Maja Bohac

Apparent Corneal Ectasia After Bilateral Intrastromal Femtosecond Laser Treatment for Presbyopia.

Purpose: To report a case of apparent corneal ectasia after intrastromal femtosecond laser treatment for presbyopia (INTRACOR). Methods: A healthy 56-year-old male with low hyperopia underwent an unremarkable bilateral INTRACOR procedure in March/April 2011. The patient was discharged after follow-up and returned 5 years later. Results: Before discharge, the monocular logarithm of the minimal angle of resolution uncorrected distance visual acuity (UDVA) values were R, 0.0 and L, 0.10. In both eyes near (UNVA) visual acuities were 0.0. There were signs of slight posterior central corneal steepening without loss of corneal stability. Five years postop, monocular UDVA and UNVA values were 0.4 and 0.0, respectively. Ectasia was observed in both eyes, and the centrally placed 5 concentric rings after the INTRACOR procedure were visible under slit-lamp biomicroscopy. Conclusions: There is no clear reason to explain why the patient developed bilateral corneal steepening. It could be that the patients corneal stromal fibers gradually weakened over this 5-year period.

Vector analysis of astigmatism before and after LASIK: a comparison of two different platforms for treatment of high astigmatism

PurposeTo compare the outcomes of astigmatic laser in-situ keratomileusis (LASIK) procedures between two different platforms using J0 and J45 vector analysis.MethodsPatients were divided into four groups, depending on the type of astigmatism and laser platform on which they were treated. Astigmatism was between 2 and 7 diopters (D). One hundred and thirty-five patients with myopic astigmatism (246 eyes) and 102 patients with mixed astigmatism (172 eyes) underwent unremarkable LASIK correction on Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S laser platform. The preoperative and postoperative sphere, negative cylinder [C] and axis (ø) of manifest refractions were subjected to vector analysis by calculations of the standard J0 (cos [4π(ø-90)/360]xC/2) and J45 (sin[4π(ø-90)/360]xC/2).ResultsReporting the key results, we found J0 significantly reduced after LASIK in both groups (p < 0.001) but not J45. There was no significant association between individual pairs of pre and postoperative J0 & J45 values. There was no significant difference between the outcomes of the two platforms.ConclusionsWavelight Allegretto 400Hz and Schwind Amaris 750S showed excellent results for treating patients with astigmatism, regardless whether it is mixed or myopic astigmatism. The J45 did not reduce significantly possibly because of the low number of eyes with oblique astigmatism. There was no genuine difference post-operatively between groups treated on two different laser platforms according to the vector analyses.

Comparison of Verisyse and Veriflex Phakic Intraocular Lenses for Treatment of Moderate to High Myopia 36 Months after Surgery

ABSTRACT Purpose: To compare refractive stability, endothelial cell count (ECC), incidence of complications, and patients’ satisfaction between a rigid Verisyse (group I, n = 198) and foldable Veriflex (group II, n = 212) phakic intraocular lenses (pIOL) over 36 months postop. Materials and methods: This was a retrospective study. Patients’ satisfaction and incidence of photic phenomena were evaluated at one month and one year postop. Data were analyzed to determine difference between groups for astigmatism, mean spherical equivalent (MRSE), uncorrected (UDVA) and corrected (CDVA) monocular distance visual acuity, complication rate (acute and chronic), and ECC. Differences were considered statistically significant when p < 0.05. Results: Group II cases had significantly higher UDVA, CDVA, and lower astigmatism during the entire follow-up. There was no significant difference in mean MRSE or mean ECC postoperatively. In both groups, mean ECC reduced significantly at one month postop, followed by a gradual linear decline between 1 and 36 months of 22.4 cells/mm2/annum (group I) and 13.32 cells/mm2/annum (group II). Overall complication rates were ≤ 10% with no significant inter-group differences. Group I patients reported lower incidence of halos at one month but more problems with night vision at one year compared with group II. Overall satisfaction was high and total incidence of reported photic phenomena was low. Conclusion: Both Verisyse and Veriflex pIOLs are effective in correcting myopia. The Veriflex lens demonstrated better refractive outcome; however, subclinical inflammation observed in the Veriflex group and potential influence of inflammation on ECC loss require further investigation.

Bowman strip complications during routine LASIK: Two cases demonstrating the clinical advantage of using Mitomicyn C in such cases.

Bowman strip is the term used to describe a portion of Bowman’s layer that remains exposed at the posterior surface of the flap. The incidence of intraoperative complications related to flap creation during LASIK is between 0.19% and 21.2%. Several explanations have been proposed to account for Bowman strip or ‘‘buttonhole’’ complications such as: steep corneas, partially opened eyes, microkeratome deficits such as blade defect and, insufficient synchronization between the movement of the blade and microkeratome translational movement. High astigmatism, or conjunctival entrapment may also lead to Bowman strip or buttonhole flap. Treatment options for Bowman strip appear to depend on the severity of the complications encountered. Some authors recommend waiting three months, relifting the flap, bathing the bed with Mitomicyn C (MMC) followed by surface ablation. In more severe profound cases it is recommended to wait six months, relift the flap, apply of topical MMC, close the flap and re-cutting a new flap. We report our experience of two cases where, the same type of microkeratome and laser platform were used for routine LASIK surgery. In both cases, Bowman strip was encountered with thin strip of epithelium and photo ablation was completed during the two individual surgical events. The only difference was that in one case we applied topical 0.02% Mitomycin C, while in the other the procedure was completed without any additional medications or intervention. Scientific letter

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

ABSTRACT 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. Tomography was performed after 2 years postop. After identifying cases of ectasia, the charts of these patients were examined to identify any common factors that may have predisposed them to develop ectasia. Results: Ten eyes of seven patients developed post-LASIK ectasia. Eight eyes had been treated for myopia and myopic astigmatism, two eyes for mixed astigmatism. There were no cases of ectasia after LASIK for hyperopia. All 10 cases of ectasia had a flap that was created using the Moria M2 mechanical microkeratome (average flap thickness 118.15 ± 12.88 µm) and refractive error corrected using the Wavelight Allegretto excimer laser. Retrospectively, most prevalent risk factors were thin cornea (≤ 500 µm, 50% of cases), anterior topographic map irregularities (e.g., asymmetric bow tie, 40% of cases), Ectasia Risk Score > 3 (40% of cases), percent tissue thickness alteration ≥ 40% (20% of cases) and low residual stromal bed (≤ 300 µm, 30% of cases). One eye had no identifiable risk factors. In the retrospective chart review 14.97% (4,506) of all the eyes had similar risk factors to the cases that went on to develop ectasia. Conclusion: The incidence of ectasia was 0.033% over 8 years. The incidence could be higher as some cases may destabilize beyond this period and some patients were lost to follow-up asymptomatic of any clinical signs. Other intrinsic factors may trigger the development of post LASIK ectasia. The current widely accepted risk factors are not sufficiently rigorous for screening out potential ectasia from developing after LASIK. There is a need to augment accuracy with higher sensitivity and specificity.

A Critical Evaluation of Refractive Outcomes Following LASIK for Moderate to High Astigmatism Using Two Excimer Laser Platforms

PURPOSE To calculate the surgically induced astigmatism (SIA) following LASIK and identify any association between SIA and the target induced astigmatism (TIA) at 1 year postoperatively. METHODS The SIA was calculated using the TIA and residual astigmatism values for [A] myopic astigmatism and [B] mixed astigmatism treated with either the [I] WaveLight Allegretto EyeQ 400-Hz (Alcon Laboratories, Inc. Fort Worth, TX) or [II] Schwind Amaris 750S (Schwind eye-tech-solutions, Kleinostheim, Germany) platforms. The TIA and corresponding SIA results were analyzed using various techniques. RESULTS Key findings were the negative SIA power (y1) was significantly correlated with negative TIA power (x1) and sine of the TIA axis (x2) as follows: [A] I, y1= 0.829x1-0.403x2-0.325 (F = 87.76, r = 0.804, P < .001, n = 127); II, y1= 0.891x1-0.037x2-0.192 (F = 240.06, r = 0.901, P < .001, n = 119) and [B] I, y1= 1.063x1+0.233x2+0.411 (F = 990.99, r = 0.881, P < .001, n = 61); II, y1= 1.029x1-0.115x2+0.322 (F = 270.12, r = 0.908, P < 0.001, n = 111). The sine of negative SIA axis (y2) was significantly correlated with negative TIA power (x1) and TIA axis (x2) as follows: [A] I, y2 = 0.951x2-0.007x1+0.008 (F = 446.58, r = 0.950, P < .001, n = 127); II, y2 = 0.856x2+0.007x1+0.105 (F = 277.18, r = 0.912, P< .001, n = 119) and [B] I, y2 = 0.953x2+0.009x1+0.075 (F = 362.6, r = 0.963, P < .001, n = 61); II, y2 = 0.977x2-0.004x1+0.002 (F = 2910.9, r = 0.990, P < .001, n = 111). CONCLUSIONS The predicted SIA power was up to 12% less than expected in cases of -6.00 diopters cylinder treated for myopic astigmatism using the Allegretto platform. The mean predicted angle of error (the angle between the SIA and TIA axes) was less than 4°, increasing to 12° for against-the-rule astigmatism. The Allegretto platform tended toward a clockwise axis rotational error, whereas the Amaris platform tended toward the opposite. [J Refract Surg. 2017;33(2):104-109.].

One Year Follow-Up After Veriflex Phakic Intraocular Lenses Implantation for Correction of Myopia.

Objectives: The aim of this study was to evaluate visual and refractive outcomes after Veriflex phakic intraocular lenses (pIOL) implantation in moderately myopic eyes as well as postoperative complications. Methods: This prospective clinical study included 40 eyes of 26 patients which underwent implantation of Veriflex for correction of myopia from -6.00 to -14.50 diopters (D) in the Eye Clinic Svjetlost Sarajevo, from January 2011 to January 2014. Uncorrected distance visual acuity (UDVA), manifest residual spherical equivalent (MRSE), intraocular pressure (IOP), endothelial cell (EC) density were evaluated at one, three, six and 12 months. Other complications in postoperative period were evaluated. For statistical analysis SPSS for Windows and Microsoft Excel were used. Results: Out of 26 patients 14 had binocular and 12 monocular procedure, with mean age of 29.8±6.5 years. After 12 months mean UDVA was 0.73±0.20. Mean MRSE was -0.39±0.31D and 90% of eyes had MRSE within ±1D. EC loss was 7.18±4.33%. There was no significant change of IOP by the end of 12 months follow up period. The only intraoperative complication was hyphema and occurred in one eye. Few postoperative complications were: subclinical inflammation in three eyes (7,5%), pigment dispersion in four eyes (10%), ovalisation of papilla in 2 eyes (5%) and decentration of pIOL in 2 eyes (5%). Conclusion: Implantation of iris-claw phakic lenses Veriflex for treating moderately high myopia is a procedure with good visual and refractive results and few postoperative complications.

Ocular Aberrations and Corneal Thickness-Intraocular Pressure Relationship One Year after Laser in situ Keratomileusis (LASIK) Enhancement with An Aspheric Ablation Profile

Objective: To evaluate the effect of an aspheric LASIK refractive enhancement performed by relifting the original flap on the higher order aberrations (HOA) of the eye and the relationship between central corneal thickness (CCT) and intra-ocular pressure (IOP). Methods: Consecutive case series of 30 eyes requiring refractive enhancement from 1804 uncomplicated primary LASIK procedures performed in 2012. Flap relift and wavefront optimized ablation (Wavelight Allegretto Eye Q 400 Hz excimer laser) were performed in all cases. Pre-and post-operative examination included Shack-Hartmann aberrometry for 3 mm and 5 mm pupil sizes, CCT and IOP. Postoperative results at 1 year were compared to baseline values. Results: Changes in average values of coma, spherical aberration (SA), trefoil, CCT and IOP were not significant. Linear regression revealed significant associations between change (y) in trefoil and pre-enhancement value of trefoil for 3 mm pupil (0.828x-0.045, r=0.722, p<0.001), coma and pre-enhancement value of coma for 5 mm pupil (y=0.281x-0.030, r=0.501, n=30, p=0.048), SA for 3 mm pupil compared with change in CT (y=0.0080-0.0009x, r=-0.378, p=0.0392), and SA for 5 mm pupil compared with change in CCT (y=0.0035x-0.0541, r=0.524, p=0.0029). Also there was a significant association between IOP and CCT both pre-(IOP=0.0313CT-3.3, r=0.740, p<0.0001) and post-enhancement (IOP=0.0243CT-0.018, r=0.675, p<0.0001). Conclusion: LASIK enhancement with an aspheric ablation profile did not significantly impact on the average values for HOAs, IOP or CCT. For individual cases, the likely shift in magnitude of coma, trefoil and SA can be estimated and, the change in SA is correlated with changes in CCT. The change in the abscissa value linking IOP with CCT may be an indication of changes in biomechanical properties of the cornea in the central region.