1
|
Guo L, Cheng Z, Kong X, Huang Z, Xu X, Wu J, Lv H. The effect of different angle kappa on higher-order aberrations after small incision lenticule extraction. Lasers Med Sci 2023; 38:277. [PMID: 38012462 PMCID: PMC10682276 DOI: 10.1007/s10103-023-03934-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 11/12/2023] [Indexed: 11/29/2023]
Abstract
This study aimed to compare higher-order aberrations (HOAs) after small incision lenticule extraction (SMILE) in patients with different angle kappa. This is a retrospective report in which 341 right eyes of 341 patients who were subjected to SMILE, which used coaxially sighted corneal light reflex (CSCLR) as the treatment zone centered, treated by the same experienced surgeon (LHB) for correction of myopia and myopic astigmatism, preoperative and postoperative spherical equivalent (SE), angle kappa, total higher-order aberrations (total HOA), spherical aberration (SA), vertical coma (VC), horizontal coma (HC), oblique trefoil (OT), and horizontal trefoil (HT), were compared. SMILE showed outstanding performance in terms of safety, efficacy, and predictability. In addition, a comparison of preoperative and postoperative HOAs exhibited the difference of total HOA (P < 0.01), SA (P < 0.01), VC (P < 0.01), and HC (P < 0.01), which was statistically significant; however, for OT and HT with the longer follow-up time, the statistical difference gradually decreased. For stratification of angle kappa into groups based on decantation, angle kappa was divided into three major groups: r < 0.1 mm, 0.1 ≤ r < 0.2 mm, and r ≥ 0.2 mm; the changes of SA (F = 4.127, P = 0.021) and OT (F = 3.687, P = 0.031) exhibited significant difference after 1 year of SMILE. We performed a correlation analysis of all preoperative and postoperative parameters, and the results indicated that the preoperative total HOA was negatively correlated with preoperative cylindrical diopter (DC), and postoperative total HOA, SA, and coma were affected by spherical diopter (DS) and SE. Moreover, we also found a significant difference of SA and VC in the early postoperative with preoperative. SA was positively correlated with Y values and r of 1 year after SMILE. All of the analyzed parameters in the three groups, except for the trefoil, gradually increased over time; however, the trefoil could gradually stabilize over time. We also divided angle kappa into four groups by quadrants; the result showed that the effects of higher-order aberrations were markedly different from the various quadrants. Patients with large angle kappa were able to increase VC and SA postoperatively, and higher HOAs were more significant in patients with high myopia. The differences in quadrants exhibited a diversity of HOAs; this could be attributed to the corneal surface reestablishment and the alteration of angle kappa, but the trend was not apparent. Although all patients displayed increased HOAs after SMILE, the potential application of CSCLR as the treatment zone centered still showed excellent safety, efficacy, and predictability.
Collapse
Affiliation(s)
- Lu Guo
- The First Affiliated Hospital of Jinan University, Guangzhou, 510000, Guangdong Province, China
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China
| | - Zixuan Cheng
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China
| | - Xiangmei Kong
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China
| | - Zhaoxia Huang
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China
| | - Xue Xu
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China
| | - Jinchuan Wu
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China
| | - Hongbin Lv
- The First Affiliated Hospital of Jinan University, Guangzhou, 510000, Guangdong Province, China.
- The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan Province, China.
| |
Collapse
|
2
|
Sun L, Lin HN, Jhanji V, Ng TK, Ji RF, Zhang R. Changes in effective optical zone after small-incision lenticule extraction in high myopia. Int Ophthalmol 2022; 42:3703-3711. [PMID: 35781597 DOI: 10.1007/s10792-022-02367-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 04/28/2022] [Indexed: 02/05/2023]
Abstract
PURPOSE To evaluate the four measurement approaches on the determination of effective optical zone (EOZ) using Scheimpflug tomography after small-incision lenticule extraction surgery in eyes with high myopia. SETTING Corneal refractive surgery conducted in an eye hospital in southern China. DESIGN This is a retrospective cohort study. METHODS In total, 74 subjects were recruited. EOZ was measured at 3 months postoperatively using vertex-based (EOZV), pupil-based (EOZP), 4 mm-ring-based total corneal refraction method (EOZ4) and tangential curvature difference map method (EOZD), and their consistencies were compared. EOZs and planned optical zone (POZ) were compared and analyzed with eccentricity, ablation degree (AD) and total corneal aberrations. RESULTS At 3 months after surgery, the mean root mean square of ΔHOA, ΔComa, ΔTrefoil and ΔSA were 0.53 ± 0.27 μm, 0.36 ± 0.20 μm, 0.01 ± 0.84 μm and 0.16 ± 0.14 μm, respectively. EOZV, EOZP, EOZ4 and EOZD were 5.87 ± 0.44 mm, 5.85 ± 0.45 mm, 4.78 ± 0.40 mm and 5.29 ± 0.27 mm, respectively, which were significantly smaller than POZ 6.48 ± 0.16 mm. Bland-Altman plots showed a good consistency among the four EOZs. The difference between the EOZV and EOZP was 0.02 mm within the range of clinically acceptable difference. In addition, the eccentricity was positively correlated with ΔHOA, ΔComa and ΔSA. CONCLUSIONS All 4 measurement approaches demonstrated the reduction of EOZs compared to POZ. The EOZV was the closest to POZ, followed by EOZP. The ΔEOZs showed no significant difference with eccentricity, AD and corneal aberrations.
Collapse
Affiliation(s)
- Lixia Sun
- Joint Shantou International Eye Center of Shantou University, The Chinese University of Hong Kong, North Dongxia Road, Shantou, 515041, Guangdong, China
| | - Hui-Ni Lin
- Joint Shantou International Eye Center of Shantou University, The Chinese University of Hong Kong, North Dongxia Road, Shantou, 515041, Guangdong, China
| | - Vishal Jhanji
- Shantou University Medical College, Shantou, Guangdong, China
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong
- Department of Ophthalmology, UPMC Eye Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tsz Kin Ng
- Joint Shantou International Eye Center of Shantou University, The Chinese University of Hong Kong, North Dongxia Road, Shantou, 515041, Guangdong, China
- Shantou University Medical College, Shantou, Guangdong, China
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong
| | - Rui-Feng Ji
- Joint Shantou International Eye Center of Shantou University, The Chinese University of Hong Kong, North Dongxia Road, Shantou, 515041, Guangdong, China
| | - Riping Zhang
- Joint Shantou International Eye Center of Shantou University, The Chinese University of Hong Kong, North Dongxia Road, Shantou, 515041, Guangdong, China
| |
Collapse
|
3
|
Zhao X, Zhang L, Ma J, Li M, Zhang J, Zhao X, Wang Y. Comparison of Wavefront-Guided Femtosecond LASIK and Optimized SMILE for Correction of Moderate-to-High Astigmatism. J Refract Surg 2021; 37:166-173. [PMID: 34038300 DOI: 10.3928/1081597x-20201230-01] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare refractive outcomes, higher order aberrations (HOAs), and the changes in contrast sensitivity after wavefront-guided femtosecond laser-assisted in situ keratomileusis (WFG LASIK) and optimized small incision lenticule extraction (SMILE) for moderate-to-high astigmatism correction. METHODS This prospective, randomized study included 87 eyes: 40 eyes in the WFG LASIK group and 47 eyes in the SMILE group. Manual cyclotorsion compensation by marking the horizontal axis before SMILE surgery was used for optimized SMILE. Refractive diopter, aberrations, and contrast sensitivity were assessed 3 months postoperatively. The Alpins vector analysis method was used to analyze the astigmatic changes after surgery. RESULTS There were no significant differences in the corrected distance visual acuity and refraction between the two groups after surgery. The fitted curve of surgically induced astigmatism versus target induced astigmatism was described as y = 0.9905 x + 0.0009 in the WFG LASIK group and y = 0.9672 x + 0.0026 in the SMILE group. The percentage of corneal astigmatism axis change within 5 degrees was statistically significant (chi-square test: 10.632, P = .001). HOAs increased in both the WFG LASIK and SMILE groups after surgery (t = -3.655, P = .001, t = -3.784, P = .001, respectively). However, comparison of the changes of HOAs between both groups was not significant (t = -0.565, P = .575). The improvement in contrast sensitivity in the WFG LASIK group was significantly higher than that in the SMILE group. CONCLUSIONS WFG LASIK and optimized SMILE can achieve similar outcomes for astigmatism correction. Optimized SMILE with marking could achieve good astigmatism correction, even without an eye tracking system. [J Refract Surg. 2021;37(3):166-173.].
Collapse
|
4
|
External infrared light for excimer laser vision correction. J Cataract Refract Surg 2020; 46:1055. [PMID: 32773550 DOI: 10.1097/j.jcrs.0000000000000168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
5
|
The best optical zone for small-incision lenticule extraction in high myopic patients. J Cataract Refract Surg 2020; 46:1302-1307. [PMID: 32569029 DOI: 10.1097/j.jcrs.0000000000000282] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Small-incision lenticule extraction (SMILE) is an effective and safe procedure for the correction of myopia due to minimally invasive and noncorneal flap surgery. However, the SMILE procedure has certain requirements for corneal cap thickness, attempted refractive correction, residual stromal bed thickness, and optical zone diameter, which sometimes make surgeons hesitant to choose SMILE or other refractive surgeries. The requirements limit its use in patients with high myopia. The purpose of this review was to find the optimal parameters of SMILE through discussing the best optical zone for high myopic patients, the visual quality of different optical zones, the choice of corneal cap thickness, and their effects on corneal biomechanical parameters, so surgeons can provide reference recommendations for patients with high myopia in choosing a reasonable and safe procedure.
Collapse
|
6
|
Damgaard IB, Ang M, Mahmoud AM, Farook M, Roberts CJ, Mehta JS. Functional Optical Zone and Centration Following SMILE and LASIK: A Prospective, Randomized, Contralateral Eye Study. J Refract Surg 2019; 35:230-237. [PMID: 30984980 DOI: 10.3928/1081597x-20190313-01] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/13/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare centration and functional optical zone (FOZ) after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (LASIK). METHODS In this prospective, randomized, single-masked, paired-eyed, clinical trial, 70 patients received SMILE in one eye and LASIK in the other eye for myopia and myopic astigmatism. FOZ was calculated using custom software on 3-month postoperative refractive power maps (Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany). Programmed treatment area was defined as the total area of the programmed OZ plus the transition zone. Centration was evaluated by the linear distance between FOZ centroid and the pupil center and the corneal apex. RESULTS The average preoperative spherical equivalent (-5.38 ± 1.65 vs -5.45 ± 1.61 diopters [D]), postoperative spherical equivalent (0.05 ± 0.39 vs 0.06 ± 0.39 D), uncorrected distance visual acuity (0.01 ± 0.13 vs 0.00 ± 0.08 logMAR), and corrected distance visual acuity (-0.07 ± 0.10 vs -0.07 ± 0.10 logMAR) were comparable in SMILE- and LASIK-treated eyes of the 60 patients with complete datasets (P > .419). Postoperative increase in spherical aberration was lower in SMILE than in LASIK (0.08 ± 0.16 vs 0.17 ± 0.18 µm, P = .002). The FOZ area was significantly larger in SMILE than in LASIK (30.25 ± 3.60 vs 29.21 ± 3.72 mm2), despite the smaller programmed OZ diameter (6.48 ± 0.08 vs 6.52 ± 0.11 mm) and smaller programmed treatment area (33.87 ± 0.81 vs 46.30 ± 2.61 mm2, P < .037). Pupil centration (0.43 ± 0.21 vs 0.41 ± 0.22 mm) and apex centration (0.48 ± 0.24 vs 0.48 ± 0.22 mm) were comparable between SMILE and LASIK (P > .694). CONCLUSIONS SMILE created a larger FOZ than LASIK, despite the smaller programmed OZ. This may be due to a difference in the biomechanical response between the two procedures. Visual outcome and centration were comparable between SMILE and LASIK. [J Refract Surg. 2019;35(4):230-237.].
Collapse
|
7
|
Mohammadi SF, Nabovati P, Mirzajani A, Ashrafi E, Vakilian B. Risk factors of regression and undercorrection in photorefractive keratectomy: a case-control study. Int J Ophthalmol 2015; 8:933-7. [PMID: 26558204 DOI: 10.3980/j.issn.2222-3959.2015.05.14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 01/30/2015] [Indexed: 11/02/2022] Open
Abstract
AIM To determine risk factors of regression and undercorrection following photorefractive keratectomy (PRK) in myopia or myopic astigmatism. METHODS A case-control study was designed in which eyes with an indication for re-treatment (RT) were defined as cases; primary criteria for RT indication, as assessed at least 9mo postoperatively, included an uncorrected distance visual acuity (UDVA) of 20/30 or worse and a stable refraction for more than 3mo. Additional considerations included optical quality symptoms and significant higher order aberrations (HOAs). Controls were chosen from the same cohort of operated eyes which had complete post-operative follow up data beyond 9mo and did not need RT. The cohort included patients who had undergone PRK by the Tissue-Saving (TS) ablation profile of Technolas 217z100 excimer laser (Bausch & Lomb, Rochester, NY, USA). Mitomycin C had been used in all of the primary procedures. RESULTS We had 70 case eyes and 158 control eyes, and they were comparable in terms of age, sex and follow-up time (P values: 0.58, 1.00 and 0.89, respectively). Pre-operative spherical equivalent of more than -5.00 diopter (D), intended optical zone (OZ) diameter of less than 6.00 mm and ocular fixation instability during laser ablation were associated with RT indications (all P values <0.001). These factors maintained their significance in the multiple logistic regression model with odd ratios of 6.12, 6.71 and 7.89, respectively. CONCLUSION Higher refractive correction (>-5.00 D), smaller OZ (<6.00 mm) and unstable fixation during laser ablation of PRK for myopia and myopic astigmatism were found to be strong predictors of undercorrection and regression.
Collapse
Affiliation(s)
- Seyed-Farzad Mohammadi
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran 1336616351, Iran
| | - Payam Nabovati
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran 1336616351, Iran ; Department of Optometry, School of Rehabilitation, Iran University of Medical Sciences, Tehran 1676666431, Iran
| | - Ali Mirzajani
- Department of Optometry, School of Rehabilitation, Iran University of Medical Sciences, Tehran 1676666431, Iran
| | - Elham Ashrafi
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran 1336616351, Iran
| | - Banafsheh Vakilian
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran 1336616351, Iran
| |
Collapse
|
8
|
Reinstein DZ, Gobbe M, Gobbe L, Archer TJ, Carp GI. Optical Zone Centration Accuracy Using Corneal Fixation-based SMILE Compared to Eye Tracker-based Femtosecond Laser-assisted LASIK for Myopia. J Refract Surg 2015; 31:586-92. [DOI: 10.3928/1081597x-20150820-03] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 07/13/2015] [Indexed: 11/20/2022]
|
9
|
Mosquera SA, Verma S. Effects of torsional movements in refractive procedures. J Cataract Refract Surg 2015; 41:1752-66. [DOI: 10.1016/j.jcrs.2015.07.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 01/13/2015] [Accepted: 01/14/2015] [Indexed: 11/26/2022]
|
10
|
Kanellopoulos AJ, Asimellis G. LASIK ablation centration: an objective digitized assessment and comparison between two generations of an excimer laser. J Refract Surg 2015; 31:164-9. [PMID: 25751832 DOI: 10.3928/1081597x-20150225-01] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 01/08/2015] [Indexed: 11/20/2022]
Abstract
PURPOSE To objectively define the effective centration of myopic femtosecond laser-assisted LASIK ablation pattern, evaluate the difference between achieved versus planned excimer laser ablation centration, and compare these results from two different generations of an excimer laser system. METHODS The study retrospectively evaluated 280 eyes subjected to myopic LASIK. Digital image analysis was performed on Scheimpflug sagittal curvature maps (difference of preoperative to postoperative). Centration was assessed via proprietary software digital analysis of the coordinate displacement between the achieved ablation geometric center and the planned ablation center, which was the corneal vertex. Results from two different excimer laser generations (Eye-Q 400 [140 eyes] and EX500 [140 eyes]; Alcon/WaveLight, Fort Worth, TX) were compared. RESULTS Radial displacement was on average 360 ± 220 µm (range: 0 to 1,030 µm) in the Eye-Q 400 laser group and 120 ± 110 µm (range: 0 to 580 µm) in the EX500 laser group (P < .01). The percentage of eyes with displacement of greater than 300 µm was 52% in the Eye-Q 400 laser group and 4% in the EX500 laser group. CONCLUSIONS Displacement of ablation pattern may depend on the laser platform used. The improvement in the efficiency of centration indicates that newer generation excimer lasers with faster eye tracking and active centration control appear to achieve a significantly more accurate centration of myopic ablation patterns. The authors propose this novel, objective technique for laser refractive surgeon evaluation may point out significant outcome measures not currently used in standard metrics of refractive laser efficiency.
Collapse
|
11
|
Lazaridis A, Droutsas K, Sekundo W. Topographic analysis of the centration of the treatment zone after SMILE for myopia and comparison to FS-LASIK: subjective versus objective alignment. J Refract Surg 2014; 30:680-6. [PMID: 25291751 DOI: 10.3928/1081597x-20140903-04] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/25/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the centration of the treatment zone after small incision lenticule extraction (SMILE) and compare it to femtosecond laser-assisted LASIK (FS-LASIK). METHODS Sixty-nine myopic eyes of 36 patients who underwent SMILE were compared to 69 myopic eyes of 36 patients treated with FS-LASIK. All procedures were performed by a single surgeon using the VisuMax platform (Carl Zeiss Meditec, Jena, Germany). The Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) was used for preoperative and postoperative topography and pachymetry. The centration of the treatment zone was estimated pachymetrically by the distance of the thickest point on the corneal thickness differential map from the topographical center of the entrance pupil and the coaxial corneal light reflex. RESULTS In SMILE cases, the mean decentration of the lenticule from the center of the entrance pupil was 0.326 ± 0.196 mm (range: 0.014 to 1.062 mm), whereas the distribution of the lenticule centers demonstrated a nasalization pattern. In FS-LASIK cases, this value was 0.452 ± 0.224 mm (range: 0.02 to 1.040 mm), whereas the ablation centers were distributed randomly. In relation to the coaxial corneal light reflex, the decentration in SMILE was 0.315 ± 0.211 mm (range: 0.0 to 1.131 mm), whereas FS-LASIK eyes demonstrated a mean decentration of 0.516 ± 0.254 mm (range: 0.103 to 1.265 mm). The decentration from the reference point of its technique (coaxial corneal light reflex in SMILE, the entrance pupil center in FS-LASIK) was significantly more extended in the FS-LASIK group (P < .001). CONCLUSIONS The centration of the treatment zone as measured by the Pentacam was better for patient-controlled fixation during SMILE than active eye tracker-assisted FS-LASIK.
Collapse
|
12
|
Mahmoud AM, Nuñez MX, Blanco C, Koch DD, Wang L, Weikert MP, Frueh BE, Tappeiner C, Twa MD, Roberts CJ. Expanding the cone location and magnitude index to include corneal thickness and posterior surface information for the detection of keratoconus. Am J Ophthalmol 2013; 156:1102-11. [PMID: 24075426 DOI: 10.1016/j.ajo.2013.07.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 07/19/2013] [Accepted: 07/20/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE To extend the capabilities of the Cone Location and Magnitude Index algorithm to include a combination of topographic information from the anterior and posterior corneal surfaces and corneal thickness measurements to further improve our ability to correctly identify keratoconus using this new index: ConeLocationMagnitudeIndex_X. DESIGN Retrospective case-control study. METHODS Three independent data sets were analyzed: 1 development and 2 validation. The AnteriorCornealPower index was calculated to stratify the keratoconus data from mild to severe. The ConeLocationMagnitudeIndex algorithm was applied to all tomography data collected using a dual Scheimpflug-Placido-based tomographer. The ConeLocationMagnitudeIndex_X formula, resulting from analysis of the Development set, was used to determine the logistic regression model that best separates keratoconus from normal and was applied to all data sets to calculate PercentProbabilityKeratoconus_X. The sensitivity/specificity of PercentProbabilityKeratoconus_X was compared with the original PercentProbabilityKeratoconus, which only uses anterior axial data. RESULTS The AnteriorCornealPower severity distribution for the combined data sets are 136 mild, 12 moderate, and 7 severe. The logistic regression model generated for ConeLocationMagnitudeIndex_X produces complete separation for the Development set. Validation Set 1 has 1 false-negative and Validation Set 2 has 1 false-positive. The overall sensitivity/specificity results for the logistic model produced using the ConeLocationMagnitudeIndex_X algorithm are 99.4% and 99.6%, respectively. The overall sensitivity/specificity results for using the original ConeLocationMagnitudeIndex algorithm are 89.2% and 98.8%, respectively. CONCLUSIONS ConeLocationMagnitudeIndex_X provides a robust index that can detect the presence or absence of a keratoconic pattern in corneal tomography maps with improved sensitivity/specificity from the original anterior surface-only ConeLocationMagnitudeIndex algorithm.
Collapse
|
13
|
|
14
|
Arba-Mosquera S, Aslanides IM. Analysis of the effects of Eye-Tracker performance on the pulse positioning errors during refractive surgery ☆. JOURNAL OF OPTOMETRY 2012; 5:31-37. [PMCID: PMC3861148 DOI: 10.1016/j.optom.2011.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 11/13/2011] [Indexed: 05/29/2023]
Abstract
Purpose To analyze the effects of Eye-Tracker performance on the pulse positioning errors during refractive surgery. Methods A comprehensive model, which directly considers eye movements, including saccades, vestibular, optokinetic, vergence, and miniature, as well as, eye-tracker acquisition rate, eye-tracker latency time, scanner positioning time, laser firing rate, and laser trigger delay have been developed. Results Eye-tracker acquisition rates below 100 Hz correspond to pulse positioning errors above 1.5 mm. Eye-tracker latency times to about 15 ms correspond to pulse positioning errors of up to 3.5 mm. Scanner positioning times to about 9 ms correspond to pulse positioning errors of up to 2 mm. Laser firing rates faster than eye-tracker acquisition rates basically duplicate pulse-positioning errors. Laser trigger delays to about 300 μs have minor to no impact on pulse-positioning errors. Conclusions The proposed model can be used for comparison of laser systems used for ablation processes. Due to the pseudo-random nature of eye movements, positioning errors of single pulses are much larger than observed decentrations in the clinical settings. There is no single parameter that ‘alone’ minimizes the positioning error. It is the optimal combination of the several parameters that minimizes the error. The results of this analysis are important to understand the limitations of correcting very irregular ablation patterns.
Collapse
Affiliation(s)
- Samuel Arba-Mosquera
- Grupo de Investigación de Cirugía Refractiva y Calidad de Visión, Instituto de Oftalmobiología Aplicada, University of Valladolid, Valladolid, Spain
- SCHWIND Eye-tech-solutions, Kleinostheim, Germany
| | - Ioannis M. Aslanides
- Emmetropia Mediterranean Eye Clinic, Parodos Anopoleos 7, Heraklion, Crete, Greece
| |
Collapse
|