Publications

It has been hypothesized that synaptic pruning precedes retinal ganglion cell degeneration in glaucoma, causing early dysfunction to retinal ganglion cells. To begin to assess this, we studied the excitatory synaptic inputs to individual ganglion cells in normal mouse retinas and in retinas with ganglion cell degeneration from glaucoma (DBA/2J), or following an optic nerve crush. Excitatory synapses were labeled by AAV2-mediated transfection of ganglion cells with PSD-95-GFP. After both insults the linear density of synaptic inputs to ganglion cells decreased. In parallel, the dendritic arbors lost complexity. We did not observe any cells that had lost dendritic synaptic input while preserving a normal or near-normal morphology. Within the temporal limits of these observations, dendritic remodeling and synapse pruning thus appear to occur near-simultaneously.

Purpose: To analyze the age dependence of the longitudinal modulus of the crystalline lens in vivo using Brillouin scattering data in healthy subjects. Methods: Brillouin scans were performed along the crystalline lens in 56 eyes from 30 healthy subjects aged from 19 to 63 years. Longitudinal elastic modulus was acquired along the sagittal axis of the lens with a transverse and axial resolution of 4 and 60 μm, respectively. The relative lens stiffness was computed, and correlations with age were analyzed. Results: Brillouin axial profiles revealed nonuniform longitudinal modulus within the lens, increasing from a softer periphery toward a stiffer central plateau at all ages. The longitudinal modulus at the central plateau showed no age dependence in a range of 19 to 45 years and a slight decrease with age from 45 to 63 years. A significant intersubject variability was observed in an age-matched analysis. Importantly, the extent of the central stiff plateau region increased steadily over age from 19 to 63 years. The slope of change in Brillouin modulus in the peripheral regions were nearly age-invariant. Conclusions: The adult human lens showed no measurable age-related increase in the peak longitudinal modulus. The expansion of the stiff central region of the lens is likely to be the major contributing factor to age-related lens stiffening. Brillouin microscopy may be useful in characterizing the crystalline lens for the optimization of surgical or pharmacological treatments aimed at restoring accommodative power.

PURPOSE: Identify a reproducible measure of axial globe position (AGP) for multicenter studies on patients with thyroid eye disease (TED). METHODS: This is a prospective, international, multicenter, observational study in which 3 types of AGP evaluation were examined: radiologic, clinical, and photographic. In this study, CT was the modality to which all other methods were compared. CT AGP was measured from an orthogonal line between the anterior lateral orbital rims to the cornea. All CT measurements were made at a single institution by 3 individual clinicians. Clinical evaluation was performed with exophthalmometry. Three clinicians from each clinical site assessed AGP with 3 different exophthalmometers and horizontal palpebral width using a ruler. Each physician made 3 separate measurements with each type of exophthalmometer not in succession. All photographic measurements were made at a single institution. AGP was measured from lateral photographs in which a standard marker was placed at the anterior lateral orbital rim. Horizontal and vertical palpebral fissure were measured from frontal photographs. Three trained readers measured 3 separate times not in succession. Exophthalmometry and photography method validity was assessed by agreement with CT (mean differences calculation, intraclass correlation coefficients [ICCs], Bland-Altman figures). Correlation between palpebral fissure and CT AGP was assessed with Pearson correlation. Intraclinician and interclinician reliability was evaluated using ICCs. RESULTS: Sixty-eight patients from 7 centers participated. CT mean AGP was 21.37 mm (15.96-28.90 mm) right and 21.22 mm (15.87-28.70 mm) left (ICC 0.996 and 0.995). Exophthalmometry AGP fell between 18 mm and 25 mm. Intraclinician agreement across exophthalmometers was ideal (ICC 0.948-0.983). Agreement between clinicians was greater than 0.85 for all upright exophthalmometry measurements. Photographic mean AGP was 20.47 mm (10.92-30.88 mm) right and 20.30 mm (8.61-28.72 mm) left. Intrareader and interreader agreement was ideal (ICC 0.991-0.989). All exophthalmometers' mean differences from CT ranged between -0.06 mm (±1.36 mm) and 0.54 mm (±1.61 mm); 95% confidence interval fell within 1 mm. Magnitude of AGP did not affect exophthalmometry validity. Oculus best estimated CT AGP but differences from other exophthalmometers were not clinically meaningful in upright measurements. Photographic AGP (right ICC = 0.575, left ICC = 0.355) and palpebral fissure do not agree with CT. CONCLUSIONS: Upright clinical exophthalmometry accurately estimates CT AGP in TED. AGP measurement was reliably reproduced by the same clinician and between clinicians at multiple institutions using the protocol in this study. These findings allow reliable measurement of AGP that will be of considerable value in future outcome studies.

PURPOSE: Corneal neuropathy is a recently described disease process that is not well understood and is likely underdiagnosed as a result. This is the first reported case of an acquired corneal neuropathy associated with malposition of an Ex-PRESS shunt. METHODS: A single case report. RESULTS: We report the case of a 50-year-old man with a history of multiple procedures for glaucoma who subsequently developed photoallodynia and corneal neuropathy in association with malposition of an Ex-PRESS shunt in the peripheral cornea. Laser confocal microscopy (HRT3/RCM) of the cornea showed the presence of neuromas, decreased nerve density, and a significant increase of dendritiform immune cells consistent with our diagnosis. Initial treatment with steroid pulse therapy did not result in decreased inflammation or symptomatic improvement leading to surgical explantation of the shunt. One month after surgery, there was noticeable improvement in the patient's pain and photoallodynia (approximately 40%) as well as the abnormalities seen on confocal microscopy. CONCLUSIONS: We hypothesize that poor Ex-PRESS shunt positioning can act as a nidus for corneal inflammation, resulting in corneal neuropathy and lowering of the nociception threshold.

The ability to form biofilms in a variety of environments is a common trait of bacteria, and may represent one of the earliest defenses against predation. Biofilms are multicellular communities usually held together by a polymeric matrix, ranging from capsular material to cell lysate. In a structure that imposes diffusion limits, environmental microgradients arise to which individual bacteria adapt their physiologies, resulting in the gamut of physiological diversity. Additionally, the proximity of cells within the biofilm creates the opportunity for coordinated behaviors through cell-cell communication using diffusible signals, the most well documented being quorum sensing. Biofilms form on abiotic or biotic surfaces, and because of that are associated with a large proportion of human infections. Biofilm formation imposes a limitation on the uses and design of ocular devices, such as intraocular lenses, posterior contact lenses, scleral buckles, conjunctival plugs, lacrimal intubation devices and orbital implants. In the absence of abiotic materials, biofilms have been observed on the capsule, and in the corneal stroma. As the evidence for the involvement of microbial biofilms in many ocular infections has become compelling, developing new strategies to prevent their formation or to eradicate them at the site of infection, has become a priority.