Non-Newtonian Topological Mechanical Metamaterials Using Feedback Control.

We introduce a method to design topological mechanical metamaterials that are not constrained by Newtonian dynamics. The unit cells in a mechanical lattice are subjected to active feedback forces that are processed through autonomous controllers preprogrammed to generate the desired local response in real time. As an example, we focus on the quantum Haldane model, which is a two-band system with nonreciprocal coupling terms, the implementation of which in mechanical systems requires violating Newton's third law. We demonstrate that the required topological phase characterized by chiral edge modes can be achieved in an analogous mechanical system only with closed-loop control. We then show that our approach enables us to realize, a modified version of the Haldane model in a mechanical metamaterial. Here, the complex-valued couplings are polarized in a way that modes on opposite edges of a lattice propagate in the same direction, and are balanced by counterpropagating bulk modes. The proposed method is general and flexible, and could be used to realize arbitrary lattice parameters, such as nonlocal or nonlinear couplings, time-dependent potentials, non-Hermitian dynamics, and more, on a single platform.

[BLUE BABY, PINK FUTURE].

Neonatal cyanosis is relatively common. It is usually a consequence of cyanotic heart disease or a pulmonary disorder, and warrants a thorough and quick investigation. Mutations causing decreased affinity of hemoglobin to oxygen may change α1 to ß2 binding. We describe a new mutation (asp 102 serine), in the γ chain of hemoglobin, causing neonatal cyanosis which resolves as the baby matures. In this case we would like to emphasize the importance of early diagnosis in order to avoid unnecessary disease workup.

Perinatal risk factors for bronchopulmonary dysplasia in a national cohort of very-low-birthweight infants.

OBJECTIVE: We sought to assess the independent effect of perinatal factors on the risk for bronchopulmonary dysplasia (BPD) in very-low-birthweight infants. STUDY DESIGN: This was a population-based observational study. Data were prospectively collected by the Israel Neonatal Network. Multivariable analyses identified independent risk factors for BPD. RESULTS: Of 12,139 infants surviving to a postmenstrual age of 36 weeks, 1663 (13.7%) developed BPD. BPD was independently associated with young maternal age (odds ratio [OR], 1.53), maternal hypertensive disorders (OR, 1.28), antepartum hemorrhage (OR, 1.26), male gender (OR, 1.41), non-Jewish ethnicity (OR, 1.23), birth defects (OR, 1.94), small for gestational age (GA) (OR, 2.65), and delivery room resuscitation (OR, 1.86). Stratified analysis by GA groups showed that postdelivery resuscitation had a more pronounced effect with increasing maturity. CONCLUSION: Perinatal factors and pregnancy complications were independently associated with development of BPD in very-low-birthweight infants. Most risk factors identified were consistent within GA groups.

Targeted fluconazole prophylaxis for high-risk very low birth weight infants.

Antifungal prophylaxis is increasingly used in very low birth weight (VLBW) infants who are at risk for severe fungal infections. Our objective was to assess the effectiveness of targeted fluconazole prophylaxis for high-risk VLBW infants. A retrospective cohort study with historical controls was performed. During the period 2007-2008, all high-risk VLBW infants (birth weight, ≤1,000 g; gestational age, ≤28 weeks; seven antimicrobial therapy or additional risk factors present) received fluconazole prophylaxis until risk factors were not present. Treated infants were compared to a gestational age- and birth weight-matched untreated cohort. Statistical analyses used univariate and multivariate analyses. The main outcome variable was a breakthrough fungal bloodstream infection (BSI). The prophylaxis cohort of 130 VLBW infants was compared to 319 control infants. The rate of fungal infections was significantly lower in the fluconazole prophylaxis group (1 of 130 vs. 19 of 319, p = 0.016); however, they did not differ in mortality (16.2 vs. 15 %, p = 0.77) or complications of prematurity. Fluconazole prophylaxis was associated with a significant decrease in candidal BSI (odds ratio, 0.05; 95 % confidence interval, 0.005-0.523). Selective vs. nonselective prophylaxis reduced the number of infants treated from 247 to 130. Conclusion Targeted fluconazole prophylaxis in VLBW infants is effective in preventing fungal infections without increasing the risk of BSI among low-risk infants.

New syndrome of congenital circumferential skin folds associated with multiple congenital anomalies.

Congenital circumferential skin folds can be found in individuals with no additional defects, as well as in patients with multiple congenital anomalies and developmental abnormalities. Current data point to etiological heterogeneity of syndromic cases. We describe a 7-month-old girl with a novel combination of symmetrical congenital circumferential skin folds, dysmorphic features, and multiple congenital abnormalities. Examination of the patient revealed symmetrical congenital circumferential skin folds and dysmorphic features, as well as multiple congenital anomalies including nasal pyriform aperture stenosis, ventricular septal defect, absent spleen, camptodactyly, and severe psychomotor retardation. Skin biopsy demonstrated subcutaneous fat extending into the superficial and deep reticular dermis. Sequencing of the CDON, SHH, ZIC2, SIX3, and TGIF genes (associated with holoprosencephaly) did not disclose pathogenic alterations. Extensive review of previously described cases of syndromic congenital circumferential skin folds did not reveal a similar combination of clinical and histopathological findings.

Intravitreal bevacizumab as supplemental treatment or monotherapy for severe retinopathy of prematurity.

PURPOSE: To investigate the benefit of intravitreal bevacizumab as supplemental or primary treatment for retinopathy of prematurity. METHODS: The files of nine consecutive infants treated with intravitreal bevacizumab for bilateral severe posterior retinopathy of prematurity were reviewed. RESULTS: Gestational age was 24 weeks to 27 weeks, and birth weight was 660 g to 1,131 g. Indications for treatment were retinopathy of prematurity progression from Stage 3 to 4A or 2 to 3 with extraretinal neovascularization despite laser treatment; active neovascular Stage 4A disease after laser and cryo-treatment; anterior segment neovascularization and bleeding after laser treatment; and aggressive posterior disease with tunica vasculosa lentis and vitreous haze, which prevented laser treatment. One patient (two eyes) underwent lens-sparing vitrectomy after bevacizumab treatment; one eye acquired macular fold. One patient underwent bilateral scleral buckle. Bevacizumab treatment was associated with subsidence of the active vascular component in all eyes. Anatomical results were favorable in 17 eyes. There were no local or systemic complications. CONCLUSION: Intravitreal bevacizumab may serve as a supplemental therapeutic agent for severe laser-refractory retinopathy of prematurity or as monotherapy when media opacities preclude diode laser photocoagulation or the patient is too sick for lengthy laser treatment.

Association of high-dose bifonazole administration during early pregnancy and severe limb reduction defects in the newborn.

BACKGROUND: Neonatal limb reduction defects may be caused by exposure to an external agent. The azole derivatives are used in the treatment of systemic and dermal mycoses. Their relative teratogenic risk is still controversial. CASES: We describe two newborns with severe limb defects who were exposed to high doses of oral (an unacceptable route) and/or intravaginal bifonazole during the entire first trimester of pregnancy. CONCLUSION: Although only two cases are insufficient to establish a relationship, our data suggest that maternal intake of bifonazole in early pregnancy poses a risk of morphogenic malformations. The literature suggests several possible mechanisms.

Treatment of patent ductus arteriosus: indomethacin or ibuprofen?

We compared ibuprofen and indomethacin for the treatment of patent ductus arteriosus (PDA) in preterm infants. A retrospective comparative study was conducted at a pediatric tertiary center in preterm infants diagnosed with PDA. Infants born from January 2000 to June 2003 were treated with indomethacin, whereas infants born from July 2003 to November 2005 were treated with ibuprofen. The two treatment groups were compared. Demographic data and clinical, laboratory, and outcome data were collected from the medical files. Seventy-three infants were included in the ibuprofen group and 46 in the indomethacin group. No significant difference in efficacy was found between indomethacin and ibuprofen. Compared with ibuprofen, indomethacin treatment was associated with significantly higher mean creatinine levels and a higher percent of infants with creatinine >1.2 mg/dL, hyponatremia <120 mmol/L, and platelet level <100,000 platelets/mL(3). There were no significant differences in bilirubin levels, incidence and grade of intraventricular hemorrhage, necrotizing enterocolitis, retinopathy of prematurity, rate of surgical duct ligation, sepsis, length of hospital stay, or mortality. Indomethacin and ibuprofen are equally effective for PDA closure in premature infants. Treatment with ibuprofen is safer, decreasing the risk of renal failure, thrombocytopenia, and hyponatremia.

Epidemiology and risk factors for early onset sepsis among very-low-birthweight infants.

OBJECTIVE: The purpose of this study was to determine the incidence, causative pathogens, and risk factors for early onset sepsis (EOS) among very-low-birthweight (VLBW) infants. STUDY DESIGN: This was a population based observational study. Data were prospectively collected by the Israel Neonatal Network between 1995 and 2005. Multivariable analyses identified independent risk factors for EOS. RESULTS: EOS developed in 383 of 15,839 infants (2.42%). Fifty-five percent of pathogens isolated were gram-negative bacteria. Lack of prenatal care (odds ratio [OR], 1.94; 95% confidence interval [CI], 1.32-2.86), delivery room resuscitation (OR, 2.49; 95% CI, 1.91-3.24), membrane rupture > 24 hours without amnionitis (OR, 2.10; 95% CI, 1.53-2.88), amnionitis with membrane rupture < 24 hours (OR, 4.28; 95% CI, 2.97-6.16), and amnionitis with membrane rupture >or= 24 hours (OR, 8.15; 95% CI, 5.98-11.10) were associated with EOS, but not antenatal steroids or gestational age. CONCLUSION: EOS was caused mainly by gram-negative bacteria. Prolonged rupture of membranes and amnionitis have an additive effect on EOS with an above 8-fold excess risk when both were present.

Are selective serotonin reuptake inhibitors cardiac teratogens? Echocardiographic screening of newborns with persistent heart murmur.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have been suspected of cardiac teratogenicity, but reports have been inconsistent. Our aim was to investigate the rate of nonsyndromic congenital heart defects in newborns exposed in utero to SSRIs compared with unexposed controls. METHODS: This prospective study of women who gave birth at our tertiary center from 2000 to 2007 yielded 235 women who reported first-trimester SSRI use during pregnancy. All newborns born during the study period and found to have a persistent cardiac murmur on day 2 or 3 of life were referred for examination by a pediatric cardiologist and by echocardiography. The findings were compared between the newborns who were exposed to SSRIs and those who were not. RESULTS: Nonsyndromic congenital heart defects were identified by echocardiography in 8 of 235 (3.40%) newborns exposed in utero to SSRIs and in 1083 of 67,636 (1.60%) non-exposed newborns. The difference in prevalence between the two groups was significant (relative risk, 2.17; 95% confidence interval, 1.07-4.39). The prevalence rates for paroxetine and fluoxetine exposure were 4.3% and 3.0%, respectively. All cardiac defects in the study group were mild: ventricular septal defect (6), bicuspid aortic valve (1) and right superior vena cava to coronary sinus (1). CONCLUSIONS: Newborns exposed in utero to SSRIs, have a twofold higher risk of mild nonsyndromic heart defects than unexposed infants. The data suggest that women who require SSRI treatment during pregnancy can be reassured that the fetal risk is low and possible cardiac malformations will probably be mild. Late-targeted ultrasound and fetal echocardiography at 22 to 23 weeks' gestation are recommended in this patient group.

Risk factors for pneumothorax in very low birth weight infants.

OBJECTIVES: To identify risk factors for pneumothorax in very low birth weight infants. DESIGN: Retrospective case-control study. SETTING: Neonatal intensive care unit in a pediatric tertiary care center. PATIENTS: Very low birth weight infants. INTERVENTIONS: All very low birth weight infants with pneumothorax born during the period January 1997 through December 2002 were identified. These infants were matched to infants without pneumothorax for gestational age, birth weight, and gender. Perinatal, neonatal, and treatment variables were collected for all infants. MEASUREMENTS AND MAIN RESULTS: Very low birth weight infants with pneumothorax were compared with those without. Univariate analysis was performed using the paired Student's t-test for continuous variables and the McNemar test for categorical variables. All variables were entered into a stepwise logistic regression model using a paired case-control design. Statistical significance was defined at p < .05. Seventy-four of 679 very low birth weight infants (10.9%) admitted to the neonatal intensive care unit developed a pneumothorax and were matched to 74 control infants. Multivariate analysis showed that only factors present on the day of pneumothorax were associated with pneumothorax. An increased risk of pneumothorax was associated with maximal, peak inspiratory pressure (odds ratio [OR] 1.33, 95% confidence interval [CI] 1.07, 1.66), minimal Fio2 (OR 2.18, 95% CI 1.14, 4.17), pulmonary hemorrhage (OR 27.5, 95% CI 2.3, 337), and maximal arterial CO2 (OR 1.94, 95% CI 1.13, 3.34), while a decreased risk was associated with maximal positive end-expiratory pressure (OR 0.71, 95% CI 0.56, 0.91). CONCLUSIONS: Pneumothorax is associated with factors present on day of pneumothorax and not with initial ventilation variables or initial severity of lung disease. Decreasing the risk of pneumothorax requires rigorous control of ventilation, including optimizing positive end-expiratory pressure and minimizing peak inspiratory pressure.

New and improved Israeli reference of birth weight, birth length, and head circumference by gestational age: a hospital-based study.

BACKGROUND: Many centers in Israel still use pre-1970 reference data for neonatal weight, length and head circumference. A recently published population-based reference overestimated the weight of premature infants. OBJECTIVE: To develop a national reference for birth weight, birth length and head circumference by gestational age for singleton infants in Israel. METHODS: Data were collected on all singleton live births documented in the neonatal registry of Rabin Medical Center from 1991 to 2005 (n=82,066). Gestational age estimation was based on the last menstrual period until 1977 and early fetal ultrasound thereafter. Neonates with an implausible birth weight for gestational age (identified by the rule of median +/- 5 standard deviations or expert clinical opinion) were excluded. Reference tables for fetal growth by gestational age were created for males and females separately. RESULTS: The growth references developed differed markedly from the Usher curves currently used in our department. Compared to the recently published population-based birth weight reference, our data were free of the problem of differential misclassification of birth weight for gestational age for the premature infants and very similar for the other gestational age groups. This finding reinforced the validity of our measurements of birth weight, as well as of birth length and head circumference. CONCLUSIONS: Use of our new (birth length and head circumference) and improved (birth weight) gender-specific hospital-based reference for fetal growth may help to define normal and abnormal growth in the neonatal population of Israel and thereby improve neonatal care and public health comparisons.

The existence of gender difference in IL-1Ra gene polymorphism.

Interleukin-1beta (IL-1beta) and its endogenous antagonist IL-1 receptor antagonist (IL-1ra) play an important role in various inflammatory responses. The production of IL-1 and IL-1ra is regulated by genotypic and nongenotypic factors and is different between men and women. The aim of this study was to examine the existence of gender difference in the genetic polymorphism of these two cytokines. The genotypes of IL-1beta-511 biallelic polymorphism and that of IL-1Ra (IL-1RN) penta-allelic polymorphism were determined in 319 healthy Jewish subjects, 156 female and 163 male, using PCR amplification. The results showed that there was a gender difference in IL-1Ra gene polymorphism expressed by a higher incidence of IL1RN*1/IL1RN*1 homozygotes and a lower occurrence of IL1RN*1/IL1RN*2 heterozygotes in men compared with women. Furthermore, allele IL1RN*1 was more frequent in men, whereas allele IL1RN*2 was more prevalent in women. There was no difference in IL-1beta gene polymorphism between the two genders. It is conceivable that the gender difference in IL-1Ra gene polymorphism found in the current study may affect IL-1 and IL-1ra levels. This diversity might be one of the causes for the sex differences in immune response observed in various conditions, such as autoimmune diseases, pain perception, and premature delivery.

Retinopathy of prematurity in assisted versus natural conception and singleton versus multiple births.

OBJECTIVES: To determine whether the incidence and severity of retinopathy of prematurity (ROP) differs between infants conceived naturally and those born after assisted conception, and to analyze the impact of singleton versus multiple gestation on ROP. DESIGN: Comparative case series. PARTICIPANTS: The study group consisted of 363 infants with a birth weight (BW) of < or =1500 g who were hospitalized in the neonatal unit of a single tertiary-care center between 1998 and 2000. METHODS: Data on gestational age (GA), BW, type of pregnancy (singleton/multiple), and type of conception (natural/assisted) were recorded, in addition to the ophthalmological results. Ophthalmological examinations were performed routinely at 4 weeks and repeated later, depending on the severity of the findings. MAIN OUTCOME MEASURES: Presence and stage of ROP were compared between infants conceived naturally and those conceived by assisted technology, and between singleton and multiple-birth infants. RESULTS: Mean GA at birth was 29.4 weeks (standard deviation, 2.5; range, 23-36). Two hundred four neonates (56.2%) were conceived naturally and 159 were conceived by assisted conception, either in vitro fertilization (IVF) alone (n = 119 [32.85%]) or IVF combined with drug treatment (n = 40 [11%]). Sixty-four infants in the natural conception group were the product of multiple pregnancies, as were 103 infants in the assisted conception group. Retinopathy of prematurity was noted in 159 of 363 infants (43.8%): 89 conceived naturally (71% singletons, 28% twins, and 17% triplets) and 70 born by assisted conception (70% singletons, 47% twins, and 33% triplets). There was no significant difference in either occurrence or severity of ROP between the natural conception and assisted conception groups. Singletons had a significantly higher rate of advanced ROP (stages II-III) (30.2%) than twins (23.1%), triplets, and quadruplets (10.6%) (P = 0.024). On multiple regression analysis, low GA and BW were the variables most significantly associated with ROP. CONCLUSIONS: In our sample, assisted conception per se did not appear to be a risk factor for ROP. Singleton babies with a birth weight of < or =1500 g were more prone to develop ROP stages II and III than twins or triplets. Gestational age and BW were the most significant factors associated with ROP.

Monthly number of preterm births and environmental physical activity.

UNLABELLED: Recent studies have reported links between external physical factors and human homeostasis. OBJECTIVE: to determine whether the monthly values of specific physical environmental factors are associated with the monthly number of preterm births in a major medical center in Israel. METHODS: The sample included 1006 infants weighing less than 1500g born live to 774 mothers during 96 consecutive months (1995-2002) at a tertiary medical center in Israel. Monthly values of indices of solar, cosmic ray, and geomagnetic activity for the same period were obtained from national data monitoring facilities in the United States of America, Russia, and Finland. The findings were statistically correlated with the monthly number of preterm births. RESULTS: The number of preterm births correlated with the month of the year (1-12), with a progressive rise in the number of infants born as the year progressed (p = .02). The monthly number of preterm births showed a significant and direct correlation with solar activity indices (r = .32, p = .0016), and a significant and inverse correlation with cosmic ray activity indices (r = -0.3, p = .008). The relation was significant only for singelton births and for the whole group of preterm newborns, but not for multiple pregnancies. CONCLUSION: Our findings suggest that solar and cosmic ray activity may play a role in the timing of premature labor, however in multiple pregnancies additional factors are dominant.

Neonatal abstinence syndrome after in utero exposure to selective serotonin reuptake inhibitors in term infants.

OBJECTIVE: To compare the prevalence and clinical characteristics of neonatal abstinence syndrome in neonates exposed and not exposed to selective serotonin reuptake inhibitors (SSRIs) in utero. DESIGN: Cohort study. SETTING: Tertiary care center. Patients One hundred twenty term infants, of whom 60 had prolonged in utero exposure to SSRIs, including paroxetine hydrochloride, fluoxetine, citalopram hydrobromide, sertraline hydrochloride, and venlafaxine hydrochloride. MAIN OUTCOME MEASURES: Neonatal abstinence syndrome was assessed with the Finnegan score as follows: score of 8 or above, severe; score of 4 to 7, mild; and score of 0 to 3, normal. All infants were followed up with a standardized protocol that included repeated Finnegan score assessments and cardiorespiratory monitoring until normalization of the Finnegan score. RESULTS: Of the 60 neonates exposed to SSRIs in utero, 8 showed severe and 10 showed mild symptoms of a neonatal abstinence syndrome. All nonexposed neonates had a normal Finnegan score. In neonates who developed severe symptoms, the maximum mean daily Finnegan scores were recorded within 2 days after birth, although maximum individual scores were recorded as long as 4 days after birth. CONCLUSIONS: Neonatal abstinence syndrome occurs in 30% of neonates exposed to SSRIs in utero. These neonates should be monitored for at least 48 hours after birth. The long-term effects of prolonged exposure to SSRIs, particularly in neonates who develop severe symptoms, have yet to be determined.

Short- and Long-term Pulmonary Outcome of Palivizumab in Children Born Extremely Prematurely.

BACKGROUND: Palivizumab reduces the severity of respiratory syncytial virus infection in premature infants, but whether there is a protective effect beyond the preschool age is unknown. This study sought to assess the short- and long-term effects of palivizumab immunization on respiratory morbidity and pulmonary function at school age in children born extremely prematurely. METHODS: Infants born before 29 weeks' gestation in 2000 to 2003 were assessed at school age by parental questionnaire, hospital chart review, and lung function tests. Children born immediately before the introduction of routine palivizumab prophylaxis were compared with age-matched children who received palivizumab prophylaxis during the first respiratory syncytial virus season. RESULTS: Sixty-three children with a mean age 8.9 years were included: 30 had received palivizumab and 33 had not (control subjects). The groups were similar in terms of gestational age, birth weight, need for mechanical ventilation, and oxygen supplementation. Fifty-three percent of the palivizumab group, compared with 39% of the control group, had bronchopulmonary dysplasia (P = .14). Wheezing occurred in the first 2 years of life in 27% of the palivizumab group and in 70% of control subjects (P = .008); respective hospitalization rates were 33% and 70% (P = .001). At school age, rates of hyperresponsiveness (provocative concentration leading to a 20% fall in FEV1 < 1 mg/mL) were 33% and 48%, respectively (P = .38). Spirometry, lung volumes, diffusion, and exhaled nitric oxide were within normal limits, with no significant differences between groups. CONCLUSION: Palivizumab prophylaxis was associated with reduced wheezing episodes and hospitalizations during the first 2 years of life in children born extremely prematurely. However, it did not affect pulmonary outcome at school age.

Ocular growth in premature infants conceived by in vitro fertilization versus natural conception.

PURPOSE: To evaluate the possible effect of in vitro fertilization (IVF) on early development of the eye in premature infants. METHODS: Biometric and keratometric values, intraocular pressure, and retinal vascular status were assessed in a cohort of 133 premature infants. These values were compared between premature infants conceived by IVF or naturally, and the relationship between these parameters and postconceptional age and weight at examination were evaluated. RESULTS: The sample consisted of 133 premature infants, 62 (46.6%) born by IVF and 71 (53.4%) by natural conception. Postconceptional age at examination was 28 to 46 weeks. In both groups, axial length, anterior chamber depth, and corneal radius correlated with the postconceptional age and weight at examination and followed a linear growth pattern. Lens thickness changed very slightly. The rate of retinal vascularization correlated with the postconceptional age as well. No correlation was found between intraocular pressure and corrected age or weight at examination. There was no difference between the study and control groups in any of the biometric or keratometric parameters or in intraocular pressure, according to two-way analysis of variance. CONCLUSIONS: IVF apparently does not affect early ocular growth, intraocular pressure, changes in corneal curvature, or retinal vascularization in premature infants. These findings may aid ophthalmologists in assessing ocular dimensions in this patient population.

Ultrasonographic demonstration of the superior ophthalmic vein in the orbit of premature infants with and without retinopathy of prematurity.

Retinopathy of prematurity (ROP), which develops due to abnormal retinal vascularization in premature babies, can lead to irreversible vision loss. B-scan ocular ultrasonography is a noninvasive examination which makes it possible to image the eye and orbit. Our purpose was to echographically assess the orbit of premature babies with and without retinopathy of prematurity (ROP), with a focus on the superior ophthalmic vein (SOV) which is normally not detected by orbital ultrasound. A prospective study design was used after approved by the local institutional review board. ROP was diagnosed by routine ophthalmoscopic exam. Orbital ultrasound was performed by a single experienced ophthalmologist and ultra-sonographer who was masked to the routine ROP screening results. The results of the ophthalmoscopic exam were compared to the orbital ultrasound findings. The study group was divided into those diagnosed with ROP and those not diagnosed with ROP and were found to be comparable by age and weight at the time of the US examination. The SOV was dilated in 21 of 22 eyes (95.4%) with ROP and in only 5 of 32 eyes (15.6%) without ROP. The present study suggests an association between ROP and dilatation of the SOV.

Intraocular pressure variations after diode laser photocoagulation for threshold retinopathy of prematurity.

PURPOSE: To investigate the intraocular pressure (IOP) variations occurring after indirect diode laser photocoagulation for threshold retinopathy of prematurity. DESIGN: Prospective, nonrandomized, comparative study. PARTICIPANTS: A study group-21 consecutive premature babies (42 eyes) undergoing diode laser photocoagulation for retinopathy of prematurity-and control groups-32 premature babies (64 eyes) undergoing retinal examination with or without scleral indentation. INTERVENTION: Intraocular pressure was measured with a portable electronic tonometer before, immediately after, and 1, 2, and 3 days after diode laser photocoagulation in the study group; before retinal examination in control group 1; and before and after retinal examination with scleral indentation in control group 2. MAIN OUTCOME MEASURE: Intraocular pressure after diode laser photocoagulation for threshold retinopathy of prematurity. RESULTS: Mean IOP in the study group rose from 15 mmHg (standard deviation [SD] = 4.1) before coagulation to 33.2 mmHg (SD = 7.8; range, 20-50) immediately after, and then dropped to 22.2 (SD = 5.2), 16.5 (SD = 3), and 14.5 mmHg (SD = 2.1) 1, 2, and 3 days later, respectively. All the changes were statistically significant at P<0.0001, except for the difference between days 2 and 3 (P = 0.096). Mean baseline IOPs were 16.3 mmHg (SD = 3.7) in control group 1 and 15.7 mmHg (SD = 2.3) in control group 2 (P = 0.84 between control group 1 and study group, and P = 0.32 between control group 2 and the study group). At termination of the retinal examination with scleral indentation (control group 2), IOP measured 15.1 mmHg (SD = 2.2) (P = 0.49 compared with baseline). CONCLUSIONS: Intraocular pressure may be significantly elevated after diode laser photocoagulation for retinopathy of prematurity. The mechanism and long-term clinical implications of this observation should be investigated.