post-LASIK Eyes Research Articles

A Comparative Study of the Effect of Femtosecond Laser-Assisted Cataract Surgery on Corneal Astigmatism in Post-LASIK Eyes and Virgin Eyes.

To evaluate and compare the effect of femtosecond laser-assisted cataract surgery on corneal astigmatism in post-LASIK eyes and virgin eyes. Patients who underwent femtosecond laser-assisted cataract surgery were included in the study and categorized into two groups: Group A, consisting of patients with post-LASIK eyes, and Group B, consisting of patients with virgin eyes. Visual acuity, corneal astigmatism, and surgically induced astigmatism (SIA) were evaluated. Additionally, the correlation between SIA and preoperative corneal astigmatism, mean corneal curvature, and central corneal thickness was also analyzed. A total of 168 eyes were enrolled in this study, with 62 eyes in Group A and 106 eyes in Group B. Significant differences in corneal astigmatism and SIA were observed between the two groups in the early postoperative period following cataract surgery (P<0.05). However, there was no significant difference at 6 months postoperatively (P>0.05). Corneal astigmatism demonstrated an against-The-rule shift in both groups postoperatively. No significant correlation was identified between SIA and preoperative corneal astigmatism, corneal curvature or corneal thickness. Additionally, there was no significant difference observed between the two groups in terms of uncorrected distance visual acuity (UDVA) at 6 months postoperatively. The effect of femtosecond laser-assisted cataract surgery on corneal astigmatism in post-LASIK eyes and virgin eyes was different in the early postoperative period. However, there was no significant difference at 6 months postoperatively. The post-LASIK eyes exhibited a delayed recovery compared to the virgin eyes.

Computational simulation of the optical performance of an EDOF intraocular lens in post-LASIK eyes.

To evaluate computationally the optical performance of AcrySof IQ Vivity extended depth-of-focus (EDOF) intraocular lenses (IOLs) in post-laser in situ keratomileusis (LASIK) eyes. Visual Optics and Biophotonics Laboratory, Madrid, Spain. Experimental study. Computer pseudophakic eye models were implemented using reported post-LASIK corneal aberrations (refractive corrections from -7.5 to +4.5 diopters [D]) and virtually implanted with monofocal (AcrySof IQ) or EDOF (AcrySof IQ Vivity) IOLs. Retinal image quality was quantified through visual Strehl (VS). The depth of focus (DOF) was calculated from the through-focus VS curves. Halos were estimated from the light spread in the image of a pinhole. Those quantitative parameters were obtained for 5.0 and 3.0 mm pupil diameters. Simulated virgin eyes showed VS of 0.89/0.99 with monofocal IOLs and 0.74/0.52 with EDOF IOLs for 5.0/3.0 mm pupils at best focus. VS decreased with induced spherical aberration (SA) by 25% and with induced SA + coma by 61% on average (3.0 mm pupils). The DOF was 2.50 D in virgin eyes with EDOF IOLs, 1.66 ± 0.30 and 2.54 ± 0.31 D ( P < .05) on average in post-LASIK eyes for 3.0 mm pupils, monofocal and EDOF IOLs, respectively. Halos were more sensitive to SA induction for 5.0 mm pupils, and induction of positive SA (myopic LASIK) resulted in reduced halos with the EDOF when compared with the monofocal IOLs, by 1.62 (SA) and 1.86 arc min (SA + coma), on average. Computer post-LASIK pseudophakic eye models showed that the DOF was less dependent on the presence of SA and coma with EDOF IOLs and that halos were reduced with EDOF IOLs compared with the monofocal IOL for a range of SA.

Patient Satisfaction, Visual Outcomes, and Regression Analysis in Post-LASIK Patients Implanted With Multifocal, EDOF, or Monofocal IOLs.

To compare and contrast functional visual outcomes and levels of patient satisfaction in post-laser in situ keratomileusis (LASIK) cataract patients with multifocal, extended depth of focus (EDOF), or monofocal intraocular lens (IOLs). Three cohorts of post-LASIK eyes with multifocal, EDOF, or monofocal IOLs were evaluated. Objective preoperative and postoperative clinical metrics, including higher-order aberration, contrast sensitivity, and visual acuities, plus subjective responses to a questionnaire about satisfaction, spectacle use, and ability to perform tasks were compared. Variables were regressed against "overall patient satisfaction" to identify predictors of satisfaction. Ninety-seven percent of patients were "very satisfied" or "satisfied." "Very satisfied" was significantly greater in multifocal (86.8%, 33 of 38) and EDOF (72.7%, 8 of 11) vs. monofocal (33.3%, 6 of 18) IOLs. However, EDOF IOLs outperformed monofocal IOLs for intermediate ( P =0.04). Contrast sensitivity was significantly worse at distance for multifocal vs. both EDOF ( P =0.05) and monofocal ( P =0.005) IOLs. Regression revealed that greater patient satisfaction in multifocal was explained by near visual function variables, including UNVA ( P =0.001) and UIVA ( P =0.04), reading acuity ( P =0.014), reading speed ( P =0.05), spectacle use at near ( P =0.0014), and ability to read moderate print ( P =0.002). Multifocals achieved high satisfaction levels in post-LASIK patients despite higher-order aberrations and lower contrast sensitivity scores; regression revealed that uncorrected near visual function variables explained high levels of satisfaction; dysphotopsias did not contribute significantly to scores for satisfaction; multifocal IOLs are a viable choice for cataract patients who have previously undergone LASIK.

Comparison of surgically induced astigmatic changes after cataract surgery in post-Laser in situ keratomileusis corneas versus virgin eyes.

Postoperative refraction in modern mi-croincision cataract surgery gained extra importance in patients with the previous laser-assisted in situ keratomileusis (LASIK) surgery. The surgically induced astigmatic changes in those eyes may differ not only in magnitude but also in direction compared to virgin corneas. This study aimed to compare the surgically induced astigmatic changes after microscopic cataract surgery between post-LASIK corneas and virgin eyes. Cases that underwent microincision cataract surgery in eyes with and without previous LASIK surgery were reviewed. The demographics, the axial length at cataract surgery, the central corneal thickness, spheric and cylindric values, keratometry readings, and postoperative posterior corneal astigmatism were retrospectively evaluated. A modified Alpins method was used for astigmatic vector analysis, and baseline astigmatism, surgically induced astigmatism, difference vector, flattening effect, and torque were assessed. A total of 42 eyes from 24 subjects was evaluated. Group I consisted of 14 eyes with the previous LASIK, and Group II included 28 eyes without any refractive surgery. Preoperative mean central corneal thickness in Group I was significantly thinner (p=0.012). There was no significant difference in baseline astigmatism between the groups regarding magnitude and power vectors. After microincision cataract surgery, there were no significant differences in mean spheric and cylindric values and mean keratometry readings (all p>0.05). However, surgically induced astigmatism and difference vector were significantly higher on J45 vector component in post-LASIK eyes and microincision cataract surgery steepening effect on post-LASIK corneas was significantly higher than those in virgin eyes (p=0.001, p=0.002 and p=0.018, respectively). Cataract surgery has steepened the corneas in both groups with a significantly higher steepening effect in post-LASIK eyes. Certainly, corneal topography cataract surgery is particularly helpful to provide more precise surgically induced astigmatism interpretations.

Refractive Outcomes Following Trifocal Intraocular Lens Implantation in Post-Myopic LASIK and PRK Eyes.

PurposeTo assess refractive outcomes of a trifocal intraocular lens (IOL) in post-myopic laser refractive surgery eyes.MethodsThis was a retrospective chart review of 35 eyes (21 patients), with history of laser refractive surgery, who were implanted with a trifocal IOL. Surgeon’s standard procedure included femtosecond laser (FLACS), digital registration, and intraoperative aberrometry (IA). The primary outcome measure was absolute prediction error. Secondary measures were refractive outcomes, postoperative residual astigmatism (PRA), monocular uncorrected visual acuity at distance (UDVA; 4m), intermediate (UIVA; 60cm), and near (UNVA; 40cm), and monocular best-corrected visual acuity at distance (BCVA; 4m).ResultsAt 3 months postoperatively, 71% and 68% of eyes had absolute prediction error 0.5 D or less with IA and preoperative planning respectively, which was not statistically significant (p > 0.05). The PRA was 0.5 D or less in 91% of eyes with IA and 56% of eyes with preoperative planning. The PRA differences between IA and preoperative planning were statistically significant (p < 0.002). The percentage of eyes 20/20 or better for monocular UCVA, BCVA, UIVA, and UNVA was 29%, 77%, 78%, and 66%, respectively. Absolute prediction error 0.5 D or less was significantly higher in post-LASIK eyes versus post-PRK eyes (p < 0.003), at 85% and 56% of eyes, respectively.ConclusionImplantation with a trifocal IOL can provide acceptable refractive and visual outcomes with minimal residual astigmatism in post-myopic LASIK and PRK eyes.

RETRACTED ARTICLE: Posterior chamber phakic intraocular lens implantation after laser in situ keratomileusis

BackgroundTo assess the multicenter outcomes of posterior chamber phakic intraocular lens implantation with a central hole (EVO-ICL, STAAR Surgical) for patients undergoing previous laser in situ keratomileusis (LASIK).MethodsThis case series enrolled 31 eyes of 21 consecutive patients undergoing EVO-ICL implantation to correct residual refractive errors after LASIK at 7 nationwide major surgical sites. We investigated safety, efficacy, predictability, stability, and adverse events at 1 week, 1, 3, and 6 months postoperatively, and at the final visit.ResultsThe mean observation period was 1.6 ± 1.8 years. Uncorrected and corrected visual acuities were − 0.14 ± 0.11 and − 0.22 ± 0.09 logMAR at 6 months postoperatively. At 6 months postoperatively, 81% and 100% of eyes were within ± 0.5 D and ± 1.0 D, respectively, of the targeted correction. We found neither significant manifest refraction changes of 0.05 ± 0.38 D from 1 week to 6 months nor apparent intraoperative or postoperative complications in any case.ConclusionsOur multicenter study confirmed that the EVO-ICL provided good outcomes in safety, efficacy, predictability, and stability, even in post-LASIK eyes. Therefore, EVO-ICL implantation may be a viable surgical option, even for correcting residual refractive errors after LASIK.Trial registration University Hospital Medical Information Network Clinical Trial Registry (000045295).

Refractive Errors after Cataract Surgery Using Total Keratometry in Post-LASIK Eyes

Refractive Errors after Cataract Surgery Using Total Keratometry in Post-LASIK Eyes

Dry Eyes Post Laser Assisted in Situ Keratomileusis

Dry eye is one of the most common complications following laser-assisted in situ keratomileusis (LASIK), with nearly all patients experiencing some degree of postoperative dry eye symptoms. Postoperative dry eye affects approximately 50% of patients at 1 week postoperatively, 40% at 1 month, and 20%-40% at 6 months postoperatively. LASIK can cause intracorneal nerve damage, goblet cell damage caused by suction, and can cause changes in the shape of the central cornea. Dry eye diagnosis can be made using a questionnaire to determine the patient's history, examination of tear break up time, staining of the eye surface using fluorescein or lissamine green, and Schirmer's test. This reserech use Literatur Review Method. Post-LASIK dry eye complaints such as irritation, red eyes, foreign body sensation, pain, gritty, and photophobia. Management of post-LASIK dry eyes can be done by giving tear supplements, anti-inflammatory agents, ointments and eye patches, and treatment of meibomian gland dysfunction. Post-LASIK dry eye usually peaks within a few months after surgery, and then improves in most patients 6-12 months after surgery. Although dry eye signs and symptoms are most common in the immediate postoperative period and are usually only temporary, a minority of individuals experience chronic and severe dry eye

Comparison of tear proteomic and neuromediator profiles changes between small incision lenticule extraction (SMILE) and femtosecond laser-assisted in-situ keratomileusis (LASIK)

IntroductionThe tear proteomics and neuromediators are associated with clinical dry eye parameters following refractive surgery. PurposeTo investigate and compare the tear proteomic and neuromediator profiles following small incision lenticule extraction (SMILE) versus laser-assisted in-situ keratomileusis (LASIK). MethodsIn this randomized controlled trial with paired-eye design, 70 patients were randomized to receive SMILE in one eye and LASIK in the other eye. Tear samples were collected preoperatively, and 1 week, 1, 3, 6 and 12 months postoperatively, and were examined for protein concentration changes using sequential window acquisition of all theoretical fragment ion mass spectrometry (SWATH-MS). The data were analyzed with DAVID Bioinformatics Resources for enriched gene ontology terms and over-represented pathways. Tear neuromediators levels were correlated with clinical parameters. ResultsPost-SMILE eyes had significantly better Oxford staining scores and tear break-up time (TBUT) than post-LASIK eyes at 1 and 3 months, respectively. Tear substance P and nerve growth factor levels were significantly higher in the LASIK group for 3 months and 1 year, respectively. SMILE and LASIK shared some similar biological responses postoperatively, but there was significant up-regulation in leukocyte migration and wound healing at 1 week, humoral immune response and apoptosis at 1 month, negative regulation of endopeptidase activity at 3 to 6 months, and extracellular structure organization at 1 year in the post-LASIK eyes. Tear mucin-like protein 1 and substance P levels were significantly correlated with TBUT (r = -0.47, r = -0.49, respectively). ConclusionSignificant differences in the tear neuromediators and proteomics were observed between SMILE and LASIK, even though clinical dry eye signs have subsided and became comparable between 2 procedures.

Cataract surgery after myopic laser in situ keratomileusis: objective analysis to determine best formula and keratometry to use.

To objectively determine which formula/keratometry combination was best for calculating intraocular lens (IOL) sphere power in eyes with a history of myopic laser in situ keratomileusis (LASIK). One practice in the United States. Retrospective, unmasked, nonrandomized chart review. Consecutive patients undergoing cataract surgery after previous myopic LASIK were included. Eyes had to have a postoperative refraction at least 3 weeks postoperatively. IOL power was calculated with the ASCRS online postrefractive IOL calculator using anterior keratometry and recalculated using total corneal power (TK). The accuracy of treatment was calculated and compared between different formulas and keratometry methods including intraoperative aberrometry (IA). Data from 101 eyes, 44 of which had TK available, were analyzed. Using TK, the Wang-Koch-Maloney formula had the highest percentages of eyes with expected spherical equivalent refractive errors within 0.50 diopter (D) and 1.00 D of plano (57% and 87%, respectively). With anterior keratometry, the Barrett True-K formula had the highest percentages (64% and 92%, respectively) but was not significantly better than the Wang-Koch-Maloney formula, with expected errors within ±0.50 and ±1.00 D (P > .2, McNemar test). Expected sphere results based on IA were not significantly different than for Barrett True-K within ±0.50 D or within ±1.00 D (P > .2, McNemar test). Using TK in existing post-LASIK formulas did not seem beneficial. The formulas might have to be optimized for use with TK. The best expected results were obtained with the Barrett True-K and Haigis-L formulas using anterior keratometry. IA did not seem to materially improve results.

Comparison of intraocular lens calculation methods after myopic laser-assisted in situ keratomileusis and radial keratotomy without prior refractive data

AimTo compare intraocular lens (IOL) calculation methods not requiring refraction data prior to myopic laser-assisted in situ keratomileusis (LASIK) and radial keratotomy (RK).MethodsIn post-LASIK eyes, the methods not requiring prior...

Reduction of corneal epithelial thickness during medical treatment for myopic regression following FS-LASIK

BackgroundTo evaluate corneal epithelial thickness change during medical treatment for eyes with myopic regression after femtosecond laser-assisted in situ keratomileusis (FS-LASIK).MethodsThis study included 84 eyes of 54 subjects diagnosed with myopic regression after FS-LASIK and treated using topical steroid and anti-glaucoma drugs. Corneal epithelial thickness was measured using Fourier-domain optical coherence tomography before and after treatment. Subjects were divided into three groups based on their corneal epithelial thickness at the time of myopic regression and regression analyses were used to investigate the association between corneal epithelial thickness, visual acuity, and refraction. Logistic regression and receiver operating characteristic (ROC) curve analysis was performed to determine whether corneal epithelial thickness could predict the success of treatment, improvements of ≥ two lines in uncorrected distance visual acuity and ≥ 0.5 diopter in refraction or K.ResultsCorneal epithelial thickness decreased with greater change in the center as myopic regression subsided during medical treatment. Subgroup with the thickest epithelium (≥ 62 μm) showed a higher success rate and greater changes in refraction and vision. Reduced magnitude of corneal epithelial thickness showed significant correlations with changes of K and refractive error (all P < 0.001). Corneal epithelial thickness was a significant factor for the success of treatment and ROC curve showed that corneal epithelial thickness > 60.50 μm had 81.5% sensitivity and 84.2% specificity for the success of medical treatment.ConclusionCorneal epithelial thickness decreases proportionally with the magnitude of improvement of myopic regression during treatment with steroid and anti-glaucoma drugs in post-LASIK eyes with myopic regression.

Comparison of central corneal thickness measurement by scanning slit topography, infrared, and ultrasound pachymetry in normal and post-LASIK eyes.

To compare central corneal thickness (CCT) measurements by scanning slit topography (SST), infrared pachymetry (IRP), and ultrasound pachymetry (USP), and their agreement in normal and post-laser in situ keratomileusis (LASIK) eyes. Sixty normal and 35 post-LASIK subjects were recruited. Only one eye from each subject was analyzed. Non-contact pachymetry was performed first, and the order for SST (Orbscan IIz) and IRP (Tonoref III) was randomized for each patient, to be followed by contact USP (Echoscan US-4000). Pearson's correlation, paired t test, and Bland-Altman plots were used to investigate association, difference, and agreement among different instruments respectively. The measurements obtained with the instruments were highly correlated. Compared to CCT determined by USP (CCTUSP), CCT determined by SST (after correction with acoustic factor) (CCTSSTC) was thicker by 7µm in normal eyes (P < 0.001). There was no significant difference between CCTSSTC and CCTUSP (P = 0.128), but a thickness-dependent deviation in post-LASIK eyes (P = 0.003). The CCT determined by IRP (CCTIRP) was thicker than CCTUSP in normal (P < 0.001) and post-LASIK eyes (P < 0.001) and demonstrated proportional overestimation with thinner corneas, with less predictable ultrasonic equivalent corneal thickness in normal eyes. Conversely, CCTIRP significantly underestimated CCT compared to CCTSST and showed increasing underestimation with thinner corneas in both normal and post-LASIK eyes (both P < 0.001). Central corneal thickness determined by SST, IRP and USP were not interchangeable or interconvertible, probably attributed to difference in methodologies. Compensation with algorithms may improve agreements amongst instruments.

Corneal Biomechanical Parameters With Corneoscleral Contact Lenses in Post-Laser In Situ Keratomileusis Eyes.

To evaluate corneal biomechanical parameters wearing corneoscleral contact lenses (CScL) in patients with irregular corneas after laser in situ keratomileusis (LASIK). Data from patients fitted with CScL because of corneal surface irregularities after complicated LASIK surgery were selected by two eye clinics. Previously and after 1 year of CScL fitting, corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc), and central corneal thickness were evaluated. In addition, visual acuity, subjective comfort, and wearing time CScL were reported. The study comprised 27 eyes. Statistically significant differences were found in visual acuity between the best spectacle-corrected vision and after CScL fitting [mean±SD, 0.16±0.03 logarithm of the minimum angle of resolution (logMAR) and 0.01±0.06 logMAR, respectively; P<0.001]. In addition, the patients reported high subjective comfort ratings (22 eyes were comfortable or very comfortable) and prolonged usage times (mean±SD, 12.67±1.98 hr of continuous wear a day). Statistically significant differences were found in the CRF between before CScL fitting and after 1 year of CScL wear (mean±SD, 7.57±0.87 and 7.68±0.84 mm Hg, respectively; P=0.015). Central corneal thickness, CH, and IOPcc showed slight differences after 1 year of CScL wear (1.78 μm, 0.04 and 0.21 mm Hg, respectively). Corneal biomechanical parameters increased slightly, although significantly for CRF, apparently without adverse clinical effects in post-LASIK eyes with irregular corneas after wearing CScL for 1 year.

Femtosecond laser-assisted cataract surgery with implantation of a diffractive trifocal intraocular lens after laser in situ keratomileusis: a case report

BackgroundWe report for the first time, a case of femtosecond laser-assisted cataract surgery (FLACS) with implantation of a diffractive trifocal intraocular lens (IOL) after laser in situ keratomileusis (LASIK).Case presentationA 60-year-old man underwent FLACS uneventfully 15 years after myopic LASIK. An AT Lisa tri 839MP IOL was implanted with the expectation of spectacle independence. The Haigis-L formula was chosen for calculation of the IOL power and it provided reliable results. Three months postoperatively, the uncorrected visual acuities were 0.00 logMAR for distance, 0.10 logMAR for intermediate, and 0.10 logMAR for near.ConclusionsThis case suggested that FLACS presents a feasible surgical technique for post-LASIK eyes and that implantation of trifocal IOL can achieve good visual performance in strictly selected cases after myopic LASIK.

Reducing starbursts in highly aberrated eyes with pupil miosis.

To test the hypothesis that marginal ray deviations determine perceived starburst sizes, and to explore different strategies for decreasing starburst size in highly aberrated eyes. Perceived size of starburst images and visual acuities were measured psychophysically for eyes with varying levels of spherical aberration, pupil sizes, and defocus. Computationally, we use a polychromatic eye model including the typical levels of higher order aberrations (HOAs) for keratoconic and post-LASIK eyes to quantify the image quality (the visually weighted Strehl ratio derived from the optical transfer function, VSOTF) with different pupil sizes at both photopic and mesopic light levels. For distance corrected post-LASIK and keratoconic eyes with a night-time pupil (e.g., 7mm), the starburst diameter is about 1.5 degrees (1 degree for normal presbyopic eyes), which can be reduced to ≤0.25 degrees with pupil sizes ≤3mm. Starburst size is predicted from the magnitude of the longitudinal spherical aberration. Refracting the eye to focus the pupil margin also removed starbursts, but, unlike small pupils, significantly degraded visual acuity. Reducing pupil diameter to 3mm improved image quality for these highly aberrated eyes by about 2.7× to 1.7× relative to the natural pupils when light levels were varied from 0.1 to 1000cdm-2 , respectively. Subjects with highly aberrated eyes observed larger starbursts around bright lights at night predictable by the deviated marginal rays. These were effectively attenuated by reducing pupil diameters to ≤3mm, which did not cause a drop in visual acuity or modelled image quality even at mesopic light levels.

Placido disk-based topography versus high-resolution rotating Scheimpflug camera for corneal power measurements in keratoconic and post-LASIK eyes: reliability and agreement

To compare the repeatability/reproducibility of measurement by high-resolution Placido disk-based topography with that of a high-resolution rotating Scheimpflug camera and assess the agreement between the two instruments in measuring corneal power in eyes with keratoconus and post-laser in situ keratomileusis (LASIK). One eye each of 36 keratoconic patients and 20 subjects who had undergone LASIK was included in this prospective observational study. Two independent examiners worked in a random order to take three measurements of each eye with both instruments. Four parameters were measured on the anterior cornea: steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism (Ks-Kf). Intra-examiner repeatability and inter-examiner reproducibility were evaluated by calculating the within-subject standard deviation (Sw) the coefficient of repeatability (R), the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC). Agreement between instruments was tested with the Bland-Altman method by calculating the 95% limits of agreement (95% LoA). In keratoconic eyes, the intra-examiner and inter-examiner ICC were >0.95. As compared with measurement by high-resolution Placido disk-based topography, the intra-examiner R of the high-resolution rotating Scheimpflug camera was lower for Kf (0.32 vs 0.88), Ks (0.61 vs 0.88), and Km (0.32 vs 0.84) but higher for Ks-Kf (0.70 vs 0.57). Inter-examiner R values were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The 95% LoA were -1.28 to +0.55 for Kf, -1.36 to +0.99 for Ks, -1.08 to +0.50 for Km, and -1.11 to +1.48 for Ks-Kf. In the post-LASIK eyes, the intra-examiner and inter-examiner ICC were >0.87 for all parameters. The intra-examiner and inter-examiner R were lower for all parameters measured using the high-resolution rotating Scheimpflug camera. The intra-examiner R was 0.17 vs 0.88 for Kf, 0.21 vs 0.88 for Ks, 0.17 vs 0.86 for Km, and 0.28 vs 0.33 for Ks-Kf. The inter-examiner R was 0.09 vs 0.64 for Kf, 0.15 vs 0.56 for Ks, 0.09 vs 0.59 for Km, and 0.18 vs 0.23 for Ks-Kf. The 95% LoA were -0.54 to +0.58 for Kf, -0.51 to +0.53 for Ks and Km, and -0.28 to +0.27 for Ks-Kf. As compared with Placido disk-based topography, the high-resolution rotating Scheimpflug camera provides more repeatable and reproducible measurements of Ks, Kf and Ks in keratoconic and post-LASIK eyes. Agreement between instruments is fair in keratoconus and very good in post-LASIK eyes.

Six-month visual outcomes for the correction of presbyopia using a small-aperture corneal inlay: single-site experience.

ObjectiveThe objective of this study was to describe 6-month postoperative efficacy and safety outcomes after monocular KAMRA corneal inlay implantation in emmetropic presbyopic patients.Study designThis study followed a retrospective chart analysis.SettingThis study was performed at Hoopes Vision in Draper, UT, USA.Subjects and methodsFifty-seven patients met the inclusion criteria of this study and underwent KAMRA corneal inlay implantation following the approval of the United States Food and Drug Association between May 2015 and April 2016 at a single site. Surgery involved femtosecond laser-created corneal pockets of various depths. Efficacy, safety, and patient satisfaction reports were analyzed at 3 and 6 months.ResultsAt 6 months follow-up, the monocular uncorrected near visual acuity (UNVA) was Jaeger (J) 4 (20/32), the mean uncorrected distance visual acuity was 20/25, and the mean corrected distance visual acuity was 20/20. At 6 months, 71% of patients with a pocket depth of ≥250 μm had a UNVA of 20/20 or better, whereas only 22% of patients with a shallow pocket depth of <250 μm had a UNVA of 20/20 or better. There was no statistical difference in UNVA at 6 months between virgin eyes and post-LASIK eyes. One patient had an explant and five patients underwent inlay recentration, all of which resulted in improved visual acuity. At 6 months, 72% of patients reported some level of satisfaction, 26% of patients reported being “not dependent” on reading glasses, and 62% of patients reported being able to do most things in bright light without reading glasses.ConclusionFor patients with emmetropic presbyopia, the KAMRA inlay is a viable treatment option resulting in improved UNVA. Increased pocket depth may be associated with better postoperative outcomes. Safety rates are high, while explantation and recentering rates are low. Overall, patient satisfaction of the KAMRA inlay is good.

Long term changes of posterior corneal elevation after myopic laser in situ keratomileusis

Background: Corneal ectasia is a serious complication after laser in situ keratomileusis (LASIK). Ideally, patients at risk of ectasia should be identified prior to laser as unsuitable for LASIK, however, at present, there is no absolute test, system, or marker that can unequivocally identify patients at risk of developing ectasia. It has been suggested that changes in the forward protrusion of the posterior cornea or posterior corneal elevation (PCE) may be a key to the early detection of ectasia after LASIK. The purpose of this study was to examine the long term changes of the PCE after myopic LASIK using the ORBSCAN ® IIz (Bausch & Lomb, Rochester, USA) and to evaluate the contributory preoperative factors to PCE changes. Methods: This was a retrospective longitudinal case series. Forty-two eyes of 23 consecutive myopic patients who underwent uneventful LASIK surgery 6 years ago were recalled for a postoperative follow-up examination using the ORBSCAN ® IIz to determine the elevation changes to the posterior corneal surface from the preoperative measurements. A forward shift of the posterior surface was given a negative value. Correlation analyses and forward stepwise regression analyses were performed to evaluate the effect of each of the preoperative parameters on the changes in PCE. Statistical and graphical analyses were performed. Results: There was no statistical difference between the mean best-fit sphere (BFS) pre-LASIK and 6 years postop (P=0.25). Forty-two post-LASIK eyes had a mean posterior displacement of −9.38±9.84 µm (range, 12 to −31 µm) 6 years after LASIK. Forward stepwise multiple linear regression analysis indicated that the ablation spherical equivalent (ASE) was the only indicator of the forward shift of the posterior cornea after LASIK. Conclusions: The present study identified a significant forward shift of the posterior cornea 6 years after LASIK. The ASE was the most significant prognostic determinant for forward protrusion of the posterior cornea after LASIK.

Evaluation of Equivalent Keratometry Readings Obtained by Pentacam HR (High Resolution).

PurposeTo assess the repeatability of Equivalent Keratometry Readings (EKRs) obtained by the Pentacam HR (high resolution) in untreated and post-LASIK eyes, and to compare them with the keratometry (K) values obtained by other algorithms.MethodsIn this prospective study, 100 untreated eyes and 71 post-LASIK eyes were included. In the untreated group, each eye received 3 consecutive scans using the Pentacam HR, and EKR values in all central corneal zone, the true net power (Knet) and the simulated K (SimK) were obtained for each scan. In the post-LASIK group, each eye received subjective refraction and 3 consecutive scans with the Pentacam HR preoperatively. During the 3-month post-surgery exam, the same examinations and the use of an IOLMaster were conducted for each eye. The EKRs in all zone, the Knet, the mean K (Km) by IOLMaster and the K values by clinical history method (KCHM) were obtained. The repeatability of the EKRs was assessed by the within-subject standard deviation (Sw), 2.77Sw, coefficient of variation (CVw) and intraclass correlation coefficient (ICC). The bonferroni corrected multiple comparisons were performed to analyze the differences among the EKRs and K values calculated by other algorithms within the 2 groups. The 95% limits of agreement (LoA) were calculated.ResultsThe EKR values in all central corneal zone were repeatable in both the untreated group (Sw≦0.19 D, 2.77Sw≦0.52 D, CVw≦1%, ICC≧0.978) and the post-LASIK group (Sw≦0.22 D, 2.77Sw≦0.62 D, CVw≦1%, ICC≧0.980). In the untreated group, the EKR in 4mm zone was close to SimK (P = 1.000), and the 95% LoA was (-0.13 to 0.15 D). The difference between Knet and SimK was -1.30±0.13 D (95% LoA -1.55 to -1.55 D, P<0.001). In the post-LASIK group, all the EKRs were significantly higher than KCHM (all P<0.001). The differences between the EKR in 4mm zone and KCHM, the EKR in 7mm zone and KCHM, Knet and KCHM, Km and KCHM, SimK and Knet were 0.64±0.50 D (95% LoA, -0.33 to 1.62 D), 1.77±0.88 D (95% LoA, 0.04 to 3.51 D), -0.98±0.48 D (95% LoA, -1.92 to -0.04 D), 0.64±0.53 D (95% LoA, -0.40 to 1.68 D), and 1.73±0.20 D (95% LoA, 1.33 to 2.13 D), respectively.ConclusionsThe EKRs obtained by the Pentacam HR were repeatable in both untreated eyes and post-LASIK eyes. Compared to the total corneal power obtained by the clinical history method, the EKR values generally overestimated the total corneal power in post-LASIK eyes. So, further calibrations for the EKR values should be conducted, before they were used for the total corneal power assessment in post-LASIK eyes.