Suboptimal visual outcome after femto-LASIK ablation in a high myopic patient.

A 28-year-old nurse had an aberration-free femto-laser in situ keratomileusis (LASIK) performed for her myopia of -6.25 -0.50 × 096 and -6.75 -0.50 × 175 in the right and left eye, respectively. Corrected distance visual acuity (CDVA) preoperatively was 20/16. Preoperatively, there were no abnormalities on Scheimpflug imaging, and a pachymetry of 585 µm was measured in both eyes. Flap thickness was 115 µm. The patient was quite nervous during the surgery. Since the surgery, her uncorrected distance visual acuity (UDVA) and CDVA are suboptimal at 20/30 and 20/20 in the right eye, and 20/20 and 20/16 in the left eye. 3 months postoperatively, there is a stable manifest refraction of +0.25 -1.25 × 030 and +0.25 -0.00 × 0. The keratometric astigmatism in the Scheimpflug imaging is 1.2 diopter (D) × 114 and 0.4 D × 78 in the right and left eyes, respectively (FIgures 1 and 2). Thinnest pachymetry is 505 µm and 464 µm in the right and left eye, respectively. Her wavefront analysis shows refraction in a 6 mm zone of -0.99 -1.22 × 32 and -0.91 -0.36 × 136. The cycloplegic refraction is 1.25 -1.00 × 023 and +1.00 -0.25 × 006 (Figures 3 and 4). What is the cause of the suboptimal visual outcome in this case? What would be your treatment strategy to improve visual outcome?

Vascular access flow reduction for arteriovenous fistula salvage in symptomatic patients with central venous occlusion.

PURPOSE: Vascular access patients with central vein (CV) stenosis or occlusion may have significant symptoms. Treatment is generally by balloon angioplasty, with or without stenting. However, CV lesions may not be correctable and when treated, tend to recur. Surgical bypass of CV obstruction is a major procedure and ligation of the access may leave the patient dependent on catheter dialysis. We review a precision inflow banding procedure to limit vascular access flow and pressure for symptomatic patients with CV obstruction while preserving access functionality. MATERIALS AND METHODS: All individuals with symptomatic CV occlusive disease who underwent an autogenous vascular access inflow restriction procedure by the two senior authors were identified. All had failed attempts to correct CV lesions by angioplasty and stent placement. A precision banding procedure was used for access inflow reduction with the addition of real-time intravascular flow monitoring. RESULTS: Twenty-two patients were identified. Ages were 22-72 years (mean=43 years). Nine patients (40.9%) were women, and 8 (36.4%) obese. Mean access flow was 1640 mL/minute before banding decreased to 820 mL/minute after banding (P< .01). All patients had access salvage. Swelling resolved promptly in 20 patients and was markedly improved in two individuals. Three patients underwent aneurysm repair with simultaneous inflow banding and decreased intra-access pressure after flow restriction. Two fistulas failed at eight and 13 months. Mean follow-up was 8 months. CONCLUSIONS: The symptoms of hemodialysis vascular access patients associated with non-correctable central venous lesions resolved successfully and their access was maintained using a precision inflow banding procedure.

Capsular block syndrome associated with femtosecond laser-assisted cataract surgery.

UNLABELLED: We report intraoperative capsular block syndrome occuring during the first 50 femtosecond laser-assisted cataract surgeries performed in our facility. Two patients had uneventful combined laser fragmentation, capsulotomy, and corneal incision procedures. In both cases, following transfer to the operating room and manual removal of the laser-cut capsulotomy, posterior capsule rupture was noted during hydrodissection, resulting in posterior dislocation of the lens. Pars plana vitrectomy, removal of the crystalline lens, and sulcus implantation of an intraocular lens were performed in both patients with good visual outcomes. Femtosecond laser-assisted cataract surgery changes the intraoperative environment with the generation of intracapsular gas and laser-induced changes in the cortex. With awareness of the changed intraocular environment following laser lens fragmentation and capsulotomy and a modification of the surgical technique, no additional cases of intraoperative CBS have been seen in more than 600 laser-assisted cataract surgery procedures performed to date at our facility. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.

Fulfilling the promise of laser refractive surgery.

PURPOSE: To review the characteristics required to perform accurate and precise laser refractive surgery relative to the current state of the art and the technology improvements needed in the future. METHODS: The general characteristics for laser refractive surgery are identified and their relative contributions to a successful result considered. For each characteristic, the degree to which improvements in technology are likely to improve results is discussed. RESULTS: The environment (surgeon, site), technology (laser, aberrometer), and patient are identified as key factors affecting results. Although aberrometers appear to be clinically sufficient, improvements in laser beam characteristics and delivery should improve system consistency. Current registration technology may be a factor in variability from patient to patient, but the greatest contribution in this regard would appear to be patient biomechanical and healing response factors. CONCLUSIONS: Wavefront-guided laser refractive surgery has demonstrated an ability to be better than conventional surgery. Improvements in laser technology, registration technology, and biomechanical diagnostics are expected to further improve results. These potential improvements are expected to reduce variability and suggest that the final potential of this technology has not yet been realized.

Laser in situ keratomileusis for refractive error after cataract surgery.

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) to correct refractive error following cataract surgery. SETTING: The Eye Institute, Sydney, Australia. METHODS: This retrospective study reviewed 23 eyes (19 patients; 10 female, 9 male) treated with LASIK for refractive error following cataract surgery. The Summit Apex Plus and Ladarvision excimer laser and the SKBM microkeratome were used. The mean age was 63.5 years (range 50 to 88 years). The mean length of follow-up was 8.4 months (range 1 to 12 months) and mean interval between cataract surgery and LASIK was 12 months (range 2.5 to 46 months). RESULTS: The mean preoperative spherical equivalent refraction (SEQ) for myopic eyes was -3.08 +/- 0.84 diopters (D) (range -4.75 to -2.00 D) and for hyperopic eyes was +1.82 +/- 1.03 D (range +0.75 to +3.00 D). The mean improvement following LASIK surgery was greater for myopic than hyperopic eyes (myopic, 2.54 +/- 1.03 D versus hyperopic, 1.73 +/- 0.62 D; P=.033). The percentage of patients within +/-0.5 D of intended refraction post-LASIK surgery was 83.3% for myopic eyes and 90.9% for hyperopic eyes and all eyes were within +/-1.0 D of intended (P<.001). The percentage of eyes with uncorrected visual acuity of 20/40 or better in the myopic group improved from none preoperatively to 91.7% postoperatively (P<.001) and in the hyperopic group improved from 27.3% preoperatively to 90.9% postoperatively (P=.008). No eyes lost 2 or more lines of best corrected visual acuity. CONCLUSION: Laser in situ keratomileusis appears to be effective in correcting refractive error following cataract surgery. Longer-term studies are required to determine refractive stability.

Wavefront's role in corneal refractive surgery.

In the 5 years since the first wavefront-based LASIK treatment on normal eyes, the ophthalmology profession has had to confront a new language based on astronomy, optics and mathematics. Over this time wavefront technology has been used for diagnosis and treatment, and its application has made the profession define what is meant by good vision, and determine whether, with psychophysical and psychometric tests, it is possible understand how an individual perceives the world. The clinical application of wavefront technology has forced ophthalmologists and vision scientists with an engineering bias to talk to those with a biological bias, and to appreciate that if you try and change the corneal shape, its biological, anatomical and optical properties exist within a complex external eye environment. This perspective article demonstrates that wave-front analysis is a useful diagnostic tool, and that wavefront-based corneal refractive surgery is an improvement over conventional techniques. Its use by an ophthalmologist is a clinical decision specific to an individual patient.

Development of a questionnaire to assess subjective vision score in myopes seeking refractive surgery.

PURPOSE: To assess vision in patients with myopia and myopic astigmatism before and after refractive surgery. METHODS: A prospective controlled study of visual quality amongst myopes and astigmatic myopes. Focus groups, ophthalmic surgeons, and questionnaire experts devised a Subjective Vision Questionnaire (SVQ), modified after a pilot trial. Participants were administered the SVQ before clinical evaluation. Items answered by over 95%, with factor loadings > 0.55 were included. Test-retest reliability was assessed by repeat testing. Factor analysis identified groups of questions measuring particular dimensions of data. RESULTS: Sixty-seven items were answered by 128 patients and reduced to 24 items in a final questionnaire. Factor analysis identified six types of questions within the questionnaire, the most important of which was related to driving. CONCLUSION: The simplicity, low cost, and psychometric properties of the Subjective Vision Questionnaire support its use clinically and in research.

Laser in situ keratomileusis with Alcon CustomCornea.

PURPOSE: To report the 3-month results of our first cases of laser in situ keratomileusis (LASIK) with Alcon's CustomCornea. METHODS: Wavefront analysis was performed using the LADARWave aberrometer and ablation was performed with the LADARVision4000 system. Thirty-one eyes of 17 patients were analyzed prospectively, at 1 and 3 months after CustomCornea surgery. Psychophysical tests were performed, including high and low contrast acuity, and contrast sensitivity under scotopic and photopic conditions. In addition, psychometric testing was performed using a subjective vision questionnaire. RESULTS: Mean spherical equivalent refraction improved from a baseline -3.05 +/- 1.92 D to +0.02 +/- 0.28 D at 3 months (28 eyes). At 3 months, 46.4% (13 eyes) had uncorrected visual acuity of 20/16, 92.7% (26 eyes) had 20/20, and 100% (28 eyes) had 20/25 uncorrected visual acuity. Three months after CustomCornea surgery, there was a statistically significant improvement in contrast sensitivity under both scotopic and photopic conditions, and a statistically significant increase in third and fourth order aberrations. There was a statistically significant improvement in visual quality as measured by the subjective vision index, increasing from a preoperative mean 66.62 to 87.63 at 3 months after surgery. CONCLUSIONS: CustomCornea was an improvement over conventional LASIK as measured by most psychophysical and psychometric parameters. The relationship between higher order aberrations and other psychophysical and psychometric measurements needs more analysis.

Conductive keratoplasty to correct residual hyperopia after corneal surgery.

Conductive keratoplasty (CK) is an electrical-current-based technique for steepening the central cornea to reduce low to moderate hyperopia. We report 4 patients who had CK to correct hyperopia after laser in situ keratomileusis (LASIK) and were followed for at least 6 months. An overcorrection was noted after the CK procedure in all patients, but no sight-threatening complications arose. Conductive keratoplasty appears to be safe and well tolerated after LASIK. However, the algorithms should be modified to increase the predictability of the CK procedure in previously treated eyes.

Progressive post-LASIK keratectasia: biomechanical instability or chronic disease process?

Progressive post-LASIK keratectasia (PPLK) is a progressive deformation of corneal anatomy that occurs rarely but may have severe consequences. Using the scientific literature and new hypotheses, we attempted to determine whether PPLK is a biomechanical result of laser in situ keratomileusis (LASIK), a chronic disease process affecting individuals predisposed to the condition, or a combination of processes. We look at whether the combination of fatigue, specifically a form of dynamic fatigue, and proteolysis provides an environment conducive to the occurrence and progression of PPLK. This review may raise more questions than it answers and in so doing may move us toward a better understanding of this occasionally serious consequence of LASIK.

The effect of laser-assisted in situ keratomileusis on retinal nerve fiber layer measurements obtained with scanning laser polarimetry.

PURPOSE: Scanning laser polarimetry provides indirect measurements of retinal nerve fiber layer thickness by measuring the retardation of polarized laser light as it passes through the retinal nerve fiber layer. Laser-assisted in situ keratomileusis is a refractive technique by which corneal stromal photoablation is achieved by the structural and refractive changes induced by the excimer laser. Both techniques are becoming widely performed and there is some evidence that scanning laser polarimetry measurements are significantly changed after laser-assisted in situ keratomileusis. The authors performed a larger study to determine whether laser-assisted in situ keratomileusis induces predictable and consistent alterations in the measurement of retinal nerve fiber layer thickness. METHODS: Retinal nerve fiber layer thickness measurements using scanning laser polarimetry were performed 1 week before and 1 week after laser-assisted in situ keratomileusis in 30 consecutive eyes (16 patients) undergoing the procedure at The Eye Institute. RESULTS: Mean +/- SD preoperative spherical equivalent refraction was -4.66 +/- 2.40 D, mean ablation depth was 73.0 +/- 36.23 microm, and mean patient age was 40.6 +/- 8.7 years. Six of 12 retinal nerve fiber layer thickness measurements showed significant change (P < 0.05) after laser-assisted in situ keratomileusis. There was no correlation with corneal ablation depth (P > 0.05) for all parameters. CONCLUSION: Laser-assisted in situ keratomileusis significantly affects retinal nerve fiber layer thickness measurements obtained by scanning laser polarimetry. Sequential images should be interpreted with caution and new postoperative baseline images should be obtained.

Laser in situ keratomileusis for residual myopia after photorefractive keratectomy.

PURPOSE: To evaluate the efficacy and safety of laser in situ keratomileusis (LASIK) for myopic regression and undercorrection after photorefractive keratectomy (PRK). SETTING: The Eye Institute, Sydney, Australia. METHODS: Fifty eyes of 32 patients were treated by LASIK for residual myopia following primary PRK. The mean spherical equivalent refraction (SEQ) was -2.92 diopters (D) +/- 1.57 (SD) (range -0.75 to -7.88 D). The mean refractive cylinder was 0.96 +/- 0.74 D (range 0 to 3.50 D). For analysis, the eyes were divided into 2 groups: those with 0 or low corneal haze (Group 1) and those with severe corneal haze (Group 2). In Group 1, the SEQ was -1.99 +/- 0.79 D (range -0.75 to -3.75 D) and in Group 2, -3.77 +/- 1.62 D (range -0.75 to -7.90 D). The procedure was performed using the Chiron Automated Corneal Shaper and the Summit Apex Plus laser. The mean interval between PRK and LASIK was 25 months (range 9 to 59 months). The following parameters were studied before and after LASIK retreatment: SEQ, mean refractive cylinder, uncorrected visual acuity (UCVA), and best corrected visual acuity (BCVA). Complications after LASIK retreatment were evaluated. RESULTS: Six months after LASIK, the mean SEQ in all eyes was -0.65 +/- 0.86 D (range +1.50 to -3.35 D); 70.0% of eyes were within +/-1.00 D of emmetropia and the UCVA was 6/12 or better in 72.5%. The mean SEQ in Group 1 was -0.22 +/- 0.55 D (range -0.88 to -1.50 D) and in Group 2, -0.97+/- 0.92 D (range 0.12 to -3.25 D); the UCVA was 6/12 or better in 94.0% of eyes in Group 1 and in 56.0% in Group 2. No statistically significant between-group difference was found in lines of Snellen acuity lost or gained at 6 months. No eye lost more than 1 line of BCVA. CONCLUSIONS: Laser in situ keratomileusis appears to be a safe, effective, and predictable procedure for treating eyes with 0 or low haze with residual myopia after PRK. It is less predictable in eyes with severe haze.

Phakic intraocular lenses.

Since Zaldivar's review of phakic intraocular lenses in these pages in 2000 [1**], further reports of experience with this technology have emerged. Their relative advantages and disadvantages over competing technologies are becoming clearer. Clinical trials, including Food & Drug Administration (FDA) trials, have shown predictability, stability, and efficacy. Safety of these implants over the long term remains a concern, but in some situations, at least, phakic intraocular lenses are becoming the refractive correction of choice. This brief review looks at the most recent data to emerge regarding phakic intraocular lenses.