Purpose To analyze the reasons for patient dissatisfaction after phacoemulsification with multifocal intraocular lens (IOL) implantation and the outcomes after intervention. Setting Emory Eye Center, Atlanta, Georgia, USA. Methods This retrospective review comprised eyes of patients dissatisfied with visual outcomes after multifocal IOL implantation. Outcomes analyzed included type of visual complaint, treatment modality for each complaint, and degree of clinical improvement after intervention. Results Thirty-two patients (43 eyes) reported unwanted visual symptoms after multifocal IOL implantation, including in 28 eyes (65%) with an AcrySof ReSTOR IOL and 15 (35%) with a ReZoom IOL. Thirty patients (41 eyes) reported blurred vision, 15 (18 eyes) reported photic phenomena, and 13 (16 eyes) reported both. Causes of blurred vision included ametropia (12 eyes, 29%), dry eye syndrome (6 eyes, 15%), posterior capsule opacification (PCO) (22 eyes, 54%), and unexplained etiology (1 eye, 2%). Causes of photic phenomena included IOL decentration (2 eyes, 12%), retained lens fragment (1 eye, 6%), PCO (12 eyes, 66%), dry-eye syndrome (1 eye, 2%), and unexplained etiology (2 eyes, 11%). Photic phenomena attributed to PCO also caused blurred vision. Thirty-five eyes (81%) had improvement with conservative treatment. Five eyes (12%) did not have improvement despite treatment combinations. Three eyes (7%) required IOL exchange. Conclusions Complaints of blurred vision and photic phenomena after multifocal IOL implantation were effectively managed with appropriate treatment. Few eyes (7%) required IOL exchange. Neodymium:YAG capsulotomy should be delayed until it has been determined that IOL exchange will not be necessary.

Dissatisfaction after multifocal intraocular lens implantation.

Purpose To evaluate the ability of a new combined biomechanical index called the Corvis Biomechanical Index (CBI) based on corneal thickness profile and deformation parameters to separate normal from keratoconic patients. Methods Six hundred fifty-eight patients (329 eyes in each database) were included in this multicenter retrospective study. Patients from two clinics located on different continents were selected to test the capability of the CBI to separate healthy and keratoconic eyes in more than one ethnic group using the Corvis ST (Oculus Optikgerate GmbH, Wetzlar, Germany). Logistic regression was employed to determine, based on Database 1 as the development dataset, the optimal combination of parameters to accurately separate normal from keratoconic eyes. The CBI was subsequently independently validated on Database 2. Results The CBI included several dynamic corneal response parameters: deformation amplitude ratio at 1 and 2 mm, applanation 1 velocity, standard deviation of deformation amplitude at highest concavity, Ambrosio's Relational Thickness to the horizontal profile, and a novel stiffness parameter. The receiver operating characteristic curve analysis of the training database showed an area under the curve of 0.983. With a cut-off value of 0.5, 98.2% of the cases were correctly classified with 100% specificity and 94.1% sensitivity. In the validation dataset, the same cut-off point correctly classified 98.8% of the cases with 98.4% specificity and 100% sensitivity. Conclusions The CBI was shown to be highly sensitive and specific to separate healthy from keratoconic eyes. The presence of an external validation dataset confirms this finding and suggests the possible use of the CBI in everyday clinical practice to aid in the diagnosis of keratoconus. [J Refract Surg. 2016;32(12):803-810.].

Detection of Keratoconus With a New Biomechanical Index

A review of keratoconus: Diagnosis, pathophysiology, and genetics.

Many algorithms exist for the topographic/tomographic detection of corneas at risk for post-refractive surgery ectasia. It is proposed that the reason for the difficulty in finding a universal screening tool based on corneal morphologic features is that curvature, elevation, and pachymetric changes are all secondary signs of keratoconus and post-refractive surgery ectasia and that the primary abnormality is in the biomechanical properties. It is further proposed that the biomechanical modification is focal in nature, rather than a uniform generalized weakening, and that the focal reduction in elastic modulus precipitates a cycle of biomechanical decompensation that is driven by asymmetry in the biomechanical properties. This initiates a repeating cycle of increased strain, stress redistribution, and subsequent focal steepening and thinning. Various interventions are described in terms of how this cycle of biomechanical decompensation is interrupted, such as intrastromal corneal ring segments, which redistribute the corneal stress, and collagen crosslinking, which modifies the basic structural properties. Financial Disclosures Proprietary or commercial disclosures are listed after the references.

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Biomechanics of corneal ectasia and biomechanical treatments.

PURPOSE: To describe pachymetric progression indices (PPI) of the Pentacam HR (Oculus Optikgerate) and the concept of relational thickness, and to test their accuracy for differentiating keratoconic and normal corneas compared with single-point thickness values.

Novel Pachymetric Parameters Based on Corneal Tomography for Diagnosing Keratoconus

Corneal biomechanical metrics and anterior segment parameters in mild keratoconus.

The preoperative evaluation is of critical importance for success in laser in situ keratomileusis (LASIK). This examination should fulfill 3 main purposes: counseling and educating the candidates, surgery planning, and screening for cases at higher risk for complications. It is critical to interview each refractive patient to assess their individual needs and to provide realistic expectations. A thorough ophthalmologic examination is mandatory, including specific complementary examinations to characterize many aspects of the cornea and the optics of the eye. In fact, it is notable that refractive surgery has motivated tremendous development for advanced diagnostic methods, among many others advancements and innovations in Ophthalmology. One of the most important aspects of the preoperative examination of LASIK candidates is to screen cases at risk for progressive ectasia.

Evaluation of corneal shape and biomechanics before LASIK.

PURPOSE To compare corneal hysteresis (CH) and corneal resistance factor (CRF) in eyes with keratoconus with a central corneal thickness (CCT) ≥ 520 μm with CH and CRF in matched controls, and to estimate the sensitivity and specificity of these parameters for discriminating between the two groups. METHODS This prospective, comparative case series comprised 19 eyes of 19 patients with keratoconus with CCT ≥ 520 μm and 19 eyes of 19 healthy sex-, age-, and CCT-matched patients who underwent a complete clinical eye examination, corneal topography, tomography, and biomechanical evaluation. The receiver operating characteristic (ROC) curve was used to identify cutoff points that maximized the sensitivity and specificity for discriminating between groups. RESULTS Central corneal thickness was 543.1 ± 13.9 μm (range: 520 to 568 μm) in the keratoconus group and 545 ± 12.5 μm (range: 527 to 575 μm) in the control group (P=.6017). Corneal hysteresis was 9.22 ± 1.44 mmHg (range: 6.2 to 11.35 mmHg) in the keratoconus group and 10.58 ± 1.91 mmHg (range: 7.34 to 13.53 mmHg) in the control group (P=.0075). Corneal resistance factor was 8.62 ± 1.52 mmHg (range: 5.60 to 11.20 mmHg) in the keratoconus group and 10.30 ± 1.92 mmHg (range: 6.95 to 14.12 mmHg) in the control group (P=.0049). The ROC curve analyses showed a poor overall predictive accuracy of CH (cutoff, 9.90 mmHg; sensitivity, 78.9%; specificity, 63.2%; test accuracy, 71.05%) and CRF (cutoff, 8.90 mmHg; sensitivity, 68.4%; specificity, 78.9%; test accuracy, 73.65%) for detecting keratoconus in the eyes studied. CONCLUSIONS Corneal hysteresis and CRF were statistically lower in the keratoconus group compared with the control group. Given the large overlap, both CH and CRF had low sensitivity and specificity for discriminating between groups.

Ocular response analyzer measurements in keratoconus with normal central corneal thickness compared with matched normal control eyes.

PURPOSE To evaluate corneal biomechanical metrics with tomographic parameters (given by the Oculus Pentacam) and refractive data in a population of healthy Brazilian patients. METHODS Observational, cross-sectional study of 150 consecutive patients (53 men and 97 women; 260 eyes). Age, gender, central keratometric readings (central K), central corneal thickness (CCT), anterior chamber depth (ACD), spherical equivalent refraction, corneal hysteresis, and corneal resistance factor (CRF) were assessed and analyzed. RESULTS Mean patient age was 46.5+/-21.04 years, average central K was 43.59+/-1.54 diopters (D), CCT was 545.05+/-35.41 microm, ACD was 2.96+/-0.52 mm, spherical equivalent refraction was -1.16+/-3.48 D, corneal hysteresis was 10.17+/-1.82, and CRF was 10.14+/-1.8 (range: 5.45 to 15.1). Mean CRF and corneal hysteresis were distinct among gender: CRF 10.326 in women and 9.810 in men (P=.0266); corneal hysteresis 10.421 in women and 9.727 in men (P=.0031). A negative correlation was found between both CRF and corneal hysteresis with age (r=-0.1255, P=.0434; and r=-0.2445, P=.0001, respectively). No association was found between CRF and average central K (r=0.0633, P=.3086), ACD (r=-0.0474, P=.4498), or spherical equivalent refraction (r=0.1028, P=.1061). Corneal hysteresis was not associated with age and average central K (r=0.0572, P=.3573), ACD (r=0.0060, P=.9236), or spherical equivalent refraction (r=0.0975, P=.1253). Corneal resistance factor and corneal hysteresis were positively associated with CCT (r=0.5760, P=0; and r=0.4655, P=0, respectively). CONCLUSIONS Corneal biomechanical metrics of healthy Brazilian patients were associated with CCT, gender, and age. Corneal steepness, ACD, and spherical equivalent refraction did not affect comeal hysteresis and CRF values in the studied population.

Corneal biomechanical metrics in eyes with refraction of -19.00 to +9.00 D in healthy Brazilian patients.

PURPOSE: To correlate parameters derived from corneal deformation resulting from non-contact tonometry integrated with an ultra-high-speed (UHS) Scheimpflug camera (Oculus Corvis ST, Scheimpflug Technology; Wetzlar, Germany) with age in normal eyes from young patients. METHODS: Observational, retrospective study involving one eye randomly selected from study participants, totaling 89 healthy eyes. The Scheimpflug images were taken with an ultra-high-speed camera during each measurement by the corvis ST. The deformation amplitude (DA) and other parameters (e.g., pachy apex, intraocular pressure, 1st A time, highest concavity-time, 2nd A time, 1st A Length, 2nd A Length, Wing-Dist, curvature radius highest concavity, curvature radius normal, Vin, Vout) measured by the corvis ST were correlated with age. The Kolmogorov-Smirnov test was applied, and Spearman's correlation test was utilized to evaluate the parameters measured by the Corvis ST and age. RESULTS: Mean patient age was 27.50 ± 6.30 years. The highest concavity-time was the only studied parameter statistically significantly correlated to age (i.e., p=0.04, rs=0.18). All other corvis parameters were not correlated to age. This included DA (p=0.319), intraocular pressure (p=0.854), pachy apex (p=0.066), 1st A time (p=0.959), 2nd A time (p=0.561), 1st Length (0.552), 2nd Length (p=0.697), Wing-Dist (p=0.769), curvature radius HC (p=0.145), curvature radius normal (p=0.513), Vin (p=0.980) and Vout (p=0.592). CONCLUSIONS: In healthy eyes, age and pressure or biomechanics as derived from the Corvis ST parameters were not associated with exception to highest concavity-time, i.e., the time from starting until the highest concavity is reached.

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Bruno Machado Fontes

Papers

Corneal biomechanical metrics and anterior segment parameters in mild keratoconus.

Evaluation of corneal shape and biomechanics before LASIK.

Ocular response analyzer measurements in keratoconus with normal central corneal thickness compared with matched normal control eyes.

Corneal biomechanical metrics in eyes with refraction of -19.00 to +9.00 D in healthy Brazilian patients.

Effects of age on corneal deformation by non-contact tonometry integrated with an ultra-high-speed (UHS) Scheimpflug camera