Factors Affecting Ophthalmology Resident Choice to Pursue Neuro-Ophthalmology Fellowship Training.

BACKGROUND: The number of ophthalmology-trained residents applying to neuro-ophthalmology fellowships has not increased despite a trend toward seeking fellowship training after residency. This study sought to identify factors affecting the choice to pursue or not pursue neuro-ophthalmology fellowship training by graduating ophthalmology residents and recently graduated neuro-ophthalmology fellows. METHODS: An anonymous survey was sent to Association of University Professors of Ophthalmology residency directors to distribute to post-graduate Year 4 (PGY4) ophthalmology residents graduating in either 2018 or 2019. A second anonymous survey was distributed via the North American Neuro-Ophthalmology Society (NANOS) Young Neuro-Ophthalmologists listserv to ophthalmology-trained neuro-ophthalmology fellows. A total of 147 respondents, including 96 PGY4 ophthalmology residents not going into neuro-ophthalmology and 51 practicing neuro-ophthalmologists are included. RESULTS: The most common reasons for residents to choose to not pursue further training in neuro-ophthalmology included a stronger interest in other fields, types of patients seen, no intraocular surgery, and the assumption that it is a nonsurgical discipline. The leading factors influencing graduated, ophthalmology-trained fellows to choose neuro-ophthalmology included interest in the clinical diseases treated, interaction with other specialty fields, and a supportive NANOS culture. Interestingly, despite perceptions of graduating residents, two-thirds of the neuro-ophthalmologists surveyed perform surgery. There were no differences between the 2 groups with respect to the degree of exposure to neuro-ophthalmology in medical school, presence of a dedicated neuro-ophthalmology rotation in residency, or timing of the rotation. CONCLUSIONS: There are a variety of factors influencing decisions regarding pursuing neuro-ophthalmology fellowship among ophthalmology residents. The perceived lack of surgical opportunities in neuro-ophthalmology is a deterrent for many. However, a significant number of neuro-ophthalmologists continue to perform surgery, including intraocular surgery. Repeated exposure later in residency may provide an opportunity to reconsider the field and to re-emphasize opportunities to remain surgically involved as a neuro-ophthalmologist. Exposure to the practice patterns of recently graduated neuro-ophthalmologists offers residents in training excellent exposure to the contemporary practice of neuro-ophthalmology. Hence, ensuring trainees receive a balanced exposure to practicing neuro-ophthalmologists across the spectrum of seniority and scope of practice may promote greater interest among ophthalmology residents to pursue a career in neuro-ophthalmology.

Multiple cell types form the VIP amacrine cell population.

Amacrine cells are a heterogeneous group of interneurons that form microcircuits with bipolar, amacrine and ganglion cells to process visual information in the inner retina. This study has characterized the morphology, neurochemistry and major cell types of a VIP-ires-Cre amacrine cell population. VIP-tdTomato and -Confetti (Brainbow2.1) mouse lines were generated by crossing a VIP-ires-Cre line with either a Cre-dependent tdTomato or Brainbow2.1 reporter line. Retinal sections and whole-mounts were evaluated by quantitative, immunohistochemical, and intracellular labeling approaches. The majority of tdTomato and Confetti fluorescent cell bodies were in the inner nuclear layer (INL) and a few cell bodies were in the ganglion cell layer (GCL). Fluorescent processes ramified in strata 1, 3, 4, and 5 of the inner plexiform layer (IPL). All tdTomato fluorescent cells expressed syntaxin 1A and GABA-immunoreactivity indicating they were amacrine cells. The average VIP-tdTomato fluorescent cell density in the INL and GCL was 535 and 24 cells/mm2 , respectively. TdTomato fluorescent cells in the INL and GCL contained VIP-immunoreactivity. The VIP-ires-Cre amacrine cell types were identified in VIP-Brainbow2.1 retinas or by intracellular labeling in VIP-tdTomato retinas. VIP-1 amacrine cells are bistratified, wide-field cells that ramify in strata 1, 4, and 5, VIP-2A and 2B amacrine cells are medium-field cells that mainly ramify in strata 3 and 4, and VIP-3 displaced amacrine cells are medium-field cells that ramify in strata 4 and 5 of the IPL. VIP-ires-Cre amacrine cells form a neuropeptide-expressing cell population with multiple cell types, which are likely to have distinct roles in visual processing.

Nogo receptor 1 is expressed by nearly all retinal ganglion cells.

A variety of conditions ranging from glaucoma to blunt force trauma lead to optic nerve atrophy. Identifying signaling pathways for stimulating axon growth in the optic nerve may lead to treatments for these pathologies. Inhibiting signaling by the nogo-66 receptor 1 (NgR1) promotes the re-extension of axons following a crush injury to the optic nerve, and while NgR1 mRNA and protein expression are observed in the retinal ganglion cell (RGC) layer and inner nuclear layer, which retinal cell types express NgR1 remains unknown. Here we determine the expression pattern of NgR1 in the mouse retina by co-labeling neurons with characterized markers of specific retinal neurons together with antibodies specific for NgR1 or Green Fluorescent Protein expressed under control of the ngr1 promoter. We demonstrate that more than 99% of RGCs express NgR1. Thus, inhibiting NgR1 function may ubiquitously promote the regeneration of axons by RGCs. These results provide additional support for the therapeutic potential of NgR1 signaling in reversing optic nerve atrophy.

Distinct Circuits for Recovery of Eye Dominance and Acuity in Murine Amblyopia.

Degrading vision by one eye during a developmental critical period yields enduring deficits in both eye dominance and visual acuity. A predominant model is that "reactivating" ocular dominance (OD) plasticity after the critical period is required to improve acuity in amblyopic adults. However, here we demonstrate that plasticity of eye dominance and acuity are independent and restricted by the nogo-66 receptor (ngr1) in distinct neuronal populations. Ngr1 mutant mice display greater excitatory synaptic input onto both inhibitory and excitatory neurons with restoration of normal vision. Deleting ngr1 in excitatory cortical neurons permits recovery of eye dominance but not acuity. Reciprocally, deleting ngr1 in thalamus is insufficient to rectify eye dominance but yields improvement of acuity to normal. Abolishing ngr1 expression in adult mice also promotes recovery of acuity. Together, these findings challenge the notion that mechanisms for OD plasticity contribute to the alterations in circuitry that restore acuity in amblyopia.

Expression of voltage-gated calcium channel α(2)δ(4) subunits in the mouse and rat retina.

High-voltage activated Ca channels participate in multiple cellular functions, including transmitter release, excitation, and gene transcription. Ca channels are heteromeric proteins consisting of a pore-forming α(1) subunit and auxiliary α(2)δ and ß subunits. Although there are reports of α(2)δ(4) subunit mRNA in the mouse retina and localization of the α(2)δ(4) subunit immunoreactivity to salamander photoreceptor terminals, there is a limited overall understanding of its expression and localization in the retina. α(2)δ(4) subunit expression and distribution in the mouse and rat retina were evaluated by using reverse transcriptase polymerase chain reaction, western blot, and immunohistochemistry with specific primers and a well-characterized antibody to the α(2)δ(4) subunit. α(2)δ(4) subunit mRNA and protein are present in mouse and rat retina, brain, and liver homogenates. Immunostaining for the α(2)δ(4) subunit is mainly localized to Müller cell processes and endfeet, photoreceptor terminals, and photoreceptor outer segments. This subunit is also expressed in a few displaced ganglion cells and bipolar cell dendrites. These findings suggest that the α(2)δ(4) subunit participates in the modulation of L-type Ca(2+) current regulating neurotransmitter release from photoreceptor terminals and Ca(2+)-dependent signaling pathways in bipolar and Müller cells.

The pituitary gland: a brief history.

The functions of the pituitary gland as an important constituent of the endocrine system were not understood until the latter part of the nineteenth century and the first half of the 20th century. At one time, the pituitary was deemed to be the "leader of the endocrine orchestra," but more recent studies have shown that its secretions are influenced by external stimuli and that it is largely under the control of the hypothalamus.