Comparison between B-Scan and En Face Images for Incomplete and Complete Retinal Pigment Epithelium and Outer Retinal Atrophy

PURPOSE

To evaluate and compare the detection of incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) and complete retinal pigment epithelium and outer retinal atrophy (cRORA) assessed on OCT B-scans versus persistent choroidal hypertransmission defects (hyperTDs) assessed by en face choroidal OCT images.

DESIGN

Retrospective, cross-sectional study.

PARTICIPANTS

Patients with late atrophic age-related macular degeneration imaged on the same day using both Spectralis OCT and Cirrus OCT.

MAIN OUTCOME MEASURE

Agreement between the B-scan and en face OCT for the detection of hyperTDs, cRORA, and iRORA.

METHODS

Two independent graders examined en face OCT and structural OCT to determine the presence and location of hyperTDs, iRORA, and cRORA.

RESULTS

A total of 239 iRORA and cRORA lesions were detected on the B-scans, and 249 hyperTD lesions were identified on the en face OCT images. There was no significant difference (P = 0.88) in the number of lesions. There was no significant difference in the 134 cRORA lesions identified on B-scans and the 131 hyperTDs detected on en face OCT images (P = 0.13). A total of 105 iRORA lesions were identified by B-scan assessment; however, 50 of these iRORA lesions met the criteria for persistent hyperTDs on en face OCT images (P < 0.001). When considering the topographic correspondence between B-scan and en face OCT detected lesions, the mean percentage of agreement between B-scan detection of cRORA lesions with en face OCT detection was 97.6 % (P = 0.13).

CONCLUSIONS

We observed high overall agreement between cRORA lesions identified on B-scans and persistent hyperTDs identified on en face OCT. However, en face imaging was able to detect iRORA lesions that had a greatest linear dimension ≥ 250 μm in a nonhorizontal en face dimension.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Novel En Face OCT-Based Closure Patterns in Idiopathic Macular Holes

PURPOSE

To determine the postoperative en face OCT pattern of closure in idiopathic macular holes (MHs).

DESIGN

Retrospective, multicentric, observational study.

PARTICIPANTS

Patients aged > 18 years with a diagnosis of idiopathic MH, with well documented en face OCT images.

METHODS

Baseline characteristics and preoperative OCT and en face OCT parameters like horizontal and vertical minimum linear diameter (MLD), horizontal and vertical basal hole diameter (BHD), hole height, acircularity index, and hole orientation were measured.

MAIN OUTCOME MEASURE

The type of hole closure on en face OCT, and a comparison of baseline parameters and final visual acuity among the en face closure types.

RESULTS

A total of 64 eyes of 62 patients (24 men and 40 women) with a mean age of 63.8 ± 12.4 years. The median duration of symptoms was 3 months (interquartile range, 1.75-10.5). The eyes had a mean baseline visual acuity of 0.97 ± 0.46 logarithm of minimum angle of resolution (logMAR). The baseline horizontal MLD was 591.7 ± 219.4 μm and the vertical MLD was 552.9 ± 198.2 μm. Baseline horizontal and vertical BHD were 1240.3 ± 521.1 μm and 1142.1 ± 478.1 μm, respectively. The mean hole height was 394.8 ± 123.2 μm. Two different patterns were noted on en face OCT: round, or linear. A total of 38 eyes had a round/centripetal closure and 26 eyes had a linear closure (17 eyes had a horizontal closure, 7 eyes had an oblique closure, while 2 eyes had a vertical closure). The mean final visual acuity was 0.80 ± 0.43 logMAR (Snellen equivalent of 20/125). Eyes with linear closure (0.76 ± 0.23 logMAR) had a significantly (P = 0.03) better visual acuity than the round closure group (1.07 ± 0.28 logMAR), only in eyes with horizontal MLD of > 650 μm, but not when other MLD cut-offs were used.

CONCLUSION

We describe 2 different patterns of hole closure (linear and round) on en face OCT. Further studies will be required to determine its functional significance.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Evaluation of Plaque Burden and Lipid Content in Atherosclerotic Plaques

Atherosclerosis is a chronic inflammatory disease characterized by the formation of lipid-rich, fibrous plaques within the arterial wall of medium and large arteries. Plaques prone to rupture are typically rich in lipids and pro-inflammatory markers. Cells within the plaque can take up lipids via different mechanisms leading to the formation and accumulation of lipid-rich foam cells, a key hallmark of the disease. Evaluation of plaque burden and lipid content is hence important to determine disease progression and severity. This chapter describes the most commonly used staining methods that enable visualization and analysis of mouse atherosclerotic plaques. These methods include en face preparation of mouse aorta, and staining sections of arteries using hematoxylin and eosin, Oil Red O, and Masson's Trichrome.

En face optical coherence tomography transillumination for evaluation of retinal pigment epithelium alteration in central serous chorioretinopathy: correlation with multimodal imaging

PURPOSE

To study optical coherence tomography (OCT) en face imaging approach to evaluate retinal pigment epithelium (RPE) alteration in central serous chorioretinopathy (CSC).

METHODS

Forty eyes with CSC were imaged with structural en face OCT, fluorescein angiography (FA), and fundus autofluorescence (FAF). Structural en face OCT projections were generated using a 200-µm slab with the inner limit at the outer choroid to register choroidal hypertransmission signal in transillumination manner. Two masked graders independently defined the area of RPE alteration on resultant images. Agreement between graders and correlation between imaging modalities was assessed by kappa coefficients (k) and intraclass correlation coefficients (ICC), respectively.

RESULTS

The measurements derived from three methods were highly correlated with ICC of 0.99 (95% CI 0.99 to 1.0) for OCT and FA, 0.97 (95% CI 0.93 to 0.99) for OCT and FAF, and 0.98 (95% CI 0.95 to 0.99) for FA and FAF. For the measurement of the area of RPE alteration, kappa value for inter-grader agreement was 0.94 for OCT, 0.89 for FA, and 0.92 for FAF.

CONCLUSION

En face OCT proved a reliable tool for the noninvasive evaluation of RPE status in CSC.

[Acute macular neuroretinopathy: En face OCT description, case series]

Acute macular neuroretinopathy (AMN) is a rare disease characterized by involvement of the outer retinal layers of the macula. The diagnosis of AMN is based on multimodal imaging, combining infrared reflectance (IR) imaging and optical coherence tomography with B-scan analysis (OCT-B). The en face OCT is a tomographic image processing technique, integrating data from entire A-scans to create a frontal retinal image of the desired area. Structural en face OCT imaging appears to be effective in delineating AMN lesions, using segmentation between the outer plexiform line and the ellipsoid line. In the future, analysis of the various modalities of a single OCT acquisition may be sufficient to diagnose AMN.

Characteristics and treatment responses of cystoid retina associated with central serous chorioretinopathy

PURPOSE

To detect the characteristics of cystoid retina associated with central serous chorioretinopathy (CSC) using multimodal imaging and to evaluate anatomical and functional responses for treatment.

STUDY DESIGN

A retrospective case series METHOD: This retrospective study included 21 eyes of 17 patients with the treatment for combined cystoid retinal changes and submacular fluid associated with CSC. Multimodal imaging analysis including cross-sectional OCT, en face OCT, fluorescein and indocyanine green angiography, and fundus autofluorescence were performed to assess the characteristics of cystoid changes. In 21 eyes of 17 patients, clinical courses after treatment were reviewed.

RESULTS

Fourteen of 17 patients were men (82.4%), and the mean age was 63.2. Fluorescein angiography revealed one or more focal leakages in all eyes, and intense leakage, due to peripapillary atrophy and from areas showing retinal pigment epithelial atrophy, was observed in 11 eyes and 12 eyes respectively. En face OCT visualized cystoid retinal changes as honey-comb like areas, and this was observed in the papillomacular region in 16 eyes (76.2%). After reduced-fluence photodynamic therapy (PDT), combination of anti-VEGF and PDT, or photocoagulation, subretinal fluid resolved in 20 eyes (95.2%), and complete resolution of cystoid retinal changes was obtained in 13 eyes (61.9%).

CONCLUSION

Cystoid retinal changes can be associated with patchy retinal pigment epithelial atrophy and with peripapillary atrophy in CSC eyes. Laser treatment is beneficial for resolving cystoid retina as well as subretinal fluid.

Posterior Vitreous Structures Evaluated by Swept-source Optical Coherence Tomography with En Face Imaging

PURPOSE

To evaluate posterior vitreous structures using swept-source (SS) optical coherence tomography (OCT) with en face imaging.

METHODS

We retrospectively reviewed OCT images of healthy individuals who did not have intra-ocular disease. We obtained high-definition horizontal and vertical line scans crossing the fovea and 3D scans using SS-OCT, with the 3D scan centered between the fovea and the optic-nerve head. An enhanced vitreous visualization function was used to highlight vitreous structures. En face mode was used to measure the area of Martegiani (AM) and bursa premacularis (BP). We performed all measurements using a built-in function of the viewing software.

RESULTS

We enrolled 24 eyes from 12 healthy individuals. The mean patient age was 28.7 ± 4.6 years (range, 24 to 39 years). The mean AM and BP areas were 5.73 ± 0.88 and 18.76 ± 6.95 mm², respectively. In en face imaging, AM shape was most frequently a vertical oval (18 / 22, 81.8%), while the predominant BP shape was round (16 / 20, 80.0%). AM was in contact with the optic disc, either at the temporal-disc margin (13 eyes, 59.1%) or the nasal optic-disc margin (9 eyes, 40.9%).

CONCLUSIONS

Posterior vitreous structures, such as AM and BP, were readily visualized using en face imaging with SS-OCT. Investigating normal vitreous configuration might help in understanding changes in vitreous structures associated with retinal pathology.

Using frozen section margin control technique to manage non-melanomatous skin lesions in high-risk sites

BACKGROUND

In the UK, non-melanoma skin cancers (NMSCs) that are incompletely excised, recurrent or in sites high risk for incomplete excision are often offered Mohs micrographic surgery (MMS). Variations in waiting times and geographical access to MMS affect patient preference for other treatments. Our unit offers excision of such lesions under complete margin frozen section histological examination.

METHODS

All NMSCs excised at our unit by complete margin frozen section histological analysis from 2010 to 2014 were retrospectively reviewed. The number of excisions required, complete excision rates and recurrences to date were analysed.

RESULTS

Sixty-nine patients were treated using this technique with a total of 70 lesions excised. Approximately 71% of the excision margins were clear after primary excision, 27% at second excision and 1% at third excision. Patients had a mean follow-up of 12 months (range: 1-48) with no patients lost to follow-up and no recurrences reported to date. Ninety-eight percent of NMSC cases were completely excised and two cases were incompletely excised.

CONCLUSION

We have found the rates of excision and recurrence of the high-risk NMSCs excised at our unit to be comparable to those reported with MMS. In addition, our data show that around 29% of patients would have had incomplete margins on primary resection, thus justifying the use of this technique in this group. We suggest that this technique is a safe and useful alternative to MMS in areas where waiting times or geographical patient preference may prohibit its use.

RPE Cell and Sheet Properties in Normal and Diseased Eyes

Previous studies of human retinal pigment epithelium (RPE) morphology found spatial differences in density: a high density of cells in the macula, decreasing peripherally. Because the RPE sheet is not perfectly regular, we anticipate that there will be differences between conditions and when and where damage is most likely to begin. The purpose of this study is to establish relationships among RPE morphometrics in age, cell location, and disease of normal human and AMD eyes that highlight irregularities reflecting damage. Cadaveric eyes from 11 normal and 3 age-related macular degeneration (AMD) human donors ranging from 29 to 82 years of age were used. Borders of RPE cells were identified with phalloidin. RPE segmentation and analysis were conducted with CellProfiler. Exploration of spatial point patterns was conducted using the "spatstat" package of R. In the normal human eye, with increasing age, cell size increased, and cells lost their regular hexagonal shape. Cell density was higher in the macula versus periphery. AMD resulted in greater variability in size and shape of the RPE cell. Spatial point analysis revealed an ordered distribution of cells in normal and high spatial disorder in AMD eyes. Morphometrics of the RPE cell readily discriminate among young vs. old and normal vs. diseased in the human eye. The normal RPE sheet is organized in a regular array of cells, but AMD exhibited strong spatial irregularity. These findings reflect on the robust recovery of the RPE sheet after wounding and the circumstances under which it cannot recover.

Investigating the choriocapillaris and choroidal vasculature with new optical coherence tomography technologies

The body of knowledge of in vivo investigation of the choroid has been markedly enhanced by recent technological advances in optical coherence tomography (OCT). New insights elucidating the morphological features of the choriocapillaris and choroidal vasculature, in both physiological and pathological conditions, indicate that the choroid plays a pivotal role in many posterior segment diseases. In this article, a review of the histological characteristics of the choroid, which must be considered for the proper interpretation of in vivo imaging, is followed by a comprehensive discussion of fundamental principles of the current state-of-the-art in OCT, including cross-sectional OCT, en face OCT, and OCT angiography using both spectral domain OCT and swept source OCT technologies. A detailed review of the tomographic features of the choroid in the normal eye is followed by relevant findings in prevalent chorioretinal diseases, focusing on major causes of vision loss such as typical early and advanced age-related macular degeneration, polypoidal choroidal vasculopathy, central serous chorioretinopathy, pachychoroid spectrum disorders, diabetic choroidopathy, and myopia.

Scanning laser 'en face' retinal imaging of epiretinal membranes

PURPOSE

Comparison of scanning laser ophthalmoscopy (SLO) based 'en face' imaging techniques of patients with epiretinal membranes (ERM) and evaluation of the accuracy of preoperative diagnostic imaging.

METHODS

A consecutive, prospective series of 53 study eyes of 46 patients with clinically diagnosed and in optical coherence tomography (OCT) confirmed symptomatic ERMs were included in this study. Spectral domain (SD-) OCT volume scans (20° × 20° with 49 horizontal sections, ART 15) including SLO en face and fundus autofluorescence (FAF) images of the macula were obtained with HRA2 (Heidelberg Retina Angiograph-Optical Coherence Tomography, Heidelberg Engineering, Heidelberg, Germany). In addition, wide-field SLO color and FAF images (Optomap 200Tx, Optos PLC, Dunfermline, UK) were performed also covering the macular area. En face images of both devices were graded for each included study eye based on SD-OCT cross sectional scans.

RESULTS

Grading of SD-OCT (HRA2) based SLO en face green-blue enhanced multi-color, green reflectance, blue reflectance and standard multi-color visualization revealed a better detectability of ERM than SD-OCT-based en face infrared or FAF images or wide-field SLO (Optomap) based pseudo-color, red laser separation, green laser separation, or FAF images. Both FAF visualizations, HRA2 and Optomap based, achieved low mean scores. SD-OCT based en face thickness map visualization revealed good visualization but poor demarcation of epiretinal membranes.

CONCLUSIONS

In summary, en face regular or enhanced multicolor SLO images acquired with HRA2 allow a better visualization of epiretinal membranes for preoperative evaluation compared to SD-OCT based en face thickness map or pseudo-color images acquired with Optomap while infrared or FAF images are least suitable to depict epiretinal membranes.

A reliable frozen section technique for basal cell carcinomas of the head and neck

Basal cell carcinomas (BCCs) of the head and neck treated by conventional techniques of surgical excision, curettage, cryotherapy and radiation therapy have recurrence rates of up to 42%. Mohs micrographic surgery (MMS) decreases the recurrence rate but can be expensive, delay definitive reconstruction and is limited in its availability. The authors report a series of 50 patients with head and neck BCCs treated by a surgeon-directed 'en face' frozen section technique that immediately evaluates the entire peripheral and deep margins during BCC resection, and potentially offers a more efficient and equally effective alternative to MMS. Patient demographics, pathology results, operative time, technique and outcomes are all reported. With a mean follow-up of three years, there was only one recurrence (1.7%). Mean total operative time was 1 h 47 min. The authors conclude that this surgeon-directed 'en face' frozen section technique does not require any specialized training, enables more rapid and reliable results than standard frozen section techniques that are currently used, and provides outcomes equivalent to MMS in the surgical treatment of head and neck BCCs.