Randomized Controlled Study of Cooled vs Room-Temperature Artificial Tears for Reducing Ocular Surface Irritation After Intravitreal Injection.

Purpose: To evaluate the efficacy of cooled vs room-temperature artificial tears in reducing ocular discomfort after intravitreal injections (IVIs). Methods: Patients receiving a standard intravitreal injection in the retina clinic who met the eligibility criteria and provided informed consented were enrolled in the study. Patients were randomized to the cooled tears or room-temperature tears intervention group. Both groups rated their ocular discomfort following IVI after cooled or room-temperature tears were administered. Results: The cooled group comprised 48 patients and the room-temperature group, 61 patients. There was no significant difference in the reduction of ocular discomfort between the cooled vs room-temperature artificial tears groups (P = .387). In addition, there was a similar level of reduction in ocular discomfort after either intervention (P = .681) regardless of whether or not the patients routinely used artificial tears after previous IVIs. Conclusions: Cooled tears provided no additional benefit in reducing ocular discomfort post-IVI compared with room-temperature tears. Baseline tear use after an IVI may have no true benefit other than a potential placebo effect, recall bias, or both.

Metabolic and proteomic indications of diabetes progression in human aqueous humor.

Diabetes mellitus is a multiorgan systemic disease impacting numerous ocular structures that results in significant ocular morbidity and often results in more frequent corneal and glaucoma surgeries for affected individuals. We hypothesize that the systemic metabolic and proteomic derangement observed in the progression of diabetes influences the composition of the aqueous humor (AH), which ultimately impacts the anterior segment health of the eye. To identify changes associated with diabetes progression, we mapped the metabolite profile and proteome of AH samples from patients with varying severities of type II diabetes (T2DM). Patients were classified as nondiabetic (ND or control), non-insulin-dependent diabetic without advanced features of disease (NAD-ni), insulin-dependent diabetic without advanced features (NAD-i), or diabetic with advanced features (AD). AH samples collected from the anterior chamber during elective ophthalmic surgery were evaluated for metabolite and protein expression changes associated with diabetic severity via gas chromatography/mass spectrometry and ultra-high performance liquid chromatography tandem mass spectrometry, respectively. Metabolic and proteomic pathway analyses were conducted utilizing MetaboAnalyst 4.0 and Ingenuity Pathway Analysis. A total of 14 control, 12 NAD-ni, 4 NAD-I, and 14 AD samples were included for analysis. Elevated levels of several branched amino acids (e.g., valine, leucine, isoleucine), and lipid metabolites (e.g., palmitate) were found only with increasing diabetic severity (i.e., the AD group). Similar proteomic trends were noted in amino acid and fatty acid metabolism and the unfolded protein/stress response. These results represent the first report of both metabolomic and proteomic evaluation of aqueous humor. Diabetes results in metabolic and proteomic perturbations detectable in the AH, and unique changes become manifest as T2DM severity worsens. Changes in AH composition may serve as an indicator of disease severity, risk assessment of anterior segment cells and structures, and potential future therapies.

Modeling rod and cone photoreceptor cell survival in vivo using optical coherence tomography.

Many retinal diseases involve the loss of light-sensing photoreceptor cells (rods and cones) over time. The severity and distribution of photoreceptor loss varies widely across diseases and affected individuals, so characterizing the degree and pattern of photoreceptor loss can clarify pathophysiology and prognosis. Currently, in vivo visualization of individual photoreceptors requires technology such as adaptive optics, which has numerous limitations and is not widely used. By contrast, optical coherence tomography (OCT) is nearly ubiquitous in daily clinical practice given its ease of image acquisition and detailed visualization of retinal structure. However, OCT cannot resolve individual photoreceptors, and no OCT-based method exists to distinguish between the loss of rods versus cones. Here, we present a computational model that quantitatively estimates rod versus cone photoreceptor loss from OCT. Using histologic data of human photoreceptor topography, we constructed an OCT-based reference model to simulate outer nuclear layer thinning caused by differential loss of rods and cones. The model was able to estimate rod and cone loss using in vivo OCT data from patients with Stargardt disease and healthy controls. Our model provides a powerful new tool to quantify photoreceptor loss using OCT data alone, with potentially broad applications for research and clinical care.

Retinal Sublayer Analysis in Autoimmune Retinopathy and Identification of New Optical Coherence Tomography Phenotypes.

PURPOSE: Autoimmune retinopathy (AIR) is a poorly characterized disease with a wide phenotypic spectrum, complicating investigations of its underlying pathophysiology. We sought to analyze optical coherence tomography (OCT) retinal thickness changes in AIR patients. METHODS: A retrospective chart review from 2007 to 2017 was performed evaluating AIR patients at a single academic, tertiary referral center. OCT retinal sublayer analysis was performed, and paradoxical thickening phenotypes were reviewed. RESULTS: Twenty-nine AIR patients with positive anti-retinal antibodies and OCT imaging were identified. Overall, AIR patients had thinner retinal sublayers compared to controls; however, 12 patients (41.4%) had paradoxical thickening of the outer plexiform layer (OPL). This revealed two distinct OCT phenotypes. No association was found between retinal sublayer thickness and specific antiretinal antibodies. CONCLUSIONS: While the pathogenicity of antiretinal antibodies remains unclear, the OCT phenotypes observed underscore the potential for identifying clues in the underlying disease processes and clinical diagnosis.

Risk Factors for Fibrous Ingrowth in Eyes Requiring Primary Keratoplasty.

PURPOSE: The aim of this study was to define risks for corneal transplantation associated with fibrous ingrowth among first-time transplant recipients. METHODS: We performed a retrospective case-control study of patients with a histopathologic diagnosis of fibrous ingrowth between 2002 and 2019. Patients with fibrous ingrowth from a first corneal specimen were included. Those with incomplete records were excluded. A 1:2 case-control ratio was used. Controls were matched using surgical indication, surgery year, transplantation method, sex, and age. RESULTS: Seventy-eight eyes (76 patients) were included and matched with 160 control eyes. The incidence of fibrous ingrowth found on a first corneal transplant was 0.6% per year. The most common keratoplasty indications were pseudophakic corneal edema (n = 25, 32%) and aphakic corneal edema (n = 15, 19%). Cases were more likely to have a history of ocular trauma (odds ratio [OR], 2.94; 95% CI, 1.30-6.30; P = 0.007), uveitis (OR, 2.73; 95% CI, 1.12-6.63; P = 0.022), retinal detachment or previous retinal surgery (OR, 2.40; 95% CI, 1.34-4.30; P = 0.003), glaucoma tube-shunt surgery (OR, 2.70; 95% CI, 1.29-5.65; P = 0.007), aphakia (OR, 3.02; 95% CI, 1.61-5.67; P = 0.0004), or iris derangement (OR, 10.52; 95% CI, 5.45-20.30; P <0.0001). A multivariate logistic regression model using iris derangement, history of ocular trauma, history of uveitis, and history of cataract surgery demonstrated 81% sensitivity and 66% specificity in predicting presence of fibrous ingrowth. CONCLUSIONS: A history of ocular trauma, uveitis, retinal detachment or previous retinal surgery, glaucoma tube-shunt surgery, aphakia, and iris derangement are risks for detecting fibrous ingrowth among first-time keratoplasty recipients. Patients with these conditions should be monitored closely for corneal decompensation.

In Vivo Imaging of Retinal and Choroidal Morphology and Vascular Plexuses of Vertebrates Using Swept-Source Optical Coherence Tomography.

Purpose: To perform in vivo evaluation of the structural morphology and vascular plexuses of the neurosensory retina and choroid across vertebrate species using swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA) imaging. Methods: A custom-built SS-OCT system with an incorporated flexible imaging arm was used to acquire the three-dimensional (3D) retinal OCT and vascular OCTA data of five different vertebrates: a mouse (C57BL/6J), a rat (Long Evans), a gray short-tailed opossum (Monodelphis domestica), a white sturgeon (Acipenser transmontanus), and a great horned owl (Bubo virginianus). Results: In vivo structural morphology of the retina and choroid, as well as en face OCTA images of retinal and choroidal vasculature of all species were generated. The retinal morphology and vascular plexuses were similar between rat and mouse, whereas distinct choroidal and paired superficial vessels were observed in the opossum retina. The retinal and vascular structure of the sturgeon, as well as the pecten oculi and overlying the avascular and choroidal vasculature in the owl retina are reported in vivo. Conclusions: A high-quality two-dimensional and 3D in vivo visualization of the retinal structures and en face visualization of the retina and choroidal vascular plexus of vertebrates was possible. Our studies affirm that SS-OCT and SS-OCTA are viable methods for evaluating the in vivo retinal and choroidal structure across terrestrial, aquatic, and aerial vertebrates. Translational Relevance: In vivo characterization of retinal morphology and vasculature plexus of multiple species using SS-OCT and SS-OCTA imaging can increase the pool of species available as models of human retinal diseases.

Guinea pig sensitization assays: an experimental comparison of three methods.

PURPOSE: Guinea pig sensitization assays provide a critical tool in toxicological testing. Here, we investigate the relative sensitivities of the Guinea Pig Maximization Test (GPMT), the Open Epicutaneous Test (OET), and the Buehler test on seven common compounds. METHODS: Seven compounds (formalin, nickel sulfate, 2-benzothiazolethiol, neomycin sulfate, potassium dichromate, ethylenediamine, dihydrochloride, and cinnamyl alcohol) were investigated on 15 guinea pigs per assay. Differences between each assay were investigated individually for each compound in question, and cumulative comparisons were also performed. RESULTS: Cumulatively, differences in rates of sensitization between the GPMT and OET did not reach statistical significance; however, both tests produced higher sensitization rates than the Buehler test (1% significance level). Comparisons for individual compounds are outlined within the main text. CONCLUSIONS: Our results indicate a possible role for the OET in the testing of weakly allergenic compounds. Similarly, the Buehler test may hold greatest utility in the examination of strongly allergenic compounds, where high sensitivity is not necessary and limited exposure to subjects is desired. These findings may help guide experimental protocols and considerations.

Correlation of features on OCT with visual acuity and Gass lesion type in Best vitelliform macular dystrophy.

OBJECTIVE: To correlate structural features seen on optical coherence tomography (OCT) with best-corrected visual acuity (BCVA) and Gass lesion type in patients with Best vitelliform macular dystrophy (BVMD). METHODS AND ANALYSIS: This is a retrospective case series of consecutive patients with molecularly confirmed BEST1-associated BVMD. OCT scans were reviewed for lesion status and presence of subretinal pillar, focal choroidal excavation (FCE), intraretinal fluid or atrophy. Available OCT angiography images were used to evaluate for the presence of choroidal neovascularisation (CNV). These features were then correlated with BCVA and Gass lesion type. RESULTS: 95 eyes from 48 patients (mean age 38.9 years, range 4-87) were included. The presence of a pillar (24.2%), FCE (20.0%) and atrophy (7.4%) were associated with poor BCVA (p<0.05). Gass lesion type 1 eyes were correlated with good BCVA (LogMAR <0.4) whereas type 5 eyes had poor BCVA (LogMAR >0.4). Among 65 eyes with longitudinal data (mean follow-up 5.1 years), 7 eyes (10.8%) reverted from higher to lower Gass lesion type; of these, 4 eyes (57.1%) had CNV responsive to intravitreal anti-vascular endothelial growth factor treatment. CONCLUSION: OCT-based structural features are readily identifiable in patients with BVMD and have prognostic importance due to their correlation with BCVA.

Preserving Vision: Rethinking Burn Patient Monitoring to Prevent Orbital Compartment Syndrome.

Burn patients receiving aggressive fluid resuscitation are at risk of developing orbital compartment syndrome (OCS). This condition results in elevated orbital pressures and can lead to rapid permanent vision loss. Risk factors and monitoring frequency for OCS remain largely unknown. A retrospective review was therefore conducted of admitted burn patients evaluated by the ophthalmology service at an American Burn Association verified Burn Treatment Center. Demographic, burn, examination, and fluid resuscitation data were compared using two-sided t-tests, Fisher's exact tests, and linear regression. Risk factors for elevated intraocular pressures (IOPs; a surrogate for intraorbital pressure) in patients resuscitated via the Parkland formula were found to be total body surface area (% TBSA) burned, resuscitation above the Ivy Index (>250 ml/kg), and Parkland formula calculated volume. Maximum IOP and actual fluid resuscitation volume were linearly related. Analysis of all patients with elevated IOP found multiple patients with significant IOP increases after initial evaluation resulting in OCS within the first 24 hours postinjury. While %TBSA, Ivy Index, and resuscitation calculated volume are OCS risk factors in burn patients, two patients with facial burns developed OCS (25% of all patients with OCS) despite not requiring resuscitation. Orbital congestion can develop within the first 24 hours of admission when resuscitation volumes are the greatest. In addition to earlier and more frequent IOP checks in susceptible burn patients during the first day, the associated risk factors will help identify those most at risk for OCS and vision loss.

Analysis of retinal sublayer thicknesses and rates of change in ABCA4-associated Stargardt disease.

Stargardt disease, the most common inherited macular dystrophy, is characterized by vision loss due to central retinal atrophy. Although clinical trials for Stargardt are currently underway, the disease is typically slowly progressive, and objective, imaging-based biomarkers are critically needed. In this retrospective, observational study, we characterize the thicknesses of individual retinal sublayers by macular optical coherence tomography (OCT) in a large cohort of patients with molecularly-confirmed, ABCA4-associated Stargardt disease (STGD1) relative to normal controls. Automated segmentation of retinal sublayers was performed with manual correction as needed, and thicknesses in various macular regions were compared using mixed effects models. Relative to controls (42 eyes, 40 patients), STGD1 patients (107 eyes, 63 patients) had slight thickening of the nerve fiber layer and retinal pigment epithelium-Bruch's membrane, with thinning in other sublayers, especially the outer nuclear layer (ONL) (p < 0.0015). When comparing the rate of retinal sublayer thickness change over time (mean follow-up 3.9 years for STGD1, 2.5 years for controls), STGD1 retinas thinned faster than controls in the outer retina (ONL to photoreceptor outer segments). OCT-based retinal sublayer thickness measurements are feasible in STGD1 patients and may provide objective measures of disease progression or treatment response.

Speeding rod recovery improves temporal resolution in the retina.

The temporal resolution of the visual system progressively increases with light intensity. Under scotopic conditions, temporal resolution is relatively poor, and may be limited by both retinal and cortical processes. Rod photoresponses themselves are quite slow because of the slowly deactivating biochemical cascade needed for light transduction. Here, we have used a transgenic mouse line with faster than normal rod phototransduction deactivation (RGS9-overexpressors) to test whether rod signaling to second-order retinal neurons is rate-limited by phototransduction or by other mechanisms. We compared electrical responses of individual wild-type and RGS9-overexpressing (RGS9-ox) rods to steady illumination and found that RGS9-ox rods required 2-fold brighter light for comparable activation, owing to faster G-protein deactivation. When presented with flickering stimuli, RGS9-ox rods showed greater magnitude fluctuations around a given steady-state current amplitude. Likewise, in vivo electroretinography (ERG) and whole-cell recording from OFF-bipolar, rod bipolar, and horizontal cells of RGS9-ox mice displayed larger than normal magnitude flicker responses, demonstrating an improved ability to transmit frequency information across the rod synapse. Slow phototransduction recovery therefore limits synaptic transmission of increments and decrements of light intensity across the first retinal synapse in normal retinas, apparently sacrificing temporal responsiveness for greater overall sensitivity in ambient light.