THE IMPORTANCE OF THE PERIPHERAL RETINA IN PATIENTS WITH CENTRAL SEROUS CHORIORETINOPATHY

Lattice Degeneration Imaging with Optical Coherence Tomography Angiography

Purpose

To describe a series of cases of lattice degeneration of the retina imaged with optical coherence tomography angiography (OCTA).

Methods

Four eyes of four patients were included and evaluated with green reflectance using a confocal scanning laser ophthalmoscopy and OCTA. In each case, the microcirculation of the retina and choriocapillaris within the lesion, as well as choroidal thickness beneath the lesion, were assessed.

Results

OCTA showed regional loss of retinal perfusion and rarefication of the choriocapillaris network within the lesion and the presence of venous collectors in the choroid beneath the lesion. The choroid was substantially thinner beneath the lesion compared to the adjacent normal region. Cross-sectional OCT scans showed retinal thinning, vitreal adhesion, atrophic holes, and subretinal fluid within the lesions.

Conclusion

Lattice degeneration is characterized by significant local changes in retinal and choroidal microcirculation which may play an important role in the pathophysiology of lattice degeneration.

Application of Deep Learning Methods for Binarization of the Choroid in Optical Coherence Tomography Images

Purpose

The purpose of this study was to develop a deep learning model for automatic binarization of the choroidal tissue, separating choroidal blood vessels from nonvascular stromal tissue, in optical coherence tomography (OCT) images from healthy young subjects.

Methods

OCT images from an observational longitudinal study of 100 children were used for training, validation, and testing of 5 fully semantic networks, which provided a binarized output of the choroid. These outputs were compared with ground truth images, generated from a local binarization technique after manually optimizing the analysis window size for each individual image. The performance was evaluated using accuracy and repeatability metrics. The methods were also compared with a fixed window size local binarization technique, which has been commonly used previously.

Results

The tested deep learning methods provided a good performance in terms of accuracy and repeatability. With the U-Net and SegNet networks showing >96% accuracy. All methods displayed a high level of repeatability relative to the ground truth. For analysis of the choroidal vascularity index (a commonly used metric derived from the binarized image), SegNet showed the closest agreement with the ground truth and high repeatability. The fixed window size showed a reduced accuracy compared to other methods.

Conclusions

Fully semantic networks such as U-Net and SegNet displayed excellent performance for the binarization task. These methods provide a useful approach for clinical and research applications of deep learning tools for the binarization of the choroid in OCT images.

Translational Relevance

Deep learning models provide a novel, robust solution to automatically binarize the choroidal tissue in OCT images.

Wide-field choroidal thickness and vascularity index in myopes and emmetropes

PURPOSE

To study regional variations in choroidal thickness (CT), luminal thickness and stromal thickness of the choroid, and choroidal vascularity index (CVI) in low myopic and emmetropic eyes using wide-field optical coherence tomography (OCT).

METHODS

Sixty-nine healthy young adults between 20 and 38 years of age participated in this study, including 40 low myopes (mean ± SD spherical equivalent (MSE) refractive error: -3.00 ± 1.39 D, range: -6.00 to -0.62 D) and 29 emmetropes (MSE: -0.05 ± 0.09 D, range: -0.25 to +0.12 D). Wide-field CT, luminal thickness, stromal thickness and CVI were measured across five eccentricities (fovea, parafovea, perifovea; near-periphery and periphery) and four quadrants (nasal, temporal, inferior and superior), in vertical and horizontal meridians, while controlling for a range of extraneous factors potentially influencing the CT. Custom-written software was used to segment and binarize the OCT images.

RESULTS

Wide-field CT, luminal thickness and stromal thickness, averaged across all participants, exhibited significant topographical variation, with the foveal (379 ± 8 µm, 200 ± 4 µm, 179 ± 4 µm, respectively) and peripheral (275 ± 8 µm, 161 ± 4 µm, 114 ± 4 µm, respectively) regions presenting the thickest and thinnest regions (all p < 0.001). Wide-field CVI showed a progressively higher percentage (greater vascularity) with increasing eccentricity from the fovea towards the periphery (p < 0.001). Macular CT and stromal choroidal thickness were significantly thinner in myopes compared to emmetropes (p < 0.05). Myopes (55.7 ± 0.3%) showed a slightly higher CVI compared with emmetropes (54.4 ± 0.4%) (p < 0.05).

CONCLUSIONS

Low myopia in young adults was associated with significant choroidal thinning across the macular, but not extramacular regions, with this decrease in choroidal thickness mostly attributed to thinning in the stromal component of the choroid, rather than the luminal (vascular) component.

Peripheral retinal avascularity and capillary leakage in central serous chorioretinopathy

Purpose

To report a novel finding of peripheral retinal avascularity (PRA) and peripheral capillary leakage (PCL) on wide-field fluorescein angiography (WFA) in non-dependent quadrants, in eyes with bilateral chronic central serous chorioretinopathy (CSCR).

Methods

Forty six patients with bilateral CSCR were studied. Four patients had PRA and PCL, and 42 patients did not. The demographic profile, clinical findings, and imaging characteristics of the two groups were compared.

Results

There was no significant difference between those patients with and without PRA and PCL with respect to the demographic profile, clinical findings, and imaging characteristics. Laser photocoagulation to extrafoveal points of leakage seen on fluorescein angiography (FA) was sufficient to cause complete resolution of CSCR in these 4 patients. PRA areas were not treated.

Conclusion

The PRA and PCL in CSCR are novel findings, which have not been previously described.

Peripheral retinal findings in populations with macular disease are similar to healthy eyes

PURPOSE

Recent evidence suggests several macular diseases are associated with peripheral retinal changes. This study investigated the number, type and management consequences of peripheral retinal findings detected in patients attending a referral only, eye-care clinic, the Centre for Eye Health(CFEH) with macular disease.

METHODS

Records of 537 patients attending CFEH for a macular assessment were included in the study. Subjects were classified as having age-related macular degeneration (AMD), epiretinal membrane (ERM), central serous chorioretinopathy (CSCR), inherited macular dystrophy or no macular disease. Data extracted included reason for referral, macular findings, peripheral findings (based on examination by ultra-widefield scanning laser ophthalmoscopy), diagnosis and management.

RESULTS

After age-matching, the number of peripheral findings in subjects with AMD, ERM or CSCR was not significant different to normal subjects. The most common finding for all cohorts were non-specific, degenerative changes such as drusen or pigmentation (61-72%) except inherited macular dystrophy subjects who had mostly vascular findings (30%; p < 0.05). Subjects with AMD and ERM with peripheral findings were significantly more likely to be reviewed or referred to an ophthalmologist than discharged back to their community eye care provider compared to subjects without findings. However only 8% of subjects had altered management based specifically on peripheral findings suggesting the macular findings in most subjects dictated their management. For those with a change, it was significant (upgrade to referral to an ophthalmologist). Peripheral findings also flagged 5% of subjects with vascular findings for referral to their general practitioner (GP).

CONCLUSIONS

Overall, the percentage and distribution of peripheral retinal findings in some macular diseases was similar to normal subjects. However, subjects with peripheral findings appeared to have significant differences in management. Considering some common findings, such as peripheral drusen may be relevant to AMD pathogenesis and therefore affect management of this disease, assessment of the peripheral retina should not be overlooked when the clinical focus is on the posterior pole.

Wide-field choroidal thickness profile in healthy eyes

The introduction of wide field optical coherence tomography (WF-OCT) has provided newer insights in the imaging of peripheral choroid. We evaluated choroidal thickness (CT) and large choroidal vessel thickness (LCVT) of 20 eyes in horizontal and vertical meridians using WF-OCT. A high-definition line scan through the fovea in both horizontal and vertical meridian was captured in primary and extremes of gaze to obtain scans up to mid-equator. CT and LCVT measurements were done across predefined points in macular area and all quadrants. LCVT was calculated after identifying a large choroidal vessel near choroidoscleral interface. The main outcome measures were differences in CT and LCVT in macular and four quadrants. Mean CT (331.23 ± 76.34 µ) and LCVT (201.46 ± 54.31 µ) in vertical macular segment were significantly more than CT (245.79 ± 55.38 µ; p = 0.0002) and LCVT (150.48 ± 52.58 µ; p = 0.004) in horizontal macular segment. CT at peripheral points in all quadrants was significantly reduced as compared to subfoveal CT (all p values < 0.05) with maximum reduction in inferior quadrant (64.5%). Using linear regression, only quadrant had a significant effect on CT and LCVT (both p < 0.001). CT and LCVT are highest at the macular area with reduction towards the periphery. The contribution of LCVT to CT is less at the fovea compared to other peripheral points.

Retinal microvasculature alteration in central serous chorioretinopathy

The aim of the present study was to investigate the changes of retinal microvascular network in patients with central serous chorioretinopathy (CSCR). A total of fifteen patients (right eye) with CSCR and 15 normal controls (right eye) were recruited. We used optical coherence tomography angiography to scan 6×6 mm macular retinal blood flow images with the application of a series of customized image segmentation processing program software to obtain microvascular and macrovascular density, and compared the superficial microvascular (SMIR), superficial macrovascular ring (SMAR) and the superficial total microvascular (STMI) density between CSCR patients and control group. Using the annular partition (C1-C6) and quadrant partition methods on the macular, we compared the retinal vessel density changes. We also performed ROC analysis of superficial retinal microvessel density in CSCR retina to investigate the relationship between the microvascular density, the foveal thickness and visual acuity. The density of STMI and SMIR decreased in macular area in the patients with CSCR compared to the normal controls (P<0.05), while the density of SMAR did not change significantly. We found no significant difference in the density of SMIR with the quadrant partition method, whereas the annular partition method showed significantly decreased SMIR density only in the C1 region in patients with CSCR (P<0.05), with no significant difference observed in C2-C6 regions. The density of SMIR had the highest differentiation power in the CSCR group, whereas the density of SC1 ring had the lowest differentiation power by the annular method. The largest area under the ROC curves was 0.77. The correlation index of the SMIR density and visual acuity was −0.544, whereas macular thickness and visual acuity was −0.644 in the CSCR group. The density of STMI and SMIR were decreased in patients with CSCR, which might provide further understanding of the pathogenesis of CSCR.

Chronic Central Serous Chorioretinopathy in a Patient with Pigment Dispersion Syndrome: A Possible Correlation

Chronic central serous chorioretinopathy (CSCR) is a progressive chorioretinopathy with widespread atrophic RPE abnormalities and serous retinal detachments (SRDs) present for 6 months or longer. We report a case of CSCR in a 38-year-old patient with Pigment Dispersion Syndrome (PDS). In the presented case of CSCR, the chronic course of the disease may in part be associated with an underlying generalized degenerative dysfunction of the pigmented cells of the eye on grounds of PDS. We suggest that a chronic course of disease may be suspected in the setting of CSCR with concurrent RPE pathology, such as what is found in PDS.