Refinement of Intraocular Pressure Measurements made by Ocular Response Analyzer following Laser in Situ Keratomileusis using M2 90 Moria Microkeratome for Egyptian Myopic and Astigmatic Patients
Introduction: The Goldmann applanation tonometer readings were noted to be markedly reduced after Lasik surgery using a thin flap technique which is widely used nowadays, to correct a wide range of myopia and astigmatism. The Ocular Response Analyzer (ORA) is considered one of the important tools...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Electronic Physician
2016-12-01
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| Series: | Electronic Physician |
| Subjects: | |
| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5279978/ |
| Summary: | Introduction: The Goldmann applanation tonometer readings were noted to be markedly reduced after Lasik
surgery using a thin flap technique which is widely used nowadays, to correct a wide range of myopia and
astigmatism. The Ocular Response Analyzer (ORA) is considered one of the important tools for refinement of
Intraocular Pressure (IOP) measurements. The aim of this study is to evaluate and refine ORA measurements for
IOP changes post- M2 90 Moria microkeratome Lasik procedure for Egyptian myopic and astigmatic patients
trying to aid in glaucoma diagnosis and management.
Methods: Thirty-five eyes of nineteen Egyptian patients with myopia or myopic astigmatism who had undergone
Lasik procedure using M2 90 Moria microkeratome were included in this consecutive case series study. All cases
were subjected to full ophthalmological examination including uncorrected and best corrected visual acuity,
refraction, slit lamp examination, Scheimpflug imaging and ORA (Reichert Ophthalmic Instruments, Inc.,
Buffalo, NY, USA). The refractive errors were measured using an auto refractometer and were confirmed by trial.
For the ocular response analyzer, the Goldmann-correlated IOP measurement (IOPg) which simulates IOP
measured by Goldmann tonometer and the Corneal-Compensated Intraocular Pressure (IOPcc) that takes corneal
biomechanical properties into consideration were reported as well as the Corneal Hysteresis (CH) and the Corneal
Resistance Factor (CRF). Cases were examined preoperatively and again about one month after Lasik, after
stabilization of eye condition. The collected data were tabulated and analysed with the suitable statistical
methods. The mean values and standard deviation were calculated for quantitative data. Comparison tests (t-test)
and correlation tests (Pearson) were also performed.
Results: In our study, involving M2 90 Moria microkeratome Lasik procedure, a highly significant post-Lasik
reduction in IOPg (t-test = 8.62 (p<0.01), and a statistically significant reduction in IOPcc (t-test = 3.37 (p<0.05)
by ocular response analyzer. The average post-Lasik reduction in IOP in mmHg was 4.84±2.82 for IOPg and
2.23±3.51for IOPcc. A statistically significant correlation (p<0.05) existed between post-Lasik reduction of IOPg
and ablation depth as well as preoperative spherical equivalent. A non-significant correlation existed between
post-Lasik reduction of IOPcc and both of ablation depth and preoperative spherical equivalent.
Conclusions: Following Lasik procedure using M2 90 Moria microkeratome, the IOPcc values by ORA were
closer to the preoperative values than the IOPg values and the reduction of IOPcc values was not affected by
ablation depth (i.e. preoperative spherical equivalent). Therefore, it is advisable to use the IOPcc values by ORA
when evaluating post-Lasik patients for glaucoma diagnosis and management, but with the addition of the
average value for post-Lasik reduction which in the study was 2.23±3.51mmHg. |
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| ISSN: | 2008-5842 2008-5842 |