Faculty Bibliography

PURPOSE: To evaluate the safety and efficacy of real-time measurement of corneal epithelial thickness and investigate the distribution characteristics in a large normal-eye population using a clinically available spectral-domain anterior-segment optical coherence tomography (AS OCT) system. METHODS: Corneal epithelial thickness distribution and topographic thickness variability were clinically investigated using AS OCT imaging in 373 patients with normal, healthy eyes. Descriptive statistics investigated 3 sets of subgroups, male (n = 171) and female (n = 202), younger (n = 194) and older (n = 179), right eyes (n = 195) and left eyes (n = 197). RESULTS: Pupil center epithelial thickness repeatability was an average 0.88 +/- 0.71 mum; a similar repeatability was noted for the superior, inferior, maximum, and minimum epithelial thickness. On average, the pupil center epithelial thickness was 53.28 +/- 3.34 mum, superior 51.86 +/- 3.78 mum, inferior 53.81 +/- 3.44 mum, minimum 48.65 +/- 4.54 mum, maximum 56.35 +/- 3.80 mum, and topographic variability was 1.78 +/- 0.78 mum. Small differences were noted between male (average center 54.10 +/- 3.34 mum) and female (52.58 +/- 3.19 mum) subjects. The topographic thickness variability seems to increase with age: younger group, 1.65 +/- 0.83 mum; older group, 1.93 +/- 0.90 mum (P = 0.173). CONCLUSIONS: We present a comprehensive investigation of corneal epithelial thickness distribution characteristics in a healthy, untreated human eye population by using in vivo, clinically available Fourier-domain AS OCT. The 3-dimensional epithelial maps reveal epithelial nonuniformity and provide a novel benchmark for future and comparative studies.

PURPOSE: To evaluate the potential influence of corneal cross-linking (CXL) with ultraviolet-A light and riboflavin in keratoconic eyes on several objective parameters of dry eye syndrome. METHODS: This prospective single center study included 30 consecutive eyes of 16 patients that underwent CXL with riboflavin and ultraviolet-A treatment (epithelial removal, 30 minutes soaking with riboflavin, 30 minutes of illumination with 365 nm, 3 mW/cm(2), 5 cm distance). Several dry eye syndrome parameters were evaluated preoperatively and 3 and 6 months after the procedure: intra-individual comparison of fluorescein and Rose bengal staining, height of tear film meniscus, and tear film break-up time. RESULTS: Pathologic staining (more than 10 point-shaped areas or diffuse staining) with fluorescein was evident before CXL in 1 eye, 3 months after CXL in 1 eye, and 6 months after CXL in 1 eye. Rose bengal staining 3 and 6 months postoperatively was comparable to preoperative staining. Tear film height was reduced in 2 eyes before CXL and in 4 eyes 3 months postoperatively, and was normal in all eyes after 6 months. The number of eyes with reduced tear film break-up time was not significantly changed. CONCLUSIONS: CXL had no significant impact on several parameters of dry eye syndrome 3 and 6 months postoperatively.

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: The development of digital, quantitative and accurate analysis of LASIK flap diameter and OBL occurrence.
Method(s): Flaps from 100 consecutive myopic and hyperopic LASIK patients, treated with the Alcon-WaveLight FS200 femtosecond and EX500 excimer lasers were digitally recorded and processed. Flap dimensions and OBL extent was evaluated utilizing a newly-developed digital procedure with a commercially available image processing software. Specifically, the flap creation report image provided by the FS200 internal system was analyzed digitally and calibrated on a scale converting pixels to measurable length in mm. In a similar fashion, the OBL occurrence was measured as a percentage of the actual flap surface area.
Result(s): For the myopic cases, with planned flap diameter 8.00 (n = 20) and 8.50 mm (n = 60), a small negative bias was discovered (- 0.15 mm and -0.12 mm, respectively) with very small size fluctuation (diameter stdev = +/- 0.04 and +/- 0.03 mm, respectively). For the hyperopic cases, with planned flap diameter 9.50 mm (n = 20), a small positive bias was discovered (+ 0.06 mm), again with very small size variation (diameter stdev < 0.009 mm). Of the flaps studied, the majority (> 50%) had negligible or no OBL, and 20% less than 10% of the total flap area. The remaining had OBL to up of 20% of the total flap area. In all cases the flap was 'delayed', that is developing in areas already processed by the femtosecond laser, thus not interfering with the flap creation.
Conclusion(s): this highly accurate, novel validation digital technique confirms the high reproducibility in flap dimensions and small occurrence of OBL in both myopic and hyperopic LASIK cases with the FS200 femtosecond laser

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.

PURPOSE: To report the safety and efficacy of a novel surgical technique using two lasers in cataract surgery. METHODS: In this contralateral eye report, a 57-year-old female underwent cataract extraction. Two laser devices and a standard phacoemulsification, platform were used to conduct the procedures. First, a femtosecond laser was used to perform the corneal incision, capsulorhexis, and initial lens fragmentation in each eye. Following this, a nanosecond laser was used to enter the 2.8 mm incision, uni-axially, and complete the viscoelastic-divided nucleus fragment emulsification and removal in one eye. Standard phacoemulsification was used in the completion of the other eye. Posterior chamber foldable acrylic intraocular lenses were implanted in both cases. We evaluated perioperative acuity, refraction, keratometry, Scheimpflug tomography, intraocular pressure, endothelial cell counts, and total energy used with each laser in each case. RESULTS: Corrected distance visual acuity improved from preoperative 20/60 and 20/70 to postoperative 20/20 in both eyes, with 6-month follow-up. In the right eye, the total intraocular energy used was 2 J by the femtosecond laser and 6 J by the phacoemulsification device. In the left eye, the nanosecond laser utilized the same energy of 2 J and the nanosecond laser 2.4 J (80 pulses of 30 mJ each). There were no other differences noted in intraocular pressure or endothelial cell counts. CONCLUSION: In this report, we introduce a bladeless all-laser cataract surgery extraction alternative technique, with several potential novel advantages: enhanced incision and capsulorhexis reproducibility, reduction in intraocular energy used, and elimination of the potential of thermal corneal injury.

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.