Vessel Pulse Amplitude Mapping in Eyes With Central and Hemi Retinal Venous Occlusion.

Purpose: The purpose of this study was to describe vessel pulse amplitude characteristics in eyes with central retinal vein occlusion (CRVO), hemiretinal vein occlusion (HVO), normal eyes (N1 N1), and the unaffected contralateral eyes of CRVO and HVO eyes (N1 CRVO and N1 HVO), as well as the unaffected hemivessels of HVO eyes (N2 HVO). Methods: Ophthalmodynamometry estimates of blood column pulse amplitudes with modified photoplethysmography were timed against cardiac cycles. Harmonic analysis was performed on the vessel reflectance within 0.25 to 1 mm from the disc center to construct pulse amplitude maps. Linear mixed modeling was used to examine variable effects upon the log harmonic pulse amplitude. Results: One hundred seven eyes were examined. Normal eyes had the highest mean venous pulse amplitude (2.08 ± 0.48 log u). CRVO had the lowest (0.99 ± 0.45 log u, P < 0.0001), followed by HVO (1.23 ± 0.46 log u, P = 0.0002) and N2 HVO (1.30 ± 0.59 log u, P = 0.0005). N1 CRVO (1.76 ± 0.34 log u, P = 0.52) and N1 HVO (1.33 ± 0.37 log u, P = 0.0101) had no significantly different mean amplitudes compared to N1 N1. Arterial amplitudes were lower than venous (P < 0.01) and reduced with venous occlusion (P < 0.01). Pulse amplitude versus amplitude over distance decreased along the N1 N1 vessels, with increasing slopes observed with CRVO (P < 0.01). Conclusions: Pulse amplitude reduction and attenuation characteristics of arteries and veins in venous occlusion can be measured and are consistent with reduced vessel wall compliance and pulse wave transmission. Translational Relevance: Retinal vascular pulse amplitudes can be measured, revealing occlusion induced changes, suggesting a role in evaluating the severity and progression of venous occlusion.

Use of trypan blue to assess lymphatic function following trabeculectomy.

IMPORTANCE: To illustrate the importance of lymphatic drainage in assessing trabeculectomy bleb function using intracameral trypan blue. BACKGROUND: To study the lymphatic drainage of trabeculectomy blebs using trypan blue, correlate with bleb function and classify them accordingly. DESIGN: Prospective cross-sectional study in a tertiary care centre. PARTICIPANTS: Thirteen glaucoma patients post-trabeculectomy were studied. METHODS: Trypan blue was injected into the anterior chamber. MAIN OUTCOME MEASURES: The duration taken for dye to stain a drainage bleb or lymphatics is recorded. The extent of the lymphatic structures were measured in clock hours. Intraocular pressure (IOP) prior to surgery was recorded. RESULTS: Eight post-trabeculectomy subjects with dye stained lymphatic vessels had lower IOP (12.6 mmHg, P = .013) compared to the five with no lymphatic vessel staining (mean IOP 23.6 mmHg). Lymphatic extent was inversely related to IOP (P = .021). CONCLUSIONS AND RELEVANCE: Eyes with lymphatic connections to drainage blebs had lower IOP and reduced requirement for topical medications. The extent of lymphatic connection to drainage blebs is related to lower IOP.

Use of trypan blue as an aqueous tracer dye to investigate hypotony where cyclodialysis cleft is suspected.

IMPORTANCE: A new method to help diagnose suspected cyclodialysis clefts. BACKGROUND: To study the use of trypan blue stained aqueous flow patterns in diagnosing causes of hypotony where cyclodialysis clefts were suspected. DESIGN: A case series in a tertiary care centre. PARTICIPANTS: Ten subjects presenting with persistent hypotony and retinal changes. METHODS: Trypan blue was injected into the anterior chamber. MAIN OUTCOME MEASURES: The pattern of dye flow in the anterior chamber was categorized. Intraocular pressure prior to surgery was recorded. RESULTS: All seven subjects with cyclodialysis clefts had a preferential flow to the cleft region. Two hypotonous subjects post trabeculectomy had rapid (5 seconds) and extensive lymphatic staining (6 o'clock hours extent) without visible bleb formation. CONCLUSIONS AND RELEVANCE: Preferential flow of dye to the limbus is a reliable sign of cyclodialysis cleft and helps localize cleft extent. A new cause of hypotony, "lymphatic overdrain," is identified.