Association of Treatment Duration and Clinical Outcomes in Dry Eye Treatment with Sutureless Cryopreserved Amniotic Membrane.

Background: While sutureless, cryopreserved amniotic membrane (cAM) has been shown to significantly improve signs and symptoms of dry eye disease (DED), no studies have assessed the association of cAM treatment duration to the differential response in clinical outcomes. Methods: A multi-center, retrospective study was conducted on patients with moderate-to-severe DED who were treated with self-retained cAM (Prokera® Slim) for 2 to 7 days. The primary outcome measure was DEWS severity score assessed at 1 week, 1 month, and 3 months. Secondary outcome measures included ocular discomfort, visual symptoms, corneal staining, and visual acuity. Results: A total of 89 eyes (77 patients) with moderate-to-severe DED (DEWS severity 3.24 ± 0.56) received treatment with self-retained cAM for 2 days (n = 10), 3 days (n = 15), 4 days (n = 12), 5 days (n = 19), 6 days (n = 6), or 7 days (n = 27). DEWS scores significantly improved at 1 week, 1 month, and 3 months for all treatment duration groups, with no significant difference observed between groups at any timepoint. In addition to an improvement in DEWS severity scores, those receiving cAM treatment for 2 days demonstrated a significant improvement in corneal staining, visual symptoms, and ocular discomfort at 1 week, 1 month, and 3 months. Conclusion: This retrospective study suggests that a single placement of self-retained cAM for 2 days can significantly improve signs and symptoms of DED with a lasting benefit observed for up to 3 months.

Objective Quantification of Image Quality and Optical Scatter Before and After Nd:YAG Capsulotomy Using a Double-Pass Technique.

PURPOSE: The purpose of this study is to evaluate and compare the correlation between changes in vision and HD Analyzer dual-pass metrics versus changes in vision and conventional subjective slit lamp gradings in pseudophakic patients with posterior capsular opacity undergoing neodymium:yttrium-aluminum-garnet (Nd:YAG) capsulotomy. PATIENTS AND METHODS: High contrast (HC) and low contrast (LC) best spectacle-corrected distance visual acuity (BCVA) and HD Analyzer evaluation were prospectively performed on patients with mild-to-moderate posterior capsular opacification (PCO) and monofocal and accommodating intraocular lens implants. Differences between pre- and post-operative measurements were calculated, along with the correlation of HD Analyzer metrics and slit lamp grading to changes in visual acuity. RESULTS: Following Nd:YAG capsulotomy (n=29), there was statistically significant improvement in HC-BCVA and LC-BCVA, decrease in optical scatter, and corresponding improvement in Strehl ratio and HD Analyzer values at all contrast levels tested (p≤0.05). Pearson test showed a high correlation between the improvement in HC-BCVA (r coefficient = 0.78) and LC-BCVA (r coefficient = 0.71) to the improvement in Objective Scatter Index (OSI). There was a higher correlation of change in HC-BCVA to pre-op OSI  (r2=0.61) than to the subjective PCO grading score (r2 = 0.19). There was also a higher correlation of change in LC-BCVA to pre-op OSI (r2 = 0.49) than to subjective grading (r2 = 0.16). CONCLUSION: The HD Analyzer provides objective measurements of forward light scatter (ie, light directed towards the retina) that can assist with both PCO grading and prediction of improvement of visual quality after YAG laser capsulotomy with higher accuracy than conventional slit lamp assessment based upon backscatter (ie, light traveling to the observer) in patients tested with monofocal and accommodating intraocular lens implants.

The Influence of Tomographic Corneal Characteristics on Epithelial Thickness Profile.

Purpose To understand the influence of tomographic corneal characteristics on the epithelium of normal eyes. Methods We scanned a total of 98 eyes of 98 individuals using anterior segment tomography and a spectral-domain optical coherence tomography (OCT) epithelial mapping tool. Only eyes with no previous pathology were included, with a refractive range of +5 diopters (D) to -6 D, intraocular pressure of < 22 mmHg, and no evidence of dry eye (Schirmer's test 2 value > 5 mm). Corneal curvature metrics were statistically correlated with regional epithelial thickness parameters. Results The anterior and posterior corneal surface flat and steep axis, the maximum and minimum curvature, corneal topographic astigmatism, astigmatism polar values, and corneal volume had no statistically significant correlation (p>0.05) with the epithelial thickness. Similarly, anterior corneal surface asphericity had no significant correlation. Posterior surface asphericity had a statistically significant moderate correlation with the epithelium in all areas. Similar results were seen in the multivariate analysis. Conclusions None of the front or back surface parameters had any influence on the corneal epithelium except for the posterior surface asphericity. This statistically significant yet clinically insignificant correlation may be enhanced in diseased populations like keratoconus and could indicate epithelial remodeling with early posterior corneal changes.

Longitudinal changes in dry eye symptoms and signs following lifitegrast therapy and relationship to tear osmolarity.

BACKGROUND: This study measured longitudinal changes in dry eye disease (DED) symptoms and signs following lifitegrast therapy and assessed their relationship to tear osmolarity to test the hypothesis that a decline in tear osmolarity is a reliable leading indicator of subsequent improvement in DED symptoms and signs after initiating lifitegrast treatment. METHODS: This phase IV, prospective, single-arm, open-label, 12-week study enrolled subjects aged ≥18 years with eye dryness score ≥40 (0-100 VAS) and tear osmolarity ≥308 mOsm/L. Subjects were prescribed lifitegrast ophthalmic solution 5%, twice daily in each eye. DED symptoms were assessed via VAS at baseline and 2, 6, and 12 weeks. Signs included tear osmolarity, meibomian gland dysfunction, tear breakup time, and fluorescein corneal staining. In post-hoc analysis, subjects with ≥5 mOsm/L decrease in osmolarity over 12 weeks were Responders. RESULTS: Of 26 subjects in the intent-to-treat population, 23 were female; mean age was 67.4 years. Baseline mean±SD eye dryness was 68.7±16.5 and tear osmolarity was 317.8±8.5 mOsm/L. All seven symptoms (dryness, burning, foreign body sensation, pain, photophobia, itching, blurred vision) declined significantly (P<0.01) from baseline to 6 and 12 weeks. Signs did not change significantly. For 13 Responders, tear osmolarity decreased from baseline to 12 weeks (319.2±8.5 to 300.6±12.3 mOsm/L, P<0.001) and corneal staining trended toward improvement (1.1±0.9 to 0.6±0.7, P=0.136). Among Nonresponders, osmolarity increased from 316.4+8.7 to 329.6+13.9 (P<0.01) and corneal staining showed no change (1.3±0.8 to 1.0±0.7 at 12 weeks, P=0.293). CONCLUSIONS: Lifitegrast reduced DED symptoms among subjects with moderate-to-severe disease (severity defined by VAS for eye dryness). Potential reasons that may underlie the dichotomous effect of drug treatment on tear osmolarity are discussed.

Treatment outcomes in the DRy Eye Amniotic Membrane (DREAM) study.

PURPOSE: To evaluate the efficacy of cryopreserved amniotic membrane (CAM) in reducing signs and symptoms of dry eye disease (DED) in a large patient population. METHODS: A retrospective chart review at 10 clinical sites was done of patients with refractory DED who received CAM and completed at least 3 months of follow-up. Data collected were demographics; medical history including previous and current ocular treatment, diagnosis, clinical presentations, comorbidity, duration and frequency of treatment with CAM; and concomitant medications. The primary outcome was the change in dry eye workshop (DEWS) score after treatment. RESULTS: A total of 97 eyes of 84 patients exhibited severe dry eye despite maximal medical treatments including topical artificial tears, cyclosporine-A, serum, antibiotics, and steroids. Patients manifested with superficial punctate keratitis (86%), filamentary keratitis (13%), exposure keratitis (19%), neurotrophic keratitis (2%), and corneal epithelial defect (7%). After CAM treatment for 5.4±2.8 days, 74 (88%) patients demonstrated an improved ocular surface along with a notable reduction of the severity as the overall DEWS score was significantly reduced from 3.25±0.5 at baseline to 1.44±0.6 at 1 week, 1.45±0.6 at 1 month, and 1.47±0.6 at 3 months (p<0.001). Ten eyes (10%) required repeated treatment to complete healing. Apart from discomfort during CAM placement, there were no adverse events. CONCLUSION: Placement of CAM is promising to enhance the recovery of ocular surface health and reduce signs and symptoms in patients with moderate-to-severe DED.

Benefits and barriers of accommodating intraocular lenses.

PURPOSE OF REVIEW: Presbyopia and cataract development are changes that ubiquitously affect the aging population. Considerable effort has been made in the development of intraocular lenses (IOLs) that allow correction of presbyopia postoperatively. The purpose of this review is to examine the benefits and barriers of accommodating IOLs, with a focus on emerging technologies. RECENT FINDINGS: True accommodation of an IOL involves a dynamic increase in dioptric power to affect a shift from distance to intermediate or near focus. The Crystalens (Crystalens Bausch and Lomb, Inc., Rochester, NY, USA) was the first IOL labeled by the FDA as an accommodating IOL. Further studies have suggested that the Crystalens and several other single optic presbyopia-correcting IOLs may be providing improved intermediate or near vision predominantly through pseudoaccommodative mechanisms, in addition to small changes in axial translation. In light of these findings, a more objective demonstration of accommodation is now required for an IOL to have an accommodative label. Newer technology accommodating IOLs in development have embraced design strategies using dual optics, shape-changing optics, and IOLs with dynamic changes in refractive index. Prevention and treatment algorithms for capsular contraction syndromes unique to Crystalens and Trulign IOL designs will be discussed. SUMMARY: Accommodating IOLs that are in current use are constrained by their low and varied amplitude of accommodation. Such limitations may be circumvented in the future by accommodative design strategies that rely more on shape-related changes in the surfaces of the IOLs or in dynamic changes in refractive index than by forward translation alone.

A prospective randomized clinical evaluation of 3 presbyopia-correcting intraocular lenses after cataract extraction.

PURPOSE: To compare contrast sensitivity, visual acuity (VA), and halos in subjects bilaterally implanted with 1 of 3 FDA-approved presbyopia-correcting intraocular lenses. DESIGN: Prospective, randomized, partially masked, multicenter clinical trial. METHODS: Seventy-eight subjects were randomized sequentially for bilateral implantation with the Crystalens AO (Bausch & Lomb Surgical), AcrySof IQ ReSTOR +3.0 (Alcon Laboratories), or Tecnis Multifocal (Abbott Medical Optics) lenses. Subjects were evaluated through visit 4 (4 to 6 months after surgery) with the following monocular and binocular assessments: high- and low-contrast VA, contrast sensitivity without glare, halos or starbursts, defocus curves, optical scatter, retinal point spread function, and safety. RESULTS: The Crystalens AO and ReSTOR +3.0 demonstrated better monocular and binocular contrast sensitivity without glare at low to mid spatial frequencies compared with the Tecnis Multifocal lens. Binocular uncorrected distance VA was not significantly different between the 3 lenses. The Crystalens AO had significantly better binocular low-contrast distance-corrected VA than the ReSTOR +3.0 and better mean monocular low-contrast DCVA than the Tecnis Multifocal lens. The Crystalens AO demonstrated significantly better monocular and binocular uncorrected and distance-corrected intermediate VA than the ReSTOR +3.0 or Tecnis Multifocal lenses. The ReSTOR+3.0 lens had significantly better monocular and binocular uncorrected and distance-corrected near VA tested at 40 cm compared with the Crystalens AO and Tecnis Multifocal lens. The Crystalens AO elicited significantly less halos than the Tecnis Multifocal lens and less optical scatter than the ReSTOR +3.0 or Tecnis Multifocal lens. CONCLUSIONS: The Crystalens AO had statistically better uncorrected intermediate VA and distance-corrected intermediate VA than the ReSTOR +3.0 or Tecnis Multifocal lenses and fewer photic phenomenon than the Tecnis Multifocal lens. Both multifocals had better distance-corrected near VA and uncorrected near VA than the Crystalens AO. These findings may guide intraocular lens selection for individual patients seeking to optimize vision at specific vergences or lighting conditions.

Postoperative changes in intraocular pressure and corneal biomechanical metrics Laser in situ keratomileusis versus laser-assisted subepithelial keratectomy.

PURPOSE: To compare intraocular pressure (IOP) and corneal biomechanical metric changes after myopic laser in situ keratomileusis and laser-assisted subepithelial keratectomy (LASEK). SETTING: Private practice, St. Louis, Missouri, USA. METHODS: The IOP, corneal biomechanical markers, and Ocular Response Analyzer (ORA) waveform parameters were prospectively measured preoperatively and after 6 months in ablation-matched myopic LASIK eyes (mLASIK group) and LASEK eyes (mLASEK group). A retrospectively identified cohort of low myopia LASIK eyes (lmLASIK group) and fellow unoperated eyes (control) were tested at a single postoperative visit. Statistical analysis compared the percentage change in parameters between groups. RESULTS: The mean postoperative Goldmann tonometry and Goldmann-correlated IOPs were statistically significant reduced in the mLASIK and mLASEK groups (P<.03). Corneal-compensated IOP, but not Pascal dynamic contour tonometry, was significantly reduced in the mLASIK group. The percentage change in corneal hysteresis (CH) and the corneal resistance factor (CRF) was greater in the mLASIK and mLASEK groups than in the lmLASIK group. The greatest percentage change in ORA signal parameters was in the mLASIK group and the smallest change, in the mLASEK group. On multivariate linear regression, the residual stromal bed was predictive of the percentage change in CH and CRF (P<.001). CONCLUSIONS: Microkeratome flap creation combined with deeper stromal ablation had the greatest effect on the ORA applanation signal, indicating corneas that are more readily deformable. The smallest change in the signal was in the group without a stromal flap (LASEK). There was a complex interaction between ablation location and depth that affected corneal biomechanical properties.

Novel objective method for comparing ablation centration with and without pupil tracking following myopic laser in situ keratomileusis using the bausch & lomb technolas 217A.

PURPOSE: To apply an objective method to topographically determine functional optical zone (TFOZ) dimensions in order to compare ablation centration, and refractive outcomes, following myopic laser in situ keratomileusis (LASIK) with and without automated, infrared (IR) pupil tracking. METHODS: Thirty-seven eyes that underwent LASIK using the Technolas 217A with active IR pupil tracking (IT) were retrospectively compared to 37 matched eyes treated with manual tracking (MT). Visual acuity, refractive error, and corneal topography were measured pre- and postoperatively. Videokeratography and specialized software were used to assess centration. RESULTS: The IR-tracked eyes had statistically better mean postoperative spherical equivalent (IT +0.02 +/- 0.38 D; MT -0.21 +/- 0.48 D; P = 0.03) and uncorrected distance visual acuity (IT +0.07 +/- 0.08 logMAR; MT +0.02 +/- 0.09 logMAR; P = 0.02). One versus three eyes lost 1 line of best spectacle-corrected visual acuity in the IT and MT groups, respectively. While similar mean displacement of the TFOZ center from the pupil center was found in the MT (0.54 +/- 0.27 mm) and IT (0.51 +/- 0.21 mm) groups (P = 0.77), 4 MT eyes (10.8%) were topographically decentered >1.0 mm, whereas the ablation center was within 1 mm of the pupil center for all IT eyes. CONCLUSIONS: Custom software provided a novel, objective method to determine topographic functional optical zone dimensions, then mathematically calculate the center of the optical zone relative to the pupil center and measure the vector of decentration. Use of IR pupil tracking improved uncorrected visual acuity, produced more predictive refractive outcomes, and fewer large centration outliers. This may reflect increased fidelity of spot placement to the attempted ablation profile.

Comparison of contrast sensitivity, depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration.

PURPOSE: To compare the clinical performance of the zero spherical aberration (SA) SofPort LI61AO (AO, Bausch & Lomb) intraocular lens (IOL) to the AcrySof SA60AT (AT, Alcon), which has positive spherical aberration. METHODS: Patients underwent uneventful phacoemulsification with implantation of either an aspheric (AO, n = 19) or spherical (AT, n = 20) IOL. Postoperatively, a 5 mm artificial pupil was positioned in trial frames with the cycloplegic refraction during monocular, mesopic contrast sensitivity (CSF) and low-contrast visual acuity (LCVA) testing with glare. Ocular and corneal wavefront error was determined at 5 mm diameters. RESULTS: Mean CSF scores were better at all frequencies tested for the AO than for the AT group, and achieved statistical significance at 1.5 cpd (p = 0.038) and 6 cpd (p = 0.017). With glare, AO eyes read 30.9 +/- 5.0 low-contrast letters versus 25.2 +/- 6.8 for AT eyes (p = 0.005) (mean DeltaLogMAR = -0.10), while high-contrast acuity and refraction were similar. Eyes implanted with the SA60AT had 43% greater positive spherical aberration at a 5 mm wavefront diameter, with no significant difference in corneal SA between groups. A through-focus analysis demonstrated a similar depth of field, yet a comparatively higher visual Strehl ratio for the aspheric IOL at emmetropia (p = 0.038). CONCLUSION: Eyes with the SofPort Advance Optics neutral aberration IOL demonstrated less spherical aberration and better low-contrast acuity compared to eyes with a spherical IOL, without sacrificing tolerance to defocus. The aspheric IOL showed superior optical and clinical performance, which is most likely due to its surface design.

Biometry and intraocular lens power calculation.

PURPOSE OF REVIEW: Heightened patient expectations for precise postoperative refractive results have spurred the continued improvements in biometry and intraocular lens calculations. In order to meet these expectations, attention to proper patient selection, accurate keratometry and biometry, and appropriate intraocular lens power formula selection with optimized lens constants are required. The article reviews recent studies and advances in the field of biometry and intraocular lens power calculations. RECENT FINDINGS: Several noncontact optical-based devices compare favorably, if not superiorly, to older ultrasonic biometric and keratometric techniques. With additional improvements in the internal acquisition algorithm, the new IOL Master software version 5 upgrade should lessen operator variability and further enhance signal acquisition. The modern Haigis-L and Holladay 2 formulas more accurately determine the position and the shape of the intraocular lens power prediction curve. SUMMARY: Postoperative refractive results depend on the precision of multiple factors and measurements. The element with the highest variability and inaccuracy is, ultimately, going to determine the outcome. By understanding the advantages and limitations of the current technology, it is possible to consistently achieve highly accurate results.

Visual performance of patients with bilateral vs combination Crystalens, ReZoom, and ReSTOR intraocular lens implants.

PURPOSE: To compare the visual performance of patients with bilateral vs combination Crystalens, ReZoom, and ReSTOR intraocular lens (IOLs) implants. DESIGN: Prospective, nonrandomized study. METHODS: Forty-nine patients were implanted with bilateral Crystalens (Eyeonics, Aliso Viejo, California, USA), ReSTOR (Alcon Laboratories, Fort Worth, Texas, USA), and ReZoom (American Medical Optics, Santa Clara, California, USA) or combined Crystalens and ReSTOR or Crystalens and ReZoom IOLs after phacoemulsification. Monocular and binocular testing four to six months after surgery included uncorrected and best-spectacle corrected visual acuity at distance, intermediate, and near vision; mesopic contrast sensitivity function with and without glare; and quality-of-life and vision surveys six months after surgery. RESULTS: Monocular testing showed that eyes with Crystalens accommodating IOL had statistically better best-spectacle corrected distance, uncorrected and distance-corrected intermediate, and best-corrected near vision. Eyes with the ReSTOR multifocal IOL had better uncorrected near vision, required the lowest reading add, and had the lowest uncorrected and distance-corrected intermediate vision. Monocular mesopic contrast sensitivity with and without glare was better with the Crystalens IOL vs either multifocal IOL at specific spatial frequencies. The binocular subjective quality of vision and quality of life questionnaires were favorable for the bilateral Crystalens group. CONCLUSIONS: Any combination of Crystalens in one or both eyes was better for intermediate vision. Any combination of ReSTOR in one or both eyes was better for near vision. The Crystalens and ReSTOR combination had better mean intermediate and near vision overall. A multifocal IOL in one or both eyes was associated with lower contrast sensitivity and more subjective reports of photic phenomena. The accommodating and multifocal IOL combinations elicited less night glare symptoms than in patients with either bilateral multifocal IOL, but more than with bilateral Crystalens implantation.

Comparative performance of the Zyoptix XP and Hansatome zero-compression microkeratomes.

PURPOSE: To compare flap parameters produced by the Zyoptix XP and Hansatome microkeratomes (both Bausch & Lomb) and to evaluate preoperative variables contributing to flap thickness variation. SETTING: Private practice, St. Louis, Missouri, USA. METHODS: Flap dimensions in 75 eyes that prospectively had laser in situ keratomileusis using the Zyoptix XP microkeratome were compared with a historical control sample of 75 eyes treated with the Hansatome microkeratome. The 2 groups were matched for mean keratometry, central corneal pachymetry, spherical equivalent (SE), age, and microkeratome head size and suction ring diameter. RESULTS: The mean ultrasound-measured flap thickness was 126.54 microm +/- 14.6 (SD) and 143.74 +/- 15.0 microm for the 120 microm and 140 microm Zyoptix XP heads, respectively, and 128.90 +/- 20.4 microm and 143.32 +/- 21.0 microm for the 160 microm and 180 microm Hansatome heads, respectively. The standard deviation in flap thickness was smaller and statistically significant for the Zyoptix XP (+/-14.8 microm) versus the Hansatome (+/-20.7 microm) (P = .0039, F test). Preoperative pachymetry and SE (P<.001) accounted for 20% of the variability in measured flap thickness using the Hansatome. For the Zyoptix XP, preoperative pachymetry was statistically significant in explaining the variation in flap thickness with the 120 microm head (P = .02) but not with the 140 microm head. Variation in flap thickness from either Zyoptix XP head was not statistically related to the preoperative SE. CONCLUSION: Although the 2 microkeratomes produced flaps of similar mean thickness, the Zyoptix XP showed significantly less variation in flap thickness than the Hansatome, was less affected by measurable preoperative variables such as SE, and was closer to nominal labeling.

Determining corneal power using Orbscan II videokeratography for intraocular lens calculation after excimer laser surgery for myopia.

PURPOSE: To assess the accuracy of Orbscan II slit-scanning videokeratography for intraocular lens (IOL) calculation in eyes with previous photorefractive surgery for myopia. SETTING: Private practice, St. Louis, Missouri, USA. METHODS: Corneal power (K) was measured by manual keratometry, Placido-based videokeratography (Atlas), slit-scanning videokeratography (Orbscan II), and contact lens overrefraction in 21 post-photoablation eyes having cataract surgery. Postoperative data collected after phacoemulsification were used to back-calculate corneal power (BCK). The BCK values were statistically compared at 3.0 to 6.0 mm central Orbscan II curvature and power measurements, including total axial power, total tangential power, total mean power, and total optical power. Similar comparisons were made to Atlas curvature at the 0.0 to 10.0 mm zones. RESULTS: The mean corneal power after refractive surgery based on BCK values using the Holladay 2 formula (BCK H2) was 39.35 diopters (D) +/- 2.58 (SD). The mean manual value (40.52 +/- 1.95 D) and Atlas-based values were statistically higher than BCK H2 values (P<.001). The mean corneal power calculated from historical data was 39.33 +/- 2.70 D (P = .83 to BCK H2; n = 19) and from contact lens overrefraction, 41.38 +/- 3.11 D (P = .19; n = 5). Orbscan II parameters (n = 21) of the total mean power (3.0 mm, 39.10 +/- 2.63 D), total tangential power (3.0 mm, 39.11 +/- 2.60), total axial power (5.0 mm, 39.19 +/- 2.55 D), and total optical power (3.0 mm, 39.08 +/- 2.78 D; 4.0 mm, 39.39 +/- 2.76 D) were statistically similar to both the historical and BCK H2 values (P>.11). If used prospectively, 80.9% of eyes would have been within +/-0.50 D of the targeted refraction using a 4.0 mm total optical power, 76.2% using a 5.0 mm total axial power, and 42.1% using the historical method. CONCLUSION: The Orbscan II 5.0 mm total axial power and 4.0 mm total optical power can be used to more accurately predict true corneal power than the history-based method and may be particularly useful when pre-LASIK data are unavailable.

Changes in corneal biomechanics and intraocular pressure following LASIK using static, dynamic, and noncontact tonometry.

PURPOSE: To compare the preoperative and postoperative measurement of corneal biomechanical properties and intraocular pressure (IOP) using Goldmann applanation tonometry (GAT), the ocular response analyzer (ORA), and the Pascal dynamic contour tonometer (PDCT) in eyes undergoing myopic laser in situ keratomileusis (LASIK). DESIGN: Prospective, nonrandomized clinical trial. METHODS: IOP was measured in 66 myopic eyes before and after LASIK by GAT, ORA, and PDCT in a randomized sequence. Metrics of corneal biomechanical properties (corneal hysteresis [CH], corneal resistance factor [CRF], and ocular pulse amplitude [OPA]) were recorded. RESULTS: After LASIK, there was a reduction in mean corneal pachymetry of 90.2 mum and in IOP measurements with GAT (Delta = -1.8 +/- 2.8 mm Hg; P < .01), ORA-Goldmann (Delta = -4.6 +/- 2.8 mm Hg, P < .01), and ORA-corneal compensated (Delta - 2.1 +/- 2.6 mm Hg; P < .05). However, there was no statistically significant difference between preoperative and postoperative IOP measurements taken by PDCT (Delta = -0.5 +/- 2.6 mm Hg). Postoperatively, CRF decreased by 28.6% (P < .01), CH by 16.2% (P < .01), and OPA by 1.8% (P = .32). CONCLUSIONS: Measurement of IOP with PDCT appears to be relatively immune to changes in corneal biomechanics and pachymetry after LASIK, in comparison to GAT and ORA measures of IOP. PDCT and ORA both showed statistically lower variation in measurement than GAT. LASIK produced a marked decline in CH and CRF, which may reflect respective changes in the viscous and elastic qualities of the post-LASIK cornea. In contrast, there was no statistical change in OPA.

Development of late-onset subepithelial corneal haze after laser-assisted subepithelial keratectomy with prophylactic intraoperative mitomycin-C Case report and literature review.

We present a case of dense, visually significant reticular haze that developed approximately 17 months after uneventful laser-assisted subepithelial keratectomy with mitomycin-C (MMC). The patient was successfully treated with manual debridement coupled with phototherapeutic keratectomy and intraoperative MMC.

Topographic and biomechanical differences between hyperopic and myopic laser in situ keratomileusis.

PURPOSE: To evaluate the size, shape, and uniformity of the videokeratographic functional optical zone (FOZ) after laser in situ keratomileusis (LASIK) in 2 cohorts of patients with equivalent amounts of preoperative myopic or hyperopic astigmatism. SETTING: Pepose Vision Institute, St. Louis, Missouri, USA. METHODS: Eyes with myopic or hyperopic astigmatism (n=27 in each group) that had LASIK with the Visx Star S3 laser were retrospectively selected to match for level of preoperative refractive error. Slit-scanning videokeratography was performed preoperatively and 6 months postoperatively and analyzed using custom software. The FOZ was calculated by analyzing refractive power maps using a region-growing algorithm. Difference maps were generated from slit images and compared for interval change in corneal elevation, tangential curvature, and refractive power. The difference maps were also averaged (mean difference maps) for each target population. A Zernike decomposition of corneal first-surface elevation was performed to compare postoperative values with baseline parameters. RESULTS: The mean postoperative refractive sphere at 6 months was -0.17 diopter (D) +/- 0.66 (SD) and +0.25 +/- 0.85 D in the myopia group and hyperopia group, respectively, and the mean postoperative astigmatism, -0.49 +/- 0.32 D and -0.65 +/- 0.52 D, respectively (P=.11). Based on the refractive power maps, the mean preoperative and postoperative myopic FOZ was 33.09 +/- 7.30 mm(2) and 30.94 +/- 5.43 mm(2), respectively, and the mean hyperopic FOZ, 33.19 +/- 7.96 mm(2) and 37.99 +/- 6.88 mm(2), respectively. After LASIK, there was an increase in magnitude of negative anterior corneal surface spherical-like Zernike values in the myopia group (P<.0001) and an increase in magnitude of positive spherical-like Zernike values in the hyperopia group. Postoperatively, significant induction of corneal surface horizontal coma was noted in hyperopic eyes (P<.0001). Hyperopic eyes, on average, had larger topographic FOZs after LASIK, but with less uniformity of curvature and power change than myopic eyes. CONCLUSIONS: Hyperopic LASIK, which involves more transition points along the ablation diameter, produced a less uniform topographic FOZ than typical myopic treatments. Less predictable biomechanical changes from the circumferential release of tension on collagen bundles after midperipheral hyperopic ablation and greater variation in beam centration and the angle of incidence may contribute to the greater variability in corneal curvature and power in hyperopic LASIK than in myopic LASIK.

Treatment of dense subepithelial corneal haze after laser-assisted subepithelial keratectomy.

We report a case of dense and visually significant corneal haze after laser-assisted subepithelial keratectomy (LASEK). Visually significant corneal haze after LASEK can be successfully treated with manual debridement and intraoperative mitomycin-C.

The effect of punctal occlusion on wavefront aberrations in dry eye patients after laser in situ keratomileusis.

PURPOSE: To compare the wavefront aberrations in post-laser in situ keratomileusis (LASIK) dry eye patients before and after punctal occlusion. DESIGN: Prospective, comparative, nonrandomized study. METHODS: Wavefront aberrometry was performed on 16 eyes of eight patients with dry eyes after LASIK surgery. Wavefront measurements were taken before and 1 month after punctal plug placement and compared with 10 eyes of post-LASIK patients without clinically dry eyes measured twice 1 month apart. Student t tests were used to assess the statistical significance of differences between pre- and post-punctal plug measurements. RESULTS: Punctal occlusion in the post-LASIK dry eye patients significantly reduced total, lower, and higher order wavefront aberrations by 47% to 63% (P <.01). Among higher-order aberrations, there were significant reductions in coma and spherical aberration but not in trefoil, after punctal occlusion. The reduction of wavefront aberrations by punctal occlusion in post-LASIK dry eye patients resulted in a significant improvement in quantitative visual acuity assessed using an Early Treatment of Diabetic Retinopathy Study chart and in subjective qualitative vision, confirmed by convolutional analysis using image simulation. No statistically significant differences in any of these metrics were found in the post-LASIK control group without clinically dry eyes measured twice at a similar time interval. CONCLUSIONS: Wavefront aberrometry provides a useful, objective assessment of post-LASIK dry eye patients before and after punctal plug placement. Aggressive treatment of dry eyes may be important before obtaining wavefront measurements that serve as the basis for planning refractive corneal laser treatments and retreatments.

Intraocular lens calculations in patients with corneal scarring and irregular astigmatism.

PURPOSE: To compare various methods of estimating corneal power for intraocular lens (IOL) calculation in patients with irregular corneal astigmatism. SETTING: Pepose Vision Institute, St. Louis, Missouri, USA. Case reports and review of the medical literature. RESULTS: Two patients with irregular corneal astigmatism had an IOL exchange after a "surprise" post-cataract-surgery refraction. In the first case, the patient had a post-cataract-surgery refraction of +5.50 -0.75 x 69 and in the second case, a refraction of -7.00 -1.00 x 180. The central corneal power before IOL exchange was assessed using manual keratometry, various computerized videokeratography curvature and power maps, and contact lens overrefraction. The total axial power map (Orbscan(R), Bausch & Lomb), total optical power map (Orbscan), and contact lens overrefraction method provided the most accurate estimates of central corneal power in these 2 patients. CONCLUSION: Computerized scanning-slit videokeratography, which analyzes the anterior and posterior surfaces of the cornea, and the contact lens overrefraction method gave good estimations of corneal power in patients with irregular corneal astigmatism. This type of analysis may improve the accuracy of IOL calculation in patients with corneal pathology and irregular astigmatism.