Biomedical subjects

Sunita Radhakrishnan

Publications and source records attributed to Sunita Radhakrishnan.

6 recordsLinked to original sources

PubMed2006

Detection of primary angle closure using anterior segment optical coherence tomography in Asian eyes.

OBJECTIVE: To evaluate noncontact anterior segment optical coherence technology (AS-OCT) as a qualitative method of imaging the anterior chamber angle and to determine its ability to detect primary angle closure when compared with gonioscopy in Asian subjects. DESIGN: Prospective observational case series. PARTICIPANTS: Two hundred three subjects were recruited from glaucoma clinics in Singapore with diagnoses of primary angle closure, primary open-angle glaucoma, ocular hypertension, or cataract. Both eyes (if eligible) of each patient were included in the study. Exclusion criteria were pseudophakia or previous glaucoma surgery. METHODS: Images of the nasal, temporal, and inferior angles were obtained with AS-OCT in dark and then light conditions. Gonioscopic angle width was graded using the Spaeth classification for each quadrant in low lighting conditions. MAIN OUTCOME MEASURES: Angle closure was defined by AS-OCT as contact between the peripheral iris and angle wall anterior to the scleral spur and by gonioscopy as a Spaeth grade of 0 degree (posterior trabecular meshwork not visible). Comparison of the 2 methods in detecting angle closure was done by eye and by individual. Sensitivities and specificities of AS-OCT were calculated using gonioscopy as the reference standard. RESULTS: Complete data were available for 342 eyes of 200 patients. Of the patients, 70.9% had a clinical diagnosis of treated or untreated primary angle closure. Angle closure in > or =1 quadrants was detected by AS-OCT in 142 (71%) patients (228 [66.7%] eyes) and by gonioscopy in 99 (49.5%) patients (152 [44.4%] eyes). The inferior angle was closed more frequently than the nasal or temporal quadrants using both AS-OCT and gonioscopy. When performed under dark conditions, AS-OCT identified 98% of those subjects found to have angle closure on gonioscopy (95% confidence interval [CI], 92.2-99.6) and led to the characterization of 44.6% of those found to have open angles on gonioscopy to have angle closure as well. With gonioscopy as the reference standard, specificity of AS-OCT in the dark was 55.4% (95% CI, 45.2-65.2) for detecting individuals with angle closure. CONCLUSION: Anterior segment OCT is a rapid noncontact method of imaging angle structures. It is highly sensitive in detecting angle closure when compared with gonioscopy. More persons are found to have closed angles with AS-OCT than with gonioscopy.

Adult↗

PubMed2006

Bilateral macular lesions in a 10-year-old girl.

PURPOSE: To report a previously undescribed macular dystrophy. DESIGN: Single descriptive case report. METHODS: Presentation of clinical findings, including ophthalmoscopy, fluorescein angiography, full-field and multifocal electroretinography (ERG), optical coherence tomography (OCT), and visual fields. RESULTS: A 10 year-old Caucasian girl had peculiar reddish blotchy macular lesions bilaterally, associated with decreased visual acuity, and no family history of similar lesions. Fluorescein angiography was inconclusive and showed mottled hyperfluorescence in the macula. The full-field electroretinogram was normal, but multifocal ERG revealed diminished waveforms centrally. CONCLUSION: This is possibly a new macular dystrophy, the nature of which remains to be determined.

Child↗

PubMed2005

Comparison of optical coherence tomography and ultrasound biomicroscopy for detection of narrow anterior chamber angles.

OBJECTIVE: To assess the accuracy of classification of narrow anterior chamber (AC) angles using quantitative imaging by optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM). DESIGN: Observational comparative study. METHODS: A high-speed (4000 axial scans/s) anterior segment OCT prototype was developed using a 1.3-microm light source. Seventeen normal subjects (17 eyes) and 7 subjects (14 eyes) with narrow angle glaucoma were enrolled. All subjects underwent gonioscopy, OCT, and UBM. Quantitative AC angle parameters (angle opening distance, angle recess area, and the trabecular-iris space area [a new parameter we have defined]) were measured from OCT and UBM images using proprietary processing software. MAIN OUTCOME MEASURES: Specificity and sensitivity in identifying narrow angles with image-derived AC angle parameters. RESULTS: Eight of 31 eyes were classified as having narrow angles (Shaffer grade < or =1 in all quadrants). The AC angle parameters measured by both OCT and UBM had similar mean values, reproducibility, and sensitivity-specificity profiles. Both OCT and UBM showed excellent performance in identifying eyes with narrow angles. Areas under the receiver operating characteristic curves for these parameters were all in the range of 0.96 to 0.98. CONCLUSIONS: Optical coherence tomography was similar to UBM in quantitative AC angle measurement and detection of narrow angles. In addition, it was easier to use and did not require contact with the eye. Optical coherence tomography is a promising method for screening individuals at risk for narrow angle glaucoma.

Adult↗

PubMed2005

Optic Nerve Sheath Meningiomas.

Optic nerve sheath meningiomas (ONSMs) grow slowly and, if untreated, patients may have stable visual function for up to several years. Treatment of an ONSM may lead to vision loss (radiation retinopathy or optic neuropathy). Therefore, observation is recommended for a patient with ONSM and relatively preserved visual acuity, color vision, pupils, and visual fields. Follow-up every 4 to 6 months initially is recommended extending to annual examinations if visual function and tumor size remain stable for a few years. Neuroimaging can be repeated every 12 months. An undisputed decline in visual function or any intracranial extension warrants treatment of the ONSM. The treatment of choice for a tumor confined to the orbit is stereotactic fractionated radiation. Stereotactic fractionated radiation uses multiple small doses of radiation using tight margins. A reasonable alternative, three-dimensional conformal fractionated radiation uses computed tomography-guided planning but usually requires wider margins. Conventional radiation uses much wider margins and would not be recommended for treatment of ONSM. The radiation can be administered during 5 to 6 weeks in 28 daily fractions of 1.8 to 2 Gy/fraction to a total of 50.4 to 56 Gy. Many patients have improvement or stabilization of their visual function. Gamma knife radiosurgery does not have a role in ONSM because the required dose is toxic to the optic nerve. A tumor that extends intracranially may be treated with fractionated radiation if any vision remains. Surgical excision can be considered for significant intracranial extension but this often leads to complete vision loss in the ipsilateral eye. A blind, disfigured eye also may be treated with en bloc surgical resection of the meningioma.

Journal Article↗

PubMed2005

Optical coherence tomography imaging of the anterior chamber angle.

Primary angle closure glaucoma is a common cause of visual loss worldwide. Gonioscopy and other current methods of assessment of the anatomy of the anterior segment relevant to the diagnosis of this disease, such as ultrasound biomicroscopy, have significant limitations. Anterior segment optical coherence tomography, with its rapid, noncontact, and high-resolution image acquisition, seems to be a promising tool for the evaluation of the anterior chamber angle configuration, including changes induced by illumination and laser peripheral iridotomy. It has the potential for use as a rapid screening tool for detection of occludable angles. Ongoing clinical studies should help to evaluate its efficacy in this regard.

Anterior Chamber↗

PubMed2004

Optical coherence tomography of the anterior segment of the eye.

Optical coherence tomography is a versatile tool for visualization and measurement of corneal and anterior segment anatomy. Keratorefractive surgery, anterior chamber biometry, and angle assessment are some of the applications that should benefit from this technology.

Anterior Eye Segment↗