if i run into retained eye caps, i usually let it wait out til the next shed. in my opinion (and this is what i tell clients, as im in veterinary medicine), the stress (especially to a bigger snake) of holding them down, behind the head, trying to get them off with mineral oil, or whatever seems to cause way more stress for the snake and the keeper, than just keeping the snake well hydrated and moist and wait til they shed again.
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retic is king of kings

1.0 Tiger Retic
1.0 Albino Tiger Retic
0.1 Striped Tiger Retic (het albino)
0.1 Salmon Boa
1.0 Albino Boa
0.1 False Water Cobra