Mean Keratometry Research Articles

Calculation of intraocular lens power after trabeculectomy

To assess biometric changes in eyes after trabeculectomy (TE) and its impact on refractive outcomes of phacoemulsification (PE) in order to determine the corrections for calculation of intraocular lens (IOL) power. The study included two groups of patients: the 1st group consisted of 116 patients who were assessed by optical biometry (IOL-Master 500) for mean biometric values before and after TE; the 2nd group included 31 patients with history of TE (study subgroup) and 47 individuals without glaucoma (control subgroup) who underwent PE with subsequent comparison of IOL calculation accuracy. There was significant axial length (AL) shortening in the 1st group from 23.28±0.97 to 23.19±0.97 mm (p<0.001) 6 months after TE, which positively correlated (r=0.296, p=0.001) with intraocular pressure (IOP) decrease (from 25.4±5.34 to 17.2±4.42 mm Hg, p<0.001). Mean keratometry and anterior chamber depth values did not significantly change after TE. Mean IOL power calculation error after PE in the 2nd group was -0.05±0.47 D and 0.003±0.62 D for the control and study subgroups, respectively (p=0.697). However, significant impact of preoperative IOP on IOL power calculation error was discovered in the study subgroup (R2=0.526, p<0.001), but not in the control subgroup (R2=0.061, p=0.052). Based on linear regression, the expected IOL power calculation errors depending on the preoperative IOP were determined for patients with history of TE. AL shortening due to decrease in IOP in patients with history of TE leads to IOL power calculation errors. Expected IOL calculation error related to preoperative IOP level was determined, which could help improve refractive outcomes of PE in patients with history of TE.

Comparison of ocular discomfort after three different epithelial debridement techniques for corneal collagen cross-linking in keratoconus treatment.

Purpose:To compare the severity and duration of ocular discomfort after three different epithelial debridement techniques for corneal collagen cross-linking in the treatment of keratoconus.Methods:Fifty-five patients (65 eyes) known to have keratoconus were enrolled in this retrospective study. The eyes were divided into three groups based on the technique used for epithelial debridement for corneal collagen cross-linking procedure; excimer laser transepithelial phototherapeutic keratectomy was used in group 1 (18 eyes), alcohol-assisted epithelial removal was used in group 2 (27 eyes), and mechanical epithelial debridement was used in group 3 (20 eyes). Preoperative and postoperative (third month) best-corrected visual acuity (BCVA) using Snellen chart, objective refraction, and keratometry results were recorded. The results of the questionnaire obtained from the patient’s medical records were reviewed regarding their subjective evaluation of postoperative symptoms including foreign body sensation, tearing, photophobia, and burning at the end of the first postoperative week. Paired-samples t test was used to compare preoperative and postoperative clinical findings. One-way analysis of variance (ANOVA) was used to analyze the differences between three independent groups.Results:BCVA improved from 0.51 ± 0.27 to 0.58 ± 0.21 (p = 0.05). Objective mean spherical and cylindrical refraction decreased from −5.08 ± 2.78D to −4.46 ± 2.91D (p = 0.22) and from −3.45 ± 2.73D to −3.03 ± 1.97D (p = 0.25). Mean maximum keratometry reading (Kmax) decreased from 57.63 ± 4.73D to 56.13 ± 4.47D (p = 0.001). The mean score for foreign body sensation was the highest in group 3 (4.50 ± 0.53) and the lowest in group 1 (2.10 ± 1.85) (p = 0.01). The mean scores for tearing, photophobia, and burning sensation were comparable in three groups (p = 0.84, p = 0.13, and p = 0.61, respectively). The duration of photophobia was the shortest in group 1 (1.50 ± 2.37 days), followed by group 3 (2.00 ± 1.31 days) and group 2 (4.00 ± 1.83 days) (p = 0.04).Conclusions:The severity and duration of adverse subjective symptoms during the first postoperative week after corneal collagen cross-linking appear to be milder with epithelial debridement using excimer laser transepithelial technique compared with -assisted debridement and mechanical debridement.

Correction methods for noncontact intraocular pressure measurement in patients with keratoconus and healthy individuals.

The objective of this study was to investigate the usefulness of four different algorithms to correct noncontact intraocular pressure measurement errors in keratoconus patients and normal individuals. Noncorrected intraocular pressure and corrected intraocular pressures were measured in one eye of 34 patients with keratoconus and 34 age- and gender-matched healthy controls using Corvis Scheimpflug Technology. The correlation of noncorrected intraocular pressure and corrected intraocular pressures with age, axial length, corneal shape, thickness, and biomechanics was calculated. Corrected intraocular pressures were compared with noncorrected intraocular pressure using paired t test and Bland-Altman plots (95% limits of agreement). The noncorrected intraocular pressure correlated with corneal thickness and biomechanical parameters in both groups (all p≤0.047), and front and back mean keratometry in the keratoconus group (r=-0.39, p=0.02, and r=0.39, p=0.02, respectively). After adjustment with different intraocular pressure correction algorithms, biomechanically corrected intraocular pressure showed a minimal correlation with corneal features and a nonsignificant difference with noncorrected intraocular pressure in the healthy group (-0.1 ± 1.1 mmHg, p=0.58; 95% limits of agreement: -2.3 to 2.1 mmHg). Measuring intraocular pressure using noncontact tonometry and its corrected forms with a corneal thickness-based simple linear formula in patients with keratoconus is associated with many errors. Using more complex formulas that take into consideration more corneal stiffness parameters in addition to corneal thickness, such as biomechanically corrected intraocular pressure formula, may be more reliable and beneficial in this group of patients.

Aberrometric and visual outcome of intracorneal ring segments with sequential epi-off accelerated cross-linking in keratoconus corneas: a long-term follow-up study

Purpose The aim of this study was to analyze the effectiveness, predictability, and aberrometric changes of implanted intracorneal ring segments (ICRSs) with sequential cross-linking (CXL) in keratoconus patients during a 24-month follow-up period. Patients and methods This is a prospective cohort study that was carried out on 21 eyes of 17 keratoconus patients. ICRS were implanted in these eyes during the period from 2013 to 2017. Mechanical dissection of the lamellar pockets was the technique used. This was followed by CXL 6 weeks later. Patients were followed up to assess refraction, topography, and aberrometry at 6, 12, and 24 months postoperatively. Aberrometry used coefficient settings in the NIDEK OPD-Scan for more sensitivity. The main outcome measures included uncorrected visual acuity, best-corrected visual acuity, refraction, keratometric values, total root mean square at the 3 mm zone, coma order (7), coma order (8), and trefoil order (6) of high-order aberrations. Results There was a statistically significant improvement in uncorrected visual acuity and best-corrected visual acuity, with a significant reduction in the refractive error and the mean keratometry values (P Conclusions ICRS, followed by CXL was an effective method for improving and stabilizing visual, keratometric, and aberrometric values in keratoconus.

Коррекция индуцированного астигматизма и сопутствующей миопии высокой степени методом имплантации кольца MyoRing с применением фемтосекундного лазера

Purpose. Analysis of the results of astigmatism correction after penetrating keratoplasty and concomitant high myopia using the MyoRing ring implantation, clinical case as an example. Material and methods. Patient G., 51 years old, underwent surgery to correct astigmatism and concomitant high myopia. MyoRing was implanted in the right eye within corneal transplant limits using femtosecond laser-assisted intrastromal MyoRing implantation. Before the surgery uncorrected visual acuity at the operated eye was 0.01; corrected visual acuity 0.06; spherical component of refraction was (–)6.0 D, cylindrical component was (–)8.0 D. Mean keratometry in the right eye was 43.96 D. Corneal hysteresis was 6.5 mm Hg, corneal resistance factor was 5.5 mm Hg, cornea thickness in center was 529 mkm. The patient was followed up for one year. Results. In 12 months after the surgery visual acuity of the right eye without correction was 0.7 and 0.8 with correction. Spherical component was (–)1.0 D, cylindrical component was (–)2.0 D. Mean keratometry in the right eye was 35.10 D. Corneal hysteresis was 7.2 mm Hg, corneal resistance factor was 6.3 mm Hg, cornea thickness in center was 533 mkm. The patient was satisfied with the result of operation. Conclusion. Femtosecond laser-assisted intrastromal MyoRing implantation for correction induced astigmatism after penetrating keratoplasty and concomitant high myopia is efficient, safe and provides strengthening of biomechanical properties of the cornea besides refractive and visual effect. Key words: postkeratoplastic astigmatism, high myopia, MyoRing, femtosecond laser

Refractive Outcomes of Cataract Surgery With or Without Endocyclophotocoagulation.

Surgeons that perform cataract surgery combined with endocyclophotocoagulation (ECP) should rely on their preferred intraocular lens (IOL) calculation formula. There is no need to perform any correction to the IOL power, as this procedure does not modify the refractive outcome. The purpose of this study was to compare postoperative refractive outcomes in patients with glaucoma who underwent phacoemulsification and IOL implantation with or without ECP and the change in intraocular pressure (IOP) and number of antiglaucoma medications between groups. A cross-sectional study in which the medical records of the patients with any type of glaucoma, who underwent phacoemulsification with IOL implantation in the capsular bag in addition to ECP or as a standalone procedure from June 2016 to August 2019 were analyzed. Clinical data collected included axial length, steep, flat, and mean keratometry values, target spherical equivalent (SE) estimated by the SRK/T formula, manifest refraction SE at the 1-month follow-up, IOP, and number of antiglaucoma medications before and 12 months after surgery. Primary and secondary outcome measures were the mean predictive error (MPE), the postoperative SE, and the change in IOP after surgery in both groups, respectively. Significance was assessed using the Student t test for all variables between groups according to data distribution. P-values <0.05 were considered to be statistically significant. A total of 196 eyes of 196 patients were included, 98 in the combined phacoemulsification-ECP group, and 98 in the non-ECP group. The observed MPE was -0.043±0.44, and 0.06±0.38 D MPE, respectively (P=0.079). Overall, 74.34% in the phacoemulsification-ECP group and 78.4% in the non-ECP group had a postoperative SE of ±0.50. The ECP group had lower IOP and a greater decrease in antiglaucoma medications at 12 months of follow-up. SRK/T formula performed well in both groups, with no statistically significant difference in the MPE and the percentage of eyes achieving postoperative SE of ±0.50. We consider it is unnecessary to perform any kind of correction to the IOL power calculation when performing ECP.

Treatment effect with 2 photorefractive intrastromal cross-linking protocols in low-grade myopia through 24-month follow-up.

To assess the effect of two high-oxygen epi-on PiXL treatments for low-grade myopia. This prospective, randomized, intra-individually comparing, single-masked study included 23 healthy volunteers (46 eyes) aged 18-35years with mild myopia, -0.75 to -2.50 D manifest refractive spherical equivalent (MRSE). One eye was randomized to a 4.0-mm homogenous treatment zone and the fellow eye to a 4.0-mm annular zone (16:40min at 30mW/cm2 , fluence 15J/cm2 ). Uncorrected distance visual acuity (UDVA), MRSE, best spectacle-corrected visual acuity (BSCVA), Scheimpflug light scattering depths, mean keratometry (Kmean ) and endothelial cell count (ECC) were assessed through 24months. Similar improvements in UDVA were seen for the homogeneous and annular protocols at 1month: -0.52 (-0.59, -0.39) and -0.49 (-0.59, -0.39) logMAR, respectively (medians and interquartile ranges, IQR), p=0.91, and MRSE: +1.0 D (0.94, 1.31) and +1.0 D (0.69, 1.25), p=0.17. Light scattering depths were 496 (465, 527) and 349 (247, 378) µm, respectively, and the reduction in mean keratometry was -0.8 D (-1.1, -0.7) and 0 D (-0.1, 0.1), p<0.001. The treatment effect remained stable throughout 24months. At 1week, the participants reported less ocular discomfort with the annular protocol. No reductions were seen in BSCVA or ECC. No adverse events were reported. PiXL can reduce low-grade myopia and improve uncorrected vision in healthy eyes. The initial ocular discomfort may be reduced with an annular treatment zone. Further studies are needed to optimize PiXL treatment parameters.

Risk factors and association with severity of keratoconus: the Australian study of Keratoconus.

Our results show that asthmatic patients tend to have more severe KC and thus close monitoring for disease progression would be advised, and appropriate treatment strategies may be actioned stabilise the condition that may reduce the need for future corneal transplantation. To explore a wide range of risk factors associated with the severity of keratoconus (KC). A cross-sectional study of KC patients was undertaken in Melbourne, Australia. A questionnaire addressing age, gender, educational background, ocular and medical history, smoking and alcohol consumption, and physical examination comprising anthropometric measurements was collected; eye examination was undertaken. The associations between a range of risk factors and the severity of KC were determined using univariate and multivariable linear regression analyses. A total of 260 KC subjects were included in this study. Mean age of subject was 35.5 (SD = 14.8) years and the majority of the subjects were European 171 (68.2%). Initial univariate regression analysis identified the following risk factors at the p < 0.1 level with KC: higher body mass index, smoking cigarettes, diabetes, rheumatoid arthritis and asthma were associated with increased severity of KC, whereas eczema was associated with less severe KC. Following multivariable regression analysis, only asthma remained as a significant risk factor associated with 2.2 diopters (D) steeper average mean keratometry compared to KC subjects having no asthma [p = 0.03; β = 2.18; 95% confidence intervals: 1.22, 4.14]. Our study describes the comprehensive assessment of all the known risk factors in a large KC cohort recruited in Australia. Our study has reported asthma as the only risk factor found to be significantly associated with the severity of KC. The results of this study allow us to better understand the aetiology of KC and such knowledge could be useful in instigate systemic management of patients to slow or prevent KC.

Biometry data and prevalence of corneal astigmatism in caucasian spanish candidates for cataract surgery

To describe ocular biometric parameters and the prevalence of corneal astigmatism as well as age and gender correlations in a population of cataract surgery candidates and to estimate the number of eyes that would be candidates for a toric intraocular lens (IOL). In consecutive patients requiring cataract surgery over a one-year period (June 2016 to June 2017), the following optical biometry measurements were performed on an IOLMaster 700 or Lenstar 900: axial length (AL), anterior chamber depth (ACD), lens thickness (LT), mean keratometry (K), flat keratometry (K1), steep keratometry (K2), corneal astigmatism (Cyl) and white-to-white diameter (WTW). Descriptive statistics for the demographic and biometric data were analyzed. The study sample included 6111eyes of 3332patients (59.3% women), with a mean age of 74.78±9.7years. The means of the compiled data are as follows: AL 23.58±1.55mm, ACD 3.08±0.41mm, LT 4.55±0.52mm,K 44.15±1.54 diopters (D), K1 43.64±1.57 D, K2 44.69±1.61 D, Cyl 1.0±0.81. D and WTW 11.88±0.46mm. The male patients had significantly larger eyes (higher AL, ACD and WTW) and flatter corneas (lower flat and steep K). Older patients had significantly lower AL, ACD and WTW, while their LT values were higher. Corneas became significantly steeper with age. 60.5% of eyes had less than 1 D of corneal astigmatism, while 3.1% had ≥3.0 D. Less than 1 D of corneal astigmatism was present in the majority of cataract surgery candidates. 3.1% of eyes were candidates for a toric IOL. This study provides useful information on inventory requirements for planning hospital resources.

A perspective of biometric, visual and refractive outcomes of cataract surgery: a report of an ophthalmologist in compulsory governmental service

Objectives: Knowledge of normal values of biometric parameters in cohort and relationships of them is helpful for ophthalmologists who want to achieve successful results. The aim of this study is to define these parameters in the light of experiences of an individual cataract surgeon after her residency program. Methods: This is a retrospective, register-based study. Preoperative biometric and postoperative refractive data including axial length (AL), mean keratometry (K), anterior chamber depth (ACD), astigmatism, lens thickness (LT) of 310 patients who had cataract surgery were reviewed. Ultrasound and optical biometry were used to evaluate the biometric parameters of the eyes. Results: 0.5 D of refractive target (RT) was obtained in 52.1% (186 eyes) of eyes, 1.0 D of RT in 82.20% (293 eyes) and 2.0 D of RT in 98.3% (351 eyes). Analyses of visual acuity show that 43.7% and 86.3% of eyes reached 0.00 and 0.30 log MAR or better. Age, ACD, LT, AL, preoperative corrected distance visual acuity, preoperative astigmatism and preoperative K were correlated between each other significantly (p &amp;lt; 0.001). The longer AL was found associated with older age (β = .745, p = 0.003), and lower K (β = -0.327, p &amp;lt; 0.001). A significant association between K value and older age (β = .680, p = .029) and shorter AL (β = -.660, p &amp;lt; 0.001) was seen. Conclusions: These data show the normative parameters of biometry values for the Turkish population. These results may be helpful in calculating intraocular lens power and evaluating refractive error for young ophthalmologists who have to work with ultrasound biometry in compulsory service.

Differential diagnosis of Marfan syndrome based on ocular biologic parameters.

BackgroundThe present study aimed to investigate the ocular characteristics of Chinese patients with Marfan syndrome (MFS) and to evaluate the sensitivity and specificity of ocular parameters in distinguishing MFS from ectopia lentis.MethodsA total of 103 patients (103 eyes) with ectopia lentis from 13 provinces and 47 cities were recruited from Zhongshan Ophthalmic Center, Sun Yat-sen University, from June 2017 to June 2019. Ghent-2 criteria were used, as they are the gold standard diagnostic criteria for MFS. Ocular parameters, such as flat keratometry (Kf), steep keratometry (Ks), mean keratometry (Km), corneal astigmatism (AST), axial length (AL), white-to-white corneal diameter (WTW), central corneal thickness (CCT), and axial length/curvature radius (AL/CR), were recorded. Diagnostic analyses based on various combinations of parameters to differentiate MFS from ectopia lentis were made using receiver-operating characteristic (ROC) curves.ResultsThe mean age of the 103 included patients was 10.25±9.67 (range: 3–48) years, and 66.02% were male. Km combined with CCT was found to have good sensitivity and specificity in the differential diagnosis of MFS from ectopia lentis; Km of 41.36 D and CCT of 537.32 mm were found to be the optimal cut-off points, representing a sensitivity of 89.8% and specificity of 68.7%.ConclusionsSpecial characteristics of ocular parameters were detected in MFS. Our findings indicate that ocular biologic parameters are valuable for the differential diagnosis of MFS from ectopia lentis. Km, combined with CCT, could be used as a screening tool for MFS.

MyoRing Implantation with and without Corneal Collagen Crosslinking for the Management of Keratoconus

Purpose To evaluate the safety and efficacy of femtosecond laser-assisted MyoRing implantation with concurrent corneal collagen crosslinking (CXL) compared to MyoRing alone for the treatment of progressive keratoconus.MethodsA total of 60 patients were enrolled in this randomized controlled trial. The patients were randomly allocated into two groups. In the first group, MyoRing was implanted, while in the second, it was inserted in the corneal stroma using the same technique, along with simultaneous CXL. Visual, refractive, topographic, and abberometric outcomes were measured preoperatively and at every postoperative visit.ResultsData of 47 patients were available at the end of the study; 28 in the MyoRing group and 19 in the MyoRing + CXL group. The mean uncorrected distance visual acuity (UDVA) improved from 0.79 0.39 logMAR to 0.52 0.31 logMAR (P 0.05) in the MyoRing + CXL group and from 0.65 0.38 logMAR to 0.62 0.23 logMAR (P = 0.70) in the MyoRing group. CDVA changed from 0.33 0.19 logMAR to 0.25 0.16 logMAR (P = 0.10) in the MyoRing + CXL group and 0.32 0.22 logMAR to 0.33 0.17 logMAR (P 0.50) in the MyoRing group. The mean keratometry (Km) decreased from 47.5 2.7 D to 43.8 3.2 D (P 0.001) in the MyoRing group and 49.3 3.4 D to 45.1 3.0 D (P 0.001) in the MyoRing + CXL group. Besides, horizontal coma was significantly lower in the MyoRing + CXL group (P = 0.022).ConclusionMyoRing insertion combined with CXL is a safe and effective method for the treatment of keratoconus. The visual and topographic outcomes were comparable to that for MyoRing insertion after 10 months; however, horizontal coma was significantly lower in the MyoRing + CXL group.

Long-term refractive outcomes in patients with cataracts and keratoconus after phacoemulsification with toric intraocular lens implant.

To determine the refractive stability of patients with keratoconus and cataracts after the implantation of a toric intraocular lens. This is a cross-sectional, retrospectivestudy. Clinical records from patients with non-progressive keratoconus and cataracts that underwent non-complicated phacoemulsification with toric IOL implantation were reviewed. Mean keratometry (Km), refractive cylinder (RC), spherical equivalent (SE), steeper keratometry (K), and axis were evaluated at the 1-month, 6-month, 12-month, and 24-month follow-up visits. Fifty-four eyes from 41 patients were included. Thirty-seven (68.5%) female and 17 (31.5%) male patients, with a mean age of 67.52 ± 8.22. Refractive cylinder at postoperative 30 days was -1.61 ± 1.23, 6-month -1.22 ± 0.80, 12-month -1.10 ± 0.83 and 24-month visit after surgery was -1.37 ± 0.77(p = 0.290). SE at the 30-day visit was -0.82 ± 1.90, 6-month -0.64 ± 1.23, 12-month -0.78 ± 1.91 and at 24-month postoperative visit -1.02 ± 1.87 (p = 0.210). Km value at the 1-month visit was 47.23 ± 1.95, 6-month 47.87 ± 1.61, 12-month 46.39 ± 2.52 and 24-month postoperative visit 46.92 ± 1.26 (p = 0.877). The steeper K axis in the 30-day control was 78.53 ± 30.12, 6-month 77.29± 37.68, 1-year 93.13 ± 62.42, 24-month 67.31 ± 38.49 (p = 0.632). Our findings suggest a low variation in the refractive outcome for patients with mild and moderate keratoconus and cataracts, without evident progression signals, a demonstrated keratoconus clinical stability. No statistically significant postoperative changes in the refractive cylinder, SE, mean K, and steeper K axis were observed, which suggests good predictability for toric IOL implant.

Impact of Eye Drops Instillation of Antihypertensive Drugs on the Refractive Power of the Cornea

Purpose: to assess effect of eye drops instillation on the refractive power of the cornea and potential intraocular lens (IOL) power calculation errors appearing related within.Patients and methods. There were 478 patients divided in 3 groups: 1st — patients without glaucoma and topical treatment (n = 325); 2nd — individuals with primary open angle glaucoma (POAG) on treatment (n = 122); 3rd — patients with POAG and previous trabeculectomy (TE) without using eye drops (n = 31). For each patient keratometry was performed by IOL-Master 500. Mean preoperative keratometry and corneal astigmatism were compared within IOL calculation error received by Barrett Universal II formula 1 month after phacoemulsification (PE).Results. Mean keratometry was significantly (p &lt; 0.001) less (0.6 D) at the 1st group (44.00 ± 1.96 D) versus 2nd group (44.6 ± 1.76 D). Cancellation of topical eye drops due to TE leads to insignificant decline of corneal curvature (from 44.6 ± 1.76 D to 44.1 ± 1.59 D). There was no any difference in corneal astigmatism level between study groups (0.92 ± 2.23 D, 0.8 ± 0.59 D and 0.86 ± 0.50 D for groups respectively) as like as no distinction in IOL calculation error in these groups (–0.08 ± 0.57 D, –0.06 ± 0.6 D and 0.003 ± 0.61 D). However, men have more flatter cornea (43.6 ± 1.98 D) than women (44.4 ± 1.80 D) (p &lt; 0.001). Mean keratometry at the age group 60–74 years was less (43.7 ± 2.3 D) than at 75–90 years (44.4 ± 1.54) (p = 0.002).Conclusion. Patients with coexistent cataract and glaucoma on treatment require special attention in IOL calculation. To avoid keratometric errors it is recommended to prescribe lubricants and change hypotensive eye drops to preservative-free analogs to form a stable tear film.

Topographic screening reveals keratoconus to be extremely common in Down syndrome.

Keratoconus disproportionately affects people with Down syndrome (DS). This is the first study of its kind in Australasia. To investigate the prevalence of keratoconus in DS. Cross-sectional study. Athletes with DS attending 2017 New Zealand Special Olympics National Summer Games. Keratoconus was identified using corneal topography (TMS-4N, Tomey). Topography from both eyes was required to be included. Two independent quantitative criteria were used to indicate keratoconus. The first was keratoconus severity index ≥ 30%. The second, adapted from the literature, required at least four of eight topographic parameters to be abnormal. Data from the worse eye were analysed. Diagnosis in each group was subsequently confirmed qualitatively by three corneal fellowship-trained ophthalmologists. Those with a definitive diagnosis were grouped into Keratoconus Confirmed Group 1 (KCC1) and Keratoconus Confirmed Group 2 (KCC2), respectively. Keratoconus prevalence, severity, demographics. Of 110 athletes screened, N = 98 were included, mean age 30.0 ± 9.7 years. Using only topographic data, keratoconus was identified in 39 (39.8%) athletes by quantitative topographic criteria 1, and in 63 (64.3%) athletes by criteria 2. Keratoconus was confirmed by qualitative sub-specialist review in 30 (30.6%) (KCC1) and 38 (38.8%) (KCC2) athletes, respectively. Mean keratometry in groups KCC1 and KCC2 were 48.4 ± 3.2D and 48.2 ± 2.9D, respectively. Most were male (KCC1 63.3%, KCC2 76.3%) and of European ethnicity (KCC1 80%, KCC2 78.9%). We report keratoconus in 30.6% to 38.8% of athletes with DS; therefore, we believe keratoconus screening is indicated in DS for early management.

Analysis of visual, refractive, topographic and aberrometric changes in different uncommon accelerated cross-linking protocols in keratoconus: A 12 month follow-up

To describe the visual, refractive, topographic and aberrometric outcomes of six different accelerated cross-linking (ACXL) protocols in progressive keratoconus (KC) at 12 months. This observational retrospective study included 62 eyes of 49 patients with progressive KC that received one of the following accelerated cross-linking protocols: Group I (8 patients, 5.4 J/cm 2, 15mWx12min, pulsed), Group II (11 patients, 5.4 J/cm 2 , 6mWx15min, continuous), Group III (16 patients, 5.4 J/cm 2 , 9mWx10min, continuous), Group IV (13 patients, 5.4 J/cm 2 , 30mWx6min, pulsed), Group V (8 patients, 7.2 J/cm 2 , 15mWx16min, pulsed) and Group VI (6 patients, 7.2 J/cm 2 , 30mWx8min, pulsed). Best corrected visual acuity (BCVA), sphere, refractive cylinder, spherical equivalent (SE), maximum keratometry (Kmax), mean keratometry (Km), flat keratometry (K1), steep keratometry (K2), thinnest pachymetry, total aberrations, high order aberrations (RMS-HOA), spherical aberration, coma and trefoil were studied previously and at 12 months. Intragroup and intergroup statistical analysis was performed. Postoperative complications were noted. 11 patients were females(22,45%) and 38 males(77,55%). Improvement in the BCVA was observed in all groups (P > 0.05). Kmax reduced in all patients and was statistically significant in groups II (p = 0.041), III (p = 0.017), IV (p = 0.018) and V (p = 0.018). Flattening of the Km was significant in groups II (p = 0.028), IV (p = 0.008) and V (p = 0.028), as well as the K1 in groups IV(p = 0.01) and V(p = 0.028) and K2 in group IV(p = 0.036). There was no significant difference in the thinnest pachymetry in any of the groups. Total aberrations, RMS-HOA, spherical aberration and coma reduced in all groups with statistical significance in Group V (P = 0.016). Two patients in Group I had anterior stromal scarring and one patient in Group V presented an unexpected overflattening. Progression was noticed in one patient in Group II. Accelerated CXL protocols included in this study can be considered effective and safe procedures in stopping the progression of keratoconus at 12 months. Improvement in BCVA and wavefront analysis is observed, but results are limited by the number of patients. Caution should be taken when applying high radiance and long duration protocols to prevent undesirable events.

Accelerated contact lens–assisted corneal crosslinking and piggyback modification in a pediatric case with advanced keratoconus and thin cornea

A 14-year-old girl presented with bilateral keratoconus (KC). Maximum keratometry was 63.9 diopters (D) in the right eye and 63.7 D in the left eye. Minimum corneal thickness was 371 μm in the right eye and 370 μm in the left eye. The right eye underwent epithelium-off accelerated corneal crosslinking (CXL) using hypotonic dextran-free 0.1% riboflavin solution and a riboflavin-soaked ultraviolet-barrier-free soft contact lens to increase thickness to more than 400 μm. The same procedure was followed for the left eye 4 months later, when 2 riboflavin-soaked soft contact lenses were applied in piggyback fashion. At 19 months postopertively, in the right eye, visual acuity, maximum keratometry, mean keratometry, and topographical indices were improved. In the left eye, visual acuity, mean keratometry, and central KC index were improved. Accelerated CXL and piggyback modification was a safe and an effective treatment in this pediatric case with KC with thin cornea.

Effect of photorefractive keratectomy on agreement of anterior segment variables obtained by a swept-source biometer vs a Scheimpflug-based tomographer.

To evaluate agreement of anterior segment variables between Pentacam-AXL and IOLMaster 700 before vs after photorefractive keratectomy (PRK). Salouti Eye Clinic, Shiraz, Iran. Prospective cohort with interdevice agreement analysis. This study included healthy PRK candidates who were assessed with both devices preoperatively and 6 months after PRK. Only data from the right eye of each patient was analyzed. Pentacam-AXL average keratometry (AvgK) and zonal keratometry in the central 2.5 mm zone (zonal-K2.5) were each compared with mean keratometry (Km) from the IOLMaster 700. Other main outcome measures included vector analysis of corneal astigmatism (J0 and J45), central corneal thickness (CCT), anterior chamber depth (ACD), and white-to-white (WTW) distance. Axial length (AL) measurements by the same devices on a new cohort of 40 patients who had undergone PRK were also assessed. A paired t test was used to assess the interdevice measurement differences, and Bland-Altman analysis was used to calculate the 95% limits of agreement (LoA). This study included 97 patients. Preoperative vs post-PRK 95% LoAs between Pentacam-AXL and IOLMaster 700 were as follows: AvgK/Km (-0.42, 0.08 diopter [D]) vs (-0.49, 0.18 D); zonal-K2.5/Km (-0.40, 0.32 D) vs (-0.57, 0.74 D); J0 (-0.33, 0.18 D) vs (-0.28, 0.35 D); J45 (-0.28, 0.23 D) vs (-0.24, 0.27 D); pupil pachymetry/CCT (-18, 12 μm) vs (-2.6, 19.6 μm); apical pachymetry/CCT (-17.4, 12.8 μm) vs (-1.7, 20.9 μm); ACD (-0.03, 0.13 mm) vs (-0.03, 0.13 mm); WTW (-0.68, 0.23 mm) vs (-0.63, 0.14 mm); and AL (-0.07, 0.01 mm) vs (-0.07, 0.03 mm), respectively. PRK showed a negative impact on interdevice agreement for CCT and corneal power measurements, whereas it did not have a significant effect on the agreement of devices for ACD, WTW, AL, and the J45 astigmatism vectoral component. For IOL power measurement in post-PRK eyes, the 2 devices could be regarded as interchangeable for measuring AL and ACD but not for keratometry readings.

The impact of hybrid contact lenses on keratoconus progression after accelerated transepithelial corneal cross-linking.

To investigate the effect of hybrid contact lenses (HCLs) on keratoconus (KCN) progression after accelerated transepithelial cross-linking (A-TE CXL). Thirty-five eyes of 26 patients who preferred Ultrahealth HCLs for an optical correction after A-TE CXL formed the study group, and 45 eyes of 34 patients who preferred spectacle correction were age- and sex-matched to form the control group. Corrected distance visual acuity (CDVA), maximum keratometry, mean keratometry, apical posterior keratometry, cylindrical power, minimum corneal thickness, keratoconus vertex indices and curvature asymmetry indices obtained by Scheimpflug corneal topography were compared before, 6 and 12months after the procedure. Anterior segment optic coherence tomography (AS-OCT) was performed to measure the apical corneal clearance of HCL-wearing patients. The median pre-CXL CDVA value of the patients in the HCL group was logMAR 0.30 (0.20-1.0), and it was logMAR 0.30 (0.10-1.0) in the spectacle-corrected group. There was a significant increase in CDVA 6 and 12months after CXL procedure in both groups (p < 0.001, 0.003, respectively). The median front curve asymmetry index (FCAsym) significantly improved after A-TE CXL in the HCL group. The pre-CXL and 12th-month topographic comparisons of the spectacle-corrected group revealed no significant difference. In addition, no significant difference was observed between topographic alterations of two groups (p > 0.05). The CDVA significantly improved, and KCN progression was halted in patients wearing HCL 12months after A-TE CXL. Besides, FCAsym indices can be considered for follow-up of the HCL-wearing patients as an assistive parameter to AS-OCT measurements.

Prevalence of Keratoconus Based on Scheimpflug Imaging: The Raine Study

To describe the prevalence and systemic associations of keratoconus in young adults in Perth, Western Australia. Cross-sectional study. One thousand two hundred fifty-nine participants 20 years of age. The Raine Study is a multigenerational, longitudinal cohort study based in Perth, Western Australia. This study represents a cross-sectional analysis of the birth cohort on returning for a 20-year follow-up. Participants underwent a detailed ophthalmic examination, including visual acuity assessment and Scheimpflug imaging using the Pentacam (Oculus, Wetzlar, Germany), and completed a health questionnaire. Keratoconus was defined as a Belin/Ambrόsio enhanced ectasia display score of 2.6 or more in either eye based on Pentacam imaging. Prevalence of keratoconus in this cohort. Of the 1259 participants, 50.8% were women and 85.7% were White. Fifteen participants had keratoconus in at least 1 eye, giving a prevalence of 1.2% (95% confidence interval, 0.7%-1.9%), or 1 in 84. A significant difference was found in best-corrected visual acuity (0.01 logarithm of the minimum angle of resolution vs. -0.05 logarithm of the minimum angle of resolution; P= 0.007), cylinder (1.25 diopters [D] vs. 0.25 D cylinder; P < 0.001) and spherical equivalent (-1.42 D vs. -0.50 D sphere; P= 0.02) on objective refraction, mean keratometry of the steep meridian (45.19 D vs. 43.76 D; P < 0.001), and mean corneal thickness at the thinnest point (475 μm vs. 536 μm; P < 0.001) between those with and without keratoconus. Keratoconus was associated with regular cigarette smoking (38.5% vs. 14.6%; P= 0.04), but showed no association with gender, race, body mass index, use of spectacles or contact lenses, history of allergic eye disease, or pregnancy. The prevalence of keratoconus in this Australian population-based study of 20-year-old adults was 1.2% (95% confidence interval, 0.7%-1.9%), or 1 in 84, which is one of the highest reported in the world. This has important implications for screening individuals at a younger age so that treatment can be initiated before disease progression.