Alasil T, Wang K, Keane PA, Lee H, Baniasadi N, de Boer JF, Chen TC. Analysis of normal retinal nerve fiber layer thickness by age, sex, and race using spectral domain optical coherence tomography. J Glaucoma 2013;22(7):532-41.Abstract
PURPOSE: To determine the effects of age, sex, and race on the retinal nerve fiber layer (RNFL) in the normal human eye as measured by the spectral domain optical coherence tomography (SD-OCT) Spectralis machine (Heidelberg Engineering). METHODS: Peripapillary SD-OCT RNFL thickness measurements were determined in normal subjects seen at a university-based clinic. One randomly selected eye per subject was used for analysis in this cross-sectional study. Multiple regression analysis was applied to assess the effects of age, sex, ethnicity, and mean refractive error on peripapillary RNFL thickness. Results are expressed as means±SD wherever applicable. RESULTS: The study population consisted of 190 healthy participants from 9 to 86 years of age. Of the 190 participants, 62 (33%) were men, 125 (66%) Caucasians, 26 (14%) African Americans, 14 (7%) Hispanics, 16 (8%) Asians, and 9 (5%) other races. The mean RNFL thickness for the normal population studied was 97.3 ± 9.6 µm. Normal RNFL thickness values follow the ISNT rule with decreasing RNFL thickness values starting from the thickest quadrant inferiorly to the thinnest quadrant temporally: inferior quadrant (126 ± 15.8), superior quadrant (117.2±16.13), nasal quadrant (75 ± 13.9), and temporal quadrant (70.6 ± 10.8 µm). Thinner RNFL measurements were associated with older age (P<0.001); being Caucasian, versus being either Hispanic or Asian (P=0.02 and 0.009, respectively); or being more myopic (P<0.001). For every decade of increased age, mean RNFL thickness measured thinner by approximately 1.5 µm (95% confidence interval, 0.24-0.07). Comparisons between ethnic groups revealed that Caucasians had mean RNFL values (96 ± 9.2 µm) slightly thinner than those of Hispanics (102.9 ± 11 µm; P=0.02) or Asians (100.7 ± 8.5 µm; P=0.009). African Americans RNFL values (99.2 ± 10.2 µm) were not significantly different when compared with Caucasians. There was no relationship between RNFL thickness and sex. CONCLUSIONS: The thickest RNFL measurements were found in the inferior quadrant, followed by the superior, nasal, and temporal quadrants (ISNT rule applied to the RNFL). Thinner RNFL measurements were associated with older age and increasing myopia. Caucasians tend to have thinner RNFL values when compared with Hispanics and Asians. SD-OCT analysis of the normal RNFL showed results similar to time domain OCT studies.
Dorr M, Lesmes LA, Lu Z-L, Bex PJ. Rapid and reliable assessment of the contrast sensitivity function on an iPad. Invest Ophthalmol Vis Sci 2013;54(12):7266-73.Abstract
PURPOSE: Letter acuity, the predominant clinical assessment of vision, is relatively insensitive to slow vision loss caused by eye disease. While the contrast sensitivity function (CSF) has demonstrated the potential to monitor the slow progress of blinding eye diseases, current tests of CSF lack the reliability or ease-of-use to capture changes in vision timely. To improve the current state of home testing for vision, we have developed and validated a computerized adaptive test on a commercial tablet device (iPad) that provides an efficient and easy-to-use assessment of the CSF. METHODS: We evaluated the reliability, accuracy, and flexibility of tablet-based CSF assessment. Repeated tablet-based assessments of the spatial CSF, obtained from four normally-sighted observers, which each took 3 to 5 minutes, were compared to measures obtained on CRT-based laboratory equipment; additional tablet-based measures were obtained from six subjects under three different luminance conditions. RESULTS: A Bland-Altman analysis demonstrated that tablet-based assessment was reliable for estimating sensitivities at specific spatial frequencies (coefficient of repeatability 0.14-0.40 log units). The CRT- and tablet-based results demonstrated excellent agreement with absolute mean sensitivity differences <0.05 log units. The tablet-based test also reliably identified changes in contrast sensitivity due to different luminance conditions. CONCLUSIONS: We demonstrate that CSF assessment on a mobile device is indistinguishable from that obtained with specialized laboratory equipment. We also demonstrate better reliability than tests used currently for clinical trials of ophthalmic therapies, drugs, and devices.
Rahimi Darabad R, Suzuki T, Richards SM, Jensen RV, Jakobiec FA, Zakka FR, Liu S, Sullivan DA. Influence of aromatase absence on the gene expression and histology of the mouse meibomian gland. Invest Ophthalmol Vis Sci 2013;54(2):987-98.Abstract
PURPOSE: We hypothesize that aromatase, an enzyme that controls estrogen biosynthesis, plays a major role in the sex-related differences of the meibomian gland. To begin to test this hypothesis, we examined the influence of aromatase absence, which completely eliminates estrogen production, on glandular gene expression and histology in male and female mice. METHODS: Meibomian glands were obtained from adult, age-matched wild-type (WT) and aromatase knockout (ArKO) mice. Tissues were processed for histology or the isolation of total RNA, which was analyzed for differentially expressed mRNAs by using microarrays. RESULTS: Our results show that aromatase significantly influences the expression of more than a thousand genes in the meibomian gland. The nature of this effect is primarily sex-dependent. In addition, the influence of aromatase on sex-related differences in gene expression is predominantly genotype-specific. However, many of the sex-related variations in biological process, molecular function, and cellular component ontologies, as well as in KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, are remarkably similar between WT and ArKO mice. The loss of aromatase activity has no obvious effect on the histology of meibomian glands in male or female mice. CONCLUSIONS: Our findings demonstrate that aromatase has a significant impact on gene expression in the meibomian gland. The nature of this influence is sex-dependent and genotype-specific; however, many of the sex-related variations in gene ontologies and KEGG pathways are similar between WT and ArKO mice. Consequently, it appears that aromatase, and by extension estrogen, do not play a major role in the sex-related differences of the mouse meibomian gland.
Cruzat A, Shukla A, Dohlman CH, Colby K. Wound anatomy after type 1 Boston KPro using oversized back plates. Cornea 2013;32(12):1531-6.Abstract
PURPOSE: To compare the anatomy of the graft-host junction and anterior chamber angle after Boston Keratoprosthesis (KPro) placement using oversized (9.5-mm) and standard (8.5-mm) back plates. METHODS: Six patients with 9.5-mm titanium back plates and 10 patients with 8.5-mm titanium back plates were imaged by anterior segment optical coherence tomography 6 to 12 months after KPro placement. The location of the graft-host junction in relation to the back plate, the corneal thickness at the graft-host junction, and the anterior chamber angle were assessed. The clinical outcomes and incidence of retroprosthetic membrane (RPM) formation in this cohort were retrospectively evaluated. RESULTS: The oversized back plates completely covered the graft-host junction in all quadrants, allowing the complete apposition of the posterior surface of the carrier graft with the host cornea, with decreased graft-host junction wound thickness. The standard back plates covered the posterior aspect of the carrier graft but not the graft-host junction or the host cornea, resulting in a significantly thicker graft-host junction. None of the patients with larger back plates developed a significant RPM during a 12-month follow-up period. One patient with a larger back plate developed a corneal melt at the KPro stem as a result of chronic exposure. CONCLUSIONS: Oversized KPro back plates effectively cover the graft-host junction without any adverse effects on angle anatomy or wound healing. This may be a strategy to provide better wound apposition, reduce RPM formation, and reduce angle closure from iris synechiae to the wound.
Chen Y, Chauhan SK, Lee HS, Stevenson W, Schaumburg CS, Sadrai Z, Saban DR, Kodati S, Stern ME, Dana R. Effect of desiccating environmental stress versus systemic muscarinic AChR blockade on dry eye immunopathogenesis. Invest Ophthalmol Vis Sci 2013;54(4):2457-64.Abstract
PURPOSE: A majority of experimental data on dry eye disease (DED) immunopathogenesis have been derived from a murine model of DED that combines desiccating environmental stress with systemic muscarinic acetylcholine receptor (mAChR) inhibition. However, to our knowledge the effects of pharmacologic mAChR blockade on the pathogenesis of experimental DED have not been evaluated systemically. The purpose of our study was to investigate the differential effects of desiccating environmental stress and mAChR inhibition on the pathogenesis of DED. METHODS: DED was induced in female C57BL/6 mice by exposure to a desiccating environment in the controlled-environment chamber or to systemic scopolamine, or by performing extraorbital lacrimal gland excision. Clinical disease was assessed using corneal fluorescein staining (CFS) and the cotton thread test (CTT). Corneal CD11b(+) and conjunctival CD3(+) T-cell infiltration were evaluated by flow cytometry. T-cells from draining cervical lymph nodes (CLN) and distant inguinal lymph nodes (ILN) were analyzed for Th1, Th2, Th17, and Treg responses by flow cytometry and ELISA. RESULTS: Desiccating environmental stress and systemic mAChR blockade induced similar clinical signs of DED. However, desiccating environmental stress imparted higher conjunctival CD3(+) T-cell infiltration, and greater Th17-cell activity and Treg dysfunction than mAChR blockade, while mAChR blockade decreased tear secretion to a greater extent than desiccating environmental stress. Systemic mAChR blockade attenuated Th17 activity and enhanced Th2 and Treg responses without affecting Th1 activity. CONCLUSIONS: In vivo inhibition of mAChRs variably affects CD4(+) T-cell subsets, and desiccating environmental stress and systemic mAChR blockade induce DED through different primary pathogenic mechanisms.
Bressler SB, Almukhtar T, Aiello LP, Bressler NM, Ferris FL, Glassman AR, Greven CM, Greven CM. Green or yellow laser treatment for diabetic macular edema: exploratory assessment within the Diabetic Retinopathy Clinical Research Network. Retina 2013;33(10):2080-8.Abstract
PURPOSE: Explore differences in green compared with yellow focal/grid laser treatment on functional and anatomical endpoints in eyes with diabetic macular edema. METHODS: Data from two randomized clinical trials were evaluated for differences in visual acuity and optical coherence tomography parameters for eyes assigned to sham injection + prompt laser, ranibizumab + prompt laser, or prompt laser only: among subgroups of eyes treated exclusively and electively with either green or yellow laser. RESULTS: In the sham injection + prompt laser group, the mean visual acuity letter score change for eyes receiving green and yellow laser treatment, respectively, was +2.4 ± 14 and +5.1 ± 13 at the 52-week visit (P = 0.06) and +2.4 ± 15 and +6.0 ± 13 at the 104-week visit (P = 0.13), with no corresponding evidence of differences in optical coherence tomography thickness. When comparing wavelength groups in the ranibizumab + prompt laser and prompt laser-only groups, meaningful differences in visual acuity and optical coherence tomography thickness were not detected at 1 year or 2 years. CONCLUSION: A trend toward improved vision outcome with yellow laser observed in one trial was not corroborated by anatomical outcomes or by the other trial. In this study, without random assignment to different wavelengths controlling for bias and confounding, it is not possible to determine whether one wavelength is better than the other.
Beier KT, Saunders AB, Oldenburg IA, Sabatini BL, Cepko CL. Vesicular stomatitis virus with the rabies virus glycoprotein directs retrograde transsynaptic transport among neurons in vivo. Front Neural Circuits 2013;7:11.Abstract
Defining the connections among neurons is critical to our understanding of the structure and function of the nervous system. Recombinant viruses engineered to transmit across synapses provide a powerful approach for the dissection of neuronal circuitry in vivo. We recently demonstrated that recombinant vesicular stomatitis virus (VSV) can be endowed with anterograde or retrograde transsynaptic tracing ability by providing the virus with different glycoproteins. Here we extend the characterization of the transmission and gene expression of recombinant VSV (rVSV) with the rabies virus glycoprotein (RABV-G), and provide examples of its activity relative to the anterograde transsynaptic tracer form of rVSV. rVSV with RABV-G was found to drive strong expression of transgenes and to spread rapidly from neuron to neuron in only a retrograde manner. Depending upon how the RABV-G was delivered, VSV served as a polysynaptic or monosynaptic tracer, or was able to define projections through axonal uptake and retrograde transport. In animals co-infected with rVSV in its anterograde form, rVSV with RABV-G could be used to begin to characterize the similarities and differences in connections to different areas. rVSV with RABV-G provides a flexible, rapid, and versatile tracing tool that complements the previously described VSV-based anterograde transsynaptic tracer.
Feke GT, Rhee DJ, Turalba AV, Pasquale LR. Effects of dorzolamide-timolol and brimonidine-timolol on retinal vascular autoregulation and ocular perfusion pressure in primary open angle glaucoma. J Ocul Pharmacol Ther 2013;29(7):639-45.Abstract
PURPOSE: To assess whether dorzolamide 2%-timolol 0.5% (D/T) and/or brimonidine 0.2%-timolol 0.5% (B/T) alters retinal vascular autoregulation (RVA) and seated ocular perfusion pressure (sOPP) in primary open angle glaucoma (POAG) patients who demonstrate retinal vascular dysregulation (RVD) on timolol 0.5% alone. METHODS: In this prospective, observer-masked, crossover study, 21 POAG patients with untreated intraocular pressure (IOP) >21 mmHg were treated for 6 weeks with timolol 0.5%. Subsequently, we measured inferior temporal retinal artery blood flow in the left eye with subjects seated and then while reclined for 30 min using the Canon Laser Blood Flowmeter. Subjects with a change in retinal blood flow in response to posture change outside of the range previously found in healthy subjects were designated as having RVD and randomized to either D/T or B/T for 6 weeks and re-tested. This was followed by treatment with the opposite medication. RESULTS: Seven of the 21 subjects demonstrated RVD in response to posture change following timolol 0.5%. Multiple linear regression analysis indicated that lower sOPP was the main determinant of RVD (P=0.033). After treatment with D/T, all 7 converted from RVD to normal RVA status (P=0.001). Four of 6 subjects showed a similar return to normal RVA following B/T (P=0.066). Mid-morning sOPP was 41.1±5.5 mmHg post-timolol, 46.3±6.5 mmHg post-D/T, and 38.6±6.0 mmHg post-B/T (D/T vs. B/T, P=0.026). CONCLUSIONS: D/T significantly improved RVA in POAG patients exhibiting RVD while on timolol 0.5% alone. D/T also increased sOPP compared to B/T. There was no significant difference (P=0.37) between D/T and B/T in improving RVA.
Amparo F, Wang H, Emami-Naeini P, Karimian P, Dana R. The Ocular Redness Index: a novel automated method for measuring ocular injection. Invest Ophthalmol Vis Sci 2013;54(7):4821-6.Abstract
PURPOSE: To develop and validate a novel automated system to assess ocular redness (OR) in clinical images. METHODS: We developed a novel software that quantifies OR in digital images based on a mathematic algorithm using a centesimal continuous scoring scale. Subsequently, we conducted a study to validate the scores obtained with this system by correlating them with those obtained by two physicians using two image-based comparative subjective scales, the Efron and the Validated Bulbar Redness (VBR) grading scales. Additionally, we evaluated the level of clinical agreement between the Ocular Redness Index (ORI) score and the two image-based methods by means of the Bland-Altman analysis. Main outcome measures included correlation and level of agreement between the ORI score, Efron score, and the VBR score. RESULTS: One hundred and two clinical photographs of eyes with OR were evaluated. The ORI scores significantly correlated with the scores obtained by the two clinicians using the Efron (Observer 1, R=0.925, P<0.001; Observer 2, R=0.857, P<0.001), and VBR (Observer 1, R=0.830, P<0.001; Observer 2, R=0.821, P<0.001) scales. The Bland-Altman analysis revealed levels of disagreement of up to 30 and 27 units for the ORI-Efron and ORI-VBR score comparisons, respectively. CONCLUSIONS: The ORI provides an objective and continuous scale for evaluating ocular injection in an automated manner, and without need for a trained physician for scoring. The ORI may be used as a new alternative for objective OR evaluation in clinics and in clinical trials.
Ehrenberg M, Pierce EA, Cox GF, Fulton AB. CRB1: one gene, many phenotypes. Semin Ophthalmol 2013;28(5-6):397-405.Abstract
Mutations in the CRB1 gene cause severe retinal degenerations, which may present as Leber congenital amaurosis, early onset retinal dystrophy, retinitis pigmentosa, or cone-rod dystrophy. Some clinical features should alert the ophthalmologist to the possibility of CRB1 disease. These features are nummular pigmentation of the retina, atrophic macula, retinal degeneration associated with Coats disease, and a unique form of retinitis pigmentosa named para-arteriolar preservation of the retinal pigment epithelium (PPRPE). Retinal degenerations associated with nanophthalmos and hyperopia, or with keratoconus, can serve as further clinical cues to mutations in CRB1. Despite this, no clear genotype-phenotype relationship has been established in CRB1 disease. In CRB1-disease, as in other inherited retinal degenerations (IRDs), it is essential to diagnose the specific disease-causing gene for the disease as genetic therapy has progressed considerably in the last few years and might be applicable.
De Castro DK, Fay A, Wladis EJ, Nguyen J, Osaki T, Metson R, Curry W. Self-irrigating piezoelectric device in orbital surgery. Ophthalmic Plast Reconstr Surg 2013;29(2):118-22.Abstract
PURPOSE: Orbital osteotomy risks injury to the eyeball and orbit soft tissues. Used extensively in oral and maxillofacial surgery, piezoelectric technology offers a greater margin of safety than traditional bone cutting instruments. The authors describe the novel use of this system in a variety of orbital surgeries. METHODS: This interventional case series was performed in accordance with institutional review board regulations. The medical records of all patients who had undergone orbital surgery using the piezoelectric blade at 3 institutions were reviewed. Indication for surgery, gender, age, duration of follow up, intraoperative complications, surgical result, and postoperative course was recorded. RESULTS: Sixteen patients underwent surgery on 18 orbits using the piezoelectric system between August 2011 and June 2012. Surgeries performed included orbital decompression (8), lateral orbitotomy (5), cranio-orbitotomy (4), and external dacryocystorhinostomy (1). Eight were female and 8 were male patients. Mean age was 55 years old (standard deviation 15 years). Mean follow up was 82 days. The osteotomy created by the blade was narrow and smooth in every case. The surgeons uniformly appreciated the precision and safety of the instrument compared with traditional electric saw blades. There were no soft tissue lacerations or intraoperative complications and reconstructions were uniformly uneventful. Postoperative healing was rapid with no unexpected inflammation, and no palpable bony defects were appreciated in the reconstructed cases. CONCLUSIONS: Because it does not cut soft tissue and cuts a narrow trough, the self-irrigating piezoelectric saw blade appears safer and more precise than traditional electric saw blades in and around the orbit.
Connors EC, Yazzolino LA, Sánchez J, Merabet LB. Development of an audio-based virtual gaming environment to assist with navigation skills in the blind. J Vis Exp 2013;(73)Abstract
Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.
Blanco-Mezquita JT, Hutcheon AEK, Zieske JD. Role of thrombospondin-1 in repair of penetrating corneal wounds. Invest Ophthalmol Vis Sci 2013;54(9):6262-8.Abstract
PURPOSE: Thrombospondin-1 (THBS1) has been suggested as a corneal wound-healing modulator. Therefore, we compromised the integrity of the cornea to elucidate the role of THBS1. METHODS: Full-thickness penetrating corneal incisions (1.5 mm) were created in wild type (WT, 129S2/SvPas) and THBS1-deficient mice (Thbs1⁻/⁻), 129S2/SvPas-Thbs1(tm1Hyn)/Thbs1(tm1Hyn)), and allowed to heal up to 1 month, while being monitored by slit-lamp and intravital corneal examinations. Corneas also were examined by transmission electron microscopy and indirect immunofluorescence. To determine how THBS1 was involved in the healing process, we examined THBS1 and α-smooth muscle actin (SMA), a marker of myofibroblasts and myoepithelial cells. RESULTS: In WT mice by 1 month, corneas appeared transparent with a thin scar, and endothelium and Descemet's membrane (DM) were restored. In contrast, Thbs1⁻/⁻ corneas exhibited chronic edema and persistent opacity after wounding. The DM and endothelium were not restored, and wound contraction was impaired. The THBS1 was localized in epithelial cells at early stages of the healing process, and in the stroma and endothelial cells during later stages. The SMA-positive epithelial cells and myofibroblasts were observed within the healing area at day 4, peaked at day 14, and disappeared at day 30. The SMA-positive cells were reduced greatly in Thbs1⁻/⁻ mice. CONCLUSIONS: In the current study, we demonstrated that corneal restoration is strikingly compromised by a penetrating incision in Thbs1⁻/⁻ mice. The wound results in persistent edema and wound gaping. This appears to be the result of the lack of endothelial migration and DM restoration. In addition, myofibroblast formation is compromised, resulting in the lack of wound contraction.