Intraocular Temperature Distribution in Eyes Undergoing Different Types of Surgical Procedures during Vitreous Surgery

Thermosensitive Intravitreal In Situ Implant of Cefuroxime Based on Poloxamer 407 and Hyaluronic Acid

The main method of treatment and prevention of endophthalmitis is a combination of intravitreal and topical administration of antibiotics, such as cefuroxime moxifloxacin or vancomycin. However, this method is ineffective due to the rapid elimination of the drug. This problem can be solved with the help of intravitreal in situ injection systems, which are injected with a syringe into the vitreous body and provide prolonged action of the drug at the focus of inflammation. Under the influence of temperature, the liquid drug undergoes a phase transition and turns into a gel after injection. This ensures its prolonged action. The study aimed to develop an intravitreal in situ cefuroxime delivery system for the treatment of endophthalmitis based on a thermosensitive biodegradable composition of poloxamer 407 and hyaluronic acid. A combination of poloxamer Kolliphor® P407, Kolliphor® P188, and PrincipHYAL® hyaluronic acids of different molecular weights was used as a delivery system. The potency of cefuroxime solid dispersion with polyvinylpyrrolidone-10000, polyethylene glycol-400, and polyethylene glycol-1500 in a 1:2 ratio was studied for prolonged action compared to cefuroxime substance. The experimental formulations were studied for the parameters of gelation temperature in a long-term test (4 months), pH, and release of cefuroxime using dialysis bags. To study the distribution parameter in the vitreous body, an in vitro model (1/13) was developed, which was a hollow agar sphere filled with 1% (w/v) polyacrylate gel. For the superior formulations, a HET-CAM test (chorioallantoic membrane test) was performed to determine the absence of irritant effects. According to the study results, a formulation containing a solid dispersion of cefuroxime:PEG-400 (1:2), the matrix of which contained 18% (w/v) Kolliphor® P407 poloxamer, 3% (w/v) Kolliphor® P188 poloxamer, and 0.5% (w/v) hyaluronic acid (1400-1800), was selected. This sample had an average gelation temperature of 34.6 °C, pH 6.7 ± 0.5, and a pronounced prolonged effect. Only 7.6% was released in 3 h of the experiment, whereas about 38% of cefuroxime was released in 72 h. No irritant effect on the chorioallantoic membrane was observed for any formulations studied.

Temperature-controlled porcine eye holder for observing intraocular temperature during cataract surgery

During cataract surgery, the intraocular temperature changes when irrigating low-temperature fluid and ophthalmic viscosurgical devices (OVDs) are inserted in the anterior chamber, and such a temperature variation affects the unfolding of the intraocular lens (IOL). A porcine eye holder was developed for simulating temperature conditions in clinical surgery by maintaining the ocular temperature close to the body temperature. An aluminum holder was designed to fit porcine eyes and maintain the ocular temperature at approximately 36 °C, while surgery was performed at a room temperature of 20 °C. Intraocular temperature was monitored using a thermocouple sensor placed close to the posterior capsule in the vitreous cavity. Temperatures and microscopic image of the anterior chamber were simultaneously recorded. With the use of the eye holder system, the intraocular temperature unstable during surgery was observed, and there were significant reductions during hydrodissection, irrigation and aspiration, OVD insertion in the capsule, and OVD removal after IOL implantation.

Electroretinographic Assessments of Macular Function after Brilliant Blue G Staining for Inner Limiting Membrane Peeling

Purpose: The purpose of this study was to determine the effect of brilliant blue G (BBG) staining of the inner limiting membrane (ILM) on macular function. Method: Fourteen eyes of 14 patients consisting of 9 men and 5 women who underwent vitreous surgery with ILM peeling were studied. The mean age of the patients was 68.8 ± 9.14 years. Three eyes had a macular hole and eleven eyes had an epiretinal membrane. The ILM was made more visible by spraying 0.25% BBG into the vitreous cavity. The macular function was assessed by recording intraoperative focal macular electroretinograms (iFMERGs) before and after the intravitreal spraying of the BBG dye. The iFMERGs were recorded three times after core vitrectomy. The first recording was performed before the BBG injection (Phase 1, baseline), the second recording was performed after the spraying of the BBG and washing out the excess BBG (Phase 2), and the third recording was performed after the ILM peeling (Phase 3). All recordings were performed after 5 min of light-adaptation and stabilization of the intraocular conditions. The iFMERGs were recorded twice at each phase. The implicit times and amplitudes of the a- and b-wave, the PhNR, and the d-wave were measured. Wilcoxon signed-rank test were used to determine the significance of differences of the findings at Phase 2 vs. Phase 1 and Phase 3 vs. Phase 1. A p value < 0.05 was taken to be statistically significant. Results: The average implicit times of the a-wave, b-wave, PhNR, and d-wave were not significantly different in Phase 1, 2, and 3. The average a-wave, b-wave, PhNR, and d-wave amplitudes at Phase 1 did not differ significantly from that at Phase 2 and at Phase 3. Conclusions: The results indicated that the intravitreal injection of BBG does not alter the physiology of the macula, and we conclude that BBG is safe. We also conclude that iFMERGs can be used to monitor the macular function safely during intraocular surgery.