Holocene coastal evolution of Colorado River Delta based on diatom assemblages, Northern Patagonia, Argentina.

Diatom assemblages and coastal sedimentary facies succession in the deltaic plain of the Colorado River (Argentina) were studied in order to reconstruct the environment conditions in response to Holocene eustatic sea-level changes and delta progradation. Samples were selected from a 200-cm core (39°35'52" S, 62°6'43" W). Chronology was based on radiocarbon datings in bulk samples and mollusk shells. Nine lithological units were recognized where fine and very fine sand predominate. The core sediments were dominated by tychoplanktonic coastal-marine diatoms. The accompanying flora included stable marine-coastal taxa and allochthonous fluvial fresh-brackish species. Three diatom zones (DZ) were established based on cluster analyses. The LCH site was significantly affected by Late Pleistocene and Holocene sea-level fluctuations, and the progradation of the deltaic lobe during the last ca. 7,000 14C yr. BP. Ancient tidal channels were flooded in the early Holocene postglacial transgression. Erosive and re-working processes associated with the formation of estuarine channels, affected valves preservation, yielding with barren sections. Tidal flats and marshes have developed in the area during the late Holocene regression phase. The comparison of the sedimentary sequence with deltaic facies evolution models, confirm the presence of a hiatus, which masks the Holocene Maximum and highstand.

Periocular port wine stain: the great ormond street hospital experience.

PURPOSE: To identify the sensitivity and specificity of risk factors for the development of glaucoma in patients with port wine stain (PWS). DESIGN: A retrospective case-control study involving a large cohort of patients with PWS. PARTICIPANTS: A total of 216 patients (total of 252 eyes) with unilateral or bilateral PWS seen in the eye department in Great Ormond Street Hospital, London, United Kingdom. METHODS: We studied the anatomic distribution of PWS and the incidence of choroidal hemangioma, episcleral hemangioma, iris heterochromia, and Sturge-Weber syndrome (SWS). We analyzed the sensitivity and specificity of these features as risk factors for glaucoma. MAIN OUTCOME MEASURES: Development of glaucoma. RESULTS: Mean age at presentation was 2.9 years (3 weeks to 18.8 years). Mean follow-up was 3.2 years (0-15 years). A total of 180 patients (83.3%) had unilateral lesion, and 36 patients (16.7%) had bilateral lesion. Thirty-one patients (14.3%) had isolated V1 lesion, 35 patients had V2 lesion only (16.2%), and 93 patients (43%) had both V1 and V2 involved. On the last visit, 46 eyes (18.3%) in 39 patients had glaucoma; their mean age was 3.25 years. Glaucoma was more common if PWS was bilateral (P=0.0001), both upper and lower lids were involved (P < 0.0001), and episcleral hemangioma (P < 0.0001), iris heterochromia (P=0.004), or choroidal hemangioma (P < 0.0001) was present. Twenty-four patients had SWS; this was significantly associated with upper lid PWS (P=0.001) and bilateral PWS (P=0.0003). Glaucoma was more common in patients with SWS compared with those without (66.7% vs. 18%, P=0.01). Combined upper and lower lid PWS, episcleral hemangioma, SWS, and iris heterochromia are sensitive prognosticators for the development of glaucoma. CONCLUSIONS: Iris heterochromia is associated with the development of early glaucoma in patients with PWS. Patients at high risk of glaucoma should be seen more often in clinic. Patients who do not have combined lid involvement or episcleral hemangioma have a lower risk and can therefore be seen less often in clinic. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Amniotic membrane transplantation in children with symblepharon and massive pannus.

OBJECTIVE: To report our pediatric experience with amniotic membrane transplantation for ocular surface and forniceal reconstruction. METHODS: Retrospective case review of children who underwent superficial keratectomy, symblepharon lysis, and forniceal reconstruction using amniotic membrane transplantation. The underlying diagnosis, visual acuity, level of discomfort at first and last visits, and surgical details were noted. RESULTS: Four patients (5 eyes) were included. Two patients had epidermolysis bullosa (1 recessive dystrophic and 1 junctional), 1 had laryngo-onychocutaneous syndrome, and 1 had measles-related keratitis and was positive for human immunodeficiency virus. Their mean age when initially seen was 8.7 years (age range, 4-16 years), and mean follow-up was 18.25 months (range, 12-29 months). The mean visual acuity preoperatively was 1.1 logMAR (logarithm of the minimum angle of resolution) (range, 1-1.3), and postoperatively was 0.7 (range, 0.2-1.2). All patients experienced increased ocular comfort with anatomical restoration of corneal and conjunctival surfaces. Visual acuity improved in 3 eyes. Only the patient with laryngo-onychocutaneous syndrome had recurrence of granuloma, at 9 months after surgery. CONCLUSION: Amniotic membrane transplantation with symblepharon lysis is effective for ocular surface reconstruction in the management of epidermolysis bullosa and other conditions that cause corneal scarring and symblepharon in children. In this small series, children with epidermolysis bullosa fared better and the effects of surgery lasted longer compared with patients with other causes of symblepharon and massive pannus.

Presence of mitomycin-C in the anterior chamber after photorefractive keratectomy.

PURPOSE: To assess the presence of mitomycin-C (MMC) in hen aqueous humor after photorefractive keratectomy (PRK). SETTING: Instituto Universitario de Oftalmobiología Aplicada, Faculty of Medicine, University of Valladolid, and Department of Analytical Chemistry, Faculty of Sciences, University of Valladolid, Valladolid, Spain. METHODS: Mitomycin-C 0.02% was applied topically for 2 minutes to a right hen's eye after PRK (Group A) and to the left eye with intact epithelium (Group B). At different time points (10, 30, 60, 360, and 720 minutes), aqueous humor was extracted and high-performance liquid chromatography was performed to detect and quantify MMC levels. RESULTS: The mean maximum drug concentration of MMC measured in the aqueous humor was 187.250 microg/L +/- 4.349 (SD) in Group A and 93.000 +/- 4.899 microg/L in Group B, both detected 10 minutes after topical application. Statistically significant differences were found between Groups A and B at 10, 30, and 60 minutes, with decreasing MMC levels in both groups but a higher concentration in Group A. After 360 minutes, MMC levels were undetectable in Group B and after 720 minutes in Group A. CONCLUSIONS: Mitomycin-C was detectable in the aqueous humor of the hen eye after topical application in PRK-treated eyes and in eyes with intact epithelium. The presence of MMC is of concern as it may lead to ocular toxicity in the long term.

Reproducibility of LASIK flap thickness using the Hansatome microkeratome.

PURPOSE: To evaluate the actual versus the expected thickness of laser in situ keratomileusis (LASIK) flaps and to determine the factors that affect flap thickness. SETTING: Centre For Sight, Queen Victoria Hospital, East Grinstead, United Kingdom. METHODS: A retrospective analysis of LASIK procedures in 757 consecutive eyes was done. The surgery was performed by a single surgeon using 2 Hansatome microkeratomes (Bausch & Lomb) with 160 microm and 180 microm heads. Patient age, preoperative manifest refraction, automated keratometry, preoperative central pachymetry, and intraoperative stromal pachymetry were evaluated to determine whether they influenced the actual flap thickness. RESULTS: Bilateral LASIK was performed in 343 patients (686 eyes). The 160 microm head was used in 641 eyes (84.6%) (Group 1) and the 180 microm head, in 116 eyes (15.4%) (Group 2). The mean preoperative manifest refraction spherical equivalent (SE) was -3.9 diopters (D) +/- 4.5 (SD) (range +7.4 to -25.0 D) in Group 1 and -4.4 +/- 3.7 D (range +7.1 to -12.9 D) in Group 2. The mean preoperative keratometry reading was 43.6 +/- 1.8 D (range 36.0 to 48.6 D) and 43.6 +/- 1.8 D (range 35.9 to 47.0 D), respectively; the mean preoperative central pachymetry was 543 +/- 35 microm (range 447 to 643 microm) and 548 +/- 31 microm (range 453 to 613 microm), respectively; and the mean flap thickness was 116.4 +/- 19.8 microm and 117.3 +/- 18.0 microm, respectively. The difference between the actual and the expected flap thickness in each group was statistically significant (P<.001). There was no significant difference in the actual flap thickness between the 2 Hansatomes. The preoperative SE and central pachymetry were the only factors that influenced the actual flap thickness (P<.05); thin flaps were more common with increasing myopia and increasing corneal thickness. CONCLUSIONS: Spherical equivalent and preoperative pachymetry were the principal factors that influenced flap thickness. Preoperative keratometry values and patient age did not influence the actual flap thickness.