The Effects of Hyperbaric Oxygen Therapy in Patients with Central Retinal Artery Occlusion: A Retrospective Study, Systematic Review, and Meta-analysis.

PURPOSE: Central retinal artery occlusion (CRAO) is a vision-threatening condition with a potentially poor visual prognosis. Many different treatment modalities are suggested but controversy remains regarding effectiveness of these treatments. The purpose of this study is to perform a systematic review and meta-analysis in addition to analyzing retrospective data at our own tertiary care center regarding effectiveness of hyperbaric oxygen therapy (HBOT) in treatment of CRAO. METHODS: The PubMed, Scopus, and the Cochrane Library are searched from the date of database inception to September 2021 to conduct a review based on the PRISMA (preferred reporting items for systematic review and meta-analysis), evaluating the role of HBOT in visual recovery of CRAO patients. In addition, a retrospective chart review of patients clinically diagnosed with CRAO at our university-based hospital (University of Texas Health, San Antonio, TX, USA) from year 2011 to 2021 was conducted. RESULTS: After a review of 376 articles, three articles met the inclusion criteria for meta-analysis, where a total of 207 patients received HBOT versus 89 patients that did not receive any form of oxygen therapy. Analysis of these results demonstrate that HBOT in CRAO patients does not enhance the final visual outcome (p = 0.83). Similar conclusion was also drawn from retrospective analysis of 48 patients (15 HBOT versus 33 controls) at our tertiary care center, where no visual benefit was observed in the HBOT group. CONCLUSIONS: HBOT does not appear to improve final visual outcome and concerns remain regarding adverse reactions such as barotrauma and generalized seizures. Large, randomized studies are required for further understanding of the role of HBOT in treatment of CRAO.

Protective Role of 360° Laser Retinopexy in Patients with Rhegmatogenous Retinal Detachment: a Systematic Review and Meta-analysis.

PURPOSE: Visual impairment from retinal re-detachment could be debilitating. The aim of this review is to evaluate the role of 360° laser retinopexy on success rate of rhegmatogenous retinal detachment (RRD) repair by a meta-analysis study. METHODS: The PubMed, Scopus, and the Cochrane Library databases were searched comprehensively from the date of database inception to January 2021, evaluating the role of 360° laser retinopexy in visual and anatomical success rate of RRD repair. This review was conducted based on the preferred reporting items for systematic review and meta-analysis (PRISMA) protocols. RESULTS: Among 202 articles screened for eligibility, six studies were found to be eligible for inclusion in our final analysis. Our meta-analysis demonstrates that prophylactic treatment with circumferential laser photocoagulation has no significant effect on the initial rate of retinal re-detachment or final best-corrected visual acuity following pars plana vitrectomy repair of RRD. Subgroup analysis of studies (n = 3) with 23-gauge pars plana vitrectomy, however, favors attachment rate in patients undergoing 360° prophylactic laser treatment. CONCLUSIONS: Three hundred and sixty degree laser retinopexy appears to have favorable outcomes in patients undergoing 23-gauge retinal detachment repair. This protective effect, however, is not apparent with inclusion of 20-gauge vitrectomy studies.

The effects of temporary intraocular pressure spikes after intravitreal dexamethasone implantation on the retinal nerve fiber layer.

Background and objective: The dexamethasone (DEX) implant is known to cause temporary intraocular pressure (IOP) spikes after implantation. The purpose of this study is to determine if IOP spikes after DEX implant cause significant thinning in the retinal nerve fiber layer (RNFL). Study design, patients, and methods: A total of 306 charts were reviewed with 48 and 21 patients meeting inclusion criteria for the cross-sectional and prospective groups, respectively. Cross-sectional inclusion criteria: IOP spike ≥22 mmHg up to 16 weeks after DEX implant, DEX implant in only 1 eye per patient, and spectral-domain optical coherence tomography (OCT) RNFL imaging of both eyes ≥3 months after IOP spike. Prospective inclusion criteria: OCT RNFL performed within 1 year prior to DEX implantation, IOP spike ≥22 mmHg up to 16 weeks after DEX implant, and OCT RNFL performed ≥3 months after IOP spike. The average RNFL thickness in the contralateral eye was used as the control in the cross-sectional group. Institutional review board approval was obtained. Results: In the cross-sectional group, there was no statistically significant difference in the mean RNFL thicknesses in the treated vs untreated eyes (80.4±15.5 µm and 82.6±15.8 µm, respectively; P=0.33) regardless of treatment diagnosis, magnitude of IOP spike, or history of glaucoma. In the prospective group, mean RNFL thicknesses before and after IOP spikes ≥22 mmHg were similar (78.0±14.8 µm and 75.6±13.6 µm, respectively; P=0.13). Conclusion and relevance: Temporary elevation of IOP after DEX implantation when treated with topical IOP lowering drops does not appear to lead to a meaningful change in RNFL thickness.

Natural History of Conversion of Leber's Hereditary Optic Neuropathy: A Prospective Case Series.

PURPOSE: To illustrate the natural history of Leber's hereditary optic neuropathy (LHON). DESIGN: Prospective observational case series. PARTICIPANTS: The Soave-Brazil pedigree of m.11778G>A/ND4 mitochondrial DNA LHON mutation. METHODS: A prospectively acquired database of the Soave-Brazil pedigree was reviewed. Data from 285 individuals were included in the database over a 15-year period. The pedigree was reviewed for unaffected mutation carriers who converted to affected status, 6 patients with LHON were identified. The medical records were reviewed 1 year preconversion to 1 year postconversion for visual acuity (logarithm of the minimum angle of resolution [logMAR]), Humphrey Visual Field (HVF) mean deviation (MD), and retinal nerve fiber layer (RNFL) thickness, as measured by Cirrus (Carl Zeiss, Oberkochen, Germany) optic coherence tomography (OCT). The RNFL thickness values were normalized for age. Visual acuity, HVF, and processed RNFL data from each of the 12 eyes were then sorted into 2-month time periods relative to the date of conversion, within which they were averaged. MAIN OUTCOME MEASURES: The main outcome measures were visual acuity, HVF MD, and RNFL thickness. RESULTS: Decreased visual acuity preceded conversion by up to 2 months and then declined up to 8 months postconversion. Decrease in HVF MD occurred at least 4 months preceding conversion, after which values decreased until plateau at 6 to 8 months. Average RNFL thickness was above normal baseline thickness in all 4 quadrants as measured by OCT at the time of conversion. Increase in RNFL thickness preceded conversion as early as 4 to 6 months, peaked at conversion, and decreased until individual plateaus. The temporal quadrant was first to be involved, then the inferior and superior quadrants, and the nasal quadrant showed the latest and least changes. CONCLUSIONS: Subclinical changes preceded the date of conversion and may reflect the complicated nature of identifying the date of conversion in LHON. Early increases in RNFL preceding conversion suggest that structural changes precede clinically significant vision loss. Asynchronous quadrant involvement supports a previously published mathematical model. The natural history of LHON is not a subacute process, as previously believed, but progresses more slowly, taking up to 8 months to plateau.

Total Outflow Facility in Live C57BL/6 Mice of Different Age.

PURPOSE: To characterize total outflow facility across the live adult mouse lifespan as a reference for mouse glaucoma studies and the common C57BL/6 background strain. METHODS: Microperfusion was performed by single-needle cannulation and feedback-controlled coupling of pressure and flow to maintain a constant pressure in the anterior chambers of live C57BL/6NCrl mice aged 3-4 months (n = 17), 6-9 months (n = 10), and 23-27 months (n = 12). This mouse age range represented an equivalent human age range of young adult to elderly. We characterized the following across age groups in vivo: (1) outflow facility based on constant pressure perfusion in a pressure range of 15-35 mm Hg, (2) perfusion flow rates, and (3) anterior segment tissue histology after perfusion. Thirty-nine live mice underwent perfusion. RESULTS: Pressure-flow rate functions were consistently linear for all age groups (all R 2 > 0.96). Total outflow facility in mice aged 3-4, 6-9, and 23-27 months was 0.0066, 0.0064, and 0.0077 µL/min/mm Hg, respectively. Facility was not significantly different between age groups (all p > 0.4). The groups had closely overlapping frequency distribution profiles with right-sided tails. Post hoc estimates indicated that group facility differences of at least 50% would have been detectable, with this limit set mainly by inherent variability in the strain. A trend toward higher perfusion flow rates was seen in older mice aged 23-27 months, but this was not significantly different from that of mice aged 3-4 months or 6-9 months (p > 0.2). No histological disruption or difference in iridocorneal angle or drainage tissue structure was seen following perfusion in the different age groups. CONCLUSION: We did not find a significant difference in total outflow facility between different age groups across the live C57BL/6 mouse adult lifespan, agreeing with some human studies. The possibility that more subtle differences might exist ought to be judged with respect to the heterogeneity in facility at different ages. Our findings provide reference data for live perfusion studies pertaining to glaucoma involving the C57BL/6 strain.

Correcting Finger Counting to Snellen Acuity.

In this paper, the authors describe an online tool with which to convert and thus quantify count finger measurements of visual acuity into Snellen equivalents. It is hoped that this tool allows for the re-interpretation of retrospectively collected data that provide visual acuity in terms of qualitative count finger measurements.

Tissue-based imaging model of human trabecular meshwork.

We have developed a tissue-based model of the human trabecular meshwork (TM) using viable postmortem corneoscleral donor tissue. Two-photon microscopy is used to optically section and image deep in the tissue to analyze cells and extracellular matrix (ECM) within the original three-dimensional (3D) environment of the TM. Multimodal techniques, including autofluorescence (AF), second harmonic generation (SHG), intravital dye fluorescence, and epifluorescence, are combined to provide unique views of the tissue at the cellular and subcellular level. SHG and AF imaging are non-invasive tissue imaging techniques with potential for clinical application, which can be modeled in the system. We describe the following in the tissue-based model: analysis of live cellularity to determine tissue viability; characteristics of live cells based on intravital labeling; features and composition of the TM's structural ECM; localization of specific ECM proteins to regions such as basement membrane; in situ induction and expression of tissue markers characteristic of cultured TM cells relevant to glaucoma; analysis of TM actin and pharmacological effects; in situ visualization of TM, inner wall endothelium, and Schlemm's canal; and application of 3D reconstruction, modeling, and quantitative analysis to the TM. The human model represents a cost-effective use of valuable and scarce yet available human tissue that allows unique cell biology, pharmacology, and translational studies of the TM.

Concurrent central retinal artery occlusion and branch retinal vein occlusion in giant cell arteritis.

Ophthalmic involvement in giant cell arteritis can manifest in a number of ways. Central retinal artery occlusion is one of the common causes of visual loss in giant cell arteritis. On the contrary, branch retinal vein occlusion is rarely associated with the latter. We report an 89-year-old lady with acute left central retinal artery occlusion on a background of progressive decline in vision over a 6-month period with a concurrent right branch retinal vein occlusion. Subsequent investigation confirmed giant cell arteritis on temporal artery biopsy. This is the first reported case of a concurrent central retinal artery occlusion and branch retinal vein occlusion in giant cell arteritis, and highlights the various ocular presentations that can occur in giant cell arteritis.

Venom ophthalmia caused by venoms of spitting elapid and other snakes: Report of ten cases with review of epidemiology, clinical features, pathophysiology and management.

Venom ophthalmia caused by venoms of spitting elapid and other snakes: report of ten cases with review of epidemiology, clinical features, pathophysiology and management. Chu, ER, Weinstein, SA, White, J and Warrell, DA. Toxicon XX:xxx-xxx. We present ten cases of ocular injury following instillation into the eye of snake venoms or toxins by spitting elapids and other snakes. The natural history of spitting elapids and the toxinology of their venoms are reviewed together with the medical effects and management of venom ophthalmia in humans and domestic animals including both direct and allergic effects of venoms. Although the clinical features and management of envenoming following bites by spitting elapids (genera Naja and Hemachatus) are well documented, these snakes are also capable of "spraying" venom towards the eyes of predators, a defensive strategy that causes painful and potentially blinding ocular envenoming (venom ophthalmia). Little attention has been given to the detailed clinical description, clinical evolution and efficacy of treatment of venom ophthalmia and no clear management guidelines have been formulated. Knowledge of the pathophysiology of ocular envenoming is based largely on animal studies and a limited body of clinical information. A few cases of ocular exposure to venoms from crotaline viperids have also been described. Venom ophthalmia often presents with pain, hyperemia, blepharitis, blepharospasm and corneal erosions. Delay or lack of treatment may result in corneal opacity, hypopyon and/or blindness. When venom is "spat" into the eye, cranial nerve VII may be affected by local spread of venom but systemic envenoming has not been documented in human patients. Management of venom ophthalmia consists of: 1) urgent decontamination by copious irrigation 2) analgesia by vasoconstrictors with weak mydriatic activity (e.g. epinephrine) and limited topical administration of local anesthetics (e.g. tetracaine) 3) exclusion of corneal abrasions by fluorescein staining with a slit lamp examination and application of prophylactic topical antibiotics 4) prevention of posterior synechiae, ciliary spasm and discomfort with topical cycloplegics and 5) antihistamines in case of allergic kerato-conjunctivitis. Topical or intravenous antivenom and topical corticosteroids are contraindicated. Clinical outcome of venom ophthalmia is largely dependent on prompt treatment and appropriate follow-up.

Optic neuritis--more than a loss of vision.

BACKGROUND: Optic neuritis is an acute inflammation of the optic nerve that results in painful loss of vision. Patients often present to a general practitioner, and early recognition is important as treatment may improve the speed of vision recovery. OBJECTIVE: This article provides information on the signs and symptoms of optic neuritis and discusses appropriate referral, investigations and management. DISCUSSION: Optic neuritis is the presenting symptom in up to one-fifth of people with multiple sclerosis. Diagnosis of optic neuritis is based on history and examination, therefore obtaining pertinent information and performing proper ophthalmic examination is essential. Prompt recognition and appropriate referral is important to facilitate investigations such as magnetic resonance imaging of the brain that can help predict risk in the development of multiple sclerosis.