Análise elastográfica ocular por compressão mecânica em cães normotensos e com hipertensão arterial sistêmica tratada e não tratada

Abstract

Ultrasonography is a valuable tool in Veterinary Medicine, enabling accurate diagnoses in situations where tissue palpation is impractical. This method is particularly effective in evaluating the canine ocular bulb, where other approaches may be limited. Ocular ultrasound is a non-invasive examination that can be performed without the need for general anesthesia, facilitating its implementation in clinical ophthalmology. To enhance imaging findings, ultrasonography can be complemented with elastography, a technique that provides qualitative and quantitative data about tissues and organs. Although widely used in other areas, its application in veterinary ophthalmology remains scarce. The analysis of tissue elasticity in vivo can be performed using mechanical compression methods and shear wave techniques, resulting in elastograms that indicate the degree of resistance of the tissue to mechanical stimuli. Systemic arterial hypertension is a comorbidity that can cause severe damage in dogs, with the eyes frequently presenting the first clinical signs. The most common ocular lesions include retinal blood vessel tortuosity, focal retinal edema, and retinal hemorrhage. As the disease progresses, retinal detachment and intravitreal hemorrhage may occur, resulting from initial arteriolar vasoconstriction and vascular ischemia. This study revealed significant differences in systemic arterial pressure (SAP) among normotensive dogs, treated hypertensive dogs, and untreated hypertensive dogs, with averages of 131 mmHg, 181 mmHg, and 207 mmHg, respectively. The untreated hypertensive group showed the highest arterial pressure, with a statistically significant difference (P = 0.0058). However, when evaluating intraocular pressure (IOP), no significant differences were observed among the groups: in the left eye (LE), the averages were 15 mmHg (normotensive), 16 mmHg (treated hypertensive), and 16 mmHg (untreated hypertensive) (P = 0.9154). In the right eye (RE), the values were 18 mmHg (normotensive), 17 mmHg (treated hypertensive), and 17 mmHg (untreated hypertensive) (P = 0.9328). Additionally, the pulsatility index (PI) and resistivity index (RI) in the ophthalmic artery also showed no significant differences. In the LE, the PI was 0.72 (normotensive), 0.94 (treated hypertensive), and 0.78 (untreated hypertensive) (P = 0.3577). The RI varied between 0.54, 0.62, and 0.53, respectively (P = 0.1668). In the RE, the PI was 0.72, 0.88, and 0.90 (P = 0.2197), while the RI was 0.50, 0.58, and 0.59 (P = 0.1258). In summary, despite the differences in SAP among the groups, no significant variations were noted in ocular vascular resistance parameters or in other elastographic indices. The research highlighted the effectiveness of ocular ultrasonography and the relevance of antihypertensive drugs, even without statistically significant correlations with elastographic measurements. The scarcity of studies on elastography in hypertensive dogs underscores the importance of this work in stimulating further investigations into hypertension and its consequences for canine ocular health.