Search

Non-invasive imaging plays a crucial role in diagnosing and studying eye diseases. However, existing photoacoustic ophthalmoscopy (PAOM) techniques in mice have limitations due to handling restrictions, suboptimal optical properties, limited availability of light sources, and permissible light fluence at the retina. This study introduces an innovative approach that utilizes Rose Bengal, a contrast agent, to enhance PAOM contrast. This enables visualization of deeper structures, such as the choroidal vasculature and sclera in the mouse eye, using visible light. The integration of near-infrared-II (NIR-II) optical coherence tomography provides additional tissue contrast and insights into potential NIR-II PAOM capabilities. To optimize imaging, we developed a cost-effective 3D printable mouse eye phantom and a fully 3D printable tip/tilt mouse platform. This solution elevates PAOM to a user-friendly technology, which can be used to address pressing research questions concerning several ocular diseases, such as myopia, glaucoma, and/or age-related macular degeneration in the future. [ABSTRACT FROM AUTHOR]

PurposeTo quantify the biometric changes of ocular dimensions with mechanical elevation of intraocular pressure (IOP) in vivo, to get a better understanding of the elastic properties of the human ocular structures that may play a role in the pathogenesis of various diseases such as myopia or glaucoma.MethodsChanges in IOP were induced by a suction cup in 18 eyes under cycloplegia. Axial eye length (AEL) and anterior chamber depth (ACD) were measured with non-invasive laser interferometry during elevation of the IOP 10 and 20 mmHg over baseline values and after a 10-min resting period.ResultsIOP elevation of 10 and 20 mmHg respectively caused a significant increase of AEL of 23 μm (95% confidence interval: 14–34 μm) and 39 μm (confidence interval (CI): 28–51 μm). After mechanical oculopression, which resulted in an IOP reduction of –5.1 mmHg (CI: −6.3 to −4.0 mmHg) vsbaseline, a significant shortening of −7 μm (CI: −13 to 0 μm) was observed. The change in AEL correlated with the change in IOP (r=0.66, P=0.005). Furthermore, a significant increase in ACD of 30 μm (CI: 24–36 μm) was detected with IOP reduction after oculopression, but no change was seen during IOP elevation.ConclusionsBiometric changes of the human eye as a response to IOP changes were assessed in vivo. The correlation between change in AEL and IOP found emphasizes the need of in vivoocular rigidity measurements in the human eye.Eye (2008) 22, 657–661; doi:10.1038/sj.eye.6702709; published online 19 January 2007 [ABSTRACT FROM AUTHOR]

In recent years, superluminescent diodes (SLDs) have gained increasing importance as light sources for partial coherence interferometry and optical coherence tomography. The requirements of SLDs are high spatial coherence, low temporal coherence, and, for some applications, high power. Since there might be a trade-off between these properties we built an instrument for measuring the spatial coherence of SLDs. This instrument consists of a hybrid bulk optic-fibre optic Mach-Zehnder interferometer. The special advantages of the instrument are the ability to measure the spatial coherence between arbitrary points within the light beam and to observe directly the measurement points within the beam which facilitates the alignment. We used this instrument to evaluate the spatial coherence of several commercially available SLDs. As expected, a single mode fibre pigtailed SLD shows the best spatial coherence. If free-space emitting SLDs are considered, those with a more complicated chip structure have a somewhat poorer spatial coherence, however, their temporal coherence is considerably better than that of a SLD which is only antireflection coated. [ABSTRACT FROM AUTHOR]

We present a new OCT technique which renders the transversal resolution depth independent. This is achieved by an optical setup which shifts the focus of the beam illuminating the object through the object depth without changing the path length in the corresponding interferometer arm. Therefore, the coherence gate remains at the beam focus without any readjustment of the reference arm. Depth resolution was tested with the help of microscopy coverplates and transversal resolution was tested with the help of Ronchi rulings. Resolution was 100linesmm[sup -1] over an object depth of 430µm. For a first demonstration of the properties of this dynamic coherent focus scheme in a biologic system a section of a human cornea was used. We expect that this technique can further be improved to obtain transversal resolution down to the 1-µm range. [ABSTRACT FROM AUTHOR]

Purpose This prospective study aimed to investigate the effect of myopic defocus on choroidal thickness in emmetropic, in moderately myopic and in highly myopic subjects. Methods A 3-dimensional spectral domain-optical coherence tomography (SD-OCT) system that operates at a wavelength of 1060 nm was used to measure choroidal thickness in the 9 sections according to the 'early treatment diabetic retinopathy study' (ETDRS) grid before and after a period of 60 minutes of defocus with a +3.00 Dioptre (D) lens in one eye of 15 emmetropic (spherical equivalent-SE: −0.75 to +0.75D; group A), 15 moderately myopic (SE: −6.00 to −2.50D; group B) and 15 highly myopic subjects (SE: ≥−6.25D; group C). Results Choroidal thickness was in all ETDRS fields significantly thicker in emmetropic than in moderately and in highly myopic subjects. Central field choroidal thickness before and after defocus was in group A 322 ± 59 μm and 321 ± 57 μm, in group B 259 ± 71 μm and 258 ± 65 µm and in group C 237 ± 64 µm and 237 ±65 µm. Choroidal thickness did not differ from before to after defocus in the central ETDRS field (group A: −1 ± 12 µm, p = 0.710; group B: −1 ± 8 µm, p = 0.660; group C: 0 ± 6 µm; p = 0.995; paired t-test) and these differences did not differ significantly between the groups (p=0.940, ANOVA). In the peripheral ETDRS fields choroidal thickness changes from before to after defocus were neither found to be significant within the groups (p > 0.05, paired t-test) nor between the groups (p > 0.05, ANOVA). Conclusions Myopic defocus does not influence the choroidal thickness in emmetropic, moderately myopic and in highly myopic subjects. [ABSTRACT FROM AUTHOR]