To compare and assess the ability of pressure-derived parameters and corneal deformation waveform signal-derived parameters of the ocular response analyzer (ORA) measurement to distinguish between keratoconus and normal eyes, and to develop a combined parameter to optimize the diagnosis of keratoconus.

One hundred and seventy-seven eyes (177 patients) with keratoconus (group KC) and 205 normal eyes (205 patients; group N) were included. One eye from each subject was randomly selected for analysis. Patients underwent a complete clinical eye examination, corneal topography (Humphrey ATLAS), tomography (Pentacam Oculus) and biomechanical evaluations (ORA Reichert). Differences in the distributions between the groups were assessed using the Mann- Whitney test. The receiver operating characteristic (ROC) curve was used to identify cutoff points that maximized sensitivity and specificity in discriminating keratoconus from normal corneas. Logistic regression was used to identify a combined linear model (Fisher 1.0).

Significant differences in all studied parameters were detected (p < 0.05), except for W2. For the corneal resistance factor (CRF): Area under the ROC curve (AUROC) 89.1%, sensitivity 81.36%, specificity 84.88%. For the p1area: AUROC 91.5%, sensitivity 87.1%, specificity 81.95%. Of the individual parameters, the highest predictive accuracy was for the Fisher 1.0, which represents the combination of all parameters (AUROC 95.5%, sensitivity 88.14%, specificity 93.17%).

Waveform-derived ORA parameters displayed greater accuracy than pressure-derived parameters for identifying keratoconus. Corneal hysteresis (CH) and CRF, a diagnostic linear model that combines different parameters, provided the greatest accuracy for differentiating keratoconus from normal corneas.

Luz A, Fontes B, Ramos IC, Lopes B, Correia F, Schor P, Ambrósio R. Evaluation of Ocular Biomechanical Indices to Distinguish Normal from Keratoconus Eyes. Int J Kerat Ect Cor Dis 2012;1(3):145-150.

To compare the results of MyoRing implantation for keratoconus using two different techniques for corneal pocket creation.

Seven eyes suffering from keratoconus were treated using Ziemer LDV for corneal pocket creation and seven eyes suffering from keratoconus were treated using DIOPTEX PocketMaker for corneal pocket creation.

Both groups did not show any statistically significant difference, neither in the severity of the disease nor in the results.

Ziemer LDV and DIOPTEX PocketMaker give equal results for MyoRing implantation for keratoconus.

Daxer B, Mahmood H, Daxer A. MyoRing Treatment for Keratoconus: DIOPTEX PocketMaker vs Ziemer LDV for Corneal Pocket Creation. Int J Kerat Ect Cor Dis 2012;1(3):151-152.

To evaluate anterior surface topographic technologies and display algorithms in mapping keratoconus.

A total of 27 eyes of 17 subjects clinically diagnosed with keratoconus were imaged on six topographers: EyeSys, Alcon EyeMap, Keratron, TMS-1, Orbscan and PAR corneal topography system. Axial distance (AD) and instantaneous radius of curvature (IROC) algorithms were generated, and the cone apex was determined manually using a cursor. Intermachine comparisons for cone magnitude (steepest curvature), as well as cone location in radius and meridian were performed for each display algorithm using both AD and IROC. Significance (p < 0.05) was determined using repeated measures analysis of variance (ANOVA) on successive mean values. Maps were also evaluated for processability, defined by the ability to reconstruct a reasonable map for each subject, not map quality.

There were no significant differences between successive means for cone location in either radial or meridional directions. For AD, Orbscan was greater than both small mire Placido devices (Keratron and TMS-1), which were not different from each other. The small mire devices had significantly greater curvature magnitude than the large mire placido devices (EyeSys, Alcon EyeMap) which were not different from each other. Finally, PAR was significantly lower than the large mire Placido devices. For IROC, the pattern was the same with the exception that the Orbscan was not different than the small mire Placido devices in curvature magnitude. For processing success, the PAR had 100% processability, and all other devices were between 73 and 77%.

In monitoring keratoconus, evaluation of change over time is fundamental to treatment decisions, making understanding of topographic technology differences in mapping keratoconic corneas extremely important.

Markakis GA, Roberts CJ, Harris JW, Lembach RG. Comparison of Topographic Technologies in Anterior Surface Mapping of Keratoconus using Two Display Algorithms and Six Corneal Topography Devices. Int J Kerat Ect Cor Dis 2012;1(3):153-157.

To compare the corneal parameters in normal corneas, forme fruste keratoconus (FFKC) and keratoconus measured with a dual Scheimpflug analyzer.

A total of 372 eyes of 197 patients were prospectively enrolled in the study and divided into three groups: 148 eyes of 102 patients with keratoconus, 47 contralateral topographically normal eyes of clinically evident keratoconus in the fellow eye and 177 eyes of 95 refractive surgery candidates with normal corneas. All eyes were measured with a dual Scheimpflug analyzer and elevation, keratometric, pachymetric and wavefront data were analyzed. Mean and intergroup comparisons were performed for 43 parameters.

Eighty-eight percent of the parameters analyzed (38/43) were significantly different between normal and keratoconus whereas it was less than 40% (17/43) between normal and FFKC. The majority of the elevation parameters were significantly different between normal eyes and FFKC (11/14) whereas the I-S value and the Kmax were the only two parameters related to the anterior curvature that were significantly different between both groups. Corneal vertical coma was the only corneal aberrations significantly different between normal and FFKC (p < 0.07).

The dual Scheimpflug analyzer provides useful parameters for differentiating normal corneas, FFKC and keratoconus.

Smadja D, Touboul D, Colin J. Comparative Evaluation of Elevation, Keratometric, Pachymetric and Wavefront Parameters in Normal Eyes, Subclinical Keratoconus and Keratoconus with a Dual Scheimpflug Analyzer. Int J Kerat Ect Cor Dis 2012;1(3):158-166.

To evaluate the correlations of Pentacam keratometric, topometric (derived from front surface curvature) and tomographic (derived from 3D corneal shape analysis) indices with best corrected visual acuity in patients with keratoconus.

One eye randomly selected of 123 patients with bilateral keratoconus was retrospectively enrolled. All patients underwent a comprehensive ophthalmic examination including subjective refraction, distance best-spectacle corrected visual acuity (DCVA) measurement, and rotating Scheimpflug corneal tomography (Pentacam HR; Oculus, Wetzlar, Germany) at the same office visit. The correlations between the logarithm of the minimum angle of resolution (LogMAR) of DCVA and keratometric indices, topometric indices and tomographic indices were tested with nonparametric Spearman correlation coefficients (?).

The mean LogMAR DCVA was 0.32 (~20/42) ±0.27 [range: −0.10 (20/15) to 1.30 (20/400)]. There were strong correlations between DCVA and many keratometric, topometric and tomographic indices. A strong positive correlation was found between DCVA and BAD-Df (ρ = 0.648, p < 0.001), BAD-Db (ρ = 0.633, p < 0.001), K2 (ρ = 0.643, p < 0.001), K_max (ρ = 0.608, p < 0.001), TKC (ρ = 0.558, p < 0.001), BAD-D (ρ = 0.577, p < 0.001), ISV (ρ = 0.573, p < 0.001), CKI (ρ = 0.530, p < 0.001), KI (ρ = 0.531, p < 0.001). A strong negative correlation was seen between DCVA and Asph Q front 30° (ρ = −0.521, p < 0.001).

There are significant correlations between visual acuity and Pentacam parameters. Such parameters may be considered for improving staging of the disease, as well as for monitoring progression or treatment as outcome measures. There is a potential for combining parameters to enhance the correlations.

Lopes BT, Ramos IC, Faria-Correia F, Luz A, de Freitas Valbon B, Belin MW, Ambrósio R Jr. Correlation of Topometric and Tomographic Indices with Visual Acuity in Patients with Keratoconus. Int J Kerat Ect Cor Dis 2012;1(3):167-172.

To describe clinical findings of cases with keratoconus and concomitant corneal guttata.

Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Brazil.

In a retrospective study including 138 patients with clinical keratoconus, 22 eyes from 11 (8%) patients with keratoconus were identified with the presence of corneal guttata. Complete ophthalmologic examination was performed in all patients, including Scheimpflug rotation tomography (Pentacam HR, Oculus, Wetzlar, Germany), biomechanical study associated with noncontact tonometry [ocular response analyzer (ORA); Reichert, Depew, USA], and specular microscopy (LSM 12000, Bio-Optics, Oregon, USA). The amount of guttata was correlated with biomechanical and tomographic parameters by nonparametric Spearman test.

The mean age was 51.8 ± 20.9 (from 25 to 81) years, nine patients were female (81.9%). The mean of corrected distance visual acuity was 0.20 (20/32) ± 0.49 [from 0 (20/20) to 1.9 (10/800)] LogMar. Eleven eyes had corneal guttae grade I, six eyes grade II, four eyes grade III, and one eye grade IV. The average central keratometric readings were 44.45 ± 2.54 (from 39.70 to 50.60) for flattest K (K1), 46.08 ± 2.69 (from 42.40 to 53.50) for steepest K (K2) and 45.24 ± 2.52 (from 42.00 to 52.20) for average K (Km). Maximal keratometric value (K_max) averaged 47.63 ± 3.10 (from 43.5 to 55.8) D. The mean CCT was 482.54 ± 52.13 µm (from 398 to 585) and in the thinnest point 474.45 ± 50.32 µm (from 387 to 577). The mean of pachymetric progression indices were 0.83 ± 0.41 (from 0.2 to 2.03) (PPI Min), 1.24 ± 0.53 (from 0.7 to 2.73) (PPI Avg), and 1.79 ± 0.92 (from 0.88 to 4.67) (PPI Max). The mean of ART Min was 710.54 ± 372.47 (from 190.64 to 1985), of ART Avg was 433.18 ± 140.96 (from 141.75 to 678.37), and of ART Max was 315.64 ± 122.69 (from 102.78 to 539.78). The mean of front and back elevation at the thinnest point (using best fit sphere to 8 mm) was 5.35 ± 6.77 (from −4 to 20) and 19.15 ± 16.41 (from 1 to 50) respectively. Belin-Ambrósio deviation index (BAD D) was 3.05 ± 3 (from −0.34 to 11.55). The mean corneal hysteresis (CH) was 8.23 ± 2.05 (from 4.1 to 10.9), corneal resistance factor (CRF) was 7.67 ± 2.4 (from 3.4 to 11.3). The amount of guttata was statistically correlated with Km and K1 (Spearman, p > 0.05).

Keratoconus and cornea guttata can coexist in the same patient. This association can camouflage corneal thinning and protrusion associated with ectasia, but elevation, relational thickness, along with combined tomographic indices and biomechanical properties are altered. The diagnosis should be considered in the complete ophthalmic examination, including corneal topography, and tomographic characterization, along specular documentation of corneal endothelium.

Ramos IC, Belin MW, Valbon BF, Luz A, Pimentel LN, Caldas DL, Ambrósio R Jr. Keratoconus associated with Corneal Guttata. Int J Kerat Ect Cor Dis 2012;1(3):173-178.

Barbara R, Abdelaziz L, Barua A, Garzozi H, Barbara A. Collagen Corneal Cross-linking and the Epithelium. Int J Kerat Ect Cor Dis 2012;1(3):179-184.

Kankariya V, Kymionis G, Kontadakis G, Yoo S. Update on Simultaneous Topo-guided Photorefractive Keratectomy Immediately Followed by Corneal Collagen Cross- linking for Treatment of Progressive Keratoconus. Int J Kerat Ect Cor Dis 2012;1(3):185-189.

Barbara R, Abdelaziz L, Pikkel J, Barua A, Garzozi H, Barbara A. Late Onset Post-Lasik Ectasia. Int J Kerat Ect Cor Dis 2012;1(3):190-195.

Carracedo G. Visual Outcomes with Contact Lenses Previous Keratoplasty. Int J Kerat Ect Cor Dis 2012;1(3):196-200.

Rodrigues FD, Santos GC, Gonçalves S, Ferreira CC, Salgado-Borges JM. Sequential Management of Keratoconus Treatment. Int J Kerat Ect Cor Dis 2012;1(3):201-204.

Neuro-ophthalmologic disorders can masquerade as a variety of clinical presentations in pregnant and postpartum women. A high index of suspicion from the ophthalmologist can often avert life-threatening problems.

Shetty R, D’Souza S, Kankariya VP, Srivastava S, Vasavada V, Wadia K. Neurologic Disorder Masquerading as Postpregnancy Progression of Keratoconus. Int J Kerat Ect Cor Dis 2012;1(3):205-208.