Effects of mitomycin C on the rat retina

Clinical therapeutics for proliferative vitreoretinopathy in retinal detachment

Proliferative vitreoretinopathy (PVR) is an abnormal and prolonged healing response to retinal injury (retinal detachment, post retinal detachment surgery) characterised by: pre/subretinal membrane formation; retinal gliosis and retinal shortening, retinal pigment epithelium cell proliferation; and increased glial (mainly Mu¨ller cells), fibroblast and inflammatory cell (macrophage, lymphocyte) activity, leading to tractional retinal holes/breaks and multiple costly eye operations suffered by patients. PVR can cause retinal re-detachment following primary surgical intervention for rhegmatogenous retinal detachment. Vitrectomy and scleral buckling surgery are the main approaches for treating PVR complications of retinal detachment. Patients require many operations to remove the scar tissue but vision results are suboptimal, and do not meet patient expectations. Over the past 40 years, this has been one of the greatest challenges for vitreoretinal surgeons and patients. Despite previous large clinical trials of multiple candidate drug therapeutics, no proven adjunctive treatment currently exists to either prevent, reduce, or treat PVR formation in retinal detachment. Both cellular proliferation and the intraocular inflammatory response are realistic targets for adjunctive treatments in PVR. The cellular components of PVR periretinal membranes (retinal pigment epithelial, glial, inflammatory and fibroblastic cells) proliferate and are thus targets for antiproliferative agents. In recent years, several new therapeutics have been tested, and we present an updated review of the clinical therapeutics for PVR in retinal detachment.

RETINAL TOXICITY FOLLOWING PRESUMED INADVERTENT INTRAOCULAR INJECTION OF MITOMYCIN C DURING TRABECULECTOMY

PURPOSE

To describe a case of postoperative retinal toxicity following the use of mitomycin C during a routine trabeculectomy.

METHODS

Case report of a single patient who underwent complete ophthalmic examination and multimodal imaging, including color fundus photos, optical coherence tomography, fundus autofluorescence, and fluorescein angiography. The study was declared exempt by the Institutional Review Board of Northwestern University. This research followed the tenets of the Declaration of Helsinki.

RESULTS

The patient developed profound vision loss and retinal damage during the postoperative course. Posterior segment findings include loss of vascular perfusion, diffuse loss of the outer, then inner, retinal layers, and subsequent total retinal detachment.

CONCLUSION

Although mitomycin C is commonly used in glaucoma filtering surgeries, reports of postoperative posterior segment toxicity are rare. The etiology of postoperative toxicity in this case is probable inadvertent intraocular injection of mitomycin C.

Intraocular mitomycin C use in the treatment and prophylaxis of proliferative vitreoretinopathy in severe traumatic retinal detachments

PURPOSE

To evaluate the anatomic and visual outcomes of a new intraocular mitomycin c (MMC) application technique in the treatment of severe traumatic retinal detachment (RD) with advance proliferative vitreoretinopathy (PVR).

METHODS

The records of 15 eyes of 14 patients who underwent vitreoretinal surgery and intraoperative MMC application were reviewed retrospectively.

SURGICAL TECHNIQUE

After performing complicated vitreoretinal surgical procedures (Pars plana vitrectomy, PVR membrane stripping, large retinotomy/retinectomies and intraocular foreign body removal if found etc. . .) retina was attached with perfluorocarbon liquid (PFCL) and partial fluid-air exchange. Endolaser was performed. PFCL was removed to the posterior borders of retinochoroidal wounds, breaks or retinectomy sites. The remaining PFCL was enough to cover and prevent MMC contact with the posterior vital structures including optic disc, macula and underlying RPE and major vascular arcades. Ciliary epithelium and other anterior segment structures were protected from MMC contact with the use of air in the rest of the eye. Then, a 10 µg/mL concentrated MMC solution was carefully injected above the PFCL bubble until it covered PVR or potential areas of PVR development and removed after 60 s. Finally, the remaining PFCL was removed and all eyes were filled with silicone oil. The patients were followed at least 6 months after silicone oil removal. Visual and anatomic outcomes were determined during follow-up period.

RESULTS

The mean follow-up time was 19.6 ± 6 months (range 12-27 months). About 100% retinal attachment was achieved with one vitreoretinal surgery during the follow-up period. PVR was not detected around the retinal breaks or retinotomy sites in any eye. Limited macular epiretinal membrane was detected in two eyes and subsequently peeled during silicone oil removal. Preoperative visual acuities were hand motions in seven eyes and light perception in eight eyes. Nine of 15 eyes had a visual acuity of ⩾0.1 during the follow-up period. The mean preoperative visual acuity was logMAR 2.16 ± 0.15 and postoperative visual acuity was 0.80 ± 0.50 (p = 0.001). There were no additional complications related to intraoperative MMC use during follow-up period.

CONCLUSION

Temporary intraocular MMC use in vitreoretinal surgery yielded good anatomic and visual outcomes after the treatment of traumatic RDs with PVR or those with high risk of PVR development. Furthermore, MMC application appeared to prevent further PVR development after vitreoretinal surgery.

Consequences of inadvertent intravitreal Mitomycin C injection

Background

Mitomycin C (MMC) as an alkylating agent is miscellaneous an antineoplastic, antibiotic and ophthalmic agent. Here we aim to report a case of inadvertent intravitreal MMC injection instead of Avastin in case of diabetic macular edema.

Case presentation

A 53 years old woman was planned to receive intravitreal Avastin injection, but accidentally, 0.05 ml of MMC 0.2% was injected. Best corrected visual acuity (BCVA) was 20/160 before injection. After 2 days, patient was referred to a tertiary referral eye center. BCVA was hand motion at presentation. Intraocular pressure was 4 mmHg. In slit lamp exams, conjunctival injection, corneal edema, Descemet fold, anterior chamber and anterior vitreous cells were presented. Pars plana vitrectomy with peripheral vitreous shaving and silicone oil tamponade was performed. Electroretinography showed undetectable responses. Ultrasound biomicroscopy showed ciliary body shortening and detachment. Optical coherent tomography showed diffuse retinal edema the day after surgery, subretinal fluid pockets in 2 weeks, and atrophy with undetectable and intertwined layers 2 months later. Gradually, like the retina, iris became atrophic and pigments were dispersed diffusely over the lens and endothelium.

Conclusion

MMC is showed to be severely toxic to intraocular tissues. In our case, iris and ciliary body became atrophic. Ciliary body detachment induced hypotony. Moreover, MMC induces retinal necrosis and atrophy. Visual outcome is profoundly poor.

Hypoxia-dependent retinal toxicity of NLCQ-1 (NSC 709257) in BALB/c mice. Comparison with tirapazamine

Bioreductive drugs can cause retinal toxicity, mediated by extensive apoptosis in the outer retina of rodents and monkeys. In the present study, we have investigated whether or not the novel and promising hypoxia-selective cytotoxin 4-[3-(2-nitro-1-imidazolyl)-propylamino]-7-chloroquinoline hydrochloride (NLCQ-1, NSC 709257) can cause hypoxia-dependent retinal toxicity in BALB/c mice alone or in combination with cyclophosphamide (CPM), one of the anti-cancer agents that acts synergistically with NLCQ-1 against mouse tumours and human xenografts. The bioreductive agent tirapazamine (TPZ) was included for comparison purposes. Retinal damage was quantified by morphometric analysis of histological sections following IP treatment of female BALB/c mice. No retinal toxicity was observed with 10 or 22 mg/kg of NLCQ-1 or 23 mg/kg TPZ alone, whereas statistically significant retinal toxicity was observed with the higher TPZ dose of 52 mg/kg (p < 0.001). Thus, a normalized photoreceptor layer thickness (NPT) value of 0.50 ± 0.04, 0.48 ± 0.03 and 0.33 ± 0.06 was determined for untreated, NLCQ-1 and TPZ-treated mice at the highest dose, respectively. Marginal retinal toxicity was observed with the lower dose of TPZ in combination with CPM.