Glaucomatous optic neuropathy (GON) is the core of primary glaucoma. Alongside with ophthalmohypertension and specific changes of visual fields the GON enters into the triad of this disease cardinal symptoms (Yegorov Ye.A., 2002, Alyabyeva Zh.Yu., 2004). The GON pathogenesis includes some factors, one of which is a vascular one - optic nerve head microcirculation disorders (tendency to vasospasms, rheological disorders, venous stasis, perfusion pressure decrease) (Grigoryeva Ye.G., 2002, Galassi F., 2003). However, in spite of native and foreign researchers´ works on the ocular blood flow study, the possibilities of modern eye circulatory dynamics and orbital region research methods have not been studied to the end by the present time.
The purpose is to study the circulatory dynamics in primary open-angle glaucoma (POAG) patients in the ophthalmic artery and central retinal artery by the ultrasonic duplex scanning method with color doppler mapping.
Materials and methods
Patients with obstructive affections in internal and external carotid arteries´ regions were excluded from the examination.
We examined 38 patients (38 eyes) with the diagnosis of I-IV stage POAG (the main group). Among them, the I stage was registered in 9 patients, II stage - in 11, III - in 11 and IV - in 7 patients. In all the patients the intraocular tension (IOT) was normalized medicamentally or surgically and averaged 19, 4±2, 6 mm hg.
The control group was made up of 20 patients (20 eyes) with mature age-dependent cataract without glaucoma signs. The average age of both groups patients made 68, 3 + 2, 4 years old.
The circulatory dynamics investigation was carried out on the multipurpose ultrasonic high definition imaging system (HDI - High Definition Imaging System) HDI 1500 of the ALT firm, USA, with a broad-band linear transducer of 5-12 mHz. The valuation of hemodynamic parameters was performed in the following vessels: ophthalmic artery and central retinal artery.
The ophthalmic artery was located with the help of the 5MHz frequency transducer, at the depth of 38-42 mm at the vessel´s entry into the orbital cavity, transbulbarily through the patient´s closed eye-lids. The patient´s gaze direction was inward and downward. The pathfinder position is upper-external quadrant of the eye-bulb. The location direction - is to the orbital height, 15-30 ° from the median line.
The central retinal artery was defined at scanning plane passing through the optic disk. The blood flow investigation in this artery was performed within the region of 0-10 mm from the place of its entering into the optic nerve trunk thickness up to the eye-bulb, with the following valuation of all parameters.
At the investigation findings analysis the following Doppler frequency shift spectrum parameters were evaluated:
- maximum systolic velocity (V syst., cm/sec);
- end diastolic velocity (V diast., cm/sec);
- average blood velocity (V m., cm/sec);
- resistance index (RI).
It is found out that the maximum systolic velocity is the least variable parameter in the POAG patients. There are no statistically-valid V syst. values differences with those in the control group registered (p<0, 05).
The average blood velocity in the ophthalmic artery in the main group patients decreased against the control group with the disease progression; the deviation from the control being authentic (p<0, 01) at the I stage POAG. Thereafter (II-IV stages) a gradual average blood velocity decrease was registered. it testifies to the importance of this factor in the progression of the process.
At the analysis of the end-diastolic blood velocity changes as the vascular resistance factor, the data were got that a slight V diast. decrease, authentically differing from the norm at the III and IV stages only (p<0, 05), takes place at the II-IV stages of the disease. The peripheral resistance index is in the inverse linear dependence on the end-diastolic velocity value (the lower the velocity - the higher the index value, and vice versa), that is why the RI dynamics in the ophthalmic artery according to the glaucoma stages was inversely as the described above changes of the end-diastolic velocity. The changes found out in the CRA look like this: At the initial stages of glaucoma The V syst. in the CRA decreased 1, 4 times compared to the control group. The Vm. at the OAG initial stage was 1, 5 times as lower. The CRA diastolic blood velocity was decreased beginning with the I stage (p<0, 05) and also decreased with the glaucoma progression. The maximal CRA diastolic velocity fall was registered at the IV stage of glaucoma; the diastolic component being missing in one case. It was found out that the peripheral resistance indexes in OAG patients, beginning with the I stage of the disease, is authentically higher than in the group of control.
Ultrasonic methods of diagnostics using Doppler methods allow evaluating quantitative blood flow indexes in the ophthalmic artery and its branches at various stages of open-angle glaucoma, that affords an opportunity to come around to the diagnostics, treatment and prognostication of its course in a more detailed way.
The work was submitted to III international scientific conference «Actual problems of science and education», Cuba, March, 19-29, 2008, came to the editorial office 17.01.2008