Manual Visual Inspection is an important step in pharmaceutical manufacturing which aids in the detection of various formulation defects. The defects are observed in the all types of formulations viz. tablets, capsules, injectables etc. To effectively observe the defects there are many requirements w.r.t. trained and qualified operators, Inspection belt, lighting, background etc.

In this series on pharmaceutical product inspection, we shall be discussing various aspects of manual visual inspection serially.

Accordingly, this article shall provide information on Lighting requirement of Manual Visual Inspection.

Lighting: Proper lighting is the most important requirement of the inspection process as it may influence the efficacy of inspection adversely. As a general rule, higher the illumination, higher will be the inspection efficacy. Lighting with an illumination intensity between 2000 and 3750 lux are normally considered acceptable at the inspection table especially for clear glass vials in parenteral preparation. However, it may be noted that for tablet, capsules and other dosage forms illumination requirements may be well established and validated, and should be designed to facilitate defect detection. For injectables in clear glass vial, the inspection shall never be carried out on an illumination level below 2000 lux.

Lighting may be fluorescent, incandescent, spot, and/or polarized, and must be non-glaring. It should be evenly spread across the inspection zone. Higher intensity lights can be used for colored glass containers and plastic containers. For such containers light intensity of 10000 Lux may be required.

Light-emitting diodes (LED) offer an energy efficient, stable source of light without the added heat of incandescent lamps.

There should be a periodic check of the light intensity using lux meter on the inspection belt and area to verify if the lux level meets the required limits. Frequency of verification should be well established. Any failure in meeting the requisite acceptance criteria shall trigger the corrective action. Any replacement of lights due to failure shall be qualified for illumination level before the area is released for normal operation. Surrounding area shall also be well lit.