9 research outputs found
Comparison of three different diffractıve multifocal intraocular lenses with a +2.5, +3.0, and +3.75 diopter additıon power
Purpose: To compare the functional outcomes and astigmatic tolerability after implantation of multifocal intraocular lenses (IOLs) with a +2.5, +3.0, and +3.75 diopter (D) addition power
Logistic Regression Model Using Scheimpflug-Placido Cornea Topographer Parameters to Diagnose Keratoconus
Purpose. Diagnose keratoconus by establishing an effective logistic regression model from the data obtained with a Scheimpflug-Placido cornea topographer. Methods. Topographical parameters of 125 eyes of 70 patients diagnosed with keratoconus by clinical or topographical findings were compared with 120 eyes of 63 patients who were defined as keratorefractive surgery candidates. The receiver operating character (ROC) curve analysis was performed to determine the diagnostic ability of the topographic parameters. The data set of parameters with an AUROC (area under the ROC curve) value greater than 0.9 was analyzed with logistic regression analysis (LRA) to determine the most predictive model that could diagnose keratoconus. A logit formula of the model was built, and the logit values of every eye in the study were calculated according to this formula. Then, an ROC analysis of the logit values was done. Results. Baiocchi Calossi Versaci front index (BCVf) had the highest AUROC value (0.976) in the study. The LRA model, which had the highest prediction ability, had 97.5% accuracy, 96.8% sensitivity, and 99.2% specificity. The most significant parameters were found to be BCVf (p=0.001), BCVb (Baiocchi Calossi Versaci back) (p=0.002), posterior rf (apical radius of the flattest meridian of the aspherotoric surface in 4.5 mm diameter of the cornea) (p=0.005), central corneal thickness (p=0.072), and minimum corneal thickness (p=0.494). Conclusions. The LRA model can distinguish keratoconus corneas from normal ones with high accuracy without the need for complex computer algorithms
In-vivo corneal biomechanical analysis of unilateral keratoconus
AIM: To evaluate and compare corneal biomechanical findings measured by
ocular response analyzer, topographic and pachymetric findings in
patients with unilateral keratoconus patients and healthy controls.
METHODS: This is an observational, case -control study. Patients with
keratoconus in one eye and forme fruste keratoconus in the fellow eye
were compared with sex and age matched with controls healthy subjects.
All subjects were evaluated with rotating scheimpflug imaging system.
The receiver -operating -characteristic curves were analyzed to evaluate
the sensitivity and specificity of the parameters.
RESULTS: Twenty-seven patients with keratoconus in one eye and forme
fruste keratoconus in the fellow eye were compared with 40 eyes of 40
normal subjects. Corneal hysteresis (CH) was 8.0 +/- 1.7 mm Hg in
keratoconus group, 8.3 +/- 1.6 mm Hg in forme fruste keratoconus group,
and 9.8 +/- 1.6 mm Hg in control groups (P=0.54 between keratoconus and
forme fruste keratoconus groups, P<0.01 between control group and other
groups). Corneal resistance factor (CRF) was 7.1 +/- 2.2 mm Hg in
keratoconus group, 7.8 +/- 1.2 mm Hg in forme fruste keratoconus group
and 9.9 +/- 1.5 mm Hg in control group (P < 0.001 between control group
and other groups). Using receiver-operating-characteristic analysis, the
area under curve values of the parameters to distinguish forme fruste
keratoconus from control subjects were: CH (0.768), CRF (0.866). Best
cut-off points were 9.3 mm Hg and 8.8 mm Hg for CH and CRF respectively.
CONCLUSION: Ocular response analyzer parameters (CH and CRF) are found
to be significantly lower in forme fruste keratoconus patients compared
to normal control subjects