Richard Potvin

Effects of preoperative corneal astigmatism orientation on results with a low-cylinder-power toric intraocular lens

PURPOSE: To evaluate refractive results with a low‐cylinder‐power toric intraocular lens (IOL) and the effect of preoperative corneal astigmatism orientation on results. SETTING: Private practice, Jackson, Michigan, USA. DESIGN: Comparative case series. METHODS: This retrospective review of clinical records comprised patients with 0.75 to 1.38 diopters (D) of preoperative corneal astigmatism who had uneventful cataract surgery and AcrySof T3 toric or AcrySof IQ spherical monofocal IOL implantation. Surgically induced astigmatism (SIA) was calculated for eyes with postoperative keratometry results. Postoperative refractive astigmatism between groups and subgroups was compared based on the orientation of preoperative corneal astigmatism. RESULTS: Of the eyes, 185 had a toric IOL and 138 had a spherical IOL. The mean preoperative corneal astigmatism was 1.06 D, with no significant difference between IOL groups or by axis of astigmatism. The mean SIA was 0.25 D, with no significant difference between IOL groups. The mean postoperative refractive astigmatism was statistically significantly lower in the toric IOL group than in the spherical IOL group (0.31 D versus 1.06 D; P<.001). The axis of preoperative corneal astigmatism was not a significant factor in the toric IOL group. In the spherical IOL group, the residual astigmatism was slightly higher for with‐the‐rule than for against‐the‐rule astigmatism (1.07 D versus 0.70 D; P<.001). CONCLUSIONS: The mean refractive astigmatism after cataract surgery in patients with 0.75 D to 1.38 D of corneal astigmatism was significantly lower when a toric IOL was implanted. Postoperative refractive astigmatism with the toric IOL was independent of preoperative corneal astigmatism axis orientation. Financial Disclosure: Neither author has a financial or proprietary interest in any material or method mentioned.

Comparative visual performance with monofocal and multifocal intraocular lenses

Background To compare near, intermediate, and distance vision, and quality of vision using appropriate subjective questionnaires, when monofocal or apodized diffractive multifocal intraocular lenses (IOLs) are binocularly implanted. Methods Patients with different binocular IOLs implanted were recruited after surgery and had their visual acuity tested, and quality of vision evaluated, at a single diagnostic visit between 3 and 8 months after second-eye surgery. Lenses tested included an aspheric monofocal and two apodized diffractive multifocal IOLs with slightly different design parameters. A total of 94 patients were evaluated. Results Subjects with the ReSTOR® +2.5 D IOL had better near and intermediate vision than those subjects with a monofocal IOL. Intermediate vision was similar to, and near vision slightly lower than, that of subjects with a ReSTOR® +3.0 D IOL implanted. The preferred reading distance was slightly farther out for the +2.5 D relative to the +3.0 D lens, and farthest for the monofocal. Visual acuity at the preferred reading distance was equal with the two multifocal IOLs and significantly worse with the monofocal IOL. Quality of vision measures were highest with the monofocal IOL and similar between the two multifocal IOLs. Conclusion The data indicate that the ReSTOR +2.5 D IOL provided good intermediate and functional near vision for patients who did not want to accept a higher potential for visual disturbances associated with the ReSTOR +3.0 D IOL, but wanted more near vision than a monofocal IOL generally provides. Quality of vision was not significantly different between the multifocal IOLs, but patient self-selection for each lens type may have been a factor.

Absence of keratectasia after LASIK in eyes with preoperative central corneal thickness of 450 to 500 microns.

PURPOSE To determine whether preoperative central corneal thickness less than or equal to 500 microm is an independent risk factor for development of keratectasia following LASIK. METHODS Chart review was performed for 109 eyes with preoperative central corneal thickness of 452 to 500 microm in 69 patients who underwent LASIK between September 2000 and July 2005 and had no known risk factors for keratectasia. All eyes included in this analysis had postoperative manifest refractions at follow-up at 1-month and 12-months or greater (median: 452 days; range: 365 to 1980 days). RESULTS Attempted correction (spherical equivalent refraction) ranged from +3.13 to -7.75 diopters. There were no clinical signs of keratectasia at any postoperative visits in the 109 eyes in this study. There was no statistically significant change in mean spherical equivalent or manifest cylinder from the 1-month follow-up examination to the last documented visit (12 months or greater). No correlation was found for preoperative pachymetry and refractive change between postoperative examinations at 1 month and 12 months or greater. Double-angle vector analysis determined the directional shift in postoperative refractive cylinder was not statistically significant from zero (P > .05). CONCLUSIONS In this group of 109 LASIK-treated eyes with preoperative central corneal thickness less than or equal to 500 microm that were screened for known keratectasia risk factors, there was no evidence of postoperative keratectasia.

Modern laser in situ keratomileusis outcomes

UNLABELLED Laser in situ keratomileusis (LASIK) articles published between 2008 and 2015 that contain clinical outcomes data were reviewed and graded for quality, impression, and potential bias. All 97 relevant articles (representing 67 893 eyes) provided a positive or neutral impression of LASIK. Industry bias was not evident. The aggregate loss of 2 or more lines of corrected distance visual acuity was 0.61% (359/58 653). The overall percentage of eyes with uncorrected distance visual acuity better than 20/40 was 99.5% (59 503/59 825). The spherical equivalent refraction was within ±1.0 diopter (D) of the target refraction in 98.6% (59 476/60 329) of eyes, with 90.9% (59 954/65 974) within ±0.5 D. In studies reporting patient satisfaction, 1.2% (129/9726) of patients were dissatisfied with LASIK. Aggregate outcomes appear better than those reported in summaries of the safety and effectiveness of earlier laser refractive surgery systems approved by the U.S. Food and Drug Administration. Modern results support the safety, efficacy, and patient satisfaction of the procedure. FINANCIAL DISCLOSURE Proprietary or commercial disclosures are listed after the references.

Prospective Multicenter Study of Toric IOL Outcomes When Dual Zone Automated Keratometry Is Used for Astigmatism Planning

PURPOSE To evaluate clinical outcomes when toric intraocular lens (IOL) calculations are based on the keratometric output from the Lenstar LS-900 dual zone automated keratometer (Haag-Streit AG, Koeniz, Switzerland). METHODS Eligible subjects presenting for toric IOL implantation at five sites were measured with a dual-zone automated keratometer. The data were used to plan the power and angle of the toric IOL to be implanted. Refractive and visual acuity status were checked at 1 and 3 months postoperatively. RESULTS A total of 102 eyes had relevant data for analysis. More than 76% of eyes had 0.50 diopter or less of refractive astigmatism at 1 and 3 months, with no difference by level of astigmatism corrected. More than half of the eyes had uncorrected distance visual acuity of 20/20 or better and 78% were 20/25 or better. A new measure of effectiveness of toric correction power is described that suggested lens selection was appropriate. Results appeared better than those obtained in previous studies when the IOL cylinder power and alignment were calculated using manual keratometry. CONCLUSIONS In this series of eyes from multiple centers, the calculation of toric IOL power using dual-zone automated keratometry measurements produced clinical results that were better than results in the literature where manual keratometry was used.

Simulation of toric intraocular lens results: Manual keratometry versus dual-zone automated keratometry from an integrated biometer

PURPOSE: To evaluate simulated clinical outcomes in patients with toric intraocular lenses (IOLs) calculated on the basis of dual‐zone automated keratometry from an integrated optical biometer, relative to manual keratometry. SETTING: Private practice, Mesa, Arizona, USA. DESIGN: Comparative case series. METHODS: Patient records at 4 clinical sites were reviewed to identify patients who had manual keratometry and biometry with the Lenstar LS 900 recorded before toric IOL implantation and refractive follow‐up data after implantation. Preoperative and operative data were extracted from patient charts. Simulated refractive outcomes were calculated based on mathematically removing the actual IOL implanted and then mathematically inserting the IOLs as determined by manual or automated keratometry from the biometry device. RESULTS: Data for 128 patients were available for analysis. The actual residual astigmatism was comparable between manual keratometry and automated keratometry from the biometry system. Although simulated residual refractive astigmatism was similar between the 2 devices on average, there was variability in results by patient. Simulated residual refractive astigmatism was lower for the biometer when the standard deviation of the angle of astigmatism was low. Site‐to‐site variability was lower with the biometer than with manual keratometry. CONCLUSIONS: Simulated outcomes suggest that overall results for a group of patients whose toric IOL surgery planning is performed with the dual‐zone automated keratometry data from the biometer will be equivalent to those when manual keratometry is used. The reduced site‐to‐site variability with the biometer suggests an operational advantage. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

New algorithm for post-radial keratotomy intraocular lens power calculations based on rotating Scheimpflug camera data

Purpose To provide an algorithm to calculate intraocular lens (IOL) power for post‐radial keratometry (RK) eyes based on data extracted from the Pentacam Scheimpflug camera and to compare calculations with those from an existing standard. Setting Private practice, Mesa, Arizona. Design Case series. Methods Relevant IOL calculation and postoperative refractive data were obtained for eyes that had previous RK but no additional keratorefractive procedures or subsequent cataract surgery. Various Scheimpflug measurements from examinations before cataract surgery over a range of zone diameters were used to calculate IOL power using an Aramberri double‐K–modified Holladay 1 formula. Results were compared with actual postsurgical data and IOL calculations based on the mean of the 1.0 mm to 4.0 mm rings from the Atlas topography system. Results Data were obtained for 83 eyes of 57 patients, including more than 120 different measures per eye from the Scheimpflug system. The mean pupil‐centered sagittal front power over the central 4.0 mm zone provided the best results after adjustment for central corneal thickness (CCT). Results were similar to those obtained when the IOL power was calculated using the topography system; 42% of eyes were within ±0.50 diopter (D) of the target, and 76% of eyes were within ±1.00 D. Conclusion In this large series of eyes, the calculation of IOL power after RK using sagittal front‐surface power and CCT from the Scheimpflug system produced results equivalent to the multizone approach with the topography system. Financial Disclosure Neither author has a financial or proprietary interest in any material or method mentioned.

Refractive cylinder outcomes after calculating toric intraocular lens cylinder power using total corneal refractive power.

Purpose To determine whether the total corneal refractive power (TCRP) value, which is based on measurement of both anterior and posterior corneal astigmatism, is effective for toric intraocular lens (IOL) calculation with AcrySof® Toric IOLs. Patients and methods A consecutive series of cataract surgery cases with AcrySof toric IOL implantation was studied retrospectively. The IOLMaster® was used for calculation of IOL sphere, the Pentacam® TCRP 3.0 mm apex/ring value was used as the keratometry input to the AcrySof Toric IOL Calculator and the VERION™ Digital Marker for surgical orientation. The keratometry readings from the VERION reference unit were recorded but not used in the actual calculation. Vector differences between expected and actual residual refractive cylinder were calculated and compared to simulated vector errors using the collected VERION keratometry data. Results In total, 83 eyes of 56 patients were analyzed. Residual refractive cylinder was 0.25 D or lower in 58% of eyes and 0.5 D or lower in 80% of eyes. The TCRP-based calculation resulted in a statistically significantly lower vector error (P<0.01) and significantly more eyes with a vector error ≤0.5 D relative to the VERION-based calculation (P=0.02). The TCRP and VERION keratometry readings suggested a different IOL toric power in 53/83 eyes. In these 53 eyes the TCRP vector error was lower in 28 cases, the VERION error was lower in five cases, and the error was equal in 20 cases. When the anterior cornea had with-the-rule astigmatism, the VERION was more likely to suggest a higher toric power and when the anterior cornea had against-the-rule astigmatism, the VERION was less likely to suggest a higher toric power. Conclusion Using the TCRP keratometry measurement in the AcrySof toric calculator may improve overall postoperative refractive results. Consideration of measured posterior corneal astigmatism, rather than a population-averaged value, appears advantageous.

Tarsal conjunctival morphometry of asymptomatic soft contact lens wearers and non-lens wearers

Abstract Soft contact lens wear is known to induce changes in the tarsal conjunctiva; qualitative grading is the current standard for recording such changes. This project was designed to investigate the usefulness of quantitatively assessing the morphometry of the tarsal conjunctiva, through a comparison of eight asymptomatic long-term soft contact lens wearers and eight nonwearers. The right tarsal plates were photographed after staining with fluorescein. A subjective assessment and grading of the fluorescein-highlighted tarsal plates was not able to distinguish the wearers and nonwearers. However, morphometry of the fluorescein-highlighted features across zone 1 of each tarsal plate revealed two basic patterns to the histograms of the areas of these features in both contact lens wearers and nonwearers. The analyses suggest that there are at least two types of “features” highlighted by fluorescein, evident in both wearers and nonwearers. Asymptomatic long-term soft lenswear appears to reduce the size of “small features” and increase the size and variability of “large features”. These differences could be shown to be statistically significant. Further refinement of these quantitative assessment techniques should be useful in defining contact lens wear-related changes in the tarsal conjunctiva.

Cataract surgery and methods of wound closure: a review

Clear corneal incisions are routinely used in cataract surgery, but watertight wound closure may not always be achieved, which can increase the risk for anterior chamber fluid egress or ocular surface fluid ingress. A new US Food and Drug Administration-approved ocular sealant appears to have good efficacy in sealing clear corneal incisions; its use may be indicated when wound integrity is in question.