Glucose challenge test screening for prediabetes and undiagnosed diabetes.

AIMS/HYPOTHESIS: Diabetes prevention and care are limited by lack of screening. We hypothesised that screening could be done with a strategy similar to that used near-universally for gestational diabetes, i.e. a 50 g oral glucose challenge test (GCT) performed at any time of day, regardless of meal status, with one 1 h sample. METHODS: At a first visit, participants had random plasma and capillary glucose measured, followed by the GCT with plasma and capillary glucose (GCTplasma and GCTcap, respectively). At a second visit, participants had HbA(1c) measured and a diagnostic 75 g OGTT. RESULTS: The 1,573 participants had mean age of 48 years, BMI 30.3 kg/m(2) and 58% were women and 58% were black. Diabetes (defined by WHO) was present in 4.6% and prediabetes (defined as impaired glucose tolerance [2 h glucose 7.8-11.1 (140-199 mg/dl) with fasting glucose

Biochemical features of urinothorax.

In three patients with obstructive uropathy and retroperitoneal urine collections, rapidly accumulating pleural effusions developed. The diagnosis of urinothorax was confirmed when chemical analysis of pleural fluid disclosed higher creatinine concentrations than found in simultaneously obtained serum samples. Similar determinations made in 71 specimens from control patients with pleural effusions showed that pleural creatinine concentration did not exceed the serum level in other conditions. We conclude that elevated pleural fluid creatinine level is specific for the diagnosis of urinothorax. Low pleural fluid glucose concentration may also be seen in these patients.

Laboratory evaluation of new reusable blood glucose sensor.

An enzyme-electrode sensor designed specifically for pocket-portable self-monitoring of blood glucose is described. The sensing device in this instrument is unique because it is reusable for at least 30 days, at which time it is easily replaced by placing a new enzyme-membrane cartridge over the electrode. As little as 7 microliters of undiluted whole blood, plasma, or serum is applied directly to the sensor, and glucose is automatically determined in 30 s. No manual timing or wiping step is required after sample application. On eight production instruments, plasma glucose concentration was determined (n = 20) at 57, 125, 246, and 347 mg/dl. The average coefficient of variation for the 80 determinations for each instrument ranged from 2 to 5%, averaging 3.7%. The instrument is inherently linear, independent of hematocrit, and without oxygen limitation when dissolved oxygen concentration is greater than 35 mmHg. No interferences were found from plasma constituents, heparin, or acetaminophen.

Diagnostic value of ophthalmologic findings in myotonic dystrophy: comparison with risks calculated by haplotype analysis of closely linked restriction fragment length polymorphisms.

To determine diagnostic value of lens opacities in myotonic dystrophy (DM), we examined 98 at-risk members of 9 DM kindreds. Haplotype analysis of restriction fragment length polymorphisms (RFLPs) using ApoC2, CKMM, and pEFD4.2 supported the diagnosis of DM in 33 and excluded the diagnosis in 51 members. The sensitivities of bilateral iridescent lens opacities, posterior cortical lens opacities, orbicularis oculi weakness, low intraocular pressure, ptosis, and ocular myotonia were 46.7, 50.0, 60.6, 59.3, 51.5, and 3.0%, while their specificities were 100.0, 100.0, 98.0, 94.1, 96.1, and 100.0%, respectively. A peripheral pigmentary degeneration and central macular lesions of retina were not found on indirect fundoscopy. In 86.2% of DM patients, bilateral iridescent lens opacities, posterior cortical lens opacities, or both were present. Unilateral iridescent lens opacities occurred in only 3 of our DM patients, and 2 of non-DM relatives showed a few unilateral iridescent particles. Posterior cortical lens opacities in DM patients always affected both eyes in this series. We conclude that 1) bilateral iridescent lens opacities and posterior cortical lens opacities are highly specific for DM and useful for establishing clinical diagnosis of DM, 2) unilateral iridescent lens opacities are infrequent in DM and are seen in some non-DM members, and 3) ocular myotonia and clinical retinopathies are rare in DM.

Epidemiological evidence for the disruption of ionized calcium homeostasis in the elderly.

Ionized calcium (Ca2+), phosphate, albumin, total calcium, and pH measurements taken from participants in a large population-based epidemiological study were examined to determine the change in physiological variation with age for persons over 43 years old. Only Ca2+ showed a statistically significant increase in SD with age (p < 0.0001). The Ca2+ coefficients of variation (CV) increased from 2.92% in the youngest age group (43-54 years) to 3.69% in the oldest age group (75-86 years of age). In females, the increase in Ca2+ variability was nearly complete by age 55. Males also showed a significant (p = 0.006) increase in SD between the 43-54 age group and the 55-64 age group, however, Ca2+ variability did not plateau after age 55 in men as it did in women. In the 43-54 (p = 0.04) and 55-64 (p = 0.03) age group men showed significantly better physiological control of Ca2+ than women. Phosphate showed a slight decrease in CV with age. These data suggest that Ca2+ homeostasis is disrupted in the same age groups that are most vulnerable to osteoporosis.

Surgical management of advanced ocular adnexal amyloidosis.

Ocular adnexal amyloidosis is characterized by amyloid deposition within the deep connective tissue layers of the eyelids, conjunctiva, and anterior orbit. Management of advanced cases has traditionally been unsatisfactory, with either no surgery offered because of fear of hemorrhage or an en bloc resection performed of the entire involved area. We present two cases of advanced periorbital amyloidosis successfully managed by preserving the anatomic planes of the eyelids and meticulously debulking the deposits with a spooned curette. Lax eyelid tendons and aponeuroses were simultaneously repaired, and no sacrifice of eyelid tissues was necessary. One patient remained asymptomatic for 2 years after surgery before developing early reaccumulation in the lower eyelids. The other patient required additional eyelid debulking and ptosis revision 8 months after surgery, but was in stable condition at follow-up 2 years after surgery. This technique offers safe, easily repeatable, nondestructive treatment for advanced periocular amyloidosis.

Axial myopia increases the risk of retinal complications after neodymium-YAG laser posterior capsulotomy.

We conducted a retrospective analysis of Q-switched neodymium-YAG laser capsulotomies performed in 122 eyes between April 1984 and June 1987. Retinal complications occurred in 3 (2.5%) of 121 eyes followed up for 1 year and in 2 (3.6%) of 55 eyes followed up for 2 years. Four eyes developed rhegmatogenous retinal detachments and 1 developed an acute symptomatic retinal tear. No patients developed clinical cystoid macular edema (visual acuity 20/30 or worse). These retinal complications were significantly correlated with axial myopia, preexisting vitreoretinal disease, male gender, younger age, vitreous prolapse into the anterior chamber, and spontaneous extension of the capsulotomy.

Acute and chronic conjunctivitis due to over-the-counter ophthalmic decongestants.

OBJECTIVE: To describe patterns of conjunctivitis caused by ophthalmic decongestants. DESIGN: Case series. SETTING: Outpatient eye clinic. PATIENTS: We selected patients with conjunctival inflammation who were using nonprescription decongestant eyedrops, who had no other cause for conjunctivitis, and whose conditions improved after discontinuing the incriminated preparations. MAIN OUTCOME MEASURES: Clinical characteristics of conjunctival inflammation and time to resolution of symptoms and signs after discontinuing the use of eyedrops. RESULTS: Seventy patients (137 eyes) were identified. Preparations containing the vasoconstrictors naphazoline, tetrahydrozoline, or phenylephrine were associated with 3 clinical patterns of conjunctivitis: conjunctival hyperemia (50 cases), follicular conjunctivitis (17 cases), and eczematoid blepharoconjunctivitis (3 cases). Decongestants were used daily for a median of 3 years (range, 8 hours to 20 years) prior to presentation. The median time to resolution of symptoms and signs was 4 weeks (range, 1-24 weeks), and patients remained asymptomatic for a median follow-up of 6 months (range, 0-12 years). CONCLUSION: Nonprescription decongestant eyedrops can produce acute and chronic forms of conjunctivitis by pharmacological, toxic, and allergic mechanisms. Once recognized, conjunctival inflammation often takes several weeks to resolve.

Wide variation in serum anion gap measurements by chemistry analyzers.

The traditional anion gap [AG = Na-Cl-(total CO2)] mean value of 12 mEq/L was established during the 1970s with analyzer methods that are no longer used widely. No studies have systematically compared mean AG values from analyzers in current use. We used data from healthy subjects obtained from 27 clinical laboratories, 5 manufacturers, and 8 publications to compute mean AG values from 1970s analyzers and 8 current analyzers. We also compared mean AG values by evaluating Na, Cl, and total CO2 data from the College of American Pathologists Chemistry Surveys (1990-1996). Data from healthy subjects showed that overall mean AG values of the 9 analyzers ranged from 5.9 to 12.4 mEq/L. The pooled (i.e., average) AG SD was 2.3 mEq/L. We then used the data of the Surveys and the mean value from 1 analyzer to compute predicted mean values for the other 7 current analyzers. Almost all mean AG values predicted from the Surveys agreed (within 1.5 mEq/L) with mean values from healthy subjects. These results show that mean values of analyzers vary widely, indicating that analytic bias strongly influences the AG. The results should be a useful guide for the AG measurements that can be expected from different analyzers.

Scleral flap surgery for modification of corneal astigmatism.

We performed resections and recessions of scleral flaps on human cadaver eyes in order to measure the induced change in keratometric astigmatism. We prepared 3-mm scleral flaps that were 3, 5, 7, or 10 mm long and resected or recessed these flaps up to 1 mm in 0.25-mm increments. Scleral flap resection resulted in up to 10.1 D of net corneal steepening along the meridian of the incision. Scleral flap recessions resulted in up to 7.7 D of net corneal flattening along the meridian of the incision; the effect increased with increasing flap length in the recessed eyes. There was a tendency toward mean corneal flattening with resections and mean corneal steepening with recessions.

Refractive complications of cataract surgery after radial keratotomy.

Four patients underwent cataract extraction with posterior chamber lens implantation several years after radial keratotomy. All four patients experienced an initial hyperopic shift caused by an early postoperative corneal flattening of greater than or equal to 1 diopter. This flattening partially regressed, leaving the patients with a mean of 0.42 diopter of persistent corneal flattening. We found the Binkhorst and the Holladay intraocular lens calculation formulas to be more accurate than the SRK II for these patients. Corneal curvature measured with the keratometer was less accurate for intraocular lens calculations than was a value derived by subtracting the refractive change induced by the radial keratotomy from the patients' keratometric measurements obtained before radial keratotomy.

Comparison of changes in manifest refraction and corneal power after photorefractive keratectomy.

PURPOSE: To determine which corneal curvature values most closely correlate to change in manifest refraction after excimer laser photorefractive keratectomy. METHODS: In a prospective study at the Cullen Eye Institute, excimer laser photorefractive keratectomy was performed on 27 eyes of 27 patients (mean age, 38.07+/-6.65 years). Preoperative refractive errors ranged from -2.25 diopters to -8.75 diopters (mean, -5.74+/-2.09 diopters). Preoperatively and 1 month postoperatively, we determined the spherical equivalent of the subjective manifest refraction (corrected for a 12-mm vertex distance) and measured corneal power using standard keratometry (Bausch & Lomb Keratometer; Rochester, New York) and computerized videokeratography (EyeSys Corneal Analysis System; Premier Laser Systems Inc, Houston, Texas). We collected 15 corneal values: standard keratometry and 14 computerized videokeratography values calculated using the axial, instantaneous, and refractive formulas. All calculations were performed with 1.3375 and 1.376 for the refractive index of the cornea. For each of the corneal values, we subtracted the change in corneal power from the change in manifest refraction and calculated for this difference the means, SDs, correlations, and regressions. RESULTS: Mean differences between change in refraction and change in corneal power were lower when for a refractive index of 1.376 than for 1.3375, were lowest for the most central measurement points, and displayed a high SD. A value of 1.408 for the refractive index would be required to optimize the correlation between change in manifest refraction and effective refractive power of the central 3 mm of the cornea. CONCLUSIONS: For individual patients who have undergone photorefractive keratectomy, changes in corneal values determined by computerized videokeratography or by standard keratometry do not reliably predict change in manifest refraction.

Stability of vision during space flight in an astronaut with bilateral intraocular lenses.

PURPOSE: To report excellent and stable vision in an astronaut during space flight after bilateral cataract surgery with intraocular lenses. METHODS: A 60-year-old physician mission specialist astronaut developed cataracts and underwent phacoemulsification with insertion of one-piece polymethylmethacrylate intraocular lenses that had 6-mm optics bilaterally. Several months later, he flew on a space shuttle mission. Ocular examinations were performed before and after the mission, and the patient was questioned about visual changes during flight. RESULTS: Ocular examinations demonstrated stable bilateral posterior chamber intraocular lenses. Our subject reported excellent vision during liftoff, 18 days of microgravity, changes in cabin pressure, and reentry. CONCLUSION: Results suggest that intraocular lenses are safe, effective, and well tolerated during space flight.

A comparison of corneal endothelial changes after use of Healon or Viscoat during phacoemulsification.

We conducted a prospective, randomized trial comparing the endothelial protective effects of Healon (Kabi Pharmacia Ophthalmics, Inc., Monrovia, California) and Viscoat (Alcon Surgical, Inc., Ft. Worth, Texas) in 59 eyes of 59 patients undergoing iris-plane or posterior-chamber phacoemulsification with posterior-chamber lens implantation. We evaluated postoperative central and superior changes in corneal thickness and corneal endothelial cell density, coefficient of variation in cell size, and percentage of hexagons. In the overall series, at one day postoperatively, corneal thickness increased 17% centrally and superiorly in eyes receiving Healon compared to 12% centrally and 11% superiorly in eyes receiving Viscoat (P < .05). Sixteen weeks postoperatively, superior endothelial cell loss was 11.6% in eyes receiving Healon compared to 2.1% in eyes receiving Viscoat (P < .01). In the iris-plane phacoemulsification group, superior cell loss at week 16 was 13.8% in eyes receiving Healon and 0.5% in eyes receiving Viscoat (P < .04). In the posterior-chamber phacoemulsification group, there were no significant differences between the Healon and Viscoat subgroups. Comparing the surgical techniques, in the Healon group, central cell loss at week 16 was 13.8% in the iris-plane phacoemulsification subgroup and 0.6% in the posterior-chamber phacoemulsification subgroup (P < .03), and coefficient of variation in cell size increased 3.7% in the iris-plane subgroup and decreased 6.8% in the posterior-chamber subgroup (P < .04). In the Viscoat group, there were no significant differences between surgical techniques at week 16. Viscoat provided greater corneal endothelial protection than Healon during iris-plane phacoemulsification. In eyes receiving Healon, posterior-chamber phacoemulsification resulted in less corneal endothelial trauma than the iris-plane technique.

Comparative corneal topography and refractive variables in monozygotic and dizygotic twins.

PURPOSE: To investigate the role of heredity in determining corneal shape, axial length, and overall refractive error. METHODS: Twenty monozygotic and 19 dizygotic twin pairs, age 12 to 73 years, were enrolled in the study. Zygosity was determined by physical similarity and by responses to questions adapted from surveys. Two twin pairs were excluded because of undetermined zygosity and one pair because of keratoconus (both siblings). Refractive error was determined by an automated refractor. Manifest refraction was also recorded, as well as cycloplegic refraction in subjects under age 18 years. Corneal topography data and manual keratometer readings were also obtained. Axial lengths were determined by A-scan ultrasound. Data were analyzed by Student t tests only in the right eye. Left-eye data were comparable for all variables. RESULTS: Mean intrapair difference in refractive error (spherical equivalent) was less for monozygotic than for dizygotic twins (RE: 0.41 vs 1.53; P = .001). Mean intrapair difference in axial length was less for monozygotic twins (RE: 0.39 vs 0.76 mm; P = .031). Corneal topography data (power and meridian) in all zones (3, 5, and 7 mm) also showed smaller mean differences among monozygotic pairs than dizygotic, but the difference was statistically significant only for the 5-mm zone. In addition, most Holladay Diagnostic Summary variables that were studied did not show any statistically significant differences. CONCLUSIONS: Axial length and overall refractive error have a significant genetic basis. Corneal topography data appear to have other overriding determining factors for several of the variables studied.

A prospective multicenter clinical trial to evaluate the safety and effectiveness of the implantable miniature telescope.

PURPOSE: To evaluate the safety and preliminary efficacy of a novel visual prosthetic device, the Implantable Miniature Telescope, IMT (by Dr Isaac Lipshitz) (IMT), in a phase I trial in patients with significant bilateral central vision impairment from late-stage age-related macular degeneration (AMD). The IMT is designed to reduce the relative size of the scotoma by rendering enlarged (threefold) central visual field images over the central and peripheral retina. DESIGN: Prospective, multicenter, open-label clinical trial. METHODS: In this prospective, multicenter phase I trial, 14 patients aged 60 or older with bilateral geographic atrophy or disciform scar AMD, cataract, and best-corrected visual acuity (BCVA) between 20/80 and 20/400 had an IMT implanted in one eye. Distance and near BCVA, endothelial cell density, and quality of life, measured as activities of daily life (ADL), were evaluated preoperatively and postoperatively. RESULTS: At 12 months, 10 (77%) of 13 patients gained 2 more lines of either distance or near BCVA, and eight (62%) of 13 patients gained 3 or more lines in either distance or near BCVA. Mean endothelial cell density decreased by 13%. All adverse events resolved without sequelae. ADL scores improved in the majority of patients. CONCLUSION: The results of this phase I trial support further evaluation of the IMT in a larger study population with late-stage AMD. A phase II/III trial is in progress.

Photoastigmatic refractive keratectomy in myopes. Nidek US Investigators Group.

PURPOSE: Photoastigmatic refractive keratectomy (PARK) was studied in a multi-center clinical trial. The Nidek EC-5000 excimer laser was evaluated for its effect on refraction, visual acuity, and safety measures as part of a U.S. Food and Drug Administration (FDA) regulated study. METHODS: Eight U.S. centers enrolled adults with eyes having refractive astigmatism up to 4.00 D and a myopic spherical equivalent refraction up to -8.00 D. Results are reported for 749 eyes of 486 patients with at least 6 months follow-up. The rectangular beam scanning Nidek EC-5000 used a 5.5-mm-diameter treatment zone, a 7.0-mm-diameter peripheral blend zone, and a 40 Hz pulse rate for surface treatment of myopic astigmatism. Nomogram corrections to machine settings were required to achieve the desired results. RESULTS: Preoperative average spherical equivalent refraction of -4.90+/-1.74 D was reduced to -0.02+/-0.79 D at 6 months. Refractive stability was established at 3 months. Over 62% of eyes were within +/-0.50 D of desired correction at 6 months, with over 86% within +/-1.00 D. Uncorrected visual acuity improved by an average of 10 Snellen lines; over 64% of eyes saw 20/20 or better uncorrected and over 93% saw 20/40 or better uncorrected at 6 and 12 months. PARK treatment effectively reduced astigmatism with little average axis error or magnitude error. Corneal haze and safety concerns were minimal. CONCLUSIONS: Photoastigmatic refractive keratectomy using the Nidek EC-5000 excimer laser provided significant reduction of myopia and astigmatism, with minimal complications.

Histologic changes and wound healing response following 10-pulse noncontact holmium:YAG laser thermal keratoplasty.

BACKGROUND: Noncontact holmium:YAG laser thermal keratoplasty (Ho:YAG LTK) is a promising new technology for correction of hyperopia and astigmatism. We studied the acute histologic changes and wound healing response following Ho:YAG LTK performed with treatment parameters encompassing those used in clinical studies. METHODS: We performed 10-pulse noncontact Ho:YAG LTK on three human corneas 1 day before their removal at penetrating keratoplasty and on six New Zealand white rabbit corneas followed for up to 3 months. Tissues were studied with light and transmission electron microscopy and immunohistochemistry. RESULTS: The amount of acute tissue injury increased according to the pulse radiant energy. In human corneas, changes in the irradiated zones included epithelial cell injury and death, loss of fine filamentous structure in Bowman's layer, disruption of stromal lamellae, and keratocyte injury and death. In the rabbit corneas, similar acute changes were noted. By 3 weeks, epithelial hyperplasia and stromal contraction were present. Wound healing in the rabbits included repair of the epithelial attachment complex, keratocyte activation, synthesis of type I collagen, partial restoration of stromal keratan sulfate and type VI collagen, and retrocorneal membrane formation. CONCLUSIONS: Noncontact Ho:YAG LTK produces acute epithelial and stromal tissue changes and in rabbit corneas stimulates a brisk wound healing response.

Glare and contrast sensitivity testing in cataract patients.

I measured contrast sensitivity and glare in 51 cataract patients who had Snellen visual acuities of 20/60 or better. The VCTS contrast sensitivity plates, the Miller-Nadler glare tester, Baylor visual function tester, and the Stereo Optical glare tester were used. Patients indicated that the Baylor visual function tester most closely reproduced their daytime glare symptoms and that the Stereo Optical glare tester most closely reproduced their nighttime glare symptoms. Scores on the Stereo Optical glare tester and VCTS contrast sensitivity chart statistically were most strongly correlated with patients' complaints and the severity of their lens opacities. Contrast sensitivity and glare testing are important adjuncts in evaluating patients who have visual complaints and yet have good Snellen acuities.