A series of papers by Jay M. Enoch of the School of Optometry at the University of California at Berkeley and various collaborators published in peer-reviewed journals have quite remarkable findings. I have referenced two papers here & but there are many more published. The papers investigate the eye structures in statues dated to the IVth and Vth dynasty and show that the ancient Egyptians were grinding and polishing quartz crystal into optical quality lenses circa 4,600 years ago.
The statues, including Le Scribe Accroupi / the seated scribe exhibit an optical effect that as an observer walks around the statue, the eyes appear to follow the observer. The eyes that produce this effect are polished crystal quartz set into a structure that mimics various aspects of the human eye (refer to  for a complete description).
A common theme to the papers is the quality of the manufacture indicates that these lenses were not the first lenses created:
“Because of both quality of performance (and, hence, quality of fabrication), and complexity in design, we regard it highly doubtful that the lenses coupled to eye structures in antique Egyptian statues were the first lenses created”
“Because of their complexity, unique applications and quality, it seems doubtful that these were the first lenses” 
In attempting to re-create the optical effect in , the authors note that their experimental setup did not re-create the effect in entirety due to distortions in their lens, remarking “the ancient Egyptian lenses were of better quality”
The reserve lens studied in  contains both a convex front face and concave rear face which is assumed to be a similar construct to the seated scribe’s lens. Other lenses studied by the authors have convex/straight edge and biconvex designs. These extraordinary lenses and Enoch and collaborators work to analyse them provide evidence the ancient Egyptians (if somewhat limited geographically, limited in time scale and almost certainly specialised) studied and understood optics to construct a multi-element structure. The science to create optical quality lenses appears, in an advanced state, during the same era as the ancient Egyptians advanced the art of True Pyramid construction. In a curious parallel, the optical lens capability seemingly degrades in quality and disappears from the record. This leads naturally to the question of the source of this skill. The authors suggest the capability may have been imported to Egypt via trade or war, likely from Mesopotamia . This suggestion is also supported by Thanos5150 in this forum .
 The Nimrud Lens / The Layard Lens, accessed 28 May 2019 from [www.britishmuseum.org]
 Jay M. Enoch and Vasudevan Lakshminarayanan, Ophthal. Physiol. Opt. Vol. 20, No. 2, pp. 126-130, 2000 “Duplication of unique optical effects of ancient Egyptian lenses from the IV/V Dynasties: lenses fabricated 2620-2400 BC or roughly 4600 years ago”
 Jay M Enoch et al, 2018, unpublished paper “Lenses and Visual illusion Measured at the Louvre Paris: The Eyes of the Statue "Le Scribe Accroupi" (E-3023, ca. 2475 BCE, Egyptian, Old Kingdom) and a Unique Reserve Eye (E-3009), accessed from Researchgate.net in May 2019;
 Lee Anderson (Thanos5150) provides a brief write-up of the statues and images in the thread and suggests a possible Mesopotamia link in the thread here [grahamhancock.com]