The Repeatability and Agreement of Ocular Parameters Measured with the MYAH and Myopia Master Devices between Expert and Non-Expert Practitioners.

In myopia control, it is essential to measure the axial length (AL) and corneal parameters, and to monitor whether changes in these parameters have occurred over time. The aim of this study was to analyse the repeatability and agreement between expert and non-expert practitioners in ocular parameters measured by the MYAH and Myopia Master. Three repeated measurements (n = 42) were recorded with the MYAH and Myopia Master by two (an expert and a non-expert) observers in a randomized order. The AL, K1, K2, and white-to-white (WTW) distance were collected. The intraobserver repeatability was excellent in all parameters measured with both devices in both observers. The AL outcome presented the best repeatability with the MYAH and Myopia Master (intraclass correlation coefficient, ICC = 1.0; coefficient of variation, CV ≤ 0.06% for both observers), while the WTW presented poorer results (ICC ≤ 0.991; CV ≤ 0.52%). The Myopia Master provides a significantly (p ≤ 0.01) flatter K1 and K2 as well as a lower WTW (p ≤ 0.01) than the MYAH. No statistically significant difference in AL measurements was found with either device (p ≥ 0.10; ICC = 1.0). None of the parameters showed differences (p ≥ 0.12) between the expert and non-expert observer. The MYAH and Myopia Master provide consistent measurements in a healthy adult population regardless of the previous clinical experience of the observer. AL measurements should be used interchangeably but K1, K2, and WTW should be used interchangeably with caution.

Influence of Keratoconus Severity on Detecting True Progression with Scheimpflug Imaging and Anterior Segment Optical Coherence Tomography.

To determine consistent change over time in keratoconus disease, it is necessary to establish progression cut-off values based on intersession variability of the device used to monitor the cornea. The aim of this study was to analyze the accuracy of corneal parameters using Scheimpflug tomography and anterior segment optical coherence tomography in healthy and keratoconic eyes of varying severity to determine the cut-off values that indicate real progression. Three repeated measurements of each cornea of healthy (20 eyes) and keratoconic eyes (mild = 16, moderate = 25 and severe = 20) were recorded using Pentacam and Casia SS-1000 devices, which were repeated 2-3 weeks later. K1, K2, maximal anterior and posterior keratometry, and corneal thickness at the thinnest location (TCT) were collected. The accuracy was excellent with both devices; however, the Casia device presented better repeatability and reproducibility in all parameters in all groups compared to the Pentacam. The cut-off of the Pentacam and Casia in the mild stage were lower (K1 = 0.50 and 0.37 D; K2 = 0.51 and 0.37 D; Kmax-A = 1.24 and 0.65 D; Kmax-P = 0.38 and 0.17 D; TCT = 19.64 and 11.19 µm) than that of the severe stage (K1 = 1.09 and 0.88 D; K2 = 1.41 and 0.87 D; Kmax-A = 2.74 and 2.15 D; Kmax-P = 0.82 and 0.22 D; TCT = 28.68 and 14.83 µm). These results show that the greater the keratoconus severity, the greater the change that must occur for it to be considered real.

Detecting True Change in Keratoconus after Intracorneal Ring Segment Implantation.

Confirming the progression of keratoconus is of paramount relevance to providing the appropriate treatment. Real change should be considered consistent over time. It must be greater than the variability of the measurement of the device used to monitor the cornea. The present study aimed to assess the intraobserver repeatability and intersession reproducibility of a Scheimpflug camera in measuring corneal parameters in virgin keratoconus and intrastromal corneal ring segments (ICRS) implantation eyes to discriminate real change from measurement noise. Sixty keratoconus and 30 ICRS eyes were included. Corneal parameters were determined in three consecutive measurements and were repeated 2 weeks later. The precision within the same session for all parameters was better in the keratoconic eyes, with mean repeatability limits 33% narrower (range 13% to 55%) compared with ICRS eyes. Mean reproducibility limits were 16% narrower (range +48% to -45%) compared with ICRS eyes. The cutoff values to consider a real corneal shape change were lower for virgin keratoconic than for ICRS, except for the thinnest corneal thickness and Stage C (ABCD system), which were the opposite. Corneal tomography measurements in ICRS eyes showed worse accuracy than in virgin keratoconus, which should be taken into account by practitioners in patients' follow up.

Optometric practices and attitudes in keratoconus patient management in Latin America.

CLINICAL RELEVANCE: To explore optometric practices and attitudes in the management of keratoconus patients in LatinAmerica and how they are influenced by eye-care technology will help to minimise disease progression and their impact on patients' quality of life in Latin America. BACKGROUND: Keratoconus is a progressive, bilateral and asymmetric corneal disorder that requires a multidisciplinary approach, the use of different eye assessment technology, and different management approaches; mainly contact lenses and surgery. METHODS: Self-reported answers to an online survey (adapted to primary eye care) distributed via a newsletter emailed by various professional organisations across 15 Latin American countries were assessed and compared with those previously reported in three European countries. RESULTS: Answers from 977 eye care practitioners (60%) with >10 years of experience (396 in Latin America and 581 in Europe) were assessed. A total of 65.9% of Latin American responders prescribed rigid corneal lenses (RCL), although more than half of the respondents (54.0%) would fit more RCL if they underwent further training in RCL fitting. A majority of Latin American practitioners (74.0%) considered that RCL fitting is more difficult in keratoconus, requiring more diagnostic lenses (4.6 ± 2.7; median 4; range 1-10) than are necessary for healthy eyes. Low availability of corneal topography was reported in Latin America (23%), although practitioners with topographers are more likely to prescribe RCL (92.3%) and detect more new patients with keratoconus per year (83.5%). A minority of respondents referred keratoconus patients to another optometrist (25.8%) or (40.4%) participated in comanagement with ophthalmologists. CONCLUSION: This study provides initial evidence regarding keratoconus management in Latin America and suggests that actions are necessary to improve RCL training, facilitate eye-care technology accessibility and encourage comanagement between eye care practitioners to minimise disease progression and their impact on patients' quality of life in Latin America.

Enhanced Depth Imaging Optical Coherence Tomography Technology Reveals a Significant Association Between Optic Nerve Drusen Anterior Displacement and Retinal Nerve Fiber Layer Thinning Over Time.

BACKGROUND: Optic disc drusen (ODD) are a dynamic phenomenon, and their appearance, size, and relative location may change. The purpose of this study is to evaluate and quantify the longitudinal changes of buried ODD with enhanced depth imaging (EDI) optical coherence tomography (OCT) over time. METHODS: ODD were analyzed with Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) and EDI technology. The peripapillary retinal nerve fiber layer (RNFL) thickness was also measured. The size and depth of ODD were compared between the baseline and study visit (at least 2 years of follow-up), and the changes were correlated with mean RNFL thickness. The repeatability, coefficient of variation, and cutoff values for size and depth on EDI-OCT were calculated. RESULTS: Of 21 previously identified patients with ODD, only 12 patients (21 eyes) met the most recent diagnostic criteria according to the ODD Studies Consortium recommendations for using OCT-EDI technology. The 21 eyes were reanalyzed after a mean period of 44.7 ± 13.2 months (range: 24-71 months). Overall, 132 ODD were evaluated with a mean of 6.1 ± 2.5 ODD per eye and 1.9 ± 1.1 ODD per scan. Overall, we found a significant forward movement of the drusen between visits (P = 0.01). Most drusen (67.4%) moved anteriorly, and in approximately one-third (35.6%), this displacement exceeded the cutoff value (64.28 µm). Furthermore, we found a significant correlation between ODD shallowing and RNFL thinning during the follow-up (P ≤ 0.03; R ≥ 0.370). We did not find any significant changes in size measurements (P = 0.10) over time. CONCLUSIONS: In approximately one-third of buried ODD, a significant anterior movement occurred over 2 years of follow-up, and this movement was associated with significant RNFL thinning. By contrast, no significant change was detected in the size of the buried ODD.

Clinical guidelines for the management of keratoconus patients with gas permeable contact lenses based on expert consensus and available evidence.

PURPOSE OF REVIEW: Fitting rigid gas permeable contact lenses (RGP CLs) in keratoconic patients is the most common visual rehabilitation option to improve patients' quality of life, but require long patient and practitioner chair time. The purpose of this review is to provide evidence-based clinical practice guidelines (CPG) in the management of patients with keratoconus with RGP CLs. RECENT FINDINGS: An extensive literature review from 1990 to 2017 identified 354 potentially relevant publications. Fifty-two articles were reviewed and included in the CPG. An international expert panel of eight contact lens practitioners, with vast experience in keratoconus management reviewed and appraised the CPG following the Appraisal of Guidelines for Research and Evaluation II consortium requirements. The developed CPG clearly outlines a strategy for the successful fitting of RGP CLs in patients with keratoconus. This includes how to calculate parameters of the first diagnostic lens, criteria for assessing good fit and a standardized schedule of wear time and follow-up appointments. SUMMARY: The current evidence and consensus-based CPG helps guide clinicians in a successful strategy for fitting RGP CLs in patients with keratoconus.

Classification of Keratoconus Based on Anterior Corneal High-order Aberrations: A Cross-validation Study.

SIGNIFICANCE: Placido disc-based videokeratography is one of the most extensively used methods for corneal topographic assessments in keratoconus. Anterior corneal wavefront analysis has been demonstrated to be an effective tool to manage keratoconus eyes. However, currently, there is no clinically adequate classification system for keratoconus. PURPOSE: The aim of this study was to analyze the usefulness of anterior corneal high-order aberrations in keratoconus classification provided by Placido disc-based videokeratography conducting a cross-validation analysis. METHODS: Corneal topography of 70 normal and 77 keratoconic eyes (divided according to the Amsler-Krumeich classification [n = 21, stage 1; n = 30, stage 2; and n = 26, stage 3]) was assessed using Placido disc-based videokeratography (Oculus Keratograph [Oculus Optikgeräte GmbH, Wetzlar, Germany]). Receiver operating characteristic curve analysis was used to compare the mean values of coma, trefoil, tetrafoil, secondary astigmatism, spherical aberration, and coma-like, third-, and fourth-order root mean square (RMS) to calculate cutoff values, sensitivity, and specificity to discriminate between normal and stage 1 keratoconus eyes and between each keratoconus stage after cross-validation analysis. RESULTS: All wavefront aberrations were significantly different between the normal and keratoconus groups (P ≤ .01). The coma and third-order RMS values (cutoff values, 0.367 and 0.359 µm, respectively) provide better sensitivity (99 and 100%, respectively) and specificity (100%) to discriminate keratoconus (stage 1) from healthy eyes compared with trefoil, tetrafoil, secondary astigmatism, spherical aberration, and coma-like and fourth-order RMS values (sensitivity >84% and specificity >57%). The coma and third-order RMS values showed the highest specificity (100%) and great sensitivity (90 and 87%, respectively) to differentiate between stages 1 and 2 and good sensitivity (97 and 100%) and specificity (81 and 88%) to differentiate between stages 2 and 3. CONCLUSIONS: Anterior corneal high-order aberrations, specifically coma and third-order RMS, could be useful in keratoconus diagnosis and topographical classification. These new cutoff values could improve different stages of keratoconus eyes discrimination.

Gas permeable contact lens fitting in keratoconus: Comparison of different guidelines to back optic zone radius calculations.

Purpose: Compare the agreement between the finally fitted back optic zone radius (BOZR) of a spherical gas permeable (GP) contact lense (CL) with those proposed by different guidelines currently available to fit GP CLs in keratoconus. Methods: The BOZR fitted in 81 keratoconus eyes (46 patients) were recorded and compared with the BOZR calculated with ten different guidelines (identified after a literature review) proposed to calculate the first diagnostic lens BOZR to be fitted in keratoconus. Arithmetic and absolute mean difference between both BOZR were calculated (paired t-test). The success rate of each guideline (difference between both BOZR ≤0.05 mm) was calculated for different keratoconus stages (Amsler-Krumeich classification). Agreement between BOZR was evaluated using Bland-Altman analysis. Results: The BOZR proposed by all guidelines correlated with the final BOZR that was fitted (R2 > 0.71; P < 0.01). A statistically significant difference was found between the BOZR suggested by all guidelines and the BOZR that was prescribed (P < 0.05), except for three Guidelines (P ≥ 0.11). CALCULENS.com presented the best agreement (mean difference of 0.00 ± 0.12 mm), and 50.6% of cases showed ≤0.05 mm of difference with the BOZR that was fitted. However, the worst guideline showed an agreement of -0.38 ± 0.22 mm, and just 3.8% of cases had ≤0.05 mm of difference with the final fitted BOZR. Conclusion: BOZR calculated with most of the analyzed guidelines shows statistical differences with final fitted BOZR, suggesting a lack of clinical validation of these guidelines. The selection of the BOZR with CALCULENS.com could provide a better starting point for spherical GP CL fitting in keratoconus eyes.

A comparison of two optical coherence tomography-angiography devices in pseudoexfoliation glaucoma versus primary open-angle glaucoma and healthy subjects.

PURPOSE: To compare peripapillary vascular parameters derived from two optical coherence tomography angiography devices in pseudoexfoliation glaucoma, primary open-angle glaucoma, and healthy controls and to evaluate their diagnostic accuracy. METHODS: Observational, cross-sectional study. In total, 20 eyes with pseudoexfoliation glaucoma, 20 primary open-angle glaucoma eyes matched by peripapillary retinal nerve fiber layer thickness, and 20 control eyes were recruited. Participants underwent standard automated perimetry and peripapillary retinal nerve fiber layer analysis by Optovue and Cirrus optical coherence tomography. Vascular parameters provided by Angiovue and Angioplex optical coherence tomography angiography were compared. Their diagnostic accuracy and correlation with structural and functional parameters were assessed. RESULTS: All peripapillary optical coherence tomography angiography vascular parameters were significantly different among groups (all p < 0.05). The whole image capillary density and peripapillary capillary density by Angiovue were significantly lower in pseudoexfoliation glaucoma compared with primary open-angle glaucoma (p = 0.009 and p = 0.001, respectively). Conversely, vascular parameters by Angioplex were not statistically different between primary open-angle glaucoma and pseudoexfoliation glaucoma. A good correlation was found using Angiovue between whole image capillary density and visual field mean deviation (0.758, p < 0.001), peripapillary capillary density and visual field mean deviation (0.729, p = 0.001), and peripapillary capillary density and peripapillary retinal nerve fiber layer thickness in eyes with pseudoexfoliation glaucoma (0.716, p = 0.001). Angiovue parameters showed higher area under the receiver operating characteristic curves than Angioplex to discriminate among groups. CONCLUSION: Only Angiovue detected a significantly lower capillary density in pseudoexfoliation glaucoma compared to primary open-angle glaucoma at similar glaucoma damage. Both, Angiovue and Angioplex demonstrated a decreased capillary density in glaucoma eyes compared to healthy eyes. Furthermore, Angiovue-derived vascular parameters showed better correlation with functional and structural parameters and a higher diagnostic capacity to discriminate among groups compared to Angioplex.

Repeatability and Intersession Reproducibility of Pentacam Corneal Thickness Maps in Fuchs Dystrophy and Endothelial Keratoplasty.

PURPOSE: To assess intrasession repeatability and intersession reproducibility of Pentacam corneal thickness maps in patients with Fuchs endothelial corneal dystrophy (FECD) before and after endothelial transplantation. METHODS: In this observational diagnostic evaluation, 20 healthy subjects along with 81 consecutive patients were examined. Patients were classified into 4 groups: FECD without corneal edema, FECD with corneal edema, Descemet stripping automated endothelial keratoplasty, and Descemet membrane endothelial keratoplasty. Three consecutive scans of each eye were obtained at 2 different sessions. Raw pachymetry data were used to calculate average values of 4 concentric annular zones, which were also divided into 8 sectors. Repeatability and reproducibility coefficients (CR), coefficient of variation (CV), intraclass correlation coefficient, and 95% limits of agreement were calculated. RESULTS: The intrasession repeatability CV was ≤1% in the central 6 mm for all groups, with an intraclass correlation coefficient ≥0.97. It was better at the central zone than the periphery in all groups. Intersession reproducibility tended to be worse in the central area than the periphery in FECD without edema (CR ≤ 24.37; CV ≤ 1.48) and FECD with edema (CR ≤ 36.74; CV ≤ 2.03), whereas it was better in the central area in healthy eyes (CR ≤ 20.11; CV ≤ 1.32) and improved after Descemet stripping automated endothelial keratoplasty (CR ≤ 21.93; CV ≤ 1.31) and Descemet membrane endothelial keratoplasty (CR ≤ 30.83; CV ≤ 1.94). CONCLUSIONS: Pentacam corneal thickness maps showed good repeatability and intersession reproducibility in virgin and grafted corneas with FECD, which makes it a valid tool for monitoring these patients. Central areas showed the highest variability between sessions in diseased groups.

Accuracy of Corneal Thickness by Swept-Source Optical Coherence Tomography and Scheimpflug Camera in Virgin and Treated Fuchs Endothelial Dystrophy.

PURPOSE: To assess intraobserver repeatability, intersession reproducibility, and agreement of swept-source Fourier-domain optical coherence tomography (SS-OCT) and the Scheimpflug camera in measuring corneal thickness in virgin and grafted eyes with Fuchs endothelial corneal dystrophy (FECD). METHODS: Thirty-six control eyes, 35 FECD eyes, 30 FECD with corneal edema eyes, 25 Descemet stripping automated endothelial keratoplasty (DSAEK) eyes, and 29 Descemet membrane endothelial keratoplasty (DMEK) eyes were included. The apical center, pupillary center, and thinnest corneal thickness were determined in 3 consecutive images and repeated 2 weeks later. Repeatability and reproducibility coefficients, intraclass correlation coefficients, and 95% limits of agreement (LOA) between measurements were calculated. Agreement between devices was assessed using Bland-Altman analysis. RESULTS: Corneal thickness measurements were highly reproducible and repeatable with both systems. SS-OCT showed better repeatability in all corneal locations in the normal, FECD, FECD with edema, DSAEK, and DMEK groups (coefficient of variation ≤0.60%, ≤0.36%, ≤0.43%, ≤1.09%, and ≤0.48%, respectively) than the Scheimpflug (coefficient of variation ≤1.15%, ≤0.92%, ≤1.10%, ≤1.25%, and ≤1.14%, respectively). Between-session 95% LOA for SS-OCT was less than 3% for all groups except for the FECD with edema group, being almost double using the Scheimpflug camera. Differences between instruments were statistically significant in all groups and locations (P < 0.01) except in the DSAEK group (P ≤ 0.51); however, SS-OCT underestimated all measurements. CONCLUSIONS: SS-OCT provides better reproducible and repeatable measurements of corneal thickness than those obtained with the Scheimpflug camera in patients with FECD or an endothelial transplant. Variations between examinations higher than the 95% LOA observed in our study should raise awareness of changes in the endothelial function.

Intrasession Repeatability and Intersession Reproducibility Measurements Using VX120 Multidiagnostic Unit.

OBJECTIVE: The VX120 multidiagnostic unit is a multidiagnostic instrument that combines several functions: autorefraction, keratometry, corneal topography, aberrometry, pachymetry, and noncontact tonometry. The purpose of this study was to determine the intrasession repeatability and the intersession reproducibility of all parameters measured by the VX120 multidiagnostic unit in a sample of normal healthy eyes. METHODS: Three repeated measurements in the right eye of the volunteers were taken with VX120. Repeatability of the sphere, cylinder, axis, anterior corneal powers (K flat and K steep, 3-mm pupil), high- and low-order aberration root mean square (HOA-RMS and LOA-RMS, 3-mm pupil), eccentricity, white-to-white (WTW), anterior chamber depth (ACD), and central corneal thickness (CCT) (2-mm central) was analyzed. Within-subject SD (Sw), precision, repeatability, coefficient of variation (CV), and the intraclass correlation coefficient (ICC) were calculated. RESULTS: The CV was low for K flat and K steep, WTW, ACD, and CCT with a range from 0.34% to 1.16%. The CV was higher for sphere, cylinder, HOA-RMS, and LOA-RMS and eccentricity with a range among 6.92% to 54.24%. The ICC showed high values in all parameters except in HOA-RMS (0.720-0.776) and eccentricity (0.889) in first session with moderate agreement. Comparing the intrasession repeatability of first and second session, statistically significant differences (P<0.01) were found between both sessions just to the CV for all parameters (except cylinder values) measured with VX120. However, nonstatistically significant differences (P>0.13) were found for Sw, precision, and repeatability values. CONCLUSIONS: The VX120 multidiagnostic unit provides repeatable measurements in anterior corneal power (K flat and K steep), WTW, ACD, and CCT. However sphere, cylinder, HOA-RMS, LOA-RMS, and eccentricity showed worse repeatability. Intersession reproducibility showed good results with little differences between sessions in healthy subjects.

Current optometric practices and attitudes in keratoconus patient management.

PURPOSE: To compare the current optometric practices and attitudes in the management of keratoconus patients in the UK and Spain. METHODS: An online survey (adapted to optometric practices) was distributed via a newsletter emailed by various professional organizations in the UK and Spain. RESULTS: Four hundred and sixty-four practitioners (126 in the UK; 338 in Spain) who prescribed gas permeable GP contact lenses (CLs) more than once per month (54.8% of UK practitioners and 28.1% of practitioners in Spain; p<0.01) responded to the questionnaire. A combination of multiple factors is considered necessary in the keratoconus detection (79.4% in the UK, 75% in Spain; p=0.68), and the use of classification criteria is considered relevant (67.5% in the UK, 70.7% in Spain; p=0.49). There is a high consensus on the consideration that GP CL fitting is more difficult in keratoconus (79.4% in the UK, 80.5% in Spain; p=0.79) requiring more diagnostic lenses (3.2±1.4 and 3.4±1.2 in the UK and Spain, respectively; p=0.72) than are necessary for healthy eyes. Using corneal topography is uncommon from both countries (38.1% in the UK, 59.8% in Spain; p<0.01), with a similar ophthalmologist referral pattern (at initial diagnosis, 50% in both the UK and Spain; p=1.00). Few cases of co-management with ophthalmologists were noted (no co-management reported by 60.3% in the UK and 72.8% in Spain, p=0.01). CONCLUSION: This study provides initial observations and evidence regarding keratoconus management by optometrists in the UK and Spain and shows similarity in the professional practices and attitudes of practitioners in these two countries.

New web-based algorithm to improve rigid gas permeable contact lens fitting in keratoconus.

PURPOSE: To calculate and validate a new web-based algorithm for selecting the back optic zone radius (BOZR) of spherical gas permeable (GP) lens in keratoconus eyes. METHODS: A retrospective calculation (n=35; multiple regression analysis) and a posterior prospective validation (new sample of 50 keratoconus eyes) of a new algorithm to select the BOZR of spherical KAKC design GP lenses (Conoptica) in keratoconus were conducted. BOZR calculated with the new algorithm, manufacturer guidelines and APEX software were compared with the BOZR that was finally prescribed. Number of diagnostic lenses, ordered lenses and visits to achieve optimal fitting were recorded and compared those obtained for a control group [50 healthy eyes fitted with spherical GP (BIAS design; Conoptica)]. RESULTS: The new algorithm highly correlated with the final BOZR fitted (r2=0.825, p<0.001). BOZR of the first diagnostic lens using the new algorithm demonstrated lower difference with the final BOZR prescribed (-0.01±0.12mm, p=0.65; 58% difference≤0.05mm) than with the manufacturer guidelines (+0.12±0.22mm, p<0.001; 26% difference≤0.05mm) and APEX software (-0.14±0.16mm, p=0.001; 34% difference≤0.05mm). Close numbers of diagnostic lens (1.6±0.8, 1.3±0.5; p=0.02), ordered lens (1.4±0.6, 1.1±0.3; P<0.001), and visits (3.4±0.7, 3.2±0.4; p=0.08) were required to fit keratoconus and healthy eyes, respectively. CONCLUSION: This new algorithm (free access at www.calculens.com) improves spherical KAKC GP fitting in keratoconus and can reduce the practitioner and patient chair time to achieve a final acceptable fit in keratoconus. This algorithm reduces differences between keratoconus GP fitting (KAKC design) and standard GP (BIAS design) lenses fitting in healthy eyes.

Success of Rigid Gas Permeable Contact Lens Fitting.

OBJECTIVES: To assess the percentage of successful rigid gas permeable (GP) contact lenses (CLs) fit for both refractive and therapeutic reasons. METHODS: New CLs (soft or GP) fittings were retrospectively analyzed and divided into refractive and therapeutic prescriptions. A standardized fitting protocol that included complete CLs information after a first eye examination, a diagnostic fitting visit, a dispensing visit, and a prescribing visit was used in all fittings. A GP fitting was defined as successful if full-time wear and optimal ocular surface physiology were both achieved at the review assessment 2 to 3 weeks after lens dispensing. RESULTS: Of 232 new CLs fittings analyzed, 166 were refractive fittings (71.6%) and 66 were therapeutic (28.4%). Of the refractive fittings, 88 subjects (53%) were initially fitted with GP CLs and 61 (69.3%) of these met the criteria for successful GP fitting. Within this group, a different percentage of successful fits were found for neophyte (72%), previous soft lens wearers (62%), and previous GP wearers (92.3%). Of the therapeutic fittings, 61 subjects (92.4%) were initially fitted with GP CLs and 59 (96.7%) of these met the criteria for successful GP fitting. CONCLUSIONS: Following a standardized CLs fitting protocol, a relatively high percentage of successful GP fits was achieved for refractive (7/10 subjects) and therapeutic (9/10 subjects) prescriptions. These results will improve the information available to patients and aid in their CL choices by providing them with a realistic attitude. It will also help eye care practitioners in their clinical activities by providing evidence-based information.

Agreement of corneal measurements between dual rotating Scheimpflug-Placido system and Placido-based topography device in normal and keratoconus eyes.

PURPOSE: To compare the anterior corneal measurements between Placido-based topography and dual-Scheimpflug topography in healthy and keratoconus eyes. SETTING: Optometry Research Group, Instituto Universitario de Oftalmobiología Aplicada, University of Valladolid, Valladolid, Spain. DESIGN: Comparative case series. METHODS: The mean simulated keratometry (K), flat K, steep K, astigmatism power, corneal astigmatism axis, J0, J45, maximum corneal power point, and white-to-white (WTW) distance were collected and compared between healthy eyes and keratoconus eyes. RESULTS: The study evaluated in 56 healthy eyes and 56 keratoconus eyes. Placido-based topography underestimated all topographic values except J45 and WTW in healthy eyes and J0, maximum corneal power point, and WTW in keratoconus eyes, with statistically significant differences in astigmatism (healthy), flat K (keratoconus), axis (keratoconus), J0, J45, and WTW (P < .05). Healthy eyes showed better agreement (95% limits of agreement: simulated K -0.13 to 0.40; steep K -0.30 to 0.59; flat K -0.29 to 0.51; astigmatism -0.60 to 0.64; J0 -1.15 to 1.13; J45 -1.10 to 1.20; maximum corneal power point -0.70 to 1.17; WTW -0.96 to 0.76 mm) than keratoconic eyes (simulated K -2.84 to 4.55; steep K -2.80 to 5.21; flat K -3.68 to 4.70; astigmatism -1.90 to 2.95; J0 -2.85 to 3.20; J45 -3.21 to 3.05; maximum corneal power point -7.00 to 4.51 D; WTW -1.00 to 0.88). CONCLUSIONS: Healthy eyes showed better agreement than keratoconus eyes between Placido-based and dual-Scheimpflug topography. Both instruments could be used interchangeably with caution in healthy eyes, but not in keratoconus management. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Advantages, limitations, and diagnostic accuracy of photoscreeners in early detection of amblyopia: a review.

Amblyopia detection is important to ensure proper visual development and avoid permanent decrease of visual acuity. This condition does not produce symptoms, so it is difficult to diagnose if a vision problem actually exists. However, because amblyopia treatment is limited by age, early diagnosis is of paramount relevance. Traditional vision screening (conducted in <3 years) is related with difficulty in getting cooperation from a subject to conduct the eye exam, so accurate objective methods to improve amblyopia detection are necessary. Handheld devices used for photoscreening or autorefraction could offer advantages to improve amblyopia screening because they reduce exploration time to just few seconds, no subject collaboration is needed, and they provide objective information. The purpose of this review is to summarize the main functions and clinical applicability of commercially available devices for early detection of amblyopia and to describe their differences, advantages, and limitations. Although the studies reviewed are heterogeneous (due to wide differences in referral criteria, use of different risk factors, different types of samples studied, etc), these devices provide objective measures in a quick and objective way with a simple outcome report: retest, pass, or refer. However, due to major limitations, these devices are not recommended, and their use in clinical practice is limited.

Repeatability of Wavefront Aberration Measurements With a Placido-Based Topographer in Normal and Keratoconic Eyes.

PURPOSE: To determine and compare the repeatability of anterior corneal higher order aberrations (HOAs) using a Placido-based topographer (Allegro Topolyzer; WaveLight Technologie AG, Alcon Laboratories, Erlangen, Germany) in a sample of normal and keratoconic eyes. METHODS: Three repeated measurements of each cornea of normal and keratoconic eyes were taken with the Allegro Topolyzer. Repeatability of the HOAs (3rd- and 4th-order individual values and normalized polar Zernike coefficients, coma-like, root mean square (RMS) up to 8th-order values, HOA RMS, and total RMS for 6-mm pupil diameter) and central corneal power (3-mm pupil) were analyzed. Within-subject standard deviation (Sw), precision, repeatability, coefficient of variation (CV), and the intraclass correlation coefficient (ICC) were calculated. RESULTS: Zernike coefficients were significantly different between the normal (36 eyes of 36 patients) and keratoconus (36 eyes of 36 patients) groups (P ≤ .03) except in Z(+1) 3, Z(+3) 3, Z(-4) 4, and Z(+4) 4. In the normal group, Sw was 0.031 µm or less, CV ranged from 6.49% (spherical aberration) to 37.18% (secondary astigmatism), and ICC values ranged from 0.227 to 0.982. In the keratoconus group, Sw was 0.059 µm or less, CV ranged from 2.06% (total RMS) to 25.82% (tetrafoil), and ICC values ranged from 0.839 to 0.996. In analyzing the keratoconus stages (Amsler-Krumeich classification), the repeatability of the Zernike coefficients tended to improve with increasing keratoconus stage. CONCLUSIONS: The repeatability of corneal wavefront aberration provided by the Allegro Topolyzer was better in keratoconic eyes (good and moderate repeatability) than in normal eyes (moderate and poor repeatability). These results are important to eye care practitioners and refractive surgeons during refractive surgery planning or keratoconus detection, classification, and management. [J Refract Surg. 2016;32(5):338-344.].

Rigid Gas Permeable Contact Lens Fitting Using New Software in Keratoconic Eyes.

PURPOSE: To determine the repeatability of the back optic zone radius (BOZR) of rigid gas permeable (GP) contact lens (CL) proposed by new software for fitting in healthy and keratoconus eyes and to compare with the diagnostic CL fitting method. METHODS: Three consecutive corneal topographies (Oculus-Keratograph) were performed and analyzed with APEX new software CL fitting (Hecht-Contactlinsen, Germany) in 40 healthy and 40 keratoconus eyes fitted with GP using conventional diagnostic method. The coefficient of variation (CV) of the BOZR suggested by APEX was calculated. The BOZR of both fitting methods (software versus diagnostic) were compared maintaining the same lens diameter. RESULTS: BOZR proposed by APEX showed good repeatability in healthy (CV = 0.32%) and keratoconus eyes (CV = 0.51%). APEX proposed flatter BOZR than the diagnostic method in healthy (7.91 ± 0.24 and 7.84 ± 0.26 mm, p < 0.01) and keratoconus eyes (7.34 ± 0.38 and 7.23 ± 0.37 mm, p < 0.01). A strong linear correlation in healthy (BOZR_Diagnostic_Method = (BOZR_APEX × 1.06) - 0.53; p < 0.01, R = 0.969) and keratoconus eyes (BOZR_Diagnostic_Method = (BOZR_APEX × 0.88) + 0.77; p < 0.01, R = 0.825) was found. A detailed analysis showed a similar trend in different keratoconus stages (Amsler-Krumeich classification); stage 1: 7.42 ± 0.30 and 7.40 ± 0.25 mm, BOZR_Diagnostic_Method = (BOZR_APEX × 0.81) + 1.38, R = 0.973; stage 2: 7.30 ± 0.44 and 7.23 ± 0.38 mm, BOZR_Diagnostic_Method = (BOZR_APEX × 0.84) + 1.07, R = 0.929; and stage 3: 7.33 ± 0.39 and 7.11 ± 0.40 mm, BOZR_Diagnostic_Method = (BOZR_APEX × 0.93) + 0.28, R = 0.831. Applying these regression formulas, the BOZR difference could be reduced in healthy (-0.01 ± 0.05 mm) and keratoconus eyes (-0.01 ± 0.14 mm) for each keratoconus stage (0.01 ± 0.04, 0.03 ± 0.10, and 0.02 ± 0.16 mm in stages 1, 2, and 3, respectively). CONCLUSIONS: APEX software provides repeatable BOZR in healthy and keratoconus eyes, but it tends to propose flatter BOZR than the diagnostic method. APEX BOZR should be improved with new equations and helping with the GP fitting procedure.