| Fluorescein Penetration to Human and Rabbit Eyes. |
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Jae Ho Kim, Yoichi Ota |
1Department of Ophthalmology, Catholic Medical College, Seoul Korea.
2Department of Ophthalmology, School of Medicine Universtity of Tokyo, Japan. |
| 사람과 토끼 눈에서의 후로레스친 투과 |
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김재호 , 태전양일 (太田陽一) ( Jae Ho Kim , Yoichi Ota ) |
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| Abstract |
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Drug penetration studies have been conducted in almost all cases, using the rabbits. Unless we know difference all similarity between human and rabbit eyes, extrapolation of rabbit data to human eyes is very difficult. With use of fluorescein which can be determined in the living eyes, mode of intraocular penetration following topical application was studied in human and rabbit eyes with particular emphasis on difference between two specieses. In human eyes, fluorescein penetration was less-done since application of ten times more concentratied solution was required to achieve comparable anterior chamber concentrations as in rabbit. Rabbit blinks rarely and it allows flourescein to stay in the precorneal tear film and meniscus for long time thereby making more fluorescein available for penetration across the cornea. In order to study the effect of fluorescein turnover in the tear film on intraocular pentration, rabbit were divide into two groups where conjunctival sac was washed and unwashed after fluorescein instillation. In the group without conjunctival washing, the anterior chamber concentration was higher and the peak time was more delayed up to 2 hours and 30 minutes while the peak times of human and rabbit with washing group were approximately 2 hours. Corneal concentration of fluorescein could be determined initially in 1 hour and 30 minutes after instillation and then gradual decrease of the concentration which keeps paralled with the concentration curve of aqueous humour with time. Difference in the degree of intraocular penetration between human and rabbit may be attributed the fact that epithelial defect is always found in almost all normal rabbit corneas, where is, in human corneas epithelial defect is not found in normal cornea. It is thus pointed out that difference in intraocular drug penetration may exist between two specieses and extrapolation of rabbit data to human eyes must be made with caution. |
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