The potential of stem cell-based therapy for retinal repair. Neural Regen Res 2014;9(11):1100-3..
Good visual outcome after repair of a very large macular hole with neurosensory retinal operculum. Retin Cases Brief Rep 2014;8(2):138-40.Abstract.
PURPOSE: To describe a favorable outcome after the surgical repair of a very large macular hole with a neurosensory operculum. METHODS: Case report. A 42-year-old man with a history of decreased vision for 3 months was found to have vision of 20/400, a very large macular hole (1159 μm in diameter), and an operculum suspended on the posterior hyaloid above the hole. RESULTS: Vitrectomy and internal limiting membrane peel were performed. The operculum was processed for histology and found to contain neurons and glial cells. Fourteen months later, the patient's vision improved to 20/60. CONCLUSION: Very large macular holes have traditionally been considered to have a poor prognosis. Here, we demonstrate that such large holes can be repaired with good visual outcome, even in the setting of an operculum consisting of avulsed neural retina.
Membrane guanylyl cyclase complexes shape the photoresponses of retinal rods and cones. Front Mol Neurosci 2014;7:45.Abstract.
In vertebrate rods and cones, photon capture by rhodopsin leads to the destruction of cyclic GMP (cGMP) and the subsequent closure of cyclic nucleotide gated ion channels in the outer segment plasma membrane. Replenishment of cGMP and reopening of the channels limit the growth of the photon response and are requisite for its recovery. In different vertebrate retinas, there may be as many as four types of membrane guanylyl cyclases (GCs) for cGMP synthesis. Ten neuronal Ca(2+) sensor proteins could potentially modulate their activities. The mouse is proving to be an effective model for characterizing the roles of individual components because its relative simplicity can be reduced further by genetic engineering. There are two types of GC activating proteins (GCAPs) and two types of GCs in mouse rods, whereas cones express one type of GCAP and one type of GC. Mutant mouse rods and cones bereft of both GCAPs have large, long lasting photon responses. Thus, GCAPs normally mediate negative feedback tied to the light-induced decline in intracellular Ca(2+) that accelerates GC activity to curtail the growth and duration of the photon response. Rods from other mutant mice that express a single GCAP type reveal how the two GCAPs normally work together as a team. Because of its lower Ca(2+) affinity, GCAP1 is the first responder that senses the initial decrease in Ca(2+) following photon absorption and acts to limit response amplitude. GCAP2, with a higher Ca(2+) affinity, is recruited later during the course of the photon response as Ca(2+) levels continue to decline further. The main role of GCAP2 is to provide for a timely response recovery and it is particularly important after exposure to very bright light. The multiplicity of GC isozymes and GCAP homologs in the retinas of other vertebrates confers greater flexibility in shaping the photon responses in order to tune visual sensitivity, dynamic range and frequency response.
Age-related macular degeneration and the incidence of cardiovascular disease: a systematic review and meta-analysis. PLoS One 2014;9(3):e89600.Abstract.
IMPORTANCE: Research has indicated some shared pathogenic mechanisms between age-related macular degeneration (AMD) and cardiovascular disease (CVD). However, results from prior epidemiologic studies have been inconsistent as to whether AMD is predictive of future CVD risk. OBJECTIVE: To systematically review population-based cohort studies of the association between AMD and risk of total CVD and CVD subtypes, coronary heart disease (CHD) and stroke. DATA SOURCES: A systematic search of the PubMed and EMBASE databases and reference lists of key retrieved articles up to December 20, 2012 without language restriction. DATA EXTRACTION: Two reviewers independently extracted data on baseline AMD status, risk estimates of CVD and methods used to assess AMD and CVD. We pooled relative risks using random or fixed effects models as appropriate. RESULTS: Thirteen cohort studies (8 prospective and 5 retrospective studies) with a total of 1,593,390 participants with 155,500 CVD events (92,039 stroke and 62,737 CHD) were included in this meta-analysis. Among all studies, early AMD was associated with a 15% (95% CI, 1.08-1.22) increased risk of total CVD. The relative risk was similar but not significant for late AMD (RR, 1.17; 95% CI, 0.98-1.40). In analyses restricted to the subset of prospective studies, the risk associated with early AMD did not appreciably change; however, there was a marked 66% (95% CI, 1.31-2.10) increased risk of CVD among those with late AMD. CONCLUSION: Whereas the results from all cohort studies suggest that both early and late AMD are predictive of a small increase in risk of future CVD, subgroup analyses limited to prospective studies demonstrate a markedly increased risk of CVD among people with late AMD. Retrospective studies using healthcare databases may have inherent methodological limitations that obscure such association. Additional prospective studies are needed to further elucidate the associations between AMD and specific CVD outcomes.
Displacement of optical centers in over-the-counter readers: a potential cause of diplopia. J AAPOS 2014;18(3):293-4.Abstract.
Induced prism in spectacle lenses, which may result from inadvertent displacement of optical centers, may worsen an existing heterophoria or even cause diplopia, yet over-the-counter reading glasses (OTC readers) are not always assessed by clinicians when evaluating patients with diplopia or asthenopia. To gauge the magnitude of this potential problem, we used a focimeter and prescription aligner to assess the frequency and extent of clinically significant manufacturing variations in a random selection of 160 OTC readers. The optical centers were vertically displaced by ≥3 mm in 11%, with a maximum displacement of 7 mm in 1 pair. Average interpupillary distance was 64 mm (range, 58-74.5 mm), with interpupillary distance outside the normal range of 60-70 mm in 5%. Monocular pupillary distance was asymmetric by ≥5 mm in 4%. A 0.75 D power difference between lenses was measured in one pair of OTC readers. Some OTC readers have misaligned optical centers and other manufacturing defects that are of a magnitude sufficient to exacerbate a heterophoria and cause asthenopia or diplopia.
Autologous dermal grafts as posterior lamellar spacers in the management of lower eyelid retraction. Ophthalmic Plast Reconstr Surg 2014;30(1):64-8.Abstract.
PURPOSE: To determine the safety and efficacy of autologous postauricular dermal grafts as posterior lamellar spacing material in patients with lower eyelid retraction. METHODS: At a tertiary care institution, 10 eyelids of 10 patients (7 men, 3 women; mean 56 years, range 24-78) who underwent repair of lower eyelid retraction using a postauricular dermal graft between July 2008 and December 2010 were retrospectively assessed. Data collected included patient demographics, etiology of retraction, and surgical history. Outcome measures included preoperative and postoperative eyelid position and surgery-related complications. RESULTS: Postoperative results were favorable: mean preoperative inferior scleral show was 3.3 ± 2.6 mm compared with 0.3 ± 1.2 mm postoperatively, p = 0.004 (paired t test). Mean follow up was 39.2 weeks (range 12-94). Complications included keratinization of the graft with vellus hair growth (n = 1) and ectropion (n = 1), both corrected with minor surgical interventions. One patient achieved overcorrection but declined further treatment. No donor site complications were encountered. CONCLUSIONS: These data suggest postauricular dermal grafts are effective posterior lamellar spacers in the correction of eyelid retraction. They have adequate rigidity whilst maintaining sufficient pliability to mold to the globe. Resorption, common to acellular dermis matrix allografts and xenografts, was not encountered. Donor site complications were not encountered. Complications shared with other material include overcorrection and ectropion. Complications unique to autologous dermis include keratinization and hair growth.
Disruption of the blood-aqueous barrier and lens abnormalities in mice lacking lysyl oxidase-like 1 (LOXL1). Invest Ophthalmol Vis Sci 2014;55(2):856-64.Abstract.
PURPOSE: Exfoliation syndrome (ES) is commonly associated with glaucoma, premature cataracts, and other ocular and systemic pathologies. LOXL1 gene variants are significantly associated with ES; however, the role of the protein in ES development remains unclear. The purpose of this study was to characterize the ocular phenotype in Loxl1(-/-) (null) mice. METHODS: Loxl1 null mice and strain-matched controls (C57BL) were evaluated by clinical and histologic analyses. RESULTS: Anterior segment histology showed a pronounced vesiculation of the anterior lens in the null mice. The lesions were subcapsular and in direct apposition with the posterior iris surface. Fluorescein angiography showed increased diffusion of fluorescein into the anterior chamber of the null mice compared with age-matched controls (P = 0.003, two-tailed, unequal variance t-test), suggesting compromise of the blood-aqueous barrier. Intraocular pressure measurements were within the normal range (16.5 ± 2.0 mm Hg) in null mice up to 1 year of age. Immunohistochemistry showed decreased elastin in the iris and ciliary body in the null mouse compared with controls. CONCLUSIONS: Elimination of LOXL1 in mice impairs the blood-aqueous humor barrier in the ocular anterior segment and causes lens abnormalities consistent with cataract formation, but does not result in deposition of macromolecular material or glaucoma. These results show that mice lacking LOXL1 have some ES features but that complete disease manifestation requires other factors that could be genetic and/or environmental.
Pharmacological regulation of SPARC by lovastatin in human trabecular meshwork cells. Invest Ophthalmol Vis Sci 2014;55(3):1657-65.Abstract.
PURPOSE: Statins have been shown to increase aqueous outflow facility. The matricellular protein SPARC (secreted protein acidic and rich in cysteine) is a critical mediator of aqueous outflow and intraocular pressure (IOP). Here, we examine the effects of lovastatin on SPARC expression in trabecular meshwork (TM) cells, exploring the molecular mechanisms involved. METHODS: Primary cultured human TM cells were incubated for 24, 48, and 72 hours with 10 μM lovastatin. In separate cultures, media was supplemented with either farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP) for the duration of the 72-hour time point experiment. Trabecular meshwork cells were also pretreated for 24 hours with lovastatin followed by 24-hour stimulation with 3 ng/mL TGF-β2. Cell lysates and media were harvested and relative mRNA and protein level changes were determined. Krüppel-like factor 4 (KLF4) localization in normal human anterior segments was examined by immunofluorescence. Adenovirus expressing human KLF4 was used and relative changes in SPARC mRNA and protein levels were assessed. RESULTS: Incubating TM cells with lovastatin suppressed SPARC mRNA and protein levels. This effect was reversed upon media supplementation with GGPP but not FPP. Pretreating cells with lovastatin inhibited TGF-β2 induction of SPARC. The KLF4 transcription factor was expressed throughout the TM and the inner and outer walls of Schlemm's canal. Lovastatin treatment upregulated KLF4 mRNA and protein levels. Overexpression of KLF4 downregulated SPARC expression. CONCLUSIONS: Collectively, our data identify lovastatin as an important pharmacological suppressor of SPARC expression in TM cells, and provide further insight into the molecular mechanisms mediating statin enhancement of aqueous outflow facility.
Short temporal asynchrony disrupts visual object recognition. J Vis 2014;14(5):7.Abstract.
Humans can recognize objects and scenes in a small fraction of a second. The cascade of signals underlying rapid recognition might be disrupted by temporally jittering different parts of complex objects. Here we investigated the time course over which shape information can be integrated to allow for recognition of complex objects. We presented fragments of object images in an asynchronous fashion and behaviorally evaluated categorization performance. We observed that visual recognition was significantly disrupted by asynchronies of approximately 30 ms, suggesting that spatiotemporal integration begins to break down with even small deviations from simultaneity. However, moderate temporal asynchrony did not completely obliterate recognition; in fact, integration of visual shape information persisted even with an asynchrony of 100 ms. We describe the data with a concise model based on the dynamic reduction of uncertainty about what image was presented. These results emphasize the importance of timing in visual processing and provide strong constraints for the development of dynamical models of visual shape recognition.
Biomechanical characterization of keratoconus corneas ex vivo with Brillouin microscopy. Invest Ophthalmol Vis Sci 2014;55(7):4490-5.Abstract.
PURPOSE: Loss of corneal strength is a central feature of keratoconus progression. However, it is currently difficult to measure corneal mechanical changes noninvasively. The objective of this study is to evaluate if Brillouin optical microscopy can differentiate the mechanical properties of keratoconic corneas versus healthy corneas ex vivo. METHODS: We obtained eight tissue samples from healthy donor corneas used in Descemet's stripping endothelial keratoplasty (DSEK) and 10 advanced keratoconic corneas from patients undergoing deep anterior lamellar keratoplasty (DALK). Within 2 hours after surgery, a confocal Brillouin microscope using a monochromatic laser at 532 nm was used to map the Brillouin frequency shifts of the corneas. RESULTS: The mean Brillouin shift in the anterior 200 μm of the keratoconic corneas at the cone was measured to be 7.99 ± 0.10 GHz, significantly lower than 8.17 ± 0.06 GHz of the healthy corneas (P < 0.001). The Brillouin shift in the keratoconic corneas decreased with depth from the anterior toward posterior regions with a steeper slope than in the healthy corneas (P < 0.001). Within keratoconic corneas, the Brillouin shift in regions away from the apex of the cone was significantly higher than within the cone region (P < 0.001). CONCLUSIONS: Brillouin measurements revealed notable differences between healthy and keratoconic corneas. Importantly, Brillouin imaging showed that the mechanical loss is primarily concentrated within the area of the keratoconic cone. Outside the cone, the Brillouin shift was comparable with that of healthy corneas. The results demonstrate the potential of Brillouin microscopy for diagnosis and treatment monitoring of keratoconus.
Predictors and outcomes of ocular hypertension after open-globe injury. J Glaucoma 2014;23(1):5-10.Abstract.
PURPOSE: Evaluate predictors and outcomes of ocular hypertension after open-globe injury. PATIENTS AND METHODS: This is a retrospective, case-control study reviewing records of consecutive patients with open-globe injuries treated at Massachusetts Eye and Ear Infirmary between February 1999 and January 2007. Of 658 patients treated, 382 had at least 2 months of follow-up and sufficient data to be included. Main outcome measures are visual acuity, intraocular pressure (IOP), and type of glaucoma intervention employed. RESULTS: Sixty-five (17%) patients developed ocular hypertension defined as IOP≥22 mm Hg at >1 visit or requiring treatment. Increased age (P<0.001), hyphema (0.025), lens injury (P<0.0001), and zone II injury (P=0.0254) are risk factors for developing ocular hypertension after open-globe injury. Forty-eight (74%) patients with ocular hypertension were treated medically, 8 (12%) underwent filtering or glaucoma drainage device surgery, 5 (8%) had IOP normalization with observation, while 4 (6%) required anterior chamber washout with no other glaucoma surgery. Patients with ocular hypertension had an average maximum IOP=33.4 mm Hg at a median follow-up of 21 days, with most patients maintaining normal IOP at all follow-up time points. Visual acuity improved over time with median acuity of hand motions preoperatively, and 20/60 at 12 and 36 months. CONCLUSIONS: Ocular hypertension is a significant complication after open-globe injury that sometimes requires surgical intervention. Predictive factors can alert physicians to monitor for elevated IOP in the first month after trauma. Most patients with traumatic ocular hypertension had improved visual acuity and IOP normalization over time.
Ectopic (choristomatous) orbital respiratory cyst: histopathology and immunohistochemistry. Surv Ophthalmol 2014;59(3):328-33.Abstract.
A 24-year-old woman underwent excision of a slowly growing mass located in the right superomedial orbit that had histopathologic and immunohistochemical findings consistent with a choristomatous respiratory cyst. This rare condition may either arise primarily from embryologic respiratory epithelium rests in the orbit or develop secondarily as the result of trauma or chronic sinus disease complicated by mucocele formation.
Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis. FASEB J 2014;28(9):3942-51.Abstract.
Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss. Biomarkers and methods for early diagnosis of DR are urgently needed. Using a new molecular imaging approach, we show up to 94% higher accumulation of custom designed imaging probes against vascular endothelial growth factor receptor 2 (VEGFR-2) in retinal and choroidal vessels of diabetic animals (P<0.01), compared to normal controls. More than 80% of the VEGFR-2 in the diabetic retina was in the capillaries, compared to 47% in normal controls (P<0.01). Angiography in rabbit retinas revealed microvascular capillaries to be the location for VEGF-A-induced leakage, as expressed by significantly higher rate of fluorophore spreading with VEGF-A injection when compared to vehicle control (26±2 vs. 3±1 μm/s, P<0.05). Immunohistochemistry showed VEGFR-2 expression in capillaries of diabetic animals but not in normal controls. Macular vessels from diabetic patients (n=7) showed significantly more VEGFR-2 compared to nondiabetic controls (n=5) or peripheral retinal regions of the same retinas (P<0.01 in both cases). Here we introduce a new approach for early diagnosis of DR and VEGFR-2 as a molecular marker. VEGFR-2 could become a key diagnostic target, one that might help to prevent retinal vascular leakage and proliferation in diabetic patients.
Immune privilege and the philosophy of immunology. Front Immunol 2014;5:110..
Activation of HIF-1α (hypoxia inducible factor-1α) prevents dry eye-induced acinar cell death in the lacrimal gland. Cell Death Dis 2014;5:e1309.Abstract.
The pathogenesis of immune-mediated lacrimal gland (LG) dysfunction in Sjögren's syndrome has been thoroughly studied. However, the majority of dry eye (DE) is not related to Sjögren type, and its pathophysiology remains unclear. The purpose of this study was to determine and investigate the protective mechanisms against DE stress in mice. DE induced prominent blood vessel loss without apoptosis or necrosis in the LG. Autophagic vacuoles, distressed mitochondria, and stressed endoplasmic reticulum were observed via electron microscopy. Immunoblotting confirmed the increase in autophagic markers. Glycolytic activities were enhanced with increasing levels of succinate and malate that, in turn, activated hypoxia-inducible factor (HIF)-1α. Interestingly, the areas of stable HIF-1α expression overlapped with COX-2 and MMP-9 upregulation in LGs of DE-induced mice. We generated HIF-1α conditional knockout (CKO) mice in which HIF-1α expression was lost in the LG. Surprisingly, normal LG polarities and morphologies were completely lost with DE induction, and tremendous acinar cell apoptosis was observed. Similar to Sjögren's syndrome, CD3(+) and CD11b(+) cells infiltrated HIF-1α CKO LGs. Our results show that DE induced the expression of HIF-1α that activated autophagy signals to prevent further acinar cell damage and to maintain normal LG function.