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PubMed1989

[Examination strategies in the preparative phase for cataract operations and artificial lens implantation].

The extraordinary increase in the number of posterior chamber intraocular lenses (IOLs) implanted in recent years has completely changed our attitude towards cataract patients. A few years ago, the goal of preoperative evaluation was to select ideal candidates for implantation. In the meantime, contraindications to IOLs have become very rare and many tests have been developed to objectify and quantify lens opacities in patients with good visual acuity (glare disability tests, contrast sensitivity tests), or to predict the functional clinical result (macular function tests). The value of these tests is reduced by the rate of false-positive or false-negative results. A meticulously recorded history and careful enlightenment of the patient are indispensable to avoid postoperative disappointment. Slit-lamp observation and biometry are the only mandatory tests for establishing the presence of a cataract and planning the surgical approach. All modern tests attempt to substitute automatic or semi-automatic measurements for clinical judgment, but indication for cataract surgery nevertheless remains a clinical act.

Humans↗

PubMed1989

[Flattening of the anterior chamber and myopic results in sulcus fixation of posterior chamber lenses].

Ultrasonographic biometry was performed in 56 patients immediately after implantation of a posterior chamber intraocular lens to measure the position of the lens. A modified applanation method was used to avoid injury to the scleral suture. Ten months later, 44 of these patients were examined by the same method. The anterior chamber depth was found to have decreased from 4.26 mm (s = 0.39 mm) in the immediate postoperative period to 4.2 mm ten months later. However, axial length, at 23.28 mm postoperatively and 23.34 mm at follow-up, and mean corneal refraction (43.28 D and 43.34 D, respectively) were practically unchanged. There was a shift in the spheric equivalent of refraction from postoperative emmetropia (mean -0.07 D) to slight myopia (mean -0.76 D) at follow-up. This mean myopization of 0.69 D corresponded to the tendency toward a shallower anterior chamber. Shrinkage and fibrosis of the posterior capsule, reduced elasticity of the polypropylene loops, flattening of the cornea and axial changes are discussed as possible causes. The tendency toward myopization should be taken into account when calculating the power of sulcus-fixated posterior chamber lenses.

Anterior Chamber↗

PubMed1985

[A simplified ultrasonographic measuring technic in combination with a computer program for calculating the power of intraocular lenses].

In the last few years intraocular lens implantations have gained in popularity. In biometry new electronic methods have been introduced. For measuring the axial length by ultrasound we use the Ocuscan DBR 400 ST unit in combination with the digital storage system and an immersion technique. For lens power calculation we have developed a new computer program for a Commodore CBM 4032 using R.D. Binkhorst's formulae. In a series of 50 Kelman S-Flex anterior chamber lenses we found a mean error of +0.250 D and a standard deviation of +/- 0.662 D. Sixty-four percent of predictions were within the +/- 0.5 D range, and in 88% of these patients we predicted within the +/- 1.0 D range. The maximum errors of prediction were -1.0 D and +/- 1.75 D. Using an immersion technique an accurate axial length measurement can be obtained.

Computers↗

PubMed1982

[Quality assurance for diagnostic ultrasonic equipment in A- and B-mode in ophthalmology (author's transl)].

Quality assurance for diagnostic ultrasound in ophthalmology is of growing importance and will be the subject of new standards and regulations. Methods for equipment performance testing by means of electric test signals in A- and B-mode equipment are described, both for comparative evaluation of equipment and for routine quality assurance tests. Newly developed test signal generator for checking the time scale in ultrasonic biometry of the eye are presented.

Eye Diseases↗

PubMed2002

The comprehensive midtrimester test: high-sensitivity Down syndrome test.

OBJECTIVE: The purpose of this study was to develop a highly sensitive algorithm for midtrimester Down syndrome detection. STUDY DESIGN: Urine (hyperglycosylated human chorionic gonadotropin, beta-core fragment of human chorionic gonadotropin), serum (alpha-fetoprotein, human chorionic gonadotropin and unconjugated estriol [uE(3)]), and ultrasound biometry (nuchal thickness, humerus length, the presence of gross ultrasonographic anomalies), and maternal age were measured at genetic amniocentesis. Stepwise logistic regression analysis was used to identify the most significant markers. A multivariate Gaussian algorithm plus age was used to derive patient-specific Down syndrome risk. Sensitivity and false-positive rates at different risk thresholds and the area under the receiver-operating characteristic curve were determined. A probability value of <.05 was significant. RESULTS: There were 568 study cases with 17 Down syndrome cases (3.0%). The mean (+/-SD) maternal and gestational ages for the study group were 36.9 (+/-3.5) years and 16.2 (+/-1.4) weeks, respectively. The significant markers were nuchal thickness (P =.0001), hyperglycosylated human chorionic gonadotropin(P <.001), and beta-core fragment (P <.002). Neither maternal age nor gross sonographic anomaly contributed significantly to Down syndrome detection. The comprehensive midtrimester test was extremely efficient for Down syndrome detection in advanced maternal age only cases with a sensitivity of 92.3% at a 0.8% false-positive rate. In women <35 years old, all the Down syndrome cases were detected at 2.2% false positive rate. For the overall population, the sensitivity was 93.7% at 5% false-positive rate. CONCLUSION: In a preliminary study, the comprehensive midtrimester test appeared highly sensitive in different age groups. Gross anomaly detection was not required for high performance, which makes the comprehensive midtrimester test potentially suitable for low-risk screening and as an alternative to amniocentesis in women who wish to avoid the procedure. This was a small study; thus, the clinical value of this test can only be established in large trials.

Adult↗

PubMed2000

Optic nerve hypoplasia and small eyes in presumed amblyopia.

PURPOSE: To assess the anatomy of eyes presumed to be amblyopic and their fellow eyes. PARTICIPANTS: Two hundred seventy-five patients diagnosed with amblyopia and 88 healthy or glaucomatous subjects. METHODS: All subjects underwent complete examinations, including cycloplegic refraction, slit lamp examination, ophthalmoscopy, and retinal imaging. Axial lengths were determined on 263 amblyopic and 88 healthy and glaucomatous subjects by ultrasonic biometry. MAIN OUTCOME MEASURES: Optic disc areas were determined by magnification correction of disc images performed with formulas. Dysversion of the optic disc was determined by simultaneous viewing of disc photographs, digitized images of both eyes, or both. RESULTS: The mean disc area of eyes presumed to be amblyopic was 1.72 mm(2) +/- 0. 73 SD and 1.95 mm(2) +/- 0.69 SD for nonamblyopic eyes (P =.0017). The mean disc area for 176 optic discs of glaucomatous and healthy eyes was 2.61 mm(2) +/- 0.95 SD. The mean axial length for eyes in the general population is 23.65 mm +/- 1.35 SD. The healthy and glaucomatous group in this study had a mean axial length of 23.89 mm +/- 1.29 SD. The eyes with poorer vision that were assumed to be amblyopic averaged 22.42 mm +/- 2.01 SD in length, whereas their nonamblyopic fellow eyes averaged 22.83 mm +/- 1.89 SD (P =.022). The differences between eyes in the healthy population and eyes that are presumably amblyopic, as well as the healthy and fellow eyes, are highly significant (P <.0001)(7.0 x 10(-16)). CONCLUSION: Vision impairment in presumed amblyopia is associated with optic nerve hypoplasia with relative microphthalmos, which is more notable in those eyes with poorer vision.

Adolescent↗

PubMed2002

The effect of corneal thickness and corneal curvature on pneumatonometer measurements.

PURPOSE: The purpose of this study was to investigate the influence of corneal topography and thickness on intraocular pressure (IOP) and pulse amplitude (PA) as measured using the Ocular Blood Flow Analyzer (OBFA) pneumatonometer (Paradigm Medical Industries, Utah, USA). METHODS: 47 university students volunteered for this cross-sectional study: mean age 20.4 yrs, range 18 to 28 yrs; 23 male, 24 female. Only the measurements from the right eye of each participant were used. Central corneal thickness and mean corneal radius were measured using Scheimpflug biometry and corneal topographic imaging respectively. IOP and PA measurements were made with the OBFA pneumatonometer. Axial length was measured using A-scan ultrasound, due to its known correlation with these corneal parameters. Stepwise multiple regression analysis was used to identify those components that contributed significant variance to the independent variables of IOP and PA. RESULTS: The mean IOP and PA measurements were 13.1 (SD 3.3) mmHg and 3.0 (SD 1.2) mmHg respectively. IOP measurements made with the OBFA pneumatonometer correlated significantly with central corneal thickness (r = +0.374, p = 0.010), such that a 10 microm change in CCT was equivalent to a 0.30 mmHg change in measured IOP. PA measurements correlated significantly with axial length (part correlate = -0.651, p < 0.001) and mean corneal radius (part correlate = +0.459, p < 0.001) but not corneal thickness. CONCLUSIONS: IOP measurements taken with the OBFA pneumatonometer are correlated with corneal thickness, but not axial length or corneal curvature. Conversely, PA measurements are unaffected by corneal thickness, but correlated with axial length and corneal radius. These parameters should be taken into consideration when interpreting IOP and PA measurements made with the OBFA pneumatonometer.

Adolescent↗

PubMed2007

Curve of amniotic fluid index measurements in low-risk pregnancy.

OBJECTIVES: To establish a curve of amniotic fluid index [AFI] measurements from the 20th to the 42nd week of pregnancy. METHODS: A prospective and descriptive study was performed, in which an independent sample of 2,868 low-risk pregnant women were studied using routine ultrasound, including fetal biometry and measurement of AFI. Data were analysed using multiple linear regression, and constructing a curve using 2.5th, 10th, 50th, 90th and 97.5th percentiles of the AFI measurements, according to gestational age, and after submitting values to smoothing process using quadratic polynomial adjustment. RESULTS: There was a significant variation in AFI measurements at the different gestational ages. The 50th percentile remained practically constant at approximately 150 mm between the 20th and 33rd week, after which there was a decline in volume, which became evident after the 38th week. At the 40th week, the 10th percentile was around 62 mm and the 2.5th percentile around 33 mm. CONCLUSIONS: The curve of percentiles of AFI measurements in low-risk pregnant women showed significant decrease with gestational age, especially after the 33rd week. These data should be validated for a diagnosis of increased or decreased volumes of amniotic fluid at specific gestational ages.

Adolescent↗

PubMed2004

A questionnaire study of women's views regarding the effectiveness of serum Down screening in north west Wales.

Questionnaires were circulated to 300 women awaiting mid-trimester anomaly scanning in north west Wales to determine women's views of the adequacy of counselling, availability of pretest scanning, method of receiving test results and whether the Down screening process in general was acceptable. Seventy-five per cent of respondents had serum Down screening; 80.3% of women agreed or strongly agreed that counselling prior to antenatal testing for Down syndrome was adequate; 80.7% of women agreed or strongly agreed that the consequences of a high risk result were explained before testing; 88.7% of women agreed or strongly agreed that they had a choice as to whether screening was accepted or not; 81.7% of women agreed or strongly agreed that they were involved in the decision process; and 40.0% of women having Down testing did not have previous ultrasound biometry. Routine pretest ultrasound scanning remains a resource priority.

Adult↗

PubMed2006

Utility of Doppler velocimetry in correlating with outcomes in severe discordant twins.

Twin birth weight discordance is associated with poor perinatal outcome. Three cases of severe discordant twins were serially assessed by ultrasound biometry and the Doppler ultrasonography of both the middle cerebral artery (MCA) and umbilical artery (UA) to measure pulsatility index (PI), resistance index (RI), and the systolic and diastolic ratio (S/D ratio). The birth weight discrepancies in three cases are 38%, 69% and 68%, respectively. Doppler velocimetry revealed a discrepancy in the S/D ratio of MCA and UA more than 15%. Absent end-diastolic flow, or the brain sparing effect, was noted in three small twins. Cerebral-umbilical S/D ratio (CUR) (MCA/UA) of the twins was above 1 in large ones and below 1 in small ones. The small twin in case 3 expired after delivery. In conclusion, if the CUR of the S/D ratio of the fetus is below 1, the prognosis might be poor and fetal weight discordancy might be progressively larger.

Birth Weight↗

PubMed2006

An investigation into the applicability of customised charts for the assessment of fetal growth in antenatal population at Blackburn, Lancashire, UK.

The antenatal population at Blackburn, Lancashire, UK is diverse, with 35% non-Caucasian, mainly of Indo-Pakistani origin. The department currently uses standard growth charts, based on the Caucasian population for assessment of fetal growth. This study was designed to ascertain whether the use of customised growth charts (CGCs) in our antenatal population can improve the identification of true growth restriction and decrease the number of interventions for suspected growth restriction. CGCs were generated for 109 women induced for intrauterine growth retardation (IUGR) and fetal biometry plotted. The centile range on the CGC was compared with standard charts. Results showed that women of Indian and Pakistani origin were greatly over-represented in the study group. A total of 58% of the cases induced for IUGR had babies within the normal range on CGC. Had CGC been used 54.4% of growth scans and 53% of antenatal day unit (ADU) appointments for fetal monitoring would have been unnecessary. Our study shows that introduction of CGC in our practice could lead to a very significant reduction in interventions for suspected growth restriction.

England↗

PubMed1998

'Expert' analysis of menstrual and ultrasound data in pregnancy--gestational dating.

The expected date of delivery (EDD) using a precise ultrasound day rule was compared with the scan EDD alone in 219 singleton pregnant women who were certain of their last menstrual period, and booked in the obstetric department of a district general hospital. The system compared the ultrasound biometric measurement with the normal range of a published chart of fetal size and, using the day rule concept, the final EDD selected by an 'expert' computer system. Statistical analysis using similar methods as in other published studies showed that the 'expert' system correlated with the actual date of the onset of spontaneous labour at least as well as scan dates alone. Menstrual data should not be rejected in favour of ultrasonic biometry in all cases and a computer system using a precise day rule should be a valuable addition to computerised maternity databases and ultrasound machines.

Journal Article↗

PubMed1998

A multiplicative statistical model predicts the size distribution of unruptured intracranial aneurysms.

A statistical model for characterizing the erratic nature of aneurysm evolution is developed and tested. This model is based upon a multiplicative hypothesis, whereby it is theorized that the progressive changes in the size of a given aneurysm are determined by random multipliers. Such a model would predict that within a large population of aneurysms, a lognormal histogram for aneurysm sizes would occur (i.e. the logarithms of aneurysm size would have a normal distribution). When applied to previously published clinical data of unruptured aneurysms by Crompton (1966) and McCormick et al. (1970), the model is found to adequately describe both sets of data. The methods introduced in this paper illustrate the utility of incorporating statistical and clinical insights with fundamental biometry for studying the complex phenomena of aneurysm growth and rupture.

Aneurysm, Ruptured↗

PubMed2005

Methods for a population-based study of myopia and other eye conditions in school children: the Sydney Myopia Study.

PURPOSE: The Sydney Myopia Study will establish the prevalence of myopia and other eye diseases in a large representative sample of Sydney school children. It will also examine the relationship between myopia and potential modifiable risk factors and will assess potential gene-environment interactions by examining parents and siblings. METHODS: The target population is a stratified random cluster sample of 1750 Year 1 (age 6 years) and 1500 Year 7 (age 12 years) students from Sydney metropolitan schools. Procedures (comprehensive parent-administered questionnaire and examination) involve standardized protocols to allow for comparison with international population-based data. Examinations include a detailed assessment of visual acuity, cover testing for strabismus, identification of amblyopia, slit-lamp examination, non-contact ocular biometry and cycloplegia (cyclopentolate) followed by autorefraction, optical coherence tomography, retinal thickness measurement, digital mydriatic retinal photography and aberrometry. CONCLUSIONS: The Sydney Myopia Study design and methodology will ensure valid findings on ocular development and health in a large representative sample of Sydney school children, for comparison with other population-based refraction data.

Adolescent↗

PubMed2004

A novel KERA mutation associated with autosomal recessive cornea plana.

PURPOSE: To report a novel KERA mutation associated with autosomal recessive cornea plana in members of a nuclear family and to describe their ophthalmic phenotypes. METHODS: Ophthalmic examination, biometry, and direct sequencing of KERA. RESULTS: Five of the 6 siblings were affected and had small flat corneas, variable anterior chamber depths, and short axial lengths. The remaining brother and the 2 parents had normal ophthalmic examinations. Genetic testing revealed a novel homozygous nonsense mutation in exon 3 [937C>T] in the clinically affected individuals. The clinically unaffected parents were confirmed as carriers. The clinically unaffected sibling had no KERA mutation. This mutation leads to replacement of an arginine by a stop codon at position 313 of keratocan protein. CONCLUSIONS: This novel point mutation in KERA is the fourth thus far described. The ocular phenotype is characteristic of autosomal recessive cornea plana.

Adolescent↗

PubMed2006

Three-dimensional multiplanar ultrasound in a limb-body wall complex fetus: clinical evidence for counseling.

A rare dysmorphologic fetal anomaly at the 17th week of gestation was suspected during a second trimester routine scan for fetal and maternal screening data. First findings were significant for a severe abdominal wall defect, limb and foot compromised positions. Fetal biometry was appropriate in biparietal diameter and head circumference measurements; the long upper bones were normal both for length and development. The patient was referred to a prenatal unit to complete the sonographic diagnosis. Two- and three-dimensional sonographic investigations were performed and techniques were complementary for fetal maldevelopment specification. Limb-body wall complex with lumbosacral spine torsion and lower limbs with severely abnormal features were identified. With 2D color Doppler, a heart defect was confirmed and the umbilical cord was missing from the amniotic cavity. An invasive procedure by amniocentesis was made to ascertain alpha-fetoprotein levels and fetal karyotype. Following parental counseling, pregnancy was terminated and feto-pathological examination confirmed the sonographic diagnosis. The 17-week fetus affected by limb-body wall complex is reported herein; 2D and 3D scans of the fetus identified organ displacement due to a combination of very early events.

Abdominal Wall↗

PubMed2004

Ultrasound evaluation of intrauterine growth restriction therapy by a nitric oxide donor (L-arginine).

OBJECTIVE: There are numerous methods available of treating intrauterine growth restriction but their results are still not satisfactory. Currently, we are conducting a research project whose main aim is based on the use of the nitric oxide (NO) donor L-arginine in growth restriction therapy. The main aim of this study was the ultrasound evaluation of the efficacy of this therapy based on biometric measurements (the estimated fetal weight) compared with the estimated weight of newborn children. STUDY DESIGN: The investigated group comprised two randomly chosen groups of pregnant women with ultrasound-diagnosed intrauterine growth restriction (biometry < 10th centile for gestation age): 78 patients were treated by L-arginine 3 g daily orally for 20 days; and 30 patients, not treated, acted as the control group. RESULTS: The ultrasound estimation of fetal weight at the start and at the end of the treatment showed a mean increase of 642 g (SE 90 g) using the Shepard method, and 648 g (SE 94 g) using the Hadlock method, respectively. By comparison, within the control group a mean value increase of 395 g (SE 77 g) was found, using the Shepard method, and 404 g (SE 82 g) using the Hadlock method, respectively. There was a significant statistical difference when comparing the estimated fetal weight increase in both methods: p=0.008 for the Shepard calculation and p=0.012 for the Hadlock calculation. The weight of the newborn infants was also evaluated: in the treated group the mean value was 2823 g (SE 85 g) and in the untreated group the mean value was 2495 g (SE 147 g). There was a significant (p=0.027) difference, showing a positive effect of the treatment on the weight of newborns. In the treated group the percentage of growth-retarded newborns was 29% while in the untreated group it was 73%. A significant difference has been found (p < 0.01) between both of the groups of newborns. CONCLUSIONS: The ultrasound evaluation of the estimated fetal weight and the birth weight of the newborns showed an improvement: there was an acceleration of fetal development in the L-arginine-treated group of pregnant women as compared with the untreated group. The ultrasound evaluation of the estimated fetal weight is a good diagnostic tool, properly monitoring the efficacy of the L-arginine treatment of the growth-retarded fetuses.

Adult↗

PubMed2001

The cerebroplacental Doppler ratio and neonatal outcome in diamnionic monochorionic and dichorionic twins.

OBJECTIVE: Neonatal outcome in twins was studied in relation to the cerebroplacental ratio (CPR). METHODS: Seventy-five infants from twin pregnancies with fetal Doppler data obtained within 3 weeks of delivery were candidates for study (23 infants from diamnionic monochorionic and 52 infants from diamnionic dichorionic twin pregnancies). Multivariate regression analyses were expanded to include 114 twin infants (34 diamnionic monochorionic and 80 diamnionic dichorionic twins). Patients with twin transfusion syndrome were excluded from analysis in the monochorionic group. Targeted ultrasound examination with biometry was performed, and Doppler resistance index (RI) of the umbilical artery (UA) and the middle cerebral artery (MCA) were obtained, and the CPR, a measure of blood flow redistribution, was calculated. Outcome variables included major complications, growth restriction, days of ventilator and oxygen use, days in the neonatal intensive care unit and length of stay. RESULTS: The CPR was correlated more highly with adverse outcomes such as birth weight, special-care nursery days and length of stay than were the UA RI or the MCA RI. The CPR was significantly lower in monochorionic compared with dichorionic twins (1.12 vs. 1.27, p = 0.01). Multivariate regression analyses conducted separately on each twin group also demonstrated that CPR was superior to UA RI and MCA RI in predicting length of stay and restricted growth. Among the Doppler variables, the CPR showed the highest sensitivity for growth restriction (67%). CONCLUSION: In twins, CPR was superior to UA RI and MCA RI in predicting adverse neonatal events.

Adult↗