Tonopen

Tonopen 

A handheld, compact, portable applanation tonometer based on the same principle as the Mackay-Marg tonometer. It is a very small instrument, 18 cm long by 2 cm in width weighing 56 g. It incorporates its own battery power supply and liquid crystal digital readout and provides both an intraocular pressure readout and an indicator of the reliability of the instrument. The results correlate well with the Goldmann tonometer, although it slightly overestimates low IOPs and underestimates high IOPs. It can take measurements in an eye with an irregular or oedematous cornea or through a soft contact lens and in a variety of clinical settings (Fig. T17). See applanation tonometer.
Fig. T17 Tonopenenlarge picture
Fig. T17 Tonopen
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References in periodicals archive ?
The most commonly used tonometers are the TonoPen XL (Reichart; Depew, NY, USA; applanation tonometer) and the TonoVet (Icare; Tiolat, Helsinki, Finland; rebound tonometer).
Measurement of the difference in intraocular pressure between the sitting and lying body positions in healthy subjects: direct comparison of the Icare Pro with the Goldmann applanation tonometer, Pneumatonometer and Tonopen XL.
Comparison of the rebound tonometer (TonoVet[R]) with the applanation tonometer (TonoPen XL[R]) in normal eurasian eagle owls (Bubo bubo)" Veterinary Ophthalmology, v.10, n.6, p.376-79, 2007.
Ocular examinations included evaluation of Snellen best spectacle corrected visual acuity (BCVA), biomicroscopy of the anterior segment, intraocular pressure (IOP) measurement with Goldmann applanation tonometer or Tonopen, and fundus examination.
Tonopen is a popular applanation tonometer based on the Mackay-Marg principle.
From existing tonometers only the TonoPen combines these capabilities and above all, it is a standard reference instrument widely used by ophthalmologists.
Nowadays, several methods of IOP measurement have been developed for clinical use, including the gold-standard Goldmann applanation tonometer (GAT), the dynamic contour tonometer (DCT), TonoPen, and Icare rebound tonometer.
The efficacy of TonoLab in detecting physiological and pharmacological changes of mouse intraocular pressure – Comparison with TonoPen and microneedle manometery.
A TonoPen XL (Mentor, USA) tonometer was used to assess IOP in conscious, non-sedated rats as described previously (22).
Goldmann applanation tonometry (GAT), the gold-standard method for the measurement of IOP, and related techniques such as NCT and TonoPen, use the Imbert-Fick principle to determine this value.
Heuer et al., "Clinical evaluation of the Oculab Tonopen," American Journal of Ophthalmology, vol.
Tonopen XL assessment of intraocular pressure through silicone hydrogel contact lenses.