Customized eye modeling for optical quality assessment in myopic femto-LASIK surgery.

Refractive surgery is recognized as an effective method for myopia treatment, but it can induce night vision disturbances such as glare. We present an eye modeling method for the optical quality assessment in response to the structural changes in the eyes by femto-LASIK surgery. Customized eye models were built from the measurements of 134 right eyes pre- and post-operatively. Optical performance was evaluated using spot diagrams, point spread functions (PSFs), modulation transfer functions (MTFs), and chromatic aberrations at various fields (0°-30°), different pupil diameters (2-6 mm), and initial myopias (- 1.25 to - 10.5 D). Pupil size and initial myopia are the two major factors that affect visual performance of post-operative eyes. The results of spot diagrams, PSFs, and MTFs indicated that post-operative visual performance deteriorated as the visual field and pupil size increased, and it was significantly influenced by initial myopia. Post-operative chromatic aberrations were also affected by initial myopia. As pupil size increased, the post-operative longitudinal chromatic aberrations tended to decrease slightly, while the transverse chromatic aberrations remained similar. The use of eye modeling for refractive surgery assessment could possibly provide a more personalized surgical approach, could improve the prediction accuracy of refractive surgery outcomes, and promote the invention and development of better surgical methods.

The combination of excimer laser ablation and drug eluting balloon for treating superficial femoral arterial occlusion following stent implantation: A case report.

RATIONALE: Recent research shows that in-stent restenosis (ISR) occurs in half of the patients treated with stenting of femoral and popliteal artery for lower extremity arteriosclerotic occlusive disease (LEASO). Combined therapy is mainly used clinically to obtain better medium- and long-term treatment outcomes and reduce the occurrences of reintervention, among which, the combination of excimer laser ablation (ELA) and drug eluting balloon (DEB) is a new and effective choice. PATIENT CONCERNS: A 76-year-old male patient with ISR of right superficial femoral artery after stent implantation was reported. DIAGNOSIS: Rechecking angiography indicated severe occlusion of the right superficial femoral artery. The physical examination showed that bilateral femoral and popliteal arteries were accessible whereas right dorsalis and posterior tibial arteries are unaccessible. Ankleolus brachial index (ABI) was 0.92 for left and 0.58 for right. INTERVENTIONS: We performed the operation with ELA and drug balloon DEB on the right superficial femoral artery under local anesthesia and treated with oral antiplatelet drugs after operation. OUTCOMES: The combination treatment was very successful, and postoperative lower extremity arteriogram showed the blood flow was fluent and fast. No recurrence was discovered 3 months after the operation and he had no obvious symptom of claudication. LESSONS: The combination of ELA and DEB is useful and effective for ISR of peripheral vessel after stent implantation, and this surgical method is worthwhile but need further clinical research for safety confirmation.

Feasibility of the new sutureless excimer laser-assisted non-occlusive anastomosis clip in a rabbit model.

BACKGROUND: The excimer laser-assisted non-occlusive anastomosis (ELANA) technique facilitates the construction of anastomoses without temporary occlusion of the recipient artery. Experiments aimed at simplifying the technique eventually resulted in a sutureless ELANA slide (SEsl) anastomosis. After the first clinical use, new insights lead to the application of a clip at the back of the device, the SELANA clip (SEcl). The SEcl offers a distinct advantage over the SEsl since no sealant is necessary. In this study, we determine the feasibility of the SEcl anastomosis in an in vivo rabbit model. METHODS: 15 SEcl anastomoses and 15 conventional ELANA anastomoses were created on the abdominal aorta in 5 rabbits. Mean application times, flap retrieval rates, hemostasis, and burst pressures were assessed. RESULTS: The mean application time of the SEcl anastomoses was 11.4 min versus 39.0 min for the ELANA anastomoses (mean difference, 27.6 min; 95% CI, 20.6-34.7). The flap retrieval rate of the SEcl anastomoses (14/15) was not inferior to the flap retrieval rate of the ELANA anastomoses (13/15). Direct hemostasis was achieved in 13/15 (87%) SEcl anastomoses and in 14/15 (94%) ELANA anastomoses. All SEcl anastomoses were resistant to provoked pressures until 250 mmHg. CONCLUSION: The SEcl anastomosis is technically feasible in in vivo experiments. Mean application time, flap retrieval rate, hemostasis, and burst pressure are not inferior to the conventional ELANA anastomosis. Further long term experiments should be performed to assess safety, patency, and reendothelialization.

Corneal power changes with Scheimpflug rotating camera after hyperopic LASIK.

To evaluate surgically induced refractive change (SIRC) by manifest refraction and corneal power changes using an automated keratometer and Scheimpflug rotating camera, and to find the best keratometric measurements reflecting SIRC after hyperopic laser-assisted in situ keratomileusis (LASIK).This retrospective study included 18 eyes of 18 patients undergoing hyperopic LASIK using the Schwind Amaris 750S excimer laser. All measurements were performed preoperatively and 12 months postoperatively. Cycloplegic manifest refractions were performed and keratometric measurements were obtained via an RK-5 automated keratometer and a Pentacam rotating Scheimpflug camera. Sim K, true net power (TNP), and total corneal refractive power (TCRP) at 2.0 to 5.0 mm were analyzed using a Scheimpflug camera.The mean manifest refractive changes in the spherical equivalent (SE) at the corneal plane were 2.32 ±â€Š1.65 D at 12 months postoperatively. The refractive power changes by the automated keratometer and Sim K were significantly less than SIRC (P = .043 and P = .048, respectively). Both TNP and the TCRP in the 5.0 mm zone produced lesser mean differences with SIRC (0.05 D and 0.06 D) and showed closer agreements with SIRC on Bland-Altman plots and higher correlation coefficients with SIRC.Corneal power measured on the anterior corneal surface underestimated SIRC. TCRP at the 5.0 mm zone provided by a Pentacam Scheimpflug camera reflected the SIRC accurately and precisely, and would be applicable for prediction of intraocular power before cataract surgery and follow-up measurement of corneal refractive power.

[Advocating standardization and customization of corneal refractive surgery in Chinese domestic situation].

With the improvement and application of excimer laser and femtosecond laser equipment in clinical ophthalmology, the diversified strategies for corneal refractive surgery candidates have been provided. Based on the trend of " all-laser treatment", it is very necessary to take the domestic situation into consideration when a standard and customized choice is made according to the indications of each specific surgical type. The characteristics and limitations of various surgeries are elucidated and commented here in order to provide some reasonable treatment options for refractive surgery. (Chin J Ophthalmol, 2016, 52: 481-485).

Ultraviolet B Phototherapy for Psoriasis: Review of Practical Guidelines.

Psoriasis is an inflammatory skin condition that affects approximately 2 % of people worldwide. Topical treatments, systemic treatments, biologic agents, and phototherapy are all treatment options for psoriasis. Ultraviolet (UV) B phototherapy is most appropriate for patients with >10 % affected body surface area who have not responded to topical treatments. This review outlines the use, dosage, safety, and efficacy of narrowband UVB (NB-UVB) and targeted phototherapy. NB-UVB and excimer laser are effective treatment options for psoriasis; they are administered two to three times weekly until clearance followed by maintenance treatment before discontinuation. Long-term data on NB-UVB indicate that it has a good safety profile. NB-UVB is commonly used with adjunctive topical treatments such as emollients, calcipotriene, cortico-steroids, retinoids, and tar. NB-UVB can be used in selected patients with traditional systemic agents such as methotrexate, mycophenolate mofetil, and cyclosporine, although the duration of the combined treatment should be kept to a minimum and patients need to be closely monitored. Acitretin can be safely used with phototherapy, but robust data on the combination use of biologic agents or phosphodiesterase inhibitors with phototherapy are lacking.

Standardization of laser in situ keratomileusis surgical technique evaluated by comparison of procedure time between 2 experienced surgeons.

PURPOSE: To evaluate the concordance of surgical step pacing between 2 experienced surgeons following a standardized surgical protocol for bilateral laser in situ keratomileusis (LASIK). SETTING: London Vision Clinic, London, United Kingdom. DESIGN: Retrospective comparative case series. METHOD: This was a video review comprising an equal number of consecutive bilateral LASIK patients for 2 surgeons following a standardized surgical protocol using the Visumax femtosecond laser and MEL 80 excimer laser. Timestamps were recorded for flap creation, flap lift, excimer laser ablation, and flap replacement. Total surgery time was defined with the endpoints of speculum insertion and removal. RESULTS: Each surgeon performed bilateral LASIK on 30 patients. The mean total surgery time was 11 minutes 17 seconds ± 1 minute 46 seconds (SD) for surgeon 1 and 12 minutes 13 seconds ± 1 minute 37 seconds for surgeon 2. The mean bilateral flap creation time was 3 minutes 5 seconds ± 24 seconds and 3 minutes 42 seconds ± 25 seconds, respectively. The mean suction time for an individual eye was 26 seconds ± 4 seconds for surgeon 1 and 23 seconds ± 1 second for surgeon 2. The difference in timing was accounted for by differences in the length of surgeon conversation with patients rather than by physical surgical steps. CONCLUSIONS: Bilateral LASIK procedure time was highly concordant within and between surgeons using a standardized surgical protocol. Use of a standardized surgical protocol can optimize the efficiency of corneal suction time as well as total surgical time while providing the expected equivalency in visual outcomes between surgeons.

Improving the ablation efficiency of excimer laser systems with higher repetition rates through enhanced debris removal and optimized spot pattern.

PURPOSE: To evaluate the reasons for the required increased radiant exposure for higher-repetition-rate excimer lasers and determine experimentally possible compensations to achieve equivalent ablation profiles maintaining the same single-pulse energies and radiant exposures for laser repetition rates ranging from 430 to 1000 Hz. SETTING: Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany. DESIGN: Experimental study. METHODS: Poly(methyl methacrylate) (PMMA) plates were photoablated. The pulse laser energy was maintained during all experiments; the effects of the flow of the debris removal, the shot pattern for the correction, and precooling the PMMA plates were evaluated in terms of achieved ablation versus repetition rate. RESULTS: The mean ablation performance ranged from 88% to 100%; the variability between the profile measurements ranged from 1.4% to 6.2%. Increasing the laser repetition rate from 430 Hz to 1000 Hz reduced the mean ablation performance from 98% to 91% and worsened the variability from 1.9% to 4.3%. Increasing the flow of the debris removal, precooling the PMMA plates to -18°C, and adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the variability. Only adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the mean ablation performance. CONCLUSIONS: The ablation performance of higher-repetition-rate excimer lasers on PMMA improved with improvements in the debris removal systems and shot pattern. More powerful debris removal systems and smart shot patterns in terms of thermal response improved the performance of these excimer lasers.

Comparative study of stromal bed of LASIK flaps created with femtosecond lasers (IntraLase FS150, WaveLight FS200) and mechanical microkeratome.

BACKGROUND/AIM: To compare stromal bed smoothness in LASIK flaps created with two different femtosecond lasers (IntraLase FS150 and WaveLight FS200) and a mechanical microkeratome (MMK) (Carriazo-Pendular microkeratome). METHODS: Sixty freshly enucleated porcine eyes were used for the study. Twenty flaps were created and constitute each of the following three groups: IntraLase FS150 (IFS group), WaveLight FS200 (WFS group) and MMK (MMK group). In each of the three groups, 10 flaps were created with intended thickness of 110 µm and another 10 flaps with 130 µm. Images were assessed with light microscopy and scanning electron microscopy. Qualitative surface roughness grading of the images was performed by five masked observers and statistical comparisons of scores were made between groups. RESULTS: The results of qualitative surface roughness grading demonstrated that there was no significant difference between the two femtosecond (FS) lasers when comparing the subgroups with the same flap thickness (p>0.05 in both comparisons, Mann-Whitney U test). In addition, there was no statistically significant difference (p>0.05) in each flap maker group between different thickness subgroups. However, the scores of the FS laser subgroups were significantly better than the scores of the MMK subgroups with corresponding flap thicknesses (p<0.05, Mann-Whitney U test). CONCLUSIONS: Our study demonstrates that the IntraLase FS150 and the WaveLight FS200 had a similar performance and provided flaps with smooth surfaces. In comparison to the MMK, the studied femtosecond laser systems had a superior performance in terms of smoothness.

[Corneal flap analysis after LASIK and femto-LASIK using optical coherence tomography and optical sections].

Two groups of patients were enrolled into the study, each group included 15 patients (30 eyes). Evolution 3E mechanical microkeratome ("Moria") was used to create LASIK flaps in the 1st group. VISUMAX laser microkeratome ("Carl Zeiss Meditec") was used in the 2nd group. Optical coherence tomography showed irregularity of flap thickness in the 1st group. In the 2nd group flap thickness was regular. According to Pentacam data the posterior corneal surface had no postoperative changes in both groups.

Initial surface temperature of PMMA plates used for daily laser calibration affects the predictability of corneal refractive surgery.

PURPOSE: To investigate the relevance of initial temperature of the polymethylmethacrylate (PMMA) plates used as a target for photoablation during calibration of excimer lasers performed in daily clinical routine. METHODS: An experimental argon fluoride excimer laser with a repetition rate of 1050 Hz, a radiant exposure of 500 mJ/cm², and single pulse energy of 2.1 mJ was used for photoablation of PMMA plates. The initial plate temperature varied from 10.1°C to 75.7°C. The initial temperature was measured with an infrared camera and the central ablation depth of a myopic ablation of -9.00 diopters (D) with an optical zone of 6.5 mm was measured by means of a surface profiling system. RESULTS: The ablation depth increased linearly from 73.9 to 96.3 µm within a temperature increase from 10.1°C to 75.7°C (increase rate of 0.3192 µm/K). The linear correlation was found to be significant (P<.05) with a coefficient of determination of R²=0.95. Based on these results and assuming a standard room temperature of 20°C, optimal plate temperature was calculated to be 15°C to 25°C to maintain an ablation within 0.25 D. CONCLUSIONS: The temperature of PMMA plates for clinical laser calibration should be controlled ideally within a range of approximately ±5°C, to avoid visually significant refractive error due to calibration error. Further experimental investigations are required to determine the influence of different initial corneal temperatures on the refractive outcome.

A review of protocols for 308 nm excimer laser phototherapy in psoriasis.

BACKGROUND: 308 nm excimer laser phototherapy is efficacious in the treatment of localized psoriasis. Different approaches regarding dose fluency, number of treatments, and maintenance have been utilized, and there is yet to be a consensus on standard protocol. OBJECTIVE: To characterize treatment parameters for 308 nm excimer laser phototherapy. METHODS: We performed a PubMed search for studies describing excimer laser treatment protocol with particular attention to dosage determination, dose adjustment, dose fluency, number of treatments, and maintenance. RESULTS: Seven prospective studies were found describing the excimer efficacy for psoriasis. All studies determined the initial treatment dose using either the minimal erythema dose (MED) or induration. Fluency ranged from 0.5 MED (low) to 16 MED (high); one study demonstrated that medium to high fluencies yielded better improvement in fewer number of treatments. Fluency adjustments during the course of treatment were important to minimize phototherapy-associated side effects. The use of higher fluencies was reported to result in higher occurrences of blistering. One study implemented a maintenance tapering of dose-frequency phase to better manage psoriasis flare-ups. CONCLUSION: The 308 nm excimer laser is an effective therapy for psoriasis regardless of the method used to determine initial dosage, dose fluency, or number of treatments. As its usage as a targeted monotherapy increases, future trials should consider evaluating and modifying these parameters to determine the most optimal management of localized psoriasis. Based on our reviewed studies, there is no consensus for a single excimer laser therapy protocol and as a result, patient preferences should continue to be an important consideration for phototherapy regimen planning.