The pupil of a lens is an image of the aperture stop. The entrance pupil of a lens or lens system is the image of the aperture stop as seen from the object space. The exit pupil, however, is the image of the aperture stop as seen from the image space. In other words, the entrance pupil, the aperture stop and the exit pupil are conjugate planes.  In combining a microscope objective and a relay lens, the aperture stop of the microscope objective and that of the relay lens must be conjugate planes. It is important that the exit pupil of the microscope objective and the entrance pupil of the relay lens are conjugate planes. If not so, the image intensity will suddenly decrease at the edge of the field. As a solution to this, a field lens is inserted between the objective and the relay lens. For the same reason it is desirable that the pupil of the image sensor is coincident with the exit pupil of a lens system.  Spherical aberration of the pupil causes formation of a shadow at the edge of the field. The shadow moves about in the field as the eye is moved. Longitudinal chromatic aberration of the pupil causes image color difference between the field center and field edge. The image color in some parts of the field changes as the eye is moved.

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Purpose: To study the rate of use of 0.01% atropine sulfate ophthalmic solution (atropine 0.01%) and the one-year rate of myopia progression in patients for whom atropine 0.01% was prescribed continuously for at least three years.  Methods: This study was conducted on 40 eyes (20 patients) for which atropine 0.01% was prescribed continuously for at least three years. Mean observation term was 5.0±1.4 years. Rate of atropine 0.01% usage was defined as the value obtained when the number of prescriptions for atropine 0.01% was dived by the period of observation. Subjects were divided based on that rate of usage, namely, those with a rate of at least 0.5 (high rate of atropine usage group) and those with a rate below 0.5 (low rate of atropine usage group). The respective one-year myopia progression of the groups was compared.   Result: The high rate of atropine usage group consisted of 16 eyes (8 patients); the low rate of atropine usage group consisted of 24 eyes (12 patients). Mean one-year myopia progression was -0.64±0.15D in the high rate of atropine usage group and -0.58±0.29D in the low rate of atropine usage group, however, there was no significant difference (t-test, p<0.05).  Conclusion: A rate of atropine usage of at least 3 years long-term, possibly has no effect on myopia progression.

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