Original sentence: The writings of Pliny the Elder (23–79) also show that burning-glasses were known to the Roman Empire, and mentions what is possibly the first use of a corrective lens: Nero was said to watch the gladiatorial games using an emerald (presumably concave to correct for myopia, though the reference is vague)
Edited sentence: The writings of Pliny the Elder (23–79) also show that burning-glasses were known to the Roman Empire, and mentions what is possibly the first use of a corrective lens: Nero was known to watch the gladiatorial games using an emerald (presumably concave to correct for myopia, though the reference is vague)