Flap characteristics, predictability, and safety of the Ziemer FEMTO LDV femtosecond laser with the disposable suction ring for LASIK.

AIMS: The outcomes of laser-assisted in situ keratomileusis (LASIK) operations performed with the Classic FEMTO LDV femtosecond laser using the plastic single-use suction ring (Ziemer Ophthalmic Systems) and the Allegretto Wave Concerto 500 Hz excimer laser (Wavelight AG) are presented in terms of accuracy, predictability, and safety of the operation. METHODS: A FEMTO LDV plastic suction ring was used for flap creation in 342 eyes of 179 patients. The intended flap thickness was 90 µm. The size of the suction ring varied from 9.0 to 10.0 mm. Flap dimensions were measured and correlated to preoperative characteristics. RESULTS: Mean flap thickness was very constant, 89.6 ± 2.0 µm (range 84-97). In 163 bilateral operations, the second flap was 1.1 µm thinner than the one cut first (P<0.0001). Mean flap diameter was 9.4 ± 0.2 mm (range 8.1-9.9). Mean hinge length was 3.9 ± 0.2 mm (range 3.0-4.2). In hyperopic eyes, flap thickness correlated negatively with keratometric power K1 and flap diameter. In hyperopic eyes, flap diameter correlated positively with spherical equivalent refraction and with keratometric power K1 as well as hinge length both in myopic and hyperopic eyes. Complications were reported in 12 (3.5%) eyes. Complications were very mild and none of them prevented further refractive laser treatment. Two Snellen lines of corrected distance visual acuity were lost in one (0.3%) eye. CONCLUSION: The FEMTO LDV plastic single-use suction rings yielded accurate and reproducible flaps and were safe for the creation of thin corneal flaps.

Impacts of changes in water quality on recreation behavior and benefits in Finland.

The implementation of the European Union Water Framework Directive (WFD) requires nationally generalizable estimates of the benefits of protecting inland and coastal waters. As an alternative to benefit transfers and meta-analyses, we utilize national recreation inventory data combined with water quality data to model recreation participation and estimate the benefits of water quality improvements. Using hurdle models, we analyze the association of water clarity in individuals' home municipalities with the three most common water recreation activities--swimming, fishing and boating. The results show no effect on boating, but improved water clarity would increase the frequency of close-to-home swimming and fishing, as well as the number of fishers. Furthermore, to value the potential benefits of the WFD, we estimate the consumer surplus of a water recreation day using a travel cost approach. A water policy scenario with a 1-m improvement in water clarity for both inland and coastal waters indicates that the consumer surplus would increase 6% for swimmers and 15% for fishers. In contrast to previously estimated abatement costs to improve water quality, net benefits could turn out to be positive. Our study is a promising example of applying existing national recreation inventory data to estimate the benefits of water quality improvements for the purposes of the WFD.

In vitro biocompatibility of degradable biopolymers in cell line cultures from various ocular tissues: direct contact studies.

Synthetic biodegradable polymers have many potential therapeutic applications. In ophthalmology, biodegradable polymers have been used as viscoelastic agents and surgical implants. Other potential applications include controlled release of drugs and growth factors, gene therapy, and tissue engineering. In the present study, in vitro biocompatibility of three biodegradable polymers, 50:50 PDLGA, 85:15 PDLGA, and Inion GTR membrane was evaluated in comparison to tissue culture polystyrene by investigating cell proliferation and potential acute toxicity by the WST-1 cytotoxicity/cell proliferation test, the ATP test, and the lactate dehydrogenase (LDH) test. Evaluations were conducted with cell line cultures from various ocular tissues, human corneal epithelial cells (HCE), rabbit stromal fibroblasts (SIRC), bovine corneal endothelial cells (BCE), human conjunctival epithelial cells (IOBA-NHC), and human retinal pigment epithelial cells (ARPE-19) by direct contact studies by plating the cells on the polymer film specimens in 96-wells. The proliferation results show that cell lines from various ocular tissues attached and grew on PDLGA 50:50, PDLGA 85:15, and Inion GTR membrane. Cytotoxicity experiments with the LDH and ATP tests showed no or extremely slight toxic adverse effects. These polymers have potential to be used as scaffolds in cell transplantation devices or as surgical implants.

Evaluation of the cytotoxicity of selected systemic and intravitreally dosed drugs in the cultures of human retinal pigment epithelial cell line and of pig primary retinal pigment epithelial cells.

The cytotoxicity of the selected systemic and intravitreally dosed drugs tamoxifen, toremifene, chloroquine, 5-fluorouracil, gentamicin and ganciclovir was studied in retinal pigment epithelium (RPE) in vitro. The cytotoxicity was assayed in the human RPE cell line D407 and the pig RPE cell culture using the WST-1 test, which is an assay of cell proliferation and viability. The effects of experimental conditions on the WST-1 test (cell density, serum content in the culture medium, the exposure time) were evaluated. The EC50 values in tamoxifen-treated D407 cells ranged between 6.7 and 8.9 micromol/l, and in pig RPE cells between 10.1 and 12.2 micromol/l, depending on the cell density used. The corresponding values for toremifene were 7.4 to 11.1 micromol/l in D407 cells and 10.0 to 11.6 micromol/l in pig RPE cells. In chloroquine-treated cells, the EC50 values were 110.0 micromol/l for D407 cells and 58.4 micromol/l for pig RPE cells. Gentamicin and ganciclovir did not show any toxicity in micromolar concentrations. The exposure time was a significant factor, especially when the drug did not induce cell death, but was antiproliferative (5-fluorouracil). Serum protected the cells from the toxic effects of the drugs. Both cell cultures were most sensitive to tamoxifen and toremifene, and next to chloroquine. The drug toxicities obtained in the present study were quite similar in both cell types; that is, the pig RPE cells and the human D 407 cell line, despite the differences in, for example, the growth rate and melanin contents of the cell types. Owing to the homeostatic functions important for the whole neuroretina, RPE is an interesting in vitro model for the evaluation of retinal toxicity, but, in addition to the WST-1 test, more specific tests and markers based on the homeostatic functions of the RPE are needed.

Effects of ethyl alcohol on hypothalamic affective defense in the cat.

Hypothalamic stimulation was used to elicit affective defense in the cat. The behavior was recorded by direct observation and a video tape recorder, and different components thereof were evaluated on a rating scale. The effect of ethyl alcohol, 0.25, 0.5, 1.0 and 1.5 g/kg body weight, on behavior was studied. Doses of 0.25 and 0.5 g/kg had no clear effect; 1.0 and 1.5 g/kg depressed the majority of the rated components.

Innervation of the rat Harderian gland by adrenergic and cholinergic nerve fibres.

The innervation of the rat Harderian gland was studied using histochemical methods for catecholamines and acetylcholinesterase (AChE). Selective denervations were performed to investigate the neural connections of this gland with various ganglia. Light microscopically the AChE-positive nerves seemed to run as thick bundles in the intertubular connective tissue. These bundles sent finer branches around the acini. The blood vessels, localized in the connective tissue septa, were surrounded by a dense plexus of AChE-containing fibres. By electron microscopy, the AChE-positive fibres were seen to terminate near the myoepithelial cells surrounding secretory cells. These fibres were also observed in contact with the blood vessels and occasionally close to the secretory cells. Fluorescent adrenergic nerves surrounded the blood vessels. Some fibres were also observed in the interlobular tissue. All the AChE-containing nerves degenerated after cutting the zygomatic nerve. On the other hand, removal of the ciliary ganglion or the superior cervical ganglion, or stereotactic coagulation of the ophthalmic nerve did not affect these nerves. The fluorescent adrenergic fibres disappeared following both removal of the superior cervical ganglion and coagulation of the ophthalmic nerve. These fibres were intact after removal of the ciliary ganglion.

Effects of denervations on the acetylcholinesterase-containing and fluorescent nerves of the rat iris.

The thiocholine method for the demonstration of AChE-containing fibres and the formaldehyde-induced fluorescence technique for the visualization of adrenergic fibres were employed to study the innervation of the albino rat iris. The following denervations were performed in order to verify the origins of different nerve types: (1) extirpation of the ciliary ganglion, (2) extirpation of the superior cervical ganglion, (3) stereotactic coagulation of the ophthalmic division of the trigeminal nerve, and (4) all possible combinations of the above-mentioned procedures. The denervations disclosed three main types of AChE-containing nerves in the iris: (1) nerve fibres degenerating after ciliary ganglionectomy, (2) thick nerve bundles in the dilator region disappearing after trigeminal neurotomy, and (3) fibres remaining intact after any type of denervation. Cervical sympathectomy had no effect on AChE-positive fibres. Under electron microscope AChE activity could be seen in the axolemma both in unmyelinated and in myelinated fibres. All fluorescent fibres vanished after ipsilateral cervical sympathectomy. Most of these fibres also disappeared after trigeminal neurotomy and the remaining fibres degenerated after subsequent ciliary ganglionectomy. On the basis of the present findings, the following conclusions can be drawn: (1) Most AChE-containing fibres of the rat iris originate in the ciliary ganglion. (2) The majority of the myelinated sensory fibres of the rat iris also contain AChE. (3) There is no AChE in the adrenergic fibres of the rat iris. (4) All adrenergic fibres of the rat iris originate in the ipsilateral superior cervical ganglion, and (5) these fibres enter the iris along with both the long and short ciliary nerves.

Ethyl alcohol and defence behavior in the cat.

The effects of graded doses of ethyl alcohol on defence behaviour were studied in nine cats: 0.25 g/kg of body weight had a slight but not significant excitatory effect, 0.5 and 1.0 g/kg had no effect and 1.5 g/kg significantly depressed some behavior components. When taking the scores for all the manifestations combined as an index of gross behaviour, 0.25 significantly intensified, 0.5 and 1.0 did not change and 1.5 g alcohol/kg significantly depressed defence. These results are consistent with the expected effects of alcohol on physiological functions in general.

Ultrastructural changes of the capillaries of the cat iris in experimental neuroparalytic keratitis.

In order to study the morphological basis of the increased permeability of the capillaries of the iris in neuroparalytic keratitis the ophthalmic division of the trigeminal nerve in the cat was denervated using a stereotactic method. The homolateral iris was studied by electron microscopy three days after denervation. Abnormally large pinocytotic vacuoles were observed in the endothelial cells of the iris capillaries and the intercellular junctions of the endothelial cells showed widened inter-cellular space and macula occludens. These ultrastructural changes may explain the protein leakage into the anterior chamber in neuroparalytic keratitis.