In Vivo Real-Time Intraocular Pressure Variations during LASIK Flap Creation

Chaurasia, Shyam S.; Gimeno, Federico; Tan, K.; Yu, Shang Juan; Tan, Donald; Beuerman, Roger W.; Mehta, Jodhbir S.

doi:10.1167/iovs.10-5228

Cited by 60 publications

(41 citation statements)

References 29 publications

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“…Docking of the eye into the LASIK interface is known to cause a significant rise in intraocular pressure, in the order of Z80 mm Hg. 17,18 Although this has been linked to complications such as LASIK-induced optic neuropathy, 19 it is generally well tolerated by the younger refractive surgery population. 10 However, this rise in intraocular pressure is likely to be more problematic in elderly cataract patients, with the risk of ischaemic retinal and optic nerve injury.…”

Section: Docking the Eyementioning

confidence: 99%

The journey to femtosecond laser-assisted cataract surgery: new beginnings or a false dawn?

Trikha

Turnbull

Morris

et al. 2013

Eye

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Femtosecond laser-assisted cataract surgery (FLACS) represents a potential paradigm shift in cataract surgery, but it is not without controversy. Advocates of the technology herald FLACS as a revolution that promises superior outcomes and an improved safety profile for patients. Conversely, detractors point to the large financial costs involved and claim that similar results are achievable with conventional small-incision phacoemulsification. This review provides a balanced and comprehensive account of the development of FLACS since its inception. It explains the physiology and mechanics underlying the technology, and critically reviews the outcomes and implications of initial studies. The benefits and limitations of using femtosecond laser accuracy to create corneal incisions, anterior capsulotomy, and lens fragmentation are explored, with reference to the main platforms, which currently offer FLACS. Economic considerations are discussed, in addition to the practicalities associated with the implementation of FLACS in a healthcare setting. The influence on surgical training and skills is considered and possible future applications of the technology introduced. While in its infancy, FLACS sets out the exciting possibility of a new level of precision in cataract surgery. However, further work in the form of large scale, phase 3 randomised controlled trials are required to demonstrate whether its theoretical benefits are significant in practice and worthy of the necessary huge financial investment and system overhaul. Whether it gains widespread acceptance is likely to be influenced by a complex interplay of scientific and socio-economic factors in years to come.

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Section: Docking the Eyementioning

confidence: 99%

The journey to femtosecond laser-assisted cataract surgery: new beginnings or a false dawn?

Trikha

Turnbull

Morris

et al. 2013

Eye

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“…The mean difference was calculated by subtracting the baseline IOP from the highest IOP in each phase and deriving the mean value. 13 All procedures were performed by J.S.M. and R.I.A.…”

Section: In Vivo Real-time Iop Studymentioning

confidence: 99%

“…FS-LASIK was performed according to a previously described protocol. 13 The laser parameters for the FS-LASIK flaps were 110 m flap thickness; 7.9 mm flap diameter, 170 nJ power, spot distance and tracking spacing of 4.8 m/4.8 m for the flap, and 2 m/2 m for side cuts, respectively.…”

Section: In Vivo Real-time Iop Studymentioning

confidence: 99%

“…13,15 Eyes undergoing FLEx had almost twice the duration of exposure to suction and increased IOP compared with the eyes that underwent FS-LASIK, but given the relatively low pressures, this is unlikely to have clinical consequences. Finally, an objective grading system of flap and bed surfaces imaged with SEM for both FLEx and FS-LASIK revealed comparably smooth surfaces with both procedures.…”

Section: 10mentioning

confidence: 99%

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Femtosecond Lenticule Extraction (FLEx): Clinical Results, Interface Evaluation, and Intraocular Pressure Variation

Ang

Chaurasia

Angunawela

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To characterize the clinical profile of femtosecond lenticule extraction (FLEx) correlated with ultrastructural analysis of the corneal interface and in vivo real-time intraocular pressure (IOP). METHODS. Prospective clinical case series with experimental studies; consecutive patients underwent FLEx at a single tertiary center over 10 months with postsurgical follow-up of 3 months. The patients were divided into three groups according to spherical equivalence (SE) (A, Ͻ Ϫ5.0 diopters [D]; B, Ն Ϫ5.00 D and Ͻ Ϫ9.00 D; and C, Ն Ϫ9.0 D). Twelve human cadaveric eyes analyzed using scanning electron microscopy after receiving FLEx; 40 rabbit eyes received FLEx with in vivo IOP measurements. The main outcome measures were refractive outcomes from study subjects; with corneal interface and IOP in experimental studies. RESULTS. Thirty-three subjects (22 females, 66.7%) underwent FLEx in both eyes (66 eyes). Mean age was 32 years (range, 21 to 46 years). Preoperative mean SE was Ϫ5.77 Ϯ 2.04 D with astigmatism of Ϫ1.03 Ϯ 0.72 D. There was a slight hyperopic shift (mean SE 0.14 Ϯ 0.53 D); 94% achieved uncorrected visual acuity Ն20/25 3 months postoperatively. Refractive stability was achieved within 1 month (P Ͻ 0.001). Ultrastructurally, the smoothness of the corneal interface was independent of ablation depth (mean irregularity scores A, B, C: 8.8 Ϯ 0.6, 10.3 Ϯ 0.4, 8.7 Ϯ 0.6, respectively; P ϭ 0.88). The increase in IOP during FLEx was similar to that in femtosecond (FS)-LASIK, albeit a twofold duration of raised IOP in FLEx (P Ͻ 0.001). CONCLUSIONS. These results suggest that FLEx is predictable and effective in treating myopia and myopic astigmatism. Experimental studies support the early clinical results and safety of this procedure. (Invest Ophthalmol Vis Sci. 2012;53: 1414 -1421) DOI:10.1167/iovs.11-8808 T he femtosecond (FS) laser is a near-infrared neodymiumdoped yttrium aluminum garnet (ND:YAG) laser that photodisrupts the cornea with surgical precision through plasma cleavage of stromal lamellae.1 The first commercial ophthalmic FS laser was introduced into the market in 2001 for laser in situ keratomileusis (LASIK) flaps. Since then, significant improvements in laser energy profiles, spatial resolution, and faster laser speeds have occurred.2 FS lasers have thus made a significant impact on refractive surgery by enabling nonmechanical creation of a corneal flap during LASIK. The FS laser offers several advantages over manual microkeratomes including increased precision, reduced incidence of flap complications, and the ability to cut thinner flaps without the risk of buttonhole formation.3,4 Moreover, newer generation FS lasers have reduced problems such as transient lightsensitivity syndrome and interference by cavitation bubbles. 5,6

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“…The short-term IOP increase may damage the papilla in nonglaucomatous eyes as well as eyes with preexisting glaucoma [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

et al. 2018

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Purpose: Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. Methods: The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). Results: A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). Conclusion: The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma.

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In Vivo Real-Time Intraocular Pressure Variations during LASIK Flap Creation

Cited by 60 publications

References 29 publications

The journey to femtosecond laser-assisted cataract surgery: new beginnings or a false dawn?

The journey to femtosecond laser-assisted cataract surgery: new beginnings or a false dawn?

Femtosecond Lenticule Extraction (FLEx): Clinical Results, Interface Evaluation, and Intraocular Pressure Variation

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

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