Diagnostic Accuracy of Corneal and Epithelial Thickness Map Parameters to Detect Keratoconus and Suspect Keratoconus.

Aim: To establish the diagnostic accuracy of corneal and epithelial thickness measurements obtained by spectral-domain optical coherence tomography (SD-OCT) in detecting keratoconus (KC) and suspect keratoconus (SKC). Methods: This retrospective study reviewed the data of 144 eyes separated into three groups by the Sirius automated corneal classification software: normal (N) (n = 65), SKC (n = 43), and KC (n = 36). Corneal thickness (CT) and epithelial thickness (ET) in the central (0-2 mm) and paracentral (2-5 mm) zones were obtained with the Cirrus high-definition OCT. Areas under the curve (AUC) of receiver operator characteristic (ROC) curves were compared across groups to estimate their discrimination capacity. Results: ROC curve analysis revealed excellent predictive ability for ET variables: minimum (Min) ET (0_2), minimum-maximum (Min-Max) ET (0_2), superonasal-inferotemporal (SN-IT) ET (2_5), Min-Max ET (2_5), and Min ET (2_5) to detect keratoconus (AUC > 0.9, all). Min-Max CT (0_2) was the only CT parameter with excellent ability to discriminate between KC and N eyes (AUC = 0.94; cutoff = ≤-32 µm). However, both ET and CT variables were not strong enough (AUC < 0.8, all) to differentiate between SKC and N eyes, with the highest diagnostic power for Min-Max ET (2_5) (AUC = 0.71; cutoff = ≤-9 µm) and central corneal thickness (CCT) (AUC = 0.76; cutoff = ≤533 µm). Conclusion: These results demonstrate that OCT-derived CT and ET are able to differentiate between KC and N eyes, with a high level of certainty. However, Min-Max ET (2_5) was the parameter with the highest ability to detect suspect keratoconus.

Corneal higher order aberrations by Sirius topography and their relation to different refractive errors.

PURPOSE: To compare the root mean square (RMS) of anterior corneal higher-order aberrations (HOAs) in ametropic and emmetropic eyes. METHODS: This retrospective observational study was conducted at the Department of Ophthalmology, Tishreen University Hospital, Latakia, Syria. Study eyes were divided into four groups based on refractive error: mild-to-moderate myopia, hypermetropia, myopic astigmatism, and emmetropic eyes as controls. The following anterior corneal HOAs were evaluated using the Scheimpflug-Placido Sirius (CSO, Italy) tomographer over 6 mm pupil: Root mean square (RMS) total corneal HOAs, RMS trefoil, RMS coma and RMS spherical aberrations. RESULTS: RMS values of total HOAs, trefoil and coma showed statistically significant differences in all four groups (P < 0.05, all). HOAs were noted to be lowest in the control group (0.18 ± 0.09, 011 ± 0.08 and 0.09 ± 0.08 µm, respectively) and highest in the myopic astigmatism group (0.31 ± 0.16, 0.15 ± 0.12, 0.17 ± 0.14 µm, respectively). RMS spherical aberration was lowest in the astigmatism group (0.00 ± 0.16 µm) with a statistically significant difference from that in the control group (0.05 ± 0.07 µm, P = 0.049). CONCLUSION: The mean RMS values of total HOAs, trefoil and coma were highest in the astigmatism group and lowest in the control group. However, spherical aberration was minimal in the astigmatism group. A better understanding and targeted treatment of higher-order aberrations in ametropic human eyes, and in particular eyes with astigmatism, may enhance visual quality and performance in the treatment of refractive errors. Recognising atypical HOAs may also assist in the early detection of pathological conditions such as keratoconus.

Evaluation of Anterior and Posterior Corneal Higher Order Aberrations for the Detection of Keratoconus and Suspect Keratoconus.

AIM: To investigate the application of anterior and posterior corneal higher-order aberrations (HOAs) in detecting keratoconus (KC) and suspect keratoconus (SKC). METHOD: A retrospective, case-control study evaluating non-ectatic (normal) eyes, SKC eyes, and KC eyes. The Sirius Scheimpfug (CSO, Italy) analyses was used to measure HOAs of the anterior and posterior corneal surfaces. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated. RESULTS: Two-hundred and twenty eyes were included in the analysis (normal n = 108, SKC n = 42, KC n = 70). Receiver operating characteristic (ROC) curve analysis revealed a high predictive ability for anterior corneal HOAs parameters: the root mean square (RMS) total corneal HOAs, RMS trefoil, and RMS coma to detect keratoconus (AUC > 0.9 for all). RMS Coma (3, ±1) derived from the anterior corneal surface was the parameter with the highest ability to discriminate between suspect keratoconus and normal eyes (AUC = 0.922; cut-off > 0.2). All posterior corneal HOAs parameters were unsatisfactory in discriminating between SKC and normal eyes (AUC < 0.8 for all). However, their ability to detect KC was excellent with AUC of >0.9 for all except RMS spherical aberrations (AUC = 0.846). CONCLUSIONS: Anterior and posterior corneal higher-order aberrations can differentiate between keratoconus and normal eyes, with a high level of certainty. In suspect keratoconus disease, however, only anterior corneal HOAs, and in particular coma-like aberrations, are of value. Corneal aberrometry may be of value in screening for keratoconus in populations with a high prevalence of the disease.

Prevalence of Keratoconus in a Population-Based Study in Syria.

Aim: To determine the prevalence and associations of keratoconus (KC) in a university student population in Syria. Methods: A prospective multicentre cross-sectional cohort study was conducted at two universities in Syria. Student volunteers were recruited from Tishreen University (Latakia governorate) and Damascus University (Damascus governorate). All participants underwent a comprehensive ocular examination. Placido/Scheimpflug-based corneal imaging using the Sirius (CSO, Florence. Italy), and a questionnaire to evaluate the baseline characteristics and medical history, as well as to highlight possible risk factors of KC. Univariate and bivariate analyses were performed. Results: The estimated prevalence of KC among all subjects was 1.43% (n = 12). A strong association between eye rubbing and keratoconus was found (OR 9.33, 95% CI 2.94-29.63, P < 0.001). Damascus University participants had a higher prevalence of KC than Tishreen University. However, the difference was not statistically significant. Conclusion: The prevalence of keratoconus in this Syrian student population was 1.43%. The results of this study demonstrate a high prevalence of keratoconus in the study population. Early detection of keratoconus through screening may yield benefits in preventing devastating sequelae of KC in populations with a high prevalence.

Corneal higher-order aberration changes after accelerated cross-linking for keratoconus.

AIM: To evaluate changes in corneal higher-order aberrations (HOAs) following epithelium-off accelerated corneal cross-linking (A-CXL) and to explore the impact on visual acuity. METHODS: In this retrospective case series, 32 eyes of 24 patients with keratoconus (KC) underwent A-CXL. Treatment was delivered at 10 mW/cm2 for 9 min with a total dose of 5.4 J/cm2. The following anterior corneal HOAs: total corneal HOAs, trefoil, secondary trefoil, coma, secondary coma, secondary astigmatism and spherical aberrations were analysed using the Scheimpflug-Placido Sirius (CSO, Italy) corneal topographer at baseline and 12 months following treatment. Multivariate analysis was used to evaluate the independent effect of HOA subtypes on changes in uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA). RESULTS: At one year post CXL, UDVA and CDVA were significantly improved, -0.13 ± 0.19 LogMAR (P = 0.0005) and -0.08 ± .0.11 LogMAR (P = 0.0003), respectively. The mean preoperative trefoil, secondary trefoil, secondary coma and secondary astigmatism were 0.95 ± 0.46; µm, 0.20 ± 0.11; µm, 0.29 ± 0.19; µm and 0.42 ± 0.17 µm, respectively. At one year, the mean values decreased significantly to 0.77 ± 0.47 µm, 0.15 ± 0.11 µm, 0.25 ± 0.18 µm and 0.34 ± 0.18 µm, respectively (P < 0.05, for all). No independent relationship between any HOA changes and change in UDVA was observed. A reduction in secondary coma aberration was associated with a change in CDVA (95% CI 0.01-1.34, P = 0.048; ß = 0.67). CONCLUSION: A 9-min protocol of Accelerated corneal cross-linking is an effective treatment in improving corneal HOAs at 12 months follow up, in eyes with progressive keratoconus at one year follow-up. A change in secondary coma had a statistically significant and independent effect on CDVA.

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

AIM: To evaluate the long-term outcomes of corneal cross-linking (CXL) in patients with progressive keratoconus. METHOD: 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. RESULTS: 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. CONCLUSION: 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.

Prevalence of Keratoconus and Keratoconus Suspect among Patients Seeking Refractive Surgery in Syria.

PURPOSE: The purpose of this study was to determine the prevalence of keratoconus (KC) and keratoconus suspect (KCS) among patients seeking refractive surgery in Syria. METHODS: This is a retrospective multicenter screening study. The study was conducted in Damascus University, Tishreen University, and Tartous Specialist Eye Center (a private center). Data were collected from refractive surgery candidates referred for preoperative evaluation before laser in situ keratomileusis, photorefractive keratectomy, intrastromal corneal rings, and phakic intraocular lens implantation. Corneal parameters were obtained by Scheimpflug-Placido tomography, Sirius (CSO, Italy). RESULTS: A total of 1479 patients were included in this analysis. The prevalence rates of KC and KCS were 18.19% (269/1479) and 13.52% (200/1479), respectively. In addition, patients with KC were found to have higher percentages of eye rubbing and astigmatism than suspect and normal (P < 0.0001). CONCLUSION: High prevalence rate of KC was found among patients seeking refractive surgery in Syria. Although this study was carried out on a highly selective population, it may reflect a high prevalence rate in a general population in Syria.

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.

Sensitivity and specificity of Sirius indices in diagnosis of keratoconus and suspect keratoconus.

AIM: To estimate the sensitivity and specificity of topographic and tomographic corneal parameters as determined by Sirius (CSO, Florence, Italy) in discriminating keratoconus (KC) and suspect keratoconus from normal cornea. METHOD: In this retrospective case-series study, keratoconus screening indices were measured using Sirius tomographer. Receiver operating characteristics (ROC) curves were used to determine the test's overall predictive accuracy (area under the curve) and to identify optimal cut-off points to maximize sensitivity and specificity in differentiating keratoconus and suspect keratoconus from normal corneas. RESULTS: Receiver operating characteristics (ROC) curve analyses showed high predictive accuracy for Symmetry Index back (SIb), Keratoconus Vertex front (KVf), Symmetry Index front (SIf), Keratoconus Vertex back (KVb), Apex Keratometry (Curve-Apex) and Minimum corneal Thickness (ThkMin) to distinguish keratoconus from normal (area under the curve > 0.9, all). Symmetry Index back was identified as the best diagnostic parameter for detecting suspect keratoconus with AUC of 0.86. Highest specificity to detect keratoconus and suspect keratoconus was seen for SIb, 99.87% and 84.66%, respectively. These values were associated with optimal cut-off points of 0.46 D for keratoconus and 0.12 D for suspect keratoconus. CONCLUSION: Sirius parameters evaluated in the study were effective to differentiate keratoconus from normal corneas. However, Symmetry Index back was the index with the highest ability to detect suspect keratoconus.

Iritis, glaucoma and corneal decompensation associated with BrightOcular cosmetic iris implant.

PURPOSE: NewColorIris cosmetic iris implants have a record of high ocular morbidity and are no longer in use. Newer generation of iris implants, BrightOcular, have patented posterior grooves in order to decrease iris touch and facilitate aqueous flow around the implant. However, little is known about their safety despite their implantations in 10 countries. METHODS: Collaborative case series of patients who had bilateral implantation of cosmetic iris implants solely for cosmetic reasons. RESULTS: 12 cases were collected being distributed as Caucasian (10) and Asian (2), women (11) and man (1) and with a mean age of 32 years. Ocular manifestations were present in 11 subjects and included anterior uveitis (10 of 12; 83.3%), glaucoma (7 of 12; 58.3%) and corneal decompensation (6 of 12; 50%). Visual acuity was normal in seven, decreased in five with two having visual recovery following explantation of the implant. Glaucoma could not be controlled medically in two patients. CONCLUSIONS: Cosmetic iris implants carry the risk of ocular damage when implanted in the anterior chamber of normal phakic eyes.

Cataractogenesis after Repeat Laser in situ Keratomileusis.

There has been the unsubstantiated clinical impression that laser refractive surgery accelerates cataract development along with solid experimental data about the cataractogenic effects of excimer laser treatment. We present the first documented case of significant cataract formation in a young myope after repeat excimer laser ablation necessitating phacoemulsification with a posterior chamber implant. Proposed explanations include focusing of the ablation wave on the posterior capsule (acoustic wave lens epithelial damage), photooxidative stress of the lens (ultraviolet and inflammatory oxidative stress), and corticosteroid-induced cataract (lens toxicity).