Effect of immediate postoperative intracameral tissue plasminogen activator (tPA) on anterior chamber fibrin formation in dogs undergoing phacoemulsification

Comparison of Postoperative Intraocular Inflammation in Dogs Receiving Transzonular Intravitreal Triamcinolone-Moxifloxacin Versus Subconjunctival Triamcinolone After Phacoemulsification

OBJECTIVE

To evaluate the postoperative effect of transzonular intravitreal triamcinolone-moxifloxacin compared to subconjunctival triamcinolone administered during phacoemulsification in dogs.

ANIMALS STUDIED

Forty-eight dogs (96 eyes) undergoing bilateral phacoemulsification and intraocular lens implantation.

PROCEDURES

All dogs undergoing phacoemulsification and intraocular lens implantation received transzonular intravitreal triamcinolone-moxifloxacin (TITM) in one eye and subconjunctival triamcinolone (SCT) in the contralateral eye. Aqueous flare (AF), anterior chamber fibrin formation (FF), pigment precipitates (PP) on the intraocular lens, posterior capsular opacification (PCO), corneal edema (CE), and intraocular pressure (IOP) were assessed 1 day, 1 week, 2-3 weeks, 4-6 weeks, 8-12 weeks, and ≥ 3 months postoperatively.

RESULTS

There was no difference in AF over time (p > 0.05); however, at 2-3 weeks postoperatively, the average AF was statistically greater (p = 0.01) in the TITM group compared to the SCT group. At three postoperative time points, IOP was significantly different (p < 0.05) between TITM and SCT eyes, but remained within a normal reference range. In both groups, IOP significantly decreased (p < 0.05) over time.

CONCLUSIONS

In the parameters evaluated, including overall visual outcome and surgical success, no clinically relevant differences between groups were appreciable. TITM and SCT, used adjunctively to postoperative topical ophthalmic and oral anti-inflammatories, appear to be acceptable techniques for administering a local ocular corticosteroid during canine phacoemulsification, but whether they provide any synergistic or additive effect remains unclear.

Development of Postoperative Ocular Hypertension After Phacoemulsification for Removal of Cataracts in Dogs

A cataract is a disease in which the lens of the eye becomes clouded, causing a partial or complete loss of vision. Phacoemulsification (PHACO) is a modern surgical technique used in cataract surgery. Study findings: This study observed changes in intraocular pressure (IOP) after surgery in 31 dogs (48 eyes) with cataracts that visited a veterinary hospital. The procedure involved a lens extraction by PHACO and the implantation of an intraocular lens (IOL). Postoperative ocular hypertension (POH) was defined as a postoperative IOP of 25 mmHg or higher. To assess changes in IOP, IOP measurements were performed at 1, 2, 3, and 20 h, and at 1, 2, 3, 4, and 8 weeks after surgery. The IOP was found to be significantly higher at 1 (p < 0.05), 2 (p < 0.01), and 3 (p < 0.01) hours postoperatively compared with preoperatively. The IOP measurements were compared by dividing them into three groups according to the observation period. The IOP values were measured for three groups: before cataract surgery (Group A: 13.10 ± 8.29 mmHg), 1 to 3 h after cataract surgery (Group B: 17.84 ± 5.33 mmHg), and 20 h to 8 weeks after surgery (Group C: 13.71 ± 4.78 mmHg). The IOP values from 1 to 3 h after surgery (Group B) were significantly higher compared to both Group A (p < 0.01) and Group C (p < 0.001). Conclusions: It is suggested that POH occurring within 0 to 3 h after cataract surgery should be diagnosed as secondary glaucoma, and treatment should be performed accordingly.

Effects of intracameral tissue plasminogen activator injection on posterior capsular opacification, fibrin formation, and intraocular pressure in dogs after phacoemulsification

OBJECTIVE

To evaluate whether intracameral tissue plasminogen activator (tPA) injection is effective in regulating posterior capsular opacification (PCO), fibrin formation and intraocular pressure (IOP) after cataract surgery.

ANIMAL STUDIED

Prospective study involving 30 eyes of 21 dogs that underwent phacoemulsification.

PROCEDURES

Thirty eyes were randomly divided into two groups of 15 eyes (control and tPA groups). Intracameral tPA (25 μg/0.1 mL) was injected into tPA group eyes before corneal incision closure but not into the eyes of the control group. The grades of anterior fibrin formation and PCO were compared based on slit lamp biomicroscope examination at 1 and 2 weeks, 1 month, and 2-3 months postoperatively. IOP was measured using applanation tonometry every 30 min for 4 h immediately after operation and on the following morning. The IOP of the two groups at each time was compared.

RESULTS

The grade of anterior fibrin formation and that of PCO were not significantly different between the two groups at any time point (p > .05). However, the IOP of the tPA group was significantly lower than that of the control group at each point on the day of surgery (p < .05). No complications were observed with tPA injection, except for temporary hyphema (for 3 days) in one eye.

CONCLUSIONS

Although the intracameral tPA injection did not affect anterior fibrin formation and PCO, it effectively maintained normal IOP immediately after phacoemulsification. Thus, our findings provide valuable insights into the potential benefits of intracameral tPA injection in achieving immediate IOP control after phacoemulsification.

Use of recombinant tissue plasminogen activator (rTPA) for treatment of fibrin in the anterior chamber of the horse

BACKGROUND

Recombinant intracameral tissue plasminogen activator (rTPA) administration can aid clearance of fibrin from the anterior chamber.

MATERIALS AND METHODS

In this retrospective multicentre case series, the effect of intracameral rTPA administration to treat fibrin in the anterior chamber resulting from trauma or inflammatory ocular disease was evaluated. Clinical data from 30 treatments in 29 horses were obtained from medical records from 2003 to 2022. Association between time from onset of clinical signs and time for rTPA treatment to effect was studied with regression analysis.

RESULTS

Twenty-seven horses (93.1%) had no previous history of ophthalmic disease; one had an iridic cyst, and another had equine recurrent uveitis. The majority of cases were related to trauma (79.3%). Median time from the onset of clinical signs to treatment was 12 h (IQR = 4-48 h). rTPA (72% 20 µg; 24% 25 µg; 3.3% 40 µg) was administered once in all but one eye, which was treated twice. Resolution of fibrin was seen in 96.9% (29/30) of treatments. Fibrin accumulation recurred in one case but resolved 14 days after the second treatment. Complications were seen in four treatments (13.3%): moderate pain for 24 h, intracameral debris and mild intracameral haemorrhage in a horse that received 40 µg of tissue plasminogen activator. Recurrence of fibrin accumulation was absent in 96.7% of cases. Median time to effect was 20 min (IQR = 10-45 min). Time for rTPA treatment to effect was not associated with time from fibrin formation (R2 = 0.09; p = 0.11).

CONCLUSION

Intracameral rTPA treatment can be considered at 20-25 µg in 0.1 mL solution to aid resolution of fibrin accumulation.

The Effect of Intracameral Triamcinolone Acetonide on Controlling Common Complications following Phacoemulsification in Dogs

The intracameral injection of triamcinolone acetonide (TA) has achieved favorable clinical effects in controlling intraocular inflammatory reactions in humans after cataract surgery. However, the effect of this method remains unclear in veterinary practice. In this paper, 18 dogs with bilateral cataracts were randomly divided into three groups, with 6 dogs in each group. Phacoemulsification and intraocular lens implantation were performed on the 36 eyes of these dogs. A total of 0.1 mL of TA solution was injected into the oculus dexter (OD) anterior chambers. All oculus sinister (OS) anterior chambers of these dogs were used as controls. The results demonstrated that the corneal edema severity scores of the OD (1.5 mg TA) were lower than those of the OS from the 1st to 7th day after surgery, with a significant difference on the 3rd day after surgery (p = 0.033). The corneal edema severity scores in the OD (1.5 mg TA) were significantly lower than those in the OD (0.5 mg TA) on the 3rd day after surgery (p = 0.036). The aqueous humor protein concentration of the OD (1.5 mg TA) had a lower concentration than the OS on the 1st day after surgery (p = 0.004). Furthermore, on the 5th and 10th days, the aqueous humor protein concentration of the OD (1.5 mg TA) was lower than that of the OS (p = 0.038 and p = 0.044, respectively). The aqueous humor PGE2 concentration of the OD (1.5 mg TA) had a lower concentration than the OS on the 1st day after surgery (p = 0.026). The aqueous humor PGE2 concentrations in the OD (1.0 mg TA) and OD (1.5 mg TA) were lower compared to that in the OD (0.5 mg TA) on the 1st day after surgery (p = 0.041 and p = 0.037, respectively). It was demonstrated that TA-based treatment can be safely employed to effectively control common complications after phacoemulsification in dogs.

Prophylactic efficacy of intravenous paracetamol administration to reduce the incidence of post-operative ocular hypertension in dogs undergoing phacoemulsification: A pilot study

PURPOSE

To determine whether intravenous administration of paracetamol can prevent postoperative ocular hypertension (POH) in dogs following routine phacoemulsification.

METHODS

Diabetic and non-diabetic patients (total 54 dogs) undergoing unilateral or bilateral phacoemulsification were recruited to this placebo-controlled, prospective study. The control group received 1 ml/kg saline via intravenous infusion while the treatment group received 10 mg/kg paracetamol via intravenous infusion. Infusions were administered 30 min prior to surgery and repeated 12 h following initial administration. All patients received topical latanoprost at the conclusion of surgery. Intraocular pressure (IOP) was measured before premedication (baseline), and at 1 h, 3 h, 5 h and 18 h following extubation. POH was defined as an IOP above 25 mmHg (POH25). In addition, the number of patients with an IOP exceeding 20 mmHg was analyzed (POH20).

RESULTS

POH20 occurred in 33 of 54 animals (61.1%), including 19 of 25 animals (76.0%) in the control group and 14 of 29 animals (55.2%) in the treatment group. POH25 occurred in 23 of 44 animals (52.3%), including 13 of 25 animals (52.0%) in the control group and 10 of 29 animals (34.5%) in the treatment group. Paracetamol administration showed a significant positive effect on reducing the incidence of POH20 (p = .048), but not POH25 (p = .221).

CONCLUSIONS

When comparing groups, treatment with paracetamol showed a statistically significant reduction in the incidence of POH20, although no differences were observed in the incidence of POH25 between groups. Further studies are warranted to explore whether alternative drug regimes or routes of administration can provide enhanced efficacy in the prevention of POH25.

Retrospective evaluation of phacoemulsification and aspiration in 182 eyes: Visual outcomes and CDE-predictive value

OBJECTIVE

To determine the effect of cumulative dissipated energy (CDE) on complications and visual outcome following cataract surgery in dogs.

ANIMALS STUDIED

Records of 182 canine eyes that had undergone cataract surgery.

PROCEDURES

Retrospective medical record review was conducted on dogs that underwent unilateral or bilateral elective cataract surgery by a single surgeon. Preoperative variables such as age, cataract duration, and pre-existing conditions were recorded. Intraoperative variables such as intraocular lens (IOL) status, phacoemulsification time, average power, irrigation fluid volume, and CDE were recorded. Postoperative complications and visual status at last follow-up were compared to these variables.

RESULTS

Eighty-six percent of dogs were visual in one or both eyes at last follow-up (LFU) examination. Median follow-up time was 186 days postoperatively. Eyes that developed glaucoma had a significantly greater mean CDE (77.73 ± 80.11) than eyes that did not develop glaucoma (49.21 ± 38.93). Eyes that remained visual at the LFU examination had a significantly lower mean CDE (48.31 ± 37.14) than eyes that were blind at LFU (82.05 ± 82.73). Significantly lower mean CDEs were found in diabetic eyes, younger eyes, early-operated eyes (<1 month duration), and eyes with preoperative lens-induced uveitis.

CONCLUSIONS

Higher CDE may be associated with an increased risk of postoperative glaucoma and loss of vision in dogs. Cumulative dissipated energy may be a useful prognostic indicator for success of canine cataract surgery.

Inhibition of Fibrinolysis by Streptococcal Phage LysinSM1

Expression of bacteriophage lysin_SM1 by Streptococcus oralis strain SF100 is thought to be important for the pathogenesis of infective endocarditis, due to its ability to mediate bacterial binding to fibrinogen. To better define the lysin_SM1 binding site on fibrinogen Aα, and to investigate the impact of binding on fibrinolysis, we examined the interaction of lysin_SM1 with a series of recombinant fibrinogen Aα variants. These studies revealed that lysin_SM1 binds the C-terminal region of fibrinogen Aα spanned by amino acid residues 534 to 610, with an affinity of equilibrium dissociation constant (K_D) of 3.23 × 10^-5 M. This binding site overlaps the known binding site for plasminogen, an inactive precursor of plasmin, which is a key protease responsible for degrading fibrin polymers. When tested in vitro, lysin_SM1 competitively inhibited plasminogen binding to the αC region of fibrinogen Aα. It also inhibited plasminogen-mediated fibrinolysis, as measured by thromboelastography (TEG). These results indicate that lysin_SM1 is a bi-functional virulence factor for streptococci, serving as both an adhesin and a plasminogen inhibitor. Thus, lysin_SM1 may facilitate the attachment of bacteria to fibrinogen on the surface of damaged cardiac valves and may also inhibit plasminogen-mediated lysis of infected thrombi (vegetations) on valve surfaces. IMPORTANCE The interaction of streptococci with human fibrinogen and platelets on damaged endocardium is a central event in the pathogenesis of infective endocarditis. Streptococcus oralis can bind platelets via the interaction of bacteriophage lysin_SM1 with fibrinogen on the platelet surface, and this process has been associated with increased virulence in an animal model of endocarditis. We now report that lysin_SM1 binds to the αC region of the human fibrinogen Aα chain. This interaction blocks plasminogen binding to fibrinogen and inhibits fibrinolysis. In vivo, this inhibition could prevent the lysis of infected vegetations, thereby promoting bacterial persistence and virulence.