Prospective assessment of peripapillary microvasculature using optical coherence tomography angiography in para-optic intracranial and sinonasal tumors treated with proton therapy.

PURPOSE: Radiation-induced optic neuropathy (RION) is rare but may lead to blindness. The mechanisms by which this occurs include endothelial and neuronal damage, but RION has been assessed very little in the case of extraocular tumors treated with high-energy proton therapy, the use of which is expanding worldwide. We assessed peripapillary microvascular changes by optical coherence tomography angiography (OCT-A) in patients undergoing high-energy proton therapy for para-optic intracranial or head and neck tumors. MATERIALS AND METHODS: In this prospective institutional review board approved study, patients receiving>40Gy_RBE maximal PBT dose to their optic nerve between 2018 and 2020 underwent quantitative OCT-A analyses. ImageJ software was used to assess changes in the peripapillary superficial vascular complex (SVC) using vascular area density (VAD), vessel length density (VLD) and fractal dimension (FDsk). Uni- and multivariate analyses were performed. RESULTS: Of 47 patients (78 eyes) with 29±6 months of follow-up (range 18-42), 29 patients (61.7%) had previously undergone surgery and 18 (32.1%) had microvascular abnormalities prior to proton therapy. Total radiotherapy dose was the most relevant factor in decreased peripapillary microvasculature. Duration of follow-up was associated with lower VAD (P=0.005) and mean retinal nerve fiber layer (RNFLm) thickness also decreased. There was no significant correlation between OCT-A changes and mean visual defect. CONCLUSION: Peripapillary microvasculature changes may occur from tumor compression or surgery and proton therapy for extraocular tumors. OCT-A may provide quantitative and mechanistic insights into RION before the occurrence of clinical symptoms.

[High energy proton therapy for extraocular tumors, neurotrophic keratitis and functional consequence: A series of 3 cases]. / Protonthérapie haute énergie des tumeurs extra-oculaires, kératite neurotrophique et conséquence fonctionnelle : une série de 3 cas.

INTRODUCTION: High energy proton therapy (HEP) is a form of radiation therapy using protons for extraocular tumors. Its ballistic properties are theoretically advantageous, but the real impact on the surrounding ocular tissues during cerebral and ENT irradiation is poorly documented. We describe three consecutive patients with corneal damage following such irradiation. MATERIALS/METHODS: Post-proton therapy neurotrophic keratitis (NK) is defined as corneal hypo/anesthesia responsible for an alteration of corneal trophicity and graded according to the Mackie classification, in terms of a prospective ophthalmological follow-up protocol for all patients with extraocular tumors treated with HEP. RESULTS: Among 193 patients treated with HEP between 2018 and 2021 for extraocular tumors, three patients developed severe neurotrophic keratitis, i.e. 1.6% of treated patients. According to the Mackie classification, the three patients showed grade 3 NK less than one year after the conclusion of their HEP. These three patients underwent amniotic membrane grafting. They were placed on autologous serum eye drops. Two of the three patients had to be eviscerated. The dose to the cornea was greater than 50 Gray (Gy)_Relative biological effectiveness (RBE) in the three cases. DISCUSSION: The diagnosis and etiological origin of neurotrophic keratitis are often difficult to establish. In these cases, the imputability of radiation therapy, proton therapy in our cases, in the development of neurotrophic keratitis was plausible based on the dosimetry of the patients, all of whom had anterior tumors with a poor prognosis requiring high tumoricidal doses. CONCLUSION: Further studies to establish the impact of proton therapy on corneal sensitivity are necessary. However, this feedback and the multidisciplinary management of tumors can help to limit the risk of some complications of radiation therapy. Early diagnosis allows for appropriate management and could possibly minimize the anatomical and functional ocular complications of neurotrophic keratitis.

[Combined vitrectomy-lensectomy surgery with bag-in-the-lens or lens in the bag implantation: comparison of final visual acuity]. / Chirurgie combinée vitrectomie et phakoéxérèse avec implantation bag-in-the-lens (BIL) ou de sac : comparaison de l'acuité visuelle finale.

INTRODUCTION: Combined vitrectomy-lensectomy surgery is a safe and effective procedure. Nevertheless, it is frequently complicated by posterior capsule opacification and the formation of posterior synechiae. These complications can be avoided by placing a "bag in the lens" (BIL) implant. The objective of this study is to compare the visual acuity gain (VA) after combined vitrectomy-lensectomy surgery between a group implanted with the BIL technique and a group with implantation in the bag (LIB). MATERIAL AND METHODS: We included in the study all vitrectomy-lensectomy procedures for epiretinal membrane and vitreomacular traction performed between May 2013 and July 2016 at the Hospital and University Center of Caen. We compared the VA gain between the BIL group and the LIB group six months after surgery. RESULTS: A total of 33 patients were included in the study, consisting of 28 eyes in the BIL group and 8 eyes in the LIB group. The mean VA gain in the BIL group was -0.52 LogMAR (P<0.0001) and -0.56 LogMAR (P=0.0047) for the LIB group. The difference between the two groups was not significant (P=0.74). CONCLUSION: The use of the BIL technique during vitrectomy-lensectomy allows visual recovery as good as implantation within the capsular bag. In addition, this implant has the advantage of significantly reducing the occurrence of posterior synechiae and preventing anterior and posterior capsular proliferation.

Direct determination of benzalkonium chloride in ophthalmic systems by reversed-phase high-performance liquid chromatography.

High-performance liquid chromatography has been used to quantitate benzalkonium chloride (alkylbenzyldimethylammonium chloride) in complex ophthalmic formulations at or below concentration levels of 50 ppm. The method involves a one-step dilution for sample preparation and direct injection; therefore, recovery and/or conversion problems are nonexistent. The assay is quick, specific, reproducible, and simple. This new approach makes routine determinations far simpler than previous methods and is especially useful for product stability studies and quality control procedures.