Correlation of Aberrations With Visual Symptoms Using Wavefront Analysis in Eyes After Laser in situ Keratomileusis

Effect of decentration on the quality of vision in two aspheric posterior chamber intraocular lenses: A contralateral eye study

PURPOSE

To perform an intraindividual comparison of the quality of vision and the effect of decentration between two aspheric intraocular lenses: aspheric balanced curve (ABC) design Vivinex iSert XY1 (Hoya Surgical Optics, Singapore) and anterior aspheric design Tecnis ZCB00 (Abbott Medical Optics, CA).

SETTING

Tertiary Eye Care Centre.

DESIGN

Prospective, randomized comparative study using a random number table.

METHODS

Thirty patients were randomized to the implantation of Vivinex iSert XY1 in one eye and Tecnis ZCB00 in the contralateral eye. Then, 12 weeks postoperatively, a laser ray-tracing aberrometer was used to evaluate the visual Strehl ratio, higher-order aberrations (HOA), decentration of IOL from the visual axis and geometric axis, angle alpha, and angle kappa. Contrast sensitivity was measured using the functional visual analyzer.

RESULTS

The visual internal Strehl ratio was higher ( P < 0.05) at all pupil sizes and the spherical aberrations values were lower ( P < 0.05) at larger pupil sizes (5 mm and 6 mm) in the Vivinex group. The mean decentration from the visual axis in the Vivinex group was significantly more than that in the Tecnis group ( P < 0.01). With an increase in angle alpha, there was a greater decline in the visual Strehl ratio for Tecnis; however, there was a statistically significant decline at 3 mm pupil size for Tecnis ZCB00 ( P = 0.028). The contrast sensitivity was similar for both IOLs.

CONCLUSION

In comparison to an anterior aspheric design IOL, the ABC design IOL yielded better quality of vision, neutralized spherical aberrations to a larger extent, and provided a relatively superior quality of vision with decentration.

Clinical outcome of a quadrifocal (trifocal) intraocular lens in Chinese patients: prospective, observational case series

PURPOSE

To report the visual outcomes and quality of vision and life after bilateral implantation of a single-piece trifocal intraocular lens (IOL) in Chinese patients.

SETTING

Hong Kong Sanatorium & Hospital, Hong Kong, China.

DESIGN

Prospective, observational case series.

METHODS

Patients with bilateral implantation of AcrySof IQ PanOptix multifocal IOL were included. Distance, intermediate (60 cm), and near (40 cm) visual acuities (VAs) and contrast sensitivity (CS), defocus curve, preoperative higher-order aberration (HOA), dysphotopsia (0 to 5), satisfaction (1 to 5), spectacle independence, and quality of life were evaluated. The association between preoperative HOA and postoperative halos was also assessed.

RESULTS

54 eyes of 27 patients were included. The mean binocular distance, intermediate, and near uncorrected VA was -0.05 ± 0.06 (20/18), 0.06 ± 0.10 (20/23), and 0.04 ± 0.05 (20/22), respectively. No eyes lost more than 1 line of vision. Binocular CS was comparable with the monocular population norm of older adults. The defocus curve demonstrated that the binocular VA of 20/25 or better was achieved at a power of -3.00 to +0.50 diopters. The mean scores for halos, glare, and starbursts were 2.4 ± 1.4, 0.2 ± 0.8, and 1.4 ± 1.4 (of 5), respectively. The mean satisfaction score was 4.3 ± 0.7 (of 5). All the patients (100%) reported total spectacle independence. The mean vision-targeted composite score of the vision-related quality-of-life questionnaire was 97.2 ± 9.7 (of 100). Preoperative HOA was not associated with postoperative halos.

CONCLUSIONS

Implantation of the trifocal IOL provided satisfactory visual outcomes and quality of vision and life, which resulted in a high rate of spectacle independence.

Early Outcomes of Two Treatment Modes of PresbyLASIK: Monocular vs. Micro-Monovision

PURPOSE

To report the visual, refractive and subjective outcomes of presbyLASIK for the correction of presbyopia.

METHODS

Monocular (20 eyes) or micro-monovision (12 eyes) presbyLASIK was performed on a total of 32 eyes in 16 patients (50% female, average age 55±4.6 years) using the Zeiss VisuMax 400Hz femtosecond and Schwind Amaris 1050RS excimer laser platform. Predictability, safety and efficacy were assessed and compared at 4-6 weeks, 3 months and 6 months. Results were considered significant if P < 0.05.

RESULTS

For monocular treatments, average postoperative spherical equivalent (SE) was 0.1±0.1 D and -0.86±0.5 D at 4-6 weeks postoperatively for distance and near eyes respectively; 90% eyes achieved SE ±1.0 D of the target. Postoperative binocular uncorrected distance (UDVA), intermediate (UIVA) and near visual acuity (UNVA) were -0.03±0.1 LogMAR (20/20), 0.09±0.26 LogMAR (N4) and 0.29±0.11 LogMAR (N6) respectively with 90% patients achieving binocular UDVA of 20/20 or better. For micro-monovision treatments, average postoperative SE was -0.33±0.51 D and -1.60±0.78 D at 4-6 weeks postoperatively for distance and near eyes respectively; 100% eyes achieved SE ±1.0 D of the target. Postoperative binocular UDVA, UIVA and UNVA were 0.05±0.16 LogMAR (20/20), -0.02±0.10 LogMAR (N3) and 0.23±0.08 LogMAR (N5) respectively with 67% patients achieving binocular UDVA of 20/20 or better.

CONCLUSION

Monocular and micro-monovision presbyLASIK are both effective options for the treatment of presbyopia. Monocular treatments are more likely to be well tolerated by patients who prefer to preserve exceptional distance vision, while micro-monovision treatments may be better suited to patients who can tolerate compromises in distance vision in order to attain greater intermediate vision function.

Causes for Rejection of Keratorefractive Surgery in a Central Indian Population

Aim

To identify the reasons for refusing refractive surgery in patients visiting for spectacle-free vision.

Methodology

Medical records of 296 patients who presented for keratorefractive surgery (KRS) from June 2017 to April 2020 at a tertiary eye care center in central India (Government Medical College and Hospital, Nagpur, Maharashtra, India) were reviewed. Demographic details of all the patients and parameters obtained during workup of a case presented for KRSs were captured in an Excel^® sheet and analyzed statistically.

Results

Of the 296 patients who presented for KRS during the study period, 86 (29.1%) patients were denied KRS. The mean pachymetry in the right eye was 505 μm ± 10 μm (range 520-485 μm) and 502 μm ± 7 μm (511-490 μm) in the left eye. Suboptimal corneal thickness (n = 28, 32.6%) was the most common reason for rejection. Other reasons for not recommending the procedure were high myopia (n = 20, 23.3%), spectacle not stable (n = 16, 18.6%), and keratoconus (n = 11, 12.8%). Collagen vascular diseases (n = 3, 3.5%) and anxiety about the procedure (n = 2, 2.3%) were causes unrelated to the procedure. No correlation was observed between corneal thickness and degree of myopia (r = 0.014, p = 0.66).

Conclusion

Patients presenting for KRS exhibit various problems. Meticulous preoperative evaluation is most important for long-term visual outcome. Suboptimal corneal thickness, high myopia, unstable spectacle correction, and keratoconus were the common reasons for not performing KRS in the study population.

Effect of Wavefront Aberrations on Night Vision Problems and Mesopic Contrast Threshold After SMILE

PURPOSE

To investigate the effect of wavefront aberrations on night vision problems and mesopic contrast threshold after small incision lenticule extraction (SMILE).

METHODS

Forty-two participants (84 eyes) who underwent SMILE were included in this prospective observational study. Visual outcomes including uncorrected distance visual acuity (UDVA), subjective manifest refraction, mesopic contrast threshold (Binoptometer 4P; Oculus Optikgeräte GmbH), and higher order aberrations (HOAs) were analyzed before and 3 months after surgery. The patient's night vision satisfaction was assessed using a questionnaire.

RESULTS

The mean spherical equivalent was -5.30 ± 1.38 diopters (D) preoperatively and -0.06 ± 0.15 D postoperatively. UDVA was better than 20/20 in 98.81% of the patients and better than 20/25 in all patients. Scores of night vision satisfaction and glare changed significantly in the postoperative period (F = 8.463, P = .001; F = 69.518, P < .001, respectively). Preoperative spherical diopters (lower order aberrations) were positively correlated with night vision satisfaction (r = -0.329, P = .041) and glare score (r =-0.332, P = .039). Age (odds ratio [OR] = 1.272, 95% CI = 1.019 to 1.589) and preoperative spherical diopter (OR = 0.437, 95% CI = 0.199 to 0.975) were correlated with night vision satisfaction scores by analysis of binary regression. The root mean square value of total HOAs increased 3 months after surgery (t = -6.873, P < .001) with an increase in horizontal coma (Z₃¹) and spherical aberration (Z₄⁰) (P < .001). No correlation was observed between glare score and HOAs; however, patients with higher preoperative myopia demonstrated continuously decreasing contrast under mesopic conditions and higher postoperative horizontal coma.

CONCLUSIONS

Myopic patients with higher preoperative spherical errors experienced more glare at night after SMILE surgery. Postoperative horizontal coma was associated with worse mesopic contrast thresholds. [J Refract Surg. 2021;37(7):446-452.].

Laboratory evaluation of higher-order aberrations and light scattering in explanted opacified intraocular lenses

Background

Intraocular lens (IOL) calcification is a serious condition that can only be treated by removing the clouded lens. Since explantation bears the risk of complications, it is often deferred until the patient finds the symptoms intolerable. Usually, as the IOL opacifies, visual acuity is minimally affected early on. In this study, we assessed the impact of IOL opacification on optical quality.

Methods

We analyzed ten opacified explanted IOLs (Oculentis GmbH). Wavefront aberrations were obtained with a SHSOphthalmic device (Optocraft GmbH), which features a Hartmann-Shack sensor. The root mean square (RMS) of higher-order aberrations (HOAs) was compared. The effect of calcification on image quality was assessed through the Strehl ratio (SR). We detected light scattering with a C-Quant (Oculus GmbH) and expressed it as a straylight parameter.

Results

At 2 mm, 3 mm and 4 mm, the mean RMS (±standard deviation) was 0.033 μm (±0.026 μm), 0.044 μm (±0.027), and 0.087 μm (±0.049), respectively. The mean SR value was 0.81 ± 0.15 at 3 mm, with four IOLs showing a nearly diffraction-limited performance, but in two explants, opacification precluded reliable measurements. Increased straylight was found in all opacified IOLs with a mean value of 150.2 ± 56.3 deg²/sr at 3 mm.

Conclusions

We demonstrated that IOL opacification induces HOAs. However, the RMS remained low, which resulted only in a slight reduction of the SR-derived optical quality. On the other hand, we found a severe straylight elevation in the opacified lenses, which may result in dysphotopsia, such as glare, and subjective complaints, despite good visual acuity.

Recent advances in wavefront-guided LASIK

PURPOSE OF REVIEW

Laser vision correction remains an active area of research, and there have been many recent advances in the field. The purpose of this review is to provide an update on the recent advances for one of the most common methods of laser vision correction, wavefront-guided laser in-situ keratomileusis (LASIK).

RECENT FINDINGS

Recent technological advancements in wavefront aberrometry are largely responsible for the improved visual outcomes that have been recently reported. In addition, improvements in femtosecond and excimer laser technology, used in flap creation and corneal ablation, have been shown to provide superior results when compared to microkeratomes and earlier lasers. Wavefront-guided LASIK appears to have advantages over some other keratorefractive modalities in terms of visual acuity, predictability, astigmatism correction, and subjective visual symptoms. Nonetheless, there may be some limitations in highly aberrated corneas, and also in biomechanical stability relative to other available platforms.

SUMMARY

Improvements in wavefront aberrometry, and also femtosecond and excimer lasers, have continued to improve our ability to correct refractive errors. Wavefront-guided LASIK remains a well tolerated and effective keratorefractive procedure, with a trend toward superiority. Nonetheless, further studies comparing this modality to others are needed to define the role each can serve.

Accelerated versus standard corneal collagen cross-linking in pediatric keratoconus patients: 24 months follow-up results

PURPOSE

To compare the 24 month visual, refractive, topographic and aberrometric results of the accelerated and standard corneal collagen cross-linking (CXL) in pediatric keratoconus patients.

METHODS

87 eyes of 64 consecutive keratoconus patients under 18 years old with 24 month follow-up period following standard or accelerated CXL were included. 38 eyes received standard CXL (3 Mw/cm², 30 min), while 49 eyes had accelerated CXL (9 mW/cm², 10 min). Changes in the uncorrected (UCVA) and best corrected visual acuity (BCVA), spherical equivalent (SE), manifest astigmatism (MA), corneal topographic parameters, and corneal aberrations such as spherical aberration (SA), high order aberrations (HOAs), horizontal and vertical coma were evaluated. Corneal haze was graded and progression rate was assessed.

RESULTS

The difference between baseline and 24 months postoperative UCVA, BCVA, SimK (keratometry)-1, SimK-2, Kmax, and the corneal aberrations were not significantly different between the two groups (p > 0.05 for all). The mean reduction in thinnest corneal pachymetry from baseline to 24 months after CXL was higher in accelerated CXL group (p = 0.007). The progression rate was 13.1% in standard and 16.3% in accelerated group (p = 0.754). There were no differences in the grade of corneal haze between the two groups (p = 0.249). No complications were observed in the both groups.

CONCLUSION

The 24 month results of accelerated and standard CXL revealed that, the efficacy and safety of accelerated CXL were the same with standard CXL in pediatric keratoconus patients. As being a rapid procedure, accelerated CXL appears to be more benefical for pediatric patients.

Comparison of Measurements and Clinical Outcomes After Wavefront-Guided LASEK Between iDesign and WaveScan

PURPOSE

To compare the measurements of refractive errors and ocular aberrations obtained using iDesign and WaveScan (Abbott Medical Optics, Inc., Santa Ana, CA), and to compare surgical outcomes of wavefront-guided LASEK using ablation profiles based on both aberrometers.

METHODS

Ninety myopic eyes of 45 normal patients were evaluated using both the iDesign and WaveScan to measure spherical and cylindrical errors, spherical equivalents, and Zernike coefficients of ocular aberrations. Wavefront-guided LASEK was performed in a different group of 59 eyes of 30 patients divided into two groups, the iDesign and Wavescan groups. The clinical outcomes between the two groups including uncorrected visual acuity, refractive errors, contrast sensitivity, and ocular aberration were compared at 1, 3, and 6 months postoperatively.

RESULTS

The iDesign produced significantly higher myopic values for refractive errors than the WaveScan, as well as significantly lower levels of total higher order, third, fourth, and fifth order root mean square values and Zernike coefficients of vertical coma and spherical aberration. At postoperative 1, 3, and 6 months, there were no statistically significant differences between the two groups in terms of uncorrected visual acuity and remaining refractive errors. The percentages of patients with spherical equivalents within ±1.00 and ±0.50 diopters of emmetropia were 100% (29 eyes) and 75.9% (22 eyes), respectively, in the iDesign group and 96.7% (29 eyes) and 70.0% (21 eyes), respectively, in the WaveScan group. Mesopic contrast sensitivity values were significantly higher, and the change in root mean square values for spherical aberration was significantly lower in the iDesign group.

CONCLUSIONS

There were significant differences between the iDesign and the WaveScan in the measurements of refraction and ocular aberrations. Wavefront-guided LASEK based on an ablation profile from the iDesign demonstrated comparable refractive predictability with the WaveScan group, resulting in minimal physician adjustment and superior postoperative visual quality.

Corneal asphericity and spherical aberration after refractive surgery

PURPOSE

To evaluate changes in corneal asphericity (Q) and spherical aberrations after refractive surgery using Scheimpflug imaging.

SETTING

University of California, San Diego, Shiley Eye Center, La Jolla, California, USA.

DESIGN

Cohort study.

METHODS

After wavefront-guided laser in situ keratomileusis, patients within ± 0.50 diopter of plano and with an uncorrected distance visual acuity of at least 20/20 were evaluated. The Q values and corneal spherical aberration Zernike values were obtained using Scheimpflug imaging preoperatively and 1 to 3 months postoperatively.

RESULTS

The study enrolled 177 myopic eyes and 32 hyperopic eyes. The mean Q value was -0.28 ± 0.11 (SD) and -0.22 ± 0.15, respectively, preoperatively and +0.35 ± 0.44 and -0.64 ± 0.31, respectively, postoperatively. The asphericity change was highly correlated with preoperative spherical equivalent (r(2) = 0.81; P ≤ .001). The mean corneal spherical aberration was +0.21 ± 0.08 μm in myopic eyes and +0.36 ± 0.11 μm in hyperopic eyes preoperatively and +0.36 ± 0.17 μm and 0.00 ± 0.29 μm, respectively, postoperatively. The corneal spherical aberration changes were correlated with the amount of preoperative refractive error (r(2) = 0.34; P < .001). There was a tendency for Q values and spherical aberrations to become more positive after myopic ablation and more negative after hyperopic ablation.

CONCLUSIONS

Myopic and hyperopic corrections induced changes in the Q value and spherical aberrations in opposite directions (ie, positive and negative, respectively). The changes depended on the magnitude of the refractive correction.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Changes in wave-front aberrations after rigid gas permeable contact lens fitting in post-laser in situ keratomileusis patients with visual complaints

OBJECTIVE

To evaluate the effect of rigid gas permeable (RGP) contact lenses in reducing wave-front aberrations in post-laser in situ keratomileusis (LASIK) myopic patients.

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirty patients with visual complaints after conventional LASIK procedure for correcting myopia.

METHODS

The 30 patients were fitted with RGP contact lenses. Wave-front measurements were taken before and after RGP contact lens wearing.

RESULTS

Compared with bare eye examinations, root mean-square values of higher-order aberrations (HOAs) significantly decreased with RGP contact lens use. Among these, spherical aberration decreased from 0.507 (SD 0.304) microm to 0.164 (SD 0.121) microm (t = 7.186, p < 0.001); coma decreased from 0.470 (SD 0.312) microm to 0.165 (SD 0.090) microm (t = 5.566, p < 0.001); secondary coma decreased from 0.079 (SD 0.050) microm to 0.044 (SD 0.027) m (t = 4.118, p < 0.001); and total HOAs decreased from 0.782 (SD 0.449) microm to 0.307 (SD 0.140) microm (t = 6.710, p < 0.001).

CONCLUSIONS

Fitting RGP contact lenses effectively decreased HOAs induced by conventional myopic LASIK surgery. Possible reasons may be the elimination of irregularity and dissymmetry on the corneal anterior surface, relief of the aspherical extent of the central corneal surface, and enlargement of the effective optical zone.

Visual acuity and higher-order aberrations with wavefront-guided and wavefront-optimized laser in situ keratomileusis

PURPOSE

To compare visual acuity and higher-order aberrations (HOAs) after wavefront-guided and wavefront-optimized laser in situ keratomileusis (LASIK).

METHODS

This retrospective study comprised refraction-matched myopic eyes that had wavefront-guided (Visx Star S4 laser) or wavefront-optimized (WaveLight Allegretto Wave laser) LASIK targeted for emmetropia. Preoperative and postoperative manifest refraction spherical equivalent (MRSE), uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and preoperative and postoperative HOAs were compared.

RESULTS

Preoperatively, there were no significant differences between the wavefront-guided and wavefront-optimized groups in age, sex, corneal thickness, MRSE, or HOAs (all P>.05). The mean MRSE was -2.88 diopters (D) +/- 2.6 (SD) and -2.96 +/- 2.6 D, respectively, preoperatively and -0.01 +/- 0.25 D and -0.02 +/- 0.33 D, respectively, postoperatively; 96% of all eyes were within +/-0.50 D of emmetropia postoperatively. There were no differences in UDVA, CDVA, MRSE, or HOAs between groups (all P>.05). The UDVA was 20/20 or better in 85% of eyes in the wavefront-guided group and 86% of eyes in the wavefront-optimized group. All eyes had 20/25 or better CDVA postoperatively; no eye lost 2 lines of CDVA. Fourteen eyes were converted from wavefront-guided to wavefront-optimized treatment because of poor limbal ring alignment (8 eyes), a wave scan not consistent with the manifest refraction (5 eyes), and no iris registration (1 eye).

CONCLUSIONS

Wavefront-guided LASIK and wavefront-optimized LASIK produced equivalent visual outcomes and no differences in HOAs. Wavefront-guided treatment could not be performed in many eyes because of difficulties during wavefront measurement.

Diplopia and strabismus following ocular surgeries

Postoperative diplopia and strabismus may result from a variety of ocular surgical procedures. Common underlying mechanisms include sensory disturbance, scarring, direct extraocular muscle injury, myotoxicity from injections of local anesthesia or antibiotics, and malpositioning of extraocular muscles by implant materials. The most common patterns are vertical and horizontal motility disturbance. Treatment options include prisms, botulinum, occlusion, or surgery.

Effects of monochromatic aberration on visual acuity using adaptive optics

PURPOSE

To investigate the effect on visual acuity of correcting specific Zernike aberrations.

METHODS

Visual acuity was tested for 12 young subjects using a Freiburg Acuity Test procedure under conditions with wavefront aberrations corrected by an adaptive optics system. The adaptive optics system consists of a Hartmann-Shack wavefront sensor, a deformable mirror, relevant optical channels and closed loop control system. Five aberration correction paradigms were used to correct different Zernike terms.

RESULTS

With the second order aberration fully corrected, a significant improvement in visual acuity was observed (0.056 logMAR, t = 2.79, p = 0.018). Further correction of third order Zernike aberrations resulted in an additional improvement of 0.041 logMAR (t = 2.63, p = 0.023). But an additional correction of spherical aberration did not produce a significant increase in visual acuity (t = 1.10, NS). Full correction of aberrations achieved the best visual acuity with an improvement of 0.022 logMAR (t = 2.46, p = 0.032). The visual acuity was found to increase with the root mean square values of the residual aberrations with a linear relationship (r = 0.63, p < 0.0001).

CONCLUSIONS

Correction of monochromatic wavefront aberrations improves visual acuity for normal eyes and the improvement of visual acuity is proportional to the change of root mean square of wavefront aberrations.

Higher-order aberrations after wavefront-optimized photorefractive keratectomy and laser in situ keratomileusis

PURPOSE

To analyze the changes in higher-order aberrations (HOAs) that occur after wavefront-optimized photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

SETTING

Emory Eye Center and Emory Vision, Atlanta, Georgia, USA.

METHODS

This retrospective analysis comprised eyes that had PRK or LASIK from June 2004 through October 2005. Postoperative outcome measures included 3-month uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction spherical equivalent (MRSE), changes in the root mean square (RMS) and grouped coefficient HOAs (microns) measured with a corneal analyzer, and subjective assessment of visual aberrations.

RESULTS

One hundred consecutive eyes of 54 patients had PRK, and 100 contemporaneous consecutive eyes of 71 patients had LASIK. The PRK and LASIK populations were similar in general demographics, preoperative HOAs, and postoperative UCVA and BSCVA. The mean MRSE was slightly hyperopic after PRK (mean +0.11 diopters [D]) and slightly myopic after LASIK (mean -0.19 D) (P< .0001). There were no statistically significant changes in RMS or grouped coefficient HOA values after PRK or LASIK, nor were there significant differences in postoperative RMS or grouped coefficient HOA values between PRK and LASIK. One percent of PRK and LASIK patients reported a subjective increase in postoperative visual aberrations; 5% reported a subjective improvement postoperatively.

CONCLUSIONS

Wavefront-optimized excimer laser surgery did not induce significant HOAs after PRK or LASIK. The 2 techniques were equally efficacious and had equivalent postoperative HOA profiles.

Ocular aberrations measured by the Fourier-based WaveScan and Zernike-based LADARWave Hartmann-Shack aberrometers

PURPOSE

To evaluate agreements in lower and higher order aberration measurements by two Hartmann-Shack wavefront-sensing devices.

METHODS

Using the VISX WaveScan and Alcon LADARWave aberrometers, ocular aberrations at a fixed optical zone of 6 mm were measured on 36 eyes of 18 patients. A tunable light intensity source was used to control pupil size, which was checked using infrared pupillometry. Repeatability of measurements was evaluated using the intra-class correlation coefficient with 3 consecutive measurements on each aberrometer.

RESULTS

Mean absolute defocus for WaveScan and LADARWave was 2.82 +/- 2.69 and 2.93 +/- 3.24 root-mean-square (RMS) microm, whereas astigmatism was 0.81 +/- 0.49 and 0.87 +/- 0.57 microm, respectively. Pearson correlation coefficients between the two aberrometers were 0.908 and 0.870 for defocus and astigmatism, respectively, whereas higher order aberration correlation was less tight (Pearson correlation coefficient=0.596 for coma, 0.746 for trefoil, 0.836 for spherical aberration, 0.637 for secondary astigmatism, and 0.963 for quadra-foil [P<.001 for all]). The LADARWave had a tendency to display more spherical aberration than the WaveScan, especially at high aberration values, with mean absolute difference in measurement of 0.12 +/- 0.08 microm, and only 44% of eyes having less than +/-0.10 RMS microm of difference. The mean total higher order aberration absolute difference was 0.14 +/- 0.14 microm, with only 50% of eyes within +/-0.1 RMS of agreement. Vector analysis revealed appreciable discrepancies in third- and fourth-order directional Zemike components, while showing similar values for fifth-order components. Intra-class correlation coefficient values for both aberrometers over different aberration orders showed excellent repeatability.

CONCLUSIONS

The WaveScan and LADARWave share similar lower order aberration measurements, but display significantly different higher order aberration values.

Rainbow glare as an optical side effect of IntraLASIK

PURPOSE

To report a new optical side effect associated with the IntraLASIK procedure.

DESIGN

Retrospective chart review and questionnaire of all patients treated with IntraLASIK from June 2004 to August 2005.

PARTICIPANTS

A cohort of 585 eyes (312 patients) was divided sequentially into those treated with the older-model IntraLase laser (group 1: 399 eyes of 215 patients) and those treated with the newer model (group 2: 186 eyes of 97 patients).

METHODS

Preoperative and postoperative refraction, visual acuity, pupillometry, pachymetry, intraocular pressure, mean topographic power and cylinder, wavefront aberrations, and answers to a questionnaire of symptoms were recorded. The precise spatial extent of the rainbow spectrum was drawn by select patients for calculation of the diffractive grating size responsible for the light scatter. A glass slide was also irradiated and photographed using the older model to simulate the rainbow spectrum.

MAIN OUTCOME MEASURES

The symptom of rainbow glare was correlated with preoperative and postoperative factors and time between the most recent service call and surgery.

RESULTS

In group 1, 90.2% of patients were successfully contacted, and 37 (69 eyes) reported symptoms of rainbow glare around lights, for an incidence of 19.07%. In group 2, 88.6% of patients were contacted, and 2 (4 eyes) reported similar symptoms, for an incidence of 2.32%. The odds ratio (OR) between the 2 groups is 9.4 (P<0.001). For every 10-mum increase in ablation depth, the OR is 1.2 (P = 0.038), and for every 30 days from the last service call, it is 1.5 (P = 0.007). The spatial extent of the color pattern was used to calculate the spacing array at approximately 9 mum, corresponding to the laser spot and line separation.

CONCLUSIONS

Light scattering from the back surface of the IntraLASIK flap creates a spectral pattern whose visual impact is clinically inconsequential in the majority of patients. The spectral pattern and visual angle correspond to a grating size that matches the raster spot separation of IntraLase pulsing. Eyes treated with newer focusing optics of higher numerical aperture reduced the rainbow symptom. Variance in optical quality and numerical aperture can impact the spot size and uniformity of IntraLase flap creation.

Higher Order Aberrations and Relative Risk of Symptoms After LASIK

PURPOSE

To understand what level of higher order aberrations increases the relative risk of visual symptoms in patients after myopic LASIK.

METHODS

This study was a retrospective comparative analysis of 103 eyes of 62 patients divided in two groups, matched for age, gender, pupil size, and spherical equivalent refraction. The symptomatic group comprised 36 eyes of 24 patients after conventional LASIK with different laser systems evaluated in our referral clinic and the asymptomatic control group consisted of 67 eyes of 38 patients following LADARVision CustomCornea wavefront LASIK. Comparative analysis was performed for uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), contrast sensitivity, refractive cylinder, and higher order aberrations. Wavefront analysis was performed with the LADARWave aberrometer at 6.5-mm analysis for all eyes.

RESULTS

Blurring of vision was the most common symptom (41.6%) followed by double image (19.4%), halo (16.7%), and fluctuation in vision (13.9%) in symptomatic patients. A statistically significant difference was noted in UCVA (P = .001), BSCVA (P = .001), contrast sensitivity (P < .001), and manifest cylinder (P = .001) in the two groups. The percentage difference between the symptomatic and control group mean root-mean-square (RMS) values ranged from 157% to 206% or 1.57 to 2.06 times greater.

CONCLUSIONS

Patients with visual symptoms after LASIK have significantly lower visual acuity and contrast sensitivity and higher mean RMS values for higher order aberrations than patients without symptoms. Root-mean-square values of greater than two times the normal after-LASIK population for any given laser platform may increase the relative risk of symptoms.

Wavefront-guided LASIK for Myopia Using the LADAR CustomCornea and the VISX CustomVue

PURPOSE

To evaluate the objective and subjective visual outcomes and refractive results of wavefront-guided LASIK with LADAR CustomCornea and VISX CustomVue.

METHODS

This prospective randomized single-institution multisurgeon study comprised 100 eyes of 58 patients (50 eyes on each laser platform). Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and manifest refraction were measured postoperatively at 1 day, 1 week, 1 month, and 3 months. Contrast sensitivity, higher order aberrations measurement, and a subjective vision questionnaire were performed preoperatively and at 3 months.

RESULTS

Preoperatively, the CustomCornea group had a mean manifest sphere of -3.58 +/- 1.61 diopters (D) (range: -0.50 to -7.25 D), cylinder of +0.64 +/- 0.45 D (range: 0 to +1.75 D), and manifest refractive spherical equivalent (MRSE) of -3.26 +/- 1.56 D. The CustomVue group had a manifest sphere of -4.00 +/- 1.69 D (range: -1.50 to -7.50 D), cylinder of +0.60 +/- 0.52 D (range: 0 to +2.00 D), and MRSE of -3.70 +/- 1.64 D. At 3 months, 94% of CustomCornea eyes and 84% of CustomVue eyes had UCVA > or = 20/20 (P = .20). Twenty-four percent of CustomVue eyes and 22% of CustomCornea eyes gained 1 line of BSCVA. In both groups, 96% of eyes were within 0.50 D of emmetropia. Mean CustomCornea glare contrast sensitivity improved (P = .04) whereas more eyes improved than worsened in both groups. Spherical aberration and total higher order aberrations increased, and trefoil decreased in both groups. A decrease in coma was noted in 70% of CustomCornea eyes.

CONCLUSIONS

Wavefront-guided LASIK with both platforms is safe, effective, and delivers excellent visual results. CustomCornea improves contrast sensitivity under glare conditions.

Topographic- and Wavefront-guided Customized Ablations With the NIDEK-EC5000CXII in LASIK for Myopia

PURPOSE

To assess refractive outcomes, changes in the total higher order root mean square (RMS) aberration, and changes in higher order wavefront aberrations after LASIK for myopia and myopic astigmatism with the NIDEK Advanced Vision Excimer Laser platform (NAVEX) using either an aspheric or topography-based or whole eye wavefront ablation algorithm.

METHODS

This was a retrospective study of 1459 eyes that underwent LASIK for myopia and myopic astigmatism. The mean preoperative spherical equivalent refraction was -4.68 diopters (D) (range: -0.50 to -9.63 D) with astigmatism up to -4.50 D. Treatments were classified into three categories depending on the type of ablation algorithm used--optimized aspheric transition zone (OATz) denoted eyes that underwent aspheric treatment zones; customized aspheric treatment zone (CATz) denoted eyes that underwent customized ablations based on corneal topography; and OPDCAT denoted eyes that underwent customized ablation based on the whole eye wavefront profile. Follow-up data are reported at 3 months (69%) and 12 months (17%) postoperatively.

RESULTS

Three months after LASIK, the predictability (10.5 D from target refraction) was 80% for OATz, 91% for CATz, and 76% for OPDCAT. Of all eyes, 96% were within +/- 1.0 D of intended refraction 3 months postoperatively and 100% after 12 months (87% +/- 0.5 D). In the aspheric and custom groups, a notable improvement of uncorrected visual acuity was noted between 3 and 12 months after LASIK. No eye lost >1 line of best spectacle-corrected visual acuity. Mean higher order RMS increased in all groups.

CONCLUSIONS

The data support that the treatment of myopia and myopic astigmatism is safe and effective with NAVEX. Customized ablation based on corneal topography rather than on total wavefront error was more predictable.

Pupil measurement using the Colvard pupillometer and a standard pupil card with a cobalt blue filter penlight

PURPOSE

To compare scotopic pupil measurements obtained with a Colvard pupillometer with measurements taken with a printed pupil gauge and penlight with a cobalt blue filter attachment in mesopic and scotopic luminance.

SETTING

The Illinois Eye Institute, Chicago, Illinois, USA.

METHODS

Pupil measurements were taken of both eyes of 38 patients (76 eyes). Any subject presenting with anterior segment disease, fixed or dilated pupils, iris abnormalities, or a history of eye disease or eye trauma was excluded. At a mesopic luminance of 2.11 foot-candles, pupil measurements were taken with a Bernell pupil card and penlight with a cobalt blue filter attachment. At a scotopic luminance of less than 2.00 foot-candles, pupil measurements were taken with the Bernell card system and the Colvard pupillometer.

RESULTS

In mesopic luminance, the mean pupil diameter was 5.17 mm (range 3.0 to 7.5 mm) with the Bernell card method. The mean difference between the Colvard in scotopic luminance and the Bernell card system in mesopic luminance was -0.04 mm (P = .0831). In scotopic luminance, the mean pupil diameter was 6.32 mm (range 4.0 to 8.0 mm) with the Bernell card method and 5.13 mm (range 3.0 to 7.5 mm) with the Colvard pupillometer, with a mean difference of -1.18 mm (P<.0001). The limits of agreement between the mesopic Bernell card system and the Colvard pupillometer were small (-0.32 to 0.24), whereas the limits of agreement between the scotopic measurements of both techniques were large (-2.18 to -0.18).

CONCLUSIONS

Under both illuminance conditions, the Bernell card system with the cobalt filter measured a larger pupil size than the Colvard pupillometer. The measurement differences between the techniques were most pronounced at the lower illumination. The limits of agreement were larger under the lower illumination, indicating more variation between techniques. This study suggests that the Bernell card system with cobalt illumination provides a generous measurement of the pupil size compared with the Colvard pupillometer, which makes it an appropriate and cost-effective screening tool for refractive surgery evaluation.

Precision of Higher Order Aberration Repeatability With NIDEK OPD-Scan Retinoscopic Aberrometry

PURPOSE

To evaluate repeatability of the total high order aberrations with a retinoscopic wavefront sensor.

METHODS

This prospective case series analyzed 12 eyes from 6 patients who underwent wavefront measurement using retinoscopic aberrometry with the NIDEK Optical Path Difference Scan (OPD-Scan). Four consecutive wavefront measurements of each eye were taken by two trained examiners for 5.8+/-0.8-mm and 8.2+/-0.6-mm pupils (P=.002, Wilcoxon test). Total high order aberrations out to the eighth order were assessed including third order coma, third order trefoil, fourth order quadrafoil, fourth order secondary astigmatism, and fourth order spherical aberrations. Differences between measurements of all of the variables were analyzed. A P value <.05 was considered statistically significant.

RESULTS

Repeatability analysis of the root-mean-square of total higher order aberrations, coma, trefoil, quadrafoil, secondary astigmatism, and spherical aberrations for both dilated and nondilated pupils did not show a statistically significant difference among all repeated measurements, except for trefoil and secondary astigmatism (analysis of variance and the Friedman test). The repeatability of total higher order aberrations was 0.15 microm for nondilated pupils and 0.18 microm for dilated pupils. Except for trefoil measurements, all high order aberrations showed reproducibility >0.15 microm when Zernike coefficients were analyzed individually.

CONCLUSIONS

The NIDEK OPD-Scan aberrometer measures total higher order astigmatism and most individual aberrations with acceptable repeatability. However, measurement of trefoil with this instrument is less repeatable.

Predicting patients' night vision complaints with wavefront technology

PURPOSE

To evaluate the accuracy of the diagnostic capabilities of optical metrics generated from wavefront measurements in relationship to post-laser-assisted in situ keratomileusis (LASIK) visual complaints as expressed and drawn by patients.

DESIGN

Retrospective analysis and observational case series.

METHODS

Patient wavefront data from an investigational device exemption study for wavefront-guided ablations were used to derive normative modulation transfer function (MTF), encircled energy (EE), and Strehl ratio. These optical metrics and their point-spread functions (PSF) were compared with data from five postoperative patients with night vision complaints. Patients were asked to draw their symptoms, which were elicited by testing with a Fenthoff muscle light, while using their best-corrected distance vision.

RESULTS

The MTF, EE, and Strehl ratio of most patients were markedly different from those of the averages of 208 normal myopic eyes before and after LASIK surgery. The spatial extent of the PSF correlated positively with the severity of the visual complaints. Wavefront-derived PSFs were markedly similar to the patients' drawings.

CONCLUSIONS

The results of this study demonstrate the diagnostic capability of the wavefront system in predicting visual symptoms and complaints of patients with high-order aberrations. Objective visual metrics from patients with night vision complaints were different from those of normal myopic eyes that had undergone LASIK procedures.

Conventional vs Wavefront-guided LASIK Using the LADARVision4000 Excimer Laser

PURPOSE

To compare outcomes after LASIK surgery using the conventional LADARVision4000 laser and the wavefront-guided LADARWave CustomCornea wavefront system.

METHODS

A prospective study was performed involving 140 myopic eyes receiving conventional or CustomCornea LASIK between May and October 2003. The preoperative manifest spherical equivalent refraction was limited to myopia < or = -7.00 diopters (D). The preoperative manifest cylinder was limited to < or = -2.50 D of astigmatism. Patients were evaluated for 3 months following surgery. Results evaluated were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity, manifest refraction, dilated wavefront measurements, contrast sensitivity, and patient responses to subjective questionnaires.

RESULTS

For the CustomCornea eyes at 3 months, 80% (70/87) had UCVA > or = 20/20 and 95% (83/87) had UCVA > or = 20/25. For the conventional eyes at 3 months, 45% (9/20) had UCVA > or = 20/20 and 80% (16/20) had UCVA > or = 20/25. At the 3-month postoperative visit, 85% (74/87) of the CustomCornea eyes and 55% (11/20) of the conventional eyes were within +/- 0.50 D of their intended correction. At 1 and 3 months, the CustomCornea treated eyes had a statistically significant lower mean increase in higher order aberrations than conventionally treated eyes (P < .05).

CONCLUSIONS

CustomCornea wavefront-guided LASIK surgery appears safe and effective and provides clinical benefits that appear to exceed those of conventional LADARVision surgery.

Higher Order Aberrations After LASIK for Myopia With Alcon and WaveLight Lasers: A Prospective Randomized Trial

PURPOSE

To evaluate the differences in higher order aberration outcomes between bilateral wavefront-guided and wavefront-optimized LASIK treatments on two closely matched patient groups 1 and 3 months following surgery.

METHODS

Thirty patients were enrolled in the study and randomly assigned to undergo bilateral LASIK with either the Alcon CustomCornea laser system or the WaveLight Allegretto Wave laser system. Standard clinical outcomes such as visual acuity and manifest refraction were evaluated as well as quality of vision measures such as subjective questionnaires and higher order aberrations. All patients completed follow-up examinations for 3 months following surgery.

RESULTS

At 1 and 3 months after surgery, the uncorrected visual acuity and the refractive outcome were similar for the two laser platforms, with 90% to 93% eyes being within +/- 0.5 D of intended outcome. At 1 and 3 months the Alcon CustomCornea group had a statistically significant lower amount of induced total higher order aberrations compared to the Allegretto Wave group (P < .05).

CONCLUSIONS

LASIK for myopia with the Alcon CustomCornea and WaveLight Allegretto Wave systems is highly effective in terms of refractive outcome and uncorrected visual acuity. However, aberrations were statistically significantly greater after treatment with the WaveLight Allegretto Wave system than with the Alcon CustomCornea.

Systematic evaluation of wavefront-guided outcomes

PURPOSE

To present a format for reporting outcomes of aberrometer-guided refractive procedures.

SETTING

SurgiVision Consultants, Inc., Scottsdale, Arizona, and Food and Drug Administration, Center for Devices and Radiological Health, Rockland, Maryland, USA.

METHODS

Reports of standard refractive and visual outcomes (uncorrected visual acuity, manifest refractive spherical equivalent, best spectacle-corrected visual acuity) should be provided for any refractive surgery report. Comparison of postoperative uncorrected visual acuity to preoperative best spectacle-corrected visual acuity should be included. Aberration reports should convert 2nd-order terms to refractions (measured in diopters) and use standard refractive reporting methods. Changes in coma, spherical aberration, and root-mean-square changes should be described using statistical methods for aggregate data. Underlying statistics should be reported.

RESULTS

Aberration changes are well described by the mean error of the attempted versus achieved outcomes, comparison of the mean changes, and stability over time. Ancillary plots include histogram representation of the postoperative scores. Additional reports of visual function should be included, as appropriate.

CONCLUSION

Use of standardized tables and graphs permits qualitative and quantitative comparison of outcomes of refractive treatment with wavefront-guided lasers. Modifications of the recommended formats can be expected over time.

CustomCornea wavefront retreatment after conventional laser in situ keratomileusis

PURPOSE

To evaluate the safety and efficacy of performing laser in situ keratomileusis (LASIK) retreatment using the Alcon CustomCornea system in patients who had prior myopic LASIK using conventional (nonwavefront) software.

SETTING

Private practice ophthalmology clinic, St. Paul, Minnesota, USA.

METHODS

In this prospective interventional trial, consecutive patients having CustomCornea retreatment following conventional LASIK were evaluated. Main outcome measures were uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive error, and higher-order aberrations (HOAs).

RESULTS

Fourteen eyes of 10 patients were evaluated, with a mean follow-up of 5.3 months (range 6.2 to 15.4 months). Mean UCVA improved from 20/50 (logMAR) to 20/26 (P<.001). Mean spherical equivalent changed from -1.45 diopters (D) to +0.52 (P<.00001). Total aberrations, HOAs, defocus, and spherical aberration improved significantly. No eye lost a line of BCVA; 4 eyes (28.6%) gained 1 line, and 1 eye (7.1%) gained 2 lines. Ten eyes (71.4%) were within 0.5 D of emmetropia. Four eyes were overcorrected by 1.00 to 2.00 D. Risk factors for overcorrection included increased HOAs, higher spherical aberration, and not using the surgeon's offset at the time of surgery.

CONCLUSIONS

Wavefront retreatment following conventional LASIK is safe and effective. Care must be taken when treating patients with higher amounts of total aberration, especially spherical aberration. Refractive results are closer to emmetropia when the surgeon's offset is used.

Effect of Optical Zone Ablation Diameter on LASIK-induced Higher Order Optical Aberrations

PURPOSE

To compare the postoperative higher order aberrations among eyes that had received conventional laser in situ keratomileusis (LASIK) treatment at different optical zone diameters using the Alcon LADARVision 4000 platform (Alcon, Ft Worth, Tex).

METHODS

Monochromatic wavefront aberrations at 6.5-mm pupil size of 96 eyes of 96 Hong Kong Chinese patients with normal myopic astigmatism were objectively measured using the Alcon LADARWave aberrometer before and after (at least 6 months) conventional LASIK with the Autonomous LADARVision 4000 excimer laser. Patients were divided into three groups according to optical zone diameter--group 1 (n=32), optical zone diameter <6.5 mm; group 2 (n=32), optical zone diameter 6.5 mm; and group 3 (n=32), optical zone diameter >6.5 mm).

RESULTS

Mean optical zone diameters of groups 1, 2, and 3 were 6.2+/-0.1 mm, 6.5+/-0.0 mm, and 6.9+/-0.2 mm, respectively. Total higher order, coma, and spherical aberrations before LASIK were 0.67+/-0.27 microm, 0.27+/-0.17 microm, and 0.41+/-0.14 microm in group 1; 0.56+/-0.26 microm, 0.28+/-0.15 microm, and 0.32+/-0.11 microm in group 2; and 0.62+/-0.25 microm, 0.34+/-0.15 microm, and 0.37+/-0.09 microm in group 3. After surgery, the aberrations increased to 1.20+/-0.21 microm, 0.71+/-0.25 microm, and 0.70+/-0.19 microm in group 1; 0.97+/-0.18 microm, 0.47+/-0.22 microm, and 0.69+/-0.13 microm in group 2; and 0.91+/-0.20 microm, 0.41+/-0.22 microm, and 0.56+/-0.12 microm in group 3. Compared to group 1, groups 2 and 3 had significantly less coma aberrations after LASIK (P=.03); the total high order aberration in group 3 was also significantly lower than in group 1 (P=.04) after treatment.

CONCLUSIONS

In conventional LASIK treatment using the Alcon LADARVision 4000 platform, a larger surgical optical zone diameter significantly decreases higher order aberrations after LASIK.

Higher Order Aberrations With Aspheric Ablations Using the Nidek EC-5000 CX II Laser

PURPOSE

To analyze the change in higher order aberrations in myopic and myopic astigmatic eyes following an aspheric ablation profile for laser in situ keratomileusis (LASIK) using a Nidek EC-5000 CX II excimer laser system.

METHODS

We performed a retrospective audit of 38 eyes (19 patients) with myopia and myopic astigmatism. A customized aspheric transition zone profile (CATz) was used in all eyes (profile 4) with an ablation zone of 5 mm and a transition zone of 9 mm using FinalFit software and a Nidek EC-5000 CX II excimer laser system.

RESULTS

Mean higher order aberrations (RMS) increased from 0.42 microm at baseline to 0.57 microm at 6-month follow-up. Mean spherical aberrations (Z12) increased from 0.02 microm at baseline to 0.33 microm after LASIK. Mean spherical aberration defocus equivalent (DEQ) increased from 0.56 microm at baseline to 1.54 at 6 months after surgery. Mean trefoil (Z6) was -0.11 microm at baseline and -0.14 microm at the 3-month examination. Mean coma (Z7) was -0.09 microm at baseline and -0.10 microm after surgery. Mean coma (Z8) was -0.03 at baseline and 0 at the 3-month examination. Mean trefoil (Z9) was -0.03 at baseline and -0.12 at the 3-month examination.

CONCLUSION

The amount of postoperative higher order aberrations in these myopic eyes was acceptable. However, the clinical significance of these numerical changes in aberrations is not known.

Correlation of Wavefront Data and Corneal Asphericity With Contrast Sensitivity After Laser in situ Keratomileusis for Myopia

PURPOSE

To investigate the relationship between contrast sensitivity (CS), Zernike wavefront aberrations (WFA), and asphericity after laser in situ keratomileusis (LASIK) for myopia.

METHODS

LASIK was performed using the Nidek EC-5000 excimer laser with custom aspheric transition zone (CATz) ablations. Total and high order (HO) WFA of 71 eyes (37 patients) undergoing LASIK in March 2003 were measured before and at 1 month postoperatively with the Nidek OPD-Scan aberrometer at a 4-mm pupil entrance; asphericity was measured at 6 mm (Q index). Preoperative and 1 to 3-month postoperative contrast sensitivity were evaluated with the Vector Vision CSV-1000 at 3, 6, 12, and 18 CPD; the Area Under the Log Contrast Sensitivity Function (AULCSF) was calculated. Uncorrected-visual acuity (UCVA) was evaluated.

RESULTS

One month after LASIK, CS decreased significantly at 6 CPD and above (P<.05), then returned to normal at 3 months (P=.33). Postoperative AULCSF correlated with patient age (P=.04) but not with total WFA (P=.13), HO WFA (P=.50), or asphericity (P=.22). Postoperative Logmar UCVA correlated with postoperative total and HO WFA (P<.05). Postoperative total WFA correlated with spherical equivalent refraction (P<.0001); HO WFA correlated with Strehl ratio (P=.004) and asphericity (P=.03). The HO WFA increase was 0.065 microm (P<.05) and did not correlate with preoperative refraction (P=.40). Increase in asphericity correlated with corneal refractive change and was predicted by the parabolic Munnerlyn equation (P<.0001).

CONCLUSIONS

After LASIK, AULCSF was not dependent on WFA, but mainly on patient age. WFA results correlated well with postoperative spherical equivalent refraction, asphericity, and Strehl ratio. These conclusions support a published hypothesis that postoperative low amount of WFA does not completely fit contrast sensitivity measurements.

Contralateral Comparison of Alcon CustomCornea and VISX CustomVue Wavefront-guided Laser in situ Keratomileusis: One-month Results

PURPOSE

To evaluate the differences in outcomes between CustomCornea and CustomVue LASIK treatments on different eyes of the same patient 1 month after surgery.

METHODS

Thirty-five patients were enrolled in two phases of a prospective study and treated with Alcon CustomCornea LASIK (Alcon Laboratories Inc, Fort Worth, Tex) on one eye and VISX CustomVue LASIK (VISX, Santa Clara, Calif) on the fellow eye. Twenty-five patients were treated in phase I without nomogram adjustments and ten patients were treated in phase II with nomogram adjustments made to the VISX CustomVue treatments only. Standard clinical outcomes such as visual acuity and manifest refraction were evaluated as well as quality of vision measures such as subjective questionnaires, contrast sensitivity, and higher order optical aberrations.

RESULTS

In the phase I group, 92% of the CustomCornea eyes and 72% of the CustomVue eyes were within 0.50 diopters (D) of their attempted correction. In the phase II group, with a nomogram applied to the CustomVue eyes, 80% of the CustomCornea eyes and 100% of the CustomVue eyes were within 0.50 D of their attempted correction. There was no loss of 22 lines of best spectacle-corrected acuity for the CustomCornea or CustomVue eyes in either phase I or phase II. Wavefront analysis demonstrated that the CustomVue eyes had statistically significantly more spherical aberrations at 1 month compared to the CustomCornea eyes in the phase I and II groups. An average increase in mesopic contrast sensitivity at spatial frequencies was seen for the CustomCornea eyes in phase II and in only one spatial frequency for the CustomVue eyes in phase II.

CONCLUSION

At 1 month after LASIK, the CustomCornea eyes showed superiority in the number of eyes seeing 20/20 or better uncorrected visual acuity, constrast sensitivity at 3 and 12 cpd, and the amount of postoperative spherical aberration. After nomogram adjustment, CustomVue eyes had a more accurate refractive outcome. Patients were satisfied or extremely satisfied with both systems, 92%-100%.

Wavefront-guided Treatment of Abnormal Eyes Using the LADARVision Platform

PURPOSE

To evaluate the clinical results of Alcon LADARVision4000 wavefront-guided customized treatment of eyes with myopia and/or astigmatism, and clinically significant visual symptoms related to the presence of higher order aberrations.

METHODS

Seven consecutive abnormal eyes from seven patients underwent wavefront-guided CustomCornea (1 PRK, 6 enhancements after previous LASIK) to correct low and higher order aberrations, using the Alcon LADARVision4000 platform. Eyes were examined at 1 to 3 months after treatment; the longest follow-up examination was used for analysis. Uncorrected and best spectacle-corrected visual acuity, manifest refractive spherical equivalent error, and subjective visual symptoms were measured, as well as wavefront measurement of higher order aberrations.

RESULTS

All seven eyes had an improvement in UCVA. One eye gained 2 lines of BSCVA, four eyes gained 1 line, and no eye lost any lines. Manifest refractive spherical equivalent error was slightly hyperopic in all eyes (+0.12 to +1.50 D). All eyes showed a reduction in pre-existing higher order aberrations, ranging between 1% and 48%. Spherical aberration was reduced most (mean 38% reduction), coma was reduced by a mean 14%, and all other terms were reduced by a mean 17% compared to preoperative values. Subjectively, all patients noticed a reduction in their pre-existing visual symptoms and reported visual performance comparable to their fellow asymptomatic eye. Overall, the treatment was considered very satisfactory by patients in terms of visual quality gain.

CONCLUSION

Wavefront-guided custom ablation with Alcon's LADARVision4000 was effective in reducing higher order aberrations and related visual symptoms in this preliminary small series. Longer follow-up on more eyes is necessary to assess the accuracy of the algorithm in the correction of defocus, which resulted in a slight overcorrection in this study.