Comparison between the rebound (TD - 8000 portable) and applanation tonometer (Tono-Pen Avia™) managed by different evaluators for intraocular pressure measurements in rabbits

Abstract

This study aimed to compare values of intraocular pressure (IOP) by different tonometers and evaluators (veterinary ophthalmologist specialist and veterinary not a specialist). For this, 30 rabbits were used, and in all (n = 60 eyes), the IOP was initially measured with a rebound tonometer (model TD - 8000 portable, Apramed Indústria e Comércio de Equipamentos Médicos Ltda) and, subsequently, with an applanation tonometer (portable model Tono-Pen Avia™®, Reichert Technologies®, USA). With the two devices, the measurements in mmHg were performed in the central region of the corneas, always performed in the same period, by a professional veterinary ophthalmologist (specialist) and a professional veterinary (not a specialist). Data were statistically compared using the simple analysis of variance test. With the rebound tonometer, IOP ranged from 7 to 14 mmHg when measured by both evaluators; while with the applanation tonometer, from 9 to 15 mmHg by the specialist and from 8 to 16 mmHg by the non-specialist. In the right eyes, the IOP measured by the applanation tonometer by the non-experienced evaluator was statistically lower than the specialist's values; yet, the results of the two evaluators were higher in these same eyes when compared with those of the rebound tonometer. In the left eyes, the IOP measured by the applanation tonometer by the non-experienced evaluator was statistically higher than the specialist's values with the rebound tonometer. Thus, it was possible to infer that, regardless of experience in the area, the applanation tonometer indicated higher mean values of IOP in both eyes and, about the evaluators, the means of the measurements performed by the specialist were higher compared to the non-professional specialist. Keywords: aqueous humor; glaucoma; veterinary ophthalmology; tonometry; uveitis