Modifiers E1, E2, E3 and E4 are used when the code is specific for an eyelid. While the eyes are bilateral (we have 2 in mirror image), we have 4 eyelids, so they are not considered bilateral. In the case of procedures such as 67800-67808 - Excision of chalazion or 67810 Inscisional biopsy of eyelid skin, the use of -LT, -RT or -50 would be inappropriate as you don't have a right or left eyelid, but you have a left upper eyelid and a left lower eyelid, so the E1-E4 modifiers would be appropriate to describe which eyelid(s) was treated. If 67810 is performed on more than one lid, the second and subsequent lids would be subject to a multiple procedure reduction.
Hope that helps,
Karen Hill, CPC, CPB, CPMA
AHIMA Approved ICD-10-CM Trainer