I have never heard of or seen this being a problem. My female closes and opens her eyes at intervels to suit herself. Sometimes she closes one eye and looks at me, sometimes both eyes with her head back. As long as they are eating, basking (in temps between 95-110degrees) and moving normally and the eye doesnt appear to be discolored, discharging, or swollen i wouldnt worry about it.
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1.0 green iguana-Deitrich
1.1 Common Boa-Un-Named, Ursula
1.0 Ball Python-Anabell (go figure!)
1.0 Red Tegu-Uteg
1.0 Albino Cal King-Pig
0.1 Mexican Black King-Morticia
1.1 Bearded Dragons-Unnamed, Hanabil
1.0 Albino San Diego Gopher-Unnamed
0.1 Hermans tort-Esio
1.1 JCP-Milton, Medusa
1.1 Reverse Okeetee Corn-Unnamed
0.1 Snow Corn-Unnamed
1.0 Hypo Okeetee Corn-Unnamed
0.1 Motley Okeetee-Unnamed
1.0 Western Hoggie-Wyrm
0.0.1 Rose Hair Taruntla-Unnamed
2.0 Leopard Geckos-Reptar, Pogo
4.1 cats-Tucker,Poe,Abhib,Emerald, Felicity
0.1 Bullmastiff-Asha