Mesopic Pupil Diameter Research Articles

Does Dilated Wavefront Aberration Measurement Provide Better Postoperative Outcome after Custom LASIK?

To compare outcomes after custom LASIK based on non-pharmacologically dilated (natural mesopic pupil) and pharmacologically dilated wavefront aberration measurement. Case-control study. The study group included 81 myopic eyes from 81 patients (mean preoperative spherical equivalent [SE], -4.15+/-1.97 diopters [D]). The control group consisted of 87 myopic eyes from 87 patients (mean preoperative SE, -4.98+/-2.00 D). The 81-eye study cohort was treated based on nonpharmacological low mesopic dilated wavefront aberration measurement (Zywave aberrometer), and the postoperative outcome was compared with that of the control group of 87 eyes treated, based on pharmacologically dilated (2.5% neosynephrine) wavefront data, using the Zyoptix platform. The same nomogram was used for both groups, which adjusts sphere based on the amount of preoperative higher-order aberration. All eyes had a low mesopic pupil diameter of > or =6.3 mm without pharmaceutical intervention. Postoperative 3-month visual acuity (VA), contrast sensitivity, and refractive error. Of the non-pharmacologically dilated eyes (study) and pharmacologically dilated (control) eyes, 96.3% and 96.6%, respectively, attained postoperative uncorrected VA of 20/20 or better. Although 96.6% of the eyes were within the target SE of +/-0.50 D in the control group, 100% of the 81 study eyes were within an SE of +/-0.50 D postoperatively. The range of postoperative SE (-0.75 to +1 D) was slightly reduced among the study eyes (+/-0.50 D). Differences were not statistically significant. When a low mesopic pupil dilates to > or =6.3 mm, pharmacological dilation with wavefront-guided ablation may provide no additional benefit with regard to spherical accuracy when compared with nonpharmacological wavefront-guided ablation. The use of the Rochester nomogram, which accounts for aberration interaction, provided excellent results with or without pharmacological dilation.

Visual experience and patient satisfaction with wavefront-guided laser in situ keratomileusis

To determine the correlation between patient perception and clinical measurements after wavefront-guided laser in situ keratomileusis (LASIK). Multicenter clinical trial. In this retrospective analysis of clinical study results in 274 eyes, wavefront-guided LASIK procedures were performed in 274 myopic-astigmatic eyes at 6 sites. Comprehensive evaluations of vision and ocular health were conducted preoperatively and for 6 months postoperatively. Visual acuity and contrast sensitivity were measured, and questionnaires were administered. Questionnaire responses were compared with clinical measurements. The overall distribution shifted toward "more satisfied." The "very satisfied" population increased by as much as 70% in all areas. There was no significant change in frequency of visual symptoms. Patients were more expressive about visual decline than visual improvement. Perception of changes in vision appeared to be related to mesopic contrast sensitivity and mesopic contrast sensitivity under glare. Mesopic pupil diameter was not a major predictor of patient satisfaction. Contact lens wearers were more satisfied with postoperative vision than were spectacle wearers. Men were more likely to report visual symptoms and to complain about night vision, although their changes were the same as those of the women. Residual refractive error was a major predictor for most questionnaire items. Most patients were as satisfied or more satisfied with their postoperative uncorrected visual acuity than with their preoperative best corrected visual acuity. By continuing to minimize postoperative refractive error through the use of nomograms and improved technology, visual complaints such as night glare and halo could be diminished or even eliminated. The study shows that subjective experience affected satisfaction with results. Some dissatisfaction might be mitigated by being sure patients are educated and have realistic expectations before surgery.

Pupillary Dysfunction in Type 2 Diabetes Mellitus to Refine the Early Diagnosis of Diabetic Autonomic Neuropathy

Diabetic autonomic neuropathy (DAN) is one of the most disabling complications of diabetes mellitus. This study aimed to evaluate a special pupillary analysis for the early diagnosis of DAN by investigating pupil responsiveness under different conditions. Images of the pupils of 40 type 2 diabetic patients, who were divided into two (subclinical and nonproliferative diabetic retinopathy [NPDR]) groups using the results of fundus fluorescein angiography, and 20 healthy subjects were taken under mesopic, photopic, and pharmacologically dilated conditions. The pupil diameters, constriction ratio (CR), and dilation ratio (DR) were computed and calculated from the images. The mean mesopic pupil diameters (D1) of the control group, the subclinical group, and the NPDR group were 6.02 ± 0.48, 5.87 ± 0.99, and 4.95 ± 1.12 mm, respectively. The mean photopic pupil diameters (D2) were 3.40 ± 0.33, 3.37 ± 0.31, and 3.25 ± 0.47 mm, respectively. The mean pharmacologically dilated pupil diameters (D3) were 7.37 ± 0.59, 6.91 ± 1.00, and 5.49 ± 1.24 mm, respectively. The mean CR of the three groups were 0.43 ± 0.07, 0.41 ± 0.10, and 0.32 ± 0.14, respectively, and the mean DR were 0.23 ± 0.08, 0.19 ± 0.13, and 0.11 ± 0.05, respectively. There were statistically significant differences between the three groups with regard to the data of dark-adapted pupil diameter, dilated pupil diameter, CR, and DR (p < 0.05). Autonomic pupillary dysfunction occurs early in type 2 diabetic patients. Abnormal pupil responses might be due to a dysfunction of pupillary nerve fibers. In addition, myogenic abnormalities are a causative factor to produce small D1 and DR. Pupillary diameters under mesopic and pharmacologically dilated conditions and the CR and DR of the pupillary function can be reliable parameters to evaluate autonomic neuropathy in type 2 diabetes mellitus patients.

Simplified mathematics for customized refractive surgery

Purpose To describe a simple mathematical approach to customized corneal refractive surgery or customized intraocular lens (IOL) design that allows “hypervision” and to investigate the accuracy limits. Setting University eye hospital, Mainz, Germany. Method Corneal shape and at least 1 IOL surface are approximated by the well-known Cartesian conic section curves (ellipsoid, paraboloid, or hyperboloid). They are characterized by only 2 parameters, the vertex radius and the numerical eccentricity. Residual refraction errors for this approximation are calculated by numerical ray tracing. These errors can be displayed as a 2-dimensional refraction map across the pupil or by blurring the image of a Landolt ring superimposed on the retinal receptor grid, giving an overall impression of the visual outcome. Results If the eye is made emmetropic for paraxial rays and if the numerical eccentricities of the cornea and lens are appropriately fitted to each other, the residual refractive errors are small enough to allow hypervision. Visual acuity of at least 2.0 (20/10) appears to be possible, particularly for mesopic pupil diameters. However, customized optics may have limited application due to their sensitivity to misalignment errors such as decentrations or rotations. Conclusion The mathematical approach described by Descartes 350 years ago is adequate to calculate hypervision optics for the human eye. The availability of suitable mathematical tools should, however, not be viewed with too much optimism as long as the accuracy of the implementation in surgical procedures is limited.

Risk factors for self-reported visual symptoms with Intacs inserts for myopia

Objective Potential risk factors and visual performance measures were evaluated for relationship to self-report of clinical visual symptoms after the refractive procedure for placement of Intacs microthin prescription inserts for myopia. Design Retrospective nonrandomized comparative study. Participants/intervention Patients were participants in the U.S. Food and Drug Administration phase III KeraVision prospective clinical trials. Main outcome measures Study participants (n = 263) were retrospectively classified into one of three outcome groups on the basis of postoperative self-reported visual symptoms and/or request for Intacs inserts removal through month 24. Differences between outcome groups in visual acuity, refractive error, corneal geometry, corneal topography, type of preoperative corrective lens wear, and demographic variables were evaluated with multivariate logistic regression. Results Clinical trial participants who had preoperative mean keratometry >45 diopters (D) (adjusted odds ratio [OR], 0.43; 95% confidence interval [CI], 0.21, 0.85, P = 0.02), manifest refractive astigmatism of 0.75 D or 1.00 D (adjusted OR, 0.52; 95% CI, 0.25, 1.08, P = 0.08), measured uncorrected visual acuity ≥2 lines better than that predicted by their respective cycloplegic refractive error (adjusted OR, 0.39; 95% CI, 0.14, 1.12, P = 0.08) and/or had worn soft contact lenses (adjusted OR, 0.58; 95% CI, 0.32, 1.04, P = 0.07) tended to be less likely to report postoperative clinical visual symptoms with Intacs inserts. Risk of clinical visual symptoms and request for Intacs inserts removal approximately doubled for each 0.50 D of additional postoperative defocus equivalent (crude OR, 1.86; 95% CI, 1.39, 2.48, P = 0.00). Controlling for postoperative defocus and important preoperative risk factors, subjects who reported significant clinical visual symptoms were more likely to have had preoperative uncorrected visual acuity that was worse than that predicted by their respective cycloplegic refractive error (adjusted OR, 1.84; 95% CI, 0.98, 3.42, P = 0.06). Risk of reporting clinical visual symptoms was increased with mesopic pupil diameter ≥6.5 mm (adjusted OR, 1.76; 95% CI, 0.96, 3.24, P = 0.07). Within the group of patients who reported postoperative clinical visual symptoms, 71 of 122 (58%) had ceased reporting them by month 24. Conclusions Adjusting for important risk factors simultaneously, this study suggested that certain preoperative characteristics may increase or decrease the likelihood, depending on the characteristic, of refractive surgery candidates to report significant clinical visual symptoms with Intacs inserts.