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Biomedical subjects

J T Ernest

Publications and source records attributed to J T Ernest.

At least 37 records · Page 2Linked to original sources
PubMed1996

Charles Bonnet syndrome: an early marker for dementia?

OBJECTIVE: To clarify the neuropsychological function in patients with Charles Bonnet Syndrome. DESIGN: Control group comparison study. SETTING: University of Chicago Hospitals. PARTICIPANTS: The neuropsychological function of 15 older adults with presenting complaints of visual hallucinations who met criteria for Charles Bonnet Syndrome (CBS) were compared with 11 demographically matched controls to determine if there was any evidence of functional brain impairment. CBS patients were screened for focal brain lesions and epileptic disturbance via MRI and EEG and also received pattern visual evoked potentials and ophthalmological examinations. MEASUREMENTS: Scores from the Wechsler Adult Intelligence Scale-Revised, Mattis Dementia Rating Scale, Wechsler Memory Scale, and the Auditory Verbal Learning Test were compared. RESULTS: Significant differences were found between the two groups on the neuropsychological measures. Moreover, 14 of 14 subjects had ocular abnormalities and six of eight had abnormal age-corrected pattern visual evoked potentials indicative of dysfunction in the visual system. CONCLUSIONS: The results of the study indicate that patients diagnosed with Charles Bonnet Syndrome evidence neuropsychological changes commonly associated with the early stages of dementia. Therefore, in patients with impaired vision, the appearance of cognitive deficits, albeit subtle, occur with the onset of visual hallucinations. We propose that isolated visual hallucinations in the older adult may be an indication of the early stages of dementia.

Aged↗
PubMed1995

Effectiveness of apraclonidine and acetazolamide in preventing postoperative intraocular pressure spikes after extracapsular cataract extraction.

We studied the effectiveness of two prophylactic agents in controlling early postoperative intraocular pressure (IOP) increases after cataract surgery. Fifty-four nonglaucomatous patients received either topical 1% apraclonidine, one drop before and after surgery, or sustained-release acetazolamide, 500 mg, or no medication at the completion of planned extracapsular cataract extraction (ECCE). Mean baseline IOPs were similar among patients randomized to the apraclonidine, acetazolamide, and control groups: 15.29 mm Hg, 15.33 mm Hg, and 14.26 mm Hg, respectively. At 3 hours postoperatively, IOPs were significantly lower in the apraclonidine group (11.13 mm Hg, P = .035), nonsignificantly lower in the acetazolamide group (13.3 mm Hg, P = .17), and significantly increased in the control group (21.32 mm Hg, P = .003). One eye in the apraclonidine group and six in the control group had IOPs greater than 30 mm Hg. At 24 hours, the only statistically significant difference was in the control group, whose mean IOPs remained elevated (21.83 mm Hg, P = .0008). One eye in the apraclonidine group, two in the acetazolamide group, and five in the control group had IOPs greater than 30 mm Hg. We found a significant early IOP reduction with apraclonidine given topically preoperatively and at the completion of planned ECCE.

Acetazolamide↗
PubMed1995

Variability in measurement of central retinal artery velocity using color Doppler imaging.

The purpose of our study was to test the reproducibility of the central retinal artery velocity measurements as made by color Doppler imaging and pulsed Doppler spectral tracings and to define the optimal location for placement of the sample volume. We used the Siemens Quantum (Q 2000) with a 7.5 MHz linear array transducer to identify the central retinal artery and record its velocity. Eleven eyes from 11 normal subjects were evaluated for the peak systolic central retinal artery velocity in two positions, the first posteriorly in the optic nerve at an average of 3.56 mm from the surface of the optic disc and the second at an average of 1.76 mm from the surface of the optic disc. We then used a color-flow threshold to identify and record the point of maximal velocity. The range of systolic velocities in the 11 eyes was from 5.85 to 22.51 cm/sec. The peak systolic velocity posteriorly in the optic nerve averaged 8.16 cm/sec, whereas near the surface of the optic disc the velocity averaged 13.89 cm/sec (70.2% higher). Using the color flow threshold method, the maximal velocity was located at an average of 1.98 mm from the surface of the optic disc. Our data show that large differences exist in measured central retinal artery velocity that depend on the location of the measurement, and that color-flow thresholding is valuable in locating the optimal location for pulsed Doppler spectral recording.

Blood Flow Velocity↗
PubMed1995

Retinal tissue oxygen tension in normoxic cats under enflurane anesthesia.

PURPOSE: General anesthesia reduces systemic blood pressure and, thus, ocular perfusion pressure (at constant intraocular pressure). Whether this reduction in ocular perfusion pressure produces retinal hypoxia is unknown. To answer this question, the authors measured inner retinal oxygen tension in cats under general enflurane anesthesia at three clinically relevant levels of anesthesia under normoxic conditions. METHODS: Polarographic oxygen microelectrodes were used to measure inner retinal oxygen tension in cats under enflurane anesthesia at 21% inspired oxygen tension. Measurements were made in the preretinal vitreous body within 100 to 200 microns of the internal limiting membrane of the retina. Three levels of enflurane anesthesia were used: 1.2%, 2.4%, and 3.6%, corresponding to 0.5, 1.0, and 1.5 minimal alveolar concentration. Intraocular pressure of the cats was maintained at a constant normal level throughout the experiments. RESULTS: Under normoxic conditions, inner retinal oxygen tension remained unchanged or increased slightly as ocular perfusion pressure decreased with deeper levels of enflurane anesthesia. CONCLUSION: Commonly used surgical levels of enflurane general anesthesia do not cause hypoxia of the inner retina in cats breathing 21% inspired oxygen. This may be the result of preservation of retinal vascular autoregulation under enflurane anesthesia, retinal vasodilatation secondary to a direct smooth muscle relaxing effect of enflurane, or decreased retinal oxygen use under enflurane anesthesia.

Anesthesia, Inhalation↗
PubMed1994

Photodynamic biologic tissue glue.

We studied both heat- and light-activated tissue glues, and while a heat-activated mixture such as albumin and fluorescein isothiocyanate was effective, we believed that a light-activated substance would have less of an effect on adjacent tissue. Our glue uses a photosensitive singlet oxygen generator to cross-link a protein solder with corneal stromal collagen. The mixture consists of 18% fibrinogen and 2.6 mg/ml of riboflavin-5-phosphate activated with a blue-green (488-514 nm) Argon laser. We tested our glue by soldering 5-mm penetrating central corneal incisions made in human cadaver eyes. The strength of the closure was measured by cannulating the vitreous cavity with an 18-gauge needle connected to a saline reservoir. The pressure in the reservoir was elevated by connecting it to a sphygmomanometer. Immediately following tissue closure, the intraocular pressure was increased until the wound burst. We soldered and measured 10 eyes and found a mean bursting pressure of 154 mm Hg, with a range of 80-260 mm Hg. Our laser-activated tissue glue is an effective adhesive for corneal tissue, and we now plan to carry out toxicity studies in living animals.

Cornea↗
PubMed1992

Corticosteroid treatment for inflammatory bowel disease in pediatric patients increases intraocular pressure.

Intraocular pressure (IOP) was measured in 54 pediatric patients (aged 7-21 years) with inflammatory bowel disease (IBD) who were treated with oral prednisone for 1-104 months. The difference in mean IOP between the treated patients (mean +/- SD, 15.62 +/- 4.11 mm Hg) and 55 age-matched controls (13.83 +/- 2.42 mm Hg) was statistically significant (P = 0.007). The IBD patients were classified as group I, IOP less than or equal to 19 mm Hg in both eyes, and group II, IOP greater than or equal to 20 mm Hg in either eye. Twelve of the 54 patients (22.2%) and none of the controls had IOP greater than or equal to 20 mm Hg (P less than 0.001). Seventeen of the 54 patients (31.5%) were characterized as "steroid responders" (IOP of greater than or equal to 20 mm Hg, change in IOP of greater than or equal to 6 mm Hg between visits, or difference in IOP of greater than or equal to 6 mm Hg between the two eyes). When the dose of prednisone was reduced to 0-10 mg/day 30 days or more before measurement, 9 steroid responders showed a decrease in IOP to within 2 SD of the mean control IOP; 7 of the 9 showed a decrease in IOP of greater than or equal to 6 mm Hg. These observations indicate that while prednisone is a causative factor in increasing the IOP, susceptibility to average doses of prednisone is highly variable, and patients need to be monitored on an individual basis. Because IBD is a chronic disorder that requires prolonged corticosteroid treatment, these children are at risk of developing steroid-induced glaucoma. Careful ophthalmologic monitoring of pediatric IBD patients, as well as of other pediatric patients who receive corticosteroid therapy, is recommended.

Adolescent↗
PubMed1992

Ocular toxicity of prednisone in pediatric patients with inflammatory bowel disease.

We performed ocular examinations on 58 corticosteroid-treated pediatric patients with inflammatory bowel disease (IBD) and on 58 age-matched controls. Posterior subcapsular cataracts (PSC) were detected in 12 of the 58 treated patients (20.7%) and in none of the controls. The difference in mean intraocular pressure (IOP) between the treated patients (15.89 +/- 4.11 mm Hg) and control subjects (13.63 +/- 2.35 mm Hg) was significant statistically (P < 0.001). Twenty-one patients (36.2%) were characterized as "IOP responders" (IOP > or = 20 mm Hg, change in IOP > or = 6 mm Hg between visits, or a difference in IOP > or = 6 mm Hg between the two eyes). Formation of PSC was not correlated significantly (P > 0.05) with the total dose of prednisone, duration of treatment, average daily dose, or number of days on high doses (> or = 25 mg). Raised IOP was correlated (P = 0.005) only with average daily dose (12.4 +/- 10.9 mg/day; range, 0-47 mg/day) 30 days before examination. When the dose of corticosteroid was reduced to < 10 mg/day, 2 patients manifested regression of PSC, and 12 IOP responders showed a decrease in IOP to within 2 SD of the mean control IOP. Only 3 of the 58 treated patients (5.2%) manifested both PSC and raised IOP. A significant inverse correlation (P = 0.02) was established between IOP at first examination and formation of PSC. We propose that the mechanisms for steroid-induced lens opacities and raised IOP do not share the same genetic basis. Because 52% of these children developed either PSC or raised IOP with prednisone therapy, we advocate careful ophthalmologic monitoring of pediatric patients receiving corticosteroids for IBD or any other condition.

Adolescent↗
PubMed1991

A direct correlation of the resolution of pseudophakic cystoid macular edema with acetazolamide therapy.

We report the case of a patient with pseudophakic cystoid macular edema whose visual acuity improved promptly with oral administration of 500 mg of acetazolamide extended-release capsules BID for two weeks. However, vision worsened again within two weeks of discontinuation of the treatment. On resumption of acetazolamide therapy for three weeks, and its slow withdrawal during the following three weeks, the macular edema eventually resolved, and vision returned to normal. Our observation provides a direct correlation of the resolution of pseudophakic cystoid macular edema with acetazolamide therapy and shows the importance of tapering the doses of this regimen.

Acetazolamide↗
PubMed1988

Tissue oxygen uptake from the atmosphere by a new, noninvasive polarographic technique with application to corneal metabolism.

A standard Clark electrode has been modified to continuously monitor the PO2 in a thin, disk shaped reservoir membrane mounted on the electrode membrane surface. In vitro tests were conducted to determine the proportionality constant between the rate of change of reservoir PO2 and the flux of O2 out of the reservoir. The device was then used to determine the corneal O2 uptake on proptosed eyes of previously sacrificed rabbits. Our average measured uptake at 20 degrees C, 1.7 microliter/cm2.hr, agrees with the value 2.3 microliters/cm2.hr calculated from a diffusion analysis of the cornea utilizing literature values of the parameters at 37 degrees C for the three component layers of the cornea when they are adjusted for temperature to 20 degrees C.

Animals↗
PubMed1987

Effect of peripheral cryocoagulation on ocular blood flow.

Using the labeled microsphere impaction technique, we studied the effect of peripheral panretinal transscleral cryocoagulation in pigmented rabbits. One eye of each animal received peripheral cryocoagulation, and the fellow eye of the same animal was used as the control. Thirty-two animals received 40 exposures of peripheral cryocoagulation; twenty-six rabbits received 20 exposures. After 40 exposures of cryocoagulation, choroidal-retinal blood flow was significantly decreased when measured at one to two hours, 24 hours, and two weeks; normal flow recovered by four weeks. After 20 exposures of cryocoagulation, there was a significant reduction in choroidal-retinal blood flow at the earliest measurement time (one to two hours) only. The iris-ciliary body blood flow also was substantially decreased only at the earliest measurement time (one to two hours) and only after 40 exposures.

Animals↗