Abstract Objective To analyze the changing trends in corneal transplantation techniques and the way selective lamellar transplantation has influenced our practice. Design Retrospective survey of all ...corneal transplants performed by a single practice at Toronto Western Hospital. Participants All corneal transplants performed by our office since 2002, the year we performed our first lamellar transplant. Methods We retrospectively reviewed all keratoplasty procedures performed in our office between January 2002 and December 2010. Procedures were classified as penetrating keratoplasty (PKP); deep lamellar endothelial keratoplasty (DLEK); Descemet's stripping automated endothelial keratoplasty (DSAEK); or deep anterior lamellar keratoplasty (DALK). Results A total of 1104 procedures were performed in this period (average, 122.6 per year). Of these, 654 were PKPs (59.3%); 107 DLEKs (9.7%); 219 DSAEKs (19.8%); and 124 DALKs (11.2%). The number of PKPs performed decreased by 61.8% over this 9-year survey. For the last 4 years of the study, the proportions of PKP, DSAEK, and DALK procedures performed were 41%, 40%, and 19%, respectively. Conclusions This 9-year audit showed that in less than a decade since its introduction at our institution, selective lamellar transplantation has become the procedure of choice for corneal keratoplasty, accounting for 59% of all transplants performed over the past 4 years.
To evaluate the predisposing factors, indications and coincident procedures in patients requiring a secondary intraocular lens (IOL)-related intervention. We reviewed data on 183 consecutive ...secondary IOL-related procedures. Information collected included demographics, predisposing factors, IOL status, indication for surgery, coincident procedures, and final IOL location and fixation method. Of the 183 procedures performed, 73 were secondary IOL implantations, 68 were IOL exchanges and 42 were IOL repositionings. Predisposing factors were found in 88.6 % of the cases, the most common being complicated cataract surgery (39.8 %) followed by trauma (20.2 %). The most common indications for surgery in the anterior chamber IOL and posterior chamber IOL groups were pseudophakic bullous keratopathy ± failed graft (77.2 %) and subluxated IOL (57.53 %), respectively. A malpositioned or subluxated lens was found in 47.86 % of all pseudophakic eyes. A simultaneous procedure was performed in 67 % of cases, anterior vitrectomy being the most common (43.7 %), followed by keratoplasty (35 %). Secondary IOL-related interventions were associated with predisposing factors, complicated cataract surgery being the most common. Patients implanted with anterior chamber IOLs seemed to have a more complicated course requiring more complex secondary surgeries and associated procedures.
To evaluate the pituitary–adrenal axis function by means of the adrenocorticotropic hormone (ACTH) stimulation test following a single intravitreal injection of triamcinolone acetonide (IVTA). ...Prospective comparative clinical interventional study. Twenty-eight patients (28 eyes) received a single IVTA (4 mg in 0.1 ml) for macular edema. The basal cortisol level and the response to 1 μg adrenocorticotropic hormone stimulation were determined on the morning before IVTA injection and at 1 day and 1, 2, and 4 weeks after IVTA injection. Results were compared with those obtained from a control group of 50 healthy subjects. All patients in the study had normal basal cortisol and normal response to ACTH challenge before receiving IVTA. 1 day following IVTA, basal cortisol was suppressed in one patient in the study group. Fasting serum cortisol levels at 1, 2, and 4 weeks after IVTA injection were normal in all patients in the study group. 1 day following IVTA, the peak response to ACTH at 30 min was blunted in four patients (14.3 % of the study group,
p
= 0.05) and the cortisol response at 60 min was suppressed (
p
= 0.009). 1 week following IVTA, the response to ACTH challenge was blunted in only one patient. A single IVTA injection may be associated with impaired hypothalamic–pituitary–adrenal function in some patients during the first 24 h following IVTA.
Reverberation mapping of nearby active galactic nuclei (AGNs) has led to estimates of broad-line region (BLR) sizes and central object masses for some 37 objects to date. However, successful ...reverberation mapping has yet to be performed for quasars of either high luminosity (above unk< similar to 10 super(46)ergs s super(-1))or high redshift (z unk 0.3). Over the past 6 years, we have carried out, at the Hobby-Eberly Telescope, rest-frame ultraviolet spectrophotometric monitoring of a sample of six quasars at redshifts: z = 2.2-3.2, with luminosities of unk similar to 10 super(46.4) 10 super(47.6) ergs s super(-1) an order of magnitude greater than those of previously mapped quasars. The six quasars, together with an additional five having similar redshift and luminosity properties, were monitored photometrically at the Wise Observatory during the past decade. All 11 quasars monitored show significant continuum variations of order 10%-70%. This is about a factor of 2 smaller variability than for lower luminosity quasars monitored over the same rest-frame period. In the six objects that have been spectrophotometrically monitored, significant variability is detected in the C Iv lambda 1550 broad emission line. In several cases the variations track the continuum variations in the same quasar, with amplitudes comparable to, or even greater than, those of the corresponding continua. In contrast, no significant Lya variability is detected in any of the four objects in which it was observed. Thus, UV lines may have different variability trends in high-luminosity and low-luminosity AGNs. For one quasar, S5 0836+71 at z = 2.172, we measure a tentative delay of 595 days between C Iv and UV continuum variations, corresponding to a rest-frame delay of 188 days and a central black hole mass of 2.6 x 10 super(9) M unk.
We reinvestigate the relationship between the characteristic broad-line region size (R sub(BLR)) and the Balmer emission-line, X-ray, UV, and optical continuum luminosities. Our study makes use of ...the best available determinations of R sub(BLR) for a large number of active galactic nuclei (AGNs) from Peterson et al. Using their determinations of R sub(BLR) for a large sample of AGNs and two different regression methods, we investigate the robustness of our correlation results as a function of data subsample and regression technique. Although small systematic differences were found depending on the method of analysis, our results are generally consistent. Assuming a power-law relation R sub(BLR) 8 L super(a), we find that the mean best-fitting a is about 0.67 c 0.05 for the optical continuum and the broad Hb luminosity, about 0.56 c 0.05 for the UV continuum luminosity, and about 0.70 c 0.14 for the X-ray luminosity. We also find an intrinsic scatter of 640% in these relations. The disagreement of our results with the theoretical expected slope of 0.5 indicates that the simple assumption of all AGNs having on average the same ionization parameter, BLR density, column density, and ionizing spectral energy distribution is not valid and there is likely some evolution of a few of these characteristics along the luminosity scale.
To report the outcomes of repeat endothelial keratoplasty (EK) in patients with previous failed deep lamellar endothelial keratoplasty (DLEK).
This retrospective interventional case series involved ...the review of clinical records of patients with failed DLEK surgery who underwent repeat EK surgery.
Ten eyes of 9 patients (2 men and 7 women) were included. The mean age at initial DLEK surgery was 71.2 ± 8.0 years (range, 59-80 years), and the duration to repeat EK was 47 ± 14.3 months (range, 16-63 months). Removal of the failed DLEK donor disc was performed in 7 eyes (70%); in 3 eyes (30%), repeat EK was performed without removal of the failed donor disc. The mean follow-up after repeat EK surgery was 21.7 months (range, 3-44 months). Improvements in corneal clarity and visual acuity were obtained in all eyes. Mean preoperative logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) was 1.46 (20/577; range, 20/100 to counting fingers) and improved to 0.64 (20/87; range, 20/30 to 20/300) at the final follow-up (P = 0.03). Four eyes had limited BCVA secondary to ocular comorbidites, including age-related macular degeneration, cystoid macular edema, and advanced glaucomatous optic neuropathy. No significant postoperative complications were noted after repeat EK surgeries.
Repeat EK in patients with late DLEK failure is effective in improving corneal clarity and is a viable alternative to penetrating keratoplasty (PK). Surgery may be performed with or without removal of the failed donor disc. Visual outcomes may be limited by the existence of ocular comorbidities.
Microlensing is the only known direct method to measure the masses of stars that lack visible companions. In terms of microlensing observables, the mass is given by M = (c super(2)/4G) r sub(E)f ...sub(E) and so requires the measurement of both the angular Einstein radius f sub(E) and the projected Einstein radius r sub(E). Simultaneous measurement of these two parameters is extremely rare. Here we analyze OGLE-2003-BLG-238, a spectacularly bright (I sub(min) = 10.3), high-magnification (A sub(max) = 170) microlensing event. Pronounced finite-source effects permit a measurement of f sub(E) = 650 kas. Although the timescale of the event is only t sub(E) = 38 days, one can still obtain weak constraints on the microlens parallax: 4.4 AU < r sub(E) < 18 AU at the 1 s level. Together these two parameter measurements yield a range for the lens mass of 0.36 M sub( )< M < 1.48 M sub( ). As was the case for MACHO-LMC-5, the only other single star (apart from the Sun) whose mass has been determined from its gravitational effects, this estimate is rather crude. It does, however, demonstrate the viability of the technique. We also discuss future prospects for single-lens mass measurements.
Growing observational evidence indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z ~ 5-7 galaxies. In this paper, we present the most direct ...observational evidence thus far for ubiquitous high-equivalent-width (EW) OIII + H beta line emission in Lyman-break galaxies at z ~ 7, and we present a strategy for an improved measurement of the sSFR at z ~ 7. We accomplish this through the selection of bright galaxies in the narrow redshift window z ~ 6.6-7.0 where the Spitzer/Infrared Array Camera (IRAC) 4.5 mu m flux provides a clean measurement of the stellar continuum light, in contrast with the 3.6 mu m flux, which is contaminated by the prominent OIII + H beta lines. We can also set a robust lower limit of gap4 Gyr super(-1) on the sSFR of our sample based on the mean spectral energy distribution.
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