Search PubMed⌕ Search

Biomedical subjects

Alex V Levin

Publications and source records attributed to Alex V Levin.

At least 37 records · Page 2Linked to original sources
PubMed2004

Early postoperative refractive outcomes of pediatric intraocular lens implantation.

PURPOSE: To evaluate the refractive outcome using 5 intraocular lens (IOL) calculation formulas to determine which best predicts refraction after pediatric cataract surgery. SETTING: The Hospital for Sick Children, Toronto, Ontario, Canada. METHODS: This study comprised a review of the charts of 158 consecutive patients aged 2 to 17 years old who were operated on by 1 of 2 staff surgeons between May 1992 and April 2000. The surgeons performed a total of 206 cataract extractions with primary or secondary IOL implantation. The measured outcome was the actual refraction 2 to 6 months postoperatively versus the target refraction. Two regression formulas (SRK, SRK II) and 3 theoretical formulas (Holladay 1, Hoffer Q, SRK/T) were used to predict refractive outcome based on preoperative axial length, corneal curvature, IOL power, and the IOL A-constant provided by the manufacturer. RESULTS: Forty-nine patients (59 IOL implantations) with available data 2 to 6 months after surgery were studied. Also analyzed were data from a subset of 31 patients (34 IOL implantations) with available data 2 to 3 months after surgery. There was poor to moderate agreement between the predicted and actual postoperative refractions using the SRK formula (intraclass correlation coefficient [ICC] = 0.50/0.04 [2- to 3-month follow-up/2- to 6-month follow-up]) and good or fair agreement using the other formulas (ICC from 0.60/0.24 for SRK II to 0.67/0.37 for Hoffer Q). The mean difference between the predicted and actual postoperative refractions with all formulas ranged from 1.06 to 1.22 diopters (D)/1.35 to 1.79 D (median 0.81 to 0.99 D/0.94 to 1.40 D; range 3.03 to 5.57 D/6.75 to 9.21 D). Using Holladay 1 and SRK, 9% to 18%/23% to 39% eyes were more than +/-2.00 D off the target outcome refraction. CONCLUSIONS: All 5 IOL power calculation formulas were unsatisfactory in achieving the target refraction. This finding may have implications for predicting long-term outcomes, interpreting previous reports of refractive outcomes, and obtaining preoperative informed consent in a clinical setting.

Adolescent↗
PubMed2004

Retinal hemorrhages in type I osteogenesis imperfecta after minor trauma.

OBJECTIVE: To report 3 patients with type I osteogenesis imperfecta (OI) who developed retinal hemorrhages and subdural hematomas after minor trauma. DESIGN: Observational case series. METHOD: Children with OI who developed retinal hemorrhages after minor trauma were identified through an international e-mail-based mailing list for professionals with an interest in child abuse. RESULTS: Three patients with type I OI who presented to the emergency department after a short fall were identified. Clinical evaluation included pediatric and ophthalmic examination. Investigations included complete blood count, coagulation profile, computed tomography of the brain, and a skeletal survey. Ophthalmologic examination revealed retinal hemorrhages in all the children. In the first patient, these were flame shaped and located in the posterior pole of the left eye. The second patient had vitreous and retinal hemorrhages in both eyes. The third patient had scattered intraretinal hemorrhages in both eyes. Computed tomography demonstrated a subdural hematoma in all of the patients and, in patient 2, a simple parietal skull fracture. The child protection teams that investigated the cases believed the explanations offered for the injuries to be plausible, and a diagnosis of accidental injury was made in all 3 patients. CONCLUSION: This is the first report of retinal hemorrhages and subdural hematoma after trivial trauma in patients with type I OI. The collagen defects underlying this disorder of bone and connective tissue may predispose patients with type I OI to retinal hemorrhages and subdural hematomas after minor trauma.

Accidental Falls↗
PubMed2004

Characterization and prevalence of PITX2 microdeletions and mutations in Axenfeld-Rieger malformations.

PURPOSE: Mutations of the homeodomain protein PITX2 produce Axenfeld-Rieger (AR) malformations of the anterior chamber, an autosomal dominant disorder accompanied by a 50% risk of glaucoma. Twenty-nine mutations of PITX2 have been described, with a mutational prevalence estimated between 10% and 60% in AR. In the current study, the possible role of altered PITX2 gene dosage in the etiology of AR was investigated. Gross gene deletions and duplications should alter PITX2 activity analogously to hypomorphic and hypermorphic mutations, respectively. METHODS: Sixty-four patients with AR, iridogoniodysgenesis (IGD), iris hypoplasia (IH), or anterior segment dysgenesis (ASD) were screened for PITX2 mutations by sequencing. PITX2 gene dosage was concurrently examined in these patients by real-time quantitative PCR. Microsatellite markers were used to map 4q25 microdeletions at a contig scale, as well as for haplotype analysis in an extended AR kindred. An additional 27 patients with other assorted ocular phenotypes were evaluated by similar methods, amounting to a total of 91 cases analyzed. RESULTS: Three novel mutations of PITX2 (4.7%) were identified among 64 patients with AR, IGD, IH, or ASD. Deletions of PITX2 were as frequent as mutations in our sample. Chromosome 4q25 microdeletions were physically mapped relative to several microsatellite markers in each patient. Cosegregation of AR and a PITX2 deletion was demonstrated in an extended kindred. CONCLUSIONS: Point mutations and gross deletions of PITX2 appear to produce an equivalent haploinsufficiency phenotype. Quantitative PCR is an efficient means of detecting causative PITX2 deletions in patients with AR and may increase the detection rate at this locus.

Anterior Eye Segment↗
PubMed2004

Defining the pathogenicity of optineurin in juvenile open-angle glaucoma.

PURPOSE: Juvenile open-angle glaucoma (JOAG) differs from primary open-angle glaucoma in that it is usually a more severe phenotype and has an earlier age of onset. Optineurin was recently associated with a variant of POAG that is characterized by intraocular pressure within normal limits: normal-tension glaucoma. The present study tested whether OPTN sequence changes play a role in early-onset glaucoma characterized by elevated intraocular pressure. METHODS: Sixty-six patients with JOAG characterized by high intraocular pressure were screened for mutations. Mutational analysis was performed with a combination of restriction enzyme digestion, single-strand conformation polymorphism, and direct sequencing. The effects of select changes on exon splicing were assessed using bioinformatic modeling approaches and RT-PCR. RESULTS: Ten sequence changes were identified, of which H486R was strongly suggestive of pathogenicity. H486R represents the first reported OPTN mutation associated with JOAG. Also, L41L is proposed to confer an increased susceptibility to the development of JOAG. Most of the other sequence changes observed were not thought to be biologically significant. The frequency of the previously reported M98K allele was not increased in the JOAG population studied but showed the previously reported skewed distribution in the POAG study population. The changes identified were not shown to affect the splicing machinery. CONCLUSIONS: The results of this work support the hypothesis that mutations in OPTN are not specifically associated with low-pressure glaucoma, but can play a role in JOAG.

Adolescent↗
PubMed2003

Heterozygous mutations of the kinesin KIF21A in congenital fibrosis of the extraocular muscles type 1 (CFEOM1).

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A. We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.

Amino Acid Sequence↗
PubMed2003

Linkage study between congenital cataracts and five crystallin loci.

Congenital cataracts are a common cause of preventable blindness in children. We studied autosomal dominant congenital cataracts in 38 families and examined linkage between cataract loci and the crystallin genes on chromosomes 2, 11, 17, 21, and 22. We used clinical information to group families with phenotypically similar cataracts and analyzed the genetic data in these groups. Although LOD scores > 3.0 were not obtained, we found some support for linkage to four of the chromosomal regions examined, namely 2q33-35, 17q11.2-12, 21q22.3, and 22q11.2.

Alleles↗
PubMed2003

Challenges of teaching surgery: ethical framework.

Surgeons, trainees, and patients may be uncomfortable with the secrecy that surrounds the process of teaching and learning surgical procedures. Well structured training programs use a system of graded responsibility, supervision, and evaluation to ensure skill development and patient safety. Patient outcomes are generally excellent in training institutions. Disclosure of the role of trainees and their contribution to care enhances trust.

Clinical Competence↗
PubMed2003

Complications in infants undergoing surgery for congenital cataract in the first 12 weeks of life: is early surgery better?

PURPOSE: To determine if there is an association between the timing of surgical intervention for congenital cataract within the first 12 weeks of life and the prevalence of postoperative complications. METHODS: We performed a retrospective review of records from 1990 to 2000 of infants who underwent surgery for congenital cataract within the first 12 weeks of life. Eighty eyes in 55 children were involved with a minimum follow up of 6 months. Bilateral cataracts were present in 25 and monocular cataracts in 30 infants. A limbal approach lensectomy-vitrectomy was performed in all infants. Children with aphakia were rehabilitated with contact lens or glasses. Operative and postoperative complications-including glaucoma, nystagmus, strabismus, retinal detachment, and posterior capsule opacification/secondary membranes-were recorded. Ocular and systemic associations were noted. Statistical analysis was carried out with classification and regression trees (CART). RESULTS: The mean age at the time of surgery was 31.5 +/- 23.3 days (median, 26.5; range, 2 to 84). Mean follow up from the time of surgery was 2.85 +/-1.9 years (median, 2; range, 0.5 to 8). Persistent fetal vasculature (persistent hyperplastic primary vitreous) was present in 14 eyes. One infant with bilateral persistent fetal vasculature had bilateral retinal dysplasia and was excluded from the analysis. Glaucoma developed in 12 infants (22%); nystagmus was present in 18 infants (33%); strabismus developed in 28 infants (52%); and secondary membranes developed in 7 eyes (13%). CART analysis suggests that glaucoma is more prevalent in infants when the surgery was performed between 13.5 and 43 days of life (CART = 0.370); nystagmus when surgery is performed between 48 and 84 days of life (CART = 0.500); strabismus when surgery is performed between 55.5 and 84 days of life (CART = 0.600); and secondary membranes when surgery is performed between 26.5 and 40 days of life (CART = 0.4). CONCLUSIONS: Our data suggest that the first 2 weeks of life comprise the most favorable time for decreasing postoperative complications resulting from surgical intervention for infants presenting with cataracts within the first 12 weeks of life.

Cataract↗
PubMed2003

The Ahmed drainage implant in the treatment of pediatric glaucoma.

PURPOSE: To report the safety and efficacy of Ahmed Glaucoma Valve (New World Medical, Inc., Rancho Cucamonga, California, USA) implantation for the management of pediatric glaucoma in the early and intermediate follow-up period. DESIGN: Consecutive interventional case series. METHOD: A retrospective chart review was conducted on 60 eyes (44 patients, age range at surgery 1.5 months to 16 years, average 6 +/- 4.9 years), with pediatric glaucoma that underwent Ahmed Glaucoma Valve implantation for medically uncontrolled intraocular pressure (IOP) between the years 1995 and 2000. Outcome measures were control of IOP below 21 mm Hg, the need for antiglaucoma medications after surgery, and loss of 2 or more lines of Snellen acuity. Complications were monitored. RESULTS: The postoperative follow-up period for each eye averaged 24.3 +/- 16 months (range, 3 to 60 months). At last follow-up, IOP was controlled in 44 eyes (73%), 11 of which did not need antiglaucoma therapy. Kaplan-Meier life-table analysis showed probability of success with or without medications of 93% (95% confidence interval [CI], 86%-100%), 86% (95% CI, 77%-96%), 71% (95% CI, 59%-87%), and 45% (95% CI, 28%-80%) after 12, 24, 36, and 48 months of follow-up. Average IOP decreased from 32.8 +/- 6.2 before surgery to 16.6 +/- 8.0 postoperatively (P <.0001). The average number of medications used decreased from 4.4 +/- 1.97 to 2.0 +/- 2.0 (P <.0001). Kaplan-Meier survival analysis did not reveal any difference in survival profiles related to specific diagnosis of glaucoma, age (above or below 18 months), or prior surgery. Complications occurred in 30 eyes (50%). Although most resolved or were treated successfully, four patients had severe visual loss during the follow-up. Uveitis was a significant risk factor for tube exposure (Fisher exact test, P =.006). CONCLUSIONS: Ahmed Glaucoma Valve implantation is an effective treatment for pediatric glaucoma, although patients frequently require antiglaucoma medications. However, a high rate of potentially sight-threatening postoperative complications warrants ongoing close follow-up.

Adolescent↗
PubMed2003

Clinical diagnoses that overlap with choroideremia.

PURPOSE: To understand which clinical presentations suggest a diagnosis of choroideremia (CHM). METHODS: Retrospective chart review. Included were patients for whom a clinical diagnosis of CHM was suggested, but either protein analysis or direct sequencing of the CHM gene could not confirm the diagnosis. Clinical presentation, family history and fundus photographs were reviewed. RESULTS: We analyzed protein and DNA samples from members of more than 100 families in which at least 1 member had a clinical diagnosis of CHM. For 26 of these families, the clinical diagnosis of CHM could not be confirmed by laboratory analysis. Relevant clinical information was requested from the referring ophthalmologists so that alternative diagnoses could be considered. Sufficient information was provided for 13 of the 26 families. Four patients were reclassified as having retinitis pigmentosa (RP) from the clinical phenotype; only two clearly had X-linked inheritance. One patient had a syndrome including macular dystrophy, hearing loss, developmental delay and cerebral palsy. One patient was reclassified as having congenital stationary night blindness on the basis of an electronegative electroretinogram and a normal fundus. One patient had hearing loss suggesting Usher syndrome. One patient had signs consistent with cone-rod dystrophy (CRD). Five patients could not be reclassified on the basis of the clinical presentation. CONCLUSION: RP, Usher syndrome and CRD are clinical phenotypes that may overlap with CHM. Clinical features that suggest CHM include severe chorioretinal atrophy with preservation of the macula, X-linked inheritance and retinal changes in a related female.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Ophthalmic assessment of children before renal transplantation.

OBJECTIVE: To evaluate the usefulness of routine ophthalmic examination before renal transplantation in children. METHODS: We reviewed the records of ophthalmic assessments of renal transplant recipients at The Hospital for Sick Children, Toronto, Ont., from January 1989 to June 1996. If abnormalities had been found, we determined whether they had previously been documented, were related to the renal disease or other systemic disease, had required intervention or had affected visual function. We calculated the maximum statistical chance of detecting a meaningful eye problem at the pretransplantation assessment. We also estimated the direct cost of the ophthalmic assessment and the effect, if any, of the findings on the patient's medical management. RESULTS: We included 107 charts. Before the ophthalmic assessment, 32 patients (30%) had known eye problems. The ocular examination detected abnormalities in 46 patients (43%); the abnormalities had not been detected previously in 14 (13%). New, potentially vision-threatening eye disorders were found in 6 (6%) of the patients. No finding affected the short- or long-term management of any patient. CONCLUSION: Children with chronic renal failure had a high prevalence of ocular abnormalities, but most of the abnormalities did not affect visual function. Although ophthalmic assessment before transplantation did not alter the medical management of the renal transplant patients, consultation may be helpful in selected patients, particularly those who are not already under the care of an optometrist or ophthalmologist and those who have a visual complaint.

Adolescent↗
PubMed2003

Congenital eye anomalies.

Any part of the eye and its surrounding tissues may be affected by congenital malformation. Anomalies may occur in isolation, in combination, or as part of a systemic malformation syndrome. Early identification is essential to remove potential obstructions to visual development and to identify potential underlying multisystem disease. Recognition of congenital eye anomalies can also improve parental understanding and genetic counseling.

Cataract↗
PubMed2003

Contact lenses for the treatment of pediatric cataracts.

OBJECTIVE: To evaluate the experiences, attitudes, and perceptions of the caregivers of children with cataracts who were visually rehabilitated with contact lenses. PARTICIPANTS: One hundred twenty-three caregivers of children <8.1 years old treated for unilateral and bilateral cataracts at one pediatric hospital. DESIGN: Survey by questionnaire. INTERVENTION: Primary caregivers were asked to complete an anonymous questionnaire. MAIN OUTCOME MEASURES: Caregiver responses to questions assessing background and demographic and clinical information, as well as perceptions, attitudes, levels of compliance, and anxiety with respect to treatment, were reviewed. Caregivers were also asked to choose between aphakic rehabilitation with contact lenses, aphakic glasses, or intraocular lenses, given various hypothetical scenarios differing in regard to their final visual prognosis, risks of treatment complications, and cost. RESULTS: The response rate was 82.9%. Absolute average stress levels for contact lens use were 1.36 +/- 1.79 and 0.79 +/- 1.48 (scale, 0-5) for insertion and removal, respectively, compared with 4.03 +/- 1.64 and 2.40 +/- 1.92 for cataract surgery and patching therapy, respectively. Although average paired initial resistance to treatment (RT) levels for contact lens insertion and removal on a scale of 0 to 3 were high (2.09 +/- 1.15) and moderate (1.63 +/- 1.20), respectively, final RT levels were significantly lower (1.09 +/- 1.14 and 0.66 +/- 1.07, respectively; P < 0.0001). The vast majority of caregivers chose contact lens use in hypothetical scenarios that depicted realistic expectations for other forms of aphakic rehabilitation. CONCLUSIONS: In our study, contact lenses seemed to be well tolerated by most patients, as assessed by caregivers. Although initial resistance to contact lens use is high, this decreases with time. Relative to other events in the treatment of pediatric cataracts, contact lens use is not a major stressor for most caregivers and patients. This study supports the notion that contact lenses should continue to receive serious consideration as a treatment option for pediatric cataracts.

Aphakia, Postcataract↗
PubMed2003

Nasal endoscopy in the treatment of congenital lacrimal sac mucoceles.

PURPOSE: To determine the incidence of intranasal cysts associated with lacrimal sac mucoceles and the cure rate with nasal endoscopic cyst marsupialization. DESIGN: Interventional case series. METHODS SETTING: University-affiliated teaching hospital. PATIENT POPULATION: Twenty-five infants with non infected or infected lacrimal sac mucoceles or dacrocystitis without obvious mucocele were consecutively enrolled. INTERVENTION PROCEDURES: Management included local lacrimal massage, parenteral antibiotics, and when still symptomatic, nasolacrimal duct probing with concomitant nasal endoscopy. Intranasal cysts identified were marsupialized until the distal end of the nasolacrimal duct probe was visualized. MAIN OUTCOME MEASURES: Presence of intranasal cyst identification and cure rate. RESULTS: Infants were 4 days to 10 weeks old (mean 19 days). Forty-eight percent had a bluish cutaneous mass inferior and lateral to the lacrimal sac. Twenty percent were bilateral. At presentation, 76 percent had dacrocystitis. Fourteen percent had respiratory distress. Only one child responded to medical management. At endoscopy, 23 of 24 infants had ipsilateral intranasal cysts. The one child without nasal cyst had recurrent dacrocystitis and no mucocele. All children with mucocele were cured except one child with residual nasolacrimal duct obstruction. CONCLUSIONS: Lacrimal sac mucoceles were almost always associated with intranasal cysts. Nasal endoscopy is a valuable addition to the treatment plan for lacrimal sac mucoceles not responding to a brief trial of massage or infantile dacrocystitis. To avoid potential complications, we recommend against waiting until infection occurs before proceeding with surgery.

Dacryocystitis↗
PubMed2003

Hypotension and bradycardia in infants after the use of topical brimonidine and beta-blockers.

Brimonidine is a selective alpha-2 adrenergic agonist used to treat glaucoma. There have been several reports of central nervous system depression after its use in infants. We observed rapid-onset bradycardia and decreased blood pressure in addition to central nervous system depression in 2 infants who received concomitant topical brimonidine and beta-blockers.

Administration, Topical↗
PubMed2003

Assessment of extraocular muscles position and anatomy by 3-dimensional ultrasonography: a trial in craniosynostosis patients.

PURPOSE: To determine whether 3-dimensional ultrasonography (3D US) provides information about anatomy and position of extraocular muscles to better guide surgeons approaching strabismus in patients with craniosynostosis who often have anomalous or absent eye muscles. METHODS: The 4 rectus eye muscles were imaged using 3D US for 7 children with craniosynostosis before or after strabismus surgery. Reconstructed 3D images were interpreted as having normal or abnormal anatomy and position, based on comparison with images acquired from 6 normal eyes. Interpretation was validated against the intraoperative findings from strabismus surgery. RESULTS: A total of 34 scans from the study group were used for comparison and validation purposes. Accuracy of anatomical assessments was 85% +/- 12% (percentage +/- confidence interval) and of positional assessments was 62% +/- 16%. Sensitivity and specificity of anatomical assessments was 80% +/- 14% and 88% +/- 10%, respectively. Anatomic anomalies detected by 3D US included excessively thick, thin, scarred and fibrotic, and absent muscles. Sensitivity and specificity of positional assessments was 48% +/- 17% and 85% +/- 12%, respectively. Positional anomalies such as muscle displacement off the normal clock hour axis or posteriorly displaced insertion were also detected. CONCLUSIONS: The 3D US may have an adjunctive role in determining anatomy and position of rectus muscles in patients with craniosynostosis, although it was more accurate in assessing anatomic features rather than positional features of rectus muscles.

Adolescent↗
PubMed2003

Nonophthalmologist accuracy in diagnosing retinal hemorrhages in the shaken baby syndrome.

Nonophthalmologists did not attempt to (36%) or were "unable to" (19%) examine the fundus in 72 children with shaken baby syndrome. When the retina was examined, nonophthalmologists were accurate in recognizing the absence or presence of retinal hemorrhage in 87%. However, false-negative examinations occurred in 13%. Ophthalmology consultation should be an integral part of the evaluation of children with suspected abuse.

Child, Preschool↗