VAMPIRE^® fundus image analysis algorithms: Validation and diagnostic relevance in hypertensive cats

Abstract

Objectives To validate a retinal imaging software named VAMPIRE® (Vascular Assay and Measurement Platform for Images of the Retina) in feline patients and test the clinical utility in hypertensive cats. Animals studied One hundred and five healthy cats were enrolled. They represented the normal dataset used in the validation (group 1). Forty‐three hypertensive cats with no noticeable retinal abnormalities were enrolled for the clinical validity of the software (group 2). Procedures Eleven points (4 veins, 4 arteries, and 3 arterial bifurcations) were measured for each digital image. Repeatability and reproducibility of measurements were assessed using two independent operators. Data were statistically analyzed by the Mann‐Whiney and Tukey box plot. Significance was considered when P < 0.05. Results Two hundred and ten retinal images were analyzed for a total of 2310 measurements. Total mean was 9.1 and 6.1 pixels for veins and arteries, respectively. First, second, and third arteriolar bifurcations angles were 73.6°, 76.9°, and 85.4°, respectively. A comparison between groups 1 and 2 showed a statistically significant reduction in arteriolar diameter (mean 3.3 pixels) and branch angle (55°, 47.8° and 59.9°) associated with increasing vein diameter (mean 24.15 pixels). Conclusions Current image analysis techniques used in human medicine were investigated in terms of extending their use to veterinary medicine. The VAMPIRE® algorithm proved useful for an objective diagnosis of retinal vasculature changes secondary to systemic hypertension in cats, and could be an additional diagnostic test for feline systemic hypertension.

Ocular fundus abnormalities in cats affected by systemic hypertension: Prevalence, characterization, and outcome of treatment

“…The veterinary literature reports that long‐term maintenance of vision is difficult to achieve in feline patients with ocular TOD due to SHP because of secondary retinal degeneration. The duration of retinal detachment is thus a critical factor: the shorter the period of detachment, the better the prognosis for the restoration and maintenance of visual function 19,24,25 . A limit of our study is the impossibility to establish the real duration of retinal detachment.…”

“…In the population we examined, 21.4% of the cats with ophthalmoscopic abnormalities showed mild lesions (grade 1). This reflects the importance of both a clinical and computer‐assisted 25 fundus examination, even in hypertensive cats that do not show any visual impairment. The results of color fundus images processing using Vampire ® algorithm in cats classified as grade 0 (no noticeable fundus abnormalities, but clinically diagnosed with SHP) demonstrated the potential role of the retinal image analysis in the early diagnosis of hypertensive retinopathy.…”

“…The results of color fundus images processing using Vampire ® algorithm in cats classified as grade 0 (no noticeable fundus abnormalities, but clinically diagnosed with SHP) demonstrated the potential role of the retinal image analysis in the early diagnosis of hypertensive retinopathy. The Vampire ® algorithm used to measure vascular diameters and angles of arterial bifurcations contributed to the objective diagnosis of early damage to the ocular fundus as a result of SHP 25 …”

“…For the fundus photographic documentation, a digital fundus camera for veterinary use (Clearview, Optibrand LLc, Ft Collins, Columbia, United States) was employed. Vampire ® (Vascular Assay and Measurement Platform for Images of the Retina) software modified for the feline fundus was used for image processing in 35 cats from the grade 0 group (no noticeable fundus abnormalities but clinically diagnosed with SHP) 25 …”

“…Thus to date, the real prevalence of ocular fundus abnormalities in cats with SHP has not been well characterized. Although there are a number of studies on the effect of blood pressure on the animal eye, little information is available on the characterization of ocular fundus abnormalities and outcome after starting antihypertensive medical therapy 9,20,21,23,25 …”