Theoretical model and design of a device to reduce the influence of environmental factors on refractive surgery outcomes

Schena, Emiliano; Silvestri, Sergio; Franzesi, Giovanni Talei; Cupo, Gaetano; Carito, Pino; Ghinelli, Emiliano

doi:10.1109/iembs.2006.4397405

Cited by 5 publications

(5 citation statements)

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“…In this way, SMILE surgery avoids or minimizes errors associated with excimer laser ablation, such as stromal hydration, [3] laser fluence, [4][5][6] environmental temperature, and relative humidity. [7] Therefore, the thickness of the intrastromal lenticule created at the beginning of the surgery determines the safety and accuracy of SMILE surgery. A close consistency would be expected between the predicted and achieved lenticule thickness.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Predictability and Influence factors of the Achieved Lenticule Thickness in Small Incision Lenticule Extraction

Yin

Chen

et al. 2019

Preprint

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Background To evaluate the differences between the predicted and achieved lenticule thickness (ΔLT) after small incision lenticule extraction (SMILE) surgery and investigate relationships between ΔLT and refractive errors or lenticule depth in SMILE. Methods A total of 184 eyes from 184 consecutive patients who underwent SMILE were included in this prospective study. One eye for each patient was randomly selected and included for statistical analysis. An ultrasound pachymetry measurement and Scheimpflug camera corneal topography were obtained before and at 3 months after SMILE. The achieved lenticule thickness was calculated by comparing the preoperative examinations with postoperative examinations using ultrasound pachymetry and Pentacam software measurements. The pupil center and corneal vertex were selected as the 2 locations for measurement calculation on Pentacam. Analysis of variance (ANOVA) was performed to compare mean pachymetry values using different instruments. An independent t test was performed to evaluate the difference in ΔLT between different cap thicknesses. Linear regression analyses were performed between the VisuMax readout lenticule thicknesses and the measured maximum corneal change, the preoperative spherical equivalent (SE) and each ΔLT. Results On average, the achieved lenticule thickness measured with ultrasound pachymetry was 13.02 ± 8.87 μm thinner than the VisuMax readout lenticule thickness. Linear regression analysis showed significant relationships between the predicted and each achieved lenticule thickness. The preoperative SE was significantly related to each ΔLT (ultrasound: R2 =0.279; at corneal vertex: R2 =0.252; at pupil center R2 =0.246). The ΔLT measured by ultrasound pachymetry was significantly smaller in the thick cap group (cap thickness above 120 μm) than in the thin cap group (P < 0.01). Conclusions An overestimation of achieved lenticule thickness was found in this study. The ΔLT was related to the preoperative SE correction. Furthermore a lager ΔLT was found under a thin cap.

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Section: Introductionmentioning

confidence: 99%

Investigation of Predictability and Influence factors of the Achieved Lenticule Thickness in Small Incision Lenticule Extraction

Yin

Chen

et al. 2019

Preprint

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“…Environmental thermo hygrometric (temperature and humidity) factors were previously studied, presumably creating an under correction during refractive surgery by absorbing laser fluence. 13,14 De Souza et al 15 and Walter and Stevenson 16 reported that elevated room temperature and humidity results in worse visual outcomes. However, Randleman et al 17 did not find that room temperature and humidity have any effect on surgical results.…”

Section: Discussionmentioning

confidence: 99%

Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis

Friehmann

Assad

Rabina

et al. 2019

European Journal of Ophthalmology

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Purpose: To determine factors associated with early flap misalignment following microkeratome-assisted laser in situ keratomileusis. Materials and Methods: This retrospective study included the right eyes of consecutive patients who underwent laser in situ keratomileusis procedure between 2005 and 2016 at Care-Vision Laser Centers, Tel-Aviv, Israel. Patients were divided into two groups according to whether or not they subsequently developed early flap misalignment. Results: A total of 14,582 eyes (mean age of patients: 32.4 ± 10.3 years) were included. Post-laser in situ keratomileusis early flap misalignment developed in 158 eyes (1.1%). Misalignment was more frequent during the spring (32.3% vs 22.8%, p = 0.003) and in a higher operating room temperature (23.34 ± 1.06 vs 22.98 ± 1.26, p < 0.001). In addition, in the misalignment group, there was a higher rate with the of use of the a Moria M2 microkeratome (rather than sub-Bowman’s keratomileusis microkeratome) head (55.2% vs 40.5%, respectively, p < 0.001). In a multivariable analysis adjusted for surgeon and year of surgery, high operating room temperature (odds ratio = 1.22, p = 0.006), treatment zone of 9.0 mm (as opposed to smaller treatment zones, odds ratio = 1.54, p = 0.04), and springtime (odds ratio = 1.58, p = 0.02) were associated with flap misalignment. There was a significant difference in misalignment rates between surgeons (p = 0.02). Conclusion: This study found that larger treatment zones, higher operating room temperature, operating during the spring, and the use of Moria M2 microkeratome were associated with increased flap misalignment rates. The association with operating room temperature and seasonal variation is of interest and merits further research.

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“…As a consequence, several environmental factors (e.g., the use of anesthetics and topical mydriatic agents, long surgery, high temperature and/or low humidity in the operating room, and the intensity of the microscope illumination) may compromise lubrication of the ocular surface and leave the cornea hazy. 6 , 13 Therefore, agents that maintain optimal hydration and corneal transparency must be applied to the ocular surface to ensure a clear view for the surgeon and prevent damage and discomfort to the patient. BSS, which is the most commonly used corneal wetting agent, has the disadvantage of leaving the cornea hazy because it tends to evaporate quickly; therefore, frequent irrigations are required, which may harm the epithelium, stroma, and endothelium.…”

Section: Discussionmentioning

confidence: 99%

Tripolymeric Corneal Coating Gel Versus Balanced Salt Solution Irrigation During Cataract Surgery: A Retrospective Analysis

Giardini¹,

Hauranieh

Gatto³

et al. 2018

Cornea

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Purpose:To compare the protective properties and ease of manipulation during cataract surgery of corneal coating with a gel (eyeDRO; AL.CHI.MI.A. S.R.L, Italy) and corneal irrigation with balanced salt solution (BSS).Methods:We analyzed the data of 51 patients receiving either eyeDRO or BSS during routine cataract surgery performed within a 20-day period in 2016. The selected parameters were intraoperative clarity and ease of manipulation; postoperative epithelial integrity; and patient discomfort.Results:Compared with BSS irrigation, eyeDRO coating significantly increased intraoperative clarity and ease of manipulation (P < 0.01). Single application was required in eyeDRO-treated eyes, whereas BSS was applied 5.3 ± 0.4 times on average (P < 0.01). Two hours postoperatively, a normal epithelium was observed in 90.0% and 60.0% of eyeDRO-coated and BSS-irrigated eyes, respectively; punctate epithelial damage was observed in 9.7% and 40.0% (P < 0.05) of eyeDRO-coated and BSS-irrigated eyes, respectively; eye irritation and foreign body sensation were experienced by 13.0% and 37.0% of eyeDRO-treated patients and by 65.0% and 100% of BSS-treated patients, respectively (P < 0.01). Twenty-four hours postoperatively, 80.0% of BSS-treated patients versus 19.0% of eyeDRO-treated patients still experienced foreign body sensation (P < 0.01).Conclusions:EyeDRO coating was shown to be a safer and more effective option than BSS irrigation in cataract surgery because single application provided optimal hydration and intraoperative clarity during the entire surgery, better preserved the corneal epithelium, and offered postoperative comfort to the patient.

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Theoretical model and design of a device to reduce the influence of environmental factors on refractive surgery outcomes

Cited by 5 publications

References 0 publications

Investigation of Predictability and Influence factors of the Achieved Lenticule Thickness in Small Incision Lenticule Extraction

Investigation of Predictability and Influence factors of the Achieved Lenticule Thickness in Small Incision Lenticule Extraction

Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis

Tripolymeric Corneal Coating Gel Versus Balanced Salt Solution Irrigation During Cataract Surgery: A Retrospective Analysis

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