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    Genetics of Exfoliation Syndrome: New Locus Identified

    Nature Genetics
    Published online Feb. 23, 2015

    To better understand the etiology of exfoliation syndrome (XFS), Aung et al. conducted a genomewide association study. They found a significant association between a new locus—the first one identified outside of LOXL1—and increased susceptibility to XFS.

    The new locus is CACNA1A rs4926244; it emerged in the initial analysis of 1,484 cases of XFS and 1,188 controls, all of whom were of Japanese ancestry. The results were verified in an additional analysis of 6,901 cases and 20,727 controls from 17 countries. Overall, the results suggest that risk for XFS increases by approximately 1.6-fold for each copy of the minor G allele.

    Given the lack of information on CACNA1A expression in the eye, the researchers examined the mRNA and protein expression profiles of this gene in a variety of human ocular tissues and cell lines. They found mRNA expression in all of the ocular tissues they examined, with the exception of the optic nerve head. Distribution of CACNA1A was similar, whether or not the patient had XFS.

    GATT for Primary Congenital and Juvenile Open-Angle Glaucomas

    British Journal of Ophthalmology
    Published online Feb. 12, 2015

    How safe and effective is gonioscopy-assisted transluminal trabeculotomy (GATT), a minimally invasive and conjunctiva-sparing procedure, for treating primary congenital glaucoma (PCG) and juvenile open-angle glaucoma (JOAG)? Grover et al. evaluated the ab interno procedure in this setting and found that it can be used successfully to treat PCG and JOAG.

    For this retrospective chart review, the researchers evaluated 10 patients (14 eyes) who had undergone GATT and had been followed for at least 12 months (range, 12-33 months). At the time of treatment, patients’ ages ranged from 17 months to 30 years.

    The only complication that occurred during or after surgery was early postoperative hyphema in five eyes (36 percent); this cleared by one month in all eyes. The mean intraocular pressure dropped from 27.3 mmHg to 14.8 mmHg, and the mean number of medications required dropped from 2.6 to 0.86. In addition, all patients were examined by gonioscopy after the third month following GATT surgery; at that time, all of the eyes had an open trabecular shelf in more than 180 degrees of the angle.

    The authors state that GATT has two primary advantages: 1) Unlike the traditional ab externo approach, it does not involve extensive conjunctival dissection or an invasive scleral flap; and 2) unlike goniotomy, it opens 360 degrees of the angle. However, they acknowledge that the procedure requires a surgical learning curve.

    Optic Neuritis and Presence of Selected Autoantibodies

    JAMA Neurology
    2015;72(2):187-193

    Martinez-Hernandez et al. investigated the frequency of selected autoantibodies in patients with isolated optic neuropathy (ON). They found that the presence of antibodies to aquaporin 4 (AQP4) has diagnostic and prognostic value, but the significance of antibodies to myelin-oligodendrocyte glycoprotein (MOG) and the glycine receptor α1 subunit (GlyR) remains unclear at this time.

    For this retrospective case-control study, the researchers evaluated 51 patients with ON and 142 patients who served as controls. Of the control group, 30 individuals were healthy, 48 had neuromyelitis optica (NMO), and 64 had multiple sclerosis (MS). No clinical or magnetic resonance imaging findings outside the optic nerve were available for the ON patients.

    Serum antibodies were detected in 23 (45 percent) of the ON patients, including MOG in 10 patients, AQP4 in six, and GlyR in seven (concurrent with MOG in three ON patients and with AQP4 in one patient). Those with AQP4 antibodies had a worse visual outcome, while those with MOG had a better outcome, similar to that of seronegative patients.

    Antibody levels in the control group varied widely: 1) Of the 48 patients with NMO, 37 (77 percent) had AQP4 antibodies, four (8 percent) had MOG antibodies, two (4 percent) had AQP4 antibodies concurrent with MOG antibodies, and five (10 percent) were seronegative. None had GlyR antibodies. 2) Of the 64 patients with MS, five (8 percent) had GlyR antibodies, and none had AQP4 or MOG antibodies. 3) All of the 30 healthy individuals were seronegative.

    Cell Differentiation by OCT in Anterior Uveitis

    Investigative Ophthalmology and Visual Science
    2015;56(3):1430-1436

    Rose-Nussbaumer et al. used optical coherence tomography (OCT) to evaluate the characteristics of inflammatory cells both in vitro and in vivo. They found that cells in uveitis patients appeared as hyperreflective spots, indicating that OCT has potential as a noninvasive method of evaluating cells in the anterior chamber.

    For this study, the researchers prepared blood from two healthy volunteers and used custom software algorithms to identify cells based on their reflectance distribution. These algorithms were then applied to OCT images obtained from 14 uveitis patients (19 eyes) with active anterior chamber inflammation.

    On OCT images, the cells appeared as hyperreflective spots. In vitro, the cell reflectance differed among all of the cell types. In vivo imaging revealed a relationship between underlying disease and cell type: The uveitis patients affected by sarcoidosis and inflammatory bowel disease had a predominantly mononuclear pattern on OCT, while those with HLA-B27–associated disease had a predominantly polymorphonuclear pattern.

    The researchers noted that this technique could potentially have other applications, such as identifying malignant cells in the aqueous.

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    Roundup of Other Journals is written by Jean Shaw and edited by Deepak P. Edward, MD.

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