隱型眼鏡裝用對於眼睛的影響　第一篇　隱型眼鏡裝用對於角膜知覺的影響（附自作電氣角膜知覺計）

The Influence of the Contact Lens Wear on the Eye Part 1, the Influence of the Contact Lens Wear on the Corneal Sensitivity (With Self-Deviced Electro-Micro-Stimulator)

柯良時(Liang-Shi Ko)

《中華民國眼科醫學會會刊》 11卷 (1972/05) Pp. 22-38

https://doi.org/10.30048/ACTASOS.197205.0003

並列摘要

In 1963, the author and Tomiyama already made a preliminary report of the influence of the contact lens application on the corneal sensitivity. We found that all of the four patients who had worn the sphercon contact lens more than three years and had superficial punctuate keratopathy showed an evident decrease of corneal sensitivity immediately after taking off the contact lens and gradually recovered almost to their normal level within twenty minutes later. However, except the brief report presented by Drs. Kakiuchi and Kemmetmueller, no systemic study have been carried out on how corneal sensitivity would change after the long-term application of the contact lens ever since. In view of the fact that this problem is still remained unsolved, the author has continued to measure corneal sensitivity of two groups using the self-deviced electro-micro-stinulator: One consists of several Chinese with healthy cornea and the other with wearing the contact lens for a considerable period of time.
The machine modified and deviced by the author is more compact, portable and less expensive. First of all, the accuracy of the machine was tested and determined by measuring corneal sensitivity of ten normal persons, five times respectivelly at the fixed time for five consecutive five-days (Table Ⅰ). Afterwards, corneal sensitivity was measured on other ten normal persons respectivelly at the four different times during a day. This is done also for the purpose of observing whether or not corneal sensitivity will show any diurnal variation, same as intraocular pressure does (the table Ⅱ). Furthermore three doctors were selected to measure respectivelly corneal sensitivity of a group of three other persons (The table Ⅲ) The results of the above various tests have proved that the author's machine is fairly accurate and easy to operate. It was also noted that there was no evident diurnal variation on corneal sensitivity in this study (The table Ⅱ).
Therefore, the author thinks that it is not necessary to measure corneal sensitivity at the fixed time in a day.
Next to this, thirty normal young Chinese and twenty normal aged Chinese were selected for measurement of their corneal sensitivity in the same way. The results showed that there was a great individual variation both in the young chinese group and the aged group. In general, the corneal sensitivity in the young group is more sensitive than in the aged group (the table 4 & 5). Based on these findings, the author wishes to emphasize that in the comparison of the corneal sensitivity of the two groups, the individual variation and the age factor should be considered carefully before drawing any conclusion, and that it is considered to be a better method to trace the change of the corneal sensitivity of the same persons for the discussion of the corneal sensitivity. Finally, the corneal sensitivity of the contact lens long-term wearers was studied. Twenty persons who had worn the contact lens more than three years were measured on their corneal sensitivity immediately after taking off the contact lens, and five minutes, ten minutes. fifteen minutes, twenty minutes, twenty-five minutes and thirty minutes after removing the lens respectivelly. The results showed that in the majority of the caeses, their corneal sensitivity evidently decreased at the time of the removal of their lenses, and nearly recovered to their normal level within thirty minutes. This finding supports our conclusion in the previous paper. However, the response to the contact lens wear seems to be more complicated than what was suspected before. That is, in some patients, though they had relativelly evident corneal erosion, no definite decrease of the corneal sensitivity was found. On the other hand, in some patient, who had relativelly less evident corneal change, a definite decrease of the corneal sensitivity was detected. These results suggest that the individual variation in response to the contact lens wear also seems to be evident, and corneal erosion, at least in some cases, seems to have little relation to the decrease of corneal sensitivity. When one contact lens was removed, five out of the all ten cases showed that the corneal sensitivity in both eyes nearly recovered to their normal level, even though they were still wearing the contact lens in the other eye. However, the remaining half of the all ten cases showed a definite (but less evident) decrease of the corneal sensitivity in the eye where the contact lens was still on. This indicates the mechanism f suppression of corneal sensitivity due to the contact lens wear seems to be considerably complicated and the response to the contact lens wear appears to be varied due to individuals. It is still difficult to draw any conclusions at the present time whether the decrease of corneal sensitivity due to the contact lens wear is caused by a central inhibition or by a peripheral inhibition. Further studies should be made to explore this problem.

The machine modified and deviced by the author is more compact, portable and less expensive. First of all, the accuracy of the machine was tested and determined by measuring corneal sensitivity of ten normal persons, five times respectivelly at the fixed time for five consecutive five-days (Table Ⅰ). Afterwards, corneal sensitivity was measured on other ten normal persons respectivelly at the four different times during a day. This is done also for the purpose of observing whether or not corneal sensitivity will show any diurnal variation, same as intraocular pressure does (the table Ⅱ). Furthermore three doctors were selected to measure respectivelly corneal sensitivity of a group of three other persons (The table Ⅲ) The results of the above various tests have proved that the author's machine is fairly accurate and easy to operate. It was also noted that there was no evident diurnal variation on corneal sensitivity in this study (The table Ⅱ).
Therefore, the author thinks that it is not necessary to measure corneal sensitivity at the fixed time in a day.
Next to this, thirty normal young Chinese and twenty normal aged Chinese were selected for measurement of their corneal sensitivity in the same way. The results showed that there was a great individual variation both in the young chinese group and the aged group. In general, the corneal sensitivity in the young group is more sensitive than in the aged group (the table 4 & 5). Based on these findings, the author wishes to emphasize that in the comparison of the corneal sensitivity of the two groups, the individual variation and the age factor should be considered carefully before drawing any conclusion, and that it is considered to be a better method to trace the change of the corneal sensitivity of the same persons for the discussion of the corneal sensitivity. Finally, the corneal sensitivity of the contact lens long-term wearers was studied. Twenty persons who had worn the contact lens more than three years were measured on their corneal sensitivity immediately after taking off the contact lens, and five minutes, ten minutes. fifteen minutes, twenty minutes, twenty-five minutes and thirty minutes after removing the lens respectivelly. The results showed that in the majority of the caeses, their corneal sensitivity evidently decreased at the time of the removal of their lenses, and nearly recovered to their normal level within thirty minutes. This finding supports our conclusion in the previous paper. However, the response to the contact lens wear seems to be more complicated than what was suspected before. That is, in some patients, though they had relativelly evident corneal erosion, no definite decrease of the corneal sensitivity was found. On the other hand, in some patient, who had relativelly less evident corneal change, a definite decrease of the corneal sensitivity was detected. These results suggest that the individual variation in response to the contact lens wear also seems to be evident, and corneal erosion, at least in some cases, seems to have little relation to the decrease of corneal sensitivity. When one contact lens was removed, five out of the all ten cases showed that the corneal sensitivity in both eyes nearly recovered to their normal level, even though they were still wearing the contact lens in the other eye. However, the remaining half of the all ten cases showed a definite (but less evident) decrease of the corneal sensitivity in the eye where the contact lens was still on. This indicates the mechanism f suppression of corneal sensitivity due to the contact lens wear seems to be considerably complicated and the response to the contact lens wear appears to be varied due to individuals. It is still difficult to draw any conclusions at the present time whether the decrease of corneal sensitivity due to the contact lens wear is caused by a central inhibition or by a peripheral inhibition. Further studies should be made to explore this problem.