Abstract
Purpose:
Lipid layer is part of the tear film responsible for ocular surface lubrication and prevention of aqueous layer evaporation. Nowadays, dysfunction of this tear film layer is recognized as responsible for the majority of tear film dysfunction cases. In the same time, there is no method of tear film lipid layer visualization that became a part of routine clinical practice. Tearscope and Tearscope plus instruments, designed for lipid layer examination, were not widely accepted by general ophthalmologists or optometrists primarily because of their price, and furthermore are not being manufactured anymore. Currently, several sophisticated lipid layer assessent instruments are being developed, but despite their precision, their complexity and price will most likely limit their use to research and specialized dry eye clinics. The author thus tried to design simple, cheap and practical instrument for tear film lipid layer assessment using widely available parts.
Methods:
By using interferometry method, wide and bright white light reflection from the tear film lipid layer visualized on the slit lamp is created by modified standard handheld LED torch. Being handheld, it is possible to use it in assessing LLT on different parts of the ocular surface and on different slit lamps.
Results:
The handheld tear film LLT assessment tool, despite its simplicity, showed clinically acceptable characteristics, making it possible to include LLT measurement in everyday ophthalmology and optometry practice. Furthermore, by shining the light very obliquely, it s possible to observe tear film breaks which essentialy represent visualization of non-invasive tear film break-up.
Conclusions:
Handheld LLT assessment tool has proven in practice to be equally dependable as Tearscope, while in the same time being much more practical due to its small size and only slightly more expensive than ordinary handheld torch. It is already being used in several Croatian ophthalmology clinics as well as in some Hungarian. Also, it is undergoing clinical evaluation in Germany and Israel. The author of this instrument hopes that it will help ophthalmologists and optometrists to make tear film lipid layer examination a part of their routine clinical practice, as well as observing tear film stability non-invasively.
Keywords: 486 cornea: tears/tear film/dry eye