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

Authors

  • Tamer Adel Refai Refractive Unit, Ophthalmology Department, Research Institute of Ophthalmology, Giza, Egypt

Keywords:

Thin flap Lasik, the Goldmann-correlated IOP, Corneal-Compensated Intraocular Pressure, ablation depth, Egypt

Abstract

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±3.51 for 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±3.51 mmHg.

 

References

Grødum K, Heijl A, Bengtsson B. A comparison of glaucoma patients identified through mass screening

and in routine clinical practice. Acta Ophthalmol Scand. 2002; 80(6): 627-31. doi: 10.1034/j.1600- 0420.2002.800613.x. PMID: 12485284.

Kniestedt C, Punjabi O, Lin S, Stamper RL. Tonometry through the ages. Surv Ophthalmol. 2008; 53(6):

-91. doi: 10.1016/j.survophthal.2008.08.024. PMID: 19026320.

Doughty MJ, Zaman ML. Human corneal thickness and its impact on intraocular pressure measures: a

review and meta-analysis approach. Surv Ophthalmol. 2000; 44(5): 367-408. doi: 10.1016/S0039- 6257(00)00110-7. PMID: 10734239.

Harada Y, Hirose N, Kubota T, Tawara A. The Influence of Central Corneal Thickness and Corneal

Curvature Radius on The Intraocular Pressure as Measured By Different Tonometers: Noncontact and

Goldmann Applanation Tonometers. J Glaucoma. 2008; 17(8): 619-25. doi:

1097/IJG.0b013e3181634f0f. PMID: 19092456.

Medeiros FA, Weinreb RN. Evaluation of the influence of corneal biomechanical properties on intraocular

pressure measurements using the ocular response analyzer. J Glaucoma. 2006; 15(5): 364-70. doi:

1097/01.ijg.0000212268.42606.97. PMID: 16988597.

Wong TT, Wong TY, Foster PJ, Crowston JG, Fong CW, Aung T. The relationship of intraocular pressure

with age, systolic blood pressure, and central corneal thickness in an asian population. Invest Ophthalmol

Vis Sci. 2009; 50(9): 4097-102. doi: 10.1167/iovs.08-2822. PMID: 19458324.

Liu J, Roberts CJ. Influence of corneal biomechanical properties on intraocular pressure measurement:

quantitative analysis. J Cataract Refract Surg. 2005; 31(1): 146-55. doi: 10.1016/j.jcrs.2004.09.031. PMID:

Schmack I, Auffarth GU, Epstein D, Holzer MP. Refractive surgery trends and practice style changes in

Germany over a 3-year period. J Refract Surg. 2010; 26(3): 202-8. doi: 10.3928/1081597X-20090515-05.

PMID: 20229953.

Chang DH, Stulting RD. Change in intraocular pressure measurements after LASIK the effect of the

refractive correction and the lamellar flap. Ophthalmology. 2005; 112(6): 1009-16. doi:

1016/j.ophtha.2004.12.033. PMID: 15882906.

Pepose JS, Feigenbaum SK, Qazi MA, Sanderson JP, Roberts CJ. Changes in corneal biome¬chanics and

intraocular pressure following LASIK using static, dynamic, and noncontact tonometry. Am J Ophthalmol.

; 143(1): 39-47. doi: 10.1016/j.ajo.2006.09.036. PMID: 17188041.

Sullivan-Mee M, Billingsley SC, Patel AD, Halverson KD, Alldredge BR, Qualls C. Ocular Response

Analyzer in subjects with and without glaucoma. Optom Vis Sci. 2008; 85(6): 463-70. doi:

1097/OPX.0b013e3181784673. PMID: 18521025.

Shousha SM, Abo Steit MA, Hosny MH, Ewais WA, Shalaby AM. Comparison of different intraocular

pressure measurement techniques in normal eyes, post surface and post lamellar refractive surgery. Clin

Ophthalmol. 2013; 7: 71-9. doi: 10.2147/OPTH.S37978. PMID: 23326186, PMCID: PMC3544333.

Luce D. Methodology for Corneal Compensated IOP and Corneal Resistance Factor for An Ocular

Response Analyzer. Invest Ophthalmol Vis Sci. 2006; 47(13): 2266.

Shin J, Kim TW, Park SJ, Yoon M, Lee JW. Changes in biomechanical properties of the cornea and

intraocular pressure after myopic laser in situ keratomileusis using a femtosecond laser for flap creation

determined using ocular response analyzer and Goldmann applanation tonometry. J Glaucoma. 2015;

(3): 195-201. doi: 10.1097/IJG.0b013e31829da1ec. PMID: 23807345.

Published

2022-03-07