Moderate Keratoconus Research Articles

Two-year Outcomes of Transepithelial Customized Cross-linking for Mild to Moderate Keratoconus

Two-year Outcomes of Transepithelial Customized Cross-linking for Mild to Moderate Keratoconus

Accelerated corneal crosslinking with 20'-soaking hydroxypropyl methyl cellulose/riboflavin vs conventional crosslinking with 30'-soaking dextran/riboflavin.

To evaluate and compare functional and structural outcomes of accelerated corneal crosslinking (A-CXL) using riboflavin with hydroxypropyl methyl cellulose (HPMC) vs conventional corneal crosslinking (C-CXL) using riboflavin with dextran. American University of Beirut Medical Center, Beirut, Lebanon. Retrospective analysis. Retrospective analysis of 83 eyes of 73 patients with mild to moderate keratoconus. First group (n = 44 eyes) underwent C-CXL using a 30-minute riboflavin/dextran soaking between June 2014 and March 2016. Second group (n = 39 eyes) underwent A-CXL using a 20-minute riboflavin/HPMC soaking between April 2016 and December 2017. Patients were evaluated preoperatively and at 1, 3, and 12 months postoperatively. Main outcome measures were simulated keratometry (simK), maximum axial keratometry (Kmax), demarcation line depth, and haze intensity measured using optical coherence tomography-based image analysis software. Demarcation line (DL) was 298.30 ± 64.60 μm and 335.61 ± 99.76 μm for C-CXL and A-CXL groups, respectively ( P = .04). Haze profile was similar for both groups. The mean simK values were reduced from 46.93 ± 3.50 and 46.44 ± 2.93 preoperatively to 46.18 ± 3.65 and 45.54 ± 2.78 at 12 months postoperatively, for C-CXL and A-CXL, respectively ( P = .003 for both groups). The mean Kmax decreased from 52.46 ± 4.82 and 51.50 ± 3.87 preoperatively to 51.30 ± 4.42 and 50.30 ± 3.52 postoperatively, for the C-CXL and A-CXL, respectively ( P < .001 for both groups). There was no difference in the simK and Kmax changes between the C-CXL and A-CXL groups ( P = .814 and P = .913), visual acuity, and refraction between the 2 groups ( P > .05). A-CXL with a 20-minute riboflavin/HPMC soaking produced deeper DL and similar corneal haze, topographic, refractive, and visual results to C-CXL with a 30-minute riboflavin/dextran soaking.

Analysis of Cytokine and Chemokine Level in Tear Film in Keratoconus Patients before and after Corneal Cross-Linking (CXL) Treatment.

Keratoconus (KC) is a degenerative corneal disorder whose aetiology remains unknown. The aim of our study was to analyse the expressions of cytokines and chemokines in KC patients before and after specified time intervals after corneal cross-linking (CXL) treatment to better understand the molecular mechanisms occurring before and after CXL in KC patients process of corneal regeneration.; Tear samples were gathered from 52 participants immediately after the CXL procedure and during the 12-month follow-up period. All patients underwent a detailed ophthalmological examination and tear samples were collected before and after CXL at regular intervals: 1 day before and after the surgery, at the day 7 visit, and at 1, 3, 6, 9, and 12 months after CXL. The control group consisted of 20 healthy people. 10 patients were women (50%) and 10 were men (50%). The mean age was 30 ± 3 years of age. Tear analysis was performed using the Bio-Plex 3D Suspension Array System. Corneal topography parameters measured by Scheimpflug Camera included: keratometry values (Ks, Kf), PI-Apex, PI-Thinnest, Cylinder.; All the 12 months post-op values of the KC patients' topographic measurements were significantly lower than the pre-op. As for the tear cytokine levels comparison between the patient and control groups, cytokine levels of TNF-α, IL-6, and CXCL-10, among others, were detected in lower amounts in the KC group. The pre-op level of IL-6 exhibited a significant increase the day after CXL, whereas comparing the day after the procedure to 12 months after CXL, this showed a significant decrease. Both TNF-α and IL-1 showed a significant decrease compared to the day before and after CXL. We observed significantly higher levels of IL-1β, IL-10, IFN-γ and TNF-α in moderate and severe keratoconus than in mild keratoconus (p < 0.05). We also demonstrated a statistically significant positive correlation between both pre-op and 12 months after CXL TNF-α, IFN-γ, IL-6 and Ks and Kf values (p < 0.05, r > 0); Alterations of inflammatory mediators in tear fluid after CXL link with topographic changes and may contribute to the development and progression of KC.

Assessing progression limits in different grades of keratoconus from a novel perspective: precision of measurements of the corneal epithelium

BackgroundTo assess repeatability and reproducibility of corneal epithelium thickness (ET) measured by a spectral-domain optical coherence tomographer (SD-OCT)/Placido topographer (MS-39, CSO, Florence, Italy) in keratoconus (KC) population at different stages, as well as to determine the progression limits for evaluating KC progression.MethodsA total of 149 eyes were enrolled in this study, with 29 eyes in the forme fruste keratoconus (FFKC) group, 34 eyes in the mild KC group, 40 eyes in the moderate KC group, and 46 eyes in the severe KC group. Employing the within-subject standard deviation (Sw), test-retest variability (TRT), coefficient of variation (CoV), and intraclass correlation coefficient (ICC) to evaluate intraoperator repeatability and interoperator reproducibility.ResultsThe repeatability and reproducibility of MS-39 in patients with KC were acceptable, according to ICC values ranging from 0.732 to 0.954. However, patients with more severe KC and progressive peripheralization of the measurement points had higher TRTs but a thinning trend. The current study tended to set the cut-off values of mild KC, moderate KC, and severe KC to 4.9 µm, 5.2 µm, and 7.4 µm for thinnest epithelium thickness (TET). When differences between follow-ups are higher than those values, progression of the disease is possible. As for center epithelium thickness (CET), cut-off values for mild KC, moderate KC, and severe KC should be 2.8 µm, 4.4 µm, and 5.3 µm. This might be useful in the follow-up and diagnosis of keratoconus.ConclusionsThis study demonstrated that the precision of MS-39 was reduced in measuring more severe KC patients and more peripheral corneal points. In determining disease progression, values should be differentiated between disease-related real changes and measurement inaccuracies. Due to the large difference in ET measured by MS-39 between various stages of disease progression, it is necessary to accurately grade KC patients to avoid errors in KC clinical decision-making.

Compensatory Corneal Epithelial Changes After Femtolaser - Assisted Intracorneal Rings Implantation in Early and Moderate Cases of Keratoconus.

To study the compensatory corneal epithelial changes after femtolaser-assisted intracorneal ring segment (ICRS) implantation in early and moderate cases of keratoconus (KC) using anterior segment optical coherence tomography (AS-OCT). A prospective observational non-randomized study of 40 eyes with mild to moderate KC received femtolaser-assisted ICRS implantation. Ferrara ICRS with different arc lengths and thicknesses were used according to the patients' tomographic pattern. Patients had a clear central cornea, keratometry reading < 60 diopters, and corneal thickness > 400 microns. AS-OCT was performed preoperatively and at 1, 3, and 6 months after surgery. Corneal epithelial thickness (CET) was measured over 17 points (2 mm central and 16 points on 2-5 mm and 5-7 mm annular zones) over the pupil center. All data were collected and analyzed. Comparing the preoperative and postoperative data, there was a statistically significant increase in the CET postoperatively throughout the 6-month follow-up period in all zones (p<0.001). The epithelial thickness (ET) was noticed shortly around and central to the ring ridges by the first month (5-7 mm zone). By the third month, the flattened central cornea (2 mm zone) and the 2-5 mm zone showed a significant increase in ET up to the 6th month. ICRS implantation in KC results in a thicker and more regular epithelium in the central corneal zone as a secondary response to the corneal stromal changes induced by the implants.

Performance of Corvis ST Parameters Including Updated Stress-Strain Index in Differentiating Between Normal, Forme-Fruste, Subclinical, and Clinical Keratoconic Eyes

PurposeThis study seeks to evaluate the ability of the updated stress strain index (SSIv2) and other Corvis ST biomechanical parameters in distinguishing between keratoconus with different disease stages, and normal eyes. DesignDiagnostic accuracy analysis to distinguish disease stages. Methods1084 eyes were included and divided into groups of normal (199 eyes), forme fruste keratoconus (FFKC, 194 eyes), subclinical keratoconus (SKC, 113 eyes), mild clinical keratoconus (CKC-I, 175 eyes), moderate clinical keratoconus (CKC-II, 204 eyes) and severe clinical keratoconus (CKC-III, 199 eyes). Each eye was subjected to a Corvis ST examination to determine the central corneal thickness (CCT), biomechanically corrected intraocular pressure (bIOP), SSIv2 and other eight Corvis parameters including the SSIv1, SP-A1, A1T, ARTh, IIR, DAM, DARatio2 and CBI. The sensitivity and specificity of these parameters in diagnosing keratoconus were analyzed through receiver operating characteristic curves. ResultsBefore and after correction for CCT and bIOP, SSIv2 and ARTh were significantly higher, and IIR and CBI were significantly lower in the normal group than in the FFKC group, SKC group and the 3 CKC groups (all P<0.05). There were also significant correlations between the values of SSIv2, ARTh, IIR, CBI and the CKC severity (all P<0.05). AUC of SSIv2 was significantly higher than all other Corvis parameters in distinguishing normal eyes from FFKC, followed by IIR, ARTh and CBI. ConclusionCorvis ST's updated SSI demonstrated superior performance in differentiating between normal and keratoconic corneas, and between corneas with different keratoconus stages. Similar, but less pronounced, performance was demonstrated by the IIR, ARTh and CBI.

Outcomes of two different treatment modalities in mild to moderate keratoconus

PurposeTo describe visual and refractive outcomes of intrastromal corneal ring segments (ICRS) and toric implantable collamer lenses (TICL) implantation in cases of mild and moderate keratoconus.MethodsA prospective descriptive interventional case series. 40 eyes were allocated into two groups. First group (20 eyes) was treated with corneal collagen crosslinking (CXL) 1 month after ICRS implantation and the second group was treated using TICL after 1 year of CXL.ResultsBoth groups showed statistically significant improvement in spherical equivalent, cylindrical refraction, uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) over the follow-up period.ConclusionBoth ICRS and TICL are effective in treatment of mid and moderate keratoconus with more predictable visual results with TICL.

Comparison of Hybrid Contact Lenses and Rigid Gas-Permeable Contact Lenses in Moderate and Advanced Keratoconus.

We aimed to compare the clinical results and topographic data of the new generation hybrid contact lens (HCL) and rigid gas-permeable contact lens (RGPCL) in patients with moderate and advanced keratoconus. In this prospective study, HCL users comprised group 1 and RGPCL users comprised group 2. Snellen uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and lens-corrected visual acuity (LCVA); manifest spherical-cylindrical values; corneal topography measurements (flat keratometry [K1], vertical keratometry [K2], mean K, maximum K [Kmax], central corneal thickness [CCT], and thinnest corneal thickness [TCT]); and cone location were recorded. The study included 83 eyes of 51 patients in group 1 and 61 eyes of 40 patients in group 2. The groups were similar in age and gender (p>0.05). Mean LCVA (logMAR) was significantly lower than BCVA in both groups (p<0.001). The mean visual gain with contact lenses (Snellen chart) was 3.4±1.8 lines in group 1 and 4.0±2.1 lines in group 2. There was no significant difference between the two groups in BCVA, LCVA, or lines gained (p>0.05). There was also no significant difference between the two groups in terms of keratoconus stages, mean Kmax, CCT, TCT, or cone location (p>0.05), while mean UCVA (logMAR) and mean K were higher in group 2 (p<0.05). In both groups, the visual gain with lenses was higher in eyes with central cones, and there was significantly greater visual increase in group 2 (p=0.039). In moderate and advanced keratoconus, HCLs improved vision as much as RGPCLs and both lenses were more effective for central cones. Nevertheless, longer term of follow-up and larger numbers of patients are needed for long term follow-up results of HCL.

The effect of accelerated pulsed high-fluence corneal cross-linking on corneal endothelium; a prospective specular microscopy study

BackgroundCorneal collagen cross-linking (CXL) is a procedure utilized for halting keratoconus progression with different approved protocols. The current study aimed to assess the corneal endothelial changes following the relatively new accelerated pulsed high-fluence protocol of epithelium-off corneal cross-linking for the treatment of mild to moderate keratoconus.MethodsThis prospective case series study enrolled 45 eyes of 27 patients with mild to moderate progressive keratoconus who underwent accelerated pulsed high-fluence CXL (pl-ACXL, 30 mW/ cm2 UVA at 365 nm wavelength, 8 min pulsed mode 1 s on / 1 s off with a total energy of 7.2 J/ cm2). The main outcome measures were corneal endothelial changes assessed by specular microscopy at 3 and 6 months postoperatively including endothelial cell density (ECD), coefficient of variation, percentage of hexagonal cells, average, minimum and maximum endothelial cell sizes. Demarcation line depth was assessed 1 month following surgery.ResultsThe mean age of the studied sample was 24.89 ± 7.21. The mean preoperative ECD (2944.6 ± 247.41 cell/mm2) showed non-significant reduction at 3 and 6 months postoperatively (2931.03 ± 253.82 and 2924.7 ± 224.88 cell/mm2, respectively, P-value = 0.361). There were no significant changes in the mean coefficient of variation, percentage of hexagonal cells, average, minimum and maximum endothelial cell sizes at 3 and 6 months following pl-ACXL (P-value > 0.05). The mean demarcation line depth 1 month after pl-ACXL was 214 ± 17.43 μm.ConclusionsCorneal endothelial changes following accelerated pulsed high-fluence CXL were minimal with stability of endothelial cell count and non-significant morphological changes.Trial RegistrationClinicaltrials.gov: NCT04160338 (13/11/2019).

Measuring the agreement of keratometry readings of four devices in eyes with keratoconus.

To determine the keratometry measurement agreement using Sirius corneal topography and Scheimpflug camera, Tomey corneal topography, Topcon autokeratorefractometer, and Tomey OA-2000 optical biometry in eyes with different severity of keratoconus. In this retrospective study 115 eyes in different stages of keratoconus were divided into 2 groups of mild (stage 1), and moderate to severe keratoconus (stages 2, 3), according to the Amsler-Krumeich classification. Keratometry measurements were obtained using Sirius corneal topography and Scheimpflug camera (phoenix V3.7.01.08), Tomey corneal topography (Tms SW22C-200S-200), Topcon autokeratorefractometer (KR8900), and Tomey optical biometry (OA-2000 Opt-Meas V.4E). In group 1 All devices demonstrated fair agreement in average keratometry values (95% LoA range > 1 D). However, it was poorer for group 2 (95% LOA range > 3 D). In group 1 Bonferroni test revealed statistically significant difference in average K readings among (Topcon autokeratorefractometer 8900 and Tomey OA-2000 biometry, p < 0.01), and between (Tomey topography and Topcon autokeratorefractometer, p < 0.05). Also in group 2 significant difference was observed in the average keratometry of the most instruments (p < 0.01) except for the (Tomey topography and Topcon autokeratorefractometer) and (Tomey topography and Tomey OA-2000 biometry. According to our investigation in mild, moderate and severe keratoconus the agreement in K reading between Topcon autokeratorefractometer, OA-2000 optical biometry, Sirius topography and Tomey topography was poor. The agreement declines especially in the steep meridian and it was not acceptable clinically. These devices should not be applied interchangeably.

The Keratectasia Volume (KEV) in Corneal Topography to Evaluate the Effect of Corneal Collagen Cross-linking in Pediatric Keratoconus.

The study aimed to evaluate the keratectasia volume (KEV) before and after corneal cross-linking (CXL) in pediatric patients. This study included 40 eyes of 25 pediatric patients (10-19years) undergoing standard CXL. The support vector machine (SVM) algorithm was applied to transform mass pixels in corneal topography into a three-dimensioned model to calculate the KEV. The KEV, Kmax, K1, K2, Kave, keratectasia area (KEA), and thinnest corneal thickness (TCT) were determined before CXL and at 3, 6, and 12months after surgery. The correlation between KEV and other parameters (Kmax, TCT, max decentration, eccentricity, and so on) was calculated. The KEV was 4.75 ± 0.74 preoperatively and 4.43 ± 1.22 postoperatively at last follow-up (p < 0.002). There was strong positive correlation between the KEV and Kmax (r = 0.806, p < 0.0005). The preoperat ive KEV was 4.32 ± 0.69 in mild to moderate keratoconus (Kmax < 58D) and 5.27 ± 0.37 in advanced keratoconus (Kmax > 58D) (p < 0.0005, t-test). Postoperative KEV and K readings remained stable at the early stage, and the KEV showed a more drastic decreasing trend than Kmax at sixth month. Statistical significance was found in the KEV between preoperative and 6months after surgery (p < 0.0005), but not in Kmax and other parameters. In 83.3% (15 eyes out of 18 eyes) of the eyes, the preoperative KEV was greater than 4.6 in patients with significant flattening after CXL. Compared with K readings, the KEV can be regarded as a more sensitive index to evaluate the postoperative morphological changes after CXL in pediatric patients.

Forward-scattered and backward-scattered light in moderate keratoconus.

To evaluate the backscattered light, objective scatter index (OSI) and retinal straylight in patients with moderate keratoconus and healthy control subjects. A prospective observational study was developed with 33 patients in the moderate-keratoconus group (KC) and 34 in the non-keratoconus group (NKC). Corneal densitometry was obtained using Scheimpflug corneal tomography and measurements were expressed in grayscale units (GSU) over four zones within a 12.00 mm diameter around the corneal apex. A straylight meter was used to determine the amount of intraocular straylight under scotopic conditions, and the straylight parameter (LOG(s)) and test duration were recorded. The Optical Quality Analysis System based on the double-pass technique determined the OSI value. Significant differences were observed between the KC and NKC groups for corneal densitometry (except in the 6-10 mm zone), OSI and retinal straylight. A moderate and significant correlation was found between OSI and retinal straylight LOG(s) (r=0.52, p=0.002). Weaker and non-significant correlations were found between corneal densitometry and the other parameters analysed (i.e., OSI, retinal straylight LOG(s) and retinal straylight times). Backscattered light, retinal straylight and the OSI show clear differences between healthy eyes and those with moderate KC. The changes present in the stages of KC evaluated in the current study (stages II and III according to the Amsler-Krumeich classification) might alter the scattering of the light entering the eye.

Intrastromal corneal ring segments implantation with the aid of a femtosecond laser in cases of mild to moderate keratoconus: A 3‐year study

AbstractPurpose: To evaluate the 3‐year results of femtosecond assisted intrastromal corneal ring segments (ICRS) implantation for the treatment of mild to moderate keratoconus.Methods: Prospective case series including 4 eyes of 4 consecutive patients with keratoconus.Each patient was implanted with ICRSs according to the preoperative topography and refraction. The segments were implanted in intracorneal pocket created with the FS200 femtosecond laser. Planning of the operation was done based on the nomograms provided by the manufacturer. Patients' follow‐up involved visual acuity measurement, refraction control, clinical examination, corneal topography (Pentacam and Orbscan) and anterior segment OCT. The operation was performed due to patients' unsatisfying spectacle corrected visual acuity and contact lens intolerance.Results: Preoperative average steep keratometry was reduced from 53,3D (range 50.7–55.7D) to 48.6D (range 46.9‐50D) 3 years postoperatively. Preoperative average topographic astigmatism was 5.35D (range 4.2–7.9D) while postoperative was 2.7D (range 0.7–4.3D). Refraction assessment showed reduction of the refractive astigmatism from 3.5D (range 2.0–5.0D) to 2,5D (range 0.5–3.75D) and improvement of spherical equivalent from −5.0D (range − 4.0 to −7.25D) preoperatively to −2.5D (range −1.25 to −3.25D) 3 years postoperatively. Average pre‐op spectacle corrected visual acuity was 4/10, when post‐op visual acuity assessment on Snellen scale showed average improvement by 2 lines (range from 0 to 5 lines).Conclusions: The femtosecond assisted ICRS implantation based on the results of our study, improved all patients' visual acuity, topographic and refractive parameters 3 years postoperatively.

Comparison of anterior segment parameters in normal and keratoconus eyes using combined placido-disk schiempflug imaging-based topography

The aims: The purpose of this study was to evaluate and compare the anterior and posterior corneal surface parameters, keratoconus indices, thickness profile data, and data from enhanced elevation maps of keratoconus and normal corneas using Combined Placido-Schiempflug imaging-based topography, and to determine the sensitivity and specificity of these parameters in discriminating keratoconus from normal eyes.&#x0D; Materials and methods: A retrospective comparative observational study of 100 normal eyes and 100 keratoconus eyes was done from April 2014 to May 2015 at MM Joshi Eye Institute, Hubli, Karnataka. We evaluated and compared the anterior and posterior corneal surface parameters, keratoconus indices, thickness profile data, and data from enhanced elevation maps of keratoconus and normal corneas using Combined Placido-Scheimpflug Imaging based Topography to determine the sensitivity and specificity of these parameters in discriminating keratoconus from normal eyes.&#x0D; Results: Keratoconus indices (Sif, Sib, BCV-f, BCV-b, KVf, KVb, CCT, MinCT) showed Excellent AUROC values followed by K- steep in posterior curvature at 3 mm, 5 mm followed by K- steep in anterior curvature and other parameters in discriminating Normal from Keratoconus-Suspect eyes. Elevation indices- BCV-f, BCV-b, CCT, Min-CT, K-steep &amp; K-flat in anterior and posterior curvature in 3 mm, 5 mm, 7 mm, and CV were significant in discriminating normal from mild keratoconus. All parameters except ACV and ICA were significant in discriminating normal from moderate keratoconus. All parameters were significant in discriminating normal from severe keratoconus eyes. Morphological indices were significant in differentiating mild, moderate and severe keratoconus.&#x0D; Conclusion: Many parameters were statistically significant between keratoconus and normal eyes compared with early keratoconus eyes.&#x0D; The topography and corneal aberration results in this study are promising for detecting ectatic corneas. In our study, thickness indices-CCT, MinCT, Abberometry indices- BCVf, BCVb and keratometry in steep meridian at posterior curvature had the highest AUC scores in differentiating normal from sub-clinical keratoconus.&#x0D; Elevation indices- Rbf-f, Rbf-b, thickness indices- CCT, MinCT, aberrometry indices, and keratometry-steep in anterior &amp; posterior curvature had the highest AUC scores in differentiating moderate and severe keratoconus

Diagnostic value of corneal higher-order aberrations in keratoconic eyes.

This study aimed to investigate the diagnostic value of corneal anterior, posterior, and total higher-order aberrations in keratoconic eyes. We enrolled 94 patients (152 eyes) with mild keratoconus (Group 1), 64 patients (101 eyes) with moderate keratoconus (Group 2), and 32 patients (52 eyes) with advanced keratoconus (Group 3) according to the Amsler-Krumeich classification system; 99 healthy controls (197 normal eyes) were likewise enrolled. Anterior, posterior, and total corneal higher-order aberrations were assessed using a rotating Scheimpflug camera. The 3rd-order and 4th-order root-mean-square values were calculated for higher-order aberrations, including coma, spherical, and trefoil aberrations. Differences between keratoconic and normal eyes were analyzed using Kruskal-Wallis tests. Receiver operating characteristic curves were evaluated for the keratoconus and control groups. The differences in coma 90, coma, trefoil, and spherical aberrations, as well as 3rd-order and 4th-order root-mean-square values, were statistically significant between the keratoconus and control groups for all anterior, posterior, and corneal aberrations. The absolute values of these higher-order aberrations were higher in the keratoconus groups than in the control group and increased with keratoconus severity in Groups 1-3. Coma and 3rd-order RMS values showed excellent sensitivity and specificity for discriminating between normal and keratoconus eyes for all anterior, posterior, and corneal aberrations. Coma aberrations and 3rd-order root-mean-square values may be valuable for diagnosing keratoconus. Combining these data with topography information may enable the effective and efficient detection of keratoconus in the future.

Influence of Specialty Contact Lens Wear on Posterior Corneal Tomography in Keratoconus Subjects.

To evaluate the effect of specialty contact lens (CL) wear on posterior corneal tomography in keratoconus subjects. Patients with keratoconus who were wearing specialty CL were included in this retrospective cohort study. Tomographic parameters were evaluated with Scheimpflug imaging (Pentacam HR) before lens fitting and immediately after removal of CLs worn habitually for a period of several months. Subjects were divided into groups, according to type of lens (corneal, scleral, and hybrid) and keratoconus severity based on Belin/Ambrosio D (BAD-D) score, for further analysis. Thirty-four eyes of 34 subjects diagnosed with keratoconus were included. Mean duration of habitual CL wear was 7.0±0.3 months. For the entire cohort, a small increase in flat keratometric reading at the anterior corneal surface (K1F; P =0.032) and at the posterior surface (K1B; P =0.041) was found. In the corneal CL group (10 eyes; 29.4%), flattening of the anterior corneal curvature was detected (K max ; P =0.015). An increase in K1B value was seen in the scleral CL group (15 eyes; 44.1%) ( P =0.03). Combined topometric indices showed a small but significant difference in the entire cohort ( P <0.05) and in the subgroups of corneal CL wear and of moderate keratoconus (BAD-D score≥7). Various types of specialty CLs exert a differential influence on corneal parameters. A small steepening of keratometry at the posterior surface (K1B) was observed in the scleral lens group. Although corneal lens wear flattens the anterior cornea (K max ), it does not significantly alter the posterior corneal surface.

Decrease in Tear Film Lipid Layer Thickness in Patients with Keratoconus.

Keratoconus (KC) is a progressive corneal disorder characterized by thinning and protrusion, mostly of the inferotemporal and central corneal regions. Dysfunction of the meibomian gland, the excretions of which form the lipid layer of the tear film, has been reported to be associated with KC. Thus, this manuscript investigates the correlation among lipid layer thickness (LLT), partial blink rate (PBR), and KC of different degrees. This retrospective study included 54 patients and 24 healthy controls. The anterior corneal curvature, LLT, and PBR were taken from the unilateral eye of all 78 participants. The difference in those ocular parameters between the moderate and severe groups and the control group is significant. No significant association was found between anterior corneal curvature and LLT (r = −0.2, p = 0.15) across all the patients. However, there was a significant negative correlation between anterior corneal curvature and LLT in moderate (r = −0.6, p < 0.05) and severe (r = −0.7, p < 0.05) keratoconus cases. The results also show a significant negative correlation between anterior corneal curvature and PBR (r = −0.41, p < 0.05). Therefore, we conclude that the severity of keratoconus is associated with the thinning of LLT and the reduction of PBR. This may relate to a further epithelial abnormality with the reduced protection of tear film from the air, leading to the release of proteolytic enzymes that degrade stromal collagen and weaken the cornea.

Keratometric Outcomes after Simultaneous versus Sequential Intracorneal Ring Segment Implantation with Femtosecond Laser and Corneal Collagen Crosslinking in Egyptian Patients with Keratoconus and Ectasia.

Keratoconus (KC) is degenerative corneal disorder, with central and paracentral thinning and corneal ectasia. For KC progressive cases, primary treatment included corneal collagen cross linking (CXL) to stabilize coning and intracorneal rings segment (ICRS) to correct visual acuity. The aim of the study is to assess efficacy and safety of ICRS and CXL on one session (Simultaneous) or two sessions (sequential) with maximum of 1 month apart. This Prospective Intervention Comparative research made at Armed forces hospital, Cairo, Egypt from January 2017 to December 2019. Forty patients (60 eyes) with mild to moderate KC were enrolled. Patients sorted into Simultaneous group includes 21 patients (30 eyes) undergo two procedures (ICRS then CXL) at the same session and Sequential group included 19 patients (30 eyes) undergo ICRS then CXL on two sessions with month apart. Patients followed up at end of 1st, 3rd, and 6th months. Assessment included changes in corrected corneal surface irregularities as minimum keratometric 1 (K1), maximum keratometric readings (K2), and mean keratometric (Km) readings. Improvement of K1, K2, and Km in Simulations and Sequential groups achieved at end of 1st-, 3rd-, and 6th-month postoperative versus preoperative. Maximum improvement in Simulations and Sequential groups in K1 achieved at end of 6th and 1st months, in K2 at end of 3rd and 6th months and in Km at end of 1st and 3rd months. Combined ICRS and CXL act safely in one or two sessions and there are no statistically significant variations between results on both methods in keratometric readings.

Impact of rigid gas-permeable contact lens on keratometric indices and corneal thickness of keratoconus eyes examined with anterior segment optical coherence tomography.

Purpose/AimDetecting keratoconus (KC) progression helps determine the surgical indication for corneal cross-linking (CXL). This retrospective observational study aimed to examine changes in keratometric indices and corneal thickness in patients with KC who used rigid gas-permeable (RGP) contact lenses.Materials and methodsThis study involved 31 eyes (31 patients) diagnosed with KC. No patient had used RGP or any other type of contact lenses for at least 1 month. Corneal topographic data were obtained using three-dimensional anterior segment optical coherence tomography before and after >1 month of RGP lens use.ResultsThe average and maximum keratometry values changed after using an RGP lens (-1.05 ± 1.92 D, p < 0.01 and -1.65 ± 4.20 D, p = 0.04, respectively); the spherical component of the anterior corneal surface became significantly smaller (p = 0.02). No change was observed in the central or thinnest corneal thickness values. Keratometric changes were greater in eyes with severe KC than in those with moderate KC (p = 0.014).ConclusionsKeratometry and spherical components of the anterior corneal surface values decreased after RGP lens use; keratometric changes were greater in eyes with severe KC than in those with moderate KC. Corneal progression indices, including corneal thickness, posterior keratometry, and irregular astigmatism values, mostly remained unchanged. It is important to consider these findings when evaluating corneal topography of KC and preparing CXL.

Topographic Pattern of Keratoconus patient at First Presentation in Tertiary Eye Hospital of Bangladesh

Objective: To evaluate the topographic pattern of keratoconus patient at first presentation in a tertiary eye hospital of Bangladesh.&#x0D; Methods: This was a cross sectional study conducted over 200 eyes of 100 keratoconus patients attending at National Institute of Ophthalmology &amp; Hospital, Dhaka, for a period of 6 months. Selected patients underwent detail history, ocular and systemic examination as well as related investigations which includes corneal topography, keratometry and auto refractometry.&#x0D; Results: Mean age of the patients was 21.24 ± 6.25(SD) years and among the patients male predominance was observed, male to female ratio was 2.1:1. The mean unaided visual acuity of better eye was 0.86 ± 0.38(SD) Log MAR and mean unaided visual acuity of worse eye was 1.16 ± 0.44 Log MAR. Among 200 eyes there were 36 mild (18.0%), 100 moderate (50.0%) and 64 severe (32.0%) keratoconus eyes. Majority of the eyes (81.0%) showed three common topographic pattern, these are asymmetric bowtie with skewed axis (32.0%), asymmetric bowtie with inferior steepening (30.0%) and inferior steepening (19.0%). In mild keratoconus patients topography showed largely one pattern, inferior steepening (30.6% of mild keratoconus). In case of moderate keratoconus patients topography shows mainly three patterns, asymmetrical bowtie with skewed axis (19.0%), asymmetric bowtie with inferior steepening (16.5%) and inferior steepening (10.5%). In severe keratoconus patients topography shows mainly three patterns, asymmetrical bowtie with inferior steepening (10.5%), asymmetric bowtie with skewed axis (9.5%) and irregular pattern (8.5%). There was no round, superior steepening, symmetric bowtie or asymmetric bowtie with superior steepening pattern in severe keratoconus.&#x0D; Conclusion: The pattern of topography varies among the different stages of keratoconus patients. From the topography pattern we can diagnose the keratoconus early and also get the information of severity of the disease and treat accordingly.&#x0D; J. Natl. Inst. Ophthalmol. 2022; 5(2):31-36