Reversible inhibition of the basal ganglia prolongs repetitive vocalization but only weakly affects sequencing at branch points in songbirds.

Although vocal signals, including languages and songbird syllables, are composed of a finite number of acoustic elements, diverse vocal sequences are composed of a combination of these elements, which are linked together by syntactic rules. However, the neural basis of syntactic vocalization generation remains poorly understood. Here, we report that inhibition using tetrodotoxin (TTX) and manipulations of gamma-aminobutyric acid (GABA) receptors within the basal ganglia Area X or lateral magnocellular nucleus of the anterior neostriatum (LMAN) alter and prolong repetitive vocalization in Bengalese finches (Lonchura striata var. domestica). These results suggest that repetitive vocalizations are modulated by the basal ganglia and not solely by higher motor cortical neurons. These data highlight the importance of neural circuits, including the basal ganglia, in the production of stereotyped repetitive vocalizations and demonstrate that dynamic disturbances within the basal ganglia circuitry can differentially affect the repetitive temporal features of songs.

Relationship between Full-Thickness Macular Hole Onset and Posterior Vitreous Detachment: A Temporal Onset Theory.

Purpose: To evaluate the relationship between full-thickness macular hole (FTMH) onset and perifoveal posterior vitreous detachment using OCT data. Design: Retrospective study. Participants: A total of 742 patients with FTMH or impending macular hole (MH) in ≥ 1 eye, as determined by ophthalmoscopy and OCT. Methods: Macular holes were staged using OCT results. Patients with the posterior vitreous membrane clearly detected in the OCT images and vitreoretinal adhesion size ≤ 1500 µm-eyes with MH stages 1-3-were included in the study. The contralateral eyes were also included in the analyses if they showed the focal type of vitreomacular adhesion (VMA) (i.e., vitreoretinal adhesion ≤ 1500 µm). The distance between the posterior vitreous membrane and the surface of the retina was defined as the posterior vitreous separation height (PVSH). Using the OCT images, PVSHs of each eye in 4 directions (nasal, temporal, superior, and inferior) at 1 mm from the center of the MH or fovea were calculated. Main Outcome Measures: The main outcome measures were PVSHs according to the MH stage and VMA, the relationship of the foveal inner tear with PVSH, and the likelihood of a foveal inner tear based on the direction. Results: The PVSH trends in each of the 4 directions were as follows: VMA < MH stage 1 = MH stage 2 < MH stage 3. Initial MH stage 2 (onset of FTMH) was defined as the presence of a gap in only 1 of the 4 directions from the center of the MH. With increased PVSH, the likelihood of a gap increased (P = 0.002), and a temporal gap was more likely to occur than a nasal gap (P = 0.002). Conclusions: At FTMH onset, a foveal inner tear likely appears on the temporal side or the side showing a high PVSH value. Financial Disclosures: The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Upper Eyelid Meibomian Gland Dysfunction is a Risk Factor for Dry Eye Symptoms Following Cataract Surgery in the Early Phase.

PURPOSE: To evaluate perioperative dry eye (DE) syndrome and meibomian gland (MG) dysfunction parameters associated with cataract surgery-induced DE symptoms. PATIENTS AND METHODS: This retrospective, single-centered, observational study included 82 eyes of 43 patients without previous subjective DE symptoms, treatment, ocular comorbidities, and previous use of ophthalmic treatment, except for anti-allergic eye drops, who underwent uncomplicated cataract surgery. MG dropout, lid margin abnormality, meibum quality, meibum expressibility, MG orifice obstruction, ocular surface disease index, non-invasive tear break-up time, tear meniscus height, and Schirmer test score were measured at baseline and 1 month postoperatively. Multivariable logistic regression with generalized estimating equation models was used to determine the risk factors for cataract surgery-induced DE symptoms. RESULTS: Twenty-one patients had subjective DE symptoms 1 month following the cataract surgery. Preoperative and postoperative parameters, preoperative upper eyelid MG loss, and female sex (odds ratio [OR] 6.72, P = 0.012; OR 4.20, P = 0.037, respectively) were identified as risk factors for cataract surgery-induced DE symptoms. CONCLUSION: Ocular parameters, including upper eyelid MG findings at baseline, were considered important in predicting persistent DE symptoms following cataract surgery.

Kv4.2-Positive Domains on Dendrites in the Mouse Medial Geniculate Body Receive Ascending Excitatory and Inhibitory Inputs Preferentially From the Inferior Colliculus.

The medial geniculate body (MGB) is the thalamic center of the auditory lemniscal pathway. The ventral division of MGB (MGV) receives excitatory and inhibitory inputs from the inferior colliculus (IC). MGV is involved in auditory attention by processing descending excitatory and inhibitory inputs from the auditory cortex (AC) and reticular thalamic nucleus (RTN), respectively. However, detailed mechanisms of the integration of different inputs in a single MGV neuron remain unclear. Kv4.2 is one of the isoforms of the Shal-related subfamily of potassium voltage-gated channels that are expressed in MGB. Since potassium channel is important for shaping synaptic current and spike waveforms, subcellular distribution of Kv4.2 is likely important for integration of various inputs. Here, we aimed to examine the detailed distribution of Kv4.2, in MGV neurons to understand its specific role in auditory attention. We found that Kv4.2 mRNA was expressed in most MGV neurons. At the protein level, Kv4.2-immunopositive patches were sparsely distributed in both the dendrites and the soma of neurons. The postsynaptic distribution of Kv4.2 protein was confirmed using electron microscopy (EM). The frequency of contact with Kv4.2-immunopositive puncta was higher in vesicular glutamate transporter 2 (VGluT2)-positive excitatory axon terminals, which are supposed to be extending from the IC, than in VGluT1-immunopositive terminals, which are expected to be originating from the AC. VGluT2-immunopositive terminals were significantly larger than VGluT1-immunopositive terminals. Furthermore, EM showed that the terminals forming asymmetric synapses with Kv4.2-immunopositive MGV dendritic domains were significantly larger than those forming synapses with Kv4.2-negative MGV dendritic domains. In inhibitory axons either from the IC or from the RTN, the frequency of terminals that were in contact with Kv4.2-positive puncta was higher in IC than in RTN. In summary, our study demonstrated that the Kv4.2-immunopositive domains of the MGV dendrites received excitatory and inhibitory ascending auditory inputs preferentially from the IC, and not from the RTN or cortex. Our findings imply that time course of synaptic current and spike waveforms elicited by IC inputs is modified in the Kv4.2 domains.

Role of the Water Gradient Structure in Inhibiting Thin Aqueous Layer Break in Silicone Hydrogel-Soft Contact Lens.

Purpose: Soft contact lenses (SCLs) are effective for refractive error correction, but prolonged wear triggers discomfort and discontinuation. This study investigates whether water gradient technology of delefilcon A-based SCLs improve tear film dynamics. Methods: This retrospective observational study included 50 asymptomatic delefilcon A or narafilcon A users. Data on thin aqueous layer break (TALB; %), noninvasive tear break-up time (NIBUT), tear meniscus height (TMH; mm), subjective dryness, and higher-order aberrations (HOAs) were collected. Measurements of the bare eye, the SCL-worn eye after 15 minutes (visit 1 [v1]) and 30 ± 5 days after v1 after SCL was worn for ≥5 hours (visit 2 [v2]) were recorded. Results: TALB was significantly reduced in the delefilcon A group compared to the narafilcon A group (33.3% vs. 85.5% at v1; P < 0.0001 and 31.7% vs. 80.4% at v2; P < 0.0001). The NIBUT was also significantly higher in the former (4.2 ± 2.1 seconds vs. 2.9 ± 1.5 at v1; P < 0.01 and 4.1 ± 2.3 seconds vs. 2.7 ± 1.6 seconds at v2; P < 0.01) across both visits. The TMH was significantly reduced in the former in both v1 and v2. The total ocular HOAs were significantly lower in the former at v1 (P < 0.001) and v2 (P < 0.05) compared to the bare eye. Conclusions: The water gradient technology of delefilcon A reduces TALB and increases NIBUT. Translational Relevance: The use of water gradient technology improves tear film dynamics and alleviate pathological break-up pattern, improving lens performance.

The ROCK Inhibitor Ripasudil Shows an Endothelial Protective Effect in Patients With Low Corneal Endothelial Cell Density After Cataract Surgery.

Purpose: In the field of regenerative medicine, Rho kinase inhibitors (ROCK inhibitors) show a protective effect on the corneal endothelium and promote effective healing in acute surgical wounds. In this study, we investigated the effectiveness of eyedrops containing ripasudil, a ROCK inhibitor approved in Japan for therapeutic use for glaucoma. Methods: In this retrospective observational study, 13 glaucoma patients (16 eyes) were treated with 0.4% ripasudil eyedrops twice a day after cataract surgery. The control group comprised 13 patients (17 eyes). The averaged corneal endothelial cell density from one central and four paracentral points was <1500/mm2 (range, 527 to 1439/mm2). Results: The mean rate of increase in the thinnest corneal thickness one week after surgery was 1.25% in the ripasudil group, which was significantly lower than the 5.97% increase observed in the control group (P = 0.0037). The mean endothelial cell density loss 90 to 120 days after surgery, excluding bullous keratopathy patients for whom measurements were not possible was -4.5% in the ripasudil group, which was significantly lower than in control group (14.1%; P = 0.0003). Conclusions: The results suggest that ripasudil may help maintain corneal endothelial functional integrity and reduce cell loss after cataract surgery in patients with low corneal endothelial cell density, suggesting that it may be more broadly useful for protection of the corneal endothelium after intraocular surgery. Translational Relevance: The clinically approved ROCK inhibitor ripasudil formulated as an eye drop for glaucoma has a corneal endothelial protective effect in cataract surgery for patients with low corneal endothelial cell density.

Evaluation of corneal biomechanics in patients with keratectasia following LASIK using dynamic Scheimpflug analyzer.

PURPOSE: To investigate the corneal biomechanics in eyes with keratectasia following LASIK using a dynamic Scheimpflug analyzer. DESIGN: Case-Control study. METHOD: The subjects in the study included 12 eyes with keratectasia after LASIK (KE), 24 eyes with keratoconus (KC), 17 eyes without keratectasia after LASIK (LASIK), and 34 eyes with normal corneas (Normal). Corneal biomechanics of the four groups were evaluated using a dynamic Scheimpflug analyzer. RESULTS: Compared with Normal (7.06 ± 0.54), the radius at the highest concavity (radius, mm) of LASIK (5.96 ± 0.76), KE (4.93 ± 0.61) and KC (5.39 ± 1.02) were significantly small. The Deflection Amplitude (HCDLA, mm) of Normal (0.94 ± 0.07) was significantly lower than those of KE (1.11 ± 0.10) and KC (1.06 ± 0.16), and was not significantly different from that of LASIK (0.98 ± 0.07). There were significant differences between LASIK and KE in radius and HCDLA (P < 0.05), whereas KE and KC had no differences in these parameters. CONCLUSIONS: Corneal biomechanical features evaluated using the dynamic Scheimpflug analyzer suggest that biomechanical properties in eyes with keratectasia, keratoconus, and LASIK are different from those of normal eyes. Although the biomechanics in eyes with keratectasia differs from that in eyes with LASIK, it is similar to that in eyes with keratoconus.

Late postnatal shifts of parvalbumin and nitric oxide synthase expression within the GABAergic and glutamatergic phenotypes of inferior colliculus neurons.

The inferior colliculus (IC) is partitioned into three subdivisions: the dorsal and lateral cortices (DC and LC) and the central nucleus (ICC), and serves as an integration center of auditory information. Recent studies indicate that a certain population of IC neurons may represent the non-GABAergic phenotype, while they express well-established cortical/hippocampal GABAergic neuron markers. In this study we used the optical disector to investigate the phenotype of IC neurons expressing parvalbumin (PV) and/or nitric oxide synthase (NOS) in C57BL/6J mice during the late postnatal period. Four major types of IC neurons were defined by the presence (+) or absence (-) of PV, NOS, and glutamic acid decarboxylase 67 (GAD67): PV+ /NOS- /GAD67+ , PV+ /NOS+ /GAD67+ , PV+ /NOS- /GAD67- , and PV- /NOS+ /GAD67- . Fluorescent in situ hybridization for vesicular glutamate transporter 2 mRNA indicated that almost all GAD67- IC neurons represented the glutamatergic phenotype. The numerical densities (NDs) of total GAD67+ IC neurons remained unchanged in all subdivisions. The NDs of PV+ /NOS- /GAD67+ neurons and PV- /NOS+ /GAD67- neurons were reduced with age in the ICC, while they remained unchanged in the DC and LC. By contrast, the NDs of PV+ /NOS+ /GAD67+ neurons and PV+ /NOS- /GAD67- neurons were increased with age in the ICC, although there were no changes in the DC and LC. The cell body size of GAD67+ IC neurons did not vary according to the expression of PV with or without NOS. The present findings indicate that the expression of PV and NOS may shift with age within the GABAergic and glutamatergic phenotypes of IC neurons during the late postnatal period. J. Comp. Neurol. 525:868-884, 2017. © 2016 Wiley Periodicals, Inc.

Quantitative Evaluation of the Natural Progression of Keratoconus Using Three-Dimensional Optical Coherence Tomography.

PURPOSE: We quantified the chronologic progression of keratoconus using anterior segment optical coherence tomography (AS-OCT). METHODS: A total of 217 eyes from 113 patients with keratoconus, keratoconus suspect, or forme fruste keratoconus were evaluated by corneal tomography using swept-source OCT. Age-dependent changes in the radius of the posterior best-fit sphere (Rpost), minimum corneal thickness (Tmin), and distance from the thinnest point to the corneal vertex (Dmin) were examined over follow-up periods of up to 5.79 years and were analyzed using generalized estimating equation (GEE) nonlinear regression model. RESULTS: Annual changes in Rpost (mean, -0.017 mm) and Tmin (-2.69 µm) were significantly higher in younger patients (P < 0.01, GEE nonlinear regression) and in patients with higher maximal K value (Kmax; P < 0.01, GEE nonlinear regression), whereas no changes were observed in Dmin. Even in patients 30 years or older, 14% of eyes revealed remarkable progression in Rpost. In eyes with acute hydrops, annual changes in Rpost (-0.22 mm) and Tmin (-33.8 µm) before acute corneal hydrops were more than 10 times faster than those in other eyes (P < 0.001, GEE nonlinear regression). CONCLUSIONS: Chronologic measurements of corneal tomography in keratoconus demonstrated that the progression of steepening at posterior corneal surface was found not only in patients under 30 years but also in older patients, particularly in advanced keratoconus. The rate of progression can be measured by mapping of corneal curvature and thickness using OCT, and the risk of progression was greater in younger patients with steeper Kmax.

Regional Differences in Tear Film Stability and Meibomian Glands in Patients With Aqueous-Deficient Dry Eye.

OBJECTIVES: To noninvasively investigate regional differences in tear film stability and meibomian glands in patients with aqueous-deficient dry eye. METHODS: Forty-nine dry eyes and 31 normal eyes were analyzed. A corneal topographer with a tear film scanning function was used for noninvasive tear film break-up time (NI-TFBUT) measurements and meibomian gland observations. The NI-TFBUT values and location of the first tear film break-up point were recorded in four quadrants. Meibomian gland loss was graded for each eyelid using meiboscores. Lid margin abnormality was scored from zero to four according to the number of existing abnormalities. The NI-TFBUT values and meiboscores were compared between two groups, and regional differences in NI-TFBUT values and meiboscores were analyzed. Also, the correlation between the NI-TFBUT and ocular surface examination results were investigated. RESULTS: The NI-TFBUT values and meiboscores were significantly lower and higher, respectively, for the dry eye group than for the normal group. In the dry eye group, the occurrence rate for first tear film break-up was the highest in the inferior nasal quadrant, and the mean meiboscore was significantly higher for the upper eyelids than for the lower eyelids. The NI-TFBUT and lid margin abnormality scores showed a weak negative correlation, and the NI-TFBUT values and meiboscores showed no correlation. CONCLUSIONS: Compared to normal eyes, aqueous-deficient dry eyes show significant regional differences in tear film stability and meibomian glands. Considering these regional differences, the overall observation of the ocular surface, including both upper and lower eyelids, will aid clinicians in understanding this condition better.

Time-dependent localization of high- and low-sulfated keratan sulfates in the song nuclei of developing zebra finches.

Keratan sulfate proteoglycans (KSPGs) and chondroitin sulfate proteoglycans (CSPGs) consist of a protein core with covalently attached glycosaminoglycan side chain. Although CSPGs are known to regulate the end of the critical period, the role of KSPGs in brain development remains unclear. Young male zebra finches memorise song templates during development. The brain regions that are responsible for song learning, known as song nuclei, are recognized as a suitable model for the study of brain development. To understand the potential role of KSPGs, here we examined the localization of KSs with different degrees of sulfation in the brain of developing male zebra finches. Exclusively in the song nuclei, an increase in expression of 5-D-4-positive (5-D-4(+)) high-sulfated KS started after hatching, and reached a plateau at the end of the sensory period, during which the young bird listens to and memorises the song of an adult tutor. By contrast, weak and ubiquitous expression of BCD-4(+) low-sulfated KS remained unchanged until the end of the sensory period, and first increased in the song nuclei at the end of the sensorimotor period, during which the young bird produces plastic songs. Immunoblot analysis showed that phosphacan was a common core protein of 5-D-4(+) KS and BCD-4(+) KS. Finally, we confirmed that the sulfotransferase responsible for the synthesis of high-sulfated KS was exclusively localised in the song nuclei. Our observations suggest that time-dependent localization of KSPGs with different sulfation patterns in the song nuclei may underlie song learning in developing male zebra finches.

Relationship between Corneal Guttae and Quality of Vision in Patients with Mild Fuchs' Endothelial Corneal Dystrophy.

PURPOSE: To investigate the effect of the severity of corneal guttae on quality of vision (QOV) in patients with mild Fuchs' endothelial corneal dystrophy (FECD). DESIGN: Cross-sectional study. PARTICIPANTS: Twenty-three eyes of 14 patients with mild FECD without corneal edema on slit-lamp examination (5 pseudophakic eyes and 18 phakic eyes with mild lens opacity; grade 1.0-2.0 nuclear opalescence, grade 1.0-2.0 nuclear color, grade 1.0 cortical cataract, and grade 1.0 posterior subcapsular cataract on the Lens Opacities Classification System, version III). METHODS: The area ratio of the corneal guttae (ARCG) in the endothelial cells was measured by multifocal specular microscopy. The QOV parameters, that is, corrected distance visual acuity (CDVA), letter contrast sensitivity (LCS), and intraocular straylight, also were measured. The correlations were assessed between the ARCG and QOV parameters and between the straylight and CDVA and LCS. MAIN OUTCOME MEASURES: The ARCG, logarithm of the minimum angle of resolution CDVA, LCS, and straylight. RESULTS: Univariate analysis showed that the ARCG was correlated significantly with the CDVA, LCS, and straylight (R(2) = 0.41, P = 0.001; R(2) = 0.55, P = 0.001; and R(2) = 0.39, P = 0.002, respectively). Univariate analysis also showed that straylight was correlated significantly with the CDVA and LCS (R(2) = 0.47, P = 0.001 and R(2) = 0.41, P = 0.001, respectively). CONCLUSIONS: Corneal guttae without edema caused the QOV to deteriorate in eyes with FECD. Patients with higher straylight had worse CDVA or LCS. Intraocular forward light scatter caused by corneal guttae may result in visual disturbances. Quantification of corneal guttae can be useful to evaluate the effect of guttae on the QOV and determine the surgical indications of endothelial keratoplasty for eyes with mild FECD.

Air pressure-induced iridocornea contact in a patient with primary angle closure observed with a dynamic Scheimpflug analyzer.

PURPOSE: To report air pressure-induced corneal deformation and iridocornea contact in eyes with primary angle closure (PAC) during intraocular pressure (IOP) measurement performed using a novel noncontact tonometer. METHODS: A single case report. RESULTS: We report a patient with bilateral angle closure. One eye had acute PAC and the other had PAC. The latter was evaluated by the movements of the cornea and iris during IOP measurement using a noncontact tonometer. During the examination, the corneal endothelium and the iris came into contact at the mid-peripheral pupillary area in the left eye with PAC during the corneal reaction to an air puff. In contrast, the corneal endothelium in the pupillary area did not come into contact with the iris. CONCLUSIONS: Although we observed only 1 case and there could be limitations in its interpretation, IOP measurements using a noncontact tonometer may create mechanical stress on the corneal endothelium in eyes with PAC with a very shallow anterior chamber.

A wireless neural recording system with a precision motorized microdrive for freely behaving animals.

The brain is composed of many different types of neurons. Therefore, analysis of brain activity with single-cell resolution could provide fundamental insights into brain mechanisms. However, the electrical signal of an individual neuron is very small, and precise isolation of single neuronal activity from moving subjects is still challenging. To measure single-unit signals in actively behaving states, establishment of technologies that enable fine control of electrode positioning and strict spike sorting is essential. To further apply such a single-cell recording approach to small brain areas in naturally behaving animals in large spaces or during social interaction, we developed a compact wireless recording system with a motorized microdrive. Wireless control of electrode placement facilitates the exploration of single neuronal activity without affecting animal behaviors. Because the system is equipped with a newly developed data-encoding program, the recorded data are readily compressed almost to theoretical limits and securely transmitted to a host computer. Brain activity can thereby be stably monitored in real time and further analyzed using online or offline spike sorting. Our wireless recording approach using a precision motorized microdrive will become a powerful tool for studying brain mechanisms underlying natural or social behaviors.

Corneal biomechanical properties in 3 corneal transplantation techniques with a dynamic Scheimpflug analyzer.

PURPOSE: To compare the corneal biomechanical properties of eyes that have undergone penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This case-control study comprised 20 post-PK eyes, 14 post-DALK eyes, 15 post-DSAEK eyes, and 50 normal control eyes. A dynamic Scheimpflug analyzer (the Corvis ST) was used to evaluate the corneal biomechanical properties including deformation amplitude (DA) and radius at the highest concavity (R hc). RESULTS: In post-PK eyes, the mean DA was 1.20 ± 0.13 mm, which was significantly higher than those of the control eyes (1.07 ± 0.09) and the post-DSAEK eyes (1.08 ± 0.12). The DA (1.18 ± 0.18) in the post-DALK eyes was significantly higher than in the control eyes. The R hc in the post-PK (6.34 ± 0.37 mm), -DALK (6.04 ± 1.22), and -DSAEK (6.44 ± 0.58) eyes was significantly smaller than in the control eyes (7.57 ± 0.78). CONCLUSIONS: The dynamic Scheimpflug analyzer provides a method to obtain new biomechanical information on the cornea such as the DA and R hc, and these parameters differed among eyes that had undergone 3 different types of corneal surgery. Abnormalities in these parameters after the different corneal transplantation techniques may indicate larger deviations in the stress-strain reaction of the cornea and more uncertainty in the intraocular pressure measurements than in normal eyes.

Quantitative regional differences in corneal endothelial abnormalities in the central and peripheral zones in Fuchs' endothelial corneal dystrophy.

PURPOSE: To quantitate the regional corneal differences in endothelial abnormalities in Fuchs' endothelial corneal dystrophy at multiple sites, including the peripheral zone. METHODS: Forty-one eyes of 23 patients with Fuchs' endothelial corneal dystrophy were studied at Osaka University Hospital. The sizes of the areas of degeneration resulting from guttae were measured using a new noncontact specular microscope in the central cornea, the paracentral zone 0.6 mm from the center, and the peripheral zone 3.7 mm peripheral to the center. RESULTS: The percentages of the images covered by the abnormal areas were 71% ± 36% in the center, 68% ± 35% in the paracentral zone, and 33% ± 36% in the peripheral zone. The values in the peripheral zone were significantly (P < 0.001) smaller than in the center and paracentral zones. The percentage of the abnormal area in the peripheral zone was correlated significantly (P < 0.001, R(2) = 0.452) with the disease grade in advanced cases, whereas those in the center or paracentral zones were not. Among the areas of the peripheral zone, the abnormal inferotemporal areas were significantly (P < 0.001) larger than superonasally. CONCLUSIONS: In Fuchs' endothelial corneal dystrophy, the corneal endothelium is damaged more severely in the center and paracentral zones than in the peripheral zone, and peripheral measurement can objectively grade the disease. In the peripheral zones, the inferotemporal endothelium is damaged more severely. These findings might provide a new understanding of the disease mechanisms.

Rigid gas-permeable contact lens-assisted cataract surgery in patients with severe keratoconus.

We describe rigid gas-permeable (RGP) contact lens-assisted cataract surgery in patients with severe keratoconus. During cataract surgery in cases with severe keratoconus, the intraocular images are distorted and visual perspective is lost because of irregular corneal astigmatism. Poor visibility can lead to complications, including posterior capsule rupture and corneal endothelial cell damage. To overcome these problems, an RGP contact lens was placed on the cornea in 2 cases. The image distortion decreased markedly, and the visual perspective improved. Intraocular manipulations such as irrigation/aspiration were performed safely. Improvement in transillumination led to good visualization of the anterior and posterior capsules. No intraoperative or postoperative complications developed in either case. This technique provided excellent visualization during cataract surgery in patients with severe keratoconus.

Effect of instillation of eyedrops for dry eye on optical quality.

PURPOSE: To investigate the effects of viscosity and suspensibility of eyedrops for dry eye by evaluating an eyedrop with one of the solutions or no solution (0.3% sodium hyaluronate ophthalmic solution, 3% diquafosol ophthalmic solution, and 2% rebamipide ophthalmic suspension) on ocular higher-order aberrations (HOAs) and forward light scatter. METHODS: We evaluated ocular HOAs and forward light scatter before and 1, 5, and 10 minutes after instillation of three eyedrops for dry eye in 15 healthy subjects. Saline served as the control. The HOAs were measured for a 4-mm pupil using a wavefront sensor. The obtained aberration data were analyzed in the central 4-mm diameter for total HOAs up to the sixth-order Zernike polynomials. Forward light scatter was quantified with a straylight meter. RESULTS: A significant increase was seen in the HOAs 1 minute after instillation of the three eyedrops for dry eye; the HOAs recovered to the baseline level thereafter. When 0.3% sodium hyaluronate was compared with 2% rebamipide and 3% diquafosol, the HOAs increased significantly (P < 0.01 for both comparisons) immediately after instillation. A significant increase in forward light scatter occurred 1 minute after instillation of rebamipide suspension and returned to the preinstillation level 5 minutes after instillation. No significant changes in forward light scatter occurred after instillation of 3% diquafosol or 0.3% sodium hyaluronate. CONCLUSIONS: Quantitative serial measurement of HOAs and forward light scatter showed that the temporal reduction in optical quality may be attributed mainly to increased HOAs after instillation of highly viscous 0.3% sodium hyaluronate ophthalmic solution and to increased forward light scatter after instillation of 2% rebamipide ophthalmic suspension in healthy subjects.

Neural coding of syntactic structure in learned vocalizations in the songbird.

Although vocal signals including human languages are composed of a finite number of acoustic elements, complex and diverse vocal patterns can be created from combinations of these elements, linked together by syntactic rules. To enable such syntactic vocal behaviors, neural systems must extract the sequence patterns from auditory information and establish syntactic rules to generate motor commands for vocal organs. However, the neural basis of syntactic processing of learned vocal signals remains largely unknown. Here we report that the basal ganglia projecting premotor neurons (HVC(X) neurons) in Bengalese finches represent syntactic rules that generate variable song sequences. When vocalizing an alternative transition segment between song elements called syllables, sparse burst spikes of HVC(X) neurons code the identity of a specific syllable type or a specific transition direction among the alternative trajectories. When vocalizing a variable repetition sequence of the same syllable, HVC(X) neurons not only signal the initiation and termination of the repetition sequence but also indicate the progress and state-of-completeness of the repetition. These different types of syntactic information are frequently integrated within the activity of single HVC(X) neurons, suggesting that syntactic attributes of the individual neurons are not programmed as a basic cellular subtype in advance but acquired in the course of vocal learning and maturation. Furthermore, some auditory-vocal mirroring type HVC(X) neurons display transition selectivity in the auditory phase, much as they do in the vocal phase, suggesting that these songbirds may extract syntactic rules from auditory experience and apply them to form their own vocal behaviors.