Posters

A new post-myopic refractive surgery formula based on swept-source optical coherence tomography

Poster Details

First Author: T.Yeo SINGAPORE

Co Author(s):                        

Abstract Details

Purpose:

To determine the accuracy of a new post refractive surgery formula based on swept source optical coherence tomography (OCT) data.

Setting:

Department of Ophthalmology, Tan Tock Seng Hospital, Singapore

Methods:

Total keratometry measurements from 51 eyes with previous myopic laser refractive surgery were obtained using IOLMaster 700 (Zeiss, Jena, Germany). A regression formula to obtain a predicted posterior radius was developed based on the correlation between the measured anterior and posterior radii. The total corneal power obtained is then applied to the Haigis formula. A comparative study of a separate 28 eyes was then performed using the new modified Haigis formula and compared to existing no history methods of Barrett True-K without history, Haigis-L and Shammas PL, and history methods of Barrett True-K with history, Masket and modified Masket.

Results:

Average laser refractive correction was -6.75D (range -0.75 to -10.5D). The modified Haigis formula had the lowest mean absolute error (0.399), median absolute error (0.393), standard deviation (0.476) and highest percentages of eyes within 0.5D (75.0%) and 1.0D (92.86%). For no history methods, the mean absolute error, median absolute error and percentages within 0.5D and 1D were: Barrett True-K (0.470, 0.460, 57.1%, 89.3%), Haigis-L (0.615, 0.598, 46.4%, 75.0%), Shammas PL (0.485, 0.396, 57.1%, 89.3%). For history methods, they were: Barrett True-K (0.581, 0.553, 46.4%, 85.7%), Masket (0.528, 0.434, 57.1%, 85.7%), modified Masket (0.655, 0.570, 42.9%, 75.0%)

Conclusions:

The new modified Haigis formula is able to accurately predict for post myopic refractive surgery cases.

Financial Disclosure:

None