Spirochetal uveitis.
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Eye Infections, Bacterial↗
Biomedical subjects
Jenny E Hong
Publications and source records attributed to Jenny E Hong.
Endocanalicular laser dacryocystorhinostomy analysis of 118 consecutive surgeries.
PURPOSE: To describe the outcomes of endocanalicular laser dacryocystorhinostomy (ECL DCR) for patients with nasolacrimal duct obstruction (NLDO). DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: One hundred eight consecutive patients who underwent ECL DCR. METHODS: The records of the patients who underwent ECL DCR at 1 of 2 academic centers were reviewed and the data analyzed. MAIN OUTCOME MEASURES: Success was defined as the resolution of symptoms or unobstructed lacrimal irrigation. RESULTS: One hundred eighteen consecutive ECL DCR surgeries performed on 108 patients between June 1997 and June 2003 were reviewed, excluding 6 lost to follow-up. Endocanalicular laser DCR was the initial surgical intervention for all cases except 6 that had previously undergone surgery (external or endonasal DCR) at outside hospitals. Twenty-seven of the surgeries were considered failures on the basis of recurrent epiphora or discharge, or reflux on nasolacrimal irrigation. One of the failures was permanently corrected with balloon dacryoplasty. Nine of the other failures had a repeat procedure, with 7 remaining patent after one repeat procedure and an additional one remaining patent after a third procedure. All 6 ECL DCR procedures that were performed after external or endonasal DCR at an outside institution remained patent. Among the 102 initial lacrimal surgeries in this series, there was a 73.6% success rate. The overall success, including repeat procedures, was 81.5%. The success of this technique as a repeat procedure after previous external, endonasal, or ECL DCRs was 87.5%. CONCLUSIONS: Endocanalicular laser DCR offers a minimally invasive alternative procedure for the treatment of NLDO. In our series, the success rates are comparable to those previously reported. The technique had a high success rate when used to treat recurrent NLDO after previous lacrimal surgery.
Adolescent↗
Visual field defects and multifocal visual evoked potentials: evidence of a linear relationship.
OBJECTIVE: To determine the relationship between spatially localized multifocal visual evoked potentials (mfVEPs) and Humphrey visual fields (HVFs) in patients with unilateral field defects. METHODS: Humphrey visual fields and mfVEPs were obtained from 20 patients with unilateral field losses due to either ischemic optic neuropathy or glaucoma. Monocular mfVEPs were obtained for each eye. The amplitude of the mfVEP responses was calculated using root-mean-square and signal-noise ratio measures. Estimates of the HVF loss in the same regions of the field used for the mfVEP were obtained by interpolating the 24-2 HVF data. RESULTS: Monocular mfVEP amplitude decreased with HVF loss, although small mfVEP signals were not uniquely associated with poor fields. On average, the monocular mfVEP was indistinguishable from noise for field losses between -5 and -10 dB, and good monocular mfVEP amplitudes were never associated with extensive visual field loss. The interocular ratio of the mfVEP amplitudes correlated well with the difference between the HVF values of the 2 eyes, and this correlation improved with increased signal-noise ratio. CONCLUSIONS: The monocular and interocular results were consistent with a linear relationship between the amplitude of the signal portion of the mfVEP response and linear HVF loss. One way to produce this relationship would be if both the signal in the mfVEP and linear HVF loss were linearly related to the percentage of local ganglion cells lost. The clinical limitations of the mfVEP technique can be understood by taking the signal-noise ratio, and the linear model proposed herein, into consideration.
Adult↗
A signal-to-noise analysis of multifocal VEP responses: an objective definition for poor records.
Sixty local VEP records, called the multifocal VEP (mfVEP), can be obtained over a wide retinal area. From subject-to-subject, from day-to-day, and from location-to-location, these records can vary in quality presenting a challenge to quantitative analyses. Here three procedures are described for specifying the quality of mfVEP recordings in terms of signal-to-noise ratios. Monocular mfVEPs were recorded in two, 7-min runs. A '2-run signal-to-noise ratio' (2rSNR) was obtained as [RMS(RunA+RunB)]/[RMS(RunA-RunB)]-1, where RMS is the root-mean-square amplitude of the response over the period from 45 to 150 ms (signal window). Two 'noise-window signal-to-noise ratios' were obtained with the same numerator as the 2rSNR but with the denominators based upon the RMS of a signal-free window from 325 to 430 ms. In one case, inSNR, the denominator was the RMS of the record's noise window and in the other case, mnSNR, the denominator was the mean of the RMS amplitudes of all the signal-free noise windows for the subject. The SNRs were related to false-positive rates (i.e., detecting a signal when none was present) by recording mfVEPs with some of the sectors of the display occluded. In particular, the outer three rings (36 sectors) of the display were occluded so that only noise was recorded; false-positive rates for different values of SNR were calculated. The 2rSNR had the highest false-positive rate largely due to alpha in the records of some subjects. The mnSNR had a lower false-positive rate than did the inSNR because there was little correlation between the RMS of the noise in the signal-free window and the RMS of the noise within the signal window. Use of the mnSNR is recommended over the 2rSNR, especially where alpha contamination can not be eliminated. Ways to improve the SNR of the records are discussed.
Adult↗
Quantifying the benefits of additional channels of multifocal VEP recording.
For some individuals and for some locations, multifocal visual evoked potentials (mfVEP) may be too small or appear 'too noisy' to be reliably measured. By adding electrodes, especially electrodes placed lateral to the midline, and by recording with multiple channels, the amplitude of the signal can be increased in some field locations. However, the addition of electrodes involves certain costs; the set-up time is longer and the data analysis more time consuming and complex. The objective of this study was to assess the benefits of adding electrodes by quantifying these benefits using a signal-to-noise measure. In addition to the typical midline placement of electrodes, two electrodes were placed 1 cm above and 4 cm lateral to the inion on each side. This allowed for 3 channels of recording and 3 additional, derived channels. The mfVEPs were recorded with a 60 sector, pattern-reversing display presented to one eye. Two 7 min records were obtained from 14 individuals with no known visual problems. The two records were averaged and a signal-to-noise (SNR) measure was obtained for every response from all 6 channels. For each sector of the display and each subject, the benefits of additional electrodes were quantified by comparing the SNR from the traditional midline channel to the best SNR from amongst the 6 channels. The number of responses exceeding any given criterion SNR value was increased with the additional channels. For example, 79% of the responses for the typical midline channel exceeded a SNR of 0.6 (a false positive rate of about 2.5%) and this increased to 93% when the best SNR value was used. As expected, summing the mfVEP responses from contiguous sectors also increased the SNR values. Additional electrodes and multiple channels of recording substantially improve the quality of the mfVEP records and the SNR measure provides a useful metric for assessing these benefits.
Adult↗