Kourosh Sabri

Course, complications, and outcome of juvenile arthritis–related uveitis

PURPOSE To describe the clinical features of uveitis in patients with juvenile idiopathic arthritis (JIA). METHODS Retrospective chart review of a subset of 1,081 consecutive JIA patients who were younger than 18 years of age and had uveitis, with a minimum of 1-year follow-up at a single center. RESULTS One hundred forty-two patients (13.1%) developed uveitis after a mean follow-up of 6.3 years (range, 0.10-23.2). Uveitis types were chronic anterior (97/142, 68.3%), acute anterior (23/142, 16.2%), recurrent anterior (17/142, 12%), and panuveitis (5/142, 3.5%). Uveitic complications were observed in 37.3% of cases (53/142) and 32.5% of eyes (74/228). When we compared uveitic eyes with complications to uveitic eyes without complications, we found the following significant differences: time interval from diagnosis of JIA to diagnosis of uveitis was shorter (mean, 1.3 years vs. 2.2 years; p = 0.003) and use of oral prednisone was greater (59.1% vs 15.6%; p < 0.0001) in the eyes with complications. Twenty-one children (21/142, 14.8%) with uveitis underwent a total of 62 ocular surgeries. Good visual acuity (20/40 or better) was found in 90.8% of eyes (159/175) and in both eyes of 87% of cases (94/108), impaired visual acuity in 6 eyes of 4 cases (6/175, 3.4%), and blindness in 10 eyes of 10 cases (10/175, 5.7%). Only 2 patients had reduced visual acuity in both eyes. Surgery was the single most important risk factor for reduced visual acuity at the last follow-up (p = 0.0086). CONCLUSIONS Most uveitic eyes with JIA achieved good visual outcome despite uveitic complications.

A frequency domain-based approach for blind MIMO system identification using second-order cyclic statistics

This article introduces a new frequency domain approach for either MIMO system identification or source separation of convolutive mixtures of cyclostationary signals. We apply the joint diagonalization algorithm to a set of cyclic spectral density matrices of the measurements to identify the mixing system at each frequency bin up to permutation and phase ambiguity matrices. An efficient algorithm to overcome the frequency-dependent permutations and to recover the phase, even for non-minimum-phase channels, based on cyclostationarity is also presented. The new approach exploits the fact that each input signal has a different and specific cyclic frequency. Simulation examples are presented to illustrate the effectiveness of this approach.

National survey of corneal abrasion treatment.

Purpose To survey the different methods used in the management of corneal abrasions (including iatrogenic cases) nationally.Method A questionnaire survey of all 162 ophthalmic units in the UK was carried out in 1997.Results The response rate was 134 of 162 (83%). The majority of units do not have an established policy for the treatment of corneal abrasions. Topical antibiotic alone and antibiotic together with a cycloplegic are the commonest immediate treatments, whilst the most common treatment course is topical antibiotic. Padding and patient follow-up is practised some of the time by most units and all of the time by the remaining minority. Use of a soft bandage contact lens is uncommon. There is no statistically significant difference (p<0.05) between the policy-holders and non-policy-holders in their use of the various topical regimes, padding and soft bandage contact lens.Conclusion The traditional trio of topical antibiotic, cycloplegic and padding is still the mainstay of corneal abrasion treatment amongst units nation-wide. However, there is a lack of reproducible scientific evidence to support this treatment. Larger randomised trials looking at the efficacy of the different treatment options are needed.

National variations in retinopathy of prematurity screening criteria in Canada: existent guidelines and actual practice patterns

OBJECTIVE To survey the current inclusion criteria used for retinopathy of prematurity (ROP) screening across tertiary level 3 neonatal intensive care units (NICUs) in Canada. PARTICIPANTS Clinical directors from 29 level 3 NICUs in Canada. METHODS Survey of all 29 level 3 NICUs in Canada in September 2010. The survey inquired about the current ROP screening criteria in use in each centre including which neonates are enrolled in the screening program and the timing of when screening begins. The survey was sent via email to the clinical directors at each site. Nonrespondents were contacted by telephone. RESULTS In total, 23 centres replied, representing a 79% response rate with the survey. Seven different ROP screening inclusion criteria were found to be in use, although one of the centres did not have a clear inclusion protocol. The variation between centres was significant, with some using a combination of birth weight and gestational age and others using birth weight or gestational age alone as their criterion. There was also variation in the timing of initial eye examinations, with 8 different criteria currently in use. Discrepancies were also found among treatment patterns at the centres. CONCLUSIONS Despite the publication of updated Canadian guidelines in 2000, there continues to be significant variation in the actual inclusion criteria being used across the country. Therefore, a need exists for comprehensive, evidence-based Canadian guidelines to optimize the screening inclusion criteria for ROP.

Assessing accuracy of non–eye care professionals as trainee vision screeners for children

OBJECTIVE To determine the level of agreement between non-eye care trainees and a trainer (ophthalmologist) in a vision screening program. DESIGN Prospective, observational study carried out in 3 phases (Phase I-III). PARTICIPANTS Study population included 1228 children, aged 6-14 years, at 5 elementary schools in the city of Hamilton. METHODS In Phase I, 1228 children were screened by the trainee screeners, of which 273 children failed the vision testing. Of these 273 children, 170 consented to enrolment into Phase II and were examined by an ophthalmologist, who confirmed that 105 of these children were true positives. On retesting (Phase III), the ophthalmologist passed 158 of the 163 randomly selected children who passed in Phase I. RESULTS Overall, trainee screeners had a sample sensitivity of 95.5% and sample specificity of 70.8% in detecting children who should fail vision screening. When we used the positive and negative prediction values obtained, 198 of the 1228 children had vision impairment-providing an estimated prevalence of 16.1%, or 161 children per 1000 population. CONCLUSIONS Non-eye care professionals can be trained to an acceptable degree of accuracy to perform certain vision screening tests on children. Such screening methods may be a useful approach to address existing gaps in provision of eye care for many Canadian children, thereby ensuring that all children receive timely vision screening.

Rare case of optic pathway glioma with extensive intra-ocular involvement in a child with neurofibromatosis type 1

We present a case of a 3-year-old girl with a positive family history of neurofibromatosis type-1 (NF1) presented with best corrected visual acuity of 20/40 in the right eye and <20/400 in the left eye. External ocular examination revealed left eye proptosis of 3 mm, grade II left relative afferent pupillary defect and full range of ocular motility with no strabismus. Slit lamp examination revealed iris lisch nodules bilaterally. Dilated fundus examination of the right eye was normal. Left eye disclosed a large mass extending from the optic nerve head, with associated subretinal fluid. There was neovascularization at the optic disc as well as a superior retinal hemorrhage. Computed tomography of brain/orbits showed an enlarged left optic nerve with a large mass at the optic nerve head, with no evidence of calcification. In addition, a large left optic pathway glioma (OPG), multiple hamartomas within the brain and a smaller low-grade right OPG was also reported. The remarkable feature of our case is the rare intraocular optic nerve involvement of the OPG. Early and regular ophthalmological assessment of all NF1 suspect/confirmed cases is of paramount importance in order to detect OPG early, resulting in timely intervention and salvage of vision.

On blind MIMO system identification based on second-order cyclic statistics

This letter introduces a new frequency domain approach for either MIMO System Identification or Source Separation of convolutive mixtures in cyclostationary context. We apply the joint diagonalization algorithm to a set of cyclic spectral density matrices of the measurements to identify the mixing system at each frequency up to permutation and phase ambiguity matrices. An efficient algorithm to overcome the frequency dependent permutations and to recover the phase, even for non-minimum-phase channels, based on cyclostationarity is also presented. The new approach exploits the fact that each input has a different and specific cyclic frequency. A comparison with an existing MIMO method is proposed.

Effect of anesthesia on intraocular pressure measurement in children

Measurement of the intraocular pressure (IOP) is central to the diagnosis and management of pediatric glaucoma. An examination under anesthesia is often necessary in pediatric patients. Different agents used for sedation or general anesthesia have varied effects on IOP. Hemodynamic factors, methods of airway management, tonometry technique, and body positioning can all affect IOP measurements. The most accurate technique is one that reflects the awake IOP. We review factors affecting IOP measurements in the pediatric population and provide recommendations on the most accurate means to measure IOP under anesthesia based on the present literature.

Elbow splinting as a method to increase patching compliance in amblyopia therapy

PurposeThe purpose of the study was to evaluate the feasibility and acceptability of utilizing elbow splints as a method of increasing amblyopic patching compliance in pediatric ophthalmology patients who fail to comply with prescribed patching regimens.Patients and methodsPatients <6 years of age who were not adhering to pre-specified patching guidelines were prescribed elbow splints in order to increase patching compliance at the discretion of a pediatric ophthalmologist. If the child was non-compliant (patching <50% of specified time or consistently removing patch), parents were asked to try using the elbow splints until patching compliance was achieved. Non-parametric Wilcoxon signed-rank tests were used to compare patching time pre- and post-splints.Results41/48 children who were prescribed elbow splints to increase patching compliance for amblyopia were included for analysis. Seven children were excluded due to patching and splints being prescribed at the outset (n=4), and for not using the splinting intervention (n=3). Median age at being prescribed elbow splints was 37 (12–68) months. Mean daily patching prior to splints was 1.5±1.7 h, whereas mean prescribed daily patching was 4.95±1.5 h. Following splinting, 34/41 (83%) became compliant with patch alone, and visual acuity increased in 39/41 (95%) patients, with no patients developing amblyopia in the fellow eye. Median amount of time splints was required to improve compliance was 7 (1–240) days.ConclusionElbow splinting seems to be a viable alternative method to increase pediatric amblyopic patching compliance when patching alone fails to achieve satisfactory compliance.

Gear Signal Separation by Exploiting the Spectral Diversity and Cyclostaionarity

This paper deals with the problem concerning the framework of rotating machines diagnostics by using signal processing advanced tools and more precisely blind source separation (BSS) methods. An application on gear box is given, the objective is to separate gear mesh signals corresponding to each reducers wheel. It enables us to diagnose and separate each defect in the event of degradation. The proposed method exploits the information redundancy around the meshing frequency and its harmonics resulting from cyclostationarity properties. This redundancy allows us to separate the contribution of each wheel from only one sensor, by tacking advantage of the non-uniformity of the mechanical structure frequency response (MSFR) connecting the exciting source to the sensor