Distribution and determinants of intraocular pressure in a normal pediatric population

PURPOSE: To examine the intraocular pressure (IOP) of a normal pediatric population under topical anesthesia without sedation and its correlation with other ocular parameters. SUBJECTS AND METHODS: The IOP of 810 eyes of 405 patients with ages ranging from 0 to 12 years was measured using the Perkins applanation tonometer. Cooperative patients also underwent pachymetry, refraction, and biometry measurements. RESULTS: The mean (+/- standard deviation) age was 6.68 (+/- 3.28) years, with a mean (+/- standard deviation) IOP of 12.02 (+/- 3.74) mm Hg. IOP showed an increasing trend with age (correlation coefficieit [r] = 0.49) and tended to approach adult levels by 12 years of age. The IOP correlated directly with refraction (r = 0.69) and pachymetry (r = 0.39) and inversely with axial length (r = -0.1). CONCLUSIONS: The IOP in children is much lower than that in adults. It was noted to increase with age, hyperopia, and corneal thickness and was inversely proportional to axial length.     

Decreased central corneal thickness in children with Down syndrome

PURPOSE: A cross-sectional, masked, case-control study was undertaken to investigate whether central corneal thickness is affected in children with Down syndrome and to focus on its clinical significance. PARTICIPANTS AND METHODS: Twenty-eight children with Down syndrome (15 boys and 13 girls) aged 5 to 15 years and 20 age-matched and gender-matched healthy control subjects (11 boys and 9 girls) from a similar ethnic background were enrolled in the study. Central corneal thickness was measured by ultrasound pachymetry. Only the right eye of each child in each group was included in the statistical analysis. The Mann-Whitney U test was used and a P value of less than .05 was considered significant. RESULTS: The mean ages of the children with Down syndrome (9.28 +/- 3.47 years) and the healthy control subjects (8.75 +/- 3.30 years) were comparable (P > .05). Central corneal thickness values were below 500 microm in 19 (67.8%) of the 28 children with Down syndrome, 4 of which were less than 450 microm. However, all central corneal thickness measurements in the control eyes were more than 500 microm. The mean central corneal thickness in the children with Down syndrome was significantly (P < .001) less (488.39 +/- 39.87 microm) than that in the healthy control subjects (536.25 +/- 20.70 microm). Mean keratometric values were significantly (P < .001) higher in the eyes of the children with Down syndrome (46.35 +/- 1.28 D) than in the eyes of the control subjects (43.32 +/- 1.15 D). CONCLUSIONS: Children with Down syndrome had a decreased central corneal thickness compared with healthy control subjects. Decreased central corneal thickness may give an artificially low intraocular pressure measurement by applanation tonometry. Central corneal thickness must be considered when developing approaches for keratorefractive treatment of patients with Down syndrome.     

The effect of different doses of ketamine on intraocular pressure in anesthetized children

BACKGROUND: When used for induction of anesthesia, ketamine usually increases intraocular pressure (IOP). However, the effect of low doses of ketamine, which are used for parental separation in children, is unknown. We studied the effect of two different doses of ketamine on IOP in anesthetized children. METHODS: Forty children age 1 to 6 years who met American Society of Anesthesiologists physical status I criteria scheduled to undergo surgery were randomly selected to receive either an induction dose (6 mg/kg) or a low dose (3 mg/kg) of ketamine intramuscularly. Anesthesia was induced and maintained with halothane, and ketamine was injected 10 minutes after induction. Intraocular pressure was measured using a Perkins applanation tonometer before ketamine administration and every 5 minutes thereafter for 20 minutes by an observer who was unaware of the ketamine dose used. 10.8 +/- 2.2 mm Hg to 12.6 +/- 2.8 mm Hg at 5 minutes and 11.9 +/- 2.5 mm Hg at 10 minutes after administration of ketamine in the induction-dose group. There was no significant change in IOP after administration of ketamine in the low-dose group. Intraocular pressure was significantly higher in the induction-dose group compared to the low-dose group at 5 minutes after administration of ketamine. More patients in the induction-dose group had postoperative airway obstruction and sedation than in the low-dose group. CONCLUSIONS: In children anesthetized with halothane, ketamine had a dose-dependent effect on IOP, with 6 mg/kg of the drug causing a small increase in IOP at 5 to 10 minutes and 3 mg/kg not altering the IOP. The higher dose of ketamine also was associated with an increased incidence of postoperative complications.     

Intraocular pressure in children up to five years of age

We established a value scale (Figure) of IOP for children without glaucoma. Under the age of 4 months the IOP was measured with topical anesthesia; halothane anesthesia was used in children from 4 months to 5 years. In 30 children under the age of 4 months the IOP is 8.4 +/- 0.6 mm Hg. In 44 children from 4 months to 5 years, the IOP measured under halothane general anesthesia is 7.8 +/- 0.4 mm Hg at the age of 1 year, and it gradually increases by about 1 mm Hg per year of age to 11.7 +/- 0.6 mm Hg at the age of 5 years.     

Ahmed valve surgery for refractory pediatric glaucoma: a report of 52 eyes

PURPOSE: To describe the results of Ahmed valve surgery for refractory pediatric glaucoma. PATIENTS AND METHODS: We performed a retrospective review of patients younger than 18 years of age who had Ahmed valve surgery from November 1994 to January 2003. Success was defined as a reduction of the intraocular pressure (IOP) to 22 mm Hg or lower with or without medications at the last two follow-up visits, no additional glaucoma surgery, and no visually significant complications. RESULTS: There were 52 eyes of 41 patients. The two most common diagnoses were congenital glaucoma (38.5%) and aphakic glaucoma (36.5%). The mean number of glaucoma surgeries before Ahmed valve implantation was 1.7 +/- 1.7. The mean age at the time of implantation was 4.9 +/- 6.5 years. The mean IOP decreased from 38.1 +/- 6.4 mm Hg to 20.7 +/- 8.2 mm Hg at last follow-up. The final visual acuity was improved or within one Snellen line in 81.5% of the eyes. Cumulative probabilities of success were 85.1%, 63.2%, 51.7%, and 41.8% at 1, 2, 3, and 4 years, respectively. The mean postoperative follow-up period or time to failure for all patients was 2.2 +/- 1.8 years (range, 3 months to 7.5 years). CONCLUSIONS: The Ahmed valve was found to be useful in the management of refractory pediatric glaucoma. Although our success rates were similar to those observed in adults, the rates of certain post-operative complications were different.     

Age and racial variation in central corneal thickness of preschool and school-aged children

PURPOSE: The purpose of this study was to determine variations in central corneal thickness (CCT) of preschool and school-aged African American and white children. Secondary aims were to assess possible correlations between CCT measurements and gender, axial length, intraocular pressure (IOP), family history of glaucoma, or history of prematurity. METHODS: Contact ultrasound was used to measure CCT and axial length in 76 white and 60 African American children between the ages of 7 months and 18 years. A questionnaire was completed by the parents or guardians, including medical and family history. Statistically significant associations and differences were assessed using the independent t test, analysis of variance, and linear regression. All associations were defined as significant when the alpha value was less than 0.05 (two-tailed). RESULTS: Mean CCT was thinner in African American children (535 +/- 35 microm) compared to white children (559 +/- 38 microm) (P < .001). The corneal thickness in children ages 10 to 18 years was significantly higher than in all other age groups in both African American (P = .03) and white (P < .005) children. No association was found between CCT and gender, axial length, IOP, or family history of glaucoma. Premature children had thinner CCT (536 +/- 40 pm) than full-term children (552 +/- 38 microm) (P = .009). CONCLUSIONS: African American children have a thinner CCT compared to white children at all ages. Children of both racial groups have an increasing value of CCT with increasing age after approximately age 10 years. Children born prematurely have a thinner CCT than full-term children.     

Comparison of auscultatory and oscillometric blood pressures

OBJECTIVE: To study the differences in blood pressure readings between the auscultatory and oscillometric (Dinamap model 8100; Critikon, Tampa, Fla) methods. DESIGN: Survey of 2 blood pressure instruments. SETTING: Public schools. PARTICIPANTS: Seven thousand two hundred eight schoolchildren aged 5 through 17 years. MAIN OUTCOME MEASURE: Blood pressure levels. RESULTS: For all children combined, Dinamap systolic pressure readings were 10 mm Hg higher (95% confidence interval, -4 to 24 mm Hg) than the auscultatory systolic pressure readings. Dinamap diastolic pressure readings were 5 mm Hg higher (95% confidence interval, -14 to 23 mm Hg) than the auscultatory Korotkoff phase V diastolic pressure readings. CONCLUSION: These findings preclude the interchange of readings by the 2 methods. Caution must be exercised in the diagnosis of hypertension when an automated device is used.     

Cataract and ocular hypertension in children on inhaled corticosteroid therapy

PURPOSE: To ascertain the incidence of posterior subcapsular cataract and ocular hypertension in a cohort of children < or = 12 years on inhaled steroid therapy. PATIENTS AND METHODS: In this prospective study, a detailed history regarding corticosteroid therapy was obtained for children attending an asthma clinic. The presence and type of lens changes (cataract) was recorded and intraocular pressure (IOP) was measured. The children underwent another eye examination 2 years later. RESULTS: Ninety-five patients were enrolled in the study. Mean patient age was 7 +/- 3 years, and mean duration of inhaled steroid therapy was 2 +/- 1 years. Thirty-six percent of patients received inhaled steroids exclusively, 61% received inhaled steroids with a short course of oral steroids, and 3% received inhaled steroids with a long course of oral steroids. Only 3 (3%) patients had cortical changes that were not visually significant, and none had posterior subcapsular or nuclear cataract. There was no significant differences between children with cataract and those without cataract with respect to age; duration of asthma; and duration, average daily dose, and cumulative dose of inhaled steroids. IOP ranged from 11 to 20 mm Hg (mean, 16 +/- 3 mm Hg). None of the children had ocular hypertension or glaucoma. Ninety patients underwent eye examination 2 years later; none was found to develop posterior subcapsular cataract or increased IOP. CONCLUSION: This study indicates the use of inhaled steroids in children with asthma is probably safe as far as not inducing posterior subcapsular cataract or ocular hypertension.     

Normative arm and calf blood pressure values in the newborn

Indirect BP measurement was obtained in the right upper arm in 219 healthy newborn infants with the Dinamap monitor and was compared with values obtained from the calf to establish normative BP values and to help establish a diagnosis of hypertension and coarctation of the aorta in the newborn. There were 174 Mexican-Americans (79.5%), 33 whites (15.0%), and 12 blacks (5.5%). The width of the BP cuff was selected to be 0.4 to 0.5 times the circumference of the extremities. Three supine position readings of BPs and heart rate were obtained from each site and were averaged for statistical analyses. Mean arm BP values (+/- SD) of the neonate less than 36 hours of age were 62.6 +/- 6.9/38.9 +/- 5.7 mm Hg (48.0 +/- 6.2 mm Hg). Neonates older than 36 hours had slightly but significantly (P less than .05) greater values (4 to 6 mm Hg) than did infants younger than 36 hours of age. Active neonates had values 6 to 10 mm Hg greater than quiet neonates (P less than .05). BP values in the calf obtained with the same-sized cuff were almost identical with those obtained from the arm. Differences in consecutively obtained arm and calf BPs (arm values minus calf values) were 1.1 +/- 7.7 mm Hg systolic, -0.01 +/- 6.2 mm Hg diastolic, and 0.9 +/- 6.9 mm Hg mean pressures. Mean heart rate (+/- SD) of neonates less than 36 hours of age was 129.4 +/- 13.2 beats per minute and that of neonates older than 36 hours of age was 139.4 +/- 14.1 beats per minute.(ABSTRACT TRUNCATED AT 250 WORDS)     

Accuracy of blood pressure measurement by the Dinamap monitor in infants and children

Indirect BPs measured by the Dinamap monitor, an oscillometric device, and the conventional auscultatory method were compared with the direct radial artery pressure in infants and children. There were 29 patients in the Dinamap group with a median age of 18 months (ranges 1 month to 16 years) and 20 patients in the auscultatory group with a median age of 3.5 years (ranges 3 months to 16 years). The direct radial artery pressures were recorded on a strip chart and the ranges of pressures were obtained for systolic, diastolic, and mean pressures. The range of the direct readings was converted to a weighted single reading, and comparisons were made between the direct and indirect readings. The linear regression equation between the direct (x) and the Dinamap (y) readings (with correlation coefficient) was y = 1.05x - 5.36 (r = .97) for systolic, y = 1.10x - 4.65 (r = .903) for diastolic, and y = 1.06x - 4.21 (r = .917) for mean pressures. The linear regression equation (with correlation coefficient) for the auscultatory pressure was y = 1.60x - 68.23 (r = .872) and y = 1.38x - 16.47 (r = .874) for diastolic pressures. The error was defined as the indirect reading minus the direct reading. The mean error +/- SD was -0.24 +/- 3.26 for systolic, 1.28 +/- 4.74 for diastolic, and 0.10 +/- 4.56 mm Hg for mean pressures by the Dinamap method. It was -1.65 +/- 6.68 for systolic, and 8.70 +/- 5.97 for diastolic pressures by the auscultatory method.(ABSTRACT TRUNCATED AT 250 WORDS)     

Correlations between the intrauterine metabolic environment and blood pressure in adolescent offspring of diabetic mothers

OBJECTIVE: To investigate associations between maternal diabetes and blood pressure (BP), obesity, impaired glucose tolerance, and serum lipids in offspring and whether these parameters correlate with metabolism during pregnancy. STUDY DESIGN: Body mass index, BP, serum glucose, and insulin during an oral glucose tolerance test, and lipid concentrations were measured in 99 offspring of diabetic mothers (ODM) and 80 members of a control group. RESULTS: ODM were more obese (body mass index 22.5 +/- 5.6 vs 20.3 +/- 4.0 kg/m(2)) and had higher systolic (8 mm Hg) and mean arterial BP (4 mm Hg) but similar diastolic BP compared with the control group. ODM had higher 2-hour glucose (6.6 +/- 1.3 vs 5.7 +/- 0.9 mmol/L) and insulin (580 +/- 544 vs 377 +/- 239 pmol/L) concentrations but lower fasting concentrations of low-density lipoprotein (2.54 +/- 0.67 vs 2.82 +/- 0.70 mmol/L) and total cholesterol (4.01 +/- 0.80 vs 4.40 +/- 0.78 mmol/L). In both groups body mass index, triglycerides, and fasting and 2-hour glucose concentrations showed correlations with BP measurements. Fasting insulin was correlated with BP readings only in the ODM. Correlations were found between second- and third-trimester maternal free fatty acid concentrations and diastolic and mean arterial BP. Third-trimester beta-hydroxybutyrate was correlated with mean arterial BP. CONCLUSIONS: In ODM, abnormalities in weight and glucose tolerance are associated with abnormal maternal metabolism. Higher BP is an additional abnormality associated with fetal overnutrition.     

In vivo evaluation of monopolar intravascular PO2 electrodes.

Ten intravascular electrodes were evaluated on ten rabbits. The mean stabilized time of 118 +/- 52 min was excessively long for clinical use. The in vitro cal factor was not reproducible nor accurate. The differences between the PO2 values measured by the electrode and those obtained from intermittent blood samples were within +/- 10 mm Hg during the first 12 hr using the in vivo calibration after electrode stabilization. After 12 hr, the electrode PO2 values using the in vitro cal factor or based upon the in vivo calibration were increased significantly indicating a possible membrane rupture. This occured more rapidly in the animal experiments than in the in vitro studies using a tonometer, suggesting that continuous flow and pressure changes inside of the aorta contribute greatly to mechanical breakage of the membrane. Histologic evaluation indicated the electrode catheter system was thrombogenic at the level of the electrode tip and this thrombogenicity was primarily related to intimal injury caused by the electrode tip movement as a result of flow and pressure changes inside the aorta.     

The San Antonio Biethnic Children's Blood Pressure Study: auscultatory findings.

INTRODUCTION: The purpose of this study were to: (a) examine for possible ethnicity-related and gender-related differences in blood pressure (BP) in Mexican American and non-Hispanic White schoolchildren; (b) compare auscultatory and oscillometric BP levels; and (c) establish auscultatory BP standards using the width of the BP cuff based on the circumference of the arm in schoolchildren in K-12. METHODS: Participants were 6259 schoolchildren in kindergarten through 12th grade in the San Antonio, Texas, area. Auscultatory and oscillometric BP readings were obtained in random sequence, using BP cuff width 40% to 50% of the circumference of the upper arm. Averages of 3 readings were used for statistical analyses. RESULTS: Auscultatory systolic pressures (SPs) in preadolescent Mexican American boys and girls were higher (1 to 3 mm Hg) auscultatory (SP) than in their White counterparts, but the difference was clinically not important. Diastolic pressures (DP) showed no important differences. Auscultatory SPs in 13- to 18-year-old boys of both ethnic groups were significantly (P < .05) higher (3 to 12 mm Hg) than they were for girls, with no ethnic differences. Oscillometric SP was higher than auscultatory SP in children of all ages studied. Oscillometric (DP) was slightly lower (0 to 5 mm Hg) than was auscultatory K4 and higher (4 to 5 mm Hg) than was auscultatory K5 DP. DISCUSSION: No important ethnicity-related difference was found for auscultatory BP, but significant gender-related differences (boys greater than girls) were found in SP in subjects ages 13 to 18 years. Differences in BP readings by oscillometric and auscultatory methods do not allow interchange of readings. This study provides, for the first time, auscultatory BP standards using BP cuff width 40% to 50% of the arm circumference.     

Intratracheal suctioning in sick preterm infants: prevention of intracranial hypertension and cerebral hypoperfusion by muscle paralysis

In a prospective nonrandomized study, using each baby as his or her own control, we compared intracranial pressure (anterior fontanel pressure as measured with the Digilab pneumotonometer), cerebral perfusion pressure, BP, heart rate, transcutaneous Po2, and transcutaneous Pco2 before, during, and after endotracheal suctioning, with and without muscle paralysis, in 28 critically ill preterm infants with respiratory distress syndrome. With suctioning, there was a small but significant increase in intracranial pressure in paralyzed patients (from 13.7 [mean] +/- 4.4 mm Hg [SD] to 15.8 +/- 5.2 mm Hg) but a significantly larger (P less than .001) increase when they were not paralyzed (from 12.5 +/- 3.6 to 28.5 +/- 8.3 mm Hg). Suctioning led to a slight increase in BP with (from 45.3 +/- 9.1 to 48.0 +/- 8.7 mm Hg) and without muscle paralysis (from 45.1 +/- 9.4 to 50.0 +/- 11.7 mm Hg); but there was no significant difference between the two groups. The cerebral perfusion pressure in paralyzed infants did not show any significant change before, during, and after suctioning (31.5 +/- 9.1 mm Hg before v 32.0 +/- 8.7 mm Hg during suctioning), but without muscle paralysis cerebral perfusion pressure decreased (P less than .001) from 32.8 +/- 9.7 to 21.3 +/- 13.1 mm Hg. Suctioning induced a slight decrease in mean heart rate and transcutaneous Po2, but pancuronium did not alter these changes. There was no statistical difference in transcutaneous Pco2 before, during, and after suctioning with and without muscle paralysis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of traditional and plethysmographic methods for measuring pulsus paradoxus

BACKGROUND: In the evaluation of patients with acute asthma, pulsus paradoxus (PP) is an objective and noninvasive indicator of the severity of airway obstruction. However, in children PP may be difficult or impossible to measure. Indwelling arterial catheters facilitate the measurement of PP, but they are invasive and generally reserved for critically ill patients. OBJECTIVE: To determine the utility of the plethysmographic waveform (PPpleth) of the pulse oximeter in measuring PP. METHODS: Patients from the pediatric intensive care unit, emergency department, and inpatient wards of a tertiary care pediatric hospital were eligible for the study. A total of 36 patients (mean age [SD], 11.2 [4.7] years) were enrolled in the study. Pulsus paradoxus was measured using the traditional auscultatory (PPausc) method with a sphygmomanometer. Pulsus paradoxus was then measured using a blood pressure cuff observing for the disappearance and reappearance of the (PPpleth) on the pulse oximeter. Mean difference and 95% confidence intervals were calculated for each method. The 2 methods were also analyzed for correlation and agreement using the Pearson product moment correlation and a Bland and Altman plot. RESULTS: Patients with status asthmaticus had higher PPausc and PPpleth readings compared with nonasthmatic patients. Pulsus paradoxus measured by plethysmography in patients with and without asthma was similar to PPausc readings (mean difference, 0.6 mm Hg; 95% confidence interval, -0.6 to 2.1 mm Hg). Individual PPpleth readings showed significant correlation and agreement with PPausc readings in patients both with and without asthma. CONCLUSION: Measurement of PP using the pulse oximeter-pulse plethysmographic waveform offers a simple and noninvasive method for evaluating patients with airway obstruction.     

Clinical use of continuous arterial blood gas monitoring in the pediatric intensive care unit

CONTEXT: Continuous arterial blood gas monitoring is a new technology based on the combination of opto-chemical and fiber-optic detectors that can measure pH, PCO2, PO2, and temperature on a continuous basis via a sensor placed in an artery. OBJECTIVE: To evaluate this technology in pediatric patients who would normally require frequent arterial blood gas sampling. DESIGN: A criterion standard study in which the results of arterial blood gas samples measured by the laboratory analyzer were compared with the sensor readings. SETTING: A pediatric intensive care unit of a tertiary referral center. PATIENTS: Children with severe respiratory failure who required frequent arterial blood gas sampling and who had a 20-gauge arterial line in either a radial or femoral site. RESULTS: Twenty-four patients with a mean age of 6.4 years (range 1-21 years) had a sensor placed. Sensors were in place for a mean of 101 +/- 62 hours. Eighteen patients underwent continuous monitoring for at least 24 hours or until no longer clinically necessary. There were 414 pairs of blood gas samples obtained. The bias/precision for pH was 0.005/0.030; for PCO2, -1.8/6.3 mm Hg; and for PO2, 1.2/24 mm Hg. The correlation (r value) between the sensor readings and the blood gases were pH 0. 960, PCO2 0.927, PO2 0.813 (P <.01 for all values). The bias and precision for PO2 levels < 70 mm Hg were 0.057/9.34 mm Hg. There were no complications from sensor placement. Continuous blood gas monitoring allowed immediate recognition of clinical changes. CONCLUSION: The continuous arterial blood gas sensor is capable of clinically accurate blood gas measurements. This technology provides the clinician with immediate data that can allow rapid interventions in unstable patients.     

Management of primary congenital glaucoma by trabeculectomy in Nigeria

AIM: To review the management of congenital glaucoma, bearing in mind the limited facilities available in developing countries. METHODS: The medical records of children aged < or = 3 years with primary congenital glaucoma seen at two teaching hospitals and one private eye hospital in Enugu, Nigeria over a 5-year period were reviewed retrospectively. All the children underwent trabeculectomy without use of anti-metabolites. RESULTS: Fifty-seven eyes of 32 patients (5 unilateral, 26 bilateral) were reviewed. Pre-operatively, 63.2% of the eyes had a corneal diameter of 12-15 mm. After surgery, the number with corneal haziness decreased from 25 (43.8%) to 15 (26.4%) (p=0.05). The mean (SD) pre-operative intra-ocular pressure (IOP) was 28.3 (7.5) mmHg and the mean post-operative IOP was 17 (5.6) mmHg (p=0.001). CONCLUSIONS: When facilities for other treatment modalities are not available, primary trabeculectomy without the use of anti-metabolites can be employed to manage primary congenital glaucoma.     

Autoregulation of cerebral blood flow in the preterm fetal lamb

The purpose of the present study was to determine if autoregulation of cerebral blood flow (CBF) is present in the preterm fetal lamb and, if present, to measure the range of mean arterial blood pressure over which autoregulation exists. Thirty-seven measurements of CBF were made in seven preterm fetal lambs (118-122 days gestation) over a mean carotid arterial blood pressure (CBP) range of 18-90 mm Hg. CBF was measured by the radionuclide-labeled microsphere technique. CBP was altered by graduated inflation of balloons placed around the brachiocephalic trunk and the aortic isthmus. To eliminate the effects of reflex changes in heart rate, the carotid sinus and aortic nerve were ablated bilaterally. CBF was linearly related to mean CBP from 18-45 mm Hg, constant over a mean CBP of 45-80 mm Hg, and again linear from 80-90 mm Hg. Resting mean CBP (normotension) was 53.8 +/- 1.9 mm Hg during the control period and 51.7 +/- 0.8 mm Hg during the equilibration periods. This study demonstrates that although autoregulation of CBF is intact in the preterm fetal lamb, the range is narrowed compared to the term lamb and resting mean CBP lies close to the lower limit of autoregulation.     

Long-term results of trabeculectomy with different concentrations of mitomycin C in refractory developmental glaucoma

PURPOSE: To evaluate the long-term results of trabeculectomy with two different concentrations of mitomycin C in refractory developmental glaucoma. PATIENTS AND METHODS: A total of 48 eyes of 37 patients with previous failure of congenital glaucoma surgery underwent mitomycin C-augmented trabeculectomy. Data were analyzed retrospectively, and patients were divided into two groups. Group 1 consisted of 18 patients (25 eyes) who underwent trabeculectomy with a 0.4 mg/mL mitomycin C solution and group 2 consisted of 19 patients (23 eyes) who underwent trabeculectomy with a 0.2 mg/mL mitomycin C solution. Pre- and postoperative intraocular pressure (IOP), best-corrected visual acuity, bleb characteristics, success rate, and complications were compared for both groups. RESULTS: Mean time between primary surgery and mitomycin C-augmented trabeculectomy was 19.3 months (range, 11 months to 7 years). Mean preoperative IOP was 28.4 +/- 2.9 mm Hg in group 1 and 29.0 +/- 2.4 mm Hg in group 2. Final postoperative IOP was 17.0 +/- 1.6 for group 1 and 17.1 +/- 1.4 mm Hg for group 2. There were no significant differences between the groups for IOP, success rate, and complications (P > .05). The most common postoperative complication was shallow anterior chamber (11 [22.9%] of 48 eyes). CONCLUSIONS: A 0.4 or 0.2 mg/mL mitomycin C solution for 4 minutes may be used during trabeculectomy in refractory developmental glaucoma.     

Effect of environmental hypothermia on vitelline artery blood pressure and vascular resistance in the stage 18, 21, and 24 chick embryo

We studied the effect of environmental hypothermia on arterial blood pressure, dorsal aortic blood flow, and vascular resistance in stage 18, 21, and 24 chick embryos. The arterial pressure was measured with a servonull micropressure system. Mean dorsal aortic blood flow was calculated from pulsed-Doppler measurement of mean dorsal aortic blood velocity and dorsal aortic diameter. Vascular resistance was calculated by dividing mean vitelline arterial blood pressure by dorsal aortic blood flow. Sequential data were obtained at temperatures of 34.7, 31.1, and 34.1 degrees C. At stage 21, the vitelline arterial blood pressure decreased from 0.82 +/- 0.03 (means +/- SEM) to 0.72 +/- 0.03 mm Hg on cooling and increased from 0.66 +/- 0.05 to 0.87 +/- 0.06 mm Hg on rewarming (p less than 0.05). At stage 21, mean dorsal aortic blood flow decreased from 0.49 +/- 0.02 to 0.33 +/- 0.02 mm3/s with cooling and increased from 0.34 +/- 0.02 to 0.47 +/- 0.02 mm3/s with rewarming. The vascular resistance in stage 21 embryos increased after cooling from 1.68 +/- 0.19 to 2.23 +/- 0.39 mm Hg/mm3/s (means +/- 95% confidence interval). The changes were similar in stage 18 and 24 embryos. We conclude that the reduction of vitelline artery blood pressure resulted from a decrease in cardiac output. In addition, we noted that the vitelline arterial vascular bed can constrict in response to hypothermia prior to autonomic innervation. These changes in hemodynamics may be a teratogenic mechanism for hypothermia-induced cardiac defects in the chick embryo.