CataractCoach™ 2004: understanding aspheric IOLs

Today almost all of the IOLs that we use have an aspheric design with either negative spherical aberration or zero spherical aberration. This video was made from a powerpoint presentation that I created in 2006! And it will give you a concise summary to understand aspheric IOLs.
Spherical lenses have a constant curvature on their surface, much in the same way that a sphere has a constant curvature. However, the power of the lens at different points is variable, resulting in relative defocus of more peripheral light rays. Due to this constant curvature, these lenses are easier to make; however, their optics are worse. A perfectly aspheric lens has a variable curvature but a constant power even at the periphery of the lens. This results in the same focus of all light rays, both central and peripheral. These lenses are more challenging to make, but their optics are better.
Peripheral light rays are relatively defocused in spherical lenses, resulting in a degradation of image quality. In an aspheric lens, the peripheral light rays are focused at the same point as the central rays, resulting in a sharper, higher-quality image.
Because of their superior optics, aspheric lenses have become the standard for high-end cameras, surgical microscopes, slit lamps and even high-quality glasses and contact lenses. In fact, for nearly 50 years ophthalmologists have been using aspheric 20 D lenses to examine retinas via the binocular indirect ophthalmoscope. The benefits of the aspheric 20 D lens are many: the image quality is good, there is no distortion of the image at the periphery of the lens and the lens is relatively immune to decentration or tilt. For comparison, try examining the retina with the 20 D from your spectacle trial lens set!

[@dr.alan.niemies]

Fantastic! I finished ophthalmology residency last year and this is the first time I really understood the topic so easily. Thanks a lot for your invaluable teaching! Your videos will help generations to come. :)

[@dronasinha6610]

Wow ,I have read many books some journals some lectures ,but this lecture is the best ,very easy simple understanding .co relating Images graphs are superb for better understanding .
We know about abberations and using in cataract and refractive surgeries ,but this lecture is refreshing .
One new point I learned, depth is better with zero spherical abbr .never considered depth in Rxing abbr

[@_Hannuy_Choi_]

I wish I could hit LIKE button 100 times. Thank you so much for this excellent lecture !!

[@ruhelchacko2359]

An absolute masterclass. Brilliant.

[@MrFMANT]

Thanks for this great presentation.

[@eye.yashas]

Excellent lecture. Thank you!

[@bills6825]

Dr Devan, having been diagnosed with cataracts, is among looking for information and found your channel the content is fantastic, thank you very much. I have met with several surgeons and would like to ask you a question. One of the surgeons strongly recommended has recommended having a Lipiflow procedure done before the cataract surgery (a better surgical outcome). I have searched and have not been able to find anything that relates cataract surgery outcome to the Lipiflow procedure. What are your thoughts on the need or benefits of doing this before cataract surgery? Thank you the excellent videos

[@Dr.AdnanAlHassani]

Up to the point!
Breef and precize

[@pankajmangulkar2100]

Very nice sir thank you very much💐💐

[@PiyushGupta-qv3ki]

Sir please make such videos also highlighting pathophysiology

[@shreesai_906]

Please make video on achieving myopic against the rule astigmatism after phaco surgery to achieve near vision with monofocal IOLS

[@PiyushGupta-qv3ki]

Amazing

[@khadijabenmoussa8816]

Super 👍

[@aavvaallooss2]

Is the Tecnis Eyhance a good choice in a post myopic LASIK patient? Eyhance has -SA but plays with spherical aberration to enhanced depth of focus

[@sajaljain5684]

With all due respect doctor , a spherical surface will focus on a single point , and vice versa with the aspherical surface