Primary hyperparathyroidism (PHPT) is often associated with reduced bone mineral density (BMD). A randomized, double-blind, placebo-controlled trial was conducted to determine whether alendronate (ALN), 10 mg daily, maintains or improves BMD in patients with PHPT. Eligible patients had asymptomatic PHPT and did not meet surgical guidelines or refused surgery. Forty-four patients randomized to placebo or active treatment arms were stratified for gender. At 12 months, patients taking placebo crossed over to active treatment. All patients were on active treatment in yr 2. The primary outcome index, BMD, at the lumbar spine (LS), femoral neck, total hip, and distal one third radius was measured every 6 months by dual-energy x-ray absorptiometry. Calcium, phosphorous, PTH, bone-specific alkaline phosphatase (BSAP) activity, urinary calcium, and urinary N-telopeptide (NTX) excretion were monitored every 3 months. Treatment with alendronate over 2 yr was associated with a significant (6.85%; micro(d) = 0.052; +/-0.94% se; P < 0.001) increase in LS BMD in comparison with baseline. Total hip BMD increased significantly at 12 months with alendronate by 4.01% (micro(d) = 0.027; +/-0.77% se; P < 0.001) from baseline and remained stable over the next 12 months of therapy. BMD at the one third radius site did not show any statistically significant change in the alendronate-treated group at 12 or 24 months of therapy. At 24 months, the alendronate-treated group showed a 3.67% (micro(d) = 0.022; +/-1.63% se; P = 0.038) gain in bone density at the femoral neck site in comparison with baseline. The placebo group, when crossed over to alendronate at 12 months, showed a significant change of 4.1% (micro(d) = 0.034; +/-1.12% se; P = 0.003) in the LS BMD and 1.7% (micro(d) = 0.012; +/-0.81% se; P = 0.009) at the total hip site in comparison with baseline. There was no statistically significant change seen in the placebo group at 12 months at any BMD site and no significant change at 24 months for the distal one third radius or femoral neck sites. Alendronate was associated with marked reductions in bone turnover markers with rapid decreases in urinary NTX excretion by 66% (micro(d) = -60.27; +/-13.5% se; P < 0.001) at 3 months and decreases in BSAP by 49% at 6 months (micro(d) = -15.98; +/-6.32% se; P < 0.001) and by 53% at 9 and 12 months (micro(d) = -17.11; +/-7.85% se; P < 0.001; micro(d) = -17.36; +/-6.96% se; P < 0.001, respectively) of therapy. In the placebo group, NTX and BSAP levels remained elevated. Serum calcium (total and ionized), PTH, and urine calcium did not change with alendronate therapy. In PHPT, alendronate significantly increases BMD at the LS at 12 and 24 months from baseline values. Significant reductions in bone turnover occur with stable serum calcium and PTH levels. Alendronate may be a useful alternative to parathyroidectomy in asymptomatic PHPT among those with low BMD.
While mean intraocular pressure (IOP) has long been known to correlate with glaucomatous damage, the role of IOP fluctuation is less clearly defined. There is extensive evidence in the literature for and against the value of short-term and long-term IOP fluctuation in the evaluation and prognosis of patients with glaucoma. We present here the arguments made by both sides, as well as a discussion of the pitfalls of prior research and potential directions for future studies. Until a reliable method is developed that allows for constant IOP monitoring, many variables will continue to hinder us from drawing adequate conclusions regarding the significance of IOP variation.
Purpose
To determine the in vivo elastic modulus of the human cornea using vibrational optical coherence tomography (VOCT).
Methods
Vibrational analysis coupled with optical coherence tomography (OCT) was used to obtain the resonant frequency (RF) and elastic modulus of corneal structural components. VOCT corneal thickness values were measured using OCT images and correlated with corneal thickness determined with Pentacam (Oculus, Wetzlar, Germany). Moduli were obtained at two locations: central cornea (CC) and inferior cornea (IC). Measurements were obtained with and without anesthetic eye drops to assess their effect on the modulus measurements.
Results
VOCT thickness values correlated positively (
R
2
= 0.97) and linearly (y = 1.039x–16.89) with those of Pentacam. Five RF peaks (1–5) were present, although their presence was variable across eyes. The RF for peaks 1 to 5 in the CC and IC ranged from 73.5 ± 4.9 to 239 ± 3 Hz and 72.1 ± 6.3 to 238 ± 4 Hz, respectively. CC and IC moduli for peaks 1 to 5 ranged from 1.023 ± 0.104 to 6.87 ± 0.33 MPa and 0.98 ± 0.15 to 6.52 ± 0.79 MPa, respectively. Topical anesthesia did not significantly alter the modulus (
P
> 0.05 for all), except for peak 2 in the CC (
P
< 0.05).
Conclusions
This pilot study demonstrates the utility of VOCT as an in vivo, noninvasive technology to measure the elastic modulus in human corneas. The structural origin of these moduli is hypothesized based on previous reports, and further analyses are necessary for confirmation.
Translational Relevance
This work presents VOCT as a novel approach to assess the in vivo elastic modulus of the cornea, an indicator of corneal structural integrity and health.
At the 6-month follow-up, non-topography-guided PRK after ICRS implantation and CXL was found to be an effective and safe option for correcting residual refractive error and improving visual acuity in patients with moderate keratoconus.
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