[Effects of pirenzepine on lens-induced myopia in the guinea-pig].
OBJECTIVE
To determine the efficacy of the M(1)-selective muscarinic antagonist, pirenzepine, in preventing lens-induced myopia in the guinea-pig and to study the mechanism and the possibility of treatment of myopia with pirenzepine.


METHODS
Fifteen 4-week-old guinea-pigs were monocularly fitted with -10.00 D lenses for a period of 11 days. In Group I (n = 7), both eyes received topical administration of 0.24% saline vehicle as the controls. In Group II (n = 8), the lens-fitted eyes were topically treated with 10% pirenzepine, while the other eyes received the vehicle control. Ocular refraction and biometric measurements were collected on the first and the 11th days. All eyes were finally enucleated for histopathological examination to evaluate the possible toxic effects of pirenzepine.


RESULTS
In Group I, 11 days of lens-fitting produced -2.45 D myopia (t = 3.141, P < 0.05) with 0.05 mm elongation of axial dimension (t = 2.500, P < 0.05) as compared to the contralateral eyes. There were no significantly differences of refractive error and axial dimensions between the experimental eyes and the controls in Group II. Histological examinations revealed no obviously toxic effects in the pirenzepine-treated eyes.


CONCLUSIONS
Topical administration of the M(1)-selective muscarinic antagonist, pirenzepine, prevents lens-induced experimental myopia in guinea-pig by inhibiting the elongation of axial dimension with no obvious damage to the ocular tissues.
Ouyang
Chao-hu
CH
Department of Ophthalmology, Eye & ENT Hospital of Fudan University, Shanghai 200031. ly001301@online.sh.cn
Chu
Ren-yuan
RY
Hu
Wen-zheng
WZ
D000818:Animals; D003261:Contact Lenses / Q000009:adverse effects*; D004195:Disease Models, Animal; D006168:Guinea Pigs; D018727:Muscarinic Antagonists / Q000627:therapeutic use; D009216:Myopia / Q000209:etiology / Q000517:prevention & control*; D010890:Pirenzepine / Q000627:therapeutic use*
D018727:Muscarinic Antagonists; D010890:Pirenzepine