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Biomedical subjects

A C Ho

Publications and source records attributed to A C Ho.

At least 19 recordsLinked to original sources
PubMed2001

Laser burn intensity and the risk for choroidal neovascularization in the CNVPT Fellow Eye Study.

OBJECTIVE: To explore the relationship between laser burn intensity and the subsequent risk for development of choroidal neovascularization (CNV) in eyes assigned to the treatment group of the Fellow Eye Study (FES) of the Choroidal Neovascularization Prevention Trial (CNVPT), using computerized methods for laser burn quantitation, and to examine the association between laser burn intensity and (1) drusen reduction and (2) visual acuity. METHODS: Color fundus images before and immediately after laser treatment in the CNVPT FES were available for 53 of 59 eyes. Prelaser and postlaser treatment images were analyzed using custom-developed computer software, allowing for laser burn identification and quantitation. As measures of laser burn intensity, we derived integrated burn rating (IBR) (the integral of the normalized intensity difference divided by the burn pixels), and the maximum burn intensity (MAX). We identified CNV using fluorescein angiography. A Cox proportional hazards model was fit to the time to development of CNV. Baseline and 6-month color photographs were used to determine reduction in drusen. Visual acuity was measured using a standardized protocol. RESULTS: The IBR and MAX spanned 4.5 logarithm units. After adjusting for smoking history and predominant drusen size, the risk ratio for CNV per logarithm unit of increasing laser burn intensity for each measure was 2.0 (P =.05) for MAX and 1.7 (P =.07) for IBR. When patients were divided into high- and low-intensity treatment groups of equal size, the high-intensity group had more drusen reduction (57% vs 32%; P =.14). There was no effect of laser intensity on change in visual acuity at 6 months. CONCLUSION: Higher-intensity prophylactic laser applications appear to be associated with a greater risk for development of CNV and with more extensive drusen reduction.

Choroidal Neovascularization↗
PubMed2001

The intubating laryngeal mask airway in severe ankylosing spondylitis.

PURPOSE: To evaluate the use of inhalational induction followed by intubation through the intubating laryngeal mask (ILM) for patients with severe ankylosing spondylitis undergoing elective surgery who prefer airway management under anesthesia. METHODS: Nine patients undergoing a total of 11 procedures were enrolled in the study. Fentanyl 2 microg*kg(-1), midazolam 0.035 mg*kg(-1) and sevoflurane in oxygen 100% were used for induction. The ILM was inserted when the end-tidal sevoflurane concentration reached 3%. After an effective airway was established, atracurium 0.5 mg*kg(-1) was given. A polyvinyl chloride tube in the reversed position using a blind technique was used to intubate the trachea. RESULTS: The ILM provided an effective airway on 11/11 occasions at the first attempt. Intubation was successful at the first attempt on 7/11 occasions, at the second attempt on 2/11 and at the third attempt in 1/11. Intubation failed in one patient. The mean (range) minimal oxygen saturation was 99.4% (97-100%). There were no problems with ILM removal. CONCLUSION: Inhalational induction followed by ILM insertion and blind intubation is a reasonable option in patients with severe ankylosing spondylitis undergoing elective surgery who prefer airway management under anesthesia.

Adult↗
PubMed2001

Patient-initiated second medical opinions: their necessity and economic cost.

PURPOSE: To assess the value of patient-initiated second medical opinions (SMO). METHODS: The authors prospectively collected demographic data from 100 consecutive patients. The authors recorded major changes in the patients' care, such as inappropriate surgery recommended, inadequate treatment performed, and appropriate treatment not recommended. The authors also recorded costs incurred or saved by the patients and the third-party payers. RESULTS: In nearly 15 of the cases, the authors had major disagreements with the initial diagnosis or management. Surgery had been recommended in 28 cases. They advised against it in nine. In 72 cases, no surgery had been recommended. They advised and performed it in five. The management of five other patients was not in accordance with that recommended by large clinical trials or was inadequately done. Including the consultation fees, surgery performed or advised against, retinal angiography, and ultrasonography, the 100 SMO cost third-party payers $12,426. If the authors subtract the cost of noncontroversial surgery they recommended and if the patients had paid the consultation fee and had brought along their fluorescein angiograms, third-party payers would have saved $4,079. CONCLUSION: The savings SMO generated by eliminating unnecessary surgery resulted in improved patient care at minimal cost to third-party payers.

Adolescent↗
PubMed2001

Photodynamic therapy update.

Photodynamic therapy uses a photoactivating agent to selectively treat choroidal neovascularization. In April 2000, the United States Food and Drug Administration approved verteporfin photodynamic therapy for the treatment of subfoveal, predominately classic, choroidal neovascularization caused by age-related macular degeneration. The treatment of choroidal neovascularization from other causes such as myopia, angioid streaks, and idiopathy, and presumed ocular histoplasmosis syndrome is still under investigation. Other photoactivating agents are being evaluated. Photodynamic therapy has been shown to halt the progression of visual loss in patients with age-related macular degeneration who have subfoveal predominately classic choroidal neovascularization. The socio-economic impact of verteporfin approval has yet to be determined.

Choroidal Neovascularization↗
PubMed2001

Diagnosis of progressive compression of the aortic true lumen with intraoperative transesophageal echocardiography during repair of dissection of thoracic aorta--a case report.

We report an incident of progressive compression of the true lumen of aorta which happened immediately after cardiopulmonary bypass (CPB) and was diagnosed with intraoperative transesophageal echocardiography (TEE) in a patient undergoing an emergent repair of type A aortic dissection under femoral perfusion. During the CPB period, intraoperative TEE revealed gradual expansion of the false lumen which nearly obstructed the true lumen of the dissected aorta. The possible mechanism was related with distension of the false lumen by a dominant flow from retrograde femoral perfusion of CPB. With the application of intraoperative TEE, we could easily detect the hemodynamic changes of thoracic aorta and find the real causes so as to solve the perfusion abnormalities.

Adult↗
PubMed2000

The intubating LMA: a comparison of insertion techniques with conventional tracheal tubes.

PURPOSE: To compare the performance of the intubating laryngeal mask airway (ILMA) in assisting blind tracheal intubation with conventional tracheal tubes of different curvatures and the frequency of possible associated complications. METHODS: After informed consent, 240 ASA I-II adults undergoing elective surgery participated in a randomized, single blind clinical trial to receive blind trachea intubation via ILMA with a conventional tracheal tube curved with normal (Normal group) or reversed (Reverse group) direction. More than three attempts at intubation was regarded as failure. The lowest oxygen saturation during intubation was recorded and postintubation sore throat and hoarseness were evaluated with verbal analog scales. RESULTS: The overall success rates of intubation with Normal and Reverse groups were not different (96.7% and 94.2% respectively). Successful intubation at the first attempt was higher in the Reverse group than in the Normal group (86.7% vs 75.0%, P=0.033). The incidence of sore throat was higher in the Normal group than in the Reverse group (19.2% vs 9.2% respectively, P =0.042). CONCLUSIONS: Blind trachea intubation via an ILMA with the conventional curved tracheal tube is feasible and highly successful. Reverse curve direction is preferable at the first attempt of intubation for its higher success rate and lower incidence of complications.

Adolescent↗
PubMed2000

One-year outcomes of panretinal photocoagulation in proliferative diabetic retinopathy.

PURPOSE: To describe the clinical features and complications of diabetic retinopathy, visual acuity, and number of repeat treatments after panretinal photocoagulation for proliferative diabetic retinopathy in a tertiary care center. METHODS: A cohort study was conducted with data collection from medical records of patients undergoing panretinal photocoagulation between 1985 and 1995 at the Scheie Eye Institute; 297 eyes of 186 patients were eligible for study. RESULTS: The presence of neovascularization of the disk at baseline, an earlier onset of diabetes, and a shorter duration of disease before panretinal photocoagulation were the strongest risk factors for needing an additional panretinal photocoagulation treatment. Sixty-two percent of eyes with poor visual acuity (< or =20/200) at baseline still had poor visual acuity at 1 year, and 76% with good visual acuity (> or =20/40) at baseline maintained good visual acuity at 1 year. Poor vision at baseline was the only risk factor for having poor vision at 1 year. Vitreous hemorrhage was present in 44% of eyes at baseline. New vitreous hemorrhage developed in 37% of eyes during the first year after panretinal photocoagulation. A traction retinal detachment was present in 4% of eyes at baseline and newly developed in 6% of eyes during follow-up. A repeat panretinal photocoagulation treatment was performed in 39% of eyes after initial treatment. A vitrectomy was performed in 10% of eyes from baseline through the 1-year follow-up visit. CONCLUSIONS: The data from this study are useful for counseling patients with respect to likely visual outcome, possibility of major complications from proliferative diabetic retinopathy, and the chance of undergoing additional laser treatment after panretinal photocoagulation.

Adolescent↗
PubMed2000

Unusual immunogammopathy maculopathy.

PURPOSE: To describe an unusual maculopathy in patients with serum immunogammopathies. DESIGN: Retrospective observational small case series. PARTICIPANTS: Three patients derived from the clinical retina practices of the authors were noted to have unusual maculopathy. METHODS: Each patient underwent fluorescein angiography and serum laboratory evaluation. MAIN OUTCOME MEASURE: Findings on fluorescein angiography. RESULTS: An unusual and atypical macular detachment with or without subretinal precipitates or fundus signs of serum hyperviscosity, such as retinal hemorrhages and dilated retinal veins, may be observed in patients with immunogammopathies such as multiple myeloma, Waldenström's macroglobulinemia, and benign polyclonal gammopathy. Fluorescein angiography shows macular hypofluorescence with no evidence of retinal vascular or retinal pigment epithelial leakage within the macular elevation. CONCLUSIONS: Patients with atypical unilateral or bilateral macular detachment may be afflicted with a serum immunogammopathy such as multiple myeloma or Waldenström's macroglobulinemia. Diagnostic serum protein electrophoresis and hematology consultation should be considered.

Aged↗
PubMed2000

Psychophysical evidence for rod vulnerability in age-related macular degeneration.

PURPOSE: To determine whether there is rod system dysfunction in the central retina of patients with age-related macular degeneration (AMD). METHODS: Dark-adapted sensitivity (500-nm stimulus) and light-adapted sensitivity (600 nm) were measured psychophysically at 52 loci in the central 38 degrees (diameter) of retina in 80 patients with AMD, and results were compared with those from older adult normal controls. All dark-adapted data were corrected for preretinal absorption. RESULTS: Mean field dark-adapted sensitivity was significantly lower in AMD patients as a group than in normal subjects. Within the AMD group were subsets of patients with normal mean dark- and light-adapted sensitivities; reduced dark-adapted sensitivities without detectable light-adapted losses; both types of losses; and, least commonly, only light-adapted losses. Regional retinal analyses of the dark-adapted deficit indicated the greatest severity was 2 degrees to 4 degrees or approximately 1 mm from the fovea, and the deficit decreased with increasing eccentricity. CONCLUSIONS: These psychophysical results are consistent with histopathologic findings of a selective vulnerability for parafoveal rod photoreceptors in AMD. The different patterns of rod and cone system losses among patients at similar clinical stages reinforces the notion that AMD is a group of disorders with underlying heterogeneity of mechanism of visual loss. Dark-adapted macula-wide testing may be a useful complement to the more traditional outcome measures of fundus pathology and foveal cone-based psychophysics in future AMD trials.

Aged↗
PubMed1999

The use of multiplane transesophageal echocardiography to evaluate residual patent ductus arteriosus during video-assisted thoracoscopy in adults.

BACKGROUND: Video-assisted thoracoscopic surgery (VATS) has emerged as an innovative and popular procedure for interruption of patent ductus arteriosus (PDA), while intraoperative transesophageal echocardiography (TEE) has proven to be an effective monitor in the evaluation of residual patency. Previous reports on the adequacy of surgical interruption of PDA under VATS and TEE are available for pediatric patients, but only limited information is available for adults with PDA. MATEIALS AND METHODS: Between August 1995 and October 1997, we monitored 35 adult patients undergoing PDA interruption via VATS with Hewlett-Packard color Doppler multiplane TEE throughout the procedure. The average PDA diameter was 10.2 +/- 1.8 mm. All the PDA were completely ligated. RESULTS: Thirty-two patients showed no ductal flow after double ligation. In the other three patients, residual flow was detected intraoperatively after double ligation, but it was quickly abolished by the third ligation. One patient showed faint ductal flow by transthoracic echocardiography at postoperative follow-up, but no reintervention was needed. CONCLUSIONS: Our study showed that, with the refinement of adult PDA interruption via VATS, intraoperative multiplane TEE provides higher resolution for direct evaluation of the entire course of PDA ligation without interrupting the surgical procedure and minimizes the incidence of complications.

Adult↗
PubMed1999

Macular fibrosis associated with talc retinopathy.

PURPOSE: To investigate a patient with talc retinopathy who developed macular fibrosis with resultant visual loss. METHODS: A 64-year-old intravenous drug abuser was evaluated for bilateral peripheral retinal neovascularization. He admitted to abusing oral methylphenidate intravenously. Funduscopy showed numerous intravascular talc particles in the macular area of both eyes. Over a period of next 4 years, visually significant macular fibrosis gradually developed in both eyes, the left eye more than the right eye. RESULTS: Fluorescein angiography confirmed the presence of bilateral peripheral retinal neovascularization with adjacent areas of ischemic retina. The patient was treated with peripheral laser treatment to the ischemic retina with resultant regression of peripheral retinal neovascularization. Bilateral macular fibrosis accounted for the reduced vision in our patient. CONCLUSION: Talc retinopathy can be associated with macular fibrosis with resultant visual loss.

Fibrosis↗
PubMed1999

Laser-induced drusen reduction improves visual function at 1 year. Choroidal Neovascularization Prevention Trial Research Group.

OBJECTIVE: To describe the relationship of laser-induced drusen reduction to change in visual function at 1 year among patients enrolled in the Choroidal Neovascularization Prevention Trial (CNVPT). DESIGN: Comparison of groups with and without drusen reduction; follow-up of a randomized controlled trial. PARTICIPANTS: Evaluations of drusen and visual acuity at baseline and at 1 year were performed for 351 eyes of the 432 eyes enrolled in the CNVPT Bilateral Drusen Study and Fellow Eye Study (81%). One hundred eighty-four eyes were assigned to observation, and 167 eyes were assigned to laser treatment. Eyes with conditions that precluded an analysis of drusen reduction, such as those that developed choroidal neovascularization (CNV) within the first year, are excluded from this analysis. METHODS: Change in macular drusen between initial visit and after 1 year was assessed by side-by-side grading by evaluators masked to information on visual function. Visual acuity, contrast threshold, and critical print size were measured by certified visual function examiners. MAIN OUTCOME MEASURES: Change in visual acuity is the primary outcome. Change in contrast threshold and change in critical print size are secondary outcome measures. RESULTS: Laser-treated eyes with 50% or more drusen reduction at 1 year had more 1- and 2-line increases in visual acuity and less losses in visual acuity compared with laser-treated eyes with less drusen reduction or with observed eyes (P = 0.001). Similar improvements were noted for contrast threshold but not critical print size at 1 year. CONCLUSIONS: Laser-induced drusen reduction is associated with improved visual acuity and contrast sensitivity in eyes at 1 year. Longer term effects of laser-induced drusen reduction on visual function require additional observation. The overall potential value of laser treatment in eyes with high-risk drusen requires consideration of not only short-term effects on vision but also the effects of CNV and atrophy on vision.

Aged↗
PubMed1999

Laser treatment in eyes with drusen.

During the past several decades, many individuals have noted that drusen may resolve after macular laser photocoagulation. The lack of effective therapies against choroidal neovascularization (CNV) due to age-related macular degeneration (AMD) has prompted many invesigators to explore strategies designed to prevent CNV in eyes with high-risk drusen. Currently, several pilot studies in the United States, Spain, Sweden, Australia, and the United Kingdom are in progress; the Choroidal Neovascularization Prevention Trial (CNVPT) is the largest pilot study to date and is detailed herein. A definitive study, the Complications of Age-Related Macular Degeneration Prevention Trial, aims to evaluate the effects of laser treatment in patients with bilateral drusen and will commence this year.

Choroidal Neovascularization↗