The efficacy of TonoLab in detecting physiological and pharmacological changes of mouse intraocular pressure--comparison with TonoPen and microneedle manometery.
OBJECTIVE
The efficacy of two non-invasive tonometers, TonoLab and TonoPen XL, in detecting physiological or pharmacological changes of intraocular pressure (IOP) in mouse eyes, was assessed by comparison with a microneedle method.


METHODS
C57BL6 mice, bred under the 12-hr light and dark cycle over 2 weeks, were used. Under systemic anesthesia, mouse eyes were cannulated by a microneedle connected to a transducer and a water reservoir. We manipulated the intracameral pressure by changing the reservoir height, and obtained tonometer readings at each pressure (n=39) with TonoLab and TonoPen XL. The correlation between each tonometer and the manometer was analyzed. Then the diurnal variation of IOP in the light and dark phases, and the IOP-lowering effect at 2 hr after latanoprost instillation, were measured with TonoLab, TonoPen XL, and a microneedle tonometer (n=8).


RESULTS
In mouse eyes, TonoPen XL could not show reliable scores, but TonoLab readings showed a strong correlation with manometer readings (y=0.87x-0.27, r2=0.917). Nocturnal elevation of IOP in mouse eyes was significantly indicated with TonoLab and a microneedle tonometer (p<0.001), but not with TonoPen XL. Latanoprost significantly reduced IOP by 2.1+/-2.8 and 2.0+/-1.0 mmHg with TonoLab and a microneedle tonometer, but not with TonoPen XL.


CONCLUSIONS
TonoLab provides similar readings to a microneedle tonometer, and diurnal variation and drug effect were detectable in mouse eyes. TonoLab promises to be a non-invasive and useful method to evaluate physiological and pharmacological studies in mouse eyes.
Saeki
Tadashiro
T
Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan.
Aihara
Makoto
M
Ohashi
Masaaki
M
Araie
Makoto
M
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D002940:Circadian Rhythm; D003623:Dark Adaptation; D007429:Intraocular Pressure / Q000187:drug effects* / Q000502:physiology*; D000077338:Latanoprost; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology*; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000379:methods*
D000959:Antihypertensive Agents; D011461:Prostaglandins F, Synthetic; D000077338:Latanoprost