Optical Coherence Tomography/scanning Laser Ophthalmoscopy Research Articles

Effects of age and gender on macular thickness in healthy subjects using spectral optical coherence tomography/scanning laser ophthalmoscopy.

To examine healthy subjects for normal macular thickness values and determine the effects of gender and age in a Turkish population, using spectral optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO). Six hundred fourteen eyes of 307 subjects with no history of ocular diseases and normal ophthalmic examination were recruited in this cross-sectional, prospective study. The participants were divided into three groups based on age (between 20 and 29years: group 1, between 30 and 39years: group 2, between 40 and 49years: group 3). All subjects were scanned with spectral OCT/SLO, performed by one examiner to acquire the retinal thickness map in the ETDRS grid, and values were recorded for nine sectors, and effects of age and gender were evaluated. When all the subjects were evaluated, the thicknesses were lower in women than men in all sectors (p<0.001). When divided in groups based on age, this difference remained only in the outer segments. However, the differences in outer layers, except outer nasal layer, were thicker in women in group 3 when compared to others in group 3. When compared between groups, only central thickness in group 3 was shown to be higher than group 1 (p=0.06). There was no significant difference of thicknesses in any sector when compared right and left eyes of all subjects. The study reports the variation in retinal thickness between age and gender in a relatively large sample of a Turkish population. It is important to consider these effects while interpreting the OCT images to make an appropriate diagnosis in retinal diseases.

Effect of Aging on Retinal Nerve Fiber Layer Thickness in Normal Asian Indian Eyes: A Longitudinal Study

ABSTRACTPurpose: To determine longitudinal retinal nerve fiber layer (RNFL) thickness measurement change with aging, after a period of 3 years using spectral optical coherence tomography/scanning laser ophthalmoscope (OCT/SLO).Methods: A total of 50 eyes of 25 normal subjects underwent RNFL thickness measurement in 2008 and again in 2011 by a single operator, using spectral OCT/SLO. Measurements were compared at baseline and at follow-up. Linear mixed model analysis was used to measure the effect of age on RNFL thickness measurements over the 3 years.Results: Mean RNFL thickness was 107.92 ± 11.1 µm in 2008 and 106.56 ± 10.8 µm in 2011. For every year increase in age, mean RNFL thickness showed a statistically significant decrease by −0.54 µm (95% confidence interval, −0.76 to −0.31; p < 0.0001). There was a statistically significant loss of peripapillary RNFL thickness in most RNFL regions, except for the temporal quadrant (p = 0.37) and corresponding 7, 8, 9, and 10 o’clock hour sectors (p = 0.72, 0.75, 0.17, 0.14, respectively).Conclusion: RNFL thickness as measured by spectral OCT/SLO decreased significantly with advancing age over a period of 3 years, and was not uniform across the four quadrants. This age-related variation should be taken into account in RNFL thickness measurements when evaluating patients for diagnosis and follow-up of glaucoma.

Establishment of a novel retinoblastoma (Rb) nude mouse model by intravitreal injection of human Rb Y79 cells - comparison of in vivo analysis versus histological follow up.

ABSTRACTRetinoblastoma (Rb) is the most frequent primary intraocular tumour in children and, if left untreated, can cause death. Preclinical animal models that mimic molecular, genetic, and cellular features of cancers are essential for studying cancer and searching for promising diagnosis and treatment modalities. There are several models described for Rb, but none of them fully meet our requirements. The aim of this study was to create a novel xenograft-nude mouse-model with broad application possibilities, which closely resembles the clinical observations of Rb patients and which could be used to investigate the development and spread of the tumour by using scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) as well as histology methods. We injected human retinoblastoma Y79 cells intravitreally in both eyes of immune-deficient nude mice. The incidences of retinoblastoma as well as growth velocity were analysed 3, 6, 9 and 12 weeks after cell injection in vivo by SLO/OCT as well as ex vivo by electron microscopy (EM) and hematoxylin/eosin (HE) staining. Moreover, internal organs were histologically screened for potentially occurring metastases. Three weeks post-injection, animals developed a retinoblastoma, and after five weeks tumour growth resulted in swelling of the eyes in individual animals, showing a similar phenotype to that of untreated Rb patients at advanced stages of tumour-development. After 12 weeks, 67.5% of all analysed eyes (29 of 42) contained a retinoblastoma. At early stages of Rb development, the SLO/OCT analysis correlated with the histology results. If the tumours were too large, only histological investigations were feasible. The ultrastructural characteristics of the xenograft-tumours were very similar to those described for patient's tumours. In one mouse, brain metastases were observed. Our retinoblastoma mouse model closely resembles the human disease. SLO/OCT can be used for the detection of Rb at early stages of development and could be used for monitoring the success of future therapies.

The Photosensitivity of Rhodopsin Bleaching and Light-Induced Increases of Fundus Reflectance in Mice Measured In Vivo With Scanning Laser Ophthalmoscopy.

PurposeTo quantify bleaching-induced changes in fundus reflectance in the mouse retina.MethodsLight reflected from the fundus of albino (Balb/c) and pigmented (C57Bl/6J) mice was measured with a multichannel scanning laser ophthalmoscopy optical coherence tomography (SLO-OCT) optical system. Serial scanning of small retinal regions was used for bleaching rhodopsin and measuring reflectance changes.ResultsSerial scanning generated a saturating reflectance increase centered at 501 nm with a photosensitivity of 1.4 × 10−8 per molecule μm2 in both strains, 2-fold higher than expected were irradiance at the rod outer segment base equal to that at the retinal surface. The action spectrum of the reflectance increase corresponds to the absorption spectrum of mouse rhodopsin in situ. Spectra obtained before and after bleaching were fitted with a model of fundus reflectance, quantifying contributions from loss of rhodopsin absorption with bleaching, absorption by oxygenated hemoglobin (HbO2) in the choroid (Balb/c), and absorption by melanin (C57Bl/6J). Both mouse strains exhibited light-induced broadband reflectance changes explained as bleaching-induced reflectivity increases at photoreceptor inner segment/outer segment (IS/OS) junctions and OS tips.ConclusionsThe elevated photosensitivity of rhodopsin bleaching in vivo is explained by waveguide condensing of light in propagation from rod inner segment (RIS) to rod outer segment (ROS). The similar photosensitivity of rhodopsin in the two strains reveals that little light backscattered from the sclera can enter the ROS. The bleaching-induced increases in reflectance at the IS/OS junctions and OS tips resemble results previously reported in human cones, but are ascribed to rods due to their 30/1 predominance over cones in mice and to the relatively minor amount of cone M-opsin in the regions scanned.

Comparing Macular Thickness Measurements in Patients with Diabetic Macular Edema with the Optos Spectral OCT/SLO and Heidelberg Spectralis HRA + OCT.

The aim of this study was to compare measurements of macular thickness, obtained from patients with diabetic macular edema, using two spectral-domain optical coherence tomography (SD-OCT) devices. These were the Spectralis Heidelberg Retina Angiograph + Optical Coherence Tomography (HRA + OCT) (Heidelberg Engineering), which is often considered the gold-standard for OCT measurement, and the Spectral Optical Coherence Tomography/Scanning Laser Ophthalmoscopy (OCT/SLO) (Optos plc), which can additionally perform microperimetry, a useful measure of visual function. In this prospective observational study, each eye had SD-OCT performed with both devices on the same day by the same investigator. Mean retinal thickness was calculated, and compared between the devices, for central and parafoveal zones within 3 mm of the fovea. 62 eyes were included. In the central, superior, temporal, inferior and nasal zones respectively, mean retinal thickness with Spectralis HRA+OCT was (in microns) 310, 343, 344, 332 and 340; measurements with Spectral OCT/SLO were 237, 298, 297, 289 and 290. Pearson correlations between the devices were 0.752, 0.85, 0.928, 0.839, and 0.823 (p < 0.0001). Although absolute measurements between the devices were significantly different and therefore not interchangeable, the correlation between the devices was over 75% and statistically significant in all zones. Thus, the Spectral OCT/SLO could reliably be used for SD-OCT in patients who may also require microperimetry assessment.

Influence of disc area on retinal nerve fiber layer thickness measurement by spectral domain optical coherence tomography.

Background:To examine the effect of optic disc area on peripapillary RNFLT (retinal nerve fiber layer thickness) measurement at circle diameter of 3.4 mm around optic nerve head using spectral OCT/SLO (Optical coherence tomography/scanning laser ophthalmoscope).Materials and Methods:In this prospective, cross sectional study, one hundred and two eyes of 102 normal subjects underwent RNFLT and disc area measurement using spectral OCT/SLO. Based on disc area, subjects were divided into three groups i.e., <3 mm2 (32 eyes), 3-4 mm2 (36 eyes) and >4 mm2 (34 eyes). The effect of disc area on RNFLT parameters was analyzed using linear regression analysis.Results:The mean and quadrant RNFLT did not show significant correlation with disc area in subjects with disc area of <4 mm2, however in eyes with disc area >4 mm2, average RNFLT, superior and temporal quadrant RNFLT showed negative correlation with disc area, which was statistically significant (P = 0.004, P = 0.005 and P = 0.002, respectively)Conclusion:In healthy eyes of disc area <4 mm2, disc size does not appear to affect peripapillary RNFLT measurement by spectral OCT/SLO. Average, superior and temporal quadrant RNFLT measurements were inversely proportional to disc area in eyes with disc area >4 mm2. Hence, RNFLT measurement by OCT in eyes with optic disc area of >4 mm2 should be interpreted carefully.

Occlusive IOLs for Intractable Diplopia Demonstrate a Novel Near-Infrared Window of Transmission for SLO/OCT Imaging and Clinical Assessment

Occlusive intraocular lens (IOL) implantation is an effective therapeutic option in patients with intractable diplopia, visual confusion, and unsightly leukocoria. However, their use has been restricted by concerns that inability to visualize the retina may prevent the diagnosis of important posterior pole diseases. In this study, transmission spectra of occlusive IOLs were defined as a basis for acquiring scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) images. Fifteen IOLs of three designs were examined: black small and large PMMA and black Lotus (Morcher GmbH, Stuttgart, Germany). Each IOL was placed between a broad-spectrum white light source and a spectroradiometer, to generate transmission spectra for each lens and determine the cutoff wavelength. Transmission in the near-infrared (NIR) range was confirmed with an 850-nm LED. A model eye was implanted with occlusive IOLs, and SLO/OCT scans were acquired with seven clinical SLO/OCT imaging systems. Occlusive IOLs demonstrated high levels of transmission of NIR light. It was determined that most SLO/OCT scanners would achieve 99% to 100% transmission at their operational wavelengths of NIR light. Furthermore, all clinical SLO/OCT imaging systems were capable of imaging fine retinal features without attenuation through occlusive IOLs in a model eye. In this study, a novel NIR window of high-level transmission was identified across the occlusive IOLs with applications to SLO/OCT imaging and NIR-based clinical assessment. The ability to acquire high-quality SLO/OCT scans to detect posterior pole disease may fundamentally change the current view on occlusive IOLs and encourage their use in patients with intractable diplopia.

Optical Coherence Tomography/Scanning Laser Ophthalmoscopy Imaging of Optic Nerve Head Drusen

To evaluate optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO) imaging for optic nerve head drusen (ONHD). Nine consecutive eyes with ONHD were imaged. Each underwent visual field testing, 20-MHz B-scan ultrasonography, photography, and OCT/SLO imaging of the nerve head. Similar evaluation was performed on 12 matched, disease-free control eyes for comparison. OCT/SLO imaging of ONHD demonstrated lucencies (100%), variable amounts of displacement, and thickening of the overlying nerve fiber layer, as well as disorganization of the adjacent retinal pigment epithelium (44%). Optic nerve head topography was measured (using horizontal and vertical electronic calipers). Mean disc diameter was 1.81 mm (range: 1.49 to 2.12 mm). All ONHD demonstrated anterior displacement of the base of the optic nerve cup (shallowing) compared to controls. The cup base was a mean +0.32 mm anterior to the retinal pigment epithelium for ONHD versus -0.23 mm for normal controls. OCT/SLO revealed unique and clinically helpful views of ONHD.

Choroidal Metastases Fundus Autofluorescence Imaging: Correlation to Clinical, OCT, and Fluorescein Angiographic Findings

To correlate fundus autofluorescence (FAF) characteristics of metastatic choroidal tumors with optical coherence tomography/scanning laser ophthalmoscope (OCT/SLO). A retrospective review of 10 choroidal metastases in 9 patients. All tumors were amelanotic, although 8 exhibited surface pigmentation. FAF imaging revealed hyperautofluorescence in areas of focal pigmentation and subretinal fluid with hypoautofluorescent margins (n = 5) corresponding to OCT evidence of retinal pigment epithelial (RPE) thickening and subretinal fluid. Loss of RPE was FAF imaging hypoautofluorescent. FAF images changed with tumor growth. OCT best revealed elevation of the RPE and retina, RPE thickening and folds, and retinal detachment. FAF imaging best defined surface characteristics and tumor margins. FAF imaging hyperautofluorescence correlated to focal hyperpigmentation, subretinal fluid, and advancing tumor edges. OCT better demonstrated intraretinal findings (atrophy, subretinal fluid, and increased and lost RPE). This study shows that FAF imaging and OCT reveal unique tumor characteristics of choroidal metastasis.

Vitreoschisis in macular diseases

ObjectivesVitreoschisis is a possible pathogenic mechanism in macular diseases. Thus, the vitreoretinal interface was evaluated in monkey eyes and patients with various macular diseases in search of vitreoschisis. It is...

Reproducibility of OCT/SLO Measurements in Healthy Eyes

To determine the reproducibility of optical coherence tomography/scanning laser ophthalmoscope (OCT/SLO) measurements within and between observers and within and between sessions in healthy eyes. Forty eyes of 40 healthy volunteers recruited from the outpatient service of the Department of Ophthalmology at the University Hospital of Alexandroupolis, Greece, were included. Retinal thickness scans were performed 3 times by two experienced operators within each of 3 sessions, which took place within a month, using the spectral OCT/SLO. The OCT/SLO provides retinal nerve fiber layer (RNFL) thickness and volume measurements and a 3D tomography analysis of optic nerve head. Statistical analysis was conducted using Bland-Altman plots, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). As shown by the CoV values, RNFL parameters were generally found to have high reproducibility (CoV ranging from 4.3% to 10.9% for both operators), whereas optic disc parameters had scores reaching up to 22.5%. On the other hand, as shown by the ICC values, intraobserver and interobserver reproducibility for the OCT/SLO was high for optic disc parameters but low for RNFL thickness and volume measurements. Interobserver reproducibility was found to be highest for the maximum cup depth parameter and lowest for the superior volume. Bland-Altman plots indicate that bias is minimal for practically all parameters and scatterplot homoscedasticity is high. According to our data, SLO/OCT generally has a good reproducibility profile, as differences between the two operators were small. However, additional studies on the reproducibility of measurements with the OCT/SLO are needed.

Long‐term study of vascular perfusion effects following arteriovenous sheathotomy for branch retinal vein occlusion

To evaluate the perfusion effects and long-term visual outcome of pars plana vitrectomy (PPV) combined with arteriovenous sheathotomy (AVS) with or without triamcinolone for nonischaemic branch retinal vein occlusion (NI-BRVO). Prospective, interventional case series of eight patients with NI-BRVO and haemorrhagic macular oedema. Patients underwent PPV and AVS (n = 5), or PPV, AVS and intravitreal triamcinolone (IVT, n = 3). A masked grading technique assessed fundus photographs and fluorescein angiography (FFA) following surgery. Scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) evaluated macular oedema and outer retinal architecture. Main outcomes examined included visual acuity (VA), retinal reperfusion, collateral vessel regression, vascular dilatation, cystoid macular oedema (CMO), and ocular neovascularization. Seven of eight patients underwent uncomplicated surgery, with increased intraretinal perfusion and reduced engorgement of distal retinal veins. The mean pre-logMAR VA was 0.8 (SD 0.17) and did not improve significantly after surgery (post-logMAR 0.6, SD 0.38; p = 0.11, paired t-test). SLO/OCT showed persistent CMO in four patients, and subfoveal thinning of the photoreceptor layer. Collateral vessels disappeared at the blockage site post-AVS in 7/8 eyes, and this was associated with improved retinal perfusion. Six of eight patients developed epiretinal membrane. No patients developed ocular neovascularization. The average follow-up was 34.5 months. PPV with AVS is a safe procedure, and adjunctive IVT had no additional effects on vascular perfusion. Successful decompressive surgery was followed by disappearance of collateral vessels at the BRVO blockage site and was a clinical marker for intravascular reperfusion. Long-term epiretinal gliosis and subfoveal photoreceptor atrophy limited functional and visual recovery.

VITREO-PAPILLARY ADHESION IN MACULAR HOLE AND MACULAR PUCKER

Vitreo-macular pathology may be influenced by vitreo-papillary adhesion (VPA). Optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO) was used to identify VPA in full-thickness macular hole, lamellar hole, and macular pucker (MP). Ultrasonography and OCT/SLO were performed in 55 subjects: 16 with macular hole, 11 with lamellar hole, and 28 with MP. The main outcome measures were the presence of posterior vitreous detachment by ultrasound, and the findings of VPA and intraretinal cysts by OCT/SLO. Posterior vitreous detachment was detected by ultrasound in 26/28 (92.9%) eyes with MP, 6/11 (54.5%) eyes with lamellar hole (P < 0.05), and 4/16 (25%) eyes with macular hole (P < 0.00001). Optical coherence tomography/scanning laser ophthalmoscopy detected VPA in 14/16 (87.5%) macular hole eyes, 4/11 (36.4%) lamellar hole eyes (P < 0.05), and 5/28 (17.9%) MP eyes (P < 0.00005). Intraretinal cysts were present in 4/5 (80%) MP eyes with VPA but only 1/23 (4.3%) MP eyes without VPA (P < 0.005). Vitreo-papillary adhesion was significantly more common in full-thickness macular hole than lamellar hole or MP. When present in MP, VPA was frequently associated with intraretinal cysts. Hence, VPA may have an important influence on the vectors of force at the vitreo-retinal interface inducing holes and cysts.

USE OF CORONAL SIMULTANEOUS OPTICAL COHERENCE TOMOGRAPHY/SCANNING LASER OPHTHALMOSCOPY TO DEMONSTRATE CYSTOID MACULAR EDEMA SECONDARY TO EXTRAFOVEAL RETINAL HOLE

To describe a clinical appearance of macular edema secondary to extrafoveal retinal hole using coronal (en-face) optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO) imaging. Case report. A 76-year-old man developed an extrafoveal retinal hole in his right eye after pars plana vitrectomy and epiretinal membrane removal 1 year after surgery. He complained of decreased central vision. Coronal scan showed extrafoveal retinal hole with multiple retinal cysts surrounding the retinal hole and communicating with the macular area. The OCT/SLO ophthalmoscope can be useful in understanding pathophysiology of macular edema.

Anti–Vascular Endothelial Growth Factor Bevacizumab (Avastin) for Radiation Retinopathy

To evaluate intravitreal bevacizumab for radiation retinopathy. After plaque radiation therapy, 6 patients developed radiation retinopathy (retinal edema, hemorrhages, microangiopathy, and neovascularization). Intravitreal bevacizumab (1.25 mg in 0.05 mL) was periodically injected (every 6-8 weeks). Ophthalmic evaluations included visual acuity, ophthalmic examination, fundus photography, fluorescein angiography, and optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO) imaging. No bevacizumab-related ocular or systemic adverse effects have occurred within the first 8 months of therapy. Progressive reductions in retinal hemorrhages, exudates, cotton-wool spots, and microangiopathy were documented by photography, angiography, and OCT/SLO imaging. Decreased macular edema was the most common finding. Improvement or stabilization of visual acuity was noted in all cases. Intravitreal bevacizumab was tolerated, improved or maintained vision, and reduced hemorrhage and retinal edema (angiographic leakage). This study should lead to additional and longer-term studies of humanized monoclonal anti-vascular endothelial growth factor antibody therapy for radiation retinopathy.

Anti-VEGF Bevacizumab (Avastin®) for Radiation Optic Neuropathy

To evaluate intravitreal bevacizumab treatment for radiation optic neuropathy (RON). Interventional case report. At The New York Eye Cancer Center, a patient symptomatic of decreased vision because of RON was treated with intravitreal bevacizumab (1.25 mg). Main outcome measures included visual acuity, appearance of the optic nerve, fundus photography, angiography, and optical coherence tomography/scanning laser ophthalmoscopy (OCT/SLO). Within one week, her vision improved from 20/32 to 20/20 with a reduction in optic disk hemorrhage. At six weeks, evidence of both decreased hemorrhage and optic disk edema was documented by photography, angiography, and OCT/SLO. At the three and five-month follow-up visits, the hemorrhages resolved, and her disk margins were sharp. There were no ocular or systemic side effects. Intravitreal bevacizumab was tolerated, improved vision, and reduced hemorrhage as well as optic disk edema (angiographic leakage). Anti-VEGF therapy (e.g. bevacizumab) should be investigated for both ocular and nonocular radiation neuropathy.