Ocular echobiometry and resistivity Index of external ophthalmic artery in agoutis (Dasyprocta prymnolopha)

Veterinary Ophthalmology provides complementary information for the diagnosis of ocular pathologies. Studies in wild species are essential. Among the diagnostic techniques in ophthalmology, two-dimensional ultrasonography stands out. The agouti is a rodent belonging to the Dasyproctidae family that has been widely used as an experimental model. For these animals, sight is one of the crucial senses for their survival. The aim of this study was to evaluate the effectiveness of the two-dimensional ocular ultrasound technique to obtain anatomical measurements and the external ophthalmic artery resistivity index, presumably normal in the species Dasyprocta prymnolopha. Forty eye bulbs of 20 adult rodents of the species were evaluated by ultrasonography. In these animals, B-mode echobiometry was performed using the transpalpebral approach and the hemodynamic study of the external ophthalmic artery using the color Doppler technique. All examinations were initiated by the left eye bulb and all measurements were performed by only one examiner. The collected data related to echobiometry were analyzed using Bioest 5.0 for Windows. Initially, normality was tested using the Shapiro-Wilk test for each parameter, then the paired t-test was performed, comparing right and left eyes, and a significance level of 5% (P < 0.05) was adopted. Based on the methodology used, the following values were obtained for the right and left eyeballs, respectively: anterior chamber thickness - mean of 1.28 ± 0.3 mm and 1.22 ± 0.1 mm; lens thickness - 8.27 ± 0.9 mm and 8.11 ± 0.9 mm; vitreous chamber thickness - 5.35 ± 0.48 mm and 5.30 ± 0.47 mm and axial length - 12.7 ± 0.9 mm and 13 ± 0.68 mm. The mean external ophthalmic artery resistivity values were 0.4305 ± 0.0390 and 0.4258 ± 0.0387 (right and left eye, respectively), characterizing a low resistance. There was no statistical difference between the right and left eyeballs in any of the studied parameters. The use of the convex transducer was feasible, promoting adequate contact with the ocular surface and images of satisfactory quality for obtaining measurements, similar to what was observed in studies evaluating the ocular biometry of primates and dogs. The anterior chamber thickness values in this experiment did not differ statistically between the antimers, as well as observed for dogs. The data obtained for lens thickness did not differ statistically for antimers, like those obtained for other rodent species evaluated with the same methodology. The mean values of vitreous chamber thickness were like those observed in chinchillas but correspond to about half of that obtained for capybaras. In this study, the external ophthalmic artery was characterized in all animals, but obtaining the spectral tracing was difficult due to its fine caliber. In wild animals, and especially in wild rodents, there are few data reporting the resistivity of the ophthalmic artery, and there is a lack of studies, which can be explained by the behavioral characteristics of defense and by the high susceptibility to stress in capture, since the performing the technique requires, as in other procedures, the use of chemical containment. (AU)

Valores ecobiométricos e índice de resistividade da artéria oftálmica externa em catetos (Tayassu tajacu, Linnaeus, 1758) / [Ecobiometric values and resistivity index of the external ophthalmic artery in collared peccaries (Tayassu tajacu Linnaeus, 1758)]

Foram avaliados ultrassonograficamente, pela via transpalpebral, 28 bulbos oculares de 14 catetos adultos, através de técnica padronizada pelo operador. Adicionalmente foi realizado o estudo hemodinâmico da artéria oftálmica externa pela técnica de Doppler colorido. Os dados coletados foram analisados estatisticamente pelo programa Bioestat 5.0 for Windows, adotando-se 5% de significância. Com a metodologia empregada, obtiveram-se os seguintes valores para os globos oculares direito e esquerdo, respectivamente D1: 1,72 ± 0,29mm e 1,76 ± 0,40mm; D2: 9,95 ± 1,08mm e 10,6 ± 0,99mm; D3: 7,42 ± 0,93mm e 7,45 ± 0,72mm e D4: 17,6 ± 0,78mm e 17,8 ± 0,59mm. Os valores médios do índice de resistividade da artéria oftálmica externa foram 0,435 ± 0,02 e 0,448 ± 0,02 (globos oculares direito e esquerdo, respectivamente). Não houve diferença estatística quanto aos antímeros oculares em nenhum dos parâmetros estudados. Conclui-se que a ecobiometria ocular e a Dopplerfluxometria da artéria oftálmica na espécie Tayassu tajacu é executável e reprodutível, desde que haja domínio do examinador em relação à anatomia e à técnica adequada. Os valores inferidos neste estudo servem de referência para médicos veterinários no diagnóstico de doenças oculares.(AU)

Twenty-eight ocular bulbs of fourteen adult catheters were evaluated through ultrasound with the transpalpebral approach, using a standardized technique by the operator. Additionally, the hemodynamic study of the external ophthalmic artery was performed using the color Doppler technique. The collected data were statistically analyzed by the Bioestat 5.0 for Windows program, adopting 5% of significance. With the methodology employed, the following values were obtained for the right and left eyeballs, respectively D1: 1.72 ± 0.29mm and 1.76 ± 0.40mm; D2: 9.95 ± 1.08mm and 10.6 ± 0.99mm; D3: 7.42 ± 0.93mm and 7.45 ± 0.72mm and D4: 17.6 ± 0.78mm and 17.8 ± 0.59mm. The mean resistivity index values of the external ophthalmic artery were 0.435 ± 0.02 and 0.448 ± 0.02 (right and left eyeball respectively). There was no statistical difference regarding ocular antimers in any of the studied parameters. We concluded that ocular echobiometry and ophthalmic artery Doppler flowmetry in Tayassu tajacu species is executable and reproducible, provided there is an examiner's domain regarding the anatomy and proper technique. The values inferred in this study serve as a reference for veterinarians in the diagnosis of eye diseases.(AU)