Raman spectroscopy is a qualitative and quantitative optical technique for determining the molecular composition of matter. Improvements in spectroscopic instruments, especially the modality to detect low light level signals extended the Raman technique to biomedical applications, even in delicate structures like the eye. The purpose of this paper was to make an inventory of performed applications of Raman spectroscopy in biomedical science and especially in ophthalmology. A literature search was done using Medline, Current Contents, a patent server on the Internet, and references found in articles and patents. This search revealed a variety of Raman techniques and applications in biomedical research, and an increasing flow of articles starting in the late 1970s on Raman spectroscopy in ophthalmology. This increase in literature about Raman spectroscopy in ophthalmology feeds the expectation that this valuable technique will be introduced in the future into clinical practice.

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The purpose of this work was to obtain more quantitative knowledge about the yield of fluorescence from retinal vessels during indocyanine green angiography (ICG). The yield of fluorescence from blood was investigated for various shear rates, concentrations of ICG, and layer thicknesses. Measurements were performed in vitro on samples of human blood in a cone-plate shear chamber using frontal illumination as in scanning laser angiography. In blood and in plasma, the yield of fluorescence of ICG increased with concentration up to 0.05 and 0.1 mg/ml, respectively. At higher concentrations, the yield decreased for all layer thicknesses. For increasing layer thicknesses, both in plasma and in blood, the yield of ICG fluorescence increased nonlinearly for concentrations higher than 0.012 mg/ml. Saturation occurred for layers thicker than 200 microns in combination with ICG concentrations of 0.4 mg/ml and higher. Application of shear rates within the physiological range of the microcirculation (88/sec and 528/sec) increased the yield of fluorescence from the blood sample compared with stasis. The high transparency of blood for the excitation and emission light of ICG that was demonstrated will lead to superposition of fluorescence from superficial and deeper layers. This superposition precludes quantitative indocyanine angiography of ocular vessels.

Raman spectroscopy may offer an effective tool to non-invasively assess the local concentration of the delivered drugs within the ocular media. This technique potentially could be used to investigate the pharmacokinetics of intraocular drugs in vivo either from a releasing implant or a direct injection.

Raman spectroscopy may offer an effective tool for the noninvasive assessment of the local concentration of ganciclovir in the ocular media. This technique offers the potential to determine both the amount and the rate of the drug release from implants designed to deliver antiviral drugs locally within the eye. The availability of such data could enable the ophthalmologist to improve treatment efficacy by avoiding premature or late surgical replacement of the implants.

Corneal topography has, due to developments in refractive surgery and contact lens fitting, become a widely used diagnostic tool. Many types of topographers have been introduced, but there is some confusion on classification and subsequent principal possibilities of the various devices offered to the practitioner. The purpose of the study reported here was to make an inventory of developed devices, analyse the basic principles and create a classification based on optical principles. A literature search was done using Medline, the IBM Patent Server, and references found in articles and patents. This search resulted in a variety of descriptions that could be classified into 12 groups according to their use of light source and light-matter interaction of which four groups have representatives on the commercial market. This classification can be used by researchers and practitioners to gain insight into the possibilities of a given device in relation to the desired application.

The influence of linearly polarized argon laser irradiation (lambda = 488 nm and 514.5 nm) on the closure time of standardized open skin wounds was measured in rats. In two separate controlled experiments no acceleration of wound closure by laser irradiation was observed. In the first experiment the wounds were cleaned during the laser treatment period at 1 J/cm2. The second experiment at 4 J/cm2 was without mechanical wound cleaning. The contradictory results reported in the literature and possible influences of wavelength, energy density, and power density are discussed.

The potency of annexin V to transport Ca 2+ ions across phospholipid membranes was investigated, using large unilamellar phospholipid vesicles loaded with the Ca z+ indicator fura-2. It was demonstrated that annexin V leaves the vesicle membranes intact when added in the presence of 1 mM Ca 2+. However, if the vesicles were first incubated with aunexin V in the absence of Ca 2+, subsequent addition of Ca 2+ produced a fluorescence signal due to binding of Ca 2+ to fura-2. Centrifugation of the vesicle suspension immediately thereafter showed that this signal originated from the supernatant and not from the sedimented vesicles. Our results show that annexin V causes loss of vesicle integrity in the absence of Ca 2+, and leakage of trapped fura-2, rather than inward Ca 2+ transport. Bovine serum albumin or Ca 2+ concentrations higher than 2.5 mM also caused such fura-2 leakage. Apparently, calcium-dependent binding of annexin V to the membrane prevents aspecific membrane damage caused by this protein.Key words: Annexin V; Fura-2; Large unilamellar vesicle; Membrane damage; Calcium channel was interpreted as formation of calcium channels promoting influx of calcium into the vesicles. Ultrastructural analysis has revealed a hydrophilic pore in the annexin V molecule that could serve as an ion-selective filter [5,7,8].In view of the earlier mentioned peripheral binding and rapid desorption of annexin V, the formation of transbilayer channels of this protein seems surprising. Also, using black lipid membranes [9,10] of much larger surface area than membranes on micropipettes, we were unable to confirm calcium channel formation by annexin V in the presence of 1 mM calcium (H. Miedema, IMBS, Amsterdam, unpublished results).Here we report the investigation of membrane perturbing properties of annexin V in the LUV system as described by Berendes [6]. The obtained results show that at low calcium concentrations annexin V perturbs membranes such that they become leaky. In contrast, at higher calcium concentrations annexin V promotes membrane integrity.