Assessing the Impact of En Face Retinal Nerve Fiber Layer Imaging on Clinical Decision Making for Glaucoma Suspects.

SIGNIFICANCE: Assessing and managing glaucoma are a complicated process in which experience plays a key role in decision making. Although advanced glaucoma is more easily diagnosed, patients with early glaucoma or who present with suspicious findings are more complicated. A need to aid clinicians in the decision-making process exists. PURPOSE: The purpose of this study was to assess the impact of en face ocular coherence tomography images to clinical decision making when added to standard presentations of circumpapillary retinal nerve fiber layer thickness and automated perimetry. METHODS: Thirty participants from two centers presenting either as a glaucoma suspect or for an initial glaucoma evaluation were enrolled. Six masked investigators were given standard presentations of circumpapillary retinal nerve fiber layer thickness and perimetry. They were asked if glaucomatous damage was present as well as a recommended plan of management on 5-point Likert scales. They were then given en face images of the retinal nerve fiber layer in three different presentations coupled with the standard presentation, and the questions were repeated. An intraclass correlation coefficient (ICC) was generated. RESULTS: The masked investigators had moderate agreement from the standard presentation for assessment (ICC = 0.67 [95% confidence interval {CI}, 0.54 to 0.80] and ICC = 0.69 [95% CI, 0.52 to 0.80], respectively), as well as with the addition of the en face images (ICC = 0.69; 95% CI, 0.56 to 0.81). The en face images tended to change decisions in both assessment and plan toward likely to have glaucoma and likely to start treatment. CONCLUSIONS: The addition of en face images to a standard presentation has an impact on clinical decision making. Although en face images seem to influence the decision toward likely to have glaucoma and likely to treat, it is unclear if this leads to a more accurate decision. Further investigations seem warranted to assess sensitivity and specificity of this approach.

Polarization Variability in Age-related Macular Degeneration.

SIGNIFICANCE: Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss. Complementary imaging techniques can be used to better characterize and quantify pathological changes associated with AMD. By assessing specific light-tissue interactions, polarization-sensitive imaging can be used to detect tissue disruption early in the disease process. PURPOSE: The aim of this study was to compare variability in central macular polarization properties in patients with nonexudative AMD and age-matched control subjects. METHODS: A scanning laser polarimeter (GDx, LDT/CZM) was used to acquire 15 × 15-degree macular images in 10 subjects diagnosed with nonexudative AMD and 10 age-matched control subjects. The coefficient of variation (COV, SD/mean) was used to quantify variability in pixel intensity in the central 3.3° of the macula for custom images emphasizing multiply scattered light (the depolarized light image) and polarization-retaining light (the maximum of the parallel detector image). The intensity COV was compared across subject categories using paired t tests for each image type. RESULTS: The COV in the central macula was significantly higher in the AMD subject group (average, 0.221; 95% confidence interval [CI], 0.157 to 0.265) when compared with matched control subjects (average 0.120; 95% CI, 0.107 to 0.133) in the depolarized light image (P = .01). The COV in the maximum of the parallel detector image was not statistically different between the two subject groups (AMD average, 0.162 [95% CI, 0.138 to 0.185]; control average, 0.137 [95% CI, 0.115 to 0.158]; P = .21). CONCLUSIONS: Variability in multiply scattered light is higher than that of light that is more polarization preserving in patients with nonexudative AMD. Multiple scattering may act as an early indicator representing disruption to the macula in early AMD.

Henle fiber layer phase retardation changes associated with age-related macular degeneration.

PURPOSE: To quantify and compare phase retardation amplitude and regularity associated with the Henle fiber layer (HFL) between nonexudative AMD patients and age-matched controls using scanning laser polarimetry (SLP) imaging. METHODS: A scanning laser polarimeter was used to collect 15 × 15° macular-centered images in 25 patients with nonexudative AMD and 25 age-matched controls. Raw image data were used to compute macular phase retardation maps associated with the HFL. Consecutive, annular regions of interest from 0.5 to 3.0° eccentricity, centered on the fovea, were used to generate intensity profiles from phase retardation data and analyzed with two complementary techniques: a normalized second harmonic frequency (2f) of the fast Fourier Transform (FFT) analysis and a curve fitting analysis using a 2f sine function. Paired t-tests were used to compare the normalized 2f FFT magnitude at each eccentricity between the two groups, the eccentricity that yielded the maximum normalized 2f FFT between paired individuals across the two groups, and curve fitting RMS error at each eccentricity between the two groups. RESULTS: Normalized 2f FFT components were lower in the AMD group at each eccentricity, with no difference between the two groups in the maximum normalized 2f FFT component eccentricity. The root-mean-square (RMS) error from curve fitting was significantly higher in the AMD group. CONCLUSIONS: Phase retardation changes in the central macula indicate loss and/or structural alterations to central cone photoreceptors in nonexudative AMD patients. Scanning laser polarimetry imaging is a noninvasive method for quantifying cone photoreceptor changes associated with central macular disease.

Foveal localization in non-exudative AMD using scanning laser polarimetry.

PURPOSE: To determine whether custom scanning laser polarimetry (SLP) images, differing in polarization content, can be used to accurately localize the fovea in the presence of non-exudative age-related macular degeneration (AMD). To determine whether alterations to the foveal structure in non-exudative AMD significantly disrupts the birefringent Henle fiber layer, responsible for the macular cross pattern in some SLP images. To determine whether phase retardation information, specifically color-coded information representing its magnitude and axis, allow better foveal localization than images including retardation amplitude only. METHODS: SLP images were acquired in 25 AMD subjects and 25 age-matched controls. Raw data were used to generate five custom image types differing in polarization content. The foveal location was marked by three graders in each image type for each subject. The difference in variability was compared between the AMD subjects and matched controls. We further determined whether the orientation of Henle fiber layer phase retardation improved localization in 10 subjects with the highest variability in images including only phase retardation amplitude. RESULTS: Images that differed in polarization content led to strikingly different visualizations of AMD pathology. The Henle fiber layer remained sufficiently intact to assist in fovea localization in all subjects but with more variability in the AMD group. For both the AMD and matched control group, images containing birefringence amplitude and orientation information reduced the amount of intragrader, intergrader, and interimage variability for estimating foveal location. CONCLUSIONS: The disruption in Henle fiber birefringence was evident in the eyes with AMD but nevertheless was sufficient to help in foveal localization despite macular pathology. Phase retardation amplitude and axis of orientation can be a useful tool in foveal localization in patients with AMD.