[Intraocular pressure, ocular blood flow, and corneal biomechanics changes after LASIK surgery for myopia]. / Vliyanie operatsii LASIK pri miopii na pokazateli oftal'motonusa, ob''emnogo glaznogo krovotoka i «biomekhaniki¼ rogovitsy.

AIM: to study changes in intraocular pressure (IOP), volumetric ocular blood flow (OBF) rate, and biomechanical properties of the cornea after excimer laser ablation in patients with myopia of different degrees. MATERIAL AND METHODS: A total of 16 patients (32 eyes) with myopia ranging from 2.75 to 9.0 D were examined before and after LASIK. Ocular Blood Flow Analyzer (OBFA) was used to measure IOP and OBF as well as pulse amplitude and volume. Ocular Response Analyzer (ORA) was also employed to provide the following data: Goldmann-equivalent IOP, corneal compensated IOP, corneal hysteresis, and corneal resistance factor. The eyes were then divided into two groups: group 1 - 15 eyes with less than 70-µm deep ablation of the cornea and group 2 - 17 eyes with more than 70-µm deep ablation. RESULTS: Group 1 demonstrated a statistically reliable decrease in IOP values provided by either method and biomechanical parameters of the cornea (p<0.005), but no difference in pre- and postoperative OBF, or pulse amplitude, or pulse volume (p>0.05). In group 2, all the parameters changed reliably, except for the pulse volume (p>0.05). In particular, a decrease was recorded for IOP (with no dependence to the method of measurement; p<0.001), pulse amplitude (p<0.01), corneal hysteresis (p<0.001), and corneal resistance factor (p<0.001); an increase - for OBF (p<0.05). CONCLUSION: One should allow for possible mismeasurement of IOP and OBF as well as biomechanical parameters of the cornea in post-LASIK patients, keeping in mind that the extent of error depends on the depth of ablation. Shallow ablation (no more than 70-µm deep) has no statistically significant effect on OBF readings, while IOP seems to decrease considerably. In deep ablation (more than 70-µm deep), both parameters are reliably lower than at baseline.

[Tomography findings in optic nerve head and retina in differential diagnosis between normal-tension glaucoma and ischemic optic neuropathies].

AIM: to determine tomography findings in optic nerve head (ONH) and retinal nerve fiber layer (RFNL) that may be valuable for differential diagnosis between normal-tension glaucoma (NTG) and ischemic optic neuropathy (ION) outcome. MATERIAL AND METHODS: Group 1 consisted of 17 patients (32 eyes) with NTG, group 2--17 patients (24 eyes) with ION outcome. The control group included 22 patients (22 eyes) with no sighs of optic neuropathy. Optic nerve head and retina assessment included scanning laser ophthalmoscopy (HRT 111) and optical coherence tomography (Stratus OCT 3000). Statistical analyses were performed using Statistica 10 software suite. RESULTS: Statistically significant changes in HRT parameters, namely, the mean RNFL thickness, retinal height variation along the contour line, and RB discriminant function, were observed in both study groups as compared to the controls. NTG patients also showed lower rim indices, larger cups, smaller values of the FSM discriminant function, and lower GPS (glaucoma probability score) than both ION patients and the controls. OCT findings included a statistically significant decrease in RNFL thickness in both study groups as compared to the controls. As for the difference between the groups, it was unreliable. Quadrant comparisons of RNFL thicknesses revealed that lower quadrant RNFL thinning was more significant in NTG patients, while temporal quadrant RNFL thinning--in ION patients. CONCLUSION: Both conditions are associated with a similar degree of RNFL thinning, as confirmed by OCT, however, HRT changes are much more pronounced in NTG than in ION patients.

[Effects of blood flow properties on ocular hemodynamics].

AIM: to study the effects of blood rheology on ocular blood flow (OBF) parameters and estimated individual normal range of intraocular pressure (IOP). MATERIAL AND METHODS: A total of 15 patients (15 eyes) taking warfarin were enrolled. Volumetric parameters and linear velocity of OBF under warfarin treatment and after its cessation were obtained by means of flowmetry (Paradigm's Blood Flow Analyzer) and color Doppler flow mapping (Voluson 730), respectively. On the basis of flowmetry results an individual normal range of IOP was calculated in all patients. RESULTS: Pulsatile OBF does not appear to correlate with warfarin-induced changes in blood rheology (p = 0.09), however, depends on IOP fluctuations (p = 0.02). Resistance index of retinal vessels is found to rise significantly with increasing blood viscosity (p < 0.05). CONCLUSION: The use of warfarin, an indirect thrombin inhibitor, has no effect on estimated individual normal range of IOP, which is crucial for glaucoma diagnosis and monitoring.

[Ocular blood flow and carotid artery malfunction].

AIM: to evaluate ocular hemodynamics and informativity of estimated individual normal range of intraocular pressure (IOP). MATERIALS AND METHODS: A total of 12 patients (22 eyes) with carotid artery malfunction were examined. Ocular blood flow (OBF) and IOP were measured with Ocular Blood Flow Analyzer. Actual OBF was then compared with what is considered normal for a given axial length (AL). Individual normal range of IOP was calculated according to an original formula (described in previous publications). Doppler imaging of ocular vessels enabled blood flow velocity measurement. Morphological parameters and functional status of the retina and optic nerve were judged on automated perimetry (Octopus 900) and optical coherence tomography (Cirrus HD-OCT) findings. Statistical analyses were performed using Statistica 10 software. RESULTS: Generally, OBF showed no correlation with the grade of carotid artery stenosis (p < 0.05), however, was significantly reduced as compared to its AL-dependent norm in patients with greater than 85% narrowing of the internal carotid artery, which can cause misestimating of their individual normal range of IOP. A negative relationship was established between the blood flow velocity in short posterior ciliary arteries and the grade of internal carotid artery stenosis (p < 0.005). Ocular blood flow deficit relative to the AL-dependent norm correlated with ophthalmic artery resistance index. CONCLUSION: OBF-based estimation of individual normal range of IOP is inexpedient in patients with greater than 80% carotid artery stenosis due to its possible influence on ocular hemodynamics. In most cases of less than 80% carotid artery stenosis OBF is adequate or slightly reduced as compared to its AL-dependent norm and thus, has no significant impact on estimated individual normal range of IOP.

[Determination of the individual normal range of intraocular pressure in differential diagnosis between pseudonormal tension glaucoma and ischemic optic neuropathies].

The study investigated the relation between the actual intraocular pressure (IOP) and its individual normal range in normal-tension glaucoma (NTG) and ischemic optic neuropathy (ION) outcome. A total of 39 patients (61 eyes) were examined. Group 1 included 19 patients (35 eyes) with newly diagnosed NTG, group 2--20 patients (26 eyes) with the ION outcome. Besides conventional tests, the ophthalmic assessment in all patients included determination of the individual normal range of IOP and evaluation of biomechanical properties of the cornea. It is showed that determination of the individual normal range of IOP may play a key role in confusing cases of differential diagnosis between NTG and ION. The average actual IOP in patients with NTG generally exceeds the individual normal range by 40% (more than 5 mmHg), whereas in patients with the ION outcome--by only 11.7% (less than 5 mmHg - buffer range). No statistically significant difference in IOP measurements by different tonometry methods was found in either NTG or ION patients with corneal compensated IOP less than 21 mmHg.

[Intraocular pressure and ocular blood flow features intravitreal infection of anti-vascular endothelial growth factor agents].

OBJECTIVE: to investigate intraocular pressure (IOP) and ocular blood flow (OBF) changes as well as the individual normal range of IOP in patients with age-related macular degeneration (AMD) with or without concomitant glaucoma after intravitreal anti-vascular endothelial growth factor (VEGF) therapy. MATERIAL AND METHODS: Group 1 included 34 patients (34 eyes) with AMD and no glaucoma, group 2-34 patients (34 eyes) with both AMD and glaucoma. In all patients the IOP and OBF were measured (with Ocular Blood Flow Analyzer) and the individual normal range of lOP calculated before the treatment, on the third day after the injection and at the 1-month follow-up visit. Statistical analysis was performed by STATISTICA 10. RESULTS: In group 1 there were no significant changes in ocular blood flow at different times after ranibizumab injection. In group 2 a considerable decrease in OBF was detected 1 month after the injection (p<0.001). In group 1 the intraocular pressure was at the same level before and after the treatment. In group 2 the IOP significantly decreased on the third day after the anti-VEGF injection (p=0.03) but was back to the initial level in 1 month. The individual normal range of lOP, when calculated on the third day after the injection, appeared to be much lower than before due to a moderate decrease in both IOP and OBF. At the 1-month follow-up the individual normal range of IOP was back to initial values in non-glaucoma patients but remained low in the glaucoma group due to reduced OBF. CONCLUSION: The established decrease in the individual normal range of IOP in the late period after an anti-VEGF injection should be taken into account when managing patients with both AMD and glaucoma.

[Peculiarities of ocular blood flow in ischemic optic neuropathy and normal tension glaucoma].

Characteristics of ocular hemodynamics in ischemic optic neuropathy (ION) outcome and normal tension glaucoma (NTG), the conditions that are difficult to be differentially diagnosed, have been investigated. The study enrolled 32 patients (40 eyes) with ION outcome, 26 patients (46 eyes) with NTG, and 20 patients (32 eyes) with no ocular pathology. Besides the standard ophthalmological examination, color Doppler imaging of ocular vessels, evaluation of ocular blood flow volume and individual normal range of intraocular pressure (flowmetry) were performed in all cases. The results showed that an excess of the actual intraocular pressure (IOP) over the individual normal range was much higher in patients with NTG than in patients with ION (39% and 14.5% correspondingly). It was also found that NTG is associated with a more significant decrease of ocular blood flow volume (30.1% in average) in comparison to ION outcome (11%). In both conditions a decrease in velocity parameters of the blood flow in main ocular vessels was registered, however, ocular hemodynamics changes appeared to be more severe in patients with glaucomatous optic neuropathy. A statistically reliable correlation between volumetric and velocity parameters of ocular blood flow has been discovered.

[Hemodynamic changes in myopia of different degrees].

A total of 78 patients (143 eyes) with low, medium and high degree myopia were assessed. Apart from standard ophthalmological tests, flowmetry and duplex ultrasound of ocular vessels were performed in all cases to evaluate volumetric and velocity parameters of ocular blood flow in relation to the length of anterior-posterior axis and the degree of myopia. It is found that both parameters of regional blood flow progressively decrease as the anterior-posterior axis increases.

[Comparative analysis of several morphometric parameters received using optic coherent tomography and scanning laser ophthalmoscopy in initial glaucoma diagnosis].

Retinal morphometric parameters received using confocal scanning laser ophthalmoscopy and optic coherent tomography (OCT) are compared. OCT was performed using Stratus OCT 3000 ("Carl Zeiss Meditec"), and for confocal scanning laser ophthalmoscopy we used Heidelberg retinal tomography HRT 3.0 ("Heidelberg Engineering"). A total of 81 patients (158 eyes) were enrolled into the study: 34 patients (64 eyes) with suspected glaucoma (diagnosis of early open angle glaucoma was proven after ophthalmologic examination) and 47 healthy adults aged from 38 till 72 years old. OCT was found to reveal significant decrease of retinal nerve fiber layer (RNFL) thickness in peripapillary zone in patients with suspected glaucoma as compared with healthy subjects, whereas no significant difference in morphometry of neuroretinal rim and PNFL was found using confocal scanning laser ophthalmoscopy (HRT).

[Results of clinical evaluation of a new screening method for determining the individual normal level of intraocular pressure].

The paper presents the results of practical application of a new screening method for determining tolerant intraocular pressure (TIOP) on a Blood Flow Analyzer (Paradigm, USA). Studies were conducted on 331 eyes (205 subjects). Group 1 consisted of 80 patients (126 eyes) without glaucoma being found, with intraocular pressure (IOP) in the average normal range, but with a TIOP excess of 1-8 mm Hg (a risk group); Group 2 included 15 subjects (20 eyes) without glaucoma with normal IOP in whom TIOP exceeded the existing IOP by 1-7 mm Hg; Group 3 comprised 110 patients (185 eyes) with Stage I-III primary open-angle glaucoma (POAG) with compensated IOP. Morphofunctional studies revealed glaucoma in 95 (75%) eyes in the risk group: Stages II and I in 61 and 30%, respectively; and advanced glaucoma in 9%. At the same time, there was a close correlation of the probable detection of glaucoma with the existing degree of a TIOP excess. No cases of glaucoma were observed in Group 2. The determination of TIOP and morphofunctional changes over time in Group 3 revealed a stable glaucomatous process in 99% of cases in which IOP was lower than or equal to TIOP, as well as progressive glaucomatous neuropathy in 91% in which compensated LOP exceeded TIOP. The results of the study in Group 3 suggest that the index TIOP may be used as a guide of IOP in the treatment and monitoring of POAG. The presented data indicate that the determination of the level of TIOP is a required element of both standard ophthalmological examination and monitoring of glaucoma.

[Diagnostic value of macular morphometry in patients with primary open-angle glaucoma].

In this article the results of practical use of central retinal zone (CRZ) tomography in primary open-angle glaucoma (POAG) measured with RTA (Retinal thickness Analyzer, Talia Technology Ltd., Israel) are presented. 460 patients (790 eyes) aged 45-85 years old were included into the study. Significant decrease of CRZ minimal thickness and perifoveal region thickness (p < 0.05 and p = 0.01 respectively) was revealed in patients with POAG compared with control group. Morphometric data showed correlation with decrease of light sensitivity and visual field defects detected with static perimetry. This fact confirms information value of central retinal morphometric changes for glaucoma diagnosis.

[A new screening method for determining tolerant intraocular pressure].

The authors proposed a new screening for determining individual tolerant intraocular pressure (TIOP). The investigation covered 107 individuals (167 eyes). All the examinees were divided into three groups. Groups 1 and 3 comprised healthy volunteers without the signs of vascular changes and glaucoma; Group 2 included patients with new-onset glaucoma with uncompensated intraocular pressure (IOP). There was a regression relationship of ocular blood flow (OBF) to the length of the anteroposterior ocular axis (APOA), which showed a high correlation between OBF and APOA. To determine TIOP, the authors proposed the calculation formula: TIOP = P x K/K(n), where P is the tonometric IOP (mm Hg); K is the flowmetric value of OBF (microl/sec); K(n) is the individual normal OBF value (microl/sec) determined by the nomogram developed by the authors, by taking into account the value of APOA (mm). It is suggested that the eye has a certain buffer range of excessive tolerant pressure within which increased ophthalmotonus results in abnormal sequels. The patients with TIOP that is lower than the existing IOP in the absence of glaucoma symptoms should be classified as a risk-group.

[Morphological rationale for autografting of musculus rectus ocularis fibers at revascular optic nerve decompression surgery].

The authors made a morphological study of the early proposed and clinically tested revascular optic nerve decompression operation developed to improve blood supply to the initial portion of the optic nerve in glaucoma-induced optic neuropathy. An experiment was carried out on 11 rabbits. The operated and control eyes were enucleated 1, 4, and 6 months after surgery. The experiment has established that muscle autografting into the retroscleral and paraneural space of the optic nerve is followed by a number of cellular reactions with the active participation of satellite cells, some of which may be associated with regenerative processes and presumably regarded as one of the cell autotherapy modalities.

[Comparative evaluation of the efficiency of transscleral diode laser cyclophotocoagulation during contact and contactless procedures: experimental morphological study].

To elucidate the extent to which contact and contactless procedures of diode laser transscleral cyclophotocoagulation (CPC) has a antihypertensive effect and a ocular tissue damaging effect, the authors have made a comparative assessment of the procedures to determine their preference. The study was conducted on an experimental material (5 Chinchilla rabbits (10 eyes)). The follow-up was 1 day to 6 months after laser interventions. The authors estimated the parameters of ocular hydrodynamics before and laser intervtntion throughout the follow-up and analyzed them with morphological changes kept in mind. The final antihypertensive effect of both contact and contactless procedures was virtually equal. However, less inflammatory changes and lower ocular damaging effect, and no additional medical manipulations for contactless diode laser CPC make it more preferable to contact CPC for clinical use.

[Determination of individually endurable intraocular pressure (pressure of target) in primary glaucoma]. / K opredeleniiu individual'no-perenosimogo vnutriglaznogo davleniia (daleniia tseli) pri pervichnoi glaukome.

On the basis of ocular perfusion pressure a new method was suggested for determining an individually endurable intraocular pressure (IOP), i.e. pressure of target. A total of 390 eyes (232 patients with primary open-angle and normal-tension glaucoma) were examined before and after conservative and surgical treatment. The pressure of target was found, in a progressing worsening of visual functions, to be significantly lower versus the stabilized glaucoma, which was due to a low ocular perfusion pressure. The maximally tolerable IOP in a progressing glaucomatous optic neuropathy concomitant with a normalized IOP amounts to 13-15 mm Hg; while, in the stabilized glaucoma it can exceed the mean statistic norm. The pressure of target was shown to be a non-permanent value, which changes depending on the dynamics of the ophthalmic perfusion pressure and IOP. The sensitivity of the suggested method is 77.4%. It can be used in prognosticating the glaucomatous-process clinical course and in choosing an optimal tactics for the treatment of open-angle and normal-tension glaucoma.