Generating retinal flow maps from structural optical coherence tomography with artificial intelligence.

Despite advances in artificial intelligence (AI), its application in medical imaging has been burdened and limited by expert-generated labels. We used images from optical coherence tomography angiography (OCTA), a relatively new imaging modality that measures retinal blood flow, to train an AI algorithm to generate flow maps from standard optical coherence tomography (OCT) images, exceeding the ability and bypassing the need for expert labeling. Deep learning was able to infer flow from single structural OCT images with similar fidelity to OCTA and significantly better than expert clinicians (P < 0.00001). Our model allows generating flow maps from large volumes of previously collected OCT data in existing clinical trials and clinical practice. This finding demonstrates a novel application of AI to medical imaging, whereby subtle regularities between different modalities are used to image the same body part and AI is used to generate detailed inferences of tissue function from structure imaging.

Familial retinal arteriolar tortuosity and quantification of vascular tortuosity using swept-source optical coherence tomography angiography.

PURPOSE: Familial retinal arteriolar tortuosity (FRAT) is a rare autosomal dominant disorder that is characterized by tortuosity of the second and higher order retinal arterioles. We implement swept-source optical coherence tomography angiography (SS-OCTA) to quantify vessel tortuosity in patients with FRAT. We hypothesize that patients with FRAT will have higher retinal arteriole tortuosity when compared to controls. METHODS: Patients were scanned with a SS-OCTA device (Plex Elite 9000, Carl Zeiss Meditec, Dublin, CA). Images of a 12 × 12 mm2 area centered on the fovea were processed, and retinal vessels >23.5 µm in diameter were identified. An automatic tortuosity measurement program written in MATLAB was used to assess vessel tortuosity. Branch points in the vessels were detected and used to separate the vasculature into individual segments. The tortuosity was measured by calculating the arc-chord ratio of each vessel segment, where a minimum value of 1 indicated a straight vessel and higher values corresponded to increasing tortuosity. RESULTS: Two patients (4 eyes) with a known history of FRAT and six controls (12 eyes) were enrolled in the study. The mean tortuosity of all vessel segments (MTVS) in scans of FRAT eyes was on average 1.1244 [range: 1.1044-1.1438] while for control eyes it was 1.0818 [range: 1.0746-1.0872]. Average MTVS of FRAT eyes was significantly higher compared to control eyes (p = 0.03). CONCLUSIONS AND IMPORTANCE: Our results are consistent with the hypothesis that patients with FRAT have higher objective measurements of tortuosity compared to controls. Broader applications of this method may be of benefit in other retinal diseases with changes in retinal vessel configuration.

Traumatic Ptosis: Evaluation of Etiology, Management and Prognosis.

INTRODUCTION: To investigate whether a systematic approach to subgrouping traumatic ptosis according to etiology can allow for better tailoring of prognosis and treatment. METHODS: Retrospective chart review of patients with trauma-related blepharoptosis managed by Oculoplastic surgery specialists at an academic medical center from January 1995 to November 2015. Injury mechanism, eyelid position and function, interventions, and outcomes were reviewed. RESULTS: Of 648 patients treated for blepharoptosis, 55 (8.5%) were traumatic. Careful review revealed 4 subcategories of traumatic ptosis cases: aponeurotic (n = 16), myogenic (n = 18), neurogenic (n = 7), and mechanical (n = 14). Margin reflex distance (MRD1) at presentation was significantly worse for the myogenic subtype (-0.59 mm, SD ±2.09, P = 0.046). The aponeurotic subtype had the best average levator function at presentation (14.29 mm, SD ±2.05), while myogenic had the worst (8.41 mm, SD ±4.94) (P = 0.004). Thirty-five (63.6%) patients were managed surgically. Final MRD1 was significantly different for each subtype (P = 0.163), with aponeurotic 2.63 mm (SD ±1.01), myogenic 1.29 mm (SD ±2.24), neurogenic 1.79 mm (SD ±2.48), and mechanical 2.31 mm (SD ±1.18). There was a significant increase in MRD1 from presentation to final follow up across all groups (P < 0.05). CONCLUSION: Traumatic ptosis is heterogenous. Systematically evaluating traumatic ptosis cases by trauma mechanism can guide decisions about prognosis and management. Two-thirds of cases were treated surgically, with most patients responding well to conjunctiva-Müller resection or external levator advancement. While all subgroups demonstrated improvement in MRD1 at final follow up, aponeurotic cases had the best prognosis, while myogenic fared the worst and required the longest for maximal recovery.

Triamcinolone Acetonide-Assisted Descemetectomy for Retained Descemet Membrane.

We present a case of decreased vision due to the presence of retained Descemet membrane (DM) following Descemet stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty (PKP). A 78-year-old male presented postoperatively from PKP after previous failed DSAEK with retained DM. We present a unique technique for combined surgical resection using bimanual vitrectomy and forceps excision assisted by triamcinolone acetonide for membrane visualization. Histopathological evaluation confirmed incomplete DM removal during the PKP. With surgical excision, there was an improvement in best spectacle-corrected visual acuity from 20/80 to 20/30.

Deep-learning based, automated segmentation of macular edema in optical coherence tomography.

Evaluation of clinical images is essential for diagnosis in many specialties. Therefore the development of computer vision algorithms to help analyze biomedical images will be important. In ophthalmology, optical coherence tomography (OCT) is critical for managing retinal conditions. We developed a convolutional neural network (CNN) that detects intraretinal fluid (IRF) on OCT in a manner indistinguishable from clinicians. Using 1,289 OCT images, the CNN segmented images with a 0.911 cross-validated Dice coefficient, compared with segmentations by experts. Additionally, the agreement between experts and between experts and CNN were similar. Our results reveal that CNN can be trained to perform automated segmentations of clinically relevant image features.

Optic nerve head morphology in glaucoma patients of African descent is strongly correlated to retinal blood flow.

BACKGROUND/AIMS: To examine the relationship between change in optic nerve head (ONH) morphology and retinal blood flow in patients with open-angle glaucoma (OAG) of African (AD) and European descent (ED) over 3 years. METHODS: 112 patients with OAG (29 AD; 83 ED) underwent assessment of ONH morphology using Heidelberg retinal tomography (HRT-III), and retinal blood flow using confocal scanning laser Doppler. Repeated-measures analysis of covariance was used to compare baseline and 3-year measurements, and Pearson correlations were calculated to evaluate the relationships. RESULTS: In OAG patients of AD, change in superior mean retinal blood flow was strongly, negatively correlated with change in cup/disc (C/D) area ratio (r=-0.78, p=0.020) and cup area (r=-0.75, p=0.0283) and strongly, positively correlated with change in rim area (r=0.74, p=0.0328) over 3 years. In OAG patients of AD, change in inferior mean retinal blood flow was strongly, negatively correlated with changes in C/D area ratio (r=-0.88, p=0.0156) and linear C/D ratio (r=-0.86, p=0.0265) over 3 years. In OAG patients of ED, these correlations were weak and did not reach statistical significance. DISCUSSION: OAG patients of AD may have a stronger vascular component to their glaucoma pathophysiology than patients of ED.