Fluctuations of Anterior Chamber Depth and Astigmatism in Pseudophakic Eyes.

Purpose: To explore the significance of changes in anterior chamber depth (ΔACD) and astigmatism between 4 and 8 weeks following uneventful phacoemulsification.

Patients And Methods: Anterior chamber depth (ACD, mm), autorefractometry and subjective refraction were monitored in pseudophakic eyes implanted with non-toric IOLs (group 1, SA60AT, n=36; group 2, SN60WF, n=34; group 3, ICBOO, n=16) and phakic control group (n=30, group 4a, for ACD and autorefractometry) over four weeks. Changes in subjective refractions were compared with repeatability in normal phakic eyes (n=30, group 4b).

The Impact of Standard Cross-Linking on the Corneal Optical Density-Age Relationship in Keratoconus After Mechanical Stripping of the Epithelium.

To determine if cross-linking (CXL) treatment modifies any pre-existing association between corneal optical density (COD) and age in keratoconus free of corneal scarring. COD was monitored in two groups (i) before and after standard CXL treatment for keratoconus (de-epithelization with a crescent blade,  = 69 eyes) and (ii) age/gender-matched cases without any signs of keratoconus ( = 24 eyes). Seven different markers of COD were quantified using a 0-100 grey scale, supplied with Pentacam™ software.

Could Automated Objective Measurements Acquired at the Preoperative Stage Estimate the Corrected Distance Visual Acuity after Corneal Cross-Linking in Keratoconus?

Introduction: Objective markers describing corneal optical density (COD), thinnest corneal thickness (TCT), and anterior (ARC) and posterior (PRC) surface radii over the 3 mm thinnest region of the cornea were investigated to provide a model for estimating corrected distance visual acuity (CDVA) after corneal cross-linking (CXL) in keratoconus.

Methods: CDVA, COD, TCT, ARC, and PRC were monitored (using Pentacam™) over 1 year in patients with (1) keratoconus treated with routine CXL (2) relatively stable untreated keratoconus, and (3) age/gender-matched controls.

Results: In group 1 (n = 77), the median logMAR CDVA (mode, interquartile range) improved significantly (p < 0.

Stereoacuity and Aniseikonia: Evaluation Before and After Bilateral Implantation of Three Types of Presbyopia-Correcting Intraocular Lenses in Uncomplicated Phacoemulsification with Due Consideration of Interocular Differences in Higher Order Aberrations, Axial Lengths, Refractive Errors, and Acuities.

Purpose: To determine if the changes in stereoacuity and aniseikonia, following bilateral implantation of presbyopia correcting intraocular lenses could be predicted from preoperative measurements of higher order aberrations (HOAs), axial lengths (AL), refractive errors (RE) and corrected visual acuities (CVAs).

Patients And Methods: Stereoacuity (Randot tests, @6m & 40cm, in steps of 20 arcsecs") vertical and horizontal aniseikonia (Awaya test @6m, in steps of 1%) with best correction and HOAs (Shack-Hartmann aberrometer) were measured before, 3 and 6 months after uncomplicated bilateral phacoemulsification. Twenty patients (I) underwent a mix-and-match procedure (Tecnis MF, ZKB00 in one eye and ZLB00 in the other), 17 (II) were implanted with a trifocal (AT LISA 839 triMP) and 18 (III) with a one-piece diffractive (Synergy OU) intraocular lens.

Corneal Surface Elevation and Thickness in Relation to the Fit of Rigid Contact Lenses in Keratoconus and After Corneal Cross-Linking.

Purpose: To determine if factors pertaining to corneal thickness and elevation were linked to the prescribed back optic zone radius and overall diameter in keratoconus (group I), and cross-linked keratoconus (group II), cases successfully fitted with rigid contact lenses.

Patients And Methods: A review of cases adapted to contact lens wear (Rose K™) and assessed using Pentacam™ (for corneal anterior surface topography, astigmatism, elevation, and topographic thickness variation) was undertaken to determine the significance of any correlation with comfort, lens usage, grading of keratoconus, corrected distance visual acuity (with glasses and contacts), refractive error, prescribed lens powers, back optic zone radius and overall diameter values were assessed.

Results: Chief findings were, comfort was rated highly, lenses were worn for more than 10 hours/day in 75% of cases.

A Critical Assessment of Friedenwald's Technique for Estimating the Coefficient of Rigidity of the Cornea.

Purpose: To determine if Friedenwald's technique for estimating the coefficient of corneal rigidity (Ko, units mmHg/L), could differentiate between the cornea in keratoconus, normal eyes, and after crosslinking (CXL).

Methods: Two operators (1 and 2) independently measured Ko in three groups (keratoconus, normal, and post-CXL corneas), and repeated the procedure in some where their care remained unchanged and others after routine CXL (>28 days postop, epi-off treatment, 3.0 mW/cm, 30 min).

Prevalence of keratoconus in refractive surgery practice population in North Macedonia.

Purpose: To determine the prevalence of keratoconus (KC) in relation to ethnicity in a group of people who consulted an ophthalmological care institution seeking for refractive surgery in N. Macedonia.

Methods: This was a cross-sectional, interventional retrospective study.

The relationship between angle kappa and astigmatism after phacoemulsification with implanting of spherical and aspheric intraocular lens.

Purpose: To determine the significance of any association between either change in angle kappa (Κ°) or the rectilinear displacement (L, mm) of the first Purkinje image relative to the pupil center and unexpected changes in astigmatism after phacoemulsification.

Methods: Orbscan II (Bausch and Lomb) measurements were taken at 1, 2, and 3 months after unremarkable phacoemulsification in patients implanted with spherical (group 1, SA60AT, Alcon) or aspheric (group 2, SN60WF, Alcon) nontoric IOLs. The outputs were used to calculate L.

Comparison between the change in total corneal astigmatism and actual change in refractive astigmatism in transepithelial photorefractive keratectomy (tPRK), laser in situ keratomileusis (LASIK) and femtosecond laser assisted laser in situ keratomileusis (FsLASIK).

Purpose: To compare changes in astigmatism by refraction and total corneal astigmatism after tPRK, LASIK and FsLASIK.

Setting: Specialty Eye Hospital Svjetlost, Zagreb, Croatia.

Design: Partially masked, semi-randomized, prospective, case-by-case, interventional, clinical study.

A critical evaluation of longitudinal changes of astigmatism following implantation of toric implantable collamer lens (TICL): a comparison between treated and untreated cases over 4 years.

Purpose: To evaluate residual astigmatism following correction with toric implantable collamer lens (TICL) (group I) over a period of 4 years and compare with the change of astigmatism in spectacle wearers (group II).

Methods: Groups I (86 cases implanted with TICL [EVO + Visian ICL, Staar Surgical, Nidau, Switzeland], preop refractive error [sphere and cylinder] - 22.25 DS to - 1.

Spotlight on the Corneal Back Surface Astigmatism: A Review.

Recent evidence indicates that the corneal back surface astigmatism (CBSA) contributes to the refractive state of the eye in cataract surgery, especially with the implantation of toric intraocular lenses. But this has been met with some scepticism. A review of key studies performed over the past three decades shows that the mean CBSA power ranges from 0.

The effect of corneal crosslinking on the rigidity of the cornea estimated using a modified algorithm for the Schiøtz tonometer.

Purpose: The aim of this study was to test a method for estimating corneal rigidity before and after cross-linking (CXL) using a Schiøtz tonometer.

Methods: The study was performed in the Kyiv City Clinical Ophthalmological Hospital "Eye Microsurgical Center", Ukraine. This was a prospective, consecutive, randomized, masked, case-by-case, clinical study.

Predicted and Measured Changes in Posterior Corneal Astigmatism after Uncomplicated Femtosecond Assisted LASIK (FsLASIK) and Microkeratome LASIK Correction for Myopia and Low Astigmatism.

: To compare predicted and measured changes in astigmatism at the posterior corneal surface (PCS) after FsLASIK or LASIK.: Astigmatism was measured at both corneal surfaces (Pentacam) before and 3 months after unremarkable FFsLASIK (roup 1,n = 100) or LLASIK (roup 2,n = 100) for myopia (-7.25DS to -0.

The influence of routine uncomplicated phacoemulsification on the orthogonality of the cornea.

Purpose: The aim of this study was to determine the effect of routine uncomplicated phacoemulsification on the orthogonal distribution of mass within the central optical zone of the cornea.

Methods: Astigmatism at both corneal surfaces was evaluated using Orbscan II (Bausch &and Lomb) before and up to 3 months after routine phacoemulsification (one eye/patient). The data were subjected to vector analysis to estimate the pre-and postoperative total astigmatism of the cornea (TCA).

Are changes in visual acuity and astigmatism after corneal cross-linking (CXL) in keratoconus predictable?

Purpose: To evaluate changes in corrected distance visual acuity (CDVA), ratio of anterior and posterior corneal radii over the thinnest region of the cornea (ARC/PRC), and astigmatism after cross-linking (CXL) in keratoconus.

Methods: Subjective refraction and ARC/PRC (using Pentacam™) were monitored over 1 year in (I) keratoconus treated with routine CXL (n = 53), (II) relatively stable keratoconus (n = 23), and (III) age/gender matched controls (n = 24).

Results: CDVA (median, mode, interquartile range) improved significantly in group I, compared with groups II and III (p < 0.

The Impact of Changes in Corneal Back Surface Astigmatism on the Residual Astigmatic Refractive Error following Routine Uncomplicated Phacoemulsification.

Purpose: To determine the significance of any association between intersessional changes in ocular residual astigmatism (RA) and astigmatism at corneal front (FSA) and back (BSA) surfaces following uneventful routine phacoemulsification.

Methods: Astigmatism was evaluated by autorefractometry and subjective refraction and at both the corneal surfaces with Orbscan II™ (Bausch & Lomb) over central 3 mm and 5 mm optical zones at 1, 2, and 3 months after routine phacoemulsification in 103 patients implanted with monofocal nontoric intraocular lenses (IOLs, one eye/patient). Data were subjected to vector analysis to determine the actual change (Δ) in astigmatism (power and axis) for the refractive and Orbscan II findings.

The relationship between patient age and residual refractive error after uneventful laser in situ keratomileusis for moderate-to-high hyperopia.

Purpose: To determine if the manifest sphero-cylindrical residual refractive error, at various time points over a 12-month postop period after laser in situ keratomileusis (LASIK) was associated with patient age at time of surgery.

Methods: Patients with moderate to high hyperopia (3.00-7.

Vector Analysis of Changes in the Higher Order Ocular Aberrations and Central Corneal Thickness After T-PRK and Fs-LASIK.

Introduction: Refractive surgery procedures, transepithelial photorefractive keratectomy (T-PRK) and femtosecond laser in situ keratomileusis (Fs-LASIK) are regarded as safe and efficacious methods for correcting myopia and myopic astigmatism. These two methods do not have much differences in results when treating spherical myopia, while some differences does exist in treatment of myopic astigmatism. Vector analysis presents powerful tool to show the real differences between these two methods regarding higher order ocular aberrations and central corneal thickness of treated eyes.

The impact of exposure on the magnitude of astigmatism formed within the precorneal tear film over the central optical zone of the cornea in ocular surface disease.

Purpose: To estimate the astigmatic power and axis of the tear film over the central optical zone of the cornea by vector analysis of topographic data, in ocular surface disease (OSD) and controls, during blink suppression.

Methods: Video-keratoscopic images were captured on opening the eyes after a single blink 5, 10 & 15 s later during blink suppression in OSD patients (mixed aetiology, group 1 age 20 - 50 years, n = 12, group 2 > 50 years, n = 38) and controls (group 3, n = 19). The SimK and axis values were used to calculate the astigmatism (power and axis) that formed in the precorneal tear film during each period.

Cross-linking treatment for better visual acuity.

Aim To correlate the maximum anterior sagittal curvature (Kmax) changes and uncorrected (UDVA) and corrected distance visual acuity (CDVA) in keratoconus patients after the cross-linking (CXL) procedure. Methods Forty-four eyes of 34 patients with keratoconus were analysed after the standard Dresden protocol CXL procedure had been performed. All patients underwent complete preoperative examination with a follow-up of 12 months with focus on UDVA, CDVA and Oculus Pentacam (Scheimpflug technology) analysis.

Treatment of High Astigmatism with WaveLight Allegretto Eye-Q Excimer Laser Platform.

Introduction: The WaveLight Allegretto Eye-Q is a flying-spot excimer laser, with a pulse repetition rate of 400Hz, with two galvanometric scanners for positioning laser pulses. The system has an infrared high speed camera operating at 400Hz to track the patient's eye movements that either compensates for changes in eye position or interrupts the treatment if the eye moves outside a preset predetermined range.

Aim: The purpose of this study was to investigate WaveLight Allegretto Eye-Q 400Hz laser delivery platform aimed to correct astigmatism by subjecting the pre and postoperative astigmatic values to vector analysis.

The relationship between clinical measures of aniseikonia and stereoacuity before and after LASIK.

Purpose: To determine the significance of changes and and inter-relationships between three markers of binocular function (aniseikonia, distance and near stereoacuity) following unremarkable LASIK at 3 and 6 months postoperatively.

Methods: All patients underwent LASIK using the Schwind Amaris 750S and the flaps were created using Intralase 150 kHz. Patients were I, monocular myopes II, binocular myopes III, binocular hyperopes IV, binocular astigmats V, anisometropes and VI, matched age and gender control (n = 20 in each group except III where n = 18).

Changes in Endothelial Cell Count Up to Three Years After Implantation of Toric Implantable Collamer Lenses.

Purpose: To determine the temporal effect of toric implantable collamer lens (TICL) implantation and location on corneal endothelial cell density (ECD) over a period of 36 months after surgery.

Methods: ECD [number of cells per square millimeter estimated using the Specular Microscope SP-1P (Topcon Europe Medical B.V.

The refractive index of the human cornea: A review.

The refractive index of the cornea and overlying tear film are key factors affecting refraction and overall optical properties of the eye. A figure of 1.376 is often quoted for the refractive index of the human cornea over the visible spectrum.

Incidence and Clinical Characteristics of Post LASIK Ectasia: A Review of over 30,000 LASIK Cases.

Purpose: To report the incidence of postoperative ectasia after laser in situ keratomileusis (LASIK).

Methods: A retrospective case review of 30,167 eyes (16,732 patients) was conducted following LASIK between August 2007 and August 2015. The follow-up was between 2 and 8 years.