Larger Pupil Size Research Articles

Ocular higher-order aberration features 10 years after photorefractive keratectomy

The aim of the present study is to re-evaluate the original cohort of patients who participated in the first photorefractive keratectomy (PRK) trial in the 1990s, especially their optical performance. Forty-four eyes (24 patients) of the original cohort who underwent PRK using the NIDK EC-5000 excimer laser platform returned 10years (range 9-14years) postoperatively to have higher-order aberrations (HOAs) recorded. Wavefront aberrations were measured using Wavescan (VISX, Santa Clara, CA, USA) and calculated for 3- and 6-mm pupil size. The total RMS (the square root of the sum of squared Zernike coefficients) of higher-order wavefront error (3rd-6th radial order) and the Zernike coefficients, as well as the third-order (S 3) and fourth-order (S 4) aberrations, spherical aberrations and coma aberration values were analyzed. An independent sample t test was used for comparisons and a P value<0.05 was considered statistically significant. The mean RMS of higher-order wavefront values showed an increase but no significant difference in postoperative eyes compared to the control-matched normal level with the 6-mm pupil (HOA RMS: control group 0.31±0.12μm; 10-year post-PRK group 0.56±0.15μm; P=0.141). The main contribution was the increase of spherical aberrations (Z 12) and spherical-like aberrations (S 4), which increased by fourfold and 2.5-fold, respectively, in the 10-year post-PRK group (control group Z 12 0.08±0.11μm, S 4 0.14±0.05μm; 10-year post-PRK group Z 12 0.35±0.15μm, S 4 0.37±0.14μm; P=0.010*). Most increases of ocular HOAs induced by corneal refractive surgery are becoming extremely minor at 10years postoperatively, closer to the corresponding preoperative amount. The largest increase was spherical and spherical-like aberrations, especially with a larger pupil size.

Residual Astigmatism Following Toric Intraocular Lens Implantation Related to Pupil Size

To present two patients with residual astigmatism following toric intraocular lens (IOL) implantation. Case reports. A 58-year-old woman underwent toric IOL implantation (spherical power 29.50 diopters [D], cylinder power 3.00 D; SN60T5, Alcon Laboratories Inc) to correct 2.33 D @ 80° of corneal astigmatism. Postoperatively, uncorrected distance visual acuity (UDVA) was 20/30 and corrected distance visual acuity (CDVA) was 20/22 (0 -1.75 × 95), indicating an overcorrection of astigmatism. Slit-lamp examination demonstrated no IOL misalignment. Wavefront aberrometry showed a large pupil diameter (>6 mm) and a lower corneal astigmatism in a 6-mm zone (-1.40 D @ 174°) compared to a 4-mm zone (-2.21 D @ 171°). The second patient, a 60-year-old man, underwent multifocal toric IOL implantation (spherical power 22.50 D, cylinder power 2.25 D; SND1T4, Alcon Laboratories Inc) to correct 1.51 D @ 173° of corneal astigmatism. Postoperatively, UDVA was 20/50 and CDVA was 20/20 (+0.25 -1.00 × 102), indicating an undercorrection of astigmatism. Slit-lamp examination showed no misalignment. Both cases indicate that unexplained residual astigmatism following toric IOL implantation may be the result of multiple factors: the effect of the spherical power and anterior chamber depth on toric IOL calculations, the effect of posterior corneal astigmatism, and the effect of a large pupil size. The first two issues may be compensated for by improving toric IOL calculations. The latter indicates that pupillometry is indicated in relatively young patients who undergo toric IOL implantation.

Optical and visual quality comparison of implantable Collamer lens and laser in situ keratomileusis for myopia using an adaptive optics visual simulator.

Purpose. To compare optical and visual quality of the implantable Collamer lens (ICL) and laser in situ keratomileusis (LASIK) for myopia. Methods. An adaptive optics visual simulator (CRX1, Imagine Eyes, France) was used to simulate the vision after ICL implantation and LASIK procedure from the wavefront aberration pattern for -3 and -6 D. Monocular visual acuity (VA) at different contrasts and contrast sensitivity (CS) at 10, 20, and 25 cycles/degree (cpd) were measured for 3- and 5-mm pupils. Modulation transfer function (MTF) and point spread function (PSF) were calculated for a 5-mm pupil. Results. The ICL showed a MTF near of diffraction-limited MTF, but the post-LASIK of MTF worsened moving away from both curves. Statistically significant differences were found in VA between both procedures for all conditions (p<0.05). For -3 D ICL and LASIK, we did not find statistically significant differences in CS between the procedures for both pupils and any spatial frequencies (p>0.05). But for -6 D ICL and LASIK, the effect of aberrations became apparent, finding statistically significant differences in CS between both procedures for 2 pupils and all spatial frequencies evaluated (p<0.05). In all cases optical and visual quality was better with the ICL procedure. Conclusions. Both ICL and LASIK procedures provide good optical and visual quality, although the ICL provides better outcomes, especially for large refractive errors and pupil sizes. These outcomes are due to the LASIK procedure inducing higher higher-order aberrations than ICL implantation.

Accommodation to wavefront vergence and chromatic aberration.

Longitudinal chromatic aberration (LCA) provides a cue to accommodation with small pupils. However, large pupils increase monochromatic aberrations, which may obscure chromatic blur. In this study, we examined the effect of pupil size and LCA on accommodation. Accommodation was recorded by infrared optometer while observers (nine normal trichromats) viewed a sinusoidally moving Maltese cross target in a Badal stimulus system. There were two illumination conditions: white (3000 K; 20 cd/m) and monochromatic (550 nm with 10 nm bandwidth; 20 cd/m) and two artificial pupil conditions (3 and 5.7 mm). Separately, static measurements of wavefront aberration were made with the eye accommodating to targets between 0 and 4 D (COAS, Wavefront Sciences). Large individual differences in accommodation to wavefront vergence and to LCA are a hallmark of accommodation. LCA continues to provide a signal at large pupil sizes despite higher levels of monochromatic aberrations. Monochromatic aberrations may defend against chromatic blur at high spatial frequencies, but accommodation responds best to optical vergence and to LCA at 3 c/deg where blur from higher order aberrations is less.

Effect of Preoperative Pupil Size on Quality of Vision after Wavefront-Guided LASIK

To evaluate the effect of preoperative pupil size on quality of vision after wavefront-guided LASIK. Prospective study. One hundred two eyes. LASIK for mild to moderate myopia or astigmatism (preoperative manifest spherical equivalent, -3.99±1.42 diopters). Questionnaires evaluating specific visual symptoms before and after surgery. Each eye was evaluated before surgery, and 1 week and 1, 3, 6, and 12 months postoperatively. Pupils were stratified according to size: small (≤5.5 mm), medium (5.6-6.4 mm), or large (≥6.5 mm). Mesopic pupil size and preoperative and postoperative variables were evaluated using an analysis of variance. A regression model was also performed to determine the correlation between mean spherical equivalent and cylinder and visual symptoms. In the early postoperative period, there was no difference between the 3 groups with regard to any of the symptoms. At the final 12-month postoperative visit, patients with medium pupils experienced less glare at night than small pupils (P = 0.02), medium pupils had less halos than small or large pupils (P = 0.001 and P = 0.02, respectively), and medium pupils experienced greater satisfaction in visual improvement than small pupils (P = 0.014). Twelve months after wavefront-guided LASIK surgery, large pupil size does not positively correlate with any postoperative visual symptoms.

Influence of the pupil size on visual quality and spherical aberration after implantation of the Tecnis 1-piece intraocular lens

PurposeTo evaluate the influence of the pupil size on clinical results and objective parameters of optical quality of the Tecnis 1-piece (ZCB00) intraocular lens.SettingCentre of Ophthalmology, Eberhard-Karls University Tübingen, Germany.MethodsIn...

Wavefront aberrometry advances in refractive surgery

AbstractWavefront aberrometry has been adapted from optical astronomy in order to analyze complex image distortions caused by the human optical system, called higher order aberrations. The aberrations increase with larger pupil size or during nocturnal vision when the pupil dilates. They may have a significant impact on vision, even in a patient with 20/20 visual acuity. Most Shack Hartman aberrometers can be used as a super auto refracto‐keratometer during refractive surgery pre‐operative evaluations. They can capture the full amount of astigmatism and so will minimize the need for retreatment due to undercorrection. Modern Shack Hartman aberrometers give also the refractive surgeons the possibility to measure aberrations induced by flap creations. In addition they will be useful for performing customized excimer laser ablation (data coming from the aberrometer mapping out a path for the laser in reshaping the cornea). This technique has been shown to improve the correction of lower order aberrations (90% of the aberrations of the human eye), but is there a real benefit for treating higher order aberrations? Is a Shack Hartman aberrometer needed for every day refractive surgery practice? Thru an evidence based review of the literature confronted to personal experience we will try to answer these questions.

Contrast Sensitivity and Higher Order Aberrations in Eyes Implanted With AcrySof IQ SN60WF and AcrySof SN60AT Intraocular Lenses

Purpose To evaluate the efficacy of the aspheric optic of the AcrySof IQ SN60WF intraocular lens (IOL) in decreasing spherical and total higher order aberrations and improving contrast sensitivity after cataract surgery compared to the spheric AcrySof SN60AT. Methods Fifty-two eyes of 36 patients were evaluated at the University of Texas Southwestern Medical Center at Dallas 3 to 6 months after phacoemulsification with implantation of the AcrySof IQ SN60WF (27 eyes) or AcrySof SN60AT (25 eyes) IOL. Eyes with previous surgery or ocular pathology were excluded. Results Eyes implanted with the AcrySof IQ SN60WF had less total higher order and spherical aberrations than AcrySof SN60AT-implanted eyes at pupils of 4 mm (0.14±60.06 vs 0.18±0.04 µ m and −0.01±0.03 vs 0.09±0.03 µ m, respectively), 5 mm (0.24±0.07 vs 0.34±0.08 µ m and 0.03±0.02 vs 0.23±0.08 µ m, respectively), and 6 mm (0.42±0.13 vs 0.67±0.12 µ m and 0.08±0.04 and 0.46±0.09 µ m, respectively), ( P &lt;.05 for all), with similar mean coma, trefoil, and 5th order aberrations. AcrySof SN60WF eyes showed better contrast sensitivity than AcrySof SN60AT eyes at 12 and 18 cycles per degree (cpd) under mesopic conditions (1.65±0.23 vs 1.51±0.25 and 1.22±0.21 vs 1.01±0.19, respectively), and at 18 cpd under glare (1.12±0.30 vs 0.87±0.31, respectively) ( P &lt;.05). Photopic contrast sensitivity was similar in both groups. The two groups had comparable mean age, axial length, IOL power, and postoperative mesopic and photopic pupil sizes. Conclusions Compared to a spheric optic, the aspheric design of the AcrySof IQ SN60WF reduces spherical aberration, especially under larger pupil sizes, and improves mesopic contrast sensitivity at higher frequencies with and without glare. [ J Refract Surg. 2008;24:619–625.]

Subjective and Autonomic Responses to Smoking-Related Visual Cues

Nicotine, like several other abused drugs, is known to act on the reward system in the brain. Smoking-associated cues produce smoking urges and cravings accompanied by autonomic dysfunction to these cues in smokers. The present study was aimed at investigating whether cues related to smoking elicit the autonomic response in smokers. The subjective and physiological reactivity of 7 smokers and 12 nonsmokers in a supine position to smoking-related visual cues was assessed under indirect dim light using a self-assessment manikin and a specially designed pupillometer. The experimental procedure consisted of the elicitation and measurement of pupil size (PS) while the subjects viewed a smoking image and images from three valence-defined categories (i.e., pleasant, unpleasant, and neutral), based on normative affective ratings selected from the International Affective Picture System. Both groups produced significantly larger PS increases in response to pleasant or unpleasant images compared to neutral images. Smokers, viewing smoking-related visual cues but no other affective images, produced significantly larger PS's compared to nonsmokers. Moreover, smokers rated the smoking image with more pleasure and arousal than nonsmokers. These findings suggest that cues related to smoking induce not only a subjective emotional alteration, but also sympathetic activation, measured by the time-series PS data in smokers.

Long-term optical quality of the photoablated cornea

High-order coreal wavefront analysis was performed in a population of 60 myopic eyes that underwent photorefractive keratectomy. Corneal aberration data over 3, 5, and 7 mm pupils were collected for up to three years after surgery. The optical performance of the anterior cornea was characterized by estimation of the modulation transfer function (MTF) and the point-spread function. The high-order corneal wavefront aberrations were shown to stabilize one year after surgery. Over photopic pupils, after an early slight increase, corneal RMS-high-order aberrations (HOA) tended to decrease toward preoperative values. On the other hand, over mid- and large-pupil sizes, corneal HOA significantly increased compared with the preoperative state, while the optical performance of the cornea was diminished. The MTF ratio showed a distinct decline in the optical quality of postoperative corneas at low and middle spatial frequencies over larger pupils in the range between 6 and 19 c/deg, especially for deeper ablations.

Peripheral fading with monocular and binocular viewing

This study measured the fading times of peripheral targets as a function of whether viewing was monocular or binocular, and of brightness contrast. Data from a binocularly normal group showed Troxler fading to be significantly faster with monocular (i.e., patched) than with binocular viewing. In contrast, one-eyed observers showed significantly longer fading times than the two-eyed observers viewing monocularly and equivalent times to their binocular viewing. A control experiment showed that these findings were not due to worse fixation stability, larger pupil sizes, or an unusually large blinking rate in the enucleated group. The enucleated group actually exhibited a slight miosis, equivalent fixation stability, and a normal blinking rate. In both experiments, the times to fading of all observers were a function of brightness contrast. We conclude that in binocularly normal observers patching or closing one eye does not produce monocular vision but rather a condition of weak binocular rivalry, and that the absence of inhibitory binocular interactions in the enucleated group may explain, in part, their resistance to fading and their superior performance in other contrast-defined tasks.

Comparison of two pupillometers in determining pupil size for refractive surgery

To compare a handheld and a digital pupillometer in determining pupil size in a population of refractive surgery candidates (group 1) and after implantation of an Artisan phakic intraocular lens (PIOL) for correction of myopia (group 2). Pupil size was measured with the Colvard and Procyon pupillometers in 121 eyes in group 1 and 83 eyes in group 2. Pupil sizes measured with the Colvard device were compared with the scotopic, mesopic-low and mesopic-high measurements taken with the Procyon pupillometer in both groups. Analysis of comparison between pupil measurements was performed according to methods described by Bland and Altman. The mean Colvard scotopic pupil diameter, scotopic, mesopic-low and mesopic-high Procyon pupil diameters were 5.86 +/- 0.81 mm, 6.42 +/- 0.88 mm, 5.55 +/- 0.95 mm and 4.21 +/- 0.73 mm in group 1 and 5.32 +/- 0.67 mm, 6.14 +/- 0.81 mm, 5.33 +/- 0.78 mm and 4.02 +/- 0.55 mm in group 2, respectively. The Colvard diameter compared most favourably with the Procyon mesopic-low diameter (group 2; p = 0.78). Measurements of pupil diameter with the Colvard pupillometer correlated best with measurements taken by the Procyon pupillometer under standardized mesopic-low light conditions. We believe that digital binocular infrared pupillometry is advantageous for obtaining standardized measurements of pupil size.

Pupil size and corneal laser surgery

The role of scotopic pupil size as a factor in predicting night vision complaints is controversial. This review summarizes reports in the literature, some that have found and some that have failed to find a correlation with scotopic pupil size and night vision complaints. Pupil-measuring devices are discussed along with informed consent issues and reports showing that wavefront aberrations increase with increasing pupil size. A new objective measuring device (Larson) showed a correlation with postoperative starbursts and pupil size and a decrease in starbursts with wavefront-guided treatments compared with conventional excimer laser treatments. Cortical adaptation allows many patients to adapt to their new night vision. Treatment options for those who remain symptomatic include drops to reduce pupil size and wavefront-guided retreatments. Reports in the literature are conflicting, and refractive surgeons would be wise to inform their patients that large scotopic pupil size is a potential risk factor for night vision complaints. By doing this they will follow the recommendations in recent patient information brochures of both VISX (Santa Clara, California) and Alcon (Orlando, Florida) and on the United States Food and Drug Administration web site.

Comparison of Higher Order Aberrations and Contrast Sensitivity After LASIK, Verisyse Phakic 1OL, and Array Multifocal IOL

To evaluate higher order aberrations and contrast sensitivity after LASIK, implantation of the Verisyse phakic intraocular lens (IOL), and refractive lens exchange with the Array multifocal IOL. In a prospective, non-randomized case series, LASIK was performed in 20 eyes with the Technolas 217z excimer laser (Bausch & Lomb, Rochester, NY), a Verisyse phakic IOL (AMO Inc, Santa Ana, Calif) was implanted in 11 eyes, and refractive lens exchange with implantation of a multifocal IOL (Array IOL, AMO Inc) was performed in 12 eyes. Wavefront error (Zywave aberrometer; Bausch & Lomb) at two pupil sizes (4 and 6 mm) and photopic contrast sensitivity (CVS-1000) was measured preoperatively and 2 months postoperatively in all eyes. Photopic contrast sensitivity remained unchanged in the LASIK and the Verisyse groups, and decrease was significant in the Array group at three cycles per degree only. Higher order aberrations with a 4-mm pupil were increased in the Array group only. With a 6-mm pupil, they were increased in all groups. Comparing groups, surgically induced higher order aberrations were highest after refractive lens exchange with the Array multifocal IOL and lowest after implantation of the Verisyse IOL. Laser in situ keratomileusis, the Verisyse IOL, and the Array IOL increase higher order aberrations at large pupil sizes, but no increase occurs at small pupil sizes with LASIK or the Verisyse IOL. Contrast sensitivity in photopic conditions is normal with LASIK and the Verisyse IOL, but slightly reduced with the Array IOL due to the multifocal optic.

Modulation transfer function and pupil size in multifocal and monofocal intraocular lenses in vitro

To investigate the relationship between pupil size and the modulation transfer function (MTF) of a multifocal intraocular lens (IOL) in vitro and to predict the visual effects in vivo. Department of Ophthalmology and Visual Science, Kitasato University Graduate School of Medical Sciences, Kitasato, Japan. A refractive multifocal IOL (Array SA-40N, Allergan) and a monofocal IOL (PhacoFlex SI-40NB, AMO) were evaluated using the OPAL Vector system and a model eye with a variable effective aperture. With effective pupil diameters of 2.1, 3.0, 3.4, 3.9, 4.6, 5.1, and 5.5 mm, the in-focus and defocus MTFs were measured in the multifocal and monofocal IOLs. With increases in effective pupil diameter, the far MTF progressively decreased at all spatial frequencies. In contrast, the near MTF began to increase at effective pupil diameter 2.1 mm, showed a peak at 3.4 mm, and decreased at diameters greater than 3.4 mm. The ratio of near MTF to far MTF showed an increase with larger effective pupil diameters and at lower spatial frequencies. With a zonal progressive multifocal IOL, the pupil size effected a trade-off between the far and near MTFs: The near MTF increased at the expense of the far MTF at large pupil sizes (effective pupil diameter >3.4 mm). To enhance near vision with a multifocal IOL, the desirable effective pupil diameter should be 3.4 mm or larger.

Influence of ocular chromatic aberration and pupil size on transverse resolution in ophthalmic adaptive optics optical coherence tomography

Optical coherence tomography (OCT) enables visualization of the living human retina with unprecedented high axial resolution. The transverse resolution of existing OCT approaches is relatively modest as compared to other retinal imaging techniques. In this context, the use of adaptive optics (AO) to correct for ocular aberrations in combination with OCT has recently been demonstrated to notably increase the transverse resolution of the retinal OCT tomograms. AO is required when imaging is performed through moderate and large pupil sizes. A fundamental difference of OCT as compared to other imaging techniques is the demand of polychromatic light to accomplish high axial resolution. In ophthalmic OCT applications, the performance is therefore also limited by ocular chromatic aberrations. In the current work, the effects of chromatic and monochromatic ocular aberrations on the quality of retinal OCT tomograms, especially concerning transverse resolution, sensitivity and contrast, are theoretically studied and characterized. The repercussion of the chosen spectral bandwidth and pupil size on the final transverse resolution of OCT tomograms is quantitatively examined. It is found that losses in the intensity of OCT images obtained with monochromatic aberration correction can be up to 80 %, using a pupil size of 8 mm diameter in combination with a spectral bandwidth of 120 nm full width at half maximum for AO ultrahigh resolution OCT. The limits to the performance of AO for correction of monochromatic aberrations in OCT are established. The reduction of the detected signal and the resulting transverse resolution caused by chromatic aberration of the human eye is found to be strongly dependent on the employed bandwidth and pupil size. Comparison of theoretical results with experimental findings obtained in living human eyes is also provided.

Sources of normal and anomalous motion in retinoscopy.

Besides the classic "with," "against," and "neutral" absence of motion, retinoscopic reflexes can display anomalous "with" motion in myopia. A model is presented that explains the source of this anomalous motion, as well as quantifies the appearance of retinoscopic motion in myopia and hyperopia. Various 2 x 2 matrices were created to describe schematic eyes for a +20 D trial lens, a Gullstrand #1 schematic eye, and an infant schematic eye. Rays from the retinoscope were traced paraxially through these matrices over a full transit of the retinoscope beam across the pupil. Retinal position of the edge of the reflex visible to the observer was plotted as a function of pupil sizes from 2 mm to 16 mm for -5.00 D and +2.00 D refractive errors for the +20 D trial lens. The edge of the retinoscopic reflex could be formed by one of two sources: the edge of the retinoscope beam itself, or the shadow cast by the beam against the edge of the pupil. Anomalous "with" motion arose in myopia when the edge of the reflex was formed by the edge of the beam. The edge of the beam was also visible in hyperopia but did not create anomalous motion. The retinoscope peephole was not involved in the formation of the edge of the reflex. The degree of anomalous motion increased with greater myopia and pupil size. Measured pupil sizes needed to completely eliminate anomalous motion agreed well with those predicted by the model, except at the largest pupil sizes. The limit for anomalous motion depended only on pupil size, refractive error, and working distance but not on whether the system matrix represented the trial lens, a Gullstrand #1 eye, or an infant eye. Seeing the edge of the beam at large pupil sizes during retinoscopy creates anomalous "with" motion in myopia but may make the reflex easier to see in hyperopia. Anomalous "with" motion in myopia can be managed by adjustment of pupil size, working distance, or net corrected refractive error. Aside from possible effects of aberrations, retinoscopic motion appears to be consistent across various paraxial optical systems for a given refractive error and pupil size.

Pupil size and night vision disturbances after LASIK for myopia.

To examine whether standardized, preoperative evaluation of pupil sizes can predict the risk of night vision visual disturbances after bilateral laser in situ keratomileusis (LASIK) for myopia. A prospective study was carried out involving 46 patients who underwent bilateral LASIK for myopia. Pupil sizes were measured before surgery using an infrared pupillometer under standardized settings. Pre- and postoperative refraction and best spectacle-corrected visual acuity (BSCVA) were registered. At the 3-month follow-up visit, the patients completed a questionnaire regarding night vision pre- and postoperatively. The mean bilateral, spherical equivalent refraction (SE) was - 8.76 D (range 6.32 to - 12.0 D) preoperatively, and - 1.69 D (range 0 to - 4.38 D) postoperatively. The mean bilateral BSCVA was not changed by the operations. We found a significant correlation between large scotopic pupil sizes and the impression of worsened night vision (p < 0.01). A significant correlation between gender (males) and subjectively reduced night vision postoperatively was also found (p < 0.05). Large pupil size measured preoperatively is correlated with an increased frequency of subjectively experienced post-LASIK visual disturbances during scotopic conditions. We recommend preoperative evaluation of pupil size in all patients prior to LASIK surgery.

This issue of Acta

This issue of Acta

Optimal pupil size in the human eye for axial resolution.

A computer model that incorporates the monochromatic aberrations of the eye is used to determine the optimal pupil size for axial and lateral resolution as it applies to retinal imaging instruments such as the confocal scanning laser ophthalmoscope. The optimal pupil size for axial resolution, based on the aberrations of 15 subjects, is 4.30 mm +/- 1.19 mm standard deviation (sd), which is larger than that for lateral resolution [2.46 mm +/- 0.66 mm (sd)]. When small confocal pinholes are used, the maximum detected light is obtained with a pupil size of 4.90 mm +/- 1.04 mm sd. It is recommended to use larger pupil sizes in imaging applications where axial resolution is desired.