Online eyewear firm Lenskart today said it has earmarked about USD 2-3 million to invest in companies that are working on either products or technologies that can help provide affordable eyecare solutions. As part of this strategy, the Ratan Tata-backed firm has invested USD 500,000 (about Rs 3.3 crore) in US-based ThinOptics. "We will invest about USD 2-3 million... These…