Changes in corneal biomechanics and intraocular pressure following Femto-LASIK using Goldman applanation tonometry and ocular response analyzer

Ahmed Yassin Hemida; Omar M Said; Asser A E Abdel-Meguid; Mohammed Iqbal; Amani E Badawi

doi:10.18240/ijo.2020.05.13

Changes in corneal biomechanics and intraocular pressure following Femto-LASIK using Goldman applanation tonometry and ocular response analyzer

Int J Ophthalmol. 2020 May 18;13(5):782-787. doi: 10.18240/ijo.2020.05.13. eCollection 2020.

Authors

Ahmed Yassin Hemida¹, Omar M Said², Asser A E Abdel-Meguid³, Mohammed Iqbal⁴, Amani E Badawi⁵

Affiliations

¹ Department of Ophthalmology, Fayoum Ophthalmic Hospital, Fayoum 63514, Egypt.
² Department of Ophthalmology, Faculty of Medicine, Fayoum University, Fayoum 63514, Egypt.
³ Department of Ophthalmology, Faculty of Medicine, Cairo University, Cairo 11562, Egypt.
⁴ Department of Ophthalmology, Faculty of Medicine, Sohag University, Sohag 8242, Egypt.
⁵ Department of Ophthalmology, Faculty of Medicine, Mansoura University, Mansoura 35516, Egypt.

Abstract

Aim: To compare intraocular pressure (IOP) measurements before and after laser in situ keratomileusis (LASIK) with a femtosecond laser for flap creation using ocular response analyzer (ORA) and Goldmann applanation tonometry, and to identify factors that may influence the preoperative and postoperative IOP.

Methods: A prospective study conducted on myopic patients who underwent LASIK using a femtosecond laser for flap fashioning. Enrolled patients were evaluated preoperatively, 6wk and 3mo postoperatively for manifest refraction (MR), keratometric (K) readings and central corneal thickness (CCT) using a scheimpflug-based topography. Corneal resistance factor (CRF), corneal hysteresis (CH), Goldmann correlated IOP (IOPg) and corneal compensated IOP (IOPcc) were measured using ORA besides IOP assessment by Goldman applanation tonometry (GAT).

Results: There was a statistically significant decrease in measures of IOPg by 3.35±0.83 mm Hg, followed by GAT which decreased by 2.2±0.44 mm Hg, and the least affected by operation was IOPcc which decreased only by 0.87±0.1 mm Hg after 6wk. After 3mo follow up there was a statistically significant decrease in IOPcc which decreased only by 0.76±0.4 mm Hg, followed by IOP GAT by 1.6±0.5 mm Hg, and the most affected by operation was IOPg which decreased by 2.3±0.3 mm Hg. Correspondingly, there was a statistically significant decrease in CH and CRF after 6wk and 3mo. At 3mo, the preoperative MR and preoperative GAT were prominent significant predictors of the postoperative GAT changes. The prediction equation was subsumed.

Conclusion: IOP measurements and corneal biomechanical factors reduce significantly after LASIK with a femtosecond laser for flap creation. The IOPcc values are less influenced by changes in corneal properties than IOPg and GAT, indicating that IOPcc may provide the most reliable measurement of IOP after this procedure.

Keywords: corneal biomechanics; femtosecond laser; intraocular pressure; laser in situ keratomileusis; myopia; ocular response analyzer.

International Journal of Ophthalmology Press.