The cortisol awakening response predicts major depression: predictive stability over a 4-year follow-up and effect of depression history.

BACKGROUND: The cortisol awakening response (CAR) has been shown to predict major depressive episodes (MDEs) over a 1-year period. It is unknown whether this effect: (a) is stable over longer periods of time; (b) is independent of prospective stressful life events; and (c) differentially predicts first onsets or recurrences of MDEs. METHOD: A total of 270 older adolescents (mean age 17.06 years at cortisol measurement) from the larger prospective Northwestern-UCLA Youth Emotion Project completed baseline diagnostic and life stress interviews, questionnaires, and a 3-day cortisol sampling protocol measuring the CAR and diurnal rhythm, as well as up to four annual follow-up interviews of diagnoses and life stress. RESULTS: Non-proportional person-month survival analyses revealed that higher levels of the baseline CAR significantly predict MDEs for 2.5 years following cortisol measurement. However, the strength of prediction of depressive episodes significantly decays over time, with the CAR no longer significantly predicting MDEs after 2.5 years. Elevations in the CAR did not significantly increase vulnerability to prospective major stressful life events. They did, however, predict MDE recurrences more strongly than first onsets. CONCLUSIONS: These results suggest that a high CAR represents a time-limited risk factor for onsets of MDEs, which increases risk for depression independently of future major stressful life events. Possible explanations for the stronger effect of the CAR for predicting MDE recurrences than first onsets are discussed.

[Scattered light and glare sensitivity after wavefront-guided photorefractive keratectomy (WFG-PRK) and laser in situ keratomileusis (WFG-LASIK)]. / Lumière diffractée et sensibilité à l'éblouissement après PKR et LASIK guidés par front d'onde.

PURPOSE: To compare glare sensitivity measured by the intraocular scattered light between WFG-PRK and WFG-LASIK at 12 months follow-up and to assess its correlation to patients' complaints. PATIENTS AND METHODS: Prospective and randomized study on 13 patients treated with WFG-LASIK, 13 patients with WFG-PRK and a control group of 35 patients. The intraocular stray light was measured by the Oculus C-Quant 12 months after surgery and before surgery for the control group. Photopic and mesopic contrast acuity and glare symptoms were reported pre- and postoperatively. RESULTS: Stray light values were normal in 79% of patients after WFG-LASIK and PRK and 86% in the control group, with mean values of 1.05 log, 1.03 log, and 0.99 log, respectively (p>0.05). All the patients with significant glare complaints had impaired stray light values versus 31.5% in the no-complaint group. Photopic and mesopic contrast acuity and glare symptoms were improved 1 year after surgery compared to preoperatively (no significant difference between groups). CONCLUSION: WFG-LASIK and PRK are safe and equivalent procedures regarding quality of vision. The measurement of stray light can be a discriminative test to assessing patients' glare complaints.

Real time intraocular pressure and lamellar corneal flap thickness in keratomileusis.

BACKGROUND: To measure real time intraocular pressure (IOP) during keratomileusis and to determine variability of corneal flap thickness by using different suction ring pressure settings. METHODS: Eight human cadaver eyes, two groups of four each, were used. The suction ring of the UniversalKeratome was applied to each eye, the same as for a standard automated lamellar keratoplasty (ALK) or laser in situ keratomileusis (LASIK) procedure, to create a lamellar corneal flap. The pressure of the suction ring on each eye was raised to one of two different levels, four eyes to 488 and the remaining four to 600 mm Hg. IOP was continuously recorded by manometer, from application of the suction ring through the end of the passage of the microkeratome. Central corneal thickness was measured, both before and after each procedure. RESULTS: IOP increased by >90 mm Hg after application of the suction ring at a pressure of either 488 mm Hg or 600 mm Hg. Corneal flaps performed under a suction ring pressure of 488 mm Hg measured 159.98+/-5 microm, whereas flap thickness for the 600-mm Hg group varied 1.4-266.2 microm. Two flaps exhibited irregular configurations. CONCLUSIONS: Real time IOP can be measured during keratomileusis. The results demonstrated a significant increase in IOP during the procedure. Suction ring pressure setting is an important variable in determining consistent corneal flap thickness during the keratomileusis procedure.

Ejection from an aircraft following photorefractive keratectomy: a case report.

A 32-yr-old active duty United States Navy Lieutenant Naval Flight Officer (NFO), 6 mo status post photorefractive keratectomy (PRK) in both eyes performed as part of the first protocol to evaluate laser refractive surgery in aviators, ejected from a Navy S-3B Viking aircraft while performing field carrier landing practice. Neither the pilot nor the NFO suffered physical consequences as a result of the ejection. Coincidentally, the NFO had been examined just 1 wk before the mishap and was noted to have uncorrected visual acuity of 20/16 in each eye. Examination 1 wk following the mishap could not detect a change in vision. The NFO's vision status and his post-PRK status was not listed as a causal factor in the mishap. While this case report will not settle the debate regarding the appropriateness of refractive surgery in aviators, it does provide anecdotal evidence to support the safety of PRK in the aviation community.

Bandage soft contact lens barrier function: a clinical research note.

Corneal thickness pre- and post-operatively was measured on 18 volunteer subjects within the context of a clinical investigation of laser refractive surgery. All measurements were taken with regard for time of day, in order to counter any complicating diurnal influence on data accuracy. Of the 18 subjects, six lost or had accidently displaced their overnight bandage soft contact lenses the first night immediately after surgery, and 12 retained theirs. The individuals with lost bandage lenses exhibited uniformly thick, swollen corneas. In contrast, the other 12 subjects, with retained lenses, exhibited a stable corneal thickness map, displaying the characteristic relatively thick periphery that transitions to a thinner central region. Moreover, in the six affected subjects, application of a new overnight bandage lens resulted in recovery of the normal thickness pattern on day 2, as opposed to the uniform swelling or oedema of the previous day. In combination, these findings indicate a fluid barrier function on behalf of the bandage soft contact lenses, which allowed the corneal endothelial pump mechanism to counteract any extreme swelling or fluid accumulation. This previously unreported phenomenon helps explain the historical effectiveness of this treatment regimen for corneal bullous, or excessive fluid-retention, conditions.

Orbscan pachymetry: implications of a repeated measures and diurnal variation analysis.

INTRODUCTION: Corneal thickness changes reflect alterations in hydration and metabolism. Ultrasound pachymetry determinations may be adversely influenced by fluctuations in tissue hydration, whereas optical systems are apparently unaffected by these fluxes. A recently marketed, optical-based, topographic mapping system (Orbscan; Orbtek, Inc.) uses anterior and posterior corneal surface data to calculate corneal thickness. OBJECTIVE: This new instrumentation presents as a potentially useful pachymetry tool for evaluation of corneas under hydration flux or challenge (e.g., postphotorefractive keratectomy [PRK] healing studies) and was therefore evaluated for accuracy and variability. MEASUREMENTS: Three calibrated standards were measured in repeated fashion. Additionally, 1 test subject was measured 30 times in 1 day (5 measurements each at 8:00, 9:30, and 11:00 AM and at 1:00, 2:30, and 4:00 PM). Corresponding measurements were made at 8:00 and 11:00 AM and at 4:00 PM on 3 separate days to assess repeatability. Grouped data from 18 volunteer subjects were compared to the data of the test subject as well. RESULTS: Pachymetry accuracy on a calibrated standard was determined to be +/-2 microm (standard deviation, n = 12). Repeated measures on the subject demonstrated a mean standard deviation of 9.08 microm for 750 thickness data points across the central 7 mm of the cornea; peripheral measurement points exhibited progressively greater variability than at the apex (analysis of variance; P<0.0001). A plot of thickness by corneal location and time of day exhibited a diurnal pattern, with the peripheral cornea exhibiting progressively greater thickness changes than the central cornea (two-way analysis of variance; P<0.00001). The data significantly correlated across days when all times of day were considered (r = 0.999). However, thickness values obtained at 8:00 AM were significantly different across days (t test; P<0.0002). The subject's data correlated very well (r = 0.9996) with the grouped volunteer data. CONCLUSIONS: These data show this system to be useful in corneal research and in clinical settings. The data confirm early morning pachymetry to be highly variable. Additionally, the data not only indicate a diurnal variation of corneal hydration over time, but also imply the presence of a diurnal-based hydration gradient across the peripheral cornea, both of which can have significance for PRK, since excimer tissue ablation effectiveness is influenced by tissue hydration.

The effect of excimer laser photorefractive keratectomy for myopia on nerve fiber layer thickness measurements as determined by scanning laser polarimetry.

OBJECTIVE: Scanning laser polarimetry measures the retardation of polarized laser light as it passes through the birefringent retinal nerve fiber layer (RNFL). Because retardation is directly proportional to the number of retinal nerve fibers, indirect measurements of the RNFL thickness are obtained. A fixed compensatory mechanism is used to correct for retardation attributed to birefringence in the cornea and anterior segment. Excimer laser photorefractive keratectomy (PRK) corrects myopia by ablating tissue from the cornea. This study was conducted to determine the effect of this ablation on RNFL measurements. DESIGN: Prospective comparative case series. PARTICIPANTS: Eighteen patients. METHODS: Patients undergoing PRK had RNFL measurements performed with the GDx Nerve Fiber Analyzer (Laser Diagnostic Technologies, San Diego, CA), a scanning laser polarimeter, in both eyes before and 90 days after PRK in the first eye. MAIN OUTCOME MEASURES: Fourteen different GDx parameters were analyzed for statistically significant differences preoperatively and 3 months postoperatively in the treated and untreated eye using Hotelling's T-squared generalized means test. RESULTS: Eighteen patients underwent PRK in the nondominant eye first. Preoperative refractions averaged -3.8+/-1.6 diopters (D), with an average correction of 3.4+/-1.9 D, corresponding to 49.7+/-20.5 microns of ablation. There were no statistically significant preoperative differences between the fellow eyes in refractive error (P = 0.65). Postoperatively, there were no statistically significant changes in any GDx parameter in the treated eye compared with the untreated control eye (P = 0.21). CONCLUSIONS: Excimer laser PRK for moderate myopia has no significant effect on RNFL thickness measurements as determined by scanning laser polarimetry.

Significance of corneal topography in predicting patient complaints after photorefractive keratectomy.

PURPOSE: To evaluate the sensitivity and specificity of postoperative corneal topography to predict potential patient complaints after photorefractive keratectomy (PRK). SETTING: Doheny Eye Institute, Los Angeles, California, USA. METHODS: Postoperative tangential corneal topographic maps, in 0.5 and 1.0 diopter (D) relative scales, were obtained from patients (n = 34) at least 4 months after PRK. Topographies of complaining (n = 18) and noncomplaining patients (n = 16) were analyzed by 6 masked examiners with 2 different experience levels in PRK (experts, n = 2; beginners, n = 4), who assigned the topographies to 1 of the 2 groups. RESULTS: Topographies of complainers (sensitivity) and noncomplainers (specificity) were correctly classified in 53.2% overall and in 44.0% and 63.5% (P = .06) in complainers and noncomplainers, respectively. Experienced examiners were not significantly more accurate than inexperienced examiners (46.3% and 56.6%, respectively; P = .09). Images of 1.0 D scales received significantly more correct responses than those of 0.5 D scales (56.4% and 50.0% respectively; P = .03). The reproducibility between images for the same patient in both scales was significantly better for the experienced examiners than the inexperienced examiners (kappa coefficient 0.73 and 0.51, respectively; P = .05). CONCLUSIONS: Subjective analysis of postoperative corneal topography alone is not sufficient to predict potential patient complaints after PRK. Topographic findings should be interpreted only in the context of a complete clinical examination.

Photorefractive keratectomy in African Americans including those with known dermatologic keloid formation.

PURPOSE: To report the outcome of photorefractive keratectomy in African Americans, including those with a known history of dermatologic keloid formation. METHODS: A retrospective analysis of African American patients who had photorefractive keratectomy at either of our institutions was undertaken to identify all patients who were at least 3 months status-post refractive surgery. The presence or absence of a history of keloid formation, as well as preoperative and postoperative measurements of uncorrected visual acuity, best-corrected visual acuity, manifest refraction, and the presence and magnitude of any postoperative corneal haze were analyzed. RESULTS: Twelve patients (19 eyes) met the inclusion criteria and three of these patients (six eyes) had a history of keloid formation. Mean uncorrected visual acuity +/- SD for the entire study group improved from 20/369 +/- 20/270 preoperatively to 20/19.4 +/- 20/7.1 postoperatively (average follow-up, 13.8 months). All eyes had postoperative uncorrected visual acuity of 20/40 or better; 14 (74%) achieved 20/20 or better. Mean best spectacle corrected visual acuity went from 20/14.8 +/- 20/2.8 preoperatively to 20/15.5 +/- 20/3.2 postoperatively (not statistically significant). Mean manifest spherical equivalent was -4.9 +/- 3.4 diopters preoperatively and +0.03 +/- 0.55 diopters postoperatively. Eight eyes (42%) had trace to 1+ corneal haze following photorefractive surgery. A comparison of postoperative uncorrected and best-corrected visual acuities of known keloid formers with nonkeloid formers revealed no significant statistical difference. CONCLUSIONS: African Americans may have excellent visual outcomes following photorefractive keratectomy. History of keloid formation does not appear to have an adverse effect on the outcome. These results question whether known dermatologic keloid formation should be a contraindication to photorefractive keratectomy.

Radial keratotomy learning curve using the American technique.

PURPOSE: To delineate the learning curve for a beginning refractive surgeon using the centrifugal (American) technique. SETTING: Naval Medical Center, San Diego, California, USA. METHODS: The first 100 radial keratotomy (RK) cases (51 patients) of one surgeon, divided into five sequential groups of 20, were retrospectively reviewed. All patients had RK using the American technique. Emmetropia was the goal in all patients. Groups were compared with respect to preoperative refractive status, age, sex, and outcome. Outcomes analysis included visual acuity, refractive error, complications, and enhancement rates. Data were reviewed preoperatively and 1 and 3 months postoperatively. RESULTS: All five groups were age and sex matched. There was no difference in preoperative refractive error among the five groups. Sequential improvement in early postoperative refractive error from a mean of -1.73 diopters (D) +/- 1.00 (SD) (first 20) to 0.45 +/- 0.55 D (last 20) (P < .001) and decreased enhancement rates from 50% (first 20) to 0% (last 20) (P = .002) were statistically significant. Visual acuity at 1 month was 20/40 or better in 47% of patients in Group 1 (first 20), whereas all patients in Group 5 (last 20) had an acuity better than 20/40 (P < .001). There was no significant difference in complication rates among the five groups. CONCLUSION: The results of RK using the American technique can improve significantly with surgeon experience. Enhancement rates decreased with experience, and there was no difference in complication rates during the learning period of one surgeon.

Topographic detection of photorefractive keratectomy.

PURPOSE: This study aimed to evaluate the sensitivity and specificity of subjective review of corneal topography to detect patients who have undergone photorefractive keratectomy (PRK). METHODS: Topographic maps from 3 different devices were obtained from 19 patients with postoperative PRK and 9 control subjects with emmetropia and 10 control subjects with myopia. Each image was printed in an absolute and relative scale (total of 228 maps) and graded for overall shape and pattern. Fifteen masked reviewers independently rated each map as either postoperative PRK or not. RESULTS: The overall sensitivity (ability to detect PRK) and specificity rates (ability to exclude control subjects) by reviewers were 65% and 93%, respectively. Sensitivity was influenced independently by the scale (relative, 68%; absolute, 62%; P < 0.01), experience of reviewer (experienced, 77%; inexperienced, 53%; P < 0.001), and device (Alcon, 67 +/- 29.9; Eyesys, 75 +/- 29.4%; and Tomey, 54 +/- 31.7%; P < 0.001). Low levels of preoperative myopia were consistently more difficult to detect than higher levels (low myopia -1.50 to -2.99 diopters [D] sensitivity: 53 +/- 34.5%; medium level -3.00 to -4.49 D: 67 +/- 28.9%; and high level -4.50 to -6.00 D: 77 +/- 21.1%; P < 0.0001). Differences in specificity between experienced and inexperienced reviewers were obtained when maps had a homogeneous topographic pattern (97 +/- 5.6% and 85 +/- 13.7%, respectively; P < 0.05). Several control topography patterns (e.g., homogeneous, focal, and keyhole) were disproportionately more difficult to correctly identify on the Eyesys device. CONCLUSIONS: Topographic experience is a significant factor influencing the correct identification of PRK. Techniques also can be used to enhance detection, such as the use of different devices and scales. However, if subjective review of topography is used as the only method of detection, many patients with PRK will not be identified properly. In addition, the most prevalent preoperative myopic category in the general population (myopia < -3.00 D) also is the most difficult to detect after treatment. This reduces the usefulness of topography as a screening tool. Other techniques are needed to improve the detection of patients with postoperative PRK.

Refractive changes during 72-hour exposure to high altitude after refractive surgery.

PURPOSE: The authors prospectively analyzed refractive and pachymetric parameters during exposure to high altitude after radial keratotomy (RK) and photorefractive keratectomy (PRK). METHODS: The authors measured manifest and cycloplegic refraction, keratometry, computed video keratography, and central and peripheral pachymetry in six subjects who have undergone RK (11 eyes), six who have undergone PRK (12 eyes), and nine with myopia (17 eyes) at sea level and on three consecutive days at 14,100 feet. All measurements were repeated 1 week after subjects returned to sea level. RESULTS: Subjects who have undergone RK demonstrated a significant and progressive increase in spherical equivalence (+0.30 +/- 0.50 diopters on day 1 and +1.52 +/- 1.01 diopters on day 3; P < 0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P < 0.004; PRK, P < 0.007; control subjects, P = 0.0006) by day 3 at high altitude. Refraction, keratometry, and pachymetry returned to baseline (P = 1.000) after return to sea level. CONCLUSIONS: Seventy-two-hour exposure to high altitude in subjects who have had RK induces a significant, progressive, and reversible hyperopic shift in refraction with corresponding video keratographic and keratometric changes. The authors hypothesize that the high-altitude hypoxic environment causes increased corneal hydration in the area of the RK incisions, which may lead to central corneal flattening and a hyperopic shift in refractive error. Subjects who have had PRK and those with myopia are not susceptible to this refractive shift. The authors' RK data suggest that the time since surgery and the amount of surgery are related to the degree of hyperopic shift during altitude exposure.

Preliminary results of photorefractive keratectomy in active-duty United States Navy personnel.

PURPOSE: To evaluate the safety, efficacy, and quality of vision after photorefractive keratectomy (PRK) in active-duty military personnel. METHODS: Photorefractive keratectomy (6.0-mm ablation zone) was performed on 30 navy/marine personnel(-2.00 to -5.50 diopters [D]; mean, -3.35 D). Glare disability was assessed with a patient questionnaire and measurements of intraocular light scatter and near contrast acuity with glare. RESULTS: At 1 year, all 30 patients had 20/20 or better uncorrected visual acuity with no loss of best-corrected vision. By cycloplegic refraction, 53% (16/30) of patients were within +/- 0.50 D of emmetropia and 87% (26/30) were within +/- 1.00 D. The refraction (mean +/- standard deviation) was +0.45 +/- 0.56 D (range, -1.00 to 1.63 D). Four patients (13%) had an overcorrection of more than 1 D. Glare testing in the early (1 month) postoperative period demonstrated increased intraocular light scatter (P<0.01) and reduced contrast acuity (with and without glare, (P<0.01). These glare measurements statistically returned to preoperative levels by 3 months (undilated) and 12 months (dilated) postoperatively. Two patients reported moderate to severe visual symptoms (glare, halo, night vision) worsened by PRK. One patient had a decrease in the quality of night vision severe enough to decline treatment in the fellow eye. Intraocular light scatter was increased significantly (>2S D) in this patient after the procedure. CONCLUSIONS: Photorefractive keratectomy reduced myopia and improved the uncorrected vision acuity of all patients in this study. Refinement of the ablation algorithm is needed to decrease the incidence of hyperopia. Glare disability appears to be a transient event after PRK. However, a prolonged reduction in the quality of vision at night was observed in one patient and requires further study.

Vasopressin inhibits diuresis induced by water immersion in humans.

We tested the hypothesis that 1-desamino-8-D-arginine vasopressin (DDAVP), a V2-receptor agonist, could inhibit the diuresis induced by water immersion in humans. Water and electrolyte excretion, plasma atrial natriuretic factor concentration, and plasma aldosterone concentration were measured initially and after 3 h of water immersion in 13 healthy sodium-replete men given either placebo or 20 micrograms of intranasal DDAVP. Guanosine 3',5'-cyclic monophosphate and urea excretion and urine osmolality were also determined. DDAVP inhibited the diuresis induced by water immersion in men: 758 +/- 168 (SE) ml/3 h in the placebo group vs. 159 +/- 28 ml/3 h in the DDAVP group (P less than 0.05). After 3 h of water immersion, plasma atrial natriuretic factor concentrations were increased from 11 +/- 2 to 20 +/- 4 pg/ml in the placebo group and from 14 +/- 2 to 33 +/- 4 pg/ml in the DDAVP group (P less than 0.05). Plasma aldosterone concentrations were decreased from 98 +/- 18 to 45 +/- 6 pg/ml in the placebo group (P less than 0.05) and from 54 +/- 17 to 25 +/- 5 pg/ml in the DDAVP group (P less than 0.05). Despite these changes in aldosterone and atrial natriuretic factor concentrations, which should increase sodium excretion, DDAVP decreased the natriuresis induced by water immersion in humans: 56 +/- 8 meq Na+/3 h in the placebo group vs. 36 +/- 6 meq Na+/3 h in the DDAVP group (P less than 0.05). DDAVP may be used to prevent the diuresis associated with central redistribution of blood volumes that occur during water immersion.(ABSTRACT TRUNCATED AT 250 WORDS)