Steven H Linn

Comparative analysis of the performance of two different platforms for femtosecond laser-assisted cataract surgery

Purpose To analyze and compare the intraoperative and postoperative outcomes of cataract surgery performed with two different femtosecond laser platforms. Methods Randomized controlled prospective intraindividual comparative study including 90 eyes of 45 patients aged between 61 and 86 years. All eyes underwent bilateral cataract surgery assisted with femtosecond laser technology. Eyes were randomized to one of two different femtosecond laser platforms: Catalys Precision system (Abbott Medical Optics Inc., Santa Ana, CA, USA) (Catalys group), and LenSx system (Alcon-LenSx Inc., Aliso Viejo, CA, USA) (LenSx group). Several intraoperative parameters and changes in corrected distance visual acuity and corneal endothelial density were evaluated and compared. Results The LenSx group showed a significantly higher cumulative dissipated energy and phacoemulsification power needed compared to the Catalys group (P≤0.043). Likewise, a longer patient interface preparation time, more severe perception of pressure by patient, and more cases of subconjunctival hemorrhage were found in the LenSx group (P≤0.014). A complete capsulotomy was achieved in more cases in the Catalys group compared to the LenSx group (P=0.002). Regarding corneal incisions, no statistically significant differences were found between groups (P≥0.071). The same occurred for postoperative corrected distance visual acuity (P≥0.48), endothelial cell density changes (P≥0.14), and the incidence of corneal edema or flare (P≥0.399). Conclusion Cataract surgery with the two evaluated femtosecond laser platforms is a safe procedure, with reduced phaco time and energy, and preservation of corneal endothelium integrity. However, both systems differ in the performance of capsulotomy and the procedure of docking, with an advantage of the Catalys over the LenSx system.

Stereoacuity after small aperture corneal inlay implantation

Purpose The aim of this study was to compare stereoacuity before and after KAMRA corneal inlay implantation for the correction of presbyopia. Patients and methods This is a prospective study of 60 patients who underwent KAMRA inlay implantation. Patients were examined before and 6 months after surgery for stereoacuity, uncorrected distance visual acuity (UDVA), and uncorrected near visual acuity (UNVA). Results The mean stereoacuity before surgery was 29.5±28.1 arcsec (range: 20–200) and at 6 months was 29.8±26.4 arcsec (range: 20–200). The decline in stereoacuity was not statistically significant. At 6 months follow-up, UDVA was 20/25 or better in all 60 patients and UNVA was J2 (20/25) or better in 51 (85%) patients. Conclusion There is no significant change in stereoacuity following KAMRA inlay implantation. The KAMRA inlay is a good treatment option for improving near vision in presbyopic patients while preserving stereoacuity and distance vision.

Ectasia following small-incision lenticule extraction (SMILE): a review of the literature

Purpose Four cases of corneal ectasia after small-incision lenticule extraction (SMILE) have been reported. In this review, we provide an overview of the published literature on corneal ectasia after SMILE and risk factors associated with this complication. Methods Case reports were identified by a search of seven electronic databases for pertinent heading terms between 2011 and July 2017. We identified patient characteristics and surgical details including preoperative topography, central corneal thickness, and anterior keratometry (Km). Residual stromal bed (RSB) values not reported were computed using VisuMax ReLEx SMILE software Version 2.10.10. Preoperative ectasia risk was measured using the Randleman Ectasia Risk Score System (ERSS). Percent tissue alteration was calculated for each patient as described by Santhiago et al. Results Seven eyes of four patients developed corneal ectasia post SMILE. Two patients had abnormal topography in both eyes. One patient had abnormal topography in one eye. Only one patient was noted to have normal topography in both eyes and later developed ectasia in one eye in the absence of any known risk factors. The mean Randleman ectasia risk score was 4±3 (range: 1–8). The mean calculated percent tissue altered (PTA) was 38%±6% (range: 30%–47%). Conclusion A majority of reported ectasia cases occurred in patients with subclinical keratoconus. These conditions may be exacerbated by SMILE and should be considered absolute contraindications to the procedure. Three patients were identified to have high risk based on the ERSS, and one patient exhibited a PTA ≥40%. We formulated a modification to the current calculation of PTA that takes into account the differences in tissue altered between SMILE and laser in situ keratomileusis (LASIK). More studies are needed to fully quantify the risk of ectasia. For now, we propose adopting the same exclusion criteria used for LASIK in the SMILE procedure until more specific metrics have been validated.

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

Objective The 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 design This study followed a retrospective chart analysis. Setting This study was performed at Hoopes Vision in Draper, UT, USA. Subjects and methods Fifty-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. Results At 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. Conclusion For 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.

Comparison and analysis of FDA reported visual outcomes of the three latest platforms for LASIK: wavefront guided Visx iDesign, topography guided WaveLight Allegro Contoura, and topography guided Nidek EC-5000 CATz

Purpose To compare and analyze the differences in visual outcomes between Visx iDesign Advanced WaveScan Studio™ System, Alcon Wavelight Allegro Topolyzer and Nidek EC-5000 using Final Fit™ Custom Ablation Treatment Software from the submitted summary of safety and effectiveness of the US Food and Drug Administration (FDA) data. Methods In this retrospective comparative study, 334 eyes from Visx iDesign, 212 eyes from Alcon Contour, and 135 eyes from Nidek CATz platforms were analyzed for primary and secondary visual outcomes. These outcomes were compared via side-by-side graphical and tabular representation of the FDA data. Statistical significance was calculated when appropriate to assess differences. A P-value <0.05 was considered statistically significant. Results The mean postoperative uncorrected distance visual acuity (UDVA) at 12 months was 20/19.25±8.76, 20/16.59±5.94, and 20/19.17±4.46 for Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. In at least 90% of treated eyes at 3 months and 12 months, all three lasers showed either no change or a gain of corrected distance visual acuity (CDVA). Mesopic contrast sensitivity at 6 months showed a clinically significant increase of 41.3%, 25.1%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Photopic contrast sensitivity at 6 months showed a clinically significant increase of 19.2%, 31.9%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Conclusion FDA data for the three platforms shows all three were excellent with respect to efficacy, safety, accuracy, and stability. However, there are some differences between the platforms with certain outcome measurements. Overall, patients using all three lasers showed significant improvements in primary and secondary visual outcomes after LASIK surgery.

Short-term visual result after simultaneous photorefractive keratectomy and small-aperture cornea inlay implantation.

Purpose To report the short-term results of simultaneous photorefractive keratectomy (PRK) and small-aperture cornea inlay implantation (KAMRA) surgery in treating presbyopia. Methods Simultaneous PRK and KAMRA inlay surgery was performed on 21 patients from July 2015 to March 2016. Follow-up exams were conducted at 1, 3, and 6 months postoperatively. Our patients were also divided preoperatively into three categories: myopic, hyperopic, and emmetropic. Over the 6-month period, the main outcome measures were uncorrected near visual acuity (UNVA), changes in best-corrected distance visual acuity, and mean spherical equivalent refraction. Results At 6-month follow-up, 83% (10/12) of patients had a monocular UNVA of 20/40 or better, and 75% had a binocular UNVA of 20/40 (J5) or better. At 6 months, the overall mean refractive spherical equivalent (MRSE) was −0.60 D (±0.42 standard deviation [SD], range: −1.38 to −0.13) with a mean change of −0.43 D (±1.19 SD, range: −1.5 to 2.63) compared to preoperative data. Overall, 91% (10/11) of patients were within a ±0.5 D range of our target −0.75 D for KAMRA use. One-hundred percent (5/5) of the hyperopes, 50% (1/2) of emmetropes, and 100% (4/4) of myopes met the targeted range. At 6 months, the MRSE for the hyperopic subgroup (n=5) was 0.33 D (±0.20 SD), the MRSE for the emmetropic subgroup (n=2) was −1.19 D (±0.19 SD), and the MRSE for the myopic subgroup (n=4) was −0.66 D (±0.36 SD). Conclusion Based on preliminary results and a small sample size, it seems that simultaneous PRK and KAMRA is effective and predictable. There are multiple advantages in performing simultaneous PRK and KAMRA including a shorter recovery time and less steroid use than the two surgeries performed separately.

Initial Single-Site Surgical Experience with SMILE: A Comparison of Results to FDA SMILE, and the Earliest and Latest Generation of LASIK

IntroductionThe primary objective was to show our initial surgical single-site experience with small incision lenticule extraction (SMILE) after the official enrollment in March 2017 following Food and Drug Administration (FDA) approval for simple myopia in late 2016 in the United States and, subsequently, compare our results to the earliest and most advanced generation of excimer platforms for laser-assisted in situ keratomileusis (LASIK) surgery.MethodsThis was a retrospective single-site study of 68 eyes from 35 patients who had SMILE surgery. The patients’ preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest sphere, manifest cylinder, intraoperative complications, and preoperative and postoperative visual symptoms were collected. We compared our findings to the results from the FDA SMILE study, and to the three earliest (1999–2000) and three of the most updated (2013–2016) platforms for LASIK.ResultsThe cumulative UDVA was 20/20 and 20/40 or better in 74% and 100% of patients, respectively. The intended target refraction was within ± 0.5 and ± 1.00 D in 80% and 93% of cases, respectively. The prevalence of dry eyes decreased by nearly half from 1-week to the 6-month postoperative interval. Patients noted improvement in glare (17%), halos (17%), fluctuation (25%), and depth perception (8%) at the 6-month interval compared to preoperative levels.ConclusionsThis study’s findings are consistent with current SMILE reports. Notably, the results are superior to the earliest generation of LASIK, however inferior to the latest excimer platforms. SMILE does meet the efficacy and safety criteria met by FDA; however, there is a definite need for further improvement to reach the superior refractive outcomes produced by the latest generation of LASIK platforms.

Long-term changes in keratometry and refraction after small aperture corneal inlay implantation

Purpose To assess longitudinal refractive, keratometric, and topographic changes following KAMRA small-aperture inlay implantation. Design and setting Prospective study at a single site refractive surgery center. Methods Fifty patients underwent KAMRA small-aperture corneal inlay implantation for the correction of presbyopia. Uncorrected near visual acuity (UNVA), uncorrected distance visual acuity, manifest refractive spherical equivalent (MRSE), mean keratometry (Km), corneal topography, and surgically induced astigmatism vector analysis assessments were performed preoperatively and at 1, 3, 6, 12, 24, and 36 months postoperatively. Results The study comprises 50 eyes. An average shift of 0.15±0.63 D (range −1.63 to 2.00 D) occurred between preoperative baseline and 36 months. At 36 months, 54% of patients had hyperopic MRSE and 40% had myopic MRSE compared with baseline. Km was significantly elevated at all postoperative measurements compared with baseline, with the largest Km measured at 12 months. Eighty-six percent of patients had UNVA of 20/32 or better and 88% uncorrected distance visual acuity of 20/25 or better at 36 months. Longitudinal corneal topography revealed a pattern of corneal steepening over the body of the inlay and flattening over the aperture, correlating with a hyperopic shift. There was no significant surgically induced astigmatism. Conclusion KAMRA inlay may cause an increase in Km compared with baseline. Corneal steepening may occur in a specific pattern with steepening over the inlay and flattening over the aperture. This topographic pattern causes a hyperopic shift, which may be relevant for subsequent procedures, such as cataract extraction.

Cataract Surgery in Patients with a Previous History of KAMRA Inlay Implantation: A Case Series

IntroductionThe visual outcome of cataract surgery in patients with a previous history of KAMRA inlay implantation is an emerging issue for which limited research exists. The purpose of this study is to describe postoperative visual outcomes in this patient population.MethodsThis is a case series with retrospective chart review. Seven patients underwent cataract surgery following KAMRA corneal inlay implantation. Visual acuity was assessed before and after cataract surgery. Keratometry was measured before and after KAMRA inlay implantation, and optical biometry was performed prior to cataract surgery.ResultsPostoperatively, uncorrected distance visual acuity (UDVA) was 20/20 in five (71%) patients and 20/40 or better in seven (100%) patients, corrected distance visual acuity (CDVA) was 20/20 or better in six (86%) patients and 20/25 in seven (100%) patients, and uncorrected near visual acuity (UNVA) was J1 in four (57%) patients, J2 or better in six (86%) patients, and J3 or better in seven (100%) patients. There was no significant change in keratometry after KAMRA inlay implantation. Biometry calculations accurately predicted intraocular lens (IOL) power after cataract surgery. Surgeons did not report a significant change in the surgical technique of cataract surgery.ConclusionPatients who undergo cataract surgery with a previous history of KAMRA inlay implantation have good visual outcomes. Furthermore, intraocular lens (IOL) calculations accurately predict power, and there appears to be no significant change in surgical technique.

Neodymium:YAG laser posterior capsulotomy in eye with an intrastromal inlay

We report intraoperative issues, patient outcomes, and lessons learned from inadvertently contacting a Kamra corneal inlay with a neodymium:YAG (Nd:YAG) laser during a routine capsulotomy procedure for posterior capsule opacification. We also present scanning electron microscopic and histopathologic images from a series of 4 inlays implanted in postmortem porcine eyes that were purposely contacted with an Nd:YAG laser. Our capsulotomy patient developed a clinically insignificant and transient corneal opacity accompanied by mild blanching on the inlay. Modeling this scenario in porcine corneas demonstrated the potential for carbon particle liberation into the overlying stroma, damage to the inlay body, and fusion of inlay nutrition holes.