Abstract
Purpose :
Colour Doppler Imaging (CDI) is helpful in detecting and getting blood velocity waveforms of blood vessels which contribute in retrobulbar circulation. We tested the hypothesis that there is vascular compromise in glaucoma patients, which may be one of the main factors responsible for damage to the optic nerve. We used CDI to compare the blood flow velocities { Peak systolic velocity (PSV) and End diastolic velocity (EDV)} and Resistive index (RI) in the central retinal artery (CRA) of patients with primary open angle glaucoma (POAG) to that of normal control population.
Methods :
Patients with POAG fulfilling two of three selection requirements (intraocular pressure (IOP) consistently above 21±1 mmHg, reproducible visual field defects, and glaucomatous optic nerve appearance) and willing to participate in the study were placed in Group I. Normal healthy volunteers matched for age and sex with Group I, having IOP < 21 mmHg, normal optic disc and visual fields constituted Group II. Blood flow velocity was recorded from Doppler frequency shifts displayed as spectral waveform. PSV and EDV were measured, and RI was obtained as an angle independent ratio RI = PSV – EDV/PSV
Results :
The mean IOP of Group I was found to be significantly higher than that of Group II (p=0.039). Although the perfusion pressure in Glaucoma patients was slightly lower than normal subjects, the difference was not statistically significant (p=0.413). Similarly, the PSV of Group I was lower than Group II, but the difference was statistically insignificant (p=0.869). The EDV in Group I was significantly lower compared to Group II (p=0.000). Ultimately, the mean RI of Group I was higher than that of Group II, thus the difference in RI was statistically significant (p=0.000).
Conclusions :
Higher systolic blood pressure and higher IOP were found to be significantly associated with raised CRA vascular resistance. Raised CRA resistance was found to be a major determinant of optic nerve hypoperfusion. Hence, colour Doppler can be used in cases of POAG on a regular basis and it can be a reliable investigation to assess vascular compromise in glaucoma patients. CDI can also help to evaluate the severity of the disease and its progression and efficacy of treatment in glaucoma patients. CDI can prove to be very helpful in patients with normal tension glaucama where IOP is in normal range.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.