Evalution Examples of Contact Lenses
Observation of pigments distribution in color contact lenses, observation of edge shape of contact lenses(cross section) :Fig.1
Using microscope, we can observe the cross section of swollen state soft contact lenses in physiological saline.
Fig.2 shows expansion of part A and B of Fig.1. Distribution and presence of pigments can be observed. In this example, the pigments are presented about 100µm thickness at the side of eyelid. We perform size measurement of outer and inner diameter of colored part, and leachable materials test.
Microscopic observation of edge part
Fig.3 shows expansion of part C of Fig.1. The edge shape affects irritation to cornea and movement characteristics in eyes, it is important to control the edge shape of contact lenses.
Tensile test (physical characteristics and mechanical testing) on soft contact lenses
A tensile test is one of the items required for approvals of soft contact lenses. (Fig.1)
We can test the tensile strength of curve-shaped products without producing flat plates made of lens materials. In this test, the tensile of used sample is lower than the new one.
Other tests for soft contact lens required for approval
We provide various tests required for approval related to soft contact lenses and non-corrective contact lenses in short time. We promote the improvement of technologies by introduction of oxygen permeability equipment for soft contact lenses using electrode method.
|demand items||testing items||cited standards|
|physical characteristics||Shape and outward appearance||ISO 18369-3|
|Base curve||ISO 18369-3|
|Vertex diopter||ISO 18369-3|
|JIS B 7183|
|Luminous transmittance||ISO 18369-3|
|JIS Z 8722|
|Oxygen permeability coefficient||ISO 18369-4|
|Strength||JIS K 7127|
|(JIS K 7113)|
|Refractive index||ISO 18369-4|
|(JIS K 7105)|
|Water content||JIS K 7209|
|Cylindrical refractivity and cylindrical axes||JIS B 7183|
|Prism error||JIS B 7183|
|chemical characteristics||Extractables||ISO 18369-4|
|Monomer residue, additives, colorants|
|disinfectant compatibility||Test for leaching of monomer components, colorants and UV absorbents, Residual property, accumulation, leachability of chemical disinfectant to lens,||PAB Notification No.645 dated March 31, 2011|
|biological characteristics||Cytotoxicity||JIS T 0993-1|
|Sensitization||JIS T 0993-1|
|Irritation/intracutaneous reactivity||JIS T 0993-1|
|Ocular study using rabbit eyes||ISO 9394|
|Genotoxicity||JIS T 0993-1|
|demand for stability||Product stability test||ISO 11987|