Correlation of ocular aberrations with PTA in myopic femtosecond flap LASIK

Session Details

Session Title: Advanced Tools for Outcome Assessment

Session Date/Time: Tuesday 17/09/2019 | 08:30-10:30

Paper Time: 09:38

Venue: Free Paper Forum: Podium 4

First Author: : V.Murugesan INDIA

Co Author(s): :    S. Azimeera   T. Makhwana   R. Tandon                       

Abstract Details

Purpose:

To evaluate the correlation of ocular aberrations with safe percentage of tissue ablation (PTA) in myopic femtosecond (FS) flap LASIK.

Setting:

Cornea & Refractive Services, Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India

Methods:

In a prospective longitudinal observational study, ocular aberrations were measured using the iTrace system (Tracey Technologies, Houston, Texas) preoperatively and postoperatively at month 1, 3 & 6 in 80 myopic eyes of 40 patients undergoing FS-flap LASIK. Evaluation of the postoperative change in ocular aberrations and correlation analysis of PTA to the changes in ocular aberrations was done by appropriate statistical tests. Data was also analysed in 3 subgroups according to percentage tissue altered (PTA) range – group I: 23.7–26.9; group II: 27.0-32.9; group III:33.0-39.8%.

Results:

Myopic FS-flap LASIK for MRSE -3.50D ± 1.59 (mean PTA 31.59 ± 4.4%) showed a significant change in total corneal aberrations (p <0.001), total LOA (p<0.003) & defocus (p<0.007) at postoperative 6 months. Correlation analysis noted negative correlation of total corneal aberrations (r = -0.44, p = <0.0001), total LOA (r = -0.42, p = <0.0001), defocus (r = -0.34, p = 0.01) & secondary astigmatism (r = - 0.22, p = 0.04) with PTA at postoperative 6months. Data analysis of subgroups observed the postoperative change in total corneal aberrations, LOA & defocus to be significantly different between the subgroups.

Conclusions:

Total corneal aberrations, total LOA and defocus change significantly following myopic FS-flap LASIK in safe range PTA and show significant weak negative correlation to PTA. The postoperative change in total corneal aberrations, total LOA and defocus shows significant difference between the subgroups indicating a greater change with a higher PTA. Postoperative change in higher order aberrations, spherical aberration, secondary astigmatism, coma and trefoil were not statistically significant with not correlation with PTA.

Financial Disclosure:

None