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Clinical comparison of the T ono V et ® rebound tonometer and the T ono‐ P en V et ® applanation tonometer in dogs and cats with ocular disease: glaucoma or corneal pathology
Author(s) -
Spiessen Lena,
Karck Julia,
Rohn Karl,
MeyerLindenberg Andrea
Publication year - 2015
Publication title -
veterinary ophthalmology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.594
H-Index - 50
eISSN - 1463-5224
pISSN - 1463-5216
DOI - 10.1111/vop.12101
Subject(s) - ophthalmology , glaucoma , intraocular pressure , cornea , medicine , ophthalmic pathology , neuro ophthalmology
Objective To compare the T ono V et ® rebound tonometer with the T ono‐ P en V et ® applanation tonometer in a larger number of glaucomatous eyes and to evaluate the effect of different corneal pathologies on both tonometers. Procedure In 26 eyes with clinical signs of glaucoma, intraocular pressure ( IOP ) was measured using the T ono V et ® followed by the T ono‐ P en V et ® . In 29 eyes with focal corneal pathology (e.g., corneal scarring, edema, pigmentation), both tonometers were used successively to measure IOP in one unaffected area of the cornea, as well as on the lesion itself. Impact on measurement results was assessed comparing the deviation in IOP readings of each tonometer between the two localizations. Statistical data analysis included paired t ‐tests and regression analysis using sas software (version 9.2; SAS I nstitute, C ary, NC ). Results In glaucomatous eyes, the T ono V et ® consistently yielded higher values of IOP than the T ono‐ P en V et ® as can be quantified by the regression equation IOP ( T ono V et ® ) [mmHg] = 1.12 * IOP ( T ono‐ P en V et ® ) [mmHg] + 11.5 with R 2 = 0.91 and P < 0.0001. Depending on the type and degree of corneal pathology, the deviation in IOP resulting from measurements on altered cornea ranged from −6 to 16 mmHg for the T ono V et ® and −7 to 20 mmHg for the T ono‐ P en V et ® , respectively. On average, the effect of corneal disease on IOP measurements was lower for the T ono V et ® by 1.14 mmHg. Conclusions Rebound tonometry appears to be a valuable alternative to established applanation tonometry in patients with ocular disease such as glaucoma and corneal disorders. In patients suffering from glaucoma, the same type of tonometer should be used for follow‐up examinations, as measurement results of the T ono V et ® and the T ono‐ P en V et ® differ substantially with increasing IOP . Corneal pathology has considerable influence on both tonometers with the degree of over‐ or underestimation of IOP depending on the alteration of biomechanical properties of the cornea inflicted by various corneal pathologies.