Abstract: An electronic device may have optical components that each have first and second transparent layers such as first and second glass layers. The glass layers may have outer surfaces that face away from each other and inner surfaces that face towards each other. A polymer layer is formed between the inner surfaces of the glass layers. Along the periphery of each optical component, a hermetic seal is formed to protect the polymer material of the polymer layer. The seal may have a moisture barrier layer that is attached to the first and second glass layers. The moisture barrier layer may be supported by an elastomeric buffer member. The moisture barrier layer may be formed from metal film or a polymer layer or other substrate that is coated with a moisture-impermeable coating. The moisture-impermeable coating may be formed from one or more thin-film metal layers and/or one more thin-film dielectric layers.