DMEK seems to be a safe and an effective treatment option in eyes with TASS-related endothelial decompensation.

Report of a Cluster of Cases of Toxic Anterior-segment Syndrome After Implantation of a Specific Intraocular Lens Model

PURPOSE

To report a cluster of cases of toxic anterior-segment syndrome (TASS) in eyes implanted with a specific foldable acrylic intraocular lens (IOL) model.

DESIGN

Retrospective case series.

METHODS

The medical records were reviewed for 7 eyes of 4 patients diagnosed with TASS after cataract surgery at Shimane University and Matsue Red Cross Hospital between July and November 2020.

RESULTS

Among the 162 eyes implanted with the Lentis Comfort/LS-313 MF15 IOL, acute anterior chamber (AC) inflammation with fibrin formation developed 1-15 days after uneventful surgeries in 7 (4.3%) eyes (cataract surgery alone, n=4 eyes; combined cataract and minimally invasive glaucoma surgery, n=3 eyes). Other than local steroid use, fibrin membrane removal, YAG laser membranotomy, pars plana vitrectomy, and AC washout were performed to treat inflammation and/or secondary angle closure due to pupillary obstruction.

CONCLUSION

We experienced a cluster of TASS cases in eyes implanted with the Lentis Comfort/LS-313 MF15 IOL in a short period of time. To our knowledge, this is the first report of TASS associated with this IOL.

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-an updated review

Background

Toxic anterior segment syndrome (TASS) can be a rare complication of anterior segment surgery. Here we reviewed the most recent advances in the understanding of TASS.

Methods

English articles related to TASS were retrieved from “PubMed” using the following keywords; “toxic anterior segment syndrome” or “TASS”. The authors of this paper reviewed all the retrieved literature and critical findings were summarized.

Results

The onset of TASS can vary from hours to months. The clinical manifestations are also variable. The causes of TASS are broad and continue to expand and could not be elucidated in over half of the reported cases. Prompt and thorough investigation to explore the causes of TASS is critical. Surgeons should be fully aware and updated regarding possible etiologies and make ceaseless efforts to prevent TASS. This effort begins with establishing TASS prevention protocols and regularly training surgical staff. Proper cleaning of surgical instruments is critical and should follow the guidelines set by The American Society of Cataract and Refractive Surgery TASS Task Force. When TASS occurs, sharing information with other ophthalmologists and reporting new causes is crucial for the prevention of outbreaks.

Conclusions

Anterior segment surgeons should be reminded that TASS is mostly preventable by the establishment of TASS prevention protocols, regular surgical staff training and thorough adherence to recommendations for cleaning and sterilizing intraocular surgical instruments.

Corneal edema after phacoemulsification

Phacoemulsification is the most commonly performed cataract surgery in this era. With all the recent advances in investigations and management of cataract through phacoemulsification, most of the patients are able to achieve excellent visual outcome. Corneal edema after phacoemulsification in the immediate postoperative period often leads to patient dissatisfaction and worsening of outcome. Delayed onset corneal edema often warrants endothelial keratoplasty. This review highlights the etiopathogenesis, risk factors, and management of corneal edema in the acute phase including descemet's membrane detachment (DMD) and toxic anterior segment syndrome. Various investigative modalities such as pachymetry, specular microscopy, anterior segment optical coherence tomography, and confocal microscopy have been discussed briefly.

Retrocorneal membranes: a comparative immunohistochemical analysis of keratocytic, endothelial, and epithelial origins

PURPOSE

To determine through the use of immunohistochemistry the origins of retrocorneal cellular and fibrillar membranes.

DESIGN

Retrospective, clinicopathologic study using surgically removed human corneal tissues.

METHODS

Clinical records of patients' ocular diseases and surgical procedures were reviewed. Immunohistochemical staining was performed on 5 enucleated control globes, 32 penetrating keratoplasty specimens, and 6 Descemet stripping endothelial keratoplasty specimens to analyze: (1) the normal corneal epithelium, stroma, and endothelium; and (2) stromal scars, endothelial abnormalities, and retrocorneal membranes. Paraffin sections were stained with hematoxylin and eosin, periodic acid-Schiff, and Masson trichrome methods, and immunohistochemical analyses were performed with commonly available monoclonal and polyclonal antibodies for various cytokeratins (CKs), CD34, alpha-smooth muscle actin (SMA), and vimentin.

RESULTS

Five subtypes among 28 retrocorneal membranes were characterized. Twelve fibrous (keratocytic) membranes of stromal origin had coarse collagen and immunostained negatively for all CKs, but strongly for vimentin and alpha-SMA, the last the only marker of diagnostic value. Nine metaplastic endothelium-derived membranes produced delicate collagenous matrices and immunoreacted with CK7, vimentin, and alpha-SMA. Two epithelial multilaminar or monolaminar membranes reacted with CK cocktail and wide-spectrum CK, mildly with CK7 (not observed in orthotopic surface epithelium), and negatively for alpha-SMA and vimentin. The final 2 categories were indeterminate or non-immunoreactive (3 specimens) and mixed (2 specimens).

CONCLUSIONS

Immunohistochemistry can diagnose retrocorneal membranes of different provenances reliably in most cases. Clinical correlations established that these membranes develop after serious inflammatory disorders, prolonged wounding or ulcerations, and multiple surgeries (an average of 3.4 per patient).