Moderate Keratoconus Research Articles

Effect of continuous intrastromal corneal ring (MyoRing) implantation on intraocular pressure measurements in patients with keratoconus

Purpose The aim of this study was to document the effect of implanting continuous intrastromal corneal ring (MyoRing) on intraocular pressure (IOP) measurements by Goldmann applanation tonometer (GAT). Patients and methods Patients with moderate keratoconus with keratometric (K) readings between 48 and 55 D, corneal thinnest location on pentacam of more than 380 μm, and clear cornea underwent MyoRing implantation using a femtosecond laser system as per standard care. IOP was measured over the central cornea using GAT at baseline and after surgery by 1 week, 1, and 6 months, with the readings of month 6 being used in statistical analysis. Results A total of 30 eyes of 30 patients were enrolled in the study. The mean preoperative IOP was 14.3 mmHg, whereas the mean postoperative IOP was 13.9 mmHg, with no statistical significance (P>0.05). The mean preoperative pachymetry at the center of the cornea was 442.4 μm, whereas the mean postoperative pachymetry at the center of the cornea was 438 μm, with no statistical significance (P>0.05). Conclusion Implantation of MyoRing in patients with keratoconus resulted in a mild decrease in IOP measurements that was neither clinically nor statistically significant.

An Analysis of Scheimpflug Holladay-Equivalent Keratometry Readings Following Corneal Collagen Cross-Linking.

Objectives:The aim of this research was to compare Holladay equivalent keratometry readings (EKR) and anterior corneal simulated keratometry (SimK) values in keratoconus cases following corneal collagen cross-linking (CXL) treatment.Methods:This study included 42 eyes of 30 patients with progressive keratoconus. Scheimpflug imaging was performed pre-CXL and at post-CXL months 6 and 12. The mean Holladay EKR and SimK measurements from 1mm to 7mm were compared and repeated variance analysis was performed.Results:The mean age of the patients was 18.93±3.82 years (range: 12-27 years). A reduction was observed in the EKR and SimK values at 6 and 12 months postoperatively compared with the preoperative values, but the difference was not statistically significant (p>0.05). In the mild keratoconus group, the keratometric measurements were lower after treatment. Similar measurements were obtained in the moderate and severe keratoconus groups before and after treatment. In 1 patient, there was an increase of >1 diopter in the maximum keratometry value. No complications developed that would lead to vision loss.Conclusion:Corneal collagen CXL treatment is known to be effective to a depth of two-thirds of the anterior corneal stroma. The results of this study showed that Holladay EKR measurements differed from SimK measurements, especially in cases of mild keratoconus. In addition to anterior corneal surface measurements, methods that can evaluate anterior and posterior surface curves could provide more accurate results in progression analysis.

Management of Keratoconus Using Myoring

Background: keratoconus (KC) is an ectatic condition of the cornea which is usually progressive and noninflammatory, affecting both eyes asymmetrically. It is characterized by stromal thinning that leads to corneal surface irregularity. Vision affection is due to irregular astigmatism and corneal scarring. Aim of the Work: assessment of the effectiveness of Myoring intreating patients with keratoconus. Patients and Methods: prospective non-randomized non-comparative clinically controlled study, Myoring was implanted for (20) eyes of 20 patients with progressive keratoconus. Results: visual acuity and corneal parameters improved significantly in all patients after one year postoperatively. Conclusion: Myoring when used in suitable patients has the potential to produce excellent long-term vision results in mild, moderate and advanced keratoconus cases, regardless of cone position and disease progression.

Management of Keratoconus Using Myoring

Background: keratoconus (KC) is an ectatic condition of the cornea which is usually progressive and noninflammatory, affecting both eyes asymmetrically. It is characterized by stromal thinning that leads to corneal surface irregularity. Vision affection is due to irregular astigmatism and corneal scarring. Aim of the Work: assessment of the effectiveness of Myoring intreating patients with keratoconus. Patients and Methods: prospective non-randomized non-comparative clinically controlled study, Myoring was implanted for (20) eyes of 20 patients with progressive keratoconus. Results: visual acuity and corneal parameters improved significantly in all patients after one year postoperatively. Conclusion: Myoring when used in suitable patients has the potential to produce excellent long-term vision results in mild, moderate and advanced keratoconus cases, regardless of cone position and disease progression.

Prevalence of ectatic corneal conditions among keratorefractive candidates

Background Noninflammatory corneal ectasias is a group of diseases including keratoconus (KC), pellucid marginal degeneration (PMD), and keratoglobus. KC is the most common form of corneal ectasia characterized by progressive thinning of the central or inferior cornea, causing corneal steepening and cone formation. The disease typically presents during the second decade of life and is bilateral, but often one eye precedes the other. Detecting the cases of subclinical KC had always been a challenge for refractive surgeons especially when the suggestive clinical signs and symptoms to differentiate subclinical KC from the normal are not observed. Aim The aim of the study is to determine the prevalence of ectatic corneal conditions among keratorefractive population admitted for refractive surgery at Al-Mashreq Eye Centre, during the period from June 2017 till December 2017, using data from the Scheimpflug tomographer imaging system. Patients and methods Our study was conducted on patients seeking consultation for refractive surgery at Al-Mashreq Eye Centre during the period from June 2017 to December 2017. We used the Pentacam device to screen 1439 refractive surgery candidates after being subjected to precise ocular examination and full general and ocular history taking. Results In our study, a total of 42 patients (84 eyes) showed topographic signs of manifest and subclinical KC, making a total prevalence of 3.0%. No cases with PMD or keratoglobus were found, but cases with KC having a topographic pattern mimicking PMD called pellucid-like KC were found in five eyes (three patients). Compound myopic astigmatism was the commonest refractive error in keratoconic eyes (71.4%). Conclusion Prevalence of KC in refractive population may reflect an approximate idea of its prevalence in general population. Meticulous examination before refractive surgery can forbid bad consequences in patients at high risk of developing post-laser-assisted in situ keratomileusis ectasia and may save patients discovered at mild or moderate KC stages from the ultimate fate of keratoplasty. Moreover, surgeons should be aware that hypermetropia and mixed astigmatism do not eliminate the possibility of an associated ectatic corneal disease.

Contribution of Fourier-domain optical coherence tomography to the diagnosis of keratoconus progression

To determine the anatomic criteria for diagnosing keratoconus progression by corneal optical coherence tomography (OCT). Quinze-Vingts National Ophthalmology Hospital, Paris, France. Prospective case series. Scanning-slit corneal topography (Orbscan II) and Fourier-domain corneal OCT (RTVue) were performed in eyes with mild to moderate keratoconus (progressive or nonprogressive [stable] ectasia) at each examination to assess the keratoconus. Disease progression was defined as an increase of at least 1.0 diopter (D) in the steepest keratometry (K) measurement over 6months. Of the 134 eyes of 134 patients with mild to moderate keratoconus, 98 had had progressive ectasia and 36 nonprogressive ectasia. The mean maximum K increased significantly in the progressive group (2.1 D ± 1.2 [SD], P<.0001) and remained constant in the stable group (-0.03±0.39 D, P=.31). The mean thinnest corneal thickness increased significantly in the progressive group (-7.98±9.3μm,P<.0001) and remained constant in the stable group (-0.52±4.21μm,P=.22). The change in maximum K was significantly correlated with changes in the thinnest corneal thickness (r=-0.61, P<.0001). A cutoff value of -5μm for the change in thinnest corneal thickness was identified on receiver operating characteristic curves as a threshold separating cases of progressive and stable keratoconus (area under the curve, 0.79; sensitivity, 68%; specificity, 89%). Topographic data partly reflected the structural changes occurring during the progression of corneal ectasia. Based on the pachymetric parameters provided by OCT, corneal and epithelial thinning was correlated with corneal deformation. The use of corneal OCT might therefore improve the diagnostic sensitivity for keratoconus progression.

Manual mid-stromal dissection as a low risk procedure to stabilize mild to moderate progressive keratoconus

BackgroundTo evaluate the efficacy of manual mid-stromal dissection in stabilizing progressive keratoconus.MethodsSurgeries were performed in 16 eyes of 14 patients with progressive keratoconus. All eyes were examined before and at 1 day, 1 week, 1, 3, 6 and 12 months after surgery, and every 6 months thereafter. Pentacam (simK, Kmax and pachymetry), best corrected visual acuity (BCVA) and subjective refraction were recorded up to the latest follow-up visit (mean follow-up time 6.6 ± 2.4 years).ResultsAll surgeries were uneventful, and no postoperative complications occurred. Keratometry values (n = 15) stabilized in 6/11 eyes (55%) with a preoperative Kmax < 60.0 diopter (D), while all eyes > 60 D showed continued progression. In 11/15 eyes (73%) pachymetry was unchanged. BCVA with spectacles remained stable in 7/12 eyes (58%) and improved ≥2 Snellen lines in 5/12 eyes (42%). BCVA with a contact lens remained stable in 4/9 eyes (44%), improved ≥2 Snellen lines in 3/9 eyes (33%) and deteriorated in 2/9 eyes (22%).ConclusionsManual mid-stromal dissection was effective in 50% of keratoconic corneas with Kmax values < 60 D and may be considered in cases ineligible for other interventions such as UV-crosslinking, stromal ring implantation or Bowman layer transplantation. An advantage of the procedure may be that the tissue is unaltered and that no synthetic or biological implant is required.

Objective and Subjective Outcome of Clear Lensectomy With Toric IOL Implantation After Corneal Collagen Cross-Linking in Selected Cases of Keratoconus.

To evaluate the visual and topographic outcomes of a two-stage approach treatment for selected cases of progressive keratoconus (KC); corneal collagen cross-linking (CXL) followed by phacoemulsification with toric intraocular lens (IOL) implantation. The study included 9 eyes of 6 patients diagnosed with progressive KC, aged from 35 to 47 years (41.6±11.2 years). All studied eyes underwent a two-stage approach treatment: first corneal collagen CXL followed after at least 6 months by phacoemulsification with foldable toric IOL implantation in both eyes of three patients and only one eye of the other three patients. A complete ophthalmological examination was performed preoperatively and postoperatively. Topographical and visual outcomes were evaluated during 1-year follow-up period. At baseline, seven eyes had mild and two eyes had moderate KC. Sphere ranged from -3.00 to -8.00 diopter (D) and cylinder from -3.50 to -5.50 D. All eyes could be corrected by glasses to 0.50 (log of minimal angle of resolution [logMAR]) or more. At 6 months after CXL, only Kmax decreased significantly from baseline, with no change in visual acuity or manifest refraction. After phacoemulsification with toric IOL implantation, sphere changed from -5.74±1.88 D preoperatively to 0.33±0.72 D 12 months postoperatively (P<0.001), and cylinder changed from -4.53±0.98 to -1.10±0.76 D (P<0.001). There was significant improvement in mean uncorrected distance visual acuity from logMAR 1.43±0.51 preoperatively to 0.30±0.09 postoperatively (P<0.001) and the mean corrected distance visual acuity (CDVA) from 0.34±0.12 preoperatively to 0.24±0.13 (P=0.03) 1 year after IOL implantation. All patients were satisfied with their visual improvement. This two-stage approach in selected cases of progressive KC is a safe and effective procedure regarding keratometric stability, and visual and refractive results.

Combined wavefront-guided transepithelial photorefractive keratectomy and corneal crosslinking for visual rehabilitation in moderate keratoconus

To present 24-month results from the transepithelial photorefractive keratectomy (PRK)-corneal crosslinking (CXL) trial using simultaneous accelerated CXL and a new tissue-saving ocular wavefront-guided transepithelial PRK algorithm aiming to reverse visual loss in early-stage keratoconus without compromise to stabilization of disease progression. Moorfields Eye Hospital, London, United Kingdom. Prospective case series. Patients with progressive grades I to III keratoconus and logarithm of the minimum angle of resolution (logMAR) corrected distance vision acuity (CDVA) worse than 0.00 (20/20) were included. Consecutive matched historical controls treated only with accelerated CXL were the control group. The main outcome measure was change in logMAR CDVA. The study group comprised 47 eyes of 47 patients (mean age 24.6years±3.8 [SD]). The CDVA improved from 0.28±0.21 logMAR (20/60) preoperatively to 0.15±0.14 logMAR (20/30) 24months after transepithelial PRK-CXL (P<.001). Twelve eyes gained and 1 eye lost 2 lines or more of CDVA. The mean stromal ablation depth at the cone apex was 35±15μm. Significant reductions in the maximum keratometry (K) reading and coma were evident in topographic comparison maps. The controls (n=47) had no significant changes in CDVA, higher-order aberrations, or K values. The mean K values in both groups were stable from 6months after treatment. Ocular wavefront-guided transepithelial PRK-CXL resulted in significant gains in CDVA without compromising CXL efficacy over a 24-month follow-up.

Retinal nerve fibre layer and ganglion cell complex thickness in patients with keratoconus

Background: Keratoconus, a corneal ectasia, is associated with corneal thinning and altered optical media. Consequently, assessment of the visual field, optic nerve head and intraocular pressure measurements may be challenging in patients with keratoconus. Few studies have investigated posterior segment variables including the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC) thickness in patients with keratoconus.Aim: To investigate RNFL and GCC thickness in patients with keratoconus.Methods: A comparative quantitative research design was used. The sample consisted of 56 participants (28 with mild, moderate or severe keratoconus, and 28 controls) who accessed the optometry clinic at the University of KwaZulu-Natal. There was an equal distribution of male (n = 14) and female (n = 14) participants in the keratoconus and control groups. Most participants were black (n = 34) or Indian (n = 18). Corneal power and refractive error were assessed with the Oculus Keratograph and subjective refraction respectively. The iVue-100 optical coherence topography device was used to measure RNFL and GCC thickness. Data were analysed by descriptive and inferential statistics.Results: The mean global RNFL thickness was slightly higher in the control group than the keratoconus group for the right (106 µm vs. 99 µm) and left (103 µm vs. 98 µm) eyes but these differences were not significant (p ≥ 0.057). For all RNFL quadrants, slightly lower mean RNFL measurements were found in the keratoconus group. The mean GCC thicknesses were marginally higher (3 µm – 6 µm) in the control group.Conclusion: The RNFL and GCC thickness differences between patients with keratoconus and controls are not clinically significant. Therefore, abnormally reduced RNFL and GCC thickness measurements in patients with keratoconus warrant further investigation for other pathologies specifically glaucoma.

Long-term database analysis of conventional and accelerated crosslinked keratoconic mid-European eyes.

To investigate the long-term efficacy of accelerated corneal collagen cross-linking (CXL) in a large mid-European cohort with progressive keratoconus. Four hundred thirteen eyes of 316 patients with progressive keratoconus were enrolled and treated with conventional (group A) or accelerated (group B) CXL. Uncorrected distance visual acuity(UDVA), correcteddistance visual acuity(CDVA), slit lamp, and Pentacam® examinations were performed before and 12, 24, and 36months after surgery. Maximum and mean anterior keratometry (Kmax, Kmf), corneal topography indices, and corneal pachymetry (TCT) were examined within each group and between groups. Further subgroup analysis of mild and moderate keratoconic eyes was performed. One hundred thirty-one eyes of 101 patients were treated in group A, 282 eyes of 215 patients in group B. (UDVA, CDVA) and Kmax improved within each group, but not statistically significantly between groups after 36months (p = 0.081, p = 0.344, p = 0.113, respectively). Kmf remained stable in both groups. TCT decreased significantly in group A (p = 0.014), but remained stable in group B (p = 0.063). Subgroup analysis showed similar results with improvement in visual acuity and keratometry and decrease of TCT. Corneal topography indices showed no differences between the groups after 36months, but developed differently in the subgroup analysis. No correlation was detected between the change of corneal topography indices and TCT with regard to preoperative Kmax. In a large mid-European study population including subgroup analysis of mild and moderate keratoconus, accelerated CXL showed similar results to conventional CXL regarding keratometry, corneal topography indices, and CDVA, but further improvement of UDVA. Preoperative Kmax did not affect the postoperative course of corneal topography indices and TCT.

Simultaneous intratunnel cross-linking with intrastromal corneal ring segment implantation versus simultaneous epithelium-off cross-linking with intrastromal corneal ring segment implantation for keratoconus management.

PurposeThe purpose of this study is to compare the efficacy of intratunnel cross-linking combined with intrastromal corneal ring segment (ICRS) implantation versus combined epithelium-off (epi-off) cross-linking and ICRS implantation for the management of keratoconus.MethodsOur study included 20 eyes of 12 patients with moderate-to-severe keratoconus. Group A included 10 eyes that underwent simultaneous ICRS implantation with intratunnel cross-linking. Group B included 10 eyes that underwent simultaneous ICRS implantation with epi-off cross-linking. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest sphere and cylinder, mean and maximum keratometric readings, corneal thickness at pachy apex and thinnest location, as well as corneal hysteresis (CH) and corneal resistance factor (CRF) were compared preoperatively and at 6 months postoperatively.ResultsThe mean UDVA and CDVA improved significantly in both groups with a statistically nonsignificant difference between the groups (P=0.798 and 0.126, respectively). The manifest cylinder decreased significantly in both groups, while the manifest sphere decreased significantly in Group A but nonsignificantly in Group B with a statistically nonsignificant difference between the groups (P=0.773 and 0.111, respectively). Both techniques led to significant flattening of the cornea and a significant decrease of Km and Kmax with a statistically nonsignificant difference between the groups (P=0.312 and 0.857, respectively). There was a statistically significant decrease in CH in both groups postoperatively; however, there was a statistically nonsignificant increase in CRF after both techniques with a statistically nonsignificant difference between the groups in the mean change of CH and CRF (P=0.633 and 0.313, respectively). No intraoperative or postoperative complications were observed in both groups.ConclusionBoth techniques improved the visual and refractive outcomes in cases of moderate and severe keratoconus with no statistically significant difference between the groups; however, simultaneous intratunnel cross-linking and ICRS implantation showed early visual rehabilitation due to the absence of epithelial defect.

Visual and topographic outcomes of accelerated corneal cross-linking in keratoconus: 1-year follow-up

Purpose The aim of this study was to evaluate the visual and topographic outcomes of accelerated corneal collagen cross-linking (ACXL) in mild and moderate progressive keratoconus. Patients and methods This retrospective study evaluated the visual and topographic outcomes of 54 eyes of 36 patients of progressive keratoconus who had ACXL (9 mW/cm; 10 min). Data were collected 12 months after corneal collagen cross-linking. Results Uncorrected distance visual acuity was improved from 0.84±0.49 logMAR preoperatively to 0.79±0.3 logMAR postoperatively which is not statistically significant (P=0.1). Corrected distance visual acuity was not significantly changed. The mean preoperative corrected distance visual acuity was 0.25±0.18 and 0.23±0.2 logMAR preoperatively and postoperatively, respectively (P=0.4). Manifest spherical equivalent was not significantly changed, from −4.1±2.77 D preoperatively to −4.02±2.4 D postoperatively, which was not statistically significant (P=0.4). There were no significant changes of steep K, flat K, average K, and Kmax compared with preoperative measurements at 12 months. Conclusion ACXL (9 mW/cm; 10 min) is effective in stabilizing the keratoconus at 1-year follow-up.

Two Years Follow up Evaluating Progression of Ectasia for Keratoconus Patients Treated with Simultaneous Topography - Guided PRK Plus Cross Linking

This retrospective study was designed to evaluate the efficacy and safety of simultaneous topography-guided PRK plus cross linking for patients with mild to moderate keratoconus and to evaluate the stability of the cone. The patients were evaluated over two years for the progression and stability of the cone by the Allegro Pentacam Oculyzer to assess the changes of corneal curvatures (K readings) and the stability of the cone after the surgery and evaluating uncorrected distance (UDVA) and best corrected (CDVA) visual acuities. The follow-up results showed that UDVA improved from 0.4±0.3 to 0.7±0.1 and CDVA changed from 0.6±0.1 to 0.8±0.1 (P < 0.001). The keratometry value decreased from 44.1±2.2 to 41.4±1.6 D for K1, and from 46.4±2.6 to 43.5±1.7 for K2 (P < 0.001). This combined procedure offers a promising method to stabilize the corneal surface with reducing higher order aberrations so enhancing quality of vision in keratoconus patients.

Visual rehabilitation in moderate keratoconus: combined corneal wavefront-guided transepithelial photorefractive keratectomy and high-fluence accelerated corneal collagen cross-linking after intracorneal ring segment implantation

BackgroundTo investigate the effects of combined corneal wavefront-guided transepithelial photorefractive keratectomy (tPRK) and accelerated corneal collagen cross-linking (CXL) after intracorneal ring segment (ICRS) implantation in patients with moderate keratoconus.MethodsMedical records of 23 eyes of 23 patients undergoing combined tPRK and CXL after ICRS implantation were retrospectively analyzed. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal indices based on Scheimpflug tomography, higher-order aberrations (HOAs), and corneal biomechanical properties were evaluated before and after ICRS implantation, and at 1, 3, and 6 months after combined tPRK and CXL.ResultsThere were significant improvements in final logMAR UDVA and logMAR CDVA, and reductions in sphere, MRSE, and all corneal indices from baseline. Significant improvements in logMAR UDVA and reductions in sphere, MRSE, maximal keratometry, keratometry at the apex, mean keratometry, and keratoconus index were noted after ICRS implantation. After tPRK and CXL, significant improvements in logMAR UDVA and logMAR CDVA, and reductions in cylinder and all corneal indices were observed. There were significant improvements in final root mean square HOAs and coma aberrations from baseline, but no changes from baseline after ICRS implantation. Significant reductions in final radius and deformation amplitude from baseline were noted.ConclusionsCombined tPRK and accelerated CXL after ICRS implantation in moderate keratoconus appears to be a safe and effective treatment, providing an improvement in visual acuity, corneal indices, and HOAs.Trial registrationretrospectively registered (identification no. NCT03355430). Date registered: 28/11/2017.

OPD scan III accuracy: Topographic and aberrometric indices after accelerated corneal cross-linking

PurposeTo determine topographic and aberrometric changes after accelerated cross-linking (ACXL; 18 mW/cm2 for 5 min) as measured with OPD Scan III (Nidek Inc., Tokyo, Japan) and their repeatability in patients with mild and moderate keratoconus (KCN). MethodsIn this prospective study, 25 eyes with mild KCN [Ksteep = 47.24 ± 3.11 diopter (D)] and 20 moderate cases (Ksteep = 52.86 ± 4.39 D) were examined under mesopic conditions (20 lux) twice, 30–45 min apart, at baseline and 6 and 12 months afterwards. Extracted indices were Ksteep, Kflat, ocular and corneal irregularity, ocular and corneal total higher order aberrations (HOAs), coma, trefoil, and spherical aberration (SA). Repeatability index (RI) and intraclass correlation coefficients (ICCs) were determined. ResultsIn mild cases, Ksteep and corneal irregularity had lower RI, but Kflat and ocular irregularity had higher RI (all P > 0.050) at 1 year. The RI for ocular total HOAs, coma, and SA decreased and showed no significant change for trefoil (all P > 0.050). Moderate cases showed non-significant increases in RI for Ksteep, Kflat, ocular and corneal irregularity (all P > 0.050), and all aberrometry indices, and significant increases in RI for ocular coma (P = 0.046) and corneal trefoil (P = 0.037). At 1 year, ICC was >0.75 for all indices except ocular and corneal trefoil (ICC = 0.613 and 0.390) in moderate cases. ConclusionsAt one year after ACXL, OPD Scan III showed acceptable repeatability in mild cases. In moderate cases, topographic indices had acceptable repeatability but poorer compared to the mild group. Overall, ocular HOAs showed better repeatability than corneal ones. These changes should be considered in the interpretation of measurements.

Correlation of Corneal Endothelial Cell Density with Corneal Tomographic Parameters in Eyes with Keratoconus.

Objectives:To examine changes in corneal endothelial cell density (ECD) in different stages of keratoconus and evaluate its correlation with corneal tomographic parameters.Materials and Methods:Two hundred six patients with keratoconus were enrolled in the study. Corneal topography was performed by Sirius (CSO, Italy), which has a rotating Scheimpflug camera and a Placido disc topographer. Automatic endothelial analysis was done with the non-contact endothelial microscope (20x probe) of Confoscan-4 (NIDEK, Japan). The eyes were classified into stages based on steepest keratometric value as follows: mild <45 D; moderate 45-52 D; severe >52 D and according to thinnest cornea thickness (TCT) as <400 μm, 400-450 μm, and >450 μm. Tomographic and endothelial cell parameters were compared among the groups using Kruskal-Wallis test and the correlations between them were analyzed using Spearman correlation.Results:The study included 391 eyes of 100 male (24.29±7.7 years, range 11-47 years) and 106 female (26.26±7.5 years, range 13-45 years) patients (p=0.07). Mean ECD values were 2628±262 cells/mm2, 2541.9±260.4 cells/mm2, and 2414.6±384.3 cells/mm2 in mild, moderate, and severe keratoconus, respectively (p<0.001) and 2592.3±277 cells/mm2, 2502±307 cells/mm2 and 2348±296 cells/mm2 in corneas with TCT values >450 µm, 400-450 µm, and <400 µm, respectively (p<0.001). ECD showed significant negative correlation with keratometric and elevation parameters and positive correlation with pachymetric parameters (p<0.05).Conclusion:As endothelial cell numbers seem to decrease with the progression of keratoconus, specular/confocal microscopy screening should be carried out, especially in eyes with advanced stages and corneas with TCT <400 µm.

Identifying more reliable parameters for the detection of change during the follow-up of mild to moderate keratoconus patients

BackgroundReaching a consensus on which parameters are most reliable at detecting progressive keratoconus patients with serial topography imaging is not evident. The aim of the study was to isolate the parameters best positioned to detect keratoconus progression using the Pentacam HR® measures based on the respective limits of repeatability and range of measurement.MethodUsing the Pentacam HR®, a tolerance index was calculated on anterior segment parameters in healthy and keratoconic eyes. The tolerance index provides a scale from least to most affected parameters in terms of measurement noise relative to that observed in healthy eyes. Then, based on the “number of increments” from no disease to advanced disease, a relative utility (RU) score was also calculated. RU values close to 1 indicate parameters best positioned to detect a change in keratoconic eyes.ResultsThe tolerance index values indicated that 36% of ocular parameters for keratoconic eyes had repeatability limits which were wider than normative limits (worse), but 28% of the ocular parameters were narrower than normative limits (better). Considering only those parameters with a RU greater than 0.95, a small number of parameters were within this range, such as corneal curvature and asphericity indices.ConclusionsThis study demonstrates that measurement error in keratoconic eyes is significantly greater than healthy eyes. Indices implemented here provide guidance on the levels of expected precision in keratoconic eyes relative to healthy eyes to aid clinicians in distinguishing real change from noise. Importantly maximal keratometry (Kmax), central corneal thickness (CCT) and thinnest corneal thickness (TCT) were highlighted as problematic indices for the follow-up of keratoconus in terms of repeatability.

Femtosecond assisted intracorneal segments implantation for mild to moderate keratoconus: long term results

PurposeTo describe the 2 year results of femtosecond assisted intracorneal segments implantation for the treatment of mild to moderate keratoconus with the use of a femtosecond laser.MethodsProspective case series including 4 eyes of 4 consecutive patients with keratoconus. Patients where implanted with KC Solutions intrastromal segments (IS). Patients’ assessment included visual acuity measurement, manifest refraction, clinical examination and corneal topography and tomography. IS implantation was scheduled in patients with unsatisfying corrected visual acuity (CDVA) and contact lens intolerance. Planning of the operation was done based on the topography and refraction based on nomogram provided by the IS manufacturer. IS were implanted in intracorneal pocket created with the FS200 femtosecond laser. Comparisons were made between pre‐ to postoperative values with the Wilcoxon signed‐rank test.ResultsPreoperative average steep keratometry was 48.45D (range 45.6 to 51.6), whereas at 2 years postoperatively it was 46.73 (44.8 to 48.7), (p&lt;0.05). Preoperatively corneal astigmatism on average was 4.95D (2 to 9.1) and refractive astigmatism was 3.94D (2 to 9), whereas postoperatively average corneal and refractive astigmatism was 2.75 (1.2 to 6) and 1.87 (range 0,5 to 5) (p&lt;0.05 in both comparisons). CDVA improved in all cases by 1 to 2 lines of Snellen visual acuity. Average spherical equivalent refraction was ‐3.22 (‐1.87 to ‐4.5) preoperatively, and postoperatively it was reduced to ‐1,81 (‐0.50 to ‐3,5) (p&lt;0.05). No statistically significant differences were found between the last and 6th month follow up results.ConclusionsAccording to our pilot long term study, Implantation of KC Solutions intrastromal segments with the aid of a femtosecond laser improved all patients’ topographic and refractive astigmatism, visual acuity and refraction.

Efficacy and Safety Comparison among Rigid Gas Permeable Contact Lens Correction for Keratoconus

Background: Rigid gas-permeable contact lenses (RGP CL) are commonly used to manage moderate tosevere keratoconus. The range of RGP CL type currently available for the successful optical correctionof keratoconus has greatly expanded. We compared the efficacy and safety of available RGP CL basedon visual acuity (VA), keratometry, comfort score, and adverse event.Methods: Literature search on RGP CL and keratoconus retrieved 37 citations from 2010-2015. Ninearticles were selected as relevant to our purpose.Results: All studies showed improvement of VA following RGP CL wearing. Greatest improvementwas seen in Rose K CL (.5 - .36) in naïve CL patient and Twinbel bevel toric in refitting CL patient(.22). All studies reported lower mean ΔK post fitting RGP CL than pre-fitting. Greatest difference ofmean ΔK pre and post-fitting was observed in YK lens (.72). The most comfortable lens was Rose K(91.5%) followed by Soper CL (87.9%) and Twinbel bevel toric (64.4%). Punctuate corneal stainingfound in a considerable amount with YK lens patient.Conclusion: Among 5 types of RGP CL available now for keratoconus, Rose K provided greatestBCVA improvement in naïve CL patient whereas Twinbel bevel toric in refitting patient. YK lensgave greater changes in keratometry post-fitting RGP CL. The most comfortable lens for patient isRose K lens. The most common adverse event of CL wear is punctuate corneal staining in YK lenspatient.Keywords: rigid gas permeable contact lens, keratoconus