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Louis R Pasquale, Clara Cousins, Billy Pan, Jonathan C Chou, Lucy Q Shen, Mae Gordon, Michael Kass, Robert Ritch; Densitometry and geometry of optic disc hemorrhages in the Ocular Hypertension Treatment Study. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2848.
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We previously found that glaucomatous optic disc hemorrhages (DH) in a clinic-based sample from Mass Eye and Ear (MEE) tended to be arterial in origin based on DH densitometry assessments [PMID: 29330062]. In this study, we assessed DH densitometry in Ocular Hypertension Treatment Study (OHTS) patients and compared DH geometric features to the previously-published sample from MEE to determine whether DH have different characteristics in patients with higher baseline intraocular pressure (IOP) and minimal optic nerve change versus definitive damage.
We used ImageJ software to measure densitometry differentials (adjacent arteriole minus DH [ΔA] and adjacent venule minus DH [ΔV]) in 161 DH images from the OHTS (Figure). For each DH we also assessed size as a percentage of disc area and the ratio of the DH’s length (radial) to its midpoint width. We performed t tests to compare the densitometry and geometric profiles of DH in the OHTS versus 40 historical DH from MEE.
Mean (standard deviation [SD]) IOP was 26.0 (2.8) mmHg and 19.5 (5.0) mmHg in DH eyes from the OHTS and MEE, respectively (P<0.001). Mean baseline MD on Humphrey visual field testing in OHTS was -1.15 (2.73) dB while it was -3.60 (2.96) dB closest to imaging of the DH in MEE (p<0.001). Among DHs from the OHTS patients, mean (SD) for ΔA was -2.2 (8.7) pixel intensity units and mean (SD) for ΔV was -11.4 (9.7) pixel intensity units (P for ΔA vs. ΔV < 0.001). The mean (SD) length-to-width ratio of DHs was smaller in OHTS (3.0 (2.0)) vs. the MEE sample (4.9 (2.5); P<0.001). The mean size of DH (SD) as a percentage of disc area was also smaller in OHTS 2.3% (3.4%) compared to MEE (4.3% (4.5%); P=0.011). Among OHTS subjects with recurrent DH (n=38 patients), subsequent mean ΔA (1.9 (7.7)) and ΔV (-11.8 (11.0)) were comparable to the values obtained at the initial DH event (P>0.92).
DH from OHTS patients had densitometry measurements consistent with a predominantly arterial origin, a finding similar to that obtained in a prior clinic-based sample. However, the DH in OHTS were smaller and less elongated compared to a historic clinic-based sample with lower baseline IOP. More work is needed to understand how DH develop.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Densitometry measurements were obtained within the black box. For this patient, the hemorrhage’s length-to-width ratio is 2.03 and size as percentage of disc area is 0.53%.
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