Foveal cone loss in tamoxifen maculopathy: a case report.

BACKGROUND: Tamoxifen is used in low dose concentrations (20-40 mg per day) as a therapy for breast cancer but is known to have ocular side effects. In this case report, the foveal cone integrity in a tamoxifen-treated patient who complained of a small central scotoma in the left eye while reading was examined using high resolution adaptive optics imaging. CASE PRESENTATION: Both eyes of a 54-year-old Caucasian, non-hispanic female who had been treated with tamoxifen for 1.5 years were examined using various imaging modalities including fundus photography, fundus autofluorescence, fluorescein angiography, spectral-domain optical coherence tomography, and adaptive optics scanning laser ophthalmoscopy. Clinical spectral-domain optical coherence tomography showed a very small disruption to the photoreceptor layer at the fovea in the left eye only. However, adaptive optics scanning laser ophthalmoscopy imaging revealed foveal cone loss in both eyes, but to a lesser extent in the right eye. Inner retinal changes were not observed in either eye. CONCLUSION: The area of cone loss was similar in size to a single newsprint letter when projected onto the retina, matching the patient's description of a scotoma in the left eye. Given the isolated loss of foveal cone photoreceptors with the absence of previously reported inner retinal and vascular changes, our results may indicate the earliest retinal changes associated with tamoxifen retinopathy.

High Resolution Imaging of the Outer Retina in Type 2 Acute Macular Neuroretinopathy.

PURPOSE: To investigate the outer retinal changes in a patient with type 2 acute macular neuroretinopathy (AMN). METHODS: A 35-year-old Caucasian female complaining of a unilateral blind spot was imaged using various retinal imaging modalities including clinical optical coherence tomography (OCT), OCT-angiography, fundus fluorescein angiography and adaptive optics (AO). RESULTS: Fundus examination revealed multiple paracentral reddish-brown petaloid lesions in the symptomatic left eye, while the other eye was unremarkable. Clinical OCT showed areas of hyper-reflectance at the outer plexiform layer / outer nuclear layer complex with a disrupted inner /outer segment junction, which are characteristic features of type 2 AMN. AO imaging further revealed either shortening or absence of cone outer segments within the AMN lesions attributing to the darker features observed in the enface images from fundus photography and scanning laser ophthalmoscopy. CONCLUSION: The AO findings indicate that the petaloid lesions in type 2 AMN are caused by a combination of the shortening and absence of the outer segment in individual cone photoreceptors.

CONE PHOTORECEPTOR INTEGRITY ASSESSED WITH ADAPTIVE OPTICS IMAGING AFTER LASER POINTER-INDUCED RETINAL INJURY.

PURPOSE: To examine the three-dimensional foveal cone photoreceptor structure in a patient who had suffered laser pointer-induced retinal injury. METHODS: Patient underwent standard fundus photography and clinical spectral domain optical coherence tomography imaging. High-resolution imaging was performed using an adaptive optics-optical coherence tomography-scanning laser ophthalmoscope. RESULTS: Adaptive optics imaging revealed loss of inner and outer segments of cone photoreceptors whereas the anterior retinal layers appeared healthy. Analysis of cone topology showed an increase in Voronoi domain area and a less regular hexagonal packing structure closer to the lesion site. CONCLUSION: Exposure to laser pointer radiation, however brief, can result in damage to the retina. Here, repeated imaging nine months later showed a decrease in the size of the lesions (ranging from 3.7 to 23.9%) compared with the first time point. However, the longer-term prognosis is likely permanent scarring.

Structural Integrity of Individual Cone Photoreceptors After Short-Wavelength Subthreshold Micropulse Laser Therapy for Diabetic Macular Edema.

BACKGROUND AND OBJECTIVE: Subthreshold micropulse laser (SML) treatment at 577 nm has been proposed as a safe and efficacious therapy for diabetic macular edema (DME). The study objective was to evaluate the integrity of individual cone photoreceptors after SML treatment using high-resolution retinal imaging. PATIENTS AND METHODS: An observational cohort study of four subjects with DME treated using SML was followed over time. Cone inner and outer segment lengths and total retinal thicknesses (TRT) were measured as the edema resolved. The primary outcome was the detection of any laser-induced photoreceptor damage / change following the SML treatment using adaptive optics imaging. RESULTS: Individual cones observed pre-treatment remained visible, whereas cones that were initially obscured by the DME became more discernable after the treatment. TRT showed statistically significant thinning in half of the subjects. One subject showed no significant change, whereas another showed a statistically significant increase in TRT despite the treatment. No subject was found to have photoreceptor damage following treatment. CONCLUSIONS: SML at 577 nm did not result in measurable structural damage to the underlying photoreceptor layer, supporting previous work that SML is a safe alternative for treating DME. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:946-954.].

Inner Retinal Changes in Primary Open-Angle Glaucoma Revealed Through Adaptive Optics-Optical Coherence Tomography.

PURPOSE: To examine the microstructural changes in the inner nuclear layer (INL) and ganglion cell layer (GCL) in a primary open-angle glaucoma (POAG) subject at 2 timepoints, 4 months apart. PATIENTS AND METHODS: This case-control study (1 POAG subject and 1 normal control) used the single cell, 3-dimensional volumetric imaging capability of an adaptive optics-optical coherence tomography-scanning laser ophthalmoscopy system to examine the inner retina. RESULTS: At the area of greatest glaucomatous change in the POAG subject [3-degrees temporal (T), 3-degrees inferior (I), right eye], the GCL was greatly thinned at both timepoints, yet retinal ganglion cell soma remained visible amid a meshwork of capillaries. Microcystic lesions in the INL were visible at both timepoints, ranging in diameter from 8 to 43 µm on day 1 to 11 to 64 µm at 4 months, with an average diameter increase of ∼124%. Small hyperreflective features (not seen in the contralateral eye or control subject) at a depth midway through the INL seemed correlated to the development of microcysts. CONCLUSIONS: We demonstrate the ability to image microcystic lesions early in their development and have quantified longitudinal changes. The presence of small hyperreflective structures at a layer midway through the INL seems to be a precursor to their formation and is a potential biomarker for assessing POAG severity and progression. The adaptive optics imaging system is also able to visualize retinal ganglion cells in this subject, despite severe thinning of the GCL.

Volumetric imaging of rod and cone photoreceptor structure with a combined adaptive optics-optical coherence tomography-scanning laser ophthalmoscope.

We have designed and implemented a dual-mode adaptive optics (AO) imaging system that combines spectral domain optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) for in vivo imaging of the human retina. The system simultaneously acquires SLO frames and OCT B-scans at 60 Hz with an OCT volume acquisition time of 4.2 s. Transverse eye motion measured from the SLO is used to register the OCT B-scans to generate three-dimensional (3-D) volumes. Key optical design considerations include: minimizing system aberrations through the use of off-axis relay telescopes, conjugate pupil plane requirements, and the use of dichroic beam splitters to separate and recombine the OCT and SLO beams around the nonshared horizontal scanning mirrors. To demonstrate system performance, AO-OCT-SLO images and measurements are taken from three normal human subjects ranging in retinal eccentricity from the fovea out to 15-deg temporal and 20-deg superior. Also presented are en face OCT projections generated from the registered 3-D volumes. The ability to acquire high-resolution 3-D images of the human retina in the midperiphery and beyond has clinical importance in diseases, such as retinitis pigmentosa and cone-rod dystrophy.

A dynamic light scattering approach for monitoring dental composite curing kinetics.

OBJECTIVES: The purpose of this study was to develop and evaluate a dynamic light scattering-based method for monitoring the polymerization reaction of a light activated dental composite. METHODS: Laser light back-scattered from thin disk-shaped composite samples was used to study the curing reaction kinetics. Samples were irradiated simultaneously on opposite surfaces with a 633 nm laser beam and a halogen curing lamp (320, 160, or 100 mW/cm(2)). Dynamic laser speckle patterns were imaged onto a CCD camera at a rate of 32 frames/s for 2 min. The intensity decorrelation rate calculated from sequential speckle patterns was used to assess the rate of motion within the samples during the reaction. RESULTS: Motion within the composite increased immediately upon the onset of light exposure for all trials. This was followed by a brief period characterized by a relatively constant high rate of motion. Finally the rate of motion decreased exponentially. The reaction acceleration, deceleration, and maximum rate were dependent upon the irradiance of the curing light source. SIGNIFICANCE: This method monitors reaction rate and the change in reaction rate at high temporal resolution without contact. Reaction kinetics was shown to begin immediately after light exposure suggesting limited opportunity for viscous flow and stress relief.

Detrimental effects of speckle-pixel size matching in laser speckle contrast imaging.

Through a series of simulations and experiments, we demonstrate that the frequently cited criterion of matching speckle size to detector element (pixel) size in laser speckle contrast imaging (LSCI) has the detrimental effect of reducing the contrast and thereby decreasing the variation in the laser speckle contrast image. Unlike quasi-elastic light scattering, where this matching condition has been shown to maximize the signal-to-noise ratio, in LSCI, the minimum speckle size must exceed the Nyquist criterion in order to maximize the contrast of the speckle patterns.