Biometric, B-mode and color Doppler ultrasound assessment of eyes in healthy dogs

Abstract

B-scan ultrasonography is an important diagnostic tool that allows characterization of internal organ anatomy and, when complemented by Doppler ultrasound, allows vascular hemodynamic assessment, increasing the diagnostic accuracy. Thus, the aim of the present study was the B-scan ultrasound characterization and measurement of the eyeball segments and assessment of the external ophthalmic artery by color and pulsed Doppler. Sixty eyeballs were assessed from 30 dogs of different breeds using an 8.5MHz microconvex transductor. First, biometry was performed by B-scan of the following segments: axial length (M1), anterior chamber depth (M2), lens thickness (M3), lens length (M4), vitreous chamber depth (M5), optical disc length (M6) and optic nerve diameter (M7). Colored Doppler identified the external ophthalmic article and pulsed Doppler assessed its flow, and the following were measured: systolic peak velocity (VPS), final diastolic velocity (VDF), resistivity index (IR) and pulse index (IP). No statistical difference was observed for the biometric values of the eye segments between the right and left eyes (p>0.05). The vitreous chamber depth (M5) was shown to be the biometric variable with greatest bilateral symmetry, varying from 0.79 to 0.87cm and 0.78 to 0.86cm for the right and left eye, respectively. The ophthalmic artery was visualized over the optic nerve towards the eyeball, with flow stained red. There was no significant statistical difference between the Doppler velocimetric values for the ophthalmic artery between the right and left eye of the animals assessed (p>0.05). The mean resistivity index (RI) showed average values equal to 0.63±0.03, bilaterally. The mean base velocity was 17.50cm/s and 18.18cm/s at the systolic peak and 6.21cm/s and 6.68cm/s at the end of the diastole, for the right and left eyes respectively. The anatomic, biometric and hemodynamic characterization using the ultrasound B-scan and the Doppler modalities permitted the ultrasonographic and Doppler velocimetric assessment of the eyeball components in dogs of different breeds, and it can be used in ophthalmic clinical routine to identify eye pathologies.

Ocular Echobiometry and Resistivity Index of External Ophthalmic Artery in Agoutis (Dasyprocta prymnolopha)

“…The anterior chamber thickness values in this experiment did not differ statistically between the antimers. Similarly, when determining the ophthalmic parameters in dogs, did not observe statistical difference in this evaluation and found on average similar values to those described in this study [14].…”

“…The sonographic characteristics of the agouti eye are like those described in the literature in other domestic and wild animal species [1,2,3,6,8,11,14,16,18]. The correlation between the lens and the axial length of the eyeballs in the agouti was 1: 1.5, lower than that described in other rodent species such as chinchillas (1:2), guinea pig (1:2), and rats (1:2,6), giving them the anatomical characteristic of small eyes and a large lens [2,6,8].…”

“…B-mode ultrasound is a useful resource in veterinary medicine and has gained importance. It is a fast and safe technique that provides important and complementary information to the ophthalmic examination, as well as a qualitative and quantitative evaluation of intraocular and orbital lesions [14]. This feature, when applied to wild animals, is particularly important in the diagnosis of ophthalmic pathological changes and determination of normal biometric values [18].…”

Semiología oftálmica veterinaria: Revisión

“…Além disso, de acordo com Silva et al (2018), existe a ultrassonografia em modo-B por meio de Doppler colorido, sendo uma técnica recente e que não necessita de sedação ou anestesia, aprimorando assim o diagnóstico. Com ela é possível a visibilização do globo ocular, verificando a artéria oftálmica externa.…”