Treatment of postvitrectomy fibrin formation with intraocular tissue plasminogen activator

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.

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

OBJECTIVE

To evaluate the postoperative effect of intracameral tPA (alteplase; Activase®, Genentech, San Francisco, CA), administered at immediate conclusion of phacoemulsification, on anterior chamber fibrin formation in dogs.

PROCEDURES

Forty-one dogs (82 eyes) undergoing bilateral phacoemulsification received 25 μg/0.1 mL intracameral tPA in one eye and 0.1 mL unmedicated aqueous vehicle in the contralateral eye immediately after corneal incision closure. Intraocular pressure (IOP) was measured, and severity of anterior chamber fibrin formation, aqueous flare, pigment precipitates on the intraocular lens (IOL) implant, posterior capsular opacification (PCO), and corneal edema were graded at approximately 1 week, 2-3 weeks, 4-6 weeks, 8-12 weeks, and greater than 3 months postoperatively.

RESULTS

Anterior chamber fibrin developed postoperatively in 68.3% of dogs (28/41) and 50% of eyes (41/82). In tPA-treated eyes, 53.7% (22/41) developed fibrin compared to 46.3% of control eyes (19/41). Some degree of postoperative ocular hypertension (POH) occurred in 53.7% of dogs (22/41) and 36.5% of eyes (30/82). In tPA-treated eyes, 34.1% (14/41) experienced POH compared to 39% of control eyes (16/41). Additional intracameral tPA injection was later required in 29.3% of both tPA-treated (12/41) and control eyes (12/41).

CONCLUSIONS

Administration of intracameral tPA at immediate conclusion of canine phacoemulsification had no clinically observable effect on anterior chamber fibrin incidence at any time point. tPA-treated eyes showed no prophylaxis against POH or secondary glaucoma compared to control eyes and received late postoperative tPA injections at the same frequency as control eyes.

Surgical Results for Proliferative Vitreoretinopathy

We reviewed 88 consecutive eyes that underwent vitrectomy for retinal detachment with proliferative vitreoretinopathy (PVR) and were followed a minimum of six months. A primary goal of the surgery was the meticulous trimming of the vitreous base in hopes of decreasing the incidence of post-operative reproliferation and anterior PVR. Those eyes with anterior PVR had aggressive release of vitreous base contraction (anteroposterior and circumferential) with intraocular scissors. All posterior tractional membranes were removed. All eyes received long-acting gas for postoperative retinal tamponade. Macular reattachment was achieved in 78 (88.6%) eyes. Forty-six (52.3%) obtained at least 5/200 vision. Seventeen (19%) eyes were re-operated at least once. We compared the importance of initial lens status (pseudophakic, aphakic, phakic), need for relaxing retinotomy, presence of anterior PVR, and history of previous vitrectomy on the anatomic and visual results. No single factor was responsible for a statistically significant effect on either vision or anatomic success, except for the need for a relaxing retinotomy, which carried with it a decreased chance of an eye obtaining 5/200 vision (Fisher's exact test, p = 0.03).

In vitro vitamin K3 effect on conjunctival fibroblast migration and proliferation

Purpose. To evaluate the dose effect of vitamin K₃ on wound healing mechanisms. Methods. Conjunctival fibroblasts were incubated for 24 hours. An artificial wound was made and the cells were incubated with fresh medium plus doses of vitamin K₃ to be tested. Wound repair was monitored at 0, 18, 24, and 48 hours. Proliferation was measured in actively dividing cells by [³H]thymidine uptake. Six different groups were tested: group 1/no drugs added, group 2/ethanol 0.1%, group 3/vitamin K₃ 1 mg/L, group 4/vitamin K₃ 2 mg/L, group 5/vitamin K₃ 4 mg/L, and group 6/vitamin K₃ 6 mg/L. Each experiment was carried out in triplicate and 4 times. Results. There were no differences among groups at the initial time. In vitro wound repair was slower in groups 4, 5, and 6. There were no differences between control and ethanol groups and between control and vitamin K₃ 1 mg/L groups. Fibroblast mitogenic activity was statistically decreased in all vitamin K groups; statistical differences were found among vitamin K₃ 1 mg/mL and higher doses too. In groups 5 and 6, cellular toxicity was presented. Conclusions. Vitamin K₃ is able to inhibit fibroblast proliferation. Vitamin K₃ 2 mg/L or higher doses inhibit wound healing repair, exhibiting cellular toxicity at 4 and 6 mg/L.

Intracameral recombinant tissue plasminogen activator for the treatment of severe fibrin reaction in endophthalmitis

PURPOSE

The authors sought to evaluate the efficacy of recombinant tissue plasminogen activator (r-TPA) in the treatment of severe fibrinous anterior chamber reactions secondary to endophthalmitis.

METHODS

Twelve patients with endophthalmitis associated with severe fibrinous anterior chamber reactions were enrolled in the study. Various degrees of posterior synechiae were noted in 10 of these patients. TPA (25 microg/0.05 cc) was injected into the anterior chamber through the limbus as an adjunctive treatment to intravitreal antibiotic injection. Efficacy of the treatment was judged by the rate of fibrinolysis, the lysis of posterior synechiae, and the size of the dilated pupil.

RESULTS

After application of 25 microg of r-TPA, the fibrin reaction gradually resolved in 2-14 h. The median dilated pupil size in ratio 24 h after r-TPA injection was significantly larger than before r-TPA injection (0.41 vs 0.60; P=0.002). The median difference in pupil size in ratio in patients with posterior synechiae larger than 180 degrees was significantly larger than those with posterior synechiae equal or less than 180 degrees (0.32 vs 0.09; P=0.003). At 24 h after application of r-TPA, no eye had posterior synechiae.

CONCLUSION

Intracameral injection of r-TPA may be a safe and effective method for the treatment of significant fibrin reaction in endophthalmitis and thus facilitates vitreous and fundus examinations and vitrectomy if necessary.

Retroprosthetic membranes in AlphaCor patients: risk factors and prevention

PURPOSE

To report retroprosthetic membrane (RPM) formation in association with AlphaCor and identify risk factors for their formation and strategies for prevention and management.

METHODS

Review of AlphaCor data and case histories and literature review.

RESULTS

RPMs occurred with AlphaCor in 14 (9.3%) cases. We find significant associations with systemic risk factors (race, hypertension, diabetes mellitus) rather than ocular history, but perioperative management may also be related to risk of RPM development. Histology demonstrates a fibrovascular tissue resembling scarred corneal tissue. Similar histologic findings have been reported for other devices.

CONCLUSION

Retrocorneal membranes and RPMs with earlier keratoprostheses have frequently been reported without specific identifiable causes. Diabetes is known to be associated with intraocular membrane formation. This study demonstrates that systemic factors affect the risk of RPM formation with AlphaCor. In cases identified as at greater risk of membrane formation, peri- and postoperative therapies such as steroids, non-steroidals, heparin or rTPA should be considered. In our series, several therapeutic and surgical strategies appear effective but recognizing patients at increased risk pre-operatively and using preventive measures where indicated is likely to be key to minimizing the incidence of this complication.

Low-dose tissue plasminogen activator in the management of anterior chamber fibrin formation

PURPOSE

To investigate the efficacy of tissue plasminogen activator (tPA) in the treatment of severe fibrinous anterior chamber reactions after intraocular surgery.

SETTING

Ophthalmology Department, AHEPA University Hospital, Thessaloniki, Greece.

METHODS

The study comprised routine surgical and postoperative cases selected in a nonrandomized fashion. Low-dose tPA infusion (0.2 mL of 125 microg/mL) was administered through a side-port in the anterior chamber in 25 patients with recent or long-standing fibrin formation after cataract extraction (n = 13), trabeculectomy (n = 5), combined procedure (n = 5), or penetrating keratoplasty (n = 2). Patients were treated 4 to 25 days postoperatively (mean 7 days).

RESULTS

Fibrin lysis was observed 2 to 12 hours after tPA infusion. No hemorrhage or other complications occurred, and no further treatment was necessary in any patient. Three cases of delayed partial fibrin lysis resolved with intense topical steroid treatment. There were no recurrences over the 3-month follow-up.

CONCLUSIONS

Low-dose tPA was an effective and safe method for the management of anterior chamber fibrin formation. Treatment was well tolerated and gave excellent results with no complications.

Enzymatic vitreous surgery

Enzymatic manipulation of the vitreous and vitreoretinal juncture is currently in the process of being evaluated in many centers around the world. The goals of such manipulation are either to disinsert the posterior hyaloid from the retina surface in an atraumatic, very clean, cleavage plane or, at this point, to try to disinsert the peripheral vitreous from the neurosensory retina. In addition, enzymatic manipulation of the central vitreous in terms of liquefaction has also been evaluated. Although this is certainly the beginning of this type of vitreal surgery, adjuvant or alternative, it does appear to be a new and exciting area of vitreoretinal surgery.

Tissue plasminogen activator in the treatment of vitreoretinal diseases

Tissue plasminogen activator (tPA) is a thrombolytic agent that activates plasminogen into plasmin almost exclusively in the presence of fibrin. Intraocular injection of tPA has been proposed for the treatment of vitreoretinal diseases, such as vitreous hemorrhage, postvitrectomy fibrin formation, submacular hemorrhage, retinal vascular occlusive disorders, suprachoroidal hemorrhage and endophthalmitis. Currently, intraocular tPA is only used in the treatment of postvitrectomy fibrin formation and submacular hemorrhage. For other indications, tPA has not been shown to be safe or effective. This article reviews the use of tPA in the treatment of vitreoretinal disorders.

Vitrectomy in the management of diabetic retinopathy

According to the Early Treatment Diabetic Retinopathy Study, at least 5% of eyes receiving optimal medical treatment will still have progressive retinopathy that requires laser treatment and pars plana vitrectomy. During the past decade, improvements in instrumentation and surgical techniques have allowed more difficult cases of diabetic retinopathy to be candidates for vitrectomy. However, although the thresholds for performing surgery within established indicated situations have been lowered, only a few additional indications have been established. Although vitrectomy improves the prognosis for a favorable visual outcome, preventive measures, such as improved control of glucose levels and timely application of panretinal photocoagulation, produce better results. The authors review the indications, techniques, and results of vitrectomy in the management of diabetic retinopathy.

Intraocular recombinant tissue-plasminogen activator fibrinolysis of fibrin formation after cataract surgery in children

PURPOSE

To evaluate the efficacy and safety of intracameral recombinant tissue plasminogen activator (rt-PA) application for fibrinolysis of fibrin formation after cataract surgery in children.

SETTING

Johann Wolfgang Goethe-University, Department of Ophthalmology, Frankfurt am Main, Germany.

METHODS

This study comprised 11 eyes of 10 patients aged 3 to 13 years (mean 7.2 +/- 3.68 [SD]) who developed severe fibrin formation after cataract surgery and IOL implantation despite intensive topical steroid therapy. Under general anesthesia, fibrinolysis was performed with 10 micrograms of rt-PA 7.18 +/- 2.04 days after intraocular surgery. Follow-up included slitlamp examination, tonometry, visual acuity testing, and-ophthalmoscopy. Anterior chamber flare measurements could be performed in 6 eyes.

RESULTS

Complete resolution of fibrin formations occurred in 90% of the patients in these cases, no recurrent fibrinous reaction or adverse effects were noted. In 2 eyes of the same patient with a history of juvenile rheumatoid arthritis and chronic uveitis, fibrin clot dissolution was incomplete. A recurrent fibrinous formation could be observed after 2 and 4 weeks, respectively. A beginning band keratopathy excluding the central and limbal cornea was noted after 6 and 8 weeks, respectively.

CONCLUSION

Intraocular application of rt-PA appears to be a safe and efficacious therapeutic approach in the management of severe fibrinous reactions after pediatric cataract surgery.

Proliferative vitreoretinopathy: an overview

Proliferative vitreoretinopathy (PVR) is still the most common cause of failure of surgery for rhegmatogenous retinal detachment, despite the substantial effort that has been devoted to better understanding and managing this condition during the past 25 years. Basic research has indicated that PVR represents scarring, the end stage of the wound-healing process that occurs after retinal detachment surgery. Medical treatment has been directed toward preventing inflammation, the first phase of the wound healing process, and inhibiting cell proliferation, the second phase. The 1983 Retina Society classification was modified in 1989 by the Silicone Study Group, whose classification differentiates between posterior and anterior forms of PVR and recognizes three patterns of proliferation: diffuse, focal, and subretinal. The anterior form has a worse prognosis than the posterior form, and its treatment requires more complex surgical procedures. In this review, risk factors and pathobiology of PVR are discussed, and management of PVR of various degrees of severity are considered.

Recombinant tissue plasminogen activator in cases with fibrin formation after cataract surgery: a prospective randomised multicentre study

AIMS

This study investigated the effect of tissue plasminogen activator (tPA) in patients with severe intracameral fibrin after extracapsular cataract extraction or phacoemulsification with posterior chamber intraocular lens implantation.

METHODS

A randomised prospective multicentre study was carried out in 86 patients with intraocular fibrin formation 2-8 days after cataract surgery. While the first group (n = 41) received only anti-inflammatory drugs, a single anterior chamber injection of tPA (10 micrograms) as an additional treatment to the standard was given in the second group (n = 44). On days 1, 2, 14, and 90 after randomisation, the visual acuities, slit lamp findings, and intraocular pressures were documented in standardised protocols. Efficacy of treatment was judged by the rate of fibrinolysis (primary objective), the frequency of synechiae, and central capsular fibrosis (secondary objectives).

RESULTS

The incidence and quantity of intraocular fibrin were significantly lower in the patients treated with tPA than in the control group (p < 0.05). The frequencies of synechiae were reduced by tPA injection. The capsule fibrosis noted after 3 months was significantly lower in the tPA group (p = 0.027). No ocular side effects were noted after the tPA injections.

CONCLUSIONS

Lysis of postcataract fibrin formation is accelerated and increased by a single intracameral injection of 10 micrograms tPA in addition to standard anti-inflammatory treatment. The findings suggest that the tPA injection reduces posterior capsule fibrosis, which still has to be addressed in larger study populations and with a long term follow up.

Recombinant hirudin for prevention of experimental postoperative intraocular fibrin

PURPOSE

To determine the efficacy of a specific antithrombin agent (recombinant desulphatohirudin variant 1 [Revasc, Ciba-Geigy, Ltd., Basel, Switzerland]) administered in the infusion fluid to prevent early postoperative fibrin formation in a rabbit lensectomy and vitrectomy model.

METHODS

Standard fragmatome lensectomies and core vitrectomies were performed prospectively in a masked fashion on ten control eyes with lactated Ringer's infusion and on ten eyes treated with 10 microgram of recombinant hirudin/ml in the infusate. The amounts of fibrin and hemorrhage were graded in a masked fashion by using slit-lamp examination and indirect ophthalmoscopy on postoperative days 1 through 5 and on day 7.

RESULTS

The difference in the mean grade of fibrin formed on the first postoperative day in the eyes treated with recombinant hirudin (mean, 0.9) in relation to the mean grade of fibrin in the control eyes (mean, 3.5) was statistically significant (P = .004). This difference was also significant on the second postoperative day (P = .01). None of the treated eyes developed intraoperative or postoperative hemorrhage.

CONCLUSIONS

Recombinant desulphatohirudin variant 1 is an effective inhibitor of postoperative fibrin formation in a rabbit model and is not associated with an increased risk of intraoperative or postoperative bleeding at the tested dose. This drug may be a useful adjunct in vitreous surgery for both proliferative vitreoretinopathy and the complications of proliferative diabetic retinopathy.

Breakdown of the blood-aqueous barrier after argon laser panretinal photocoagulation for proliferative diabetic retinopathy

BACKGROUND

Breakdown of the blood-aqueous barrier (BAB) after panretinal photocoagulation (PRP) was measured with a laser flare photometer over a study period of 8 weeks.

METHODS

Twenty-five eyes of 25 patients who had no previous photocoagulation and required such treatment for proliferative diabetic retinopathy (PDR) were included in the trial. They received 2000 burns (0.1-second exposure, 200 mu m spot) via a panfunduscope and 500 burns (0.1-second exposure, 500-mu m spot) with a Goldmann lens. Power levels were adjusted to produce a mild blanching of the retina. Only an argon green laser (514 nm) was used. Laser photometry was performed on both eyes at 3, 24, 48, 72, 96, and 168 hours and 8 weeks after laser treatment.

RESULTS

Including all of the eyes treated, there was a significant increase in flare value of 3, 24, and 48 hours compared with baseline (Student's t test) but not at 72, 96, and 168 hours or at 8 weeks. Peak values occurred at 24 hours. When blue and brown irides were analyzed separately, there was a significant increase in flare for blue irides compared with baseline levels at 3 and 24 hours, whereas for brown irides the increased flare was sustained at 3, 24, 48, 72, and 96 hours (Student's paired t test). In addition, when the increase in flare value from baseline was compared between blue and brown irides (pooled Student's test), there was a sustained increase at 24, 48, 72, and 96 hours for brown irides compared with blue. Clinically significant uveitis, posterior synechiae, or peripheral anterior synechiae did not develop in any of the patients.

CONCLUSIONS

Breakdown of the BAB may occur after PRP, particularly in more heavily pigmented irides. The time course of this suggests that the phenomenon is related directly to laser effects in the anterior segment, although other factors may contribute.

Tissue plasminogen activator for preserving inferior peripheral iridectomy patency in eyes with silicone oil

PURPOSE

An inferior peripheral iridectomy (IPI) was used to prevent forward migration of silicone oil in vitrectomized eyes; however, in approximately one third of eyes, the IPI closed spontaneously. Occlusion of the IPI by fibrin is believed to be an early event in permanent IPI closure by scar tissue. The authors determined whether intraocular tissue plasminogen activator (tPA) would restore and maintain IPI patency in eyes that had early occlusion of the IPI by fibrin.

METHODS

Between November 1993 and January 1995, 12 patients who underwent vitrectomy with silicone tamponade and IPI for complicated retinal detachment received an anterior chamber injection of tPA (6.25 or 12.5 microgram) for occlusion of the IPI by fibrin.

RESULTS

All 12 patients had lysis of fibrin and maintained a patent IPI at the last follow-up (124+/-95 days). One patient required multiple tPA injections for recurrent fibrin formation. In another patient, a small hyphema developed after the tPA injection, which did not occlude the IPI. When compared with the natural course in a very similar group of patients previously reported, tPA had a statistically significant beneficial effect in the maintenance of IPI patency (P = 0.040).

CONCLUSIONS

Intraocular tPA can be safely used to lyse postoperative fibrin occluding the IPI in eyes with silicone oil tamponade. Early lysis of this fibrin maintains IPI patency.

The use of tissue plasminogen activator in post-traumatic total hyphaema

BACKGROUND

We wanted to evaluate whether intracameral injection of tissue plasminogen activator (tPA) is useful in managing traumatic hyphaema.

METHODS

Two eyes with total hyphaema after a severe penetrating injury were treated with a single intracameral injection of 25 micrograms of tPA 5 and 14 days after the injury, respectively.

RESULTS

Most of the blood coagulum dissolved within 24 h, and in one of the two eyes the intraocular pressure decreased from 45 to 8 mmHg. The other eye was hypotonic. No re-bleeding or complications related to the use of tPA were noticed.

CONCLUSION

The results in these two cases suggest that tPA is a useful adjunct in managing total hyphaema.

Initial clinical experience with tissue plasminogen activator (tPA) assisted removal of submacular haemorrhage

Tissue plasminogen activator (tPA) (250 micrograms/ml) was used to facilitate removal of submacular thrombus in 15 patients. Following a three-port vitrectomy and subretinal tPA injection (0.1 ml) via a 30 gauge needle, blood was evacuated after enzymatic dissolution for 20 minutes. Two injections were required in some cases. Nine women and six men were treated (mean age 75.5 +/- 8.6 years). Duration of symptoms ranged from 2 days to 8 weeks. One case was due to a retinal macroaneurysm, the others to age-related macular degeneration. Vision improved in 13 patients and remained the same or deteriorated in 2 (mean follow-up 11 +/- 4.9 months). Well-defined subretinal neovascular membranes were identified in 2 patients and occult neovascularisation suspected in 2 others. A cataract developed in 1 case and retinal detachments in 2 others; all were treated successfully. The poor visual prognosis associated with submacular haemorrhage may be obviated by the use of the technique we describe.

Subretinal fibrosis in central serous chorioretinopathy

PURPOSE

To report unusual and heretofore unreported visually damaging manifestations of severe central serous chorioretinopathy.

METHODS

Case studies.

RESULTS

Each of six male patients (average age, 40 years) had a form of severe central serous chorioretinopathy with at least one eye containing fibrin in the subretinal space that then developed into a subretinal fibrotic scar. Scar formation was followed by a tenting up of the macula, vascularization of the fibrosis (subretinal neovascularization), or a retinal pigment epithelial rip. Four of the seven eyes with subretinal fibrosis had severe visual loss (20/400 or worse).

CONCLUSION

Subretinal fibrin and other extracellular matrix molecules appear to stimulate the retinal pigment epithelium to undergo fibrous metaplasia, which results in subretinal fibrotic scar formation and other sequelae, all of which can lead to severe visual loss.

Low-dose intraocular tissue plasminogen activator treatment for traumatic total hyphema, postcataract, and penetrating keratoplasty fibrinous membranes

Tissue plasminogen activator (tPA) has been used to treat severe postcataract and vitrectomy fibrinous membranes, but intraocular bleeding has occurred with doses of 25 micrograms or higher. We report three patients, one with nonclearing total hyphema and uncontrollable intraocular pressure and two with severe fibrinous membrane formation, who had treatment with low-dose (4 micrograms to 6 micrograms) intraocular tPA. Although the fibrinous membranes or hyphema resolved in all three patients, they recurred and bleeding that required additional treatment occurred in one patient. Intraocular low-dose tPA may minimize the risk of corneal and retinal toxicity and may be considered an alternative treatment in intractable cases. However, secondary intraocular hemorrhage can occur, and the timing between the initial vascular injury, treatment with tPA, and subsequent bleeding may reduce the risk of further hemorrhaging.

Topical treatment of postvitrectomy fibrin formation with tissue plasminogen activator

Tissue plasminogen activator (tPA) is able to dissolve any fibrin material that forms in the anterior chamber or vitreous humor. This property has been reported by various experimental studies performed in rabbits. The authors demonstrate the tPA eye drops administered to patients with postoperative hyphema, which did not respond to traditional therapy, gave rapid clearance of the clot. Following its topical administration for the first time in patients, the harmless nature of the drug is emphasized as well as its efficacy. This study indicates the promising features of this drug which deserve further investigation.

The use of tissue plasminogen activator in postvitrectomy cases

The study concerns 17 eyes which, following vitrectomy, were given an injection of 25 micrograms of tissue plasminogen activator (tPA). Of these 17 cases, ten showed a severe fibrin formation in the anterior chamber, 3 cases showed vitreous hemorrhage (one of them with hyphema), 2 had fibrin formation and cellular proliferation, while in one case tPA was injected at the end of the vitrectomy because of perisilicone proliferation and in one case because of fibrin depositions on the intraocular lens. The tPA was injected into the anterior chamber (10 eyes) or into the vitreous cavity (7 eyes). The follow-up period ranged from 4 to 15 months (mean period 9 1/2 months). Fibrinolysis was noted in the 10 cases with fibrin formation in the anterior chamber. Fibrin dissolution was achieved within 3-4 hours. None of these cases presented a recurrence throughout the follow-up period. Positive results were observed also in the case with perisilicone proliferation. On the contrary in 3 cases with postvitrectomy hemorrhage the hemorrhage persisted unchanged. Also in 2 cases with fibrin formation and cellular proliferation on the anterior and posterior surface of the iris the tPA injection proved ineffective. Both cases developed traction retinal detachment (TRD) due to anterior proliferative vitreoretinopathy (PVR). In the case with fibrin depositions on the intraocular lens the situation remained unchanged. Any complications observed in our case proved to be mild and transitory.

Intraocular tissue plasminogen activator concentrations after subconjunctival delivery

BACKGROUND

Topical application of recombinant tissue plasminogen activator (tPA) results in detectable intraocular tPA levels. The authors sought to determine whether subconjunctival delivery of recombinant tPA results in enhanced intraocular drug levels.

METHODS

One week after first performing a gas vitrectomy in each eye, the authors injected 0.4 ml of a tPA solution (1 or 10 mg/ml) subconjunctivally in one eye of 16 rabbits and 0.4 ml of sterile water in the fellow control eye. Vitreous taps were performed to obtain vitreous samples for measuring tPA concentrations. An anterior chamber paracentesis was then done for each concentration at 15, 30, and 60 minutes. Aqueous and vitreous tPA concentrations were determined using a two-site enzyme-linked immunosorbent assay (ELISA).

RESULTS

Vitreous tPA levels were higher than aqueous levels in the treated eyes. Vitreous levels averaged 7 +/- 7 ng/ml for the 1-mg/ml group (n = 7/7) and 202 +/- 230 ng/ml for the 10-mg/ml group (n = 7/8). Aqueous levels were positive in 8 of 16 samples. The authors conclude that subconjunctival delivery of tPA results in both vitreous and aqueous tPA levels.

Treatment of anterior chamber fibrin following cataract surgery with tissue plasminogen activator

Three patients who developed anterior chamber fibrinous exudates after cataract surgery were treated with tissue plasminogen activator injected into the anterior chamber. There was prompt dissolution of the fibrinous exudates and no observed complications. When fibrinous exudates occur in high-risk patients after cataract surgery, tissue plasminogen activator provides an excellent means of clearing the fibrin.

Vitrectomy in the management of diabetic eye disease

Vitrectomy techniques including endolaser photocoagulation allow visual rehabilitation in many eyes that are otherwise untreatable. Discerning the indications and timing for diabetic vitrectomy is increasingly important as the treatment of complications of diabetic retinopathy continues to undergo modification and redefinition. The most common indications for diabetic vitrectomy include: 1) severe nonclearing vitreous hemorrhage; 2) traction retinal detachment recently involving the macula; 3) combined traction and rhegmatogenous detachment; 4) progressive fibrovascular proliferation; and 5) rubeosis iridis and vitreous hemorrhage for eyes in which the media opacity has prevented adequate laser photocoagulation. Other less common indications in selected cases include dense premacular hemorrhage, ghost cell glaucoma, macular edema with premacular traction, cataract preventing treatment of severe, proliferative diabetic retinopathy, anterior hyaloidal fibrovascular proliferation, and fibrinoid syndrome with retinal detachment. The rationale and surgical objectives are discussed and results are summarized.

Hypertropia following insertion of inferiorly sited double-plate Molteno tubes

The use of double-plate Molteno tubes is well established in the management of intractable glaucoma, particularly in eyes that may have had previous surgical procedures, often involving the superior conjunctiva with subsequent subconjunctival scarring. As it is frequently the case that the area of least scarring is inferiorly, we have sited the tubes there but have found that, although this usually provides good control of intraocular pressure, successful drainage of aqueous has been associated with the development of hypertropia due to upward displacement of the globe by fluid encapsulated around the plates. We report a retrospective study of 16 eyes undergoing inferiorly sited double-plate Molteno tubes, in which 9 eyes developed significant hypertropia at a mean time after insertion of 3.5 months. Mean degree of hypertropia was 9.8 prism dioptres. The management of this complication is discussed.

Treatment of postcataract fibrinous membranes with tissue plasminogen activator

PURPOSE

The purpose of this study is to investigate the efficacy and toxicity of tissue plasminogen activator (tPA) in treatment of postcataract fibrinous membranes.

METHODS

The authors injected 25 micrograms of tPA into the anterior chamber of 52 pseudophakic eyes with moderate to severe fibrinous membranes that developed after cataract surgery.

RESULTS

Intraocular tPA injection resulted in complete fibrinolysis in 47 of 52 eyes (90%) and partial fibrinolysis in 5 of 52 eyes (10%). In cases of complete fibrinolysis, resolution of the fibrinous membrane occurred within 30 minutes in 22 of 47 eyes (47%) and within 1 hour in 25 of 47 eyes (53%). No evidence of toxicity was observed as measured by slit-lamp biomicroscopy, intraocular pressure, and corneal endothelial cell density, size, and morphology. Complications of tPA administration included periorbital pain (4 eyes), anterior chamber hemorrhage (4 eyes), and anterior chamber turbidity (3 eyes).

CONCLUSION

The authors believe that intraocular tPA is effective and safe in the treatment of postcataract fibrinous membranes.

Inhibition of intraocular fibrin formation with annexin V

Annexin V is a member of the calcium- and phospholipid-binding proteins, known to have an antithrombotic effect. For the first time, we have tested its ability to prevent intraocular postoperative fibrin formation in a standardised rabbit model and compared its effect with that of heparin. Annexin V, 20 micrograms and 60 micrograms, injected in the anterior chamber post-operatively, significantly reduced the area of the fibrin clot and its time to clearing. Annexin V appeared to be as efficient as heparin. It probably acts by preventing phospholipids from playing their role in the coagulation cascade which leads to fibrin formation. Furthermore, annexin V has an anti-inflammatory effect by protecting phospholipids from phospholipase A2 activity. Therefore, annexin V might be considered as a new therapeutic agent acting both on fibrin formation and inflammatory processes.

Dissolution of intraocular fibrinous exudate by streptokinase

In a prospective, open, pilot study, the authors evaluated the effects of intraocular injection of streptokinase on intraocular fibrin. The study was composed of nine patients in whom fibrinous exudate developed after pars plana vitrectomy. There were seven male and two female patients with a mean age of 44 years (range, 27 to 65 years). Fibrinous exudates were seen 1 to 22 days after surgery with obstruction of the view of the posterior segment. Each patient received a single intraocular injection of 1000 IU of purified streptokinase. Four hours after the streptokinase injection, complete dissolution of the fibrin was noted in each patient. There were no clinically detectable adverse effects from the intraocular administration of streptokinase. Streptokinase may be considered in the dissolution of intractable intraocular fibrinous exudates after vitrectomy.

Tissue plasminogen activator for the treatment of thromboembolism in infants and children

We report our experience with the use of tissue plasminogen activator to treat 12 infants and children with various thromboembolic states after conventional thrombolytic agents had failed. The dosage range was between 0.1 to 0.5 mg/kg per hour. Complete clot dissolution occurred in seven cases after 2 hours to 3 days of therapy. Partial clot dissolution and clinical improvement were noted in another four patients. Bleeding complications were noted in 6 of the 12 patients and included bruising, oozing from various venipuncture sites, and bleeding; these complications were controlled by clinically available means. In all cases with bleeding the dose rate was in the higher range (0.46 to 0.50 mg/kg per hour). In one patient, restlessness, agitation, and screaming were noted during administration of tissue plasminogen activator and when it was reinstituted. We conclude that tissue plasminogen activator is effective in inducing clot lysis in children. Because the effective dose appears to overlap with those causing bleeding, we recommend that a dose of 0.1 mg/kg per hour be started and increased gradually if clot dissolution does not occur, with close monitoring for bleeding.