Marginal Full Thickness Blepharotomy for Management of Orbital Compartment Syndrome.

PURPOSE: To assess the utility of a marginal full thickness blepharotomy (MFTB) for the treatment of orbital compartment syndrome. METHODS: An experimental study design employing a cadaver model for orbital compartment syndrome was used to assess the efficacy of an MFTB. Elevated orbital compartment pressures were created in 12 orbits of 6 fresh cadaver heads. Intraocular pressure, as an analog of orbital pressure, was measured before and after inferior and superior MFTBs were performed. Statistical analysis was performed on the collected data to assess the efficacy of the procedure. RESULTS: Both procedures were found to significantly lower the orbital compartment pressure. MFTB of the inferior lateral eyelid decreased orbital compartment pressure by an average of 62.2 mm Hg (95% CI, 56.9-67.5). MFTB of the superior lateral eyelid following MFTB of the inferior lateral eyelid decreased the orbital compartment pressure by an additional average of 10.3 mm Hg (total average reduction of 72.5 mm Hg; 95% CI, 68.1-76.9). CONCLUSIONS: Orbital compartment syndrome is a time-sensitive vision-threatening emergency that requires prompt diagnosis and intervention to prevent irreversible vision loss. The authors describe the MTFB, a simple one-step procedure that when performed correctly results in a significant decrease in orbital compartment pressure, making it a viable option when canthotomy and cantholysis fails or is unable to be performed.

Longitudinal Comparison of Orbital Volumes from Enucleated Eyes with Hydroxyapatite Orbital Implant in Unilateral Retinoblastoma Patients.

PURPOSE: To compare the orbital volume between enucleated and contralateral, uninvolved orbits over a 5-year period in patients with unilateral retinoblastoma who underwent enucleation with hydroxyapatite (HA) implant placement by a single surgeon. METHODS: A retrospective review was performed on the clinical records and radiographic images of unilateral retinoblastoma patients who underwent enucleation with primary HA implantation from 2003 to 2020 at a single institution. Bilateral orbital volume measurements were taken from the initial postoperative MRI scan and again at 1- and 5-years postenucleation. The main outcome measure was the longitudinal change in volume difference (∆𝑉). The implant size, age at enucleation, and sex were also evaluated. A linear mixed-effect model was used for analysis. RESULTS: A total of 124 patients (73 males) with HA implants following enucleation were included. Overall, the unaffected orbit trended toward having a greater volume compared with the enucleated orbit, but this was not statistically significant (ß = 0.003; p = 0.122). The mean age at enucleation was 2.4 years. The median time between enucleation and the initial, 1-year, and 5-year postoperative MRIs was 6 months, 17 months, and 55 months, respectively. There was no statistical correlation between age at enucleation, gender, implant size, or orbital volume at any time points (p > 0.05). CONCLUSIONS: Patients treated with enucleation and primary HA implant placement for unilateral retinoblastoma did not display significant asymmetry in orbital volume on 5-year postenucleation MRIs, suggesting that HA implants promote orbital growth comparable to a nonenucleated orbit in the pediatric population.

An unusual case of a pigment epithelial cyst masquerading as a uveal melanoma after zoster ophthalmicus-related iris atrophy.

Purpose: To report the case of a 69-year-old male who was referred for a previously unidentified pigmented iris lesion with surrounding iris atrophy masquerading as an iris melanoma. Observations: A sharply demarcated pigmented lesion extending from the trabecular meshwork to the pupillary margin was identified in the left eye. There was adjacent iris stromal atrophy. Testing was consistent with a cyst-like lesion. The patient later described a prior episode of ipsilateral herpes zoster involving the ophthalmic division of cranial nerve five. Conclusions and Importance: Iris cysts present an uncommon iris tumor, often going unrecognized especially if located on the posterior iris surface. When they present acutely, as in this case where a previously unidentified cyst was revealed following zoster-induced sectoral iris atrophy, these pigmented lesions can be concerning for malignancy. Accurately identifying iris melanomas and differentiating them from benign iris lesions is imperative.

Actin filaments partition primary cilia membranes into distinct fluid corrals.

Physical properties of primary cilia membranes in living cells were examined using two independent, high-spatiotemporal-resolution approaches: fast tracking of single quantum dot-labeled G protein-coupled receptors and a novel two-photon super-resolution fluorescence recovery after photobleaching of protein ensemble. Both approaches demonstrated the cilium membrane to be partitioned into corralled domains spanning 274 ± 20 nm, within which the receptors are transiently confined for 0.71 ± 0.09 s. The mean membrane diffusion coefficient within the corrals, Dm1 = 2.9 ± 0.41 µm2/s, showed that the ciliary membranes were among the most fluid encountered. At longer times, the apparent membrane diffusion coefficient, Dm2 = 0.23 ± 0.05 µm2/s, showed that corral boundaries impeded receptor diffusion 13-fold. Mathematical simulations predict the probability of G protein-coupled receptors crossing corral boundaries to be 1 in 472. Remarkably, latrunculin A, cytochalasin D, and jasplakinolide treatments altered the corral permeability. Ciliary membranes are thus partitioned into highly fluid membrane nanodomains that are delimited by filamentous actin.