Retinal toxicity of gentamicin after subconjunctival injection performed adjacent to thinned sclera

Serial Swept-Source Optical Coherence Tomography Features of Gentamicin Macular Toxicity: A Glimpse Into the Injury Cascade

The early clinical manifestations of macular infarction secondary to subconjunctival gentamicin (Gentak; Akorn, Lake Forest, IL) use in an aphakic eye were documented sequentially on swept-source optical coherence tomography (OCT) and fundus fluorescein angiography. The first recorded event after drug toxicity was macular detachment, along with disorganization of outer retinal layers in about 12 hours. The changes in inner retinal layers occurred after 36 hours had elapsed. OCT-documented initial damage to outer retinal layers could be due to the susceptibility of first order retinal neurons, followed by subsequent inner retinal layer involvement and ischemia. This helps in understanding pathogenesis of a catastrophic complication of subconjunctival gentamicin injection commonly used for endophthalmitis prophylaxis. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:456-459.].

Scleroretinal Necrosis after a Subconjunctival Injection of Gentamicin in a Patient with a Surgically Repaired Episcleral Retinal Detachment

PURPOSE

To describe a case of scleroretinal necrosis after a subconjunctival injection of gentamicin in a patient who had an episcleral retinal detachment that was surgically repaired.

METHODS

Case presentation.

RESULTS

Thinning of the sclera due to cryosurgery and the induced localized inflammatory response resulting from the surgical procedure, in addition to the effect of the sponge buckle itself, could have played an important role in accumulation and storage of gentamicin under and adjacent to the buckle after injection. The increasingly higher concentration of the drug under the buckle could have induced a greater penetration of gentamicin through the sclera, which could have been the cause of the scleral-chorio-retinal necrosis observed in this patient.

CONCLUSIONS

Attention must be given to avoid side effects from subconjunctival injection of gentamicin.

Systemic and Periocular Deliveries of Plasminogen Kringle 5 Reduce Vascular Leakage in Rat Models of Oxygen-Induced Retinopathy and Diabetes

PURPOSE

Increased retinal vascular permeability is a common complication of diabetes and a major cause of vision loss in diabetic patients. The current study is to determine the effect of plasminogen kringle 5 (K5) on vascular leakage via systemic and periocular deliveries.

METHODS

Oxygen-induced retinopathy (OIR) was generated by exposing newborn rats to 75% oxygen. Diabetes was induced in adult rats by injection of streptozotocin (STZ). Retinal vascular permeability was measured by the Evans blue-albumin leakage method.

RESULTS

Subcutaneous, intraperitoneal, subconjunctival, and retrobulbar injections and topical eyedrop application of K5 significantly reduced retinal vascular permeability in both the OIR and STZ-diabetic rat models. Compared with the periocular deliveries, systemic administration requires higher doses of K5. K5 deliveries downregulated VEGF expression in the retina.

CONCLUSIONS

K5 can reduce retinal vascular permeability through systemic and periocular deliveries. These delivery routes of K5 have therapeutic potential in the treatment of vascular leakage.

Testing retinal toxicity of drugs in animal models using electrophysiological and morphological techniques

Drugs are frequently tested for retinal toxicity in animal models in order to address applied and basic research questions. When a retinal toxicity study is designed, the researcher needs to consider several factors depending on his/her research questions. Among the factors that need to be addressed before a toxicity study is conducted are: the animal species to be used, choice of experimental (functional and/or morphological) techniques, procedure of testing, period of follow-up, and modes of data analysis. This review is a summary of 20 years' experience of studying retinal toxicity of different drugs in rabbits and rats. The use of the electroretinogram and the visual evoked potential for assessment of outer and inner retinal function, respectively, is described as well as the use of morphological techniques (histology, histochemistry, and immunocytochemistry). The advantages and limitations of functional and morphological techniques are discussed with specific examples from my experience. Recommendations for future drug toxicity studies are summarized.

Avaliação clínica da ablação uveal intravítrea com gentamicina em cães portadores de glaucoma crônico

Investigou-se, clinicamente o resultado da ablação uveal intravítrea em 13 olhos cegos de cães com glaucoma crônico unilateral. Os olhos acometidos foram submetidos à ablação uveal intravítrea, por meio de injeção na câmara vítrea de 0,5ml de sulfato de gentamicina (40mg/ml) associado a 0,3ml de fosfato de dexametasona (4mg/ml). As variáveis clinicas oftálmicas foram quali-quantificadas em escores, por até 48 semanas do pós-operatório; além de aspectos relacionados à dor, como variações do apetite e peso corporal. Nos sinais clínicos, de secreção ocular, blefaroespasmo, quemose, hifema e pigmentação, neovascularização, pannus e variações de apetite e peso corporal, não se notaram diferenças significativas entre os momentos. A ablação uveal intravítrea diminuiu a hiperemia conjuntival, porém acarretou aumento de opacidade corneana. A associação da ablação com antiinflamatórios tópico e sistêmico indicou não se tratar de procedimento doloroso.

Retinal damage caused by air-fluid exchange during pars plana vitrectomy

PURPOSE

To report two cases of retinal damage associated with air infusion during pars plana vitrectomy.

DESIGN

Observational case report.

METHODS

The authors reviewed the course of two patients who had retinal damage during par plana vitrectomy and air-fluid exchange for the treatment of macular hole and optic pit-related macular detachment, respectively. The intraoperative observations, postoperative course, and outcomes were reported.

RESULTS

As a result of high air infusion flow during air-fluid exchange, retinal damage was created in the area contralateral to the infusion port. In Case 1, an oval area of whitening was noted on the first postoperative day. This area subsequently developed into a large retinal break associated with retinal detachment. In the second case, retinal whitening was noted intraoperatively. This region of pallor resolved quickly during the early postoperative period but resulted in a corresponding inferotemporal visual field defect.

CONCLUSIONS

High infusion flow during air-fluid exchange in eyes undergoing vitrectomy surgery may result in significant retinal damage. This pressure-induced trauma initially causes retinal whitening that may be seen intraoperatively or during the early postoperative period. The region of damaged retina may develop a retinal break and detachment or a corresponding visual field defect.