Mean Keratometry Research Articles

Repeatability and comparison of Corvis ST parameters before and after accelerated transepithelial corneal cross-linking in keratoconus eyes

AIM: To evaluate the repeatability and comparison of corneal visualization scheimpflug technology (Corvis ST) parameters in keratoconus eyes before and after accelerated transepithelial corneal cross-linking (ATE-CXL). METHODS: Thirty eyes of 30 progressive keratoconus patients were included in the prospective study. Three repeated corneal biomechanical measurements were performed preoperatively and one month postoperatively by Corvis ST. The interclass correlation coefficient (ICC) and 95% confidence interval (CI), Cronbach’ α, repeatability coefficient (RC), and coefficient of variation (CV) were used to evaluate the repeatability of Corvis ST parameters. Paired t test or Wilcoxon rank test was used to evaluate the differences between preoperative and postoperative data. RESULTS: At preoperative, 26 of 39 (66.67%) parameters showed good to excellent repeatability, 6 (15.38%) showed moderate, and 7 (17.95%) showed poor repeatability. Similarly, 34 (87.18%) parameters showed good to excellent repeatability, 3 (7.69%) showed moderate, and 2 (5.13%) showed poor repeatability after ATE-CXL. After ATE-CXL 1mo, the intraocular pressure (IOP), biomechanical corrected IOP (bIOP), first applanation time (A1T), Radius, deformation amplitude at the first applanation (A1DA), deflection length at the maximum deformation (HCDLL) and stiffness parameter at first applanation (SP A1) parameters increased, while the steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Kmean), second applanation time (A2T), DA Ratio Max (2 mm) and integrated radius parameters decreased (all P<0.05). CONCLUSION: The repeatability of the Corvis ST parameters before and 1mo ATE-CXL follow up were both acceptable, and the corneal stiffness was improved after 1-month ATE-CXL.

Correction of postkeratoplastic astigmatism by intrastromal corneal segments implantation using a femtosecond laser

Background. After penetrating keratoplasty, mild to high induced corneal astigmatism was observed in each case. The existing choice of correction of postkeratoplastic astigmatism is aimed at fi nding an individual approach in order to compensate for it and not weaken the biomechanical properties of the corneal graft.The aim: to analyze the clinical, functional, and morphological results of postkeratoplastic astigmatism correction by implantation of intrastromal corneal segments using a femtosecond laser.Methods. 22 patients were examined before and 1 year after surgery. The operation was performed under local anesthesia: stage I – an intrastromal tunnel was formed using a femtosecond laser “Femto Visum” 1 MHz (Optosystems, Russia); stage II – the intrastromal corneal segments were implanted. The results were assessed using standard and special research methods using optical coherence tomography Visante OCT (Zeiss, Germany), keratotopography (Tomey-5, Japan), optical corneal analyzer ORA (Reichert, USA), laser tindalemetry FC-2000 (Kowa, Japan) and confocal microscope Confoscan-4 (Nidek, Japan).Results. Before the operation, uncorrected visual acuity averaged 0.09 ± 0.05, after a year – 0.50 ± 0.16; best corrected visual acuity – 0.30 ± 0.12 and 0.60 ± 0.05 respectively; cylindrical component of refraction – –10.29 ± 3.12 and –2.20 ± 0.64 D respectively; mean keratometry value – 43.59 ± 2.14 and 38.56 ± 1.75 D respectively; corneal hysteresis – 7.92 ± 1.22 and 8.95 ± 1.05 mm Hg respectively; corneal resistance factor – 7.01 ± 1.81 and 8.44 ± 1.44 mm Hg respectively; protein fl ux in the moisture of the anterior chamber – 2.97 ± 0.28 and 3.04 ± 0.24 f/ms respectively; endothelial cell density – 1521 ± 327 and 1475 ± 419 cells/mm2 respectively.Conclusion. Intrastromal corneal segments implantation into a corneal graft using a femtosecond laser has efficiency and safety method in correcting postkeratoplastic astigmatism.

Detecting Keratoconus: Feasibility and Findings in Three Pediatric Risk Groups.

To investigate the utility of three corneal screening devices in three groups of children. This was a prospective study of patients with Trisomy 21 (group 1), patients with a first-degree relative with keratoconus (group 2), and control patients (group 3). Informed consent was obtained before testing with the Pentacam (Oculus Optikgeräte GmbH), Orbscan (Orbscan, Inc), and Ocular Response Analyzer (ORA) (Ametek Reichart Technologies). The ability to complete tests, the quality of results, and the corneal parameters obtained for each eye were recorded. A one-way analysis of variance test was used to compare the results between the three groups. Fifty-four patients aged from 7 to 17 years (mean: 11.74 years) were enrolled between July 2014 and July 2016. The number of patients and the percentage of tests completed for groups 1, 2, and 3 were 12 (55%), 21 (87%), and 21 (88%), respectively. The Pentacam values by group were central corneal thickness of 524, 543, and 542 µm (P = .36); thinnest point of 498, 536, and 534 µm (P = .03); corneal front mean keratometry of 44.9, 43.2, and 43.2 (P = .01); and quality score of 1.42, 0.22, and 0.04 (P < .0001), respectively. Orbscan values by group were central corneal thickness of 493, 551, and 550 µm (P = .01) and thinnest point of 451, 536, and 538 µm (P < .0001), respectively. ORA values by group were corneal hysteresis of 10.6, 12.1, and 11.6 (P = .124); corneal resistance factor of 9.9, 11.8, and 11.6 (P = .03); and waveform score of 5.6, 7.6, and 7.3 (P < .0001), respectively. Patients in group 1 completed fewer tests reliably and had thinner corneas and lower corneal resistance factors than patients in groups 2 and 3. Corneal tests used to evaluate adults for keratoconus may not be reliable for the evaluation of certain high-risk pediatric patients. [J Pediatr Ophthalmol Strabismus. 2022;59(2):94-101.].

Photoscreener results with and without cycloplegia and their reliability according to biometric parameters

Our goal in this study is to compare the results of a photoscreener (Plusoptix A12C) with and without cycloplegia and to investigate its reliability as a function of biometric parameters. In total, 250 eyes of 125 children with a mean age of 6.77±1.59years were included in the study. The results of cycloplegic and noncycloplegic Plusoptix A12C measurements and autorefractometer with cycloplegia (CA) were compared. The spherical equivalent (SE) differences between CA and noncycloplegic Plusoptix A12C measurements (NPO) with CA and cycloplegic Plusoptix A12C measurements (CPO) were compared with axial length (AL), anterior chamber depth (ACD), corneal radius of curvature (CR), mean keratometry (meanK) and axial length/corneal radius of curvature ratio (AL/CR) values. The relationships between these were examined. According to amblyopia risk factors (ARFs) based on the criteria in the 2013 AAPOS guidelines, 33 eyes (13%) in the NPO results and 34 eyes (13.6%) in the CPO results were found to be at risk for amblyopia. According to the CA results, the NPO had 67.3% sensitivity and 94.5% specificity, and the CPO 69.4% sensitivity and 89.1% specificity in detecting the values of refractive amblyopia factors determined by the AAPOS. In regard to refraction values determined by the AAPOS for amblyopia, according to CA results, the NPO had 71.4% sensitivity and 88.4% specificity in detecting myopia; 33.3% sensitivity and 93.6% specificity in detecting hyperopia; and 79.4% specificity and 71.2% sensitivity in detecting astigmatism. With regard to refraction values determined by the AAPOS for amblyopia, according to CA results, the CPO had 80.9% sensitivity and 90% specificity in detecting myopia; 13.3% sensitivity and 89.2% specificity in detecting hyperopia; and 44.9% sensitivity and 30.8% specificity in detecting astigmatism. When the SE differences between the CA and NPO values were compared with biometric parameters, a negative correlation was observed with ACD, AL, and especially AL/CR ratio. Both the NPO and CPO showed moderate sensitivity and high specificity in detecting ARFs based on the criteria in the 2013 AAPOS guidelines. Sensitivity for detecting hyperopic risk factors was lower than for myopia and astigmatism. The CPO has no additional clinical advantage. A negative correlation was found between biometric parameters and NPO results. Thus, the NPO is more reliable in myopic children with higher axial lengths, deeper anterior chambers, and increased AL/CR ratios.

Bilateral Differential Topography-A Novel Topographic Algorithm for Keratoconus and Ectatic Disease Screening.

Purpose: The purpose of this study was to establish a novel bilateral differential topographic algorithm and assess its efficacy for screening of keratoconus and corneal ectasia before corneal refractive surgery. Methods: One hundred and sixty-one consecutive patients (115 men and 46 women, aged 22.8 ± 6.8 years) with keratoconus, including clinical keratoconus, subclinical keratoconus, forme fruste keratoconus (FFK), and corneal ectasia (KC group) and one hundred and seventy-four consecutive patients (97 men and 77 women, aged 25.1 ± 6.7 years) with ametropia (control group) visiting the Eye and ENT hospital of Fudan University from June 2018 to April 2021 were included. Bilateral differential keratometry, elevation, and pachymetry topographies were composed based on raw topographic data obtained by a Scheimpflug imaging anterior segment analyzer. Key bilateral differential characteristic parameters were calculated. SPSS 20 (SPSS Inc., IBM) was used for statistical analyses and the receiver operating characteristic (ROC) curves were used to determine the diagnostic efficacies. Results: Mann-Whitney tests detected that the front keratometry, front elevation, corneal pachymetry, and back elevation maximal, mean, and standard deviation values within a 1.5-mm radius of the bilateral differential topography were all significantly higher in the KC group than in the control group (all p-values <0.001). The front keratometry mean (ΔFKmean) and standard deviation (ΔFKsd) and the front elevation standard deviation (ΔFEsd) and maximal (ΔFEmax) values within a 1.5-mm radius of the bilateral differential topography yielded the four highest accuracies (area under the ROC curve = 0.985, 0.985, 0.984, and 0.983, respectively) for discriminating KC cases (including FFK cases) from normal cases. Cut-off values of 0.75 diopters (D) for the ΔFKmean, 0.67 D for the ΔFKsd, 2.9 μm for the ΔFEsd, and 14.6 μm for the ΔFEmax had the highest sensitivities (95.7, 95.0, 96.9, and 95.0%, respectively) and specificities (96.0, 97.7, 94.8, and 95.4%, respectively). Conclusion: Bilateral differential topographic parameters may be efficient for the early detection of keratoconus and corneal ectasia secondary to corneal refractive surgery. This bilateral differential topographic algorithm may complement conventional diagnostic models by improving the sensitivity and specificity of screening for early keratoconus and ectasia before corneal refractive surgeries.

Non-invasive evaluation of meibomian gland morphology and tear film and anterior segment parameters in women with polycystic ovarian syndrome

PurposeTo compare the meibomian glands (MG), non-invasive tear film break-up time (NITBUT), and corneal and anterior segment measurements in patients with polycystic ovary syndrome and healthy women. MethodsThe study included 66 polycystic ovarian syndrome (PCOS) patients and 42 healthy volunteers aged 18–35 years. The first and average NITBUT, MG loss, mean keratometry (Km), central (CCT) and thinnest (TCT) corneal thicknesses, anterior chamber depth (ACD), anterior chamber volume (ACV), irido-corneal angle (ICA), corneal volume (CV) and Ocular Surface Disease Index (OSDI) results were analyzed. ResultsThe mean MG loss values were 29.9 ± 11.9 and 20.8 ± 11.0 in the PCOS and control groups, respectively (p < 0.001). MG loss (meiboscale ≥ 1) was determined in 64 (96.9%) eyes in the PCOS group and in 36 (85.7%) eyes in the control group. There was no significant difference between the groups in respect of NITBUT, OSDI, Km, CCT, TCT, ACD, ACV, ICA and CV values (p > 0.05, for all). ConclusionMG loss is a physiological process which is distinct in PCOS patients, but does not cause tear film alterations. Further studies are needed to show the contributing factors of MGD in PCOS patients.

Compression sutures combined with intracameral air injection versus thermokeratoplasty for acute corneal hydrops: a prospective-randomised trial

AimsTo compare the efficacy of compression sutures combined with intracameral air injection (CSAI) and thermokeratoplasty (TKP) for the management of acute corneal hydrops in keratoconus.MethodsIn this multi-centre randomised clinical trial,...

Refractive Outcomes of Simultaneous Pterygium and Cataract Surgery With Fibrin Glue.

IntroductionPterygium is commonly reported in India because of its tropical location. It is often accompanied by senile cataract. The current study aimed to evaluate the refractive outcomes of patients undergoing simultaneous pterygium and cataract surgery.Materials and methodsA total of 12 patients with cataract and pterygium underwent simultaneous phacoemulsification with a foldable intraocular lens (IOL) followed by pterygium excision with conjunctival limbal autograft secured with fibrin glue under peribulbar anesthesia. Nasal pterygium was present in all the cases, and its size ranged from 2.5 to 3.5 mm from the limbus. All the patients exhibited nuclear sclerotic cataract of grades 2 and 3.ResultsThe results of the patients were analyzed retrospectively. We determined the best-corrected visual acuity ([BCVA] in logMAR), manifest astigmatism, and mean corneal astigmatism before operation and after 12 months of surgery. We also analyzed the correlation between the prediction error (calculated by subtracting the predicted postoperative refraction from the actual postoperative spherical equivalent) and changes in the mean keratometry and prediction errors and pterygium size. The mean age of the patients was 61.9 ± 7.14 years (range: 50-70 years). The mean BCVA at presentation was 0.67 ± 0.24 logMAR units, which significantly increased after surgery to 0.01 ± 0.03 logMAR units (p < 0.001, Wilcoxon signed-rank test). The mean manifest corneal astigmatism significantly reduced from −1.98 ± 0.84 diopters (D) preoperatively to −0.54 ± 0.18 D postoperatively (p < 0.001). Mean corneal keratometry increased from 43.81 ± 1.77 D preoperatively to 44.19 ± 1.76 D postoperatively (p < 0.05). At 12 months, 58.33% and 41.66% of the eyes were within ±0.5 D and ±1.0 D, respectively. A significant correlation was observed between the prediction errors and changes in the mean keratometry (Spearman signed-rank test, r = −0.65, p < 0.05) and pterygium size (Spearman correlation coefficient, r = −0.75, p < 0.05).ConclusionThe simultaneous pterygium and cataract surgery with conjunctival autograft and fibrin glue was safe and effective in providing excellent and predictable refractive outcomes. Steepening of the cornea after combined surgery results in myopia; therefore, the IOL power should be selected appropriately. The use of fibrin glue in surgeries reduces the operative time and postoperative pain and results in early postoperative rehabilitation of patients.

Femtosecond Laser and Mechanical Dissection for ICRS and MyoRing Implantation: A Meta-Analysis.

The aims of this meta-analysis were to evaluate the results of intracorneal ring segments (ICRSs) and MyoRing in the management of corneal ectasia and to compare the clinical outcomes and complication rates between mechanical and femtosecond (FS) laser-assisted surgery. An online electronic search was performed for pre-post studies published until April 2020. Uncorrected distance visual acuity, corrected distance visual acuity, sphere, cylinder, spherical equivalent, steep, flat, and mean keratometry values were considered as outcomes. Weighted mean difference with 95% confidence interval was used as a pooled estimation of intervention efficacy. Of 1484 potentially related studies, 115 studies were finally included in the meta-analysis. Findings of this meta-analysis demonstrated considerable improvement in visual, refractive, and keratometric outcomes in all ICRS models and MyoRing. Intrastromal tunnel creation with both methods yielded similar results. Complication rates were without exception higher when mechanical dissection was used. ICRS and MyoRing are appropriate treatment options for patients with corneal ectasia. Both techniques for tunnel creation are efficacious in achieving good visual, keratometric, and refractive results. Mechanical intrastromal tunnel creation is associated with much higher complication rates when compared with FS laser-assisted technique.

Clinical Outcomes of Accelerated Corneal Cross-Linking for Pediatric Keratoconus.

Aim To assess the efficacy and safety of accelerated corneal cross-linking in the treatment of pediatric keratoconus. Method In this retrospective case series, 29 eyes of 20 pediatric patients with keratoconus underwent accelerated corneal cross-linking. Treatment was delivered at 10 mW/cm2 for 9 minutes with a total dose of 5.4 J/cm2. Clinical evaluation included visual acuities and refractive and Scheimpflug corneal tomography assessments. All patients with a minimum follow-up duration of 24 months were included in the study. Results Mean ± standard deviation age was 15.41 ± 2.13 years (range: 8 to 18 years). Uncorrected distance visual acuity improved significantly from 0.56 ± 0.28 to 0.42 ± 0.29 logMAR (P=0.0003), and corrected distance visual acuity improved significantly from 0.34 ± 0.23 to 0.28 ± 0.22 logMAR (P=0.014). The mean manifest refraction spherical equivalent value was significantly reduced (−0.59 ± 0.95 D, P=0.0024). While mean flat keratometry and steep keratometry values were not significantly altered (P > 0.05 for both), the mean maximum keratometry value was significantly decreased from 56.97 ± 5.24 D preoperatively to 55.84 ± 5.37 D at 24 months postoperatively (P=0.003). Maximum keratometry had progressed by >1 D in two eyes (6.89%). Permanent corneal haze was reported in one case (3.44%). Conclusion Our 24-month follow-up demonstrated that accelerated corneal cross-linking appears to halt the progression of keratoconus in pediatric patients without apparent complications. Uncorrected and corrected distance visual acuities were also improved.

The effect of pterygium surgery on intraocular lens power and ocular biometric parameters.

To evaluate the effect of pterygium surgery on intraocular lens (IOL) power and ocular biometric parameters and to evaluate the factors affecting these parameters. Twenty-eight eyes of 25 patients diagnosed with pterygium were evaluated. Axial length (AL), mean keratometry (Sim K), K1, K2, anterior chamber depth (ACD), corneal astigmatism, and ocular biometry parameters were obtained with a dual Scheimpflug analyzer. Pterygium sizes (horizontal, vertical) were measured manually, and pterygium height was analyzed with anterior segment optic coherence tomography. IOL power was calculated according to SRK/T, SRK II, Hoffer Q, Haigis, and Holladay formulas. Limbal conjunctival autograft was performed in all patients after excisional pterygium surgery. Preoperative and postoperative 1st month measurements were analyzed and compared. The mean age of the patients was 51.5 ± 13.8 years. Mean horizontal pterygium length, vertical width, height, and percentage extension of the pterygium were 2.4 ± 0.9, 4.7 ± 1.0 mm, 297 ± 93µm, and 20.2 ± 7.2%, respectively. There was a significant increase in Sim K, K1, and K2 values postoperatively. Postoperative IOL power was significantly lower than preoperative values in all formulas. The change in IOL power after surgery was -0.3 ± 0.6D in the SRKT, -0.3 ± 0.5D in SRK II, -0.4 ± 0.7D in Hoffer Q, -0.5±0.7D in Haigis, and -0.3 ± 0.7D in Holladay 2 formulas. The change in IOL power has a moderate positive linear correlation with the horizontal and vertical sizes of the pterygium and a high positive linear correlation with the percentage extension of the pterygium. Pterygium surgery causes a significant decrease in calculated IOL power obtained with all formulas. It becomes more pronounced with the increase in the size of the pterygium.

Corneal Cross-Linking for Keratoconus and Post-LASIK Ectasia and Failure Rate: A 3 Years Follow-Up Study.

PurposeTo report the response of keratoconus (KC) and post-LASIK ectasia (referred to as “ectasia”) to the corneal crosslinking (CXL) and to compare the rate of progression between KC and ectasia at three years.MethodsA retrospective cohort study of patients undergoing CXL for either KC or ectasia. Fifty-four eyes (31 patients) with ectasia and 111 eyes (67 patients) with KC were included in the study. Corrected distance visual acuities (CDVA), refraction, keratometry (K), and pachymetry were followed up for three years. Simultaneous photorefractive keratectomy (PRK) and CXL were performed on 20 KC and 20 ectasia eyes. Intrastromal Corneal Ring Segments (ICRS) were performed on 51 KC and six ectasia eyes.ResultsIn KC, CDVA, spherical equivalence, sphere, cylinder, and mean K improved at three years post-CXL (p-value<0.05), but these values improved without reaching a statistical significance in ectasia(p-values <0.05). 12 of 54 eyes with ectasia (22.2%) and 4 of 111 eyes (3.6%) with KC had progression post CXL(p-value:0.0001). Ectasia patients diagnosed with progression were older at presentation (36.1 years) than non-progressive ectasia patients (31 years) (p-value 0.02) and also older than KC patients.Sub-analysis excluding PRK and ICRS cases showed that there was an improvement in mean sphere (from -5.23±4.2D to-4.46±3.89D) (p-value 0.03) cylinder (from 2.54 ± 1.68D to 1.97 ± 1.51D) (p-value 0.03) mean keratometry (from 46.81 ± 3.78D to 46.01 ± 3.25D) (p-value 0.006) in KC patients 3 years post CXL (40 patients). Compared to baseline, all the mean refractive and topographic variables deteriorated at three years post CXL in ectasia (28 patients) (p-value>0.05). Also, 2 of 40 patients with KC (5%) vs. 7 of 28 patients with ectasia (25%) had progression three years post-CXL, and the difference between both groups remained statistically significant(p-value 0.027).ConclusionEyes with post-LASIK ectasia seem to be less responsive to CXL than KC.

Myopia progression and axial elongation in Spanish children: Efficacy of atropine 0.01% eye-drops

To assess myopia progression in Spanish children and whether treatment with low-dose atropine eye drops delays myopia progression and axial elongation. 339 eyes of 339 Caucasian patients with myopia, aged 5 to 11 years, were examined. Participants were randomized to a treatment arm, receiving one atropine (0.01%) eye drop/day for two, and an untreated control arm. At the baseline and 2-year follow-up visits, we recorded: spherical equivalent (SE), axial length (AL), mean keratometry (Mean-K) and anterior chamber depth (ACD). We also examined the rate of children with higher myopia progression (change in SE >1 D/2 years) and identified risk factors for progression. In 339 eyes of the 339 children (age=7.61; SD 1.70; range 5-11 years), the mean baseline SE was-2.15 (SD 0.62) D, and AL was 24.24 (SD 0.79) mm. After 2 years, higher increases occurred in all variables except ACD in the untreated group vs. the atropine group, respectively: SE (-0.51 (SD 0.39) D vs. -0.76 (SD 0.37) D, P<0.001), AL (0.20 (SD 0.20) mm vs. 0.37 (SD 0.27) mm, P<0.001) and Mean-K (0.01 (0.28) D vs. 0.09 (0.32) D, P=0.018). Myopia progression was reduced by 32% in the treatment group. There were more progressors >1D/2y in the control group: 62/168 (36.9%) vs. 35/171 (20.5%) (P<0.001). Atropine was identified as a protective factor against myopia progression (B=1.12; 95% CI= 0.98-1.27; P=<0.001). Spanish children showed a low rate of myopia progression. Atropine 0.01% showed a significant effect in slowing the progression of both refractive error and axial elongation.

A New Pre-descemetic Corneal Ring (Neoring) in Deep Anterior Lamellar Keratoplasty for Moderate-Advanced Keratoconus: A Pilot 2-Year Long-Term Follow-Up Study.

Purpose: To assess the outcomes of implanting a new polymethylmethacrylate (PMMA) ring (Neoring; AJL Ophthalmic) in pre-descemet deep anterior lamellar keratoplasty (PD-DALK) procedure for moderate-advanced keratoconus.Methods: This prospective study included 10 eyes of 10 patients with moderate-advanced keratoconus who underwent PD-DALK with Neoring implantation. Neoring was implanted in a pre-descemetic pocket. The post-operative examination included refraction, corrected distance visual acuity (CDVA), corneal tomography, and endothelial cell density (ECD). The root mean squares (RMSs) for coma-like aberrations and spherical aberration were evaluated for a pupil size of 4.5 mm. The junctional graft (Tg) and host (Th) thicknesses were measured. The post-operative follow-up was 24 months.Results: Post-operative CDVA was 0.82 ± 0.14 (decimal scale), 100% of the eyes achieved a CDVA of 0.7 (decimal scale). The refractive cylinder was −2.86 ± 1.65 2-years after surgery. No eyes had a post-operative refractive cylinder ≥5.00 D and in five eyes (50%), it was ≤2.50 D. At the last visit, the mean keratometry was 45.64 ± 1.96 D, the RMS for coma-like aberrations was 0.30 ± 0.15 μm and spherical aberration was 0.22 ± 0.09. The mean ECD remains without changes over the follow-up (P = 0.07). At the last visit, Tg and Th were 679.9 ± 39.0 and 634.8 ± 41.2 μm, respectively. The thickness of the complex (host-Neoring) was 740.6 ± 35.6 μm. In all cases, this thickness was thicker than Tg.Conclusion: The results of this study suggest that PD-DALK along Neoring implantation is a viable, effective, and safe option to optimize the post-operative results for moderate-severe keratoconus.

Comparative Analysis of Corneal Parameters in Swept-Source Imaging between DMEK and UT-DSAEK Eyes.

Background: The need to provide a comparative analysis of corneal parameter changes compared to their preoperative values between Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) patients. Methods: The study included 24 eyes after UT-DSAEK and 24 eyes after DMEK. Visual acuity, endothelial cell count (ECC), central corneal thickness (CCT), mean keratometry (MK), mean astigmatism (MA), astigmatism asymmetry (AA) and higher-order aberrations (HOAs) were assessed at baseline and 1, 3, 6 and 12 months after the surgery. Results: From the 3rd month post operation, ECC was higher in the DMEK eyes than in the UT-DSAEK eyes (p = 0.01). In a bivariate analysis that was adjusted for age, DMEK was associated with a smaller decrease in posterior MK at the 1-month (β = −0.49, p = 0.002), 3-month (β = −0.50, p < 0.001), 6-month (β = −0.58, p < 0.001) and 12-month (β = −0.49, p < 0.001) follow-up visits. There were no significant differences in changes in anterior or combined surface MK throughout the observation period. Accordingly, no significant differences in changes in MA, AA or HOAs compared to the baseline values were identified between the eyes after DMEK and UT-DSAEK at any follow-up time point. Conclusions: UT-DSAEK seemed to be an easier and safer technique than DMEK while maintaining similar outcomes regarding irregular astigmatism and total keratometry values.

Long-term visual, anterior and posterior corneal changes after crosslinking for progressive keratoconus.

To evaluate the long-term outcomes of corneal cross-linking (CXL) in patients with progressive keratoconus. In this retrospective non-comparative study, forty-five eyes of 31 patients with progressive keratoconus were treated with 30 min "epi-off" corneal cross-linking. The visual, refractive, topographic and tomographic outcomes were evaluated preoperatively and at least 10 years after cross-linking. Ten years post-corneal cross-linking, the mean anterior maximum keratometry decreased (-2.10 ± 3.25 D, P = 0.0001). Conversely, the posterior maximum keratometry increased (6.38 ± 9.79 D, P = 0.065). Both uncorrected and corrected distance visual acuity improved (LogMAR -0.08 ± 0.30) and (LogMAR -0.05 ± 0.21), respectively (P > 0.05, both). A statistically significant hyperopic shift was observed postoperatively (0.70 ± 1.31 D, P = 0.0009). The anterior topographic cylinder values revealed no change (-0.17 ± 1.31 D, P = 0.3), whereas the mean posterior cylinder values decreased (absolute value increased) significantly compared to baseline from -1.31 ± 0.97 D to -1.82 ± 1.78 D, (P < 0.05). The minimum corneal thickness values decreased significantly (-35.11 ± 48.63 µm, P = 0.0001). Four eyes (8.8%) showed more than 1 D increase in the anterior maximum keratometry. This protocol and duration of Epi-off corneal cross-linking was found to be effective in halting keratoconus progression over the follow up period (10 years). Anterior corneal flattening and a hyperopic shift were observed. A statistically significant increase in the posterior corneal cylinder was observed. Although, not reaching statistical significance, the logMAR uncorrected and corrected visual acuity were improved.

Changes in Intraocular Pressure and Factors that Influence such Changes after FS-LASIK and SMILE

Purpose: We compared the intraocular pressure (IOP) changes and the relationships thereof with corneal biomechanics after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK).Methods: A total of 234 eyes of 117 patients who underwent FS-LASIK surgery and 244 eyes of 122 patients who underwent SMILE surgery were included in this retrospective study. Data were collected preoperatively, and at 1, 3, and 6 months postoperatively, including IOP measured via non-contract tonometry, central corneal thickness (CCT), and mean keratometry (Km), flat keratometry (Kf), and steep keratometry (Ks) data obtained using a dual Scheimpflug analyzer. Between-group differences were compared. Simple linear regression analysis was used to determine the relationship between changes in the IOP and the various parameters.Results: The IOP changes were 5.41 ± 2.28 mmHg in the FS-LASIK group and 4.77 ± 2.38 mmHg in the SMILE group, thus significantly different (p = 0.004). The IOP did not change significantly from 1 to 6 months after FS-LASIK but increased significantly from 12.07 ± 1.77 mmHg at 3 months postoperatively to 12.77 ± 1.89 mmHg at 6 months postoperatively after SMILE (p = 0.002). All of the preoperative spherical equivalent and IOP, and changes in the Km, Kf, Ks, and CCT, were significantly associated with the IOP changes in both groups. The preoperative IOP evidenced the strongest relationship with the IOP changes in both groups (R2 = 0.414 in the FS-LASIK group, R2 = 0.292 in the SMILE group).Conclusions: The IOP fell significantly after FS-LASIK and SMILE surgery, significantly more so after FS-LASIK than SMILE. The preoperative IOP exhibited the greatest influence on the IOP decreases after both FS-LASIK and SMILE.

Belin ABCD Progression Display Identifies Keratoconus Progression Earlier Than Conventional Metrics

To compare the progression rate and time to progression determined using the Belin ABCD Progression Display (BAPD) with conventional metrics in patients with keratoconus (KC). Retrospective comparison of progression assessment. Patients 18 years and older and 35 years and younger with at least 1 year of follow-up and 3 Pentacam (Oculus, Inc) visits were included in the study. Progression was evaluated by selecting either the first visit or the first 2 visits individually as the baseline on the BAPD, and the red gate was used to determine progression (variability in any A, B, and C parameters ≥95% CI or any 2 parameters ≥80% CI). An increase of ≥1 diopter in corneal astigmatism and curvature parameters and a ≥2% reduction in thickness parameters constituted progressive disease. Two hundred seventy-seven eyes of 155 patients were included. The 2 baseline visit criteria identified the highest progression (n=186 [67.2%]), followed by the single baseline visit (n=158 [57%]), minimum corneal thickness (n=114 [41.2%]), central corneal thickness (n=111 [40.1%]), maximum keratometry (n=76 [27.4%]), corneal astigmatism (n=55 [19.9%]), back mean keratometry (n=50 [18.1%]), and front mean keratometry (n=31 [11.2%]) criteria. The median time to progression was shortest using the single baseline visit criterion (11 months), followed by the 2 baseline visits (11.6 months), minimum corneal thickness (12.1 months), maximum keratometry (12.3 months), corneal astigmatism (14.8 months), central corneal thickness (16.6 months), back mean keratometry (18.4 months), and front mean keratometry (24.4 months) criteria. In a subgroup analysis, progression could be identified 4 to 7 months earlier with the BAPD in eyes that were also progressive for maximum keratometry and central corneal thickness. BAPD detects progression at a higher rate and earlier than conventional parameters.

Repeatability of 2 swept-source OCT biometers and 1 optical low-coherence reflectometry biometer.

To compare the repeatability of 2 swept-source optical coherence tomography (SS-OCT) biometers, IOLMaster 700 (biometer A, Carl Zeiss Meditec AG) and ANTERION (biometer B, Heidelberg Engineering GmbH) and 1 optical low-coherence reflectometry (OLCR) device (biometer C, LENSTAR, LS900; Haag-Streit AG). Department of Ophthalmology, Hanusch Hospital, Vienna Institute for Research in Ocular Surgery-Karl Landsteiner Institute, Vienna, Austria. Prospective study that included patients scheduled for cataract surgery. Three consecutive measurements were performed with 2 SS-OCT devices and 1 OLCR device. The repeatability of the following biometry variables was compared: keratometry, central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), and axial eye length (AL). To assess the repeatability of each parameter, the within-subject SD (Sw) and coefficient of variation (CoV) were calculated. Fifty eyes of 50 patients were included. The CoV values were below 0.5 for all variables, except for ACD and LT for biometer C. The Sw values for mean keratometry were 0.018 for biometer A, 0.083 for biometer B, and 0.137 for biometer C. For the ACD, the Sw values were 0.039 and 0.004 for biometer A and biometer B, respectively, and 0.134 for biometer C. For the AL, the values were 0.006 for biometer A, 0.008 for biometer B, and 0.012 for biometer C. All biometry devices included in the analysis presented a high repeatability. The SS-OCT devices showed a higher repeatability performance compared with the OLCR device.

Ferrara Rings for Visual Rehabilitation in Eyes with Keratoconus and Previous Cross-Linking Using the Ferrara Ring Nomogram.

Purpose: To report the visual, refractive and tomographic outcomes following the implantation of intrastromal corneal ring segments (ICRS) (Ferrara rings, AJL Ophthalmics, Miñano, Spain) in eyes with a history of keratoconus and corneal cross-linking using the Ferrara ring nomogram. Methods: Retrospective, interventional case series performed at the Corneoplastics Unit, Queen Victoria Hospital, East Grinstead, United Kingdom. Results: 21 eyes of 19 patients with a history of keratoconus and prior corneal collagen cross-linking had Ferrara Intrastromal Corneal Ring Segments implanted between December 2015 and October 2017. The number, thickness and length of ring segments was chosen based on the Ferrara ring company nomogram. Mean uncorrected visual acuity (UDVA) improved from 0.88 to 0.52 logMAR (p < 0.001). Mean corrected visual acuity (CDVA) improved from 0.47 to 0.36 logMAR (p = 0.046). The percentage of eyes achieving 20/40 UDVA and CDVA increased from 5% to 38% and from 38% to 67%, respectively. Of the eyes, 52.3% gained at least two lines of CDVA. The spherical equivalent improved from −7.51D to −3.76D (p < 0.001) and the refractive astigmatism magnitude improved from 5.14D to 2.76D (p = 0.004). There were significant improvements in the corneal tomography with mean keratometry (KM) improving from 50.40D (3.53) to 48.24D (3.00) (p = 0.01) and keratometric astigmatism magnitude improving from 5.14D (2.91) to 2.76D (1.67) (p = 0.004). Conclusion: Insertion of Ferrara rings in keratoconic eyes with a history of prior cross-linking using the company nomogram results in significant improvements in visual, refractive and tomographic outcomes.