Patient experience and repeatability of measurements made with the Pentacam HR in patients with keratoconus.

BACKGROUND: To investigate whether the repeatability of measurements with the Pentacam HR in patients with keratoconus is improved by patients gaining more experience of the measurement situation. Such an improvement could enhance the accuracy with which progressive keratoconus can be detected. METHODS: Four replicate measurements were performed on Day 0 and on Day 3. Parameters commonly used in the diagnosis of progressive keratoconus were included in the analysis, namely the flattest central keratometry value (K1), the steepest central keratometry value (K2), the maximum keratometry value (Kmax), and the parameters A, B and C from the Belin ABCD Progression Display. In addition, quality parameters used by the Pentacam HR to assess the quality of the measurements were included, namely the analysed area (front + back), 3D (front + back), XY, Z, and eye movements. RESULTS: Neither the diagnostic parameters nor the quality parameters showed any statistically significant improvement on Day 3 compared to Day 0. The quality parameter "eye movements" deteriorated significantly with increasing Kmax. CONCLUSION: Gaining experience of the measurement situation did not increase the accuracy of the measurements. Further investigations should be performed to determine whether the increasing number of eye movements with increasing disease severity has a negative effect on the repeatability of the measurements.

"Ant-egg" cataract revisited.

PURPOSE: Hereditary congenital cataract varies immensely concerning location and form of the lens opacities. A specific and very rare phenotype is called "ant-egg" cataract first described in 1900. "Ant-eggs" have previously been examined using light microscopy, backscattered electron imaging and X-ray scans and electron microscopy. The purpose of this study was to further characterize "ant-egg" cataract using modern technology and display the history of the "ant-eggs" after cataract extraction. METHODS: "Ant-eggs" were examined using Heidelberg SPECTRALIS Optical Coherence Tomography (OCT)(Heidelberg Engineering, Heidelberg, Germany). Ten "ant-eggs" were extracted; four of these as well as control tissue were analyzed by mass spectrometry (AB Sciex). Proteins were identified and their approximate abundances were determined. Immunohistochemical staining was carried out on the remaining "ant-eggs" for cytokeratin and S100. RESULTS: In anterior OCT-images, the "ant-egg" structures are localized on the iris. Comparative pictures showed that they stayed in the same location for more than 45 years. Mass spectrometry of "ant-eggs" yielded a proteome of 56 different proteins. Eighteen of the 56 "ant-egg" proteins (32 %) were neither present in our controls nor in a known fetal lens proteome. Among these were cytokeratin and Matrix-Gla protein. Immunohistochemical reactions were positive for cytokeratin and S100. CONCLUSIONS: This study demonstrates the previously unknown protein composition of the "ant-egg" structures in "ant-egg" cataract. Eighteen of these proteins are not natively found in the human lens. Moreover, "ant-eggs" do not vary over time, after cataract extraction, regarding size and location.

Comparison of corneal shape changes and aberrations induced By FS-LASIK and SMILE for myopia.

PURPOSE: To compare corneal curvatures, corneal power calculations, and higher-order aberrations (HOAs) of femtosecond laser-assisted LASIK (FS-LASIK) with small incision lenticule extraction (SMILE) following surgery for moderate to high myopia. METHODS: A retrospective study of 736 eyes of 368 patients treated with SMILE and 148 eyes of 74 patients treated with FS-LASIK. Preoperative mean spherical equivalent was -7.3 ± 1.5 diopters in the SMILE group and -7.6 ± 1.3 diopters in the FS-LASIK group. Corneal curvatures, corneal power calculations performed by ray tracing, and HOAs measured with Scheimpflug technology before and 3 months after surgery were analyzed. RESULTS: Corneal curvatures changed significantly in the anterior corneal surface, but not in the posterior corneal surface, in both groups; after SMILE, the sagittal curvature was constant for the central 4-mm diameter, in contrast to FS-LASIK where the curvature showed a gradual steepening with increasing diameter. Corneal power calculations were different across the cornea depending on the measurement diameter between the two groups postoperatively. Measured over a 5-mm zone on the total cornea, FS-LASIK induced 0.11 µm more coma (P < .001) and 0.13 µm higher spherical aberration (P < .001) as compared to SMILE; similar results in other HOAs were seen for the anterior corneal surface. Negligible differences in HOAs were induced on the posterior corneal surface. CONCLUSIONS: SMILE and FS-LASIK produced distinct changes in anterior corneal shape evident in different postoperative corneal curvatures and power measurements between the two groups. Postoperative HOAs were much lower after SMILE as compared to FS-LASIK.

Venting incisions in DSAEK: implications for astigmatism, aberrations, visual acuity, and graft detachment.

PURPOSE: To evaluate the impact of venting incisions on the best corrected visual acuity (BCVA), astigmatism, aberrations, and risk of graft detachment in Descemet stripping automated keratoplasty (DSAEK). METHODS: This was a retrospective, comparative, consecutive case series of DSAEK procedures performed with (n = 266) and without (n = 110) venting incisions. Patients were treated with DSAEK for Fuchs' endothelial dystrophy at Aarhus University Hospital between 2011 and 2013. Data included preoperative keratometry and postoperative BCVA, subjective astigmatism, and Pentacam® HR tomography with corneal front surface (CFS) aberrations at 1 to 2 years of follow-up. Numbers of triple procedures (concurrent cataract surgery) and post-operative graft detachments were also noted. The venting and non-venting groups were compared by the data-means. Unpaired t-tests and Mann-Whitney tests were used for normally and non-normally distributed data, respectively. Differences in graft detachments were analyzed with Fisher's exact and Chi square test. RESULTS: There was no significant difference in any parameter, except the numbers of triple procedures. BCVA (logMAR) was 0.25 ± 0.18 in the venting group and 0.25 ± 0.19 in the non-venting group (p = 0.92), subjective astigmatism was -1.53 ± 0.99 diopters and -1.33 ± 0.78 diopters (p = 0.15), respectively. CFS astigmatism and higher order aberrations were statistically uniform. The relative risk (RR) of graft detachment was also uniform between the venting versus non-venting group (RR 0.72, p = 0.40), and between triple versus non-triple procedures (RR 0.71, p = 0.43). The preoperative corneal curvature had no impact on the risk of graft detachment (p = 0.74). CONCLUSION: Venting incisions in DSAEK do not significantly alter BCVA, astigmatism, CFS aberrations or reduce the risk of graft detachment in triple or non-triple procedures.

Assessing the corneal power change after refractive surgery using Scheimpflug imaging.

PURPOSE: To investigate whether the Pentacam HR could accurately predict the surgically induced refractive change in patients operated with small-incision lenticule extraction (SMILE) for myopia or femto-second laser in situ keratomileusis (FS-LASIK) for myopia or hyperopic astigmatism. METHODS: Data from three groups consisting of (1) 410 myopic eyes of 410 patients operated with SMILE, (2) 111 myopic eyes of 111 patients operated with FS-LASIK, and (3) 40 eyes of 40 patients with hyperopic astigmatism operated with FS-LASIK were retrospectively analysed. The change in manifest refraction due to surgery was compared with the objectively measured change in corneal power by the Pentacam HR in three different ways: Sagittal Power (calculated as for placido topographers), True Net Power (calculated by a Gaussian optics formula), and Total Corneal Refractive Power (calculated by ray tracing). Multiple linear regression analysis was performed to investigate which parameters influenced the Pentacam HR's prediction of the change in subjective refraction due to surgery. RESULTS: The Total Corneal Refractive Power Apex, Zone calculation in a diameter of 4.0 mm effectively predicted the surgically induced refractive change for all three patient groups. The spherical equivalent was predicted with an error of 0.08 ± 0.41 D for the SMILE eyes, 0.05 ± 0.61 D for the myopic eyes operated with FS-LASIK, and -0.15 ± 0.49 D for the hyperopic astigmatic eyes treated with FS-LASIK. Regression showed that preoperative refractive error had a significant impact on the prediction error of the Pentacam HR. CONCLUSIONS: Ray tracing calculations based on Scheimpflug imaging accurately assessed the change in manifest refraction due to corneal laser surgery.

Safety and complications of more than 1500 small-incision lenticule extraction procedures.

PURPOSE: To evaluate the safety and complications of small-incision lenticule extraction (SMILE). DESIGN: Clinical control cohort study. PARTICIPANTS: A total of 922 healthy patients (1800 eyes) who were treated for myopia or myopic astigmatism between January 2011 and March 2013 at the Department of Ophthalmology, Aarhus, Denmark. METHODS: Patients received a full preoperative examination and were treated with SMILE in both eyes and followed for 3 months (1574 eyes). Patients with complications, including loss of corrected distance visual acuity (CDVA) or dissatisfaction, were offered a late reexamination. MAIN OUTCOME MEASURES: Surgical complications and CDVA. RESULTS: Mean preoperative spherical equivalent refraction was -7.25±1.84 diopters (D). Average postoperative refraction was -0.28±0.52 D, and mean error of treatment was -0.15±0.50 D. By 3 months, 86% (1346 eyes) had unchanged or improved CDVA. A loss of 2 or more lines was observed in 1.5% of eyes; however, at a late follow-up visit (average, 18 months), CDVA was within 1 line of the preoperative level in all eyes. Perioperative complications included epithelial abrasions (6%), small tears at the incision (1.8%), and difficult lenticule extraction (1.9%). The cap was perforated in 4 eyes, and a major tear occurred in 1 eye; however, none of these patients had late visual symptoms. In 0.8% (14 eyes), suction was lost during surgery. Re-treatment was successful in 13 eyes, whereas 1 eye had ghost images and was re-treated with topography-guided photorefractive keratectomy (PRK). Postoperative complications included trace haze (8%), epithelial dryness on day 1 (5%), interface inflammation secondary to central abrasion (0.3%), and minor interface infiltrates (0.3%); these complications had an impact on CDVA at 3 months in only 1 case. Irregular corneal topography occurred in 1.0% of eyes, resulting in reduced 3-month CDVA (12 eyes) or ghost images (6 eyes). Topography-guided PRK was performed in 4 eyes, with improvement in 3 cases. Satisfaction was high, with only 2 patients dissatisfied at their latest visit because of blurred vision or residual astigmatism. CONCLUSIONS: Overall, SMILE had acceptable safety. Although 1.5% of eyes had reduced CDVA by 3 months, visual acuity was restored in the long term. Likewise, patient satisfaction was high.

Correction of myopic astigmatism with small incision lenticule extraction.

PURPOSE: To evaluate the outcome after small incision refractive lenticule extraction (SMILE) in patients with myopic astigmatism. METHODS: Seven hundred seventy-five eyes from 403 patients with myopia treated with SMILE for a cylinder of 0.75 diopters (D) or more were identified from patient records. Six hundred sixty-nine eyes were defined as receiving low (< 2.5 D) and 106 eyes as receiving high (⩾ 2.5 D) astigmatic correction. Patients were examined before and 3 months after surgery. SMILE was performed with a Visumax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). Preoperative and postoperative refractions were converted to polar values. Induced torsion and achieved corrections of sphere and cylinder were determined. RESULTS: In low astigmatism, the mean preoperative spherical equivalent (SE) was -7.57 ±1.67 D and the cylinder was -1.22 ± 0.49 D. Three months after surgery, SE was -0.19 ± 0.48 D from target, astigmatism was 0.17 ± 0.42 D undercorrected, and a small but significant torsion of the cylinder axis corresponding to 0.05 ± 0.37 D was found. The astigmatic undercorrection measured 13% per diopter of attempted correction. In high astigmatism, preoperative SE was -5.91 ± 2.56 D and cylinder was -3.22 ± 0.67 D. After surgery, the average astigmatic undercorrection was 0.59 ± 0.65 D, equivalent to 16% per diopter of attempted correction. No undercorrection in SE occurred and no torsion was found. CONCLUSIONS: SMILE in myopic astigmatism offers predictable correction of SE, but a small, significant undercorrection of the astigmatic error. The undercorrection increases with the attempted treatment. Only very little rotation of the cylinder axis was found.

Topography-guided photorefractive keratectomy for irregular astigmatism after small incision lenticule extraction.

PURPOSE: To report the outcome of topography-guided photorefractive keratectomy (PRK) after complicated small incision lenticule extraction (SMILE). METHODS: Retrospective case series of 5 eyes with irregular topography and ghost images after complicated SMILE. All eyes received transepithelial topography-guided PRK. Two eyes were treated with 0.02% mitomycin C. Patients were examined after a minimum of 3 months with evaluation of uncorrected (UDVA) and corrected (CDVA) distance visual acuity, Pentacam tomography (Oculus Optikgeräte, Wetzlar, Germany), and whole-eye aberrometry. RESULTS: In 3 eyes, subjective symptoms were diminished and UDVA, CDVA, topography, and corneal wavefront aberrations were improved. The remaining 2 eyes developed significant haze with worsened topography and wavefront aberrations. One eye experienced a two-line reduction in CDVA. Eyes with haze development had not been treated with mitomycin C. CONCLUSIONS: Transepithelial topography-guided PRK may reduce visual symptoms after complicated SMILE if postoperative haze can be controlled. To reduce the risk of haze development, application of mitomycin C may be considered.

Dynamic Scheimpflug-based assessment of keratoconus and the effects of corneal cross-linking.

PURPOSE: To evaluate the ability of the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) to distinguish between normal and keratoconic corneas and detect the possible stiffening effect of corneal cross-linking (CXL) in vivo. METHOD: A retrospective study including 86 eyes of 86 participants (27 patients with untreated keratoconus, 27 patients with CXL-treated keratoconus, and 32 normal patients). The prospective study included 9 keratoconic eyes measured 24 days before and 97 days after CXL. RESULTS: The following parameters from the Corvis ST showed a significant difference between keratoconic and normal eyes: intraocular pressure, corneal thickness, first applanation time, highest concavity (HC) radius, HC deformation amplitude, and HC deflection amplitude (analysis of variance, P < .0001). Receiver operating characteristic curve analysis showed the highest area under the curve for HC deflection amplitude (0.942, P < .0001). Prediction intervals for individual measurements within the two groups overlapped considerably. No significant difference was found between the untreated and CXL-treated keratoconus groups (analysis of variance, P > .05). Measurements performed before and after CXL in the same patients showed significant difference in HC deformation amplitude (P = .018), HC time (P = .018), and second applanation time (P = .027). CONCLUSIONS: Although the corneal deformation characteristics differed between groups of keratoconic and normal eyes, this study showed that the standard parameters of the Corvis ST cannot readily be used for diagnosis of keratoconus in the individual patient or to document the effect of CXL in vivo.

Central corneal sublayer pachymetry and biomechanical properties after refractive femtosecond lenticule extraction.

PURPOSE: To compare central corneal sublayer pachymetry and biomechanical properties after femtosecond lenticule extraction (FLEX) and small-incision lenticule extraction (SMILE). METHODS: A prospective, randomized, single-masked clinical trial of 35 patients treated for moderate to high myopia with FLEX in one eye and SMILE in the other. Anterior segment optical coherence tomography imaging (Heidelberg Spectralis; Heidelberg Engineering GmbH, Heidelberg, Germany) was used to measure central corneal thickness (CCT) and epithelial, flap/cap, and residual stromal bed thickness centrally. The Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY) was used to assess corneal hysteresis (CH) and corneal resistance factor (CRF). Patients were examined before and 6 months after surgery. RESULTS: Mean decrease in CCT was 105 µm in FLEX-treated eyes and 106 µm in SMILE-treated eyes (P = .70), which is equivalent to approximately 14 µm/diopters corrected. Mean central epithelial thickness increased 7 ± 6 µm in FLEX-treated eyes and 6 ± 5 µm in SMILE-treated eyes (P = .64). Achieved mean flap/cap thickness was 4 ± 6 µm from the expected thickness in FLEX-treated eyes and 4 ± 9 µm in SMILE-treated eyes (P = .37). CH was reduced 2.7 ± 1.3 mm Hg in FLEX-treated eyes and 3.3 ± 1.2 mm Hg in SMILE-treated eyes (P = .08). CRF was reduced 4.5 ± 1.2 mm Hg in FLEX-treated eyes and 4.6 ± 1.2 mm Hg in SMILE-treated eyes (P = .71). CH and CRF were highly correlated with CCT, but not patient age. CONCLUSIONS: In this paired-eye study, the flap-based FLEX and cap-based SMILE resulted in almost identical changes in central corneal sublayer pachymetry and biomechanical properties for moderate to high myopia 6 months after treatment.

Corneal biomechanical properties after LASIK, ReLEx flex, and ReLEx smile by Scheimpflug-based dynamic tonometry.

PURPOSE: To evaluate corneal biomechanical properties after LASIK, ReLEx flex, and the flap-free procedure ReLEx smile by Scheimpflug-based dynamic tonometry (Corvis ST) and non-contact differential tonometry (Ocular Response Analyzer, ORA). METHODS: Patients treated for high myopia (-10.5 to -5.5 diopters, spherical equivalent refraction) more than one year previously at Aarhus University Hospital were included. Treatments comprised LASIK (35 eyes), ReLEx flex (31 eyes), and ReLEx smile (29 eyes). A control group included 31 healthy eyes. Cornea-compensated IOP (IOPcc), corneal hysteresis (CH), and corneal resistance factor (CRF) were measured with ORA. Corneal applanation and deformation were registered with Corvis ST during an air-pulse. RESULTS: Multiple linear regression analysis showed that CH and CRF were significantly lower after all keratorefractive procedures compared to healthy controls (p < 0.05). No significant differences were observed in CH or CRF between the keratorefractive groups. Corvis ST showed no differences in radius at highest concavity (HC radius), time until first applanation (A1 Time), time until second applanation (A2 Time), and deflection length at highest concavity (HC deflection length) between groups. LASIK treated eyes had significantly shorter time until highest concavity than eyes treated with ReLEx smile (HC Time, p = 0.01). The A1 deflection length was significantly shorter in the keratorefractive groups compared to the healthy controls (p < 0.05). CONCLUSIONS: Keratorefrative procedures alter the corneal biomechanical properties with regard to corneal hysteresis and corneal resistant factor. The flap-based LASIK and ReLEx flex and the flap-free ReLEx smile result in similar reduction in corneal biomechanics when evaluated by Corvis ST and ORA.

Comparison of organ cultured precut corneas versus surgeon-cut corneas for Descemet's stripping automated endothelial keratoplasty.

To compare precut and surgeon-cut organ cultured donor corneas for DSAEK. A total of 119 consecutive eyes treated with DSAEK were retrospectically identified. 65 grafts were cut by the surgeon (Moria, ALTK System) prior to DSAEK and 54 grafts were precut by laboratory technicians from the Danish Eye Bank (Horizon single-use system). 1 year after surgery, tomographic images were obtained with the Pentacam HR. Endothelial cell density (ECD) and best-corrected visual acuity (BCVA) was determined. Graft thickness and graft asymmetry was evaluated in the centre and 1 mm from the edge of the graft in 6 semi-meridians. 1 year after surgery, the ECD loss was similar in the two groups, averaging 25.9 ± 14 % in surgeon-cut, and 22.9 ± 17 % in precut group (p = 0.33). Mean central graft thickness was 172 ± 6 µm in surgeon-cut grafts and 182 ± 6 µm in precut grafts (p = 0.30). BCVA was similar in surgeon-cut and precut corneas; being 0.25 ± 0.02 logMAR and 0.24 ± 0.02 logMAR, respectively (p = 0.59). The graft asymmetry index was 1.48 ± 0.02 for surgeon-cut and 1.44 ± 0.02 for precut grafts. There were no significant differences in complications rate in both groups. No correlations between BCVA and central graft thickness or graft asymmetry index in both groups were observed. Organ cultured precut donor corneas are comparable with surgeon-cut grafts with respect to ECD, graft thickness and asymmetry, and postoperative complication rate.

Intraocular pressure-related side-effects after endothelial keratoplasty.

PURPOSE: To investigate circumpapillary retinal nerve fibre layer (RNFL) thickness, pupillary function and diameter after phacoemulsification and lens implantation alone or combined with endothelial keratoplasty (EK). METHODS: This study was a secondary analysis of data from a randomized, single-masked trial, that included 72 patients with Fuchs' endothelial dystrophy and cataract, equally allocated (1:1) to ultrathin Descemet's stripping automated endothelial keratoplasty or Descemet's membrane endothelial keratoplasty. The cataract extraction (CE) group included 40 patients undergoing cataract surgery only. All patients were treated with phacoemulsification and lens implantation. RESULTS: RNFL thickness was significantly lower in the CE group than after EK for the global (p < 0.01), nasal (p = 0.04), and temporal sectors (p = 0.01) 12 months after surgery. RNFL thickness was comparable between patients treated with rebubbling and others (p ≥ 0.16 for all comparisons) after 12 months. The CE group and patients treated with EK demonstrated a comparable scotopic (p = 0.34) and photopic pupil diameter (p = 0.95) as well as a comparable maximum (p = 0.83) and average pupillary constriction velocity (p = 0.95) after 12 months. In contrast, patients treated with rebubbling had a significantly smaller scotopic pupil diameter (p = 0.04). CONCLUSION: In this study, no evidence was found indicating a negative impact on the RNFL thickness after EK when compared to CE 12 months after surgery. Iris function and pupil diameter were comparable between the CE group and patients treated with EK after 12 months.

Long-term outcomes of photorefractive keratectomy for low to high myopia: 13 to 19 years of follow-up.

PURPOSE: To evaluate long-term outcomes after photorefractive keratectomy (PRK). METHODS: A retrospective follow-up study of patients who received PRK at 5.0- to 6.5-mm optical zones, using the Summit broad beam excimer laser (Summit Technology, Inc., Waltham, MA) at Odense University Hospital, Odense, Denmark, between 1992 and 1998. One randomly selected eye of each patient was used in the statistical analyses. Re-treated eyes were excluded. RESULTS: One hundred sixty eyes were included. Mean follow-up time was 16 years (range: 13 to 19 years). Mean preoperative spherical equivalent was -4.84 ± 2.95 diopters (D) (range: -20.25 to -1.25 D). At last follow-up examination, achieved refraction was -1.00 ± 1.56 D (range: -10.75 to +1.00 D) from attempted refraction, and the change in mean refractive error from 6 months postoperatively was less than 1.00 D. Results from a subgroup of unilateral treated patients indicated that myopic progression was the main reason for the residual refractive error. For eyes with low myopia (n = 124), the proportion of eyes within ± 1.0 D of attempted refraction was 72%, and for eyes with high myopia (-6.00 D or more, n = 36) it was 47%. Forty-five percent had uncorrected distance visual acuity of 20/20 or better at last follow-up examination. Three eyes (2%) lost two or more lines and 13 eyes (8%) gained two or more lines of corrected distance visual acuity. Fourteen percent had haze (grade 0.5 to 2). Eighty-one percent were satisfied with the surgery. CONCLUSION: PRK for low degrees of myopia seemed safe and effective up to 19 years after surgery with conventional broad beam laser ablation. Refractive predictability was significantly lower and the occurrence of haze was higher in eyes with high myopia.

Subbasal nerve morphology, corneal sensation, and tear film evaluation after refractive femtosecond laser lenticule extraction.

BACKGROUND: The purpose of this study was to compare corneal subbasal nerve morphology, corneal sensation, and tear film parameters after femtosecond lenticule extraction (FLEX) and small-incision lenticule extraction (SMILE). METHODS: A prospective, randomized, single-masked, paired-eye design clinical trial of 35 patients treated for moderate to high myopia with FLEX in one eye and SMILE in the other. In both techniques, an intrastromal lenticule was cut by a femtosecond laser and manually extracted. In FLEX, a LASIK-like flap allowed removal of the lenticule, whereas in SMILE, it was removed through a small incision. In-vivo confocal microscopy was used to acquire images of the central corneal subbasal nerve plexus, from which nerve density, total nerve number, and nerve tortuosity were analyzed. Corneal sensation was measured using Cochet-Bonnet esthesiometry. A visual analog scale, tear osmolarity, non-invasive tear film break-up time (keratograph) tear meniscus height (anterior segment OCT), Schirmer's test, and fluorescein tear film break-up time were used to evaluate tear film and ocular surface symptoms. Patients were examined before and 6 months after surgery. RESULTS: There were no statistically significant differences in baseline parameters between FLEX and SMILE (p > 0.050). With regard to changes from before to 6 months after surgery, mean reduction in subbasal nerve density was 14.22 ± 6.24 mm/mm(2) in FLEX eyes, and 9.21 ± 7.80 mm/mm(2) in SMILE eyes (p < 0.05). The total number of nerves decreased more in FLEX eyes than in SMILE eyes (p < 0.05). No change was found when comparing tortuosity (p > 0.05). Corneal sensation was reduced with 0.38 ± 0.49 cm in FLEX eyes, and 0.10 ± 0.34 cm in SMILE eyes (p < 0.01). No differences were found between FLEX and SMILE in tear film evaluation tests (p > 0.05). Significantly more patients felt postoperative foreign body sensation in the FLEX eye within the first days after surgery, as compared to the SMILE eye. CONCLUSIONS: Six months after surgery, the less invasive SMILE technique seemed better at sparing the central corneal nerves as compared to FLEX. Corneal sensation was only significantly reduced in FLEX eyes. There were no differences between FLEX and SMILE when comparing tear film evaluation tests 6 months after surgery.

Early findings in a prospective randomised study on three cross-linking treatment protocols: interruption of the iontophoresis treatment protocol.

PURPOSE: To present the outcome of the interrupted iontophoresis-assisted treatment arm in an ongoing randomised clinical trial (NCT04427956). METHODS: A randomised clinical study of corneal cross-linking (CXL) using continuous UV-A irradiation at a rate of 9 mW/cm2 and three different types of riboflavin and riboflavin delivery mode: (1) iso-osmolar dextran-based riboflavin (epithelium-off), (2) hypo-osmolar dextran-free riboflavin (epithelium-off) and (3) iontophoresis-assisted delivery of riboflavin (epithelium-on) for the treatment of progressive keratoconus. Inclusion criteria were an increase in the maximum keratometry value (Kmax) of 1.0 dioptre over 12 months or 0.5 dioptre over 6 months. The primary outcome in evaluating treatment efficacy was Kmax. Recently presented stratified detection limits were used post hoc to confirm the enrolment of patients with truly progressive keratoconus and in the assessment of the need for re-CXL. RESULTS: Thirteen patients had been randomised to iontophoresis-assisted CXL when the treatment arm was interrupted; two patients dropped out. Of the remaining 11 patients, 7 were deemed as having truly progressive disease according to the more recent stratified detection limits. The disease continued to progress in three patients according to the original definition (increase in Kmax≥1 D), necessitating re-CXL with epithelium-off CXL. This progression was confirmed by post hoc analysis using the stratified detection limits for progression. CONCLUSIONS: The iontophoresis-assisted CXL protocol failed to halt further disease progression in 27% of the patients. The failure rate increased to 38% when considering only the patients deemed to have truly progressive disease using the stratified detection limits.

Macular Thickness After Ultrathin Descemet Stripping Automated Endothelial Keratoplasty and Descemet Membrane Endothelial Keratoplasty Combined With Cataract Surgery: A Randomized Controlled Clinical Trial.

PURPOSE: The aim was to investigate alterations in central retinal thickness (CRT) and their implications for visual acuity after ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) combined with cataract surgery. METHODS: A total of 72 eyes of 72 patients with Fuchs endothelial dystrophy and cataract were included and equally randomized to either UT-DSAEK or DMEK. A control group of 40 eyes of 40 patients with cataract were included for cataract surgery. All participants were examined preoperatively as well as 3 and 6 months postoperatively. RESULTS: There was no significant difference in CRT between the study groups after surgery ( P = 0.896). A significant difference in best-corrected visual acuity (BCVA) progression over time was found between the study groups ( P < 0.0001). Average improvements of 8.03 EDTRS after UT-DSAEK ( P < 0.001) and 16.77 EDTRS after DMEK ( P < 0.001) were found 6 months postoperatively. No significant correlation was found between the change in BCVA and CRT from baseline to 3 months postoperatively (r 2 < 0.0001, P = 0.96) and from baseline to 6 months postoperatively (r 2 = 0.0053, P = 0.46). CONCLUSIONS: CRT was not altered by UT-DSAEK, DMEK, or cataract surgery 3 and 6 months postoperatively. BCVA significantly improved 3 and 6 months after UT-DSAEK and DMEK, respectively. No significant correlations were found between the change in BCVA and CRT postoperatively. As such CRT alterations were comparable after UT-DSAEK, DMEK, and cataract surgery.

Visual function after ultrathin Descemet's stripping automated endothelial keratoplasty or Descemet's membrane endothelial keratoplasty combined with cataract surgery: a randomised controlled clinical trial.

AIMS: To compare best-corrected visual acuity (BCVA), contrast sensitivity and endothelial cell density (ECD) after ultrathin Descemet's stripping automated endothelial keratoplasty (UT-DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK). METHODS: A randomised, single-blinded, single-centre design was used. 72 patients with Fuchs' endothelial dystrophy and cataract were randomised to UT-DSAEK or DMEK combined with phacoemulsification and lens implantation. 27 patients with cataract were included in a control group and treated with phacoemulsification and lens implantation. The primary outcome was BCVA at 12 months. RESULTS: Compared with UT-DSAEK, DMEK resulted in better BCVA with mean differences of 6.1 early treatment diabetic retinopathy study (ETDRS) (p=0.001) after 3 months, 7.4 ETDRS (p<0.001) after 6 months and 5.7 ETDRS (p<0.001) after 12 months. The control group obtained significantly better BCVA with a mean difference of 5.2 ETDRS (p<0.001) compared with DMEK 12 months postoperatively. Compared with UT-DSAEK, contrast sensitivity was significantly better 3 months after DMEK with a mean difference of 0.10 LogCS (p=0.03). However, our study found no effect after 12 months (p=0.08). ECD was significantly lower after UT-DSAEK compared with DMEK with mean differences of 332 cells/mm2 (p<0.01) after 3 months, 296 cells/mm2 (p<0.01) after 6 months and 227 cells/mm2 (p=0.03) after 12 months. CONCLUSIONS: Compared with UT-DSAEK, DMEK resulted in better BCVA 3, 6 and 12 months postoperatively. Twelve months postoperatively, DMEK had a higher ECD than UT-DSAEK; however, no difference in contrast sensitivity was found. TRIAL REGISTRATION NUMBER: NCT04417959.

The intra- and inter-day repeatability of corneal densitometry measurements in subjects with keratoconus and in healthy controls.

The healthy cornea is transparent, however, disease can affect its structure, rendering it more or less opaque. The ability to assess the clarity of the cornea objectively could thus be of considerable interest for keratoconus patients. It has previously been suggested that densitometry can be used to diagnose early keratoconus, and that the values of densitometry variables increase with increasing disease severity, indicating that densitometry could also be used to assess progressive keratoconus. Previous studies have only assessed the repeatability of corneal densitometry measurements on the same day, which does not reflect the clinical setting in which changes are evaluated over time. We have therefore evaluated the inter-day repeatability of densitometry measurements in both patients with keratoconus and healthy controls. Measurements in the middle layer of the 2-6 mm zone of the cornea showed the best repeatability. Although an objective measure of the corneal transparency could be interesting, the generally poor repeatability of densitometry measurements limits their use. The repeatability of corneal clarity measurements could be improved by using other approaches such as optical coherence tomography, but this remains to be investigated. Such improvements would allow the more widespread use of corneal densitometry in clinical practice.

Corneal grafting.

Corneal grafting is performed approximately 650 times a year in Denmark. A summary of these procedures is given in this review. Fuchs' endothelial dystrophy and pseudophakic bullous keratopathy are frequent indications for transplantation. Previously, penetrating keratoplasty was the technique of choice but is nowadays mainly used for combined stromal and endothelial pathology. Instead, techniques specifically replacing diseased layers are more common. The Danish Cornea Bank is the only center in Denmark which undertakes preparation and distribution of tissue. The operative procedures are performed at Aarhus University Hospital or Rigshospitalet Glostrup.