When to choose a high index lens?

Each index has an optimal prescription range. The best person to choose the right index for you is a dispenser or optician. Some benefits include flatter base curves that help shed some of the lens thickness and weight when prescribed correctly. 

1.50: 1.32g specific gravity with Abbe Value 58. Developed as a replacement for glass lenses during World War 2. This material tints well and is lightweight. Optimal range: +2.00 to -3.00

1.53: Impact resistant, high optical clarity, and in lens UV protection. Specific gravity is 1.11g, Abbe Value is 43-45. Designed as a material to offer combinations of excellent optics, strength characteristics, and ultra lightweight qualities in a single lens material. Optimal range: +3.00 to -3.00

1.58 (Quatrex): Impact resistant, high optical clarity, chemical and heat resistant, easy to edge, easy drilling, and lightweight. 1.25g specific gravity, 48 Abbe Value. Optimal range: +4.00 to -6.00

1.60: Thinner lenses, UV protection, specific gravity 1.22g, Abbe Value 41. Optimal range: +4.00 to -6.00

1.67: Thinner lenses, UV protection, specific gravity 1.36g, Abbe Value 31. Optimal range: +3.00 to +6.00 and -6.00 to -10.00.

1.74: Thinnest lenses, UV protection, specific gravity 1.46g, Abbe Value 32. Optimal range: +6.00/-9.00 and above.

Going into high index lenses when it is not necessary can in fact inhibit vision. Higher index lenses can be heavier when not required, have a higher reflectance, and can sometimes have a lesser abbe value creating more chromatic aberration when not required. Because higher index materials have greater surface reflectance and therefore at increased risk of troublesome reflections it is generally accepted that mid, high and very high index materials should always have anti reflection added to them.