Improved repeatability of retinal thickness measurements using line-scan ophthalmoscope image-based retinal tracking.

BACKGROUND AND OBJECTIVE: To assess repeatability and speed of a line-scan ophthalmoscope (LSO) image-based tracking system and compare to the point-scanning approach. PATIENTS AND METHODS: Thirty-five eyes with retinal diseases underwent volume scans using two spectral-domain optical coherence tomography (OCT) devices: a line-scan tracking Cirrus HD-OCT (Carl Zeiss Meditec; Dublin, CA) and point-scan tracking Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). Eyes were also imaged on the Cirrus HD-OCT with tracking disabled. RESULTS: Mean difference in central subfield thickness (CST) between consecutive scans was 2.6 µm for the Cirrus without tracking, 1.7 µm with tracking, and 3.6 µm for the Spectralis. The repeatability standard deviation was 3.0 µm for the Cirrus without tracking, 1.5 µm with tracking, and 4.0 µm for the Spectralis. Coefficient of variation for the CST was 1.1% for the Cirrus without tracking, 0.5% with tracking, and 1.4% for the Spectralis. Mean scan acquisition time was 12.3 ± 6.2 seconds for the Spectralis, 7.8 ± 6.7 for the Cirrus with tracking, and 4.3 ± 0.6 for the Cirrus without tracking. CONCLUSION: Real-time LSO image-based retinal tracking appears to improve repeatability of OCT retinal thickness measurements.

High-resolution OCT: an innovative tool for posterior segment imaging.

Optimal management of posterior segment disorders requires a high-resolution and preferably noninvasive imaging tool for better definition of diseases. High-resolution optical coherence tomography can provide noninvasive, high-definition imaging of the posterior segment, allowing earlier diagnosis, better follow-up of chronic cases, and more accurate and timely monitoring of the effect of therapeutic agents. Recent findings suggest an individualized approach to vitreoretinal and choroidal diseases is possible based not only on traditional ophthalmic investigations, but also on high-resolution optical coherence tomography. This innovative tool has the combined advantages of high speed, high resolution, and safe use.

Measurement of subfoveal choroidal thickness using spectral domain optical coherence tomography.

BACKGROUND AND OBJECTIVE: To compare subfoveal choroidal thickness (SFCT) in normal patients and those with known ocular pathology using spectral domain optical coherence tomography (SD-OCT). PATIENTS AND METHODS: This retrospective, observational case series was conducted at a tertiary care center where 194 consecutive eyes from 102 patients were imaged. Patients were not included or excluded based on presence or absence of pathology. One masked observer imaged the choroid and a second masked observer measured SFCT. Multivariate analysis was used and a statistical model created to analyze the changes in SFCT induced by age, diabetic retinopathy, glaucoma, wet and dry age-related macular degeneration, and other posterior pole pathology. RESULTS: The mean SFCT of the 194 eyes studied was 246.59 ± 93.17 µm with a mean age of 55.50 ± 19.70 years. A strong negative relationship was found between age and SFCT (R(2) = 0.42), with an average 3.09-µm decrease in SFCT per additional year of age. Subgroup analysis demonstrated that patients with diabetic retinopathy, wet or dry age-related macular degeneration, and glaucoma all had SFCT measurements that were statistically significantly less than those of normal patients. However, when regression analysis was used to control for age, this difference was no longer significant. CONCLUSION: No differences were found in SFCT in patients with glaucoma, macular degeneration, or diabetic retinopathy compared to eyes lacking pathology when age was counted as a confounding variable. Age has a strong inverse relationship with SFCT, independently confirming prior studies and creating a foundation for more research on the relationship between ocular pathology and choroidal thickness.