Relationship between minimum corneal thickness and refractive state, keratometry, age, sex, and left or right eye in refractive surgery candidates

Purpose: To analyze the correlation between age, gender, refractive error, keratometry, and corneal thickness in a large group of subjects. Methods: This study is a retrospective analysis of patients who underwent refractive surgery between January 2000 and February 2015 at Care Vision Refractive Clinic, Tel Aviv, Israel. Patient demographics, subjective refraction, pachymetry, and average keratometry were collected. Results: Overall, 51,113 eyes of patients averaging 28.8 ± 9.3 years of which 53.9% were males were included. Average keratometry, spherical equivalent and cylindrical error differed significantly between male and female subjects (p < 0.001), while pachymetry did not (p = 0.332). In myopic eyes, correlations between age, pachymetry, average keratometry, spherical equivalent, and cylindrical error were all statistically significant except for the correlation between age and either pachymetry (p = 0.462) or spherical equivalent (p = 0.016). All correlations found were negligible or small (|r|= 0.003 to 0.141). In hyperopic eyes, correlations between age, pachymetry, average keratometry, spherical equivalent, and cylindrical error were all statistically significant except for the correlation between average keratometry and either pachymetry or cylindrical error (p = 0.344 or p = 0.274, respectively). All correlations found were negligible or small, except for a moderate correlation found between age and cylindrical error (r = 0.365). Conclusion: Refractive state, pachymetry, and keratometry of refractive surgery candidates are mostly weakly correlated.

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Correlation between Central Corneal Thickness and Degree of Myopia among Malaysian Patients Undergoing Laser Keratorefractive Surgery

Journal of Advances in Medicine and Medical Research ◽

10.9734/jammr/2020/v32i2230705 ◽

2020 ◽

pp. 52-58

Author(s):

Sagili Chandrasekhara Reddy ◽

Mohd Mansor Shariff ◽

Aina Malindri Dasrilsyah

Keyword(s):

Optical Coherence Tomography ◽

Refractive Surgery ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

Anterior Segment ◽

Military Hospital ◽

Moderate Degree ◽

Optical Coherence ◽

Corneal Refractive Surgery ◽

The Mean

Purpose: To determine the central corneal thickness in myopic adult patients scheduled for laser corneal refractive surgery and to explore its correlation with degree of refractive error. Materials and Methods: The case records of 130 myopic patients who underwent laser corneal refractive surgery in a military hospital over a period of two years were reviewed to determine the central corneal thickness. All patients had 6/6 vision with best correction, and did not have any other anterior segment or fundus diseases in both eyes. The central corneal thickness was measured with Visante Carl Zeiss anterior segment optical coherence tomography instrument. Results: Out of 130 patients, males were more (73, 56.2%); mean age of patients was 33.8 years (range 18-60 years) and majority were Malays (110, 84.6%). The spherical power of myopia ranged from – 0.5 to – 10.00 D, and the cylindrical power ranged from – 0.25 to – 3.25 D. The mean central corneal thickness of both eyes was 528.2 µm (range 331- 615 µm); in the mild degree of myopia (- 0.50 to - 2.00 D) 527.9 µm, moderate degree (- 2.25 to -5.00 D) 529.4 µm, and high degree (-5.25 to -11.00 D) 523.9 µm. Conclusion: The anterior segment optical coherence tomography provides noncontact, rapid, pachymetry mapping of the corneal thickness. In Malaysian patients, the mean central corneal thickness of both eyes in myopia was 528.1 µm (range 331- 615 µm). There was no correlation between the mean central corneal thickness and degree of myopia, different genders, age groups, ethnic groups and two eyes.

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Management of Glaucoma Following Intraocular Procedures

Glaucoma ◽

10.1093/oso/9780199757084.003.0013 ◽

2012 ◽

Author(s):

Raghu C. Mudumbai

Keyword(s):

Refractive Surgery ◽

Structural Integrity ◽

Corneal Thickness ◽

Topical Steroid ◽

Applanation Tonometry ◽

Dynamic Contour Tonometry ◽

Glaucomatous Optic Neuropathy ◽

Clinical Appearance ◽

Clinical Procedures ◽

Pressure Spike

The development of glaucoma can occur postoperatively from corneal/refractive, cataract, and vitreoretinal surgery. Additionally, glaucoma may be noted after clinical procedures have been performed, including injections and laser procedures. This chapter is organized into two basic sections: postoperative and post-procedure glaucoma. Background: Currently little is known about the effect of refractive surgery in glaucoma patients or about patients who undergo refractive procedures and may go on to develop glaucoma. •IOP measurement •Measurement of IOP after refractive surgery can be challenging. Corneal properties that are altered after refractive surgery include corneal thickness, corneal curvature, the structural integrity (stiffness or hysteresis), as well as the overlying tear film that interacts with instruments that measure IOP. Photorefractive keratectomy (PRK) additionally ablates portions of Bowman’s layer, which may change corneal resistance. Nomograms have been developed to adjust for IOP change after corneal alteration but usually take only corneak thickness into account, which has led to little success in their use. •Goldmann applanation tonometry (GAT) assumes corneal thickness = 520 microns. Thicker corneas will overestimate IOP and thinner corneas, which result from refractive procedures such as PRK and LASIK, will underestimate IOP. Therefore, GAT may have limited value in measuring true IOP following refractive surgery. Other tonometric devices, like Pascal dynamic contour tonometry, pneumatonometry, and the Reichert ocular response analyzer, may be more accurate. There does not appear to be any simple conversion table that can be referenced in correcting measured IOP after the cornea is altered surgically. Preoperative IOP is probably the most important variable that should be recorded. •The intraoperative pressure spike associated with LASIK may occur in select patients, leading to the development of glaucomatous optic neuropathy. • Pressure-induced stromal keratitis (PISK) is a condition related to steroid-induced elevated IOP that may occur after LASIK. The clinical appearance is similar to diffuse lamellar keratitis (DLK), where there is a diffuse interlamellar haze covering the flap. DLK is an inflamatory response where IOP is not elevated and requires topical steroid treatment for resolution.

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Significance of dynamic contour tonometry in evaluation of progression of glaucoma in patients with a history of laser refractive surgery

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2018-313771 ◽

2019 ◽

Vol 104 (2) ◽

pp. 276-281 ◽

Cited By ~ 1

Author(s):

Sang Yeop Lee ◽

Eun Woo Kim ◽

Wungrak Choi ◽

Chan Keum Park ◽

Sangah Kim ◽

...

Keyword(s):

Refractive Surgery ◽

Open Angle Glaucoma ◽

Corneal Thickness ◽

Significant Risk ◽

Applanation Tonometry ◽

Dynamic Contour Tonometry ◽

Significant Difference ◽

History Of ◽

The Mean ◽

Laser Refractive Surgery

AimsIn this study, we tested the hypothesis that intraocular pressure (IOP) parameters measured by dynamic contour tonometry (DCT) would be more relevant in progression of glaucoma when there is a history of laser refractive surgery (LRS) than the IOP parameters measured by Goldmann applanation tonometry (GAT) or calculated by correction formulae.MethodsNinety-eight eyes in 54 patients with open-angle glaucoma and a history of LRS were included in this retrospective study. IOP was measured by both GAT and DCT during follow-up. Baseline, mean, and peak IOP, IOP fluctuation, and IOP reduction were measured by each tonometry method. Corrected IOP parameters using central corneal thickness and mean keratometry values were also analysed. Clustered logistic regression was used to identify variables correlated with progression of glaucoma. Areas under the curve (AUCs) for correlated variables were also compared.ResultsThe mean DCT value (OR 1.36, p=0.024), peak DCT value (OR 1.19, p=0.02) and pattern SD (OR 1.10, p=0.016) were significant risk factors for progression. There was a significant difference in the predictive ability of the mean DCT and GAT values (AUC 0.63 and 0.514, respectively; p=0.01) and of the peak DCT and GAT values (0.646 and 0.503, respectively, p=0.009). The AUCs for corrected IOP did not exceed those of DCT.ConclusionsIOP measurements were more associated with progression of glaucoma when measurements were obtained by DCT than by GAT or correction formulae in eyes with a history of LRS.

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Comparison of Intraocular Pressure before and after Laser In Situ Keratomileusis Refractive Surgery Measured with Perkins Tonometry, Noncontact Tonometry, and Transpalpebral Tonometry

Journal of Ophthalmology ◽

10.1155/2015/683895 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Isabel Cacho ◽

Juan Sanchez-Naves ◽

Laura Batres ◽

Jesús Pintor ◽

Gonzalo Carracedo

Keyword(s):

Intraocular Pressure ◽

Refractive Surgery ◽

Corneal Thickness ◽

Laser In Situ Keratomileusis ◽

Spherical Equivalent ◽

Transpalpebral Tonometry ◽

Spherical Equivalent Refraction ◽

Before And After ◽

Noncontact Tonometry

Purpose. To compare the intraocular pressure (IOP) before and after Laser In Situ Keratomileusis (LASIK), measured by Diaton, Perkins, and noncontact air pulse tonometers.Methods. Fifty-seven patients with a mean age of 34.88 were scheduled for myopia LASIK treatment. Spherical equivalent refraction (SER), corneal curvature (K), and central corneal thickness (CCT) and superior corneal thickness (SCT) were obtained before and after LASIK surgery. IOP values before and after surgery were measured using Diaton, Perkins, and noncontact air pulse tonometers.Results. The IOP values before and after LASIK surgery using Perkins tonometer and air tonometers were statistically significant (p<0.05). However, no significant differences were found (p>0.05) for IOP values measured with Diaton tonometer. CCT decreases significantly after surgery (p<0.05) but no statistical differences were found in SCT (p=0.08). Correlations between pre- and postsurgery were found for all tonometers used, withp=0.001andr=0.434for the air pulse tonometer,p=0.008andr=0.355for Perkins, andp<0.001andr=0.637for Diaton.Conclusion. Transpalpebral tonometry may be useful for measuring postsurgery IOP after myopic LASIK ablation because this technique is not influenced by the treatment.

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Comparison between OrbscanIIz, Pentacam, Ultrasound Pachymetry (Tomey SP-100) at Different Stages of Keratoconus

Ophthalmology Research An International Journal ◽

10.9734/or/2020/v13i230163 ◽

2020 ◽

pp. 7-33

Author(s):

E. Pateras ◽

Ch. Koufala

Keyword(s):

Correlation Coefficient ◽

Study Design ◽

Refractive Surgery ◽

Corneal Thickness ◽

Cross Linking ◽

Moderate Correlation ◽

Measurement Systems ◽

Ultrasound Pachymetry ◽

Collagen Cross Linking ◽

Corneal Collagen

Aims: To compare results of OrbscanIIz and Pentacam and Ultrasound pachymetry at different stages of keratoconus on corneal thickness. Sample and Study Design: 94 keratoconic patients participated in the study, of which 52 were men and 42 women. Keratoconus patients were measured with OrbscanIIz, Pentacam and Ultrasound pachymetry in pre-operation examinations for corneal collagen cross-linking. The patients belong to different keratoconus stages. Place and Duration of Study: University of West Attica Dept Biomedical Sciensce Course Optics & Optometry in collaboration with Athens “Ophthalmologico” Clinic during the period between October 2017 to January 2019. Methodology: Corneal Pachymetry maps correlation of three types of corneal pachymeters OrbscanIIz, Pentacam and Ultrasound pachymetry (Tomey SP-100 Pachymeter). The measurements of the thinnest point of the cornea from each patient were collected at different stages of keratoconus and compared. Results: A sample of 188 eyes were measured at different stages of keratoconus and compared for the thinnest corneal thickness with three different measurement systems, OrbscanIIz ,Pentacam and Ultrasound pachymetry. At sublinical stage Orbscan-Pentacam had Correlation coefficient r=0,7971, Orbscan-Ultrasound r=0,7483 and Pentacam-Ultrasound r=0,9442. At 1st stage Orbscan-Pentacam had Correlation coefficient r=0,8913, Orbscan-Ultrasound r=0,8151 and Pentacam-Ultrasound r=0,8151. At 2nd stage Orbscan-Pentacam had Correlation coefficient r=0,9339, Orbscan-Ultrasound r=0,8819 and Pentacam-Ultrasound r=0,9633. For 3rd stage Orbscan-Pentacam had Correlation coefficient r=0,8317, Orbscan-Ultrasound r=0,8457 and Pentacam-Ultrasound r=0,9633. For 4th stage Orbscan-Pentacam had Correlation coefficient r=-0,4655, Orbscan-Ultrasound r=0,3089 and Pentacam-Ultrasound r=0,9633. In Iatrogenic keratoectasiaafter refractive surgery Orbscan-Pentacam had Correlation coefficient r=0,9327, Orbscan-Ultrasound r=0,3089 and Pentacam-Ultrasound r=0,9859. Conclusion: Statistical differences between OrbscanIIz, Pentacam and Ultrasound pachymetry were found for corneal thickness in all stages of keratoconus for the thinnest point measured. Orbscan-Pentacam have statistical significant differences but weak to moderate correlation. Orbscan-Ultasound have also statistical significant differences their correlation is very weak, while Pentacam-Ultrasound have statistical significant differences smaller as the previous but their correlation is very strong at all stages of keratoconus.

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Reversal of Myopic Correction for Patients Intolerant to LASIK

Journal of Ophthalmology ◽

10.1155/2021/7113676 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Amr A. Gab-Alla

Keyword(s):

Refractive Surgery ◽

Average Duration ◽

Corneal Thickness ◽

Case Series ◽

Spherical Equivalent ◽

Efficacy And Safety ◽

Effective Option ◽

Optical Zone ◽

The Mean ◽

One Year

Purpose. To evaluate the outcome of the reversal of myopia correction in patients intolerant to LASIK. Methods. This study is a retrospective and case series of patients who decided to reverse their previous myopic LASIK correction between July 2012 and July 2020. It was conducted at a private refractive surgery centre, Ismailia, Egypt. The patients were followed up after reversal treatment for one year. Primary LASIK and reversal treatment were performed by a 500 kHz Amaris excimer laser platform. The main outcomes included refractive predictability, stability, efficacy, and safety and any reported complications. Results. This study included 48 eyes of 24 patients (6 male and 18 female patients). The average duration between the primary LASIK surgery and reversal treatment was 3.20 ± 0.30 months (range 3 to 4 months). Reversal treatment was bilateral in all patients. The mean age of the patients was 38 ± 1.9 years (range 37 to 45 yrs). After reversal, the mean postreversal cycloplegic refraction spherical equivalent was −1.82 ± 0.34 D (range −1.50 to −3.00 D). The mean ablation depth was 34.10 ± 7.36 μm (range 20 to 46 μm), and the mean of the central corneal thickness 12 months after reversal treatment was 510.2 ± 14.4 μm (range 515 to 487 μm). The mean keratometric reading was 42.6 ± 1.6 (range 42.5 to 44.8). The mean of CDVA was 0.2 ± 0.03 log MAR (range −0.10 to 0.4 log MAR). The mean optical zone of reversal treatment was 6.1 ± 0.3 mm (range 5.9 to 6.2 mm). UDVA was 0.4 log MAR in 87.5% of the patients, 0.5 log MAR in 8.3% of the patients, and 0.6 log MAR in 4.2% of the patients. CDVA remained unchanged in 83.3% of patients; 2.1% of the patients gained one line of CDVA (Snellen); 8.3% of the patients lost one line of CDVA; 6.3% of the patients lost two lines of CDVA. No cases of corneal ectasia were recorded. The only postoperative complications were flap microfolds in 3 eyes (6.25%). Conclusion. In conclusion, this study demonstrates that reversal of myopic LASIK treatment is a safe, stable, and effective option for intolerant patients.

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Corneal Thickness after Refractive Surgery

Ophthalmology ◽

10.1016/j.ophtha.2005.03.007 ◽

2005 ◽

Vol 112 (9) ◽

pp. 1637.e1 ◽

Cited By ~ 6

Author(s):

William C. Stewart ◽

Jessica N. Jenkins ◽

Jeanette A. Stewart

Keyword(s):

Refractive Surgery ◽

Corneal Thickness

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Human eye ocular component analysis for refractive state and refractive surgery

International Journal of Ophthalmology ◽

10.18240/ijo.2017.07.09 ◽

2017 ◽

Keyword(s):

Refractive Surgery ◽

Component Analysis ◽

Human Eye ◽

Refractive State

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Evaluation of preoperative dry eye in people undergoing corneal refractive surgery to correct myopia

International Journal of Ophthalmology ◽

10.18240/ijo.2021.07.13 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1047-1051

Author(s):

Peng-Fei Zhao ◽

◽

Ya-Bin Hu ◽

Kai Cao ◽

Ying Qi ◽

...

Keyword(s):

Influencing Factors ◽

Dry Eye ◽

Refractive Surgery ◽

Corneal Thickness ◽

Tear Film ◽

Corneal Curvature ◽

Related Factors ◽

History Of ◽

Corneal Refractive Surgery ◽

Male Patients

AIM: To investigate the incidence of preoperative dry eye and related factors in patients undergoing corneal refractive surgery to correct myopia. METHODS: A total of 141 patients with myopia who underwent corneal refractive surgery were surveyed by questionnaires, tear film break-up time (BUT) test, Schimer I test (SIt), corneal fluorescein staining (FL) test and diagnosed according to the currently recognized domestic diagnostic criteria for dry eye. Correlation analysis of factors such as age, gender, regular wearing of contact lens (CL), diopter (spherical equivalent), corneal thickness, and corneal curvature that may affect the onset of dry eye was carried out to clarify the main influencing factors. RESULTS: There were 64 patients (45.39%) diagnosed with dry eye. The male patients (20.31%) was significantly less than that of non-dry eye subjects (41.56%; χ2=7.260, P=0.007); the proportion of patients with dry eye wearing CL (81.25%) was significantly higher than that of non-dry eye subjects (51.95%; χ2=13.234, P<0.001); the median diopter level of dry eye patients was -6.59 (IQR: -8.87, -4.58) D, and the median diopter level of non-dry eye subjects was -5.69 (IQR: -7.15, -4.03) D. The diopter level of dry eye patients was significantly higher (Z=-2.086, P=0.019). However, the age, best corrected visual acuity, and intraocular pressure of dry eye patients were not statistically different from those of non-dry eye subjects (t=-0.257, -0.383 and 0.778, P=0.798, 0.702, and 0.438); the corneal thickness and corneal curvature (K1 and K2) were also not statistically different either (Z=-1.487, -1.036 and -1.707, P=0.137, 0.300, and 0.088). The research further analyzes the three significant factors in the single factor analysis (gender, CL wear, and diopter) in a multi-factor way: CL wear and diopter were the influencing factors of dry eye disease. Among them, CL wear increased the risk of dry eye by 2.934 times compared with no CL wear; for every 1 D increase in diopter, the risk of dry eye increased by 0.761 times. CONCLUSION: Preoperative dry eye is relatively common in patients who undergo corneal refractive surgery to correct myopia, especially in patients who have a history of CL wear and a high diopter level before surgery. Therefore, it is necessary to carry out preoperative screening and timely treatment of dry eye to obtain the best treatment outcome and postoperative satisfaction.

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