This study is researching 2 experimental drugs, REGN5713 and REGN5715. The study drugs will be either of these drugs given alone (either REGN5713 or REGN5715) or given together (REGN5713 and REGN5715) to reduce eye allergy signs and symptoms due to birch tree pollen allergy. The aim of the study is to see how safe and effective the study drugs are at lowering eye allergy signs and symptoms compared with placebo. The study will also evaluate whether the combination (REGN5713-5715) has different effectiveness than REGN5713 or REGN5715 alone. The study is looking at several other research questions, including: * What side effects may happen from taking the study drugs * How much of the study drugs is in the blood at different times * Whether the body makes antibodies against the study drugs (which could make the drug less effective or could lead to side effects)