Immunohistochemical, functional, and anatomical evaluation of patients with idiopathic epiretinal membrane.

PURPOSE: The main purpose of this study was to perform an immunohistochemical, functional, and anatomical evaluation of patients with idiopathic epiretinal membrane (ERM). METHODS: Twenty-four specimens of idiopathic ERM from 24 consecutive patients who underwent 23 G pars plana vitrectomy for ERM and internal limiting membrane (ILM) peeling at the San Juan University Hospital in Alicante (Spain) in 2019 were analyzed. All patients underwent a complete ophthalmological examination including measurement of best corrected visual acuity (BCVA) and macular analysis by spectral-domain optical coherence tomography (SD-OCT) at the time of diagnosis and 3 months after surgery. Specific glial fibrillar acid protein antibodies (GFAP) and S100 calcium-binding protein ß (S100ß) immunostaining markers were used to identify the macroglial component of the ERM, Müller cells, and astrocytes. Ionized calcium-binding adapter molecule 1 protein (Iba1) antibodies were used as specific markers for inflammatory cells, such as microglia and macrophages. RESULTS: Mean preoperative BCVA measured with Snellen chart was 0.3 and 0.6 preoperatively and at 3 months after surgery, respectively. SD-OCT identified 15 patients (62.5%) with a disruption of the outer retinal hyperreflective bands. The immunohistochemical study showed the presence of Müller cells in almost all cases (91.6%), as well of abundant microglia and macrophages. Microglia and macrophages were more frequently present in earlier stages of ERM. Microglia were present in ERM independently of the outer retinal hyperreflective bands integrity as measured by SD-OCT. A greater presence of macrophages was found in those ERMs with no outer retinal hyperreflective band disruption. CONCLUSIONS: Müller cells seem to be the most frequent cell group in ERMs, with also presence of microglia cells and macrophages. Astrocytes were more frequently found in early stages of ERMs. Microglia and macrophages were most frequent in ERMs with early stage (1, 2, or 3) than in advanced stages (4).

Prophylactic effect of brimonidine to minimize the incidence of subconjunctival hemorrhage in the early postoperative period after 23G pars plana vitrectomy.

BACKGROUND: Several studies have investigated and demonstrated the prophylactic effect of brimonidine drops in preventing subconjunctival hemorrhage in some microincisional ophthalmic surgeries, such as intravitreal injections or cataract surgery. However, there are no previous studies investigating this prophylactic effect after 23G microincisional vitreoretinal surgery. AIM: The aim of the current study was to determine whether subconjunctival hemorrhage after 23G pars plana vitrectomy (PPV) could be prevented with the use of prophylactic topical brimonidine. METHODS: This was a phase III, prospective, interventional, randomized, controlled single-center clinical trial with a follow-up of 2 weeks. A total of 77 eyes (mean age: 68.4 ±â€„10.7 years) undergoing 23G PPV were included and randomized into two groups: group 1 including 41 patients receiving prophylactic preoperative treatment with brimonidine, and group 2 (control group) including 36 patients not receiving this prophylactic treatment. Differences in terms of number of conjunctival quadrants affected with subconjunctival hemorrhage were evaluated in each of the follow-up visits. RESULTS: The presence of subconjunctival hemorrhage was similar in both groups the first days after surgery (p > 0.05). At the last visit (10-14 days after surgery), this condition was significantly more frequent in control group where there was a significant difference, being more frequent in the control group (7.3% vs 28.6%, p = 0.022). The number of conjunctival quadrants affected was also similar in both groups, except for the last visit in which most of the patients treated with brimonidine (92.7%) showed no bleeding compared to 71.4% in control group. No effect on the efficacy of brimonidine treatment of the presence of blood hypertension, diabetes, and antiplatelet or anticoagulant treatment was observed. CONCLUSION: Brimonidine seems to be a useful option to decrease subconjunctival hemorrhage after microincisional vitreoretinal surgery or improve its resolution during the first postoperative week. This finding should be mainly due to the vasoconstrictor effect of brimonidine. TRIAL REGISTRATION: EudraCT, 2012-002895-15 (registered 19 December 2012); https://www.clinicaltrialsregister.eu/ctr-search/search?query=2012-002895-15.