Faculty Bibliography

In this brief review we will discuss the reasoning and evolution of our current use of combined very high-fluence collagen crosslinking and laser in situ keratomileusis. Several presentations and pertinent publications are reviewed, along with the key steps of the enhanced LASIK procedure. Long term outcome data support the safety and efficacy of LASIK Xtra in stabilizing myopic but also hyperopic LASIK results.In conclusion, we have compelling evidence that LASIK Xtra is a safe and effective adjunct.

PURPOSE: To report a novel application of collagen cross-linking (CXL) in refractive astigmatic enhancement of previously performed astigmatic keratotomy. METHODS: A 28-year-old woman with prior history of bioptics correction of high myopic astigmatism with femtosecond laser-assisted astigmatic keratotomy followed by topography-guided LASIK showed long-term regression of the astigmatism 4 years later. A novel CXL application was employed in an attempt to reverse the regression of the astigmatic keratotomy. RESULTS: The high fluence CXL intervention resulted in correction of 2 diopters of topographic and refractive cylinder. Uncorrected distance visual acuity changed from 20/50 to 20/20 and refraction from -0.50 -2.00 @ 90 to +0.25 -0.25 @ 90 at the 7-month follow-up. CONCLUSIONS: A possible novel application of high fluence CXL with refractive cornea effect is introduced. It may offer rapid and simple rehabilitation and its effect may be tapered.

PURPOSE: To evaluate the safety and efficacy of a novel LASIK flap patient interface (PI) cone with our reported digital analysis and compare for potential differences with the standard metal and glass PI in flap parameters when used with the Alcon/WaveLight FS200 femtosecond laser. PATIENTS AND METHODS: Thirty-six consecutive LASIK patients (72 eyes) subjected to a bilateral femtosecond assisted LASIK procedure with the novel clear cone PI FS200 1505 were examined for flap diameter and flap thickness over the entire flap area via digital analysis performed on intraoperation image (flap diameter) and anterior-segment optical coherence tomography image (flap thickness). This group was compared with an age- and procedure-matched group B from our practice, in which the standard metal and glass PI was employed. RESULTS: Horizontal flap diameter for group A (clear cone) was 7.87 mm +/- 0.02 mm (range 7.89-7.84 mm) for 8.00 mm programmed, whereas for group B (metal and glass cone) was 7.85 mm +/- 0.04 mm (range 7.93-7.80 mm). Likewise, along the vertical line, flap diameter for group A was 7.84 mm +/- 0.02 mm (range 7.85-7.80 mm) and for group B was 7.83 mm +/- 0.03 mm (range 7.87-7.80 mm). Central flap thickness for group A was 113.29 mum (+/-1.19 mum) for 110 mum planned, 122.1 mum (+/-2.10 mum) for 120 mum planned, and 133.50 mum (+/-0.71 mum) for 130 mum planned. Group B central flap thickness was, accordingly, 112.8 mum (+/-1.25 mum), 122.4 mum (+/-2.15 mum), and 132.50 mum (+/-0.90 mum). The data evaluated (paired group comparisons) between group A and group B did not show statistically significant differences. CONCLUSION: This study indicates that two PIs in use with the FS200 femtosecond laser are safe and have highly reproducible and accurate flap parameter results, such as achieved diameter and flap thickness. The paired group comparisons between the two PIs' respective data do not show statistically significant differences.

PURPOSE: To evaluate safety, efficacy and ease of measurement of epithelial thickness in a keratoconic patient based on anterior segment optical coherence tomography (AS-OCT). METHODS: A 25-year-old male patient, previously diagnosed with keratoconus, with highly asymmetric manifestation among the two eyes, was subjected to AS-OCT corneal epithelial imaging. We investigated epithelial thickness and epithelial topographic thickness distribution. RESULTS: Mean epithelial thickness was 51.97 +/- 0.70 for the less affected right eye (OD), and 55.65 +/- 1.22 for the more affected left eye (OS). Topographic epithelial thickness variability for the OD was 1.53 +/- 0.21 mum, while for the OS it was 9.80 +/- 0.41 mum. CONCLUSIONS: This case further supports our previous findings with high-frequency ultrasound measurements of the increase in overall epithelial thickness in keratoconic eyes in comparison with normal eyes. AS-OCT further offers ease of use and possibly higher predictability of measurement. This case report, based on AS-OCT imaging, verifies increased overall epithelial thickness in keratoconic eyes, as introduced by a previous study [Kanellopoulos et al.: Clin Ophthalmol 2012;6:789-800], based on high-frequency scanning ultrasound biomicroscopy imaging.

BACKGROUND: The purpose of this study is to evaluate the extent and incidence of opaque bubble layer (OBL) using laser-assisted in situ keratomileusis (LASIK) flaps created with the Alcon/WaveLight(R) FS200 femtosecond laser as a result of a recent change in flap programming parameters aiming to reduce further the incidence and extent of OBL. METHODS: Intraoperative digital images of flaps from 36 consecutive patients (72 eyes) subjected to bilateral femtosecond-assisted LASIK were analyzed using a proprietary computerized technique. The incidence and extent of OBL was measured and reported as a percentage of the entire flap area. Flap creation was performed with a 1.7 mm wide canal, implemented as an updated design intended to reduce the extent of OBL (group A). The same OBL parameters were investigated and compared in an age-matched and procedure-matched patients in whom the previous standard setting of a 1.3 mm wide canal was implemented (group B). RESULTS: In group A, the average extent of OBL was 3.69% of the flap area (range 0%-11.34%). In group B, the respective values were 6.06% (range 0%-20.24%). We found the difference to be statistically significant (one-tailed P = 0.00452). CONCLUSION: This study suggests that there is a significant reduction in the incidence and extent of OBL when novel LASIK flap ventilation canal parameters of width and spot line separation are used.

PURPOSE: To evaluate programmed versus achieved laser-assisted in situ keratomileusis (LASIK) flap central thickness and investigate topographic flap thickness variability, as well as the effect of potential epithelial remodeling interference on flap thickness variability. PATIENTS AND METHODS: Flap thickness was investigated in 110 eyes that had had bilateral myopic LASIK several years ago (average 4.5 +/- 2.7 years; range 2-7 years). Three age-matched study groups were formed, based on the method of primary flap creation: Group A (flaps made by the Moria Surgical M2 microkeratome [Antony, France]), Group B (flaps made by the Abbott Medical Optics IntraLase FS60 femtosecond laser [Santa Ana, CA, USA]), and Group C (flaps made by the Alcon WaveLight((R)) FS200 femtosecond laser [Fort Worth, TX, USA]). Whole-cornea topographic maps of flap and epithelial thickness were obtained by scanning high-frequency ultrasound biomicroscopy. On each eye, topographic flap and epithelial thickness variability was computed by the standard deviation of thickness corresponding to 21 equally spaced points over the entire corneal area imaged. RESULTS: The average central flap thickness for each group was 138.33 +/- 12.38 mum (mean +/- standard deviation) in Group A, 128.46 +/- 5.72 mum in Group B, and 122.00 +/- 5.64 mum in Group C. Topographic flap thickness variability was 9.73 +/- 4.93 mum for Group A, 8.48 +/- 4.23 mum for Group B, and 4.84 +/- 1.88 mum for Group C. The smaller topographic flap thickness variability of Group C (FS200) was statistically significant compared with that of Group A (M2) (P = 0.004), indicating improved topographic flap thickness consistency - that is, improved precision - over the entire flap area affected. CONCLUSIONS: The two femtosecond lasers produced a smaller flap thickness and reduced variability than the mechanical microkeratome. In addition, our study suggests that there may be a significant difference in topographic flap thickness variability between the results achieved by the two femtosecond lasers examined.

This case report describes the clinical and histopathologic features, including molecular confirmation, of fungal keratitis after intrastromal corneal ring segments placement for keratoconus. A 52-year-old woman underwent insertion of Intacs(R) corneal implants for treatment of keratoconus. Extrusion of the implants was noted 5 months post insertion and replaced. Three months later, monocular infiltrates and an epithelial defect were observed. The Intacs were removed and the infiltrates were treated with ofloxacin and prednisolone acetate. Microbial cultures and stains were negative. The patient demonstrated flares and exacerbation one month later. Mycoplasma and/or fungus were suspected and treated without improvement. Therapeutic keratoplasty was performed 10 months following initial placement of the corneal ring implants. The keratectomy specimen was analyzed by light microscopy and a panfungal polymerase chain reaction assay. A histopathologic diagnosis of Candida parapsilosis keratitis was made and confirmed by polymerase chain reaction. One year postoperatively, a systemic workup of the patient was done with no signs of recurrence. This rare report of fungal keratitis following Intacs insertion is the first reported case of C. parapsilosis complicating Intacs implantation.

PURPOSE: The evaluation of the safety, efficacy, and long-term stability of LASIK procedures utilizing novel platform comprising a femtosecond and excimer laser and multiple networked diagnostics. SETTING: Private clinical ophthalmology practice. PATIENTS AND METHODS: In consecutive cases of myopic LASIK procedure with a novel refractive platform (FS200 Femtosecond and EX500 Excimer Laser), 190 eyes (from 109 different patients) were evaluated pre- and postoperatively for the following parameters: refractive error, best corrected distance visual acuity, uncorrected distance visual acuity, topography (Placido-disc based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. RESULTS: The change from pre- to postoperative mean refractive error was from -5.29 +/- 2.39 diopters (D) (range -8.0 to -0.50 D) to -0.27 +/- 0.09 D at the 3-month visit, -0.27 +/- 0.10 D at the 6-month visit, and -0.39 +/- 0.08 D at the 1-year visit. The change from pre- to postoperative refractive astigmatism was -1.07 +/- 0.91 D (range -4.25 to 0 D) to -0.14 +/- 0.04 D at 3 months, -0.15 +/- 0.04 at 6 months, and -0.16 +/- 0.04 at the 1-year visit. The proportion of the eyes with postoperative astigmatism within 0.5 D ranged between 95.6% and 99%. The proportion of eyes achieving uncorrected distance visual acuity of 1.0 (decimal) was 93.0%. CONCLUSION: The myopic LASIK clinical results with the FS200 Femtosecond Laser and EX500 Excimer Laser showed outstanding efficacy, great safety, and long-term stability.

PURPOSE: To introduce a novel, noninvasive technique to determine the depth and extent of anterior corneal stroma changes induced by collagen cross-linking (CXL) using quantitative analysis of high-resolution anterior-segment optical coherence tomography (OCT) post-operative images. SETTING: Private clinical ophthalmology practice. PATIENTS AND METHODS: Two groups of corneal cross-sectional images obtained with the OptoVue RTVue anterior-segment OCT system were studied: group A (control) consisted of unoperated, healthy corneas, with the exception of possible refractive errors. The second group consisted of keratoconic corneas with CXL that were previously operated on. The two groups were investigated for possible quantitative evidence of changes induced by the CXL, and specifically, the depth, horizontal extent, as well as the cross-sectional area of intrastromal hyper-reflective areas (defined in our study as the area consisting of pixels with luminosity greater than the mean +2 x standard deviation of the entire stromal cross section) within the corneal stroma. RESULTS: In all images of the second group (keratoconus patients treated with CXL) there was evidence of intrastromal hyper-reflective areas. The hyper-reflective areas ranged from 0.2% to 8.8% of the cross-sectional area (mean +/- standard deviation; 3.46% +/- 1.92%). The extent of the horizontal hyper-reflective area ranged from 4.42% to 99.2% (56.2% +/- 23.35%) of the cornea image, while the axial extent (the vertical extent in the image) ranged from 40.00% to 86.67% (70.98% +/- 7.85%). There was significant statistical difference (P < 0.02) in these values compared to the control group, in which, by application of the same criteria, the same hyper-reflective area (owing to signal noise) ranged from 0.00% to 2.51% (0.74% +/- 0.63%). CONCLUSION: Herein, we introduce a novel, noninvasive, quantitative technique utilizing anterior segment OCT images to quantitatively assess the depth and cross-sectional area of CXL in the corneal stroma based on digital image analysis. Mean cross-sectional area showing evidence of CXL was 3.46% +/- 1.92% of a 6 mm long segment.