Evaluation of diabetic retinopathy severity on ultrawide field colour images compared with ultrawide fluorescein angiograms.

PURPOSE: To compare Early Treatment Diabetic Retinopathy Study (ETDRS) diabetic retinopathy (DR) severity on ultrawide field (UWF) colour imaging (CI) and UWF fluorescein angiography (FA). DESIGN: Cross-sectional retrospective review. SUBJECTS: Patients with diabetes mellitus and at least mild non-proliferative DR on UWF-CI. METHODS: UWF-CI and UWF-FA images acquired within 1 month of each other were evaluated independently using ETDRS DR Severity Scale (DRSS) for colour photography adapted for UWF-CI and UWF-FA. Extent of non-perfusion (NP, mm2) was determined from UWF-FA images. MAIN OUTCOME MEASURES: Agreement rate between DRSS on UWF-CI and UWF-FA. RESULTS: Images from 218 eyes of 137 patients with diabetes were evaluated. Agreement rate for DRSS between UWF-CI and UWF-FA was moderate to substantial (K=0.46, Kw=0.65). Over-all, DRSS was worse in 73 (33.5%) eyes on UWF-FA and in 16 (7.3%) on UWF-CI. Compared to UWF-CI, UWF-FA identified more severe DRSS in 26.5% (1 step) and 7.34% (≥2 steps) of eyes. DRSS was worse than UWF-FA in 56 (51.4%) in early DR (ETDRS levels 20-47, N=109) and 17 (15.6%) in eyes with severe DR (53 and higher, N=109). In this cohort, the extent of NP significantly increased as eyes approach moderate non-proliferative DR (levels 43-47, p=0.0065). CONCLUSION: When evaluating UWF-FA images using the ETDRS colour severity scale, DRSS is graded as more severe in a substantial number of eyes than when evaluating UWF-CI. It is uncertain how the DRSS levels using UWF-FA translate to clinical outcomes, but the additional lesions detected might provide added prognostic value. These and other recent data emphasise the need of obtaining outcome data based on UWF-FA and the potential need to develop DRSS specifically tailored for UWF-FA images.

Retinal Vascular Caliber Association with Nonperfusion and Diabetic Retinopathy Severity Depends on Vascular Caliber Measurement Location.

PURPOSE: To evaluate the association of retinal nonperfusion and diabetic retinopathy (DR) severity with location of vascular caliber measurement using ultrawide field (UWF) imaging. DESIGN: Retrospective image review. PARTICIPANTS: Adults with diabetes mellitus. METHODS: All images from subjects with same-day UWF fluorescein angiography (FA) and color imaging were evaluated. Predominantly peripheral lesions (PPL) and DR severity were graded from UWF color images. Nonperfusion was quantified using UWF-FA in defined retinal regions [posterior pole (PP), mid-periphery (MP), far-periphery (FP)]. Retinal vessel calibers were measured at an optic disc centered inner and outer zone. MAIN OUTCOME MEASURES: Nonperfusion index (NPI) in the PP, MP and FP. Mean arteriole and venule diameter in the inner and outer zones. RESULTS: Two hundred eighty-five eyes of 193 patients (24.9% mild nonproliferative DR [NPDR], 22.8% moderate NPDR, 37.5% severe NPDR and 14.7% proliferative DR [PDR]) were reviewed. No significant associations between inner zone arteriolar diameter and retinal NPI overall or in any retinal region. In the outer zone, eyes with thinnest arteriolar calibers (quartile 1) were associated with a 1.7- to 2.4-fold nonperfusion increase across all retinal regions compared to the remaining eyes (P = 0.002 [PP] to 0.048 [FP]). In the outer zone, the percentage of eyes in the thinnest quartile of retinal arteriolar diameter increased with worsening DR severity (mild NPDR: 10% vs PDR: 31%, P = 0.007). This association was not observed when measured within the inner zone (P = 0.129). All venular caliber associations were not statistically significant when corrected for potentially confounding factors. Thinner outer zone retinal arteriolar caliber (quartile 1) was more common in eyes with PPL compared to eyes without PPL (34.1% vs 20.8%, P = 0.017) as were thicker outer venular calibers (quartile 4) (33% vs 21.3%, P = 0.036). Presence of PPL was associated with thinner outer zone arteriolar caliber (109.7 ± 26.5µm vs 123.0 ± 29.5µm, P = 0.001). CONCLUSIONS: The association of vascular caliber with nonperfusion and DR severity differs based upon the retinal location at which vascular caliber is measured. Peripheral arterial narrowing is associated with increasing nonperfusion, worsening DR severity and presence of PPL. In contrast, inner zone retinal arteriolar caliber is not associated with these findings.

Disparity of microaneurysm count between ultrawide field colour imaging and ultrawide field fluorescein angiography in eyes with diabetic retinopathy.

AIMS: To compare microaneurysm (MA) counts using ultrawide field colour images (UWF-CI) and ultrawide field fluorescein angiography (UWF-FA). METHODS: Retrospective study including patients with type 1 or 2 diabetes mellitus receiving UWF-FA and UWF-CI within 2 weeks. MAs were manually counted in individual Early Treatment Diabetic Retinopathy Study (ETDRS) and extended UWF zones. Fields with MAs ≥20 determined diabetic retinopathy (DR) severity (0 fields=mild, 1-3=moderate, ≥4=severe). UWF-FA and UWF-CI agreement was determined and UWF-CI DR severity sensitivity analysis adjusting for UWF-FA MA counts performed. RESULTS: In 193 patients (288 eyes), 2.4% had no DR, 29.9% mild non-proliferative DR (NPDR), 32.6% moderate (NPDR), 22.9% severe NPDR and 12.2% proliferative DR. UWF-FA MA counts were 3.5-fold higher (p<0.001) than UWF-CI counts overall, 3.2x-fold higher in ETDRS fields (p<0.001) and 5.3-fold higher in extended ETDRS fields (p<0.001) and higher in type 1 versus type 2 diabetes (p<0.001). In eyes with NPDR on UWF-CI (n=246), UWF-FA images had 1.6x-3.5x more fields with ≥20 MAs (p<0.001). Fair agreement existed between imaging modalities (k=0.221-0.416). In ETDRS fields, DR severity agreement increased from k=0.346 to 0.600 when dividing UWF-FA counts by a factor of 3, followed by rapid decline in agreement thereafter. Total UWF area agreement increased from k=0.317 to 0.565 with an adjustment factor of either 4 or 5. CONCLUSIONS: UWF-FA detects threefold to fivefold more MAs than UWF-CI and identifies 1.6-3.5-fold more fields affecting DR severity. Differences exist at all DR severity levels, thus limiting direct comparison between the modalities. However, correcting UWF-FA MA counts substantially improves DR severity agreement between the modalities.

"For Mass Eye and Ear Special Issue" Adaptive Optics in the Evaluation of Diabetic Retinopathy.

Retinal imaging is a fundamental tool for clinical and research efforts in the evaluation and management of diabetic retinopathy. Adaptive optics (AO) is an imaging technique that enables correction of over 90% of the optical aberrations of an individual eye induced primarily by the tear film, cornea and lens. The two major tasks of any AO system are to measure the optical imperfections of the eye and to then compensate for these aberrations to generate a corrected wavefront of reflected light from the eye. AO scanning laser ophthalmoscopy (AOSLO) provides a theoretical lateral resolution limit of 1.4 µm, allowing the study of microscopic features of the retinal vascular and neural tissue. AOSLO studies have revealed irregularities of the photoreceptor mosaic, vascular loss, and details of vascular lesions in diabetic eyes that may provide new insight into development, regression, and response to therapy of diabetic eye disease.