Efficacy and safety of contact transscleral diode laser cyclophotocoagulation for advanced glaucoma.

BACKGROUND: This prospective study was conducted to evaluate the efficacy and safety of transscleral diode laser cyclophotocoagulation in refractory, advanced glaucoma. PATIENTS AND METHODS: One hundred eyes of 100 patients with advanced glaucoma refractory to medical treatment were consecutively treated by transscleral diode laser cyclophotocoagulation. Success was defined as a final intraocular pressure between 5 and 21 mm Hg in eyes with a visual acuity of more than hard movements, relief of pain in eyes with a visual acuity of hand movements or less including blind eyes, and reduction of carbonic anhydrase inhibitor use in all eyes. RESULTS: Ninety-three patients were followed up for 1 year after initial treatment. The overall success rate was 74.2%. Of 60 eyes with a visual acuity of more than hand movements, intraocular pressure between 5 and 21 mm Hg was achieved in 41 (68.3%) eyes. Relief of pain was achieved in 28 (84.8%) of 33 eyes. Reduction of systemic carbonic anhydrase inhibitor use was highly significant (P < 0.0001). Within 1 year, 173 laser procedures (mean, 1.9 per patient) were performed. The probability of success increased significantly (P = 0.004) with the age of the patients, from 55% for patients younger than the age of 50 years to 83% for patients older than the age of 50 years. Previous ocular surgery decreased the success probability from 95% to 68% (P = 0.02). A high success rate was achieved in inflammatory glaucoma (75%), primary open-angle glaucoma (89.5%), and neovascular glaucoma (86.7%). The results were relatively poor in traumatic glaucoma (57.1%), aphakic glaucoma (57.1%), and congenital or juvenile glaucoma (62.5%). No significant relationship between loss of visual acuity and failure of treatment (P = 0.3) could be detected. No phthisis bulbi or persistent hypotonia developed. CONCLUSIONS: Transscleral diode laser cyclophotocoagulation is an effective and safe method for the treatment of advanced, refractory glaucoma. However, repeated treatments are often necessary. Success of treatment depends on the age of patients, previous surgery, and the type of glaucoma.

Genetic and ecological divergence of a monophyletic cichlid species pair under fully sympatric conditions in Lake Ejagham, Cameroon.

Although there is mounting evidence that speciation can occur under sympatric conditions, unambiguous examples from nature are rare and it is almost always possible to propose alternative allopatric or parapatric scenarios. To identify an unequivocal case of sympatric speciation it is, therefore, necessary to analyse natural settings where recent monophyletic species flocks have evolved within a small and confined spatial range. We have studied such a case with a cichlid species flock that comprises five Tilapia forms endemic to a tiny lake (Lake Ejagham with a surface area of approximately 0.49 km2) in Western Cameroon. Analysis of mitochondrial D-Loop sequences shows that the flock is very young (approximately 10(4) years) and has originated from an adjacent riverine founder population. We have focused our study on a particular pair of forms within the lake that currently appears to be in the process of speciation. This pair is characterized by an unique breeding colouration and specific morphological aspects, which can serve as synapomorphic characters to prove monophyly. It has differentiated into a large inshore and a small pelagic form, apparently as a response to differential utilization of food resources. Still, breeding and brood care occurs in overlapping areas, both in time and space. Analysis of nuclear gene flow on the basis of microsatellite polymorphisms shows a highly restricted gene flow between the forms, suggesting reproductive isolation between them. This reproductive isolation is apparently achieved by size assortative mating, although occasional mixed pairs can be observed. Our findings are congruent with recent theoretical models for sympatric speciation, which show that differential ecological adaptations in combination with assortative mating could easily lead to speciation in sympatry.

Phylogeography of the bullhead Cottus gobio (Pisces: Teleostei: Cottidae) suggests a pre-pleistocene origin of the major central European populations.

The bullhead Cottus gobio is a small, bottom-dwelling fish consisting of populations that have not been subject to transplantations or artificial stocking. It is therefore an ideal model species for studying the colonization history of central European freshwater systems, in particular with respect to the possible influences of the Pleistocene glaciation cycles. We sampled Cottus populations across most of its distribution range, with a special emphasis on southern Germany where the major European drainage systems are in closest contact. Mitochondrial D-loop sequencing of more than 400 specimens and phylogenetic network analysis allowed us to draw a detailed picture of the colonization of Europe by C. gobio. Moreover, the molecular distances between the haplotypes enabled us to infer an approximate time frame for the origin of the various populations. The founder population of C. gobio stems apparently from the Paratethys and invaded Europe in the Pliocene. From there, the first colonization into central Europe occurred via the ancient lower Danube, with a separate colonization of the eastern European territories. During the late Pliocene, one of the central European populations must have reached the North Sea in a second step after which it then started to colonize the Atlantic drainages via coastal lines. Accordingly, we found very distinct populations in the upper and lower Rhine, which can be explained by the fact that the lower Rhine was disconnected from the upper Rhine until approximately 1 million years ago (Ma). More closely related, but still distinct, populations were found in the Elbe, the Main and the upper Danube, all presumably of Pleistocene origin. Intriguingly, they have largely maintained their population identity, despite the strong disturbance caused by the glaciation cycles in these areas. On the other hand, a mixing of populations during postglacial recolonization could be detected in the lower Rhine and its tributaries. However, the general pattern that emerges from our analysis suggests that the glaciation cycles did not have a major impact on the general population structure of C. gobio in central Europe.

A comparison of two indirect methods for estimating average levels of gene flow using microsatellite data.

We compare the performance of Nm estimates based on FST and RST obtained from microsatellite data using simulations of the stepwise mutation model with range constraints in allele size classes. The results of the simulations suggest that the use of microsatellite loci can lead to serious overestimations of Nm, particularly when population sizes are large (N > 5000) and range constraints are high (K < 20). The simulations also indicate that, when population sizes are small (N /= 50) and many loci (nl >/= 20), RST performs better than FST for most of the parameter space. However, FST-based estimates are always better than RST when sample sizes are moderate or small (ns

Holmium:YAG thermokeratoplasty: treatment parameters for astigmatism induction based upon spherical enucleated human eyes.

BACKGROUND: The refractive outcome of thermokeratoplasty for astigmatism correction depends upon the optical zone diameter (OZD) and coagulation angle (CA; distance between two coagulation spots around the flat meridian). METHODS: Astigmatism was induced in 36 spherical human eye-bank eyes (Ho:YAG laser, 15 Hz, 20 mJ/pulse, 25 pulses per coagulation spot) with different OZDs and CAs. Thirty eyes received free-hand laser application (marked positions). Six eyes were treated using a suction mask, providing a constant OZD of 8.1 mm and an angle of 22.5 degrees between the laser spots. To compare the results, silicone replicas of the eyes were made pre- and postoperatively and analyzed by video-topometery. RESULTS: With an average decrease of 4 D/mm the refractive change is inversely linear to the OZD. Changes of the CA showed significant variations between 22.5 degrees and 45 degrees, only. Mask guidance leads to the same amount of average refractive change. The deviation is +/- 3.4 D for the freehand application but only +/- 0.8 D for mask guidance. CONCLUSION: The data obtained in this in vitro study are transferred to a treatment nomogram describing the immediate postoperative refractive change, not identical with the final refraction. The results of the study are limited by the fact that astigmatism was induced in spherical corneas, rather than correcting preexisting ones.

Evolutionary age of the Galápagos iguanas predates the age of the present Galápagos islands.

New geological findings suggest that volcanoes existed over the Galápagos hotspot long before today's islands emerged less than 5 million years ago. The evolution of some of Galápagos' biota might have taken place on these former islands. This study investigates the evolutionary history of two of the archipelagos' older vertebrate taxa, the endemic Galápagos marine and land iguana (genera Amblyrhynchus and Conolophus). Mitochondrial rDNA sequences (in total about one kilobase of the 12S and 16S genes) were obtained from all extant genera of the family Iguanidae and the outgroup Oplurus. The phylogenetic analyses suggest that the Galápagos iguanas are sister taxa. Rate comparisons between the iguanid sequences and a corresponding set of sequences from ungulates with known fossil ages date their separation time at 10 million years, or more. The results strengthen the hypothesis that extended speciation times in the Galápagos are possible and provide an estimate of the minimum time inhabited islands of the archipelago may have existed.

Low genetic variability in a natural alpine marmot population (Marmota marmota, Sciuridae) revealed by DNA fingerprinting.

Genetic heterogeneity is usually considered an important factor for the viability of a population, yet there are cases in which populations sustain themselves despite virtual homozygosity. A prior step to studying the effects of such low levels of genetic variability can be the analysis of its causes. We analysed a population of the highly social alpine marmot (Marmota marmota, Sciuridae) by multilocus DNA fingerprinting. The fingerprint patterns revealed a very low degree of polymorphism in our main study population. We show that this lack of hypervariability is caused by a low effective population size, rather than by an unusual low mutation rate of the fingerprint loci studied. However, the current number of breeding pairs was found to be about an order of magnitude larger than the one that would be expected to lead to such a low degree of heterozygosity. We conclude that there must have been bottlenecks in the history of the Berchtesgaden marmot population that have severely affected its genetic heterozygosity.

Isolation of simple-sequence loci for use in polymerase chain reaction-based DNA fingerprinting.

Simple sequences are short regions of tandem repetitions of mono-, di-, tri-, or tetranucleotide motifs and occur as repetitive elements in all eukaryotic genomes. These regions tend to be hypervariable in length and can therefore be exploited for DNA fingerprinting purposes, using the polymerase chain reaction with primers flanking such regions. We describe how suitable simple-sequence loci can be isolated from any given eukaryotic DNA. We show the DNA sequences for a number of variants of such loci and discuss the current results on their usefulness for DNA fingerprinting.