Personalised eye modelling for customised intraocular lens designs Matthew Sheehan, Eamonn...

Personalised eye modelling for customised intraocular lens designs

Matthew Sheehan, Eamonn O’Donoghue, Conor Sheil and Alexander Goncharov

Photonics Ireland, Dublin, Ireland, September 7th- 9th 2011

History• Ridley’s first intraocular lens – 1949

• Kelman’s first phacoemulsification procedure - 1967

• First FDA approval for an intraocular lens - 1981

• Refractive surgery increases in popularity – 1990s

• Geometrical optics equations - 1973

• Linear regression equations - 1980

• Modern formula - 1980s to 1990s

Intraocular lens power calculations

What lens power should we use ?

€

P =nvitl − c

−naq

(naq /K) − c

€

P = A − 2.5l − 0.9K

Refractive surgery popularity increases

Experiment

Protocol – measurements performed pre and post cataract surgery

• Wavefront aberration of the eye (ZyWave)

• Refractive error and corneal curvature (Nidek ARK)

• Segmented axial length (Lenstar)

• Corneal topography (Atlas)

• Interferometry on the specific intraocular lenses (FISBA)

Aims

• Investigate corneal shape changes due to the surgical incision

• Find parameters for predicting the implant resting position/depth

• Perform surface metrology for a specific implant design

Final Goal

• Aquire knowledge to perform personalised eye modelling for customised intraocular lens designs

Biometry data summary

• 165 patients enrolled (64 males, 101 females)

• 33 excluded eyes

• 303 included suitable eyes (pre-surgery)

• age range: 32 to 98 years (mean 74 years)

• 88 eyes with usable post-surgery review data

• 74 eyes with usable single-echo implant data

• 14 eyes with usable double-echo implant data

• review period: 10 to 122 days (mean 31 days)

Lens implantation depth

Cornea ~ 500 microns

Cataractous Lens ~ 4 mm

Retina ~ 200 microns

Intraocular lens ~ 900 microns

Vitreous ~ 16 mm

Predicting lens implantation depth

Surgery-induced corneal topography changes

Personalised eye modeling

Conclusions• Early days for personalised eye modelling and

customised intraocular lens designs

• Modern biometry instruments allow accurate measurement of two key parameters

- optical segmented axial length - posterior corneal topography

• This methodology may be beneficial for typical cataract surgery patients as well as those with extreme ocular parameters (previous refractive surgery patients, high hyperopia)