Vasyl Druchkiv

Efficacy and predictability of laser in situ keratomileusis for low astigmatism of 0.75 diopter or less

Purpose To examine the refractive and visual outcomes of wavefront‐optimized laser in situ keratomileusis (LASIK) in myopic eyes with low astigmatism of 0.75 diopter (D) or less. Setting University Medical Center Hamburg‐Eppendorf, Germany, and Care Vision private clinics, Germany and Austria. Design Retrospective cross‐sectional data analysis. Methods This study comprised consecutive myopic patients with a preoperative refractive cylinder of 0.75 D or less and a preoperative subjective sphere between −2.75 D and −11.50 D. Three subgroups were formed based on preoperative refractive cylinder magnitude (0.25 D, 0.50 D, and 0.75 D). Manifest refraction, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity were assessed preoperatively and postoperatively. The astigmatic changes were determined using Alpins vector analysis. Results This study enrolled 448 eyes of 448 patients (145 men, 303 women; mean age at surgery 37.8 years ± 9.4 [SD]). By 4 months (mean 116.8 ± 27.7 days) postoperatively, the mean UDVA was 0.10 ± 0.13 logMAR and the mean manifest refraction spherical equivalent (MRSE) −0.05 ± 0.68 D. There was no statistically significant difference in efficacy or safety between the preoperative cylinder groups. Astigmatic overcorrection for a preoperative cylinder of 0.25 D and 0.50 D was suggested by the correction index, the magnitude of error, the index of success, and the flattening index. Conclusions Although the mean UDVA and mean MRSE obtained by the 4‐month follow‐up were appropriate, a preoperative cylinder of 0.50 D or less was significantly overcorrected. Accordingly, caution should be used when considering full astigmatic correction for manifest cylinder of 0.50 D or less. Financial Disclosure Mr. Frings was supported by a grant from Wavelight GmbH, Erlangen, Germany. No author has a financial or proprietary interest in any material or method mentioned.

effects of laser in situ keratomileusis (lasiK) on corneal biomechanical measurements with the Corvis sT tonometer

Purpose This study was initiated to evaluate biomechanical changes using the Corvis ST tonometer (CST) on the cornea after laser in situ keratomileusis (LASIK). Setting University Medical Center Hamburg-Eppendorf, Germany, and Care Vision Refractive Centers, Germany. Design Retrospective cohort study. Methods This retrospective study included 37 eyes of 37 refractive patients. All CST measurements were performed 1 day before surgery and at the 1-month follow-up examination. The LASIK procedure included mechanical flap preparation using a Moria SBK microkeratome and an Allegretto excimer laser platform. Results Statistically significant differences were observed for mean first applanation length, mean first and second deflection lengths, mean first and second deflection amplitudes, radius of curvature, and peak distance. Significant positive correlations were found between the change (Δ) of radius of curvature and manifest refraction spherical equivalent (MRSE), ablation depth, and Δintraocular pressure as well as between AD and ΔHC-time. Each diopter of myopic correction in MRSE resulted in an increase in Δradius of curvature of 0.2 mm. Conclusion Several CST parameters were statistically significantly altered by LASIK, thereby indicating that flap creation, ablation, or both, significantly change the ability of the cornea to absorb or dissipate energy.

Correlation of the KISA% index and Scheimpflug tomography in ‘normal’, ‘subclinical’, ‘keratoconus‐suspect’ and ‘clinically manifest’ keratoconus eyes

To analyse tomographic changes in eyes classified as ‘normal’, ‘keratoconus‐suspect’ and ‘clinically manifest keratoconus’ based on the established KISA% definition of Rabinowitz and Rasheed and to develop the category of ‘subclinical keratoconus eyes’ to expand the classification into a ‘subtopographic’ range.

Ocular residual astigmatism: Effects of demographic and ocular parameters in myopic laser in situ keratomileusis

Purpose To analyze the influence of demographic and ocular factors on ocular residual astigmatism (ORA) in myopic laser in situ keratomileusis (LASIK). Setting University Medical Center Hamburg‐Eppendorf, Hamburg, Germany. Design Retrospective cross‐sectional data analysis. Methods Eyes of consecutive myopic patients scheduled for LASIK were studied to evaluate the influence on preexisting ORA of age, sex, ocular dominance, subjective cylinder and topographic astigmatism, subjective sphere, and mesopic pupil size. The ORA was determined using Alpins vector analysis. Two subgroups, defined by the ratio of ORA to preoperative refractive cylinder (R), were formed: ORA:R ≥1.0 and ORA:R <1.0). Results The study comprised 2991 eyes (2991 patients). The mean ORA was 0.75 diopter (D) ± 0.39 (SD) (range 0.00 to 2.00 D); 1372 (46%) eyes had ORA of 1.00 D or more. Ordinary least square estimations and odds ratios showed that subjective sphere, male sex, and dominant eye were negative predictors of the degree of preoperative ORA, while increasing age and larger mesopic pupils did not indicate ORA orientation. With‐the‐rule astigmatism meridian was more likely in eyes with low ORA, while oblique and against‐the‐rule meridians were related to high ORA. Conclusions The preoperative assessment of refractive surgery candidates should consider the interaction between topographic, refractive, and ORA because corneal refractive surgery is more successful in eyes in which the cylinder mainly originates from the anterior cornea. The current data can help identify patients at high risk for having a significant difference between subjective cylinder and topographic astigmatism. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Visual recovery after retinal detachment with macula-off: is surgery within the first 72 h better than after?

Aims To investigate the influence of lag time between the onset of central visual acuity loss and surgical intervention of macula-off retinal detachment. Methods This retrospective case series examined all consecutively treated eyes with primary macula-off retinal detachment at the University Hospital Hamburg (Germany) from February 2010 to February 2015. Records of 1727 patients operated by six surgeons were reviewed. Eighty-nine eyes (5.2%) from 89 patients met the inclusion and exclusion criteria. The main outcome measure studied was final visual acuity as a function of symptom duration of macula-off detachment. Secondary outcome measures studied were influence of age and surgical technique. Symptom duration was defined as the time from the onset of loss of central vision to surgical intervention. Results After 10 days no clinically relevant difference was seen in final visual acuity. Eyes with symptom duration of 3 days or less achieved best final visual acuity (p<0.001). Age and preoperative visual acuity had no influence while vitrectomised eyes had better outcome compared with those with scleral buckling. Conclusions Our study suggests that 1. After 10 days of central visual acuity loss, the final visual outcome is clinically comparable and independent of further delay of surgery up to 30 days. 2. Eyes treated up to 3 days after onset of loss of central vision have better final visual acuity than eyes with longer lag time. However, we did not find statistically significant differences within the first 3 days. 3. Surgery for macula-off retinal detachment may therefore most likely not be postponed without compromising the patients visual prognosis.

LASIK and PRK in hyperopic astigmatic eyes: is early retreatment advisable?

Purpose To analyze the refractive and keratometric stability in hyperopic astigmatic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) during the first 6 months after surgery. Patients and methods This retrospective cross-sectional study included 97 hyperopic eyes; 55 were treated with LASIK and 42 with PRK. Excimer ablation for all eyes was performed using the ALLEGRETTO excimer laser platform using a mitomycin C for PRK and a mechanical microkeratome for LASIK. Keratometric and refractive data were analyzed during three consecutive follow-up intervals (6 weeks, 3 months, and 6 months). The corneal topography was obtained using Scheimpflug topography, and subjective refractions were acquired by expert optometrists according to a standardized protocol. Results After 3 months, mean keratometry and spherical equivalent were stable after LASIK, whereas PRK-treated eyes presented statistically significant (P<0.001) regression of hyperopia. In eleven cases, hyperopic regression of >1 D occurred. The optical zone diameter did not correlate with the development of regression. Conclusion After corneal laser refractive surgery, keratometric changes are followed by refractive changes and they occur up to 6 months after LASIK and for at least 6 months after PRK, and therefore, caution should be applied when retreatment is planned during the 1st year after surgery because hyperopic refractive regression can lead to suboptimal visual outcome. Keratometric and refractive stability is earlier achieved after LASIK, and therefore, retreatment may be independent of late regression.

Corneal Biomechanical Changes after Crosslinking for Progressive Keratoconus with the Corneal Visualization Scheimpflug Technology

Purpose. To evaluate the effect of corneal crosslinking in progressive keratoconus by applying in vivo corneal visualization Scheimpflug technology. Design. Longitudinal retrospective study. Subjects and Controls. Seventeen eyes of patients treated with corneal crosslinking for progressive keratoconus. Methods. Corneal visualization Scheimpflug technology analyses (research software version 6.07r08) of subjects with progressive keratoconus before and 3 months after corneal crosslinking (CXL) were reviewed retrospectively. t-test (for normal distribution) and Wilcoxon matched-pairs test (if not normally distributed) were used to test for statistically significant differences between pre- and post-CXL analyses. Results. We demonstrated statistically significant differences for the intraocular pressure (median: +3 mmHg, P = 0.004), the central corneal pachymetry (pachy; mean: −35 µm, P < 0.001), the timespan between the air impulse release and the first applanation of the cornea (A1time; median: +0.12 ms, P < 0.05), and the timespan between the air impulse release and the second applanation of the cornea (A2time; median: −37 ms, P < 0.05). Conclusions. With the A1time and the A2time, we identified two parameters that demonstrated a statistically significant improvement of the biomechanical properties of the cornea after CXL. Despite the known initial decrease of the pachymetry after CXL, none of the analyzed parameters indicated a progression of the keratoconus.

Eye laterality: a comprehensive analysis in refractive surgery candidates

Purpose:  To explore eye laterality (higher refractive error in one eye) and its association with refractive state, spherical/astigmatic anisometropia, age and sex in refractive surgery candidates.

Accuracy of wavefront aberrometer refraction vs manifest refraction in cataract patients: impact of age, ametropia and visual function

BackgroundTo evaluate accuracy of WASCA wavefront aberrometry (WA) refraction in comparison to manifest refraction (MR) in an older population awaiting cataract surgery.MethodsProspectively, refractive errors of 130 eyes were determined by WA and MR. Mean age was 65.9 (SD 11.81), corrected distance visual acuity (CDVA) averaged 0.20 logMar (SD 0.57), mean manifest sphere was 0.23 dioptres (D, SD 3.39) and manifest astigmatism amounted to −1.25 D (SD 1.21). For further analysis, refractive values were transformed into power vector components: spherical equivalent (SE), Jackson cross cylinder at 0° and 45° (J0 and J45). The ‘limits of agreement’ approach, regression analysis, correlation analysis, and ANOVA were applied and additionally compared to 28 healthy eyes (mean VA −0.1 logMAR) of a group of young subjects (mean age 33.9).ResultsSE measures in myopia correlated highly between WA and MR (r = 0.917, p < .001). In hyperopia this correlation was moderately high (r = 0.800, p < .001). For all subjects, correlations between WA and MR for J0 and J45 were r = 0.742 (p < .001) and r = 0.760 (p < .001) respectively. WA measurements revealed larger agreement ranges with increasing myopia and astigmatism. Controlled for possible confounding variables of age, VA, and refractive state, no statistically significant effects were found. Across nearly all conditions, WA measured significantly higher myopic and astigmatic values than MR. Most effects were replicated in the reference group.ConclusionsWA refraction can provide valuable information in previously under-researched conditions such as reduced VA (cataract-related), advanced age, and hyperopia. However, loss of optical media transparency will inherently reduce accuracy of WA. Further studies are needed to define cut-off values for automated wavefront quality grading and intra-operative application of WA in refractive surgery.

Flap-induced astigmatism in eyes with sphere myopia correction: Superior hinge using a rotating microkeratome versus nasal hinge using a linear microkeratome

Purpose To compare the effect of a rotating microkeratome (M2) and a linear microkeratome (SBK) on the change in the astigmatic component in eyes with preoperative plano refractive cylinder. Setting University Medical Centre Hamburg‐Eppendorf, Hamburg, Germany. Design Retrospective case series. Methods An Allegretto excimer laser was used to perform laser ablation in myopic eyes of consecutive patients. The laser in situ keratomileusis (LASIK) procedure included mechanical flap preparation using a microkeratome, either a linear type with a single‐use 90 &mgr;m head to create a nasal hinge or a rotating type with a single‐use 90 &mgr;m head to create a superior hinge. The Alpins vector method was applied to describe the effects of LASIK on postoperative refractive cylinder. Results The study evaluated 1045 eyes of 852 patients. Although the mean overall efficacy and safety indices indicate the procedure was highly precise, safe, and efficient, there were statistically significant differences in surgically induced astigmatism (SIA) between the microkeratomes (P = .002). The postoperative refractive cylinder (ie, SIA) was 0.75 diopter (D) or more in 116 eyes (11.1%), 44 (12.8%) of 344 linear cases and 72 (10.3%) of 701 rotating cases. Independent of the type of microkeratome used, the SIA was slightly higher in eyes treated first; the mean magnitude of the induced astigmatism was 0.35 D. Conclusions In approximately 10% of eyes with preoperative plano refractive myopia, the astigmatic component tended to be overcorrected. Nevertheless, independent of the type of microkeratome, the maximum mean magnitude of refractive cylinder documented was 0.35 D. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.