1
|
Wang KJ, Wang WW, Tsai CL, Wang IJ. Intraocular pressure changes in eyes with small incision lenticules and laser in situ keratomileusis. Clin Exp Optom 2018; 102:399-405. [PMID: 30556213 DOI: 10.1111/cxo.12861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 10/11/2018] [Accepted: 10/29/2018] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Measuring intraocular pressure after refractive surgery is a challenge in the diagnosis, evaluation, and treatment of glaucoma. Intraocular pressure characteristics after laser in situ keratomileusis (LASIK) are well known. However, intraocular pressure measurement and characteristics after small incision lenticule extraction (SMILE) are still unknown, providing an interesting point of comparison in terms of biomechanical differences from LASIK. METHODS An intraocular pressure analytical model utilising fluid dynamics (simulating air puff) was developed using OpenFoam and Scilab. In addition, solid mechanics (simulating the deformation of the corneal structure) and a ray-tracing technique (simulating applanation detection) simulated by a previously established air-puff Tonovue tonometer were used to simulate post-SMILE and post-LASIK intraocular pressure. RESULTS Based on the proposed model, while at a myopic correction of zero dioptres the difference in intraocular pressure before and after SMILE was 0 mmHg, whereas the difference before and after LASIK was -2.2 mmHg. This trend was observed with a myopic correction up to 12 dioptres. CONCLUSION In a numerical simulation, differences in intraocular pressure in LASIK and SMILE largely resulted from the completeness of the Bowman's membrane resulting from cap or flap creation.
Collapse
Affiliation(s)
| | - Wai W Wang
- Crystalvue Medical Corporation, Taoyuan, Taiwan
| | | | - I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan
| |
Collapse
|
2
|
Comparison of the effect of LASIK parameters on the percent tissue altered (1-dimensional metric) versus percent volume altered (3-dimensional metric). J Cataract Refract Surg 2018; 44:897-904. [DOI: 10.1016/j.jcrs.2018.04.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 01/18/2018] [Accepted: 04/13/2018] [Indexed: 11/18/2022]
|
3
|
Evaluation of corneal biomechanics in patients with keratectasia following LASIK using dynamic Scheimpflug analyzer. Jpn J Ophthalmol 2018; 62:443-450. [PMID: 29700642 DOI: 10.1007/s10384-018-0594-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 03/02/2018] [Indexed: 10/17/2022]
Abstract
PURPOSE To investigate the corneal biomechanics in eyes with keratectasia following LASIK using a dynamic Scheimpflug analyzer. DESIGN Case-Control study. METHOD The subjects in the study included 12 eyes with keratectasia after LASIK (KE), 24 eyes with keratoconus (KC), 17 eyes without keratectasia after LASIK (LASIK), and 34 eyes with normal corneas (Normal). Corneal biomechanics of the four groups were evaluated using a dynamic Scheimpflug analyzer. RESULTS Compared with Normal (7.06 ± 0.54), the radius at the highest concavity (radius, mm) of LASIK (5.96 ± 0.76), KE (4.93 ± 0.61) and KC (5.39 ± 1.02) were significantly small. The Deflection Amplitude (HCDLA, mm) of Normal (0.94 ± 0.07) was significantly lower than those of KE (1.11 ± 0.10) and KC (1.06 ± 0.16), and was not significantly different from that of LASIK (0.98 ± 0.07). There were significant differences between LASIK and KE in radius and HCDLA (P < 0.05), whereas KE and KC had no differences in these parameters. CONCLUSIONS Corneal biomechanical features evaluated using the dynamic Scheimpflug analyzer suggest that biomechanical properties in eyes with keratectasia, keratoconus, and LASIK are different from those of normal eyes. Although the biomechanics in eyes with keratectasia differs from that in eyes with LASIK, it is similar to that in eyes with keratoconus.
Collapse
|
4
|
Fernández J, Rodríguez-Vallejo M, Martínez J, Tauste A, Piñero DP. Corneal biomechanics after laser refractive surgery: Unmasking differences between techniques. J Cataract Refract Surg 2018; 44:390-398. [PMID: 29615281 DOI: 10.1016/j.jcrs.2017.10.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 10/17/2022]
Abstract
The hypothesis that small-incision lenticule extraction provides better preservation of corneal biomechanics than previous laser refractive techniques has led to a growth in the interest in clinical and experimental research in this field. This hypothesis is based on the fact that corneal layers with greater stiffness are preserved with this new technique. However, this hypothesis is controversial because clinical research has shown a great disparity in the outcomes. In this review, we performed an in-depth analysis of the factors that might affect corneal biomechanics in laser refractive surgery procedures from a macrostructural to a microstructural viewpoint. New advances in algorithms with current devices or the introduction of new devices might help unmask the possible advantages of small-incision lenticule extraction in corneal biomechanics.
Collapse
Affiliation(s)
- Joaquín Fernández
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| | - Manuel Rodríguez-Vallejo
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain.
| | - Javier Martínez
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| | - Ana Tauste
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| | - David P Piñero
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| |
Collapse
|
5
|
Kato Y, Nakakura S, Asaoka R, Matsuya K, Fujio Y, Kiuchi Y. Cataract surgery causes biomechanical alterations to the eye detectable by Corvis ST tonometry. PLoS One 2017; 12:e0171941. [PMID: 28222145 PMCID: PMC5319737 DOI: 10.1371/journal.pone.0171941] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 01/27/2017] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Modern cataract surgery is generally considered to bring about modest and sustained intraocular pressure (IOP) reduction. However, the pathophysiological mechanism for this remains unclear. Moreover, a change in ocular biomechanical properties after surgery can affect the measurement of IOP. The aim of the study is to investigate ocular biomechanics, before and following cataract surgery, using Corvis ST tonometry (CST). PATIENTS AND METHODS Fifty-nine eyes of 59 patients with cataract were analyzed. IOP with Goldmann applanation tonometry (IOP-G), axial length, corneal curvature and CST parameters were measured before cataract surgery and, up to 3 months, following surgery. Since CST parameters are closely related to IOP-G, linear modeling was carried out to investigate whether there was a change in CST measurements following cataract surgery, adjusted for a change in IOP-G. RESULTS IOP-G significantly decreased after surgery (mean±standard deviation: 11.8±3.1 mmHg) compared to pre-surgery (15.2±4.3 mmHg, P<0.001). Peak distance (the distance between the two surrounding peaks of the cornea at the highest concavity), maximum deformation amplitude (the movement of the corneal apex from the start of deformation to the highest concavity) and A1/A2 velocity (the corneal velocity during inward or outward movement) significantly increased after cataract surgery (P<0.05) while radius (the central curvature radius at the highest concavity) was significantly smaller following cataract surgery (P<0.05). Linear modeling supported many of these findings, suggesting that peak distance, maximum deformation amplitude and A2 velocity were increased, whereas A2 deformation amplitude and highest concavity time were decreased (after adjustment for IOP change), following cataract surgery. CONCLUSION Corneal biomechanical properties, as measured with CST, were observed to change significantly following cataract surgery. TRIAL REGISTRATION Japan Clinical Trials Registry UMIN000014370.
Collapse
Affiliation(s)
- Yoshitake Kato
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Shunsuke Nakakura
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Ryo Asaoka
- Department of Ophthalmology, The University of Tokyo, Tokyo, Japan
| | - Kanae Matsuya
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Yuki Fujio
- Department of Ophthalmology, Saneikai Tsukazaki Hospital, Himeji, Japan
| | - Yoshiaki Kiuchi
- Department of Ophthalmology and Visual Science, Hiroshima University, Hiroshima, Japan
| | | |
Collapse
|