Trial Lens Set
The curved surface forms a part of the spherical lens and the diopric power onalll axis positions is the same. After passing the lens, the light beam focusesin one point ( or a virtual focus ). Spherical lens includes concave lens ( - )and convex lens ( + ) which are used to examine myopia, hyperopia andpresbyopia.
The curved surface forms a part of cylindrical lens and the dipodic power onall axis positions is not the same. After passing the lens, the light beamfocuses into a straight line ( or a broken line ). Cylindrical lens consists ofconcave cylindrical lens and convex cylindrical lens that are used to examineastigmatism.
The tangent plain of prismatic lens shows cuneiform. After passing the lens,the light beam bends to the bottom and the object shifts to edges. This kind oflens is used to test eye-flesh, slant and invisible slant as well as to traineye-flesh.
This is a kind of opaque lens for covering the uninspected eye of the examineein a dark room.
This is a kind of semi transparent cover lens and mainly used for babies orused outside of the room as anoccluder
In its center, there is a split, through whish light beam can psaa while itcannot pass the other part of the lens. By turning this lens in front of theeye, astigmatism can be examined as your vision changes in better or in worseat a certain axis position, on the contrary, it proves no existence ofastigmatism if your vision has change.
This is a kind of transparent plain lens and the light beam never bends when itpasses the lens. It is used to examine false blindness.
This kind of lens has different colors, red, green, blue, yellow and dark brownand is used to examine color sensitivity. To such person whose dipodic image ismuddy ( e. G a patient with cataract ), the red or green lens is suitable, italso can be used for re-inspection and examination of color blindness.
This is a kind of lens with contrary dipodic in two axis positions and used toexamine the degree and axis position of the cylindrical lens for determiningastigmatism. When using, put the cross cylindrical lens, before cylindricallens, and make its one axis coincide with the axis position of cylindrical lensthen turn the cross cylinder lens 90 * counter-clockwise and see the change ofvision if his vision has no change the degree of cylindrical lens used can beconsidered as suitable, otherwise the degree of cylindrical lens would becylindrical lens would be adjusted according to the variant results. Incorrecting the axis position, respectively out the two axes of cross cylinderlens at the right side ( 45* ) and the left side ( 45 * ) of primary test axisof cylindrical lens, then turn it counter clockwise and see differencesof vision at two positions. If vision on one position is better than that onanother position, the axis of cylindrical lens can be slightly turned in thedirection of position mark of the better one, then test again by the usedabove, until difference of vision at two positions can hardly be distinguished,thus proving that the cylindrical lens is the correct position.
On its surface, there is one row of bars which point light can pass, and thenbends into a line to the direction, which is perpendicular to the glass bars.
In its center, there is a small hole, through which light beam passes to formartificial pupil and it is used to improve diopter especially the astigmatismafter wearing it.