Design and performance of a new ophthalmic instrument for dynamic light-scattering measurements in the human eye

A new optical instrument for in vivo dynamic light-scattering measurements in the human eye isdescribed. The instrument is based on the well-known dynamic light-scattering technique. Resultscan be obtained from the anterior as well as the posterior segment with high spatial resolution andsensitivity. This instrument allows, to our knowledge for the first time, in vivo measurements ofdynamic light scattering to be performed in the vitreous. Interesting performance is obtained usingsingle-mode optical fibers to guide the excitation and the scattered light resulting in a modular,compact system with high-beam quality and electrical insulation of the patient. The instrumentdemonstrates good safety characteristics ~the optical power impinging the patient’s eye is 36 timesbelow the maximum laser power at the cornea, recommended for intrapupil exposure by ANSIstandard!. To demonstrate the possible clinical use of this technique, in vivo measurements weremade and the results compared with the known eye pathologies

A non invasive instrument for in vivo dynamic laser light scattering measurement in the human eye

A new optical instrument for `in vivo' analysis of ocular tissue is presented. The instrument is based on the well know dynamic light scattering technique. Using optimal beam shaping the analysis can be achieved in the cornea and in the anterior chamber as well as in the lens and in the vitreous with high spatial resolution and sensitivity. In order to obtain high beam quality, to provide modularity and galvanic insulation of the instrument, monomode optical fibers are used to guide the excitation and the scattered light. Following a description of the instrument, preliminary `in-vivo' measures are discussed in order to asses the performance of the instrument in ophthalmology diagnostic

In vivo dynamic light scattering changes of the vitreous in diabetes mellitus

Purpose. Dynamic light scattering (DLS) is a well known non-invasive diagnostic tool used in the anter or segment. In this study in vivo DLS measurements of the human vitreous have been performed to detect changes during the course of diabetes mellitus both with and without diabetic retinopathy. Material and Methods. 50 diabetes mellitus patients with ocular complications varying form no diabetic retinopathy through to severe diabetic retnopathy were examined using DLS techniques. Measurements were performed at different topographical locations of the vitreous, the retrovitreal space and the retina. The results were compared to measurements of 50 normal subjects. Results. The autocorrelation function obtained from the DLS signal in the normal vitreous exhibits two peaks which correspond to the contribution from macromolecules These peaks were found to alter, either in applitude or location, during the course of diabetic retinopathy. The degree and form of these alterations was correlated to the severity of the ocular complicatons in the structures investigated. DLS measurements in the cornea exhibited similar effects to those made in the vitreous. Conclusions. DLS is capable of detecting the changes of the vitreous associated with diabetes mellitus. Moreover, due to the close correlation of the DLS results with the severity of viteo-retinal changes, DLS may serve as an important tool for the early diagnosis and monitoring of ocular complications due to diabetes mellitus

In vivo dynamic light scattering measurements in the cornea of the human eye prior to and after excimer laser refractive surgery

Purpose. Dynamic light scattering (DLS) can be used as a non-invasive optical probe for in vivo molecular diagnostics in the human eye. The purpose of this pilot study is to demonstrate the detectability of changes in the molecular structure of the human cornea after excimer laser photorefractive keratectomy (PRK) or phototherapeutic keratectomy (PTK). Material and Methods. 10 patients underwent excimer laser treatment, either for the correction of myopia (PRK) or for therapeutic reasons (PTK). DLS measurements of the corneal stroma were performed prior to and after (immediately, 1 day, 5, 10 days, 1 month, 3 months) treatment. Measurements were perfomed at different topographical locations both inside and outside the treated areas of the corneal stroma. Results. The autocorrelation function obtained from the DLS signal exhibits two peaks corresponding to the fast and slow components of the stroma. After excimer laser treatment the location as well as the amplitude of these peaks were significantly altered. These alterations did not correlate to the ablation depth during treatment nor to the pre-operative refractive error. Only minor corneal haze was observed which showed no statistically significant correlation with alterations of the peaks. No formation of corneal scars was observed in any patient. Conclusions. DLS seems to be a suitable tool for observation of the wound healing processes in the cornea after treatment by excimer laser. Due to the limited number of cases, statistically significant results are not yet available. Ongoing investigations involving a larger number of cases may reveal the power of DLS for diagnosis of abnormal healing processes

Extreme lateral lumbar disc herniation in a 12-year child: case report and review of the literature

Extreme lateral lumbar disc herniations (ELLDHs) occur more frequently among elderly patients, with a peak incidence in the sixth decade, and are rarely found in children. The patient presented is a 12-year-old boy with a 3-month history of right-sided leg pain. Computerized tomography and magnetic resonance imaging demonstrated an extreme lateral disc herniation on the right at L4–L5 with compression of the L4 nerve root. He subsequently underwent removal of extreme lateral herniated disc through an intertransverse approach under general anesthesia. At 11-month follow-up, the patient maintained resolution of preoperative symptoms and a neurological examination revealed no sensory or motor deficit. Surgical intervention may be indicated for patients with ELLDHs that fail with conservative treatment