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)