Allvar Gullstrand

Allvar Gullstrand was a Swedish doctor who invented  Slit lamp for illuminating and examining eye. It is still used by ophthalmologists. He obtained his PhD in ophthalmology from the university of Uppsala and became a professor there. 

Gullstrand did intensive research on the structure of eye and function of the eye, especially into how it refracts light. He studied the lens extensively and to find out how it adjusts itself to focus on both near and distant objects -- called accommodation. He was able to show with experiments that the refractive power of the lens increased during accommodation and was 50 % greater than had been previously calculated. 

He described the structure and function of cornea in detail. He also devised improved corrective lenses for use after cataract surgery. Gullstrand was also interested in corneal astigmatism in which light is refracted unevenly due to the irregular shape of the eye ball. He was the first to use precise mathematical calculations to determine the power of the lenses used to correct refractive errors. 

Allvar Gullstrand received Nobel Prize for his work on Dioptrics in 1911. 

	Nobel Prize for Medicine ' 99
	List of Nobel Prize winners for Medicine