A prospective randomized clinical trial of laser in situ keratomileusis with two different lasers

Anatomical and Visual Outcomes after LASIK Performed in Myopic Eyes with the WaveLight® Refractive Suite (Alcon® Laboratories Inc., USA)

Purpose

To evaluate changes in corneal anatomy and quality of vision following LASIK refractive surgery for mild to high myopia using the WaveLight® Refractive Suite (Alcon® Laboratories Inc., USA). Setting. Rothschild Foundation, Paris, France.

Design

Prospective interventional case series.

Methods

We examined 60 myopic eyes (average SE −4.5 D, from −9.3 to −0.75 D) of 30 patients from 21.3 to 38.7 years old. Pachymetry, keratometry, Q factor, corneal aberrations, visual acuity (VA), contrast sensitivity, dry eye assessment, and quality of vision were measured preoperatively, one day (D1), and 1, 3, and 6 months postoperatively.

Results

6 months postoperatively, keratometry became flatter, and the Q factor became more oblate (from −0.18 ± 0.08 to +0.19 ± 0.06). Pachymetry decreased by 117.9 ± 62.2 µm at D1 and increased by 37.87 ± 32.6 µm between D1 and M6. Refraction was emmetropic at D1 and remained stable thereafter. Six months after surgery, VA was slightly but nonsignificantly improved (<0.05 log MAR), whereas contrast sensitivity remained unchanged. Quality of vision was not affected by surgery and was more related to dry eye symptoms than to corneal HOAs (r² = 0.49; p < 0.001 vs. r² = 0.03; p < 0.001).

Conclusions

LASIK surgery for moderate to high myopia, performed with the WaveLight® Refractive Suite, showed good postoperative outcomes, with demonstrated safety, predictability, efficiency, and stability. This is probably due to well-controlled spherical aberration and the use of large optical zones. Besides, we can assume that the patients' quality of vision depends more on the postoperative dry eye disease generated by the laser than on the induced HOAs.

Myopic Laser-Assisted Subepithelial Keratectomy (LASEK) outcomes using three different excimer laser platforms: a retrospective observational study

Background

To compare the visual and refractive outcomes after myopic LASEK using three different excimer lasers and standardized surgical and mitomycin C (MMC) application protocols.

Methods

In this retrospective, observational cohort study, we examined 122 eyes treated with Allegretto, 135 eyes treated with Esiris and 137 eyes treated with Technolas excimer lasers. All eyes were treated under the same surgical protocol, and a standardized MMC dosage was used. The three groups were refraction-matched, and both visual and refractive outcomes were evaluated at 1 and 7 days and 1 and 3 months after surgery.

Results

At 3 months postsurgery, Allegretto provided significantly better outcomes than Esiris and Technolas in terms of postoperative uncorrected distance visual acuity (UDVA) (1.11 ± 0.2 vs 1.01 ± 0.2 vs 0.98 ± 0.2) (P = 0.0001), corrected distance visual acuity (CDVA) (1.13 ± 0.2 vs 1.10 ± 0.1 vs 1.04 ± 0.2) (P = 0.0001), residual sphere (− 0.01 ± 0.2 vs + 0.29 ± 0.7 vs + 0.27 ± 0.6) (P = 0.0001), and efficacy index (0.99 ± 0.2 vs 0.90 ± 0.2 vs 0.91 ± 0.2) (P = 0.0004).

Conclusions

We found slightly better visual and refractive outcomes in the Allegretto group at 3 months post-op after LASEK with MMC to correct myopia.

A Comparison of different scoring terminations rules for visual acuity testing: from a computer simulation to a clinical study

Purpose: To compare four visual acuity (VA) scoring termination rules. Methods: A computer simulation generated 30,000 virtual patients who underwent 10 repetitions for each of four termination rules, on both the Snellen and ETDRS charts (2.4 million tests performed in total). Three termination rules focused on the smallest character row: all characters were correctly identified (100%), one character was incorrectly identified (one miss) and 50% or more of the characters were correctly identified (50%). The forth termination rule used a calculation in which each character, when correctly recognized, contributed a proportional increment (per-letter). Accuracy, test-retest variability (TRV) and test duration were measured. Next, a clinical study was conducted in which 254 subjects underwent three repetitions of the ETDRS VA test from 4 m, and VA scores for each of the four scoring termination rules were calculated. Results: In the Snellen simulation, the mean accuracy of the 100%, one miss, 50% and per-letter termination rules in decimal was 0.23 (-0.16 logMAR), 0.11 (-0.09 logMAR), 0.10 (-0.08 logMAR), and -0.08 (0.08 logMAR) respectively; while with the ETDRS simulation, the mean accuracy in decimal was 0.34 (-0.22 logMAR), 0.14 (-0.11 logMAR), 0.07 (-0.06 logMAR), and 0.07 (-0.05 logMAR), respectively. For the ETDRS simulation, the per-letter had the lowest TRV values and the longest test duration. In the clinical study (n = 254), the reproducibility of the 100%, one miss, 50% and per-letter was 0.50, 0.53, 0.17, 0.14, respectively. Conclusions: Clinical study and simulation data both suggest that the 100% and one-miss termination rules have higher TRVs, while the 50% and per-letter demonstrated much tighter, and rather close, TRV values.

Importance of accurately assessing biomechanics of the cornea

PURPOSE OF REVIEW

This article summarizes the state-of-the-art in clinical corneal biomechanics, including procedures in which biomechanics play a role, and the clinical consequences in terms of error in estimating intraocular pressure (IOP).

RECENT FINDINGS

Corneal biomechanical response to refractive surgery can be categorized into either stable alteration of surface shape and thus visual outcome, or unstable biomechanical decompensation. The stable response is characterized by central flattening and peripheral steepening that is potentiated in a stiffer cornea. Two clinical devices for assessing corneal biomechanics do not yet measure classic biomechanical properties, but rather provide assessment of corneal deformation response. Biomechanical parameters are a function of IOP, and both the cornea and sclera become stiffer as IOP increases. Any assessment of biomechanical parameters must include IOP, and one value of stiffness does not adequately characterize a cornea.

SUMMARY

Corneal biomechanics plays a role in the outcomes of any procedure in which lamellae are transected. Once the corneal structure has been altered in a manner that includes central thinning, IOP measurements with applanation tonometry are likely not valid, and other technologies should be used.

Refractive Outcomes, Contrast Sensitivity, HOAs, and Patient Satisfaction in Moderate Myopia: Wavefront-Optimized Versus Tissue-Saving PRK

PURPOSE

To compare refractive outcomes, contrast sensitivity, higher-order aberrations (HOAs), and patient satisfaction after photorefractive keratectomy for correction of moderate myopia with two methods: tissue saving versus wavefront optimized.

METHODS

In this prospective, comparative study, 152 eyes (80 patients) with moderate myopia with and without astigmatism were randomly divided into two groups: the tissue-saving group (Technolas 217z Zyoptix laser; Bausch & Lomb, Rochester, NY) (76 eyes of 39 patients) or the wavefront-optimized group (WaveLight Allegretto Wave Eye-Q laser; Alcon Laboratories, Inc., Fort Worth, TX) (76 eyes of 41 patients). Preoperative and 3-month postoperative refractive outcomes, contrast sensitivity, HOAs, and patient satisfaction were compared between the two groups.

RESULTS

The mean spherical equivalent was -4.50 ± 1.02 diopters. No statistically significant differences were detected between the groups in terms of uncorrected and corrected distance visual acuity and spherical equivalent preoperatively and 3 months postoperatively. No statistically significant differences were seen in the amount of preoperative to postoperative contrast sensitivity changes between the two groups in photopic and mesopic conditions. HOAs and Q factor increased in both groups postoperatively (P = .001), with the tissue-saving method causing more increases in HOAs (P = .007) and Q factor (P = .039). Patient satisfaction was comparable between both groups.

CONCLUSIONS

Both platforms were effective in correcting moderate myopia with or without astigmatism. No difference in refractive outcome, contrast sensitivity changes, and patient satisfaction between the groups was observed. Postoperatively, the tissue-saving method caused a higher increase in HOAs and Q factor compared to the wavefront-optimized method, which could be due to larger optical zone sizes in the tissue-saving group.

Visual outcome and contrast sensitivity after photorefractive keratectomy in low to moderate myopia: wavefront-optimized versus conventional methods

PURPOSE

To compare visual outcomes and contrast sensitivity after wavefront-optimized or conventional photorefractive keratectomy (PRK) in myopic patients with or without astigmatism.

SETTING

Vanak Eye Surgery Center, Tehran, Iran.

DESIGN

Comparative case series.

METHODS

Patients with low to moderate myopia with or without astigmatism were allocated into 2 groups. The study group was treated with wavefront-optimized PRK (Allegretto Wave Eye-Q software version 2.020 default treatment) and the control group, with conventional PRK (Technolas 217z). In all cases, treatments were bilateral and performed with the same device. Baseline and 3-month postoperative measures were uncorrected and corrected distance visual acuities, manifest refraction, and contrast sensitivity.

RESULTS

Each group comprised 66 eyes. The mean preoperative spherical equivalent refraction improved from -2.99 diopters (D) ± 1.02 (SD) preoperatively to -0.08 ± 0.26 D 3 months postoperatively in the study group and from -2.66 ± 0.95 D to 0.01 ± 0.30 D, respectively, in the control group. In both groups, the postoperative mesopic and photopic contrast sensitivity decreased significantly at most spatial frequencies. The postoperative decrease in contrast sensitivity in both groups was comparable except at spatial frequencies of 3 cycles per degree (cpd) under mesopic conditions and 12 cpd under photopic conditions, frequencies at which the control group had a greater reduction.

CONCLUSIONS

Visual acuity and refractive error outcomes were similar in both treatment groups. After 3 months, mesopic and photopic contrast sensitivity were significantly decreased in both groups; the reduction in the 2 groups was almost comparable.

FINANCIAL DISCLOSURE

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

Efficacy, predictability, and safety of wavefront-guided refractive laser treatment: metaanalysis

PURPOSE

To compare the efficacy, predictability, safety, and induced higher-order aberrations (HOAs) between wavefront-guided and non-wavefront-guided ablations.

SETTING

Division of Ophthalmology and Visual Sciences, University of Nottingham, Nottingham, United Kingdom.

DESIGN

Metaanalysis.

METHODS

The Cochrane Central Register of Controlled Trials, PubMED, and EMBASE were searched for randomized controlled trails. Trials meeting the selection criteria were quality appraised and data extracted by 2 independent authors. Measures of association were pooled quantitatively using metaanalytical methods. Comparison between wavefront-guided and non-wavefront-guided ablations was measured as pooled odds ratios (ORs) or weighted mean differences. The pooled ORs and 95% confidence intervals (CIs) were computed for efficacy, safety, and predictability. The weighted mean difference and 95% CIs were used to compare induced HOAs.

RESULTS

Eight trials involving 955 eyes were included. After wavefront-guided LASIK, the pooled OR of achieving uncorrected distance visual acuity (UDVA) of 20/20 (efficacy) was 1.10 (95% CI, 0.66-1.83; P=.72), the pooled OR of achieving a result within ± 0.50 diopter of intended target (predictability) was 1.03 (95% CI, 0.60-1.75; P=.92), and the weighted mean difference in induced HOAs was -0.09 (95% CI, -0.17 to -0.01; P=.04). No study reported loss of 2 or more lines of Snellen acuity (safety) with either modality.

CONCLUSIONS

Metaanalysis showed no clear evidence of a benefit of wavefront-guided over non-wavefront-guided ablations. However, there was a lack of standardized reporting of UDVA better than 20/20, which might mask an advantage in wavefront-guided treatment. With high preexisting HOAs, wavefront-guided has advantages over non-wavefront-guided treatment.

Visual and non-visual factors associated with patient satisfaction and quality of life in LASIK

PURPOSE

The aim of this study was to determine how laser in situ keratomileusis (LASIK) affects quality of life (QOL) and to identify factors that may affect satisfaction after LASIK.

METHODS

A total of 104 patients with a mean age of 29±6, treated with LASIK for myopia and astigmatism, were enrolled in a prospective study. High (90%) and low (10%) contrast visual acuity (CVA) were measured under photopic and scotopic conditions before surgery and at 3 months later. A multidimensional QOL scale (Institute for Eye Research multidimensional QOL scale), which assesses psychological characteristics, personality traits, cosmesis, frequency, and tolerance to disturbing visual and ocular symptoms, and overall satisfaction with vision correction, was also used. Paired rank tests were used to compare preoperative and postoperative vision and QOL scores. Correlations and a multiple linear regression were used to describe the relationship between CVA, QOL, and satisfaction after LASIK.

RESULTS

Significant postoperative changes included increased satisfaction following LASIK (P<0.001), reduced frequency of visual and ocular symptoms (P<0.001), and change in psychological characteristics (P=0.033). The change in satisfaction with LASIK can be predicted by a combination of preoperative satisfaction, postoperative frequency of disturbing visual and ocular symptoms, postoperative mean spherical equivalent, and postoperative scotopic high CVA (R (2)=0.725, P<0.05).

CONCLUSIONS

Satisfaction with LASIK is related to visual function, preoperative expectations, psychological characteristics, and uncorrected CVA achieved. An increased sense of subjective well-being, adaptability, and self-efficacy was evident after LASIK. Patients reported a more optimistic attitude to life and increase perceived QOL after surgery.

Comparison of the topographic ablation zone after photorefractive keratectomy for myopia using two different excimer lasers

PURPOSE

To compare the topographic features of eyes treated with photorefractive keratectomy (PRK) for myopia using two different excimer lasers.

METHODS

A total of 65 eyes in 39 patients treated with PRK (6.0-mm optical zone) using Technolas 217C and VISX S4 excimer lasers were evaluated retrospectively to determine the size of the topographic ablation zone.

RESULTS

The zones ablated using the VISX S4 had shorter diameters in both axes (-0.89+/-0.73, -1.59+/-0.49 mm; both P=0.00), whereas those ablated using the Technolas 217C had a longer diameter in the major axis (0.96+/-0.63 mm; P=0.00) and a shorter diameter in the minor axis (-0.39+/-0.59 mm; P=0.00). The theoretical ablated zone was a circle with a diameter of 6.0 mm. The Technolas 217C group tended to have oval cuts in comparison with the VISX S4 group, and the difference between the programmed (6.0 mm) and topographic diameters was significant in both groups.

CONCLUSIONS

There was a difference between the programmed and postoperative topographic diameters of the ablation zone. The postoperative ablation zone differed in shape and size according to the type of excimer laser.

LASIK world literature review: quality of life and patient satisfaction

PURPOSE

To analyze the patient reported outcome of satisfaction after LASIK surgery.

DESIGN

Systematic review.

PARTICIPANTS

Patient data from previously reported studies.

METHODS

A literature search conducted for the years 1988 to 2008 that included pertinent LASIK surgery information from the review of 2915 retrieved citations. All abstracts from these citations were reviewed and 1581 were deemed to be relevant for review. Complete copies of each of these relevant (1581) articles were obtained, and after thorough analysis each was rated based on the strength of the study design and weight of evidence. A level I rating was assigned to properly conducted, well-designed, randomized clinical trials; a level II rating to well-designed cohort and case-control studies; and a level III rating to case series, case reports, and poorly designed prospective and retrospective studies. Level I and II rated, peer-reviewed articles were entered into a database, and level III articles were eliminated. A total of 309 articles were incorporated into this database, representing level I and level II well-controlled studies of primary LASIK surgery.

MAIN OUTCOME MEASURES

Patients' satisfaction rates and factors associated with dissatisfaction.

RESULTS

Nineteen of the 309 database articles (6.1%) reported on both patient quality of life and satisfaction and together encompassed a total of 2198 subjects. The procedures from these 19 articles took place between 1995 and 2003. The overall patient satisfaction rate after primary LASIK surgery was 95.4% (2097 of 2198 subjects; range of patient satisfaction for the 19 articles was 87.2%-100%). The patient satisfaction rate after myopic LASIK was 95.3% (1811 of 1901 patients), and after hyperopic LASIK was 96.3% (286 of 297 subjects).

CONCLUSIONS

Based on this review, worldwide, an average 95.4% of patients were satisfied with their outcome after LASIK surgery. With 16.3 million procedures performed worldwide, and more than a decade of clinical studies and technological innovation, LASIK surgery should be considered among the most successful elective procedures. LASIK surgery compares more favorably with other elective surgical procedures in terms of generally higher satisfaction rates.

Prospective randomized trial of wavefront-guided laser in situ keratomileusis with the CustomCornea and CustomVue laser systems

PURPOSE

To compare visual function, safety, and higher-order aberrations (HOAs) after wavefront-guided laser in situ keratomileusis (LASIK) with the LadarVision CustomCornea (Alcon Laboratories, Inc.) and Star S4 CustomVue (Visx) laser systems.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

Seventy-eight eyes of 39 patients with myopia with or without astigmatism were randomized for LASIK treatment in 1 eye with the CustomCornea laser; the other eye was treated with the CustomVue laser. Patients were followed for 6 months after surgery. The primary outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and changes in HOAs.

RESULTS

At 6 months, the mean logarithm of the minimum angle of resolution (logMAR) UCVA was -0.0135 +/- 0.07 (SD) in the CustomVue group and 0.0417 +/- 0.12 in the CustomCornea group (P = .023). Eighty-eight percent of eyes in the CustomVue group had 20/20 or better UCVA compared with 67% in the CustomCornea group (P<.02). At 6 months, 91% of eyes in the CustomVue group and 79% in the CustomCornea group were within +/-0.50 diopter (D) of emmetropia (P<.1); 88% and 50%, respectively, were within +/-0.25 D (P<.001). Both platforms led to a small increase in total HOAs. The CustomVue system reduced trefoil and induced less of an increase in total HOAs, whereas the CustomCornea platform increased trefoil but induced less of an increase in spherical aberrations and coma.

CONCLUSIONS

Both laser systems were effective, safe, and predictable. Wavefront-guided LASIK with the CustomVue system resulted in better visual acuity, with more eyes having 20/20 acuity than in the CustomCornea group.

Retrospective comparison of 3 laser platforms to correct myopic spheres and spherocylinders using conventional and wavefront-guided treatments

PURPOSE

To compare 3 excimer laser platforms for the correction of myopic spheres and myopic spherocylinders using conventional algorithms or wavefront-guided treatments.

SETTING

Private practice, in-office laser facility.

METHODS

This retrospective comparative interventional case series comprised 458 patients (721 eyes). Sequentially selected patient eyes had laser in situ keratomileusis surgery by the same surgeon using 1 of 3 lasers (Visx Star S4, LADARVision 4000, WaveLight Allegretto) with a conventional algorithm or with wavefront-guided software. The same aberrometer was used before and after surgery in a given eye. A femtosecond laser (IntraLase Corp.) was used for flap creation. Parametric and nonparametric 1-way analysis of variance and regression analysis were performed. Outcomes were analyzed for change in visual, refractive, and wavefront categories.

RESULTS

On average, all lasers improved uncorrected visual acuity and best spectacle-corrected visual acuity, produced predictable refractive change, and induced higher-order aberrations (HOAs). Overall, the Star S4 wavefront treatment improved results compared with Star S4 conventional treatment; however, LADARVision wavefront treatment did not improve the conventional results. The Allegretto produced the best results in the category of visual acuity in spherocylinder eyes only. The Star S4 wavefront treatment produced the best HOA results for sphere and spherocylinder. In the spherocylinder group, the LADARVision reduced astigmatism and defocus the most.

CONCLUSION

These results document that different laser platforms achieve statistically significantly different outcomes depending on refractive, patient, and surgical variables.

Matched Population Comparison of the Visian Implantable Collamer Lens and Standard LASIK for Myopia of -3.00 to -7.88 Diopters

PURPOSE

To compare matched populations of LASIK and Visian Implantable Collamer Lens (ICL) cases in the correction of myopia between -3.00 and -7.88 diopters (D).

METHODS

One hundred sixty-four LASIK eyes with prospective data collected from a single center and 164 ICL eyes from the multicenter US ICL Clinical Trial were compared in this observational non-randomized study. The LASIK and ICL groups were well matched for age, gender, and mean level of preoperative spherical equivalent refraction.

RESULTS

At 6 months, best spectacle-corrected visual acuity (BSCVA) > or = 20/20 was 85% with LASIK and 95% with ICL (P = .003) compared to preoperative values of 93% and 88%, respectively (P = .292). Loss of > or = 2 lines of BSCVA was significantly lower with the ICL at 1 week (0.6% vs 10%, P < .001) and 1 month (7% vs 0%, P = .001) with comparable outcomes at 6 months (0% vs 1%). At 6 months postoperatively, uncorrected visual acuity (UCVA) > or = 20/15 (11% vs 25%, P = .001) and > or = 20/20 (49% vs 63%, P = .001) was better in the ICL cases. Predictability within 0.50 D at 6 months for ICL cases was 85% (67% LASIK, P < .001); 97% of ICL cases were within 1.00 D (88% LASIK, P = .002). Refractive stability (+/- 0.50 D) between 1 and 6 months was 93% with ICL compared to only 82% with LASIK (P = .006).

CONCLUSIONS

The ICL performed better than LASIK in almost all measures of safety, efficacy, predictability, and stability in this matched population comparison, supporting the ICL as an effective alternative to existing refractive laser surgical treatments for the range of myopia studied.

Sensitivity of the National Eye Institute Refractive Error Quality of Life instrument to refractive surgery outcomes

PURPOSE

To evaluate scores from the National Eye Institute Refractive Error Quality of Life instrument (NEI-RQL) relative to refractive surgery outcomes in myopic patients.

SETTING

Large institutional ophthalmic practices.

METHODS

Patients seeking refractive surgery (n = 59) self-administered the NEI-RQL before and 6 months after surgery; the comparison group of myopes and emmetropes (n = 72) not seeking refractive surgery also completed the NEI-RQL. Myopic patients seeking refractive surgery had bilateral, same-day laser in situ keratomileusis (LASIK) treatment. Regression analyses were conducted to compare survey scores in the LASIK treatment group before surgery with those in the myopic sample who were not seeking refractive surgery and to compare the survey scores in the post-LASIK treatment group (surgical emmetropes) to those in the naturally emmetropic group. Logistic regression was used to determine NEI-RQL subscales that were related to myopic patients seeking refractive surgery and myopic patients not seeking refractive surgery.

RESULTS

Myopes seeking LASIK reported greater expectations for vision improvement (P < .0001), greater activity limitations (P < .0001), suboptimal correction (P = .04), worse appearance (P < .0001), and lower satisfaction (P < .0001) than myopes not seeking refractive surgery. Logistic regression showed that worse self-perceived appearance (odds ratio 20.71), more dissatisfaction with current correction (odds ratio 8.28), and higher expectations for "optimal" correction (odds ratio 6.41) were independently associated with myopes seeking LASIK, while better perceived "clarity of vision" (odds ratio = 0.20) was associated with myopes not seeking surgery. Overall, surgical emmetropes were similar to natural emmetropes in terms of refractive-error-specific quality of life (clarity of vision, near vision, far vision, diurnal fluctuations) and clinical measures of visual function, yet they reported significantly better appearance (P = .02) and greater satisfaction (P < .0001) than natural emmetropes.

CONCLUSION

The NEI-RQL demonstrated vision-related quality-of-life differences when comparing patient samples associated with refractive surgery.