A comprehensive review on corneal crosslinking

Corneal crosslinking (CXL) represents a paradigm shift in the management of corneal ectatic disorders. Before CXL was introduced, patients would need specialty contact lenses and possible corneal transplantation. CXL involves a biochemical reaction in which ultraviolet A light is used in conjunction with Riboflavin to form crosslinks in between corneal stromal collagen. This leads to strengthening and stabilizing of the collagen lamellae, resulting in mechanical stiffening of the cornea. Multiple protocols have been proposed including epithelium on versus off and varying light intensity and duration of treatment. All protocols appear to be safe and effective with few reported complications including infection, stromal haze, scarring, and endothelial toxicity. Overall, CXL has demonstrated to halt the progression of the disease clinically and in keratometry readings and improve the quality of life for patients. It is a minimally invasive, cost-effective procedure that can be performed in an outpatient setting with a fast recovery time and long-lasting results.

Patient-reported quality of vision in a prospective randomized contralateral-eye trial comparing LASIK and small-incision lenticule extraction

PURPOSE

To compare patient-reported quality of vision and visual symptoms in participants undergoing laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE).

SETTING

Byers Eye Institute, Stanford University, Palo Alto, California.

DESIGN

Prospective randomized contralateral-eye clinical trial.

METHODS

Patients with myopia were randomized to receive wavefront-guided femtosecond LASIK in one eye and SMILE in the fellow eye. Participants reported the presence and severity of adverse visual symptoms through the Patient-Reported Outcomes With Laser In Situ Keratomileusis questionnaire and reported which eye had better vision at the preoperative and the postoperative 1-month, 3-month, 6-month, and 12-month visits.

RESULTS

80 eyes of 40 participants were treated. There was no difference in the presence or severity of double vision, glare, halos, or starbursts between eyes that underwent LASIK or SMILE at each visit ( P ≥ .85 for each comparison). Scaled scores for the presence of visual symptoms improved from the preoperative visit to the postoperative month 12 visit for double vision (88 vs 97, P = .03), glare (77 vs 92, P = .02), halos (68 vs 87, P < .01), and starbursts (60 vs 86, P < .01). At the postoperative month 12 visit, 17 (46%) of 37 participants preferred the vision from the eye that underwent LASIK compared with 7 (19%) of 37 who underwent SMILE. The preferred eye was correlated with uncorrected distance visual acuity ( r = 0.52, P < .01).

CONCLUSIONS

Rates of visual symptoms were similar for LASIK and SMILE, and visual symptoms improved with time. More patients preferred vision from the eye that underwent LASIK compared with SMILE.

Subjective visual experience and ocular symptoms after wavefront-guided and wavefront-optimized LASIK in a prospective fellow eye study

PURPOSE

The purpose of this study was to compare the subjective visual experience and ocular symptoms of fellow eyes treated with wavefront-optimized (WFO-) laser-assisted in situ keratomileusis (LASIK) and wavefront-guided (WFG-) LASIK.

DESIGN

Prospective randomized fellow eye, controlled study.

METHODS

Two hundred eyes of 100 subjects from a single academic center were enrolled and randomly assigned to treatment with WFO-LASIK in one eye and WFG-LASIK in the fellow eye. Subjects filled out a validated 14-part questionnaire for each eye at the preoperative visit and at postoperative months 1,3,6,12.

RESULTS

In comparing the number of subjects who reported symptoms in the WFG- vs WFO- LASIK eyes, there was no difference in number reporting any visual experience (glare, halos, starbursts, hazy vision, blurred vision, distortion, double or multiple images, fluctuations in vision, focusing difficulties, and depth perception; all p>0.05) or ocular symptoms (photosensitivity, dry eye, foreign body sensation, ocular pain; all p>0.05). There was no preference for WFG-LASIK (28%) or the WFO-LASIK treated eye (29%) with most subjects reporting no preference (43%; Chi-squared p=0.972). Of the subjects who preferred one eye or the other, the preferred eye saw statistically better than the fellow eye (0.8 ± 1.4 Snellen line, p=0.0002). There was no other difference in subjective visual experience, ocular symptoms, refractive characteristics when taking into account eye preference.

CONCLUSIONS

Most subjects had no eye preference; and for subjects who did have eye preference, the only detectable difference was better visual acuity in the preferred eye.

Patient-Reported Outcomes With Wavefront-Guided Laser in Situ Keratomileusis (PROWL) Study Outcomes From a Single Institution

PURPOSE

To determine patient-reported outcomes after laser in situ keratomileusis (LASIK) using wavefront-guided technology at a single institution.

METHODS

In this prospective observational study, 62 participants underwent examination and questionnaire at baseline, 1 month, and 3 months after surgery. The questionnaire included questions from validated questionnaires and new items to assess patient satisfaction with current vision and LASIK surgery, and existence/degree of visual symptoms.

RESULTS

At month 1, patients reported an improvement in far vision (P = .01), activity limitations (P ≤ .001), and less worry about vision (P ≤ .001), as well as new visual symptoms, including halos (P ≤ .001) and double images (P = .03). At month 3, patients still noted an improvement in near vision (P = .05), far vision (P ≤ .001), activity limitation (P ≤ .001), and worry (P ≤ .001) along with halos (P = .05), double images (P = .01), and dry eye (P = .01). A total of 3.3% of patients at month 1 and 0% at month 3 had difficulty performing any activity due to symptoms, and 34.6% and 25.0% of patients reported decreased quality of life at months 1 and 3, respectively.

CONCLUSIONS

After LASIK, patients experience new visual symptoms. Patients have high rates of satisfaction overall but with some patients reporting a decrease in quality of life 1 month after surgery; quality of life improves by postoperative month 3, with 25% patients reporting a decrease in visual well-being after surgery. [J Refract Surg. 2023;39(3):198-204.].

Effect of corneal epithelial remodeling on visual outcomes of topography-guided femtosecond LASIK

PURPOSE

To assess the effect of epithelial remodeling on visual outcomes over a 9 mm diameter corneal surface after topography-guided laser in situ keratomileusis (LASIK) for myopia correction using spectral-domain anterior segment optical coherence tomography (AS-OCT).

SETTING

Outpatient clinical practice at the Stanford University Byers Eye Institute in Palo Alto, California.

DESIGN

Prospective nonrandomized observational study.

METHODS

Visual acuity, including uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), 5% and 25% contrast sensitivity CDVA, manifest refraction, and corneal epithelial thickness after topography-guided femtosecond LASIK were analyzed. Corneal epithelial thickness was mapped across 13 sections and 3 concentric zones using AS-OCT preoperatively and at 1 month, 3 months, 6 months, and 12 months postoperatively.

RESULTS

60 eyes of 30 patients with a mean age of 32.8 years (range 23 to 52 ± 7.03 years) undergoing myopic LASIK correction were assessed. In eyes with complete follow-up data (n = 30), mean preoperative UDVA was logMAR 1.48 ± 0.45 and logMAR -0.11 ± 0.08 at postoperative 12 months. Mean preoperative CDVA was logMAR -0.08 ± 0.11 and logMAR -0.13 ± 0.07 at 12 months. Linear mixed modeling demonstrated a significant correlation between improvement in UDVA and decreased superior and nasal corneal epithelial thickness and between improvement in CDVA and increased central epithelial thickness 12 months postoperatively.

CONCLUSIONS

Improvement in UDVA and CDVA at 12 months after topography-guided femtosecond LASIK was correlated with nonuniform epithelial remodeling, including epithelial thickening in the central zone and thinning in the superior and nasal sections as measured by AS-OCT.

Prospective, Randomized Contralateral Eye Comparison of Wavefront-Guided Laser In Situ Keratomileusis and Small Incision Lenticule Extraction Refractive Surgeries

PURPOSE

Wavefront-guided laser in situ keratomileusis (WFG-LASIK) and small incision lenticule extraction (SMILE) are keratorefractive surgeries that can improve uncorrected visual acuity in myopic patients. Comparison of visual outcomes in myopic patients treated with LASIK and SMILE is needed.

DESIGN

Prospective, randomized contralateral eye-controlled trial.

METHODS

We performed a single-center prospective, randomized contralateral eye comparison of WFG-LASIK and SMILE (NCT03067077). Myopic patients with low levels of astigmatism were treated with WFG-LASIK in one eye and SMILE in the fellow eye from March 2017 to March 2021. Treatments were randomized by ocular dominance. WFG-LASIK and SMILE were performed. Postoperative evaluation at 1 day consisted of uncorrected distance visual acuity (UDVA), wavefront aberrometry, and a slit-lamp examination. On subsequent postoperative visits at 1 month, 3 months, 6 months, and 12 months, UDVA, manifest refraction, 5% and 25% low-contrast visual acuity, wavefront aberrometry, and slit-lamp examination were performed.

MAIN OUTCOME MEASURE

The primary outcome measure was UDVA at 12 months.

RESULTS

Eighty-eight eyes of 44 patients with myopia were enrolled in the study. Seventy-four eyes of 37 patients had successful treatments and completed 12 months of follow-up. At postoperative month 12, there were a significantly higher proportion of WFG-LASIK eyes that had ≥20/20 UDVA compared with SMILE eyes (94% vs 83%, P < .05). There was no difference between spherical equivalent between WFG-LASIK eyes and SMILE eyes (-0.17 ± 0.25 vs -0.29 ± 0.38, P > .05); there was no difference in higher order aberrations, including coma, trefoil, and spherical aberrations (P > 0.05); and there were a significantly higher proportion of WFG-LASIK eyes that had improved 5% and 25% low-contrast visual acuity compared with SMILE eyes (P < 0.05).

CONCLUSIONS

WFG-LASIK and SMILE both offered marked improvements in corrected distance visual acuity and excellent predictability in both eyes. Compared with SMILE, WFG-LASIK resulted in faster visual recovery, better low-contrast visual acuity, and greater gains in uncorrected visual acuity.

Outcomes After Corneal Crosslinking for Keratoconus in Children and Young Adults

PURPOSE

The aim of this study was to assess the effect of corneal crosslinking on vision and keratometry in children and young adults with progressive keratoconus.

METHODS

A retrospective medical records review of patients aged 22 years or younger with keratoconus who underwent corneal crosslinking between January 2013 and November 2019 at Byers Eye Institute at Stanford University was conducted. Outcome measures included logarithm of the Minimum Angle of Resolution corrected distance visual acuity (CDVA); keratometry, including maximum keratometry (Kmax); pachymetry; and total wavefront aberration. Measurements were taken at baseline and at 12 and 24 months postoperatively.

RESULTS

Fifty-seven eyes of 49 patients aged 12 to 22 years were assessed. The mean preoperative CDVA was logarithm of the Minimum Angle of Resolution 0.38 ± 0.32 (20/48), with a mean postoperative CDVA of 0.29 ± 0.31 (20/39) and 0.31 ± 0.31 (20/41) at 12 and 24 months postoperatively, respectively. Compared with preoperative mean Kmax, there was an improvement of -0.8 diopters (D) to a mean postoperative Kmax of 59.1 ± 9.1 D at 12 months and -1.3 D to 59.7 ± 8.8 D at 24 months. Subanalysis excluding the second eye of patients who underwent bilateral crosslinking showed similar results. Linear mixed modeling showed significant improvement in Kmax at both 12 and 24 months postoperatively. Minimum central corneal thickness initially decreased but stabilized at 24 months after crosslinking. Total wavefront aberration remained stable.

CONCLUSIONS

Corneal crosslinking stabilizes, and in some cases improves, visual and corneal parameters in pediatric and young adult patients with keratoconus. The procedure is safe and well-tolerated and may prevent keratoconus progression in young patients.

Drug delivery to the anterior segment of the eye: A review of current and future treatment strategies

Research in the development of ophthalmic drug formulations and innovative technologies over the past few decades has been directed at improving the penetration of medications delivered to the eye. Currently, approximately 90% of all ophthalmic drug formulations (e.g. liposomes, micelles) are applied as eye drops. The major challenge of topical eye drops is low bioavailability, need for frequent instillation due to the short half-life, poor drug solubility, and potential side effects. Recent research has been focused on improving topical drug delivery devices by increasing ocular residence time, overcoming physiological and anatomical barriers, and developing medical devices and drug formulations to increase the duration of action of the active drugs. Researchers have developed innovative technologies and formulations ranging from sub-micron to macroscopic size such as prodrugs, enhancers, mucus-penetrating particles (MPPs), therapeutic contact lenses, and collagen corneal shields. Another approach towards the development of effective topical drug delivery is embedding therapeutic formulations in microdevices designed for sustained release of the active drugs. The goal is to optimize the delivery of ophthalmic medications by achieving high drug concentration with prolonged duration of action that is convenient for patients to administer.

A Prospective Comparison of Wavefront-Guided LASIK versus Wavefront-Guided PRK After Previous Keratorefractive Surgery

Purpose

To compare the results of retreatment with wavefront-guided LASIK versus wavefront-guided PRK for residual refractive error following previous myopic keratorefractive surgery.

Methods

In this prospective study, 32 eyes of 28 patients after prior myopic keratorefractive surgery underwent retreatment with flap-lift wavefront-guided LASIK (n = 12) or wavefront-guided PRK (n = 20) for residual refractive error. Safety, efficacy, predictability, and wavefront outcomes were evaluated.

Results

At last follow-up, both LASIK and PRK retreatment resulted in similar improvement in visual acuity with respective mean ± standard deviation (SD) uncorrected distance visual acuity of −0.07 ± 0.11 logMAR and −0.06 ± 0.13 logMAR (p = 0.87). In the study, 16.7% of LASIK and 33.3% of PRK eyes gained one or more lines of best-corrected distance visual acuity (CDVA), while 16.7% and 9.5% of eyes lost one or more lines of CDVA with LASIK and PRK, respectively. One hundred % of LASIK eyes and 89.5% of PRK eyes were within ± 0.50 diopters of emmetropia. Wavefront analysis demonstrated similar reductions in total RMS error higher-order aberrations (p = 0.84) with no difference in coma, trefoil, or spherical aberration between eyes undergoing LASIK or PRK retreatment.

Conclusion

Wavefront-guided LASIK and wavefront-guided PRK following previous keratorefractive surgery demonstrate similar safety, efficacy, and predictability with comparable wavefront outcomes.

One-Year Outcomes From a Prospective, Randomized, Eye-to-Eye Comparison of Wavefront-Guided and Wavefront-Optimized PRK in Myopia

PURPOSE

To compare wavefront-guided (WFG) and wavefront-optimized (WFO) photorefractive keratectomy (PRK) in patients with myopia using objective and self-reported quality of vision outcomes.

METHODS

A total of 40 eyes from 20 participants were prospectively randomized to receive WFG or WFO PRK with the WaveLight Allegretto Eye-Q 400-Hz excimer laser (Alcon Laboratories, Inc., Fort Worth, TX). The primary outcome measured was uncorrected distance visual acuity (UDVA) at 12 months postoperatively. Secondary outcome measures included corrected distance visual acuity (CDVA), less than 5% and less than 25% contrast visual acuity, changes in higher order aberrations (HOAs), and self-reported quality of vision. Patients completed a validated, Rasch-tested, linear-scaled 30-item questionnaire assessing the quality of vision and visual symptoms preoperatively and at each visit.

RESULTS

There was no statistically significant difference (P > .05) between the WFG and WFO groups in the frequency of attaining a refractive error within ±0.25 diopters of emmetropia, achieving postoperative UDVA of 20/16 or better or 20/20 or better, losing one or two or more lines or maintaining their preoperative CDVA, or differences in UDVA, CDVA, low contrast acuity, or HOAs. None of the measured quality of vision parameters exhibited statistically significant differences between the groups preoperatively or at 12 months postoperatively (all P > .05). The WFG and WFO groups each showed significant improvement in multiple subjective measures compared to pretreatment values in the same eye. A total of 12.5% of patients preferred their WFG PRK eye, 31.25% preferred their WFO PRK eye, and 56.25% had no preference at 12 months postoperatively.

CONCLUSIONS

WFG and WFO PRK using the Alcon Wave-Light Allegretto Eye-Q 400-Hz excimer laser platform provide similar results and self-reported visual symptoms in myopic eyes at 12 months postoperatively. [J Refract Surg. 2020;36(3):160-168.].

Prospective, Randomized, Contralateral Eye Comparison of Wavefront-Guided and Wavefront-Optimized Laser in Situ Keratomileusis

PURPOSE

To compare outcomes in wavefront-optimized (WFO) laser in situ keratomileusis (LASIK) to high-resolution wavefront-guided (WFG) LASIK.

DESIGN

Randomized, fellow eye controlled, clinical trial.

METHODS

A total of 200 eyes of 100 patients with myopia or compound myopic astigmatism undergoing bilateral LASIK between October 2015 and February 2017 underwent wavefront-optimized (WFO) LASIK in 1 eye and wavefront-guided (WFG) LASIK in the fellow eye. Each eye was evaluated for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), contrast sensitivity, refractive error, and wavefront aberrometry. Outcome measurement primarily UDVA at 12 months. Secondary outcomes were safety, predictability, stability, refractive error, CDVA, contrast sensitivity, and higher-order aberrations at 12 months.

RESULTS

WFG LASIK had higher levels of supervision and better contrast sensitivity compared to WFO. Both types had excellent postoperative UDVA results, without a significant difference in either mean UDVA or frequency of achieving a specified UDVA, for example, 20/16 or better (all P > 0.05). The mean gain in lines of CDVA was significantly higher in the WFG than in the WFO group (0.80 ± 0.75 vs 0.62 ± 0.72, respectively; P = 0.04). The WFG cohort had significantly better contrast sensitivity for mean and frequency of achieving >20/40 for <5% low-contrast sensitivity (37.1%; 95% confidence interval [CI], 27.5-46.7 vs 24.7%; 95% CI, 16.2-33.3, respectively; P = 0.01) and >20/32 for <25% low-contrast sensitivity (10.3%; 95% CI, 4.3-16.4 vs 4%, respectively; 95% CI, 0.0-8.1, respectively; P = 0.04). The WFO group had a significantly higher frequency of <0.25 diopters (D) of refractive astigmatism at 12 months (82.5%; 95% CI, 75.0-90.0; vs 72.1%, respectively; 95% CI, 63.2-81.2; P = 0.02) but not <0.50 D (95.6%; 95% CI, 91.9-99.8; vs 96.9, respectively; 95% CI, 93.5-100; P = 0.61). The WFG group was significantly closer to emmetropia for both sphere and spherical equivalents at all time points. Trefoil was significantly lower in the WFG group and was also significantly lower than preoperative measurements.

CONCLUSIONS

Wavefront-optimized and high-resolution wavefront-guided LASIK achieve excellent visual outcomes. Nonetheless, treatments based on a high-resolution aberrometer appear to offer superior results in some regards.

Hydrogel sealant to prevent recurrent epithelial ingrowth in the setting of a LASIK flap buttonhole

Purpose

To report the first case of hydrogel sealant to prevent the recurrence of epithelial ingrowth in a LASIK flap buttonhole.

Observations

A 67-year-old female presented ten years after undergoing bilateral LASIK with diffuse lamellar keratitis and flap dislodgement after blunt trauma to the right eye. She was found to have epithelial ingrowth with diffuse debris and striae, so her flap was lifted and the epithelial ingrowth was removed. However, a central buttonhole was noted intraoperatively. Once all the epithelium was removed, the flap was repositioned and hydrogel sealant (ReSure, Ocular Therapeutix, Bedford, MA) was used to fill the buttonhole as well as seal down the edges of the flap. Sixteen months postoperatively, the patient's uncorrected visual acuity was 20/50-2 and there was no recurrence of the epithelial ingrowth at the edges of the buttonhole.

Conclusions and importance

Preventing the recurrence of epithelial ingrowth is a challenging situation, especially in the setting of a LASIK flap buttonhole. The use of hydrogel sealant in the buttonhole and around the edges of the flap may offer an elegant and effective solution.

Prospective evaluation of a novel silicone corneal shield after PRK: 6-month efficacy, safety, and predictability outcomes

Purpose

The aim of this study was to report the 1-week and 6-month refractive outcomes of eyes treated with a novel silicone corneal shield designed to improve visual recovery after photorefractive keratectomy (PRK).

Patients and methods

This prospective, observational clinical trial recruited 45 myopic eyes with or without astigmatism at a university eye clinic to undergo wavefront-guided PRK followed by application of an investigational silicone corneal shield that was removed on postoperative day 4. The primary outcome measures were efficacy, predictability, and safety at the 6-month visit. The secondary end points included short-term uncorrected distance visual acuity (UDVA) and pain.

Results

No adverse outcomes occurred using the device. At 6 months, 79.5% of eyes achieved UDVA >20/20, 94.9% achieved ≥20/25, and 97.4% achieved ≥20/40. Also, 2.6% lost one line of corrected distance visual acuity and none lost two lines; 71.8% and 97.4% measured within ±0.25 and ±0.50 D of emmetropia, respectively. During the first week, preoperative UDVA improved from 1.34 logarithm of the minimum angle of resolution (logMAR; <20/400 Snellen) to 0.14 logMAR (>20/30) on postoperative day 1 (P<0.0001) and remained stable on days 2-3 (all P>0.05). After removal of the shield on day 4, UDVA declined by two lines before rebounding to 0.16 logMAR (>20/30) on day 7 (both P<0.001). Subjective metrics of pain all peaked between days 2 and 3 before declining.

Conclusion

The investigational silicone corneal shield is safe and effective when used after PRK and may aid early visual recovery and patient comfort, but comparative studies are needed to validate these preliminary findings.

Precis

One-week and 6-month refractive outcomes of a novel silicone corneal shield used after PRK show that the device is not only safe and effective but may also speed visual recovery.

Comparison of simulated keratometric changes following wavefront-guided and wavefront-optimized myopic laser-assisted in situ keratomileusis

Purpose

The aim of the study was to determine and compare the relationship between change in simulated keratometry (K) and degree of refractive correction in wavefront-guided (WFG) and wavefront-optimized (WFO) myopic laser-assisted in situ keratomileusis (LASIK).

Methods

A total of 51 patients were prospectively randomized to WFG LASIK in one eye and WFO LASIK in the contralateral eye at the Byers Eye Institute, Stanford University. Changes in simulated K and refractive error were determined at 1 year post-operatively. Linear regression was employed to calculate the slope of change in simulated K (ΔK) for change in refractive error (ΔSE). The mean ratio (ΔK/ΔSE) was also calculated.

Results

The ratio of ΔK to ΔSE was larger for WFG LASIK compared to WFO LASIK when comparing the slope (ΔK/ΔSE) as determined by linear regression (0.85 vs 0.83, p = 0.04). Upon comparing the mean ratio (ΔK/ΔSE), subgroup analysis revealed that ΔK/ΔSE was larger for WFG LASIK for refractive corrections of >3.00 D and >4.00 D (0.89 vs 0.83; p = 0.0323 and 0.88 vs 0.83; p = 0.0466, respectively). Both linear regression and direct comparison of the mean ratio (ΔK/ΔSE) for refractive corrections <4.00 D and >4.00 D revealed no difference in ΔK/ΔSE between smaller and larger refractive corrections.

Conclusion

WFO LASIK requires a smaller amount of corneal flattening compared to WFG LASIK for a given degree of refractive correction. For both, there was no significant difference in change in corneal curvature for a given degree of refractive error between smaller and larger corrections.

Quality of vision after wavefront-guided laser in situ keratomileusis or photorefractive keratectomy: Contralateral eye evaluation

PURPOSE

To compare quality of vision between laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

SETTING

Byers Eye Institute, Stanford University School of Medicine, Palo Alto, California, USA.

DESIGN

Prospective randomized case series.

METHODS

Patients had refractive surgery, with 1 eye treated with LASIK and the other with PRK. Eyes were randomized for dominance. The patients completed a questionnaire assessing quality of vision in each eye at the initial visit and 1, 3, 6, and 12 months postoperatively.

RESULTS

The study comprised 34 patients (68 eyes). There were no initial differences in quality of vision. The PRK eyes had worse clarity during the day (P = .001) and at night (P = .001), worse overall vision (P = .024), more vision fluctuation (P = .006), and more double vision (P = .022) at 1 month. Eyes with higher preoperative higher-order aberrations (HOAs) having PRK had worse clarity during the day and at night (P = .006 and P = .012, respectively) and more vision fluctuation (P = .041); PRK eyes with lower preoperative HOAs had worse daytime clarity (P = .036) at 1 month. After 1 month, there were no differences.

CONCLUSIONS

The quality of vision was better in LASIK eyes after 1 month. At subsequent visits, there was no significant difference in quality of vision.

Phototherapeutic keratectomy for epithelial basement membrane dystrophy

Purpose

The purpose of this study was to evaluate the long-term efficacy of phototherapeutic keratectomy (PTK) in treating epithelial basement membrane dystrophy (EBMD).

Methods

Preoperative and postoperative records were reviewed for 58 eyes of 51 patients with >3 months follow-up (range 3–170 months) treated for EBMD with PTK after failure of conservative medical treatment at Byers Eye Institute of Stanford University. Symptoms, clinical findings, and corrected distance visual acuity (CDVA) were assessed. The primary outcome measure was symptomatic recurrence as measured by erosions or visual complaints >3 months after successful PTK.

Results

For eyes with visual disturbances (n=30), preoperative CDVA waŝ20/32 (0.24 Log-MAR, SD 0.21) and postoperative CDVA was ~20/25 (0.07 LogMAR, SD 0.12; P<0.0001). Twenty-six eyes (86.7%) responded to treatment, with symptomatic recurrence in 6 eyes (23.1%) at an average of 37.7 months (SD 42.8). For eyes with painful erosions (n=29), preoperative CDVA was ~20/25 (0.12, SD 0.19) and postoperative CDVA was ~20/20 (0.05. SD 0.16; P=0.0785). Twenty-three eyes (79.3%) responded to treatment, with symptomatic recurrence in 3 eyes (13.0%) at an average of 9.7 months (SD 1.5). The probability of being recurrence free after a successful treatment for visual disturbances and erosions at 5 years postoperatively was estimated at 83.0% (95% confidence interval 68.7%–97.0%) and 88.0% (95% confidence interval 65.3%–96.6%), respectively.

Conclusion

The majority of visual disturbances and painful erosions associated with EBMD respond to PTK. For those with a treatment response, symptomatic relief is maintained over long-term follow-up.

Quality of Vision After Wavefront-Guided or Wavefront-Optimized LASIK: A Prospective Randomized Contralateral Eye Study

PURPOSE

To compare the effect of wavefront-guided and wavefront-optimized LASIK using different laser platforms on subjective quality of vision.

METHODS

The dominant eyes of 55 participants with myopia were randomized to receive either wavefront-guided LASIK treatment by the VISX Star S4 IR Custom-Vue excimer laser system (Abbott Medical Optics, Inc., Santa Clara, CA) or wavefront-optimized treatment by the WaveLight Allegretto Wave Eye-Q 400-Hz excimer laser system (Alcon Laboratories, Inc., Fort Worth, TX), whereas the fellow eye had the alternate laser treatment. Patients completed a questionnaire assessing quality of vision and visual symptoms (daytime and nighttime glare, daytime and nighttime clarity, halos, haze, fluctuating vision, and double vision) preoperatively and at postoperative months 1, 3, 6, and 12.

RESULTS

At 3, 6, and 12 months postoperatively, there was no significant difference in any individual symptom between the wavefront-guided and wavefront-optimized groups, although at 12 months wavefront-guided eyes trended toward having more excellent vision (wavefront-guided vs wavefront-optimized; 2.26 vs 2.43; P = .039). In the subgroup of patients with preoperative root mean square (RMS) higher order aberrations (HOAs) less than 0.3 µm in both eyes, the wavefront-optimized group demonstrated a trend toward worsened nighttime clarity (P = .009), daytime clarity (P = .015), and fluctuating vision (P = .046), and less excellent vision (P = .009) at 12 months.

CONCLUSIONS

Twelve months after surgery, most patients' self-reported visual symptoms were similar in eyes receiving wavefront-guided or wavefront-optimized LASIK. In general, 36% of patients preferred wavefront-guided LASIK, 19% preferred wavefront-optimized LASIK, and 45% had no preference at 12 months. The wavefront-guided preference was more pronounced in patients with lower baseline HOAs (RMS < 0.3 µm).

Comparison of self-reported quality of vision outcomes after myopic LASIK with two femtosecond lasers: a prospective, eye-to-eye study

Purpose

To compare self-reported quality of vision (QoV) outcomes after myopic LASIK (laser-assisted in situ keratomileusis) with two femtosecond lasers.

Design

Prospective, randomized, eye-to-eye study.

Methods

Consecutive myopic patients were treated with wavefront-guided LASIK bilaterally. Eyes were randomized according to ocular dominance. The flap of one eye was made with the IntraLase FS 60 kHz femtosecond laser with a conventional 70° side-cut, and the flap of the fellow eye was made with the IntraLase iFS 150 kHz femtosecond laser with an inverted 130° side-cut. Patients completed the validated, Rasch-tested, linear-scaled 30-item QoV questionnaire preoperatively and at Months 1, 3, 6, and 12.

Results

The study enrolled 120 fellow eyes in 60 patients. None of the measured QoV parameters exhibited statistically significant differences between the groups preoperatively or at any postoperative time point.

Conclusion

Creating LASIK flaps with an inverted side-cut using a 150 kHz femtosecond laser and with a conventional 70° side-cut using a 60 kHz femtosecond laser resulted in no significant differences in self-reported QoV assessed by the QoV questionnaire.

Comparison of ocular aberrations measured by a Fourier-based Hartmann-Shack and Zernike-based Tscherning aberrometer before and after laser in situ keratomileusis

PURPOSE

To assess agreement between a Hartmann-Shack aberrometer (Wavescan) and a Tscherning aberrometer (Wavelight Allegro Analyzer) and their respective agreement with manifest refraction before and after laser in situ keratomileusis (LASIK).

SETTING

Stanford Eye Laser Center, California, USA.

DESIGN

Prospective comparative observational study.

METHODS

Multiple readings were obtained both aberrometers preoperatively and 12 months after wavefront-guided LASIK. Sphere, cylinder, spherical equivalent (SE), defocus Z(2,0), astigmatism Z(2,2), spherical aberration Z(4,0), coma Z(3,1), trefoil Z(3,3), and total higher-order aberrations (HOAs) were compared using intraclass correlation coefficients (ICCs) (perfect agreement = 1; disagreement = 0).

RESULTS

In the 100 study eyes, preoperative agreement was good to excellent between the aberrometers for the parameters of defocus, astigmatism, and spherical aberration (ICC: 0.8, 0.9, and 0.7, respectively) but was poor for coma, trefoil, and total HOAs (ICC: 0.6, -0.2, and 0.4, respectively). At 12 months, ICCs worsened for all parameters (ICC: defocus = 0.6; astigmatism = 0.2; spherical aberration = 0.6; coma = 0.4; trefoil = -0.3; total HOAs = 0.4). Preoperative agreement of sphere, cylinder, and SE was good to excellent between the manifest refraction and both aberrometers (ICC Hartmann-Shack: 0.98, 0.95, and 0.97, respectively; ICC Tscherning: 0.97, 0.92, and 0.98, respectively). However, agreement was poor to fair between the manifest refraction and both aberrometers at 12 months (ICC Hartmann-Shack: 0.4, 0.1, and 0.4, respectively; ICC Tscherning: 0.03, 0.02, and 0.2, respectively).

CONCLUSIONS

Although some HOAs measured with both aberrometers agreed preoperatively, such agreement might not persist after LASIK. Spherocylinder measurements with both aberrometers seemed to agree closely with the manifest refraction before LASIK, but not at 12 months.

FINANCIAL DISCLOSURE

Dr. Manche has equity in Calhoun Vision, Inc., Krypton Vision, Seros Medical, LLC, and Veralas and is a consultant to Best Doctors, Gerson Lehrman Group.

Vector analysis of 1-year astigmatic outcomes from a prospective, randomized, fellow eye comparison of wavefront-guided and wavefront-optimized LASIK in myopes

PURPOSE

To compare the astigmatic outcomes of LASIK with a single excimer laser platform using either wavefront-guided (WFG) or wavefront-optimized (WFO) modes.

METHODS

Sixty-eight eyes of 34 patients underwent LASIK for myopia with the Wavelight Allegretto Eye-Q 400-Hz laser platform (Alcon Laboratories, Inc., Hüenberg, Switzerland). One eye underwent WFG-LASIK and the contralateral eye underwent WFO-LASIK. Alpins vector analysis of astigmatism was performed using manifest refraction measured preoperatively and 12 months postoperatively and vertexed to the corneal plane. Eyes were stratified for subgroup analysis based on preoperative manifest astigmatism.

RESULTS

WFG-LASIK and WFO-LASIK were similar with regard to surgically induced astigmatism, difference vector, magnitude of error, correction index, flattening index, and index of success. The angle of error was 80% less in the WFG group compared to the WFO group (1.92° ± 0.67º vs 9.66° ± 3.7º, P = .04).

CONCLUSIONS

WFG-LASIK and WFO-LASIK using the Alcon WaveLight Allegretto Eye-Q 400-Hz excimer laser platform produce similar astigmatic results in myopic patients; however, the WFG mode may produce slightly more predictable astigmatic corrections.

Contralateral eye-to-eye comparison of wavefront-guided and wavefront-optimized photorefractive keratectomy: a randomized clinical trial

IMPORTANCE

Wavefront-guided (WFG) and wavefront-optimized (WFO) platforms for refractive surgery are designed for improved visual outcomes. It is unclear which treatment profile is superior for patients undergoing photorefractive keratectomy (PRK).

OBJECTIVE

To compare the safety, efficacy, predictability, stability, and higher-order aberrations in eyes undergoing WFG and WFO PRK.

DESIGN, SETTING, AND PARTICIPANTS

A prospective, randomized, fellow-eye-controlled clinical trial was conducted at the Byers Eye Institute at Stanford with enrollment between April 2009 and March 2011; 1 year of follow-up was included. Of 90 patients screened, 71 patients (142 eyes) with less than 12.00 diopters (D) of spherical myopia and less than 3.00 D of astigmatism were enrolled consecutively.

INTERVENTIONS

One eye was randomized to undergo WFG PRK treatment (Visx CustomVue Star S4 IR excimer laser system; Abbott Medical Optics), and the fellow eye received WFO PRK treatment (WaveLight Allegretto Wave Eye-Q 400 Hz excimer laser system; Alcon Surgical).

MAIN OUTCOMES AND MEASURES

Data on the manifest refraction, uncorrected visual acuity, best-corrected visual acuity, 5% and 25% contrast best-corrected visual acuity, and higher-order aberrations were collected preoperatively and at the 1-, 3-, 6-, and 12-month follow-up visits.

RESULTS

Eyes undergoing both treatments had improved best-corrected visual acuity (WFG: mean, 0.05 [95% CI, 0.03-0.07]; WFO: mean, 0.04 [95% CI, 0.02-0.06]) and less sphere (WFG: mean, -4.79 [95% CI, -5.31 to -4.26]; WFO: mean, -4.61 [95% CI, -5.18 to -4.03]), cylinder (WFG: mean, 0.66 [95% CI, 0.49-0.82]; WFO: mean, 0.52 [95% CI, 0.35-0.69]), and spherical equivalents (WFG: mean, -4.45 [95% CI, -4.99 to -3.91]; WFO: mean, -4.34 [95% CI, -4.92 to -3.76]) (P < .001) but higher levels of spherical aberration (WFG: mean, -0.11 [95% CI, -0.15 to -0.06]; WFO: mean, -0.11 [95% CI, -0.14 to -0.07]) (P < .001) and higher-order root-mean-square aberrations (WFO: mean, -0.07 [95% CI, -0.12 to -0.02]; WFO: mean, -0.12 [95% CI, -0.17 to -0.70]) (P = .005 in WFG eyes and P < .001 in WFO eyes) at 12 months compared with preoperative measurements. A total of 93.0% of the eyes in the WFG group and 94.4% in the WFO had an uncorrected visual acuity of 20/20 or better at 12 months, with 56.3% in the WFG group and 43.7% in the WFO group gaining 1 or more lines of best-corrected visual acuity. The stability of the refractive correction was excellent for both groups.

CONCLUSIONS AND RELEVANCE

A difference in uncorrected visual acuity or contrast acuity between eyes undergoing WFG or WFO treatment at 3 months and beyond could not be identified. This lack of difference suggests that both systems can be used to provide excellent improvement in vision for persons with myopia.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01135719.

Day 1 wavefront aberrometry for prediction of refractive outcomes at year 1 in myopic LASIK

PURPOSE

To determine amount of change in wavefront aberrometric measurements from 1 day to 1 year after myopic LASIK.

METHODS

One hundred five eyes of 105 patients underwent wavefront-guided LASIK. Objective wavefront aberrometric refractions were recorded preoperatively, at postoperative day 1, and at postoperative year 1. Subjective manifest refractions were also collected at postoperative year 1.

RESULTS

When comparing objective wavefront aberrometric refractions at postoperative year 1 to postoperative day 1, there was a mean 0.33 diopter spherical equivalent myopic shift. There was no significant difference in the number of eyes within 1.00 diopter of emmetropia spherical equivalent measured by wavefront aberrometric refraction at postoperative day 1 or year 1. There was a correlation of R(2) = 0.14 between degree of preoperative myopia and myopic shift. Higher-order aberrations were overall not increased at day 1 but increased significantly by year 1. Objective aberrometric refractions at postoperative day 1 can be useful in prediction of long-term refractive outcomes.

CONCLUSIONS

There is a small myopic shift and an increase in higher-order aberrations when comparing wavefront aberrometry results at postoperative day 1 with those at postoperative 1 year.

A comparison of LASIK flap thickness and morphology between the Intralase 60- and 150-kHz femtosecond lasers

PURPOSE

To prospectively compare the achieved thickness and consistency of LASIK flaps created with a 60- and 150-kHz femtosecond laser.

METHODS

One hundred twenty eyes of 60 patients with myopia were treated with LASIK. One eye had flap created by the Intralase FS 60-kHz femtosecond laser (Abbott Medical Optics, Abbott Park, IL) and the fellow eye was treated with the IntraLase iFS 150-kHz femtosecond laser (Abbott Medical Optics). Eyes were randomized according to ocular dominance. Flap morphology and measurements were taken with anterior segment optical coherence tomography (AS-OCT) at the 1-month postoperative visit.

RESULTS

AS-OCT showed similar regular planar morphologies in both groups. The mean thickness of the flaps in the FS 60 group was significantly higher than that of the iFS 150 group (105.4 ± 3.9 μm vs 103.9 ± 4.8 μm, P = .009). The mean deviation from targeted flap thickness was not significantly different between the two groups.

CONCLUSIONS

The Intralase iFS 150-kHz femtosecond laser creates flaps of similar thickness and uniformity to the Intralase FS 60-kHz femtosecond laser.

One-year eye-to-eye comparison of wavefront-guided versus wavefront-optimized laser in situ keratomileusis in hyperopes

Background

To compare wavefront (WF)-guided and WF-optimized laser in situ keratomileusis (LASIK) in hyperopes with respect to the parameters of safety, efficacy, predictability, refractive error, uncorrected distance visual acuity, corrected distance visual acuity, contrast sensitivity, and higher order aberrations.

Methods

Twenty-two eyes of eleven participants with hyperopia with or without astigmatism were prospectively randomized to receive WF-guided LASIK with the VISX CustomVue S4 IR or WF-optimized LASIK with the WaveLight Allegretto Eye-Q 400 Hz. LASIK flaps were created using the 150-kHz IntraLase iFS. Evaluations included measurement of uncorrected distance visual acuity, corrected distance visual acuity, <5% and <25% contrast sensitivity, and WF aberrometry. Patients also completed a questionnaire detailing symptoms on a quantitative grading scale.

Results

There were no statistically significant differences between the groups for any of the variables studied after 12 months of follow-up (all P>0.05).

Conclusion

This comparative case series of 11 subjects with hyperopia showed that WF-guided and WF-optimized LASIK had similar clinical outcomes at 12 months.

Corneal sensation and dry eye symptoms after conventional versus inverted side-cut femtosecond LASIK: a prospective randomized study

PURPOSE

To compare corneal sensation and self-reported dry eye symptoms after femtosecond-assisted LASIK with conventional versus inverted side cuts.

DESIGN

Prospective, randomized, eye-to-eye study.

PARTICIPANTS

A total of 120 eyes in 60 participants with myopia.

METHODS

Fellow eyes were randomized to receive femtosecond-assisted LASIK with a conventional 70-degree side cut made with the 60 kHz IntraLase FS (Abbott Medical Optics, Santa Ana, CA) or an inverted 130-degree side cut made with the 150 kHz IntraLase iFS (Abbott Medical Optics). Cochet-Bonnet aesthesiometry (Luneau Ophthalmologia, Chartes, France) measured corneal sensation (60 mm = normal sensation; <60 mm = depressed sensation) preoperatively and at postoperative months 1, 3, 6, and 12. Participants also completed serial dry eye surveys using the same subscales (frequency, severity, bothersome) as the validated, Rasch-tested, linear-scaled Quality of Vision questionnaire.

MAIN OUTCOME MEASURES

Objective corneal sensation and self-reported light sensitivity, dryness, foreign body sensation, and pain/discomfort.

RESULTS

Preoperative corneal sensation as measured by mean Cochet-Bonnet aethesiometry was equal between the inverted and conventional side cut groups but was better in eyes with an inverted side cut compared with a conventional side cut at all postoperative months (inverted vs. conventional: 1 month, 14.5 vs. 13.2 mm; 3 months, 24.9 vs. 18.4 mm; 6 months, 51.2 vs. 42.6 mm; 12 months, 59.8 vs. 58.3 mm; all P ≤ 0.02). None of the subjective dry eye parameters demonstrated statistically significant differences between the groups at any time point.

CONCLUSIONS

The LASIK flaps with an inverted side cut are associated with superior recovery of corneal sensation compared with flaps with a conventional side cut during the first postoperative year; however, this may not translate to significant improvements in subjective dry eye symptoms.

Comparison of 2 wavefront-guided excimer lasers for myopic laser in situ keratomileusis: one-year results

PURPOSE

To compare laser in situ keratomileusis (LASIK) outcomes between 2 wavefront-guided excimer laser systems in the treatment of myopia.

SETTING

University eye clinic, Palo Alto, California, USA.

DESIGN

Prospective comparative case series.

METHODS

One eye of patients was treated with the Allegretto Wave Eye-Q system (small-spot scanning laser) and the fellow eye with the Visx Star Customvue S4 IR system (variable-spot scanning laser). Evaluations included measurement of uncorrected visual acuity, corrected visual acuity, and wavefront aberrometry.

RESULTS

One hundred eyes (50 patients) were treated. The mean preoperative spherical equivalent (SE) refraction was -3.89 diopters (D) ± 1.67 (SD) and -4.18 ± 1.73 D in the small-spot scanning laser group and variable-spot scanning laser group, respectively. There were no significant differences in preoperative higher-order aberrations (HOAs) between the groups. Twelve months postoperatively, all eyes in the small-spot scanning laser group and 92% in the variable-spot scanning laser group were within ±0.50 D of the intended correction (P = .04). At that time, the small-spot scanning laser group had significantly less spherical aberration (0.12 versus 0.15) (P = .04) and significantly less mean total higher-order root mean square (0.33 μm versus 0.40 μm) (P = .01). Subjectively, patients reported that the clarity of night and day vision was significantly better in the eye treated with the small-spot scanning laser.

CONCLUSIONS

The predictability and self-reported clarity of vision of wavefront-guided LASIK were better with the small-spot scanning laser. Eyes treated with the small-spot scanning laser had significantly fewer HOAs.

Wavefront-guided versus wavefront-optimized laser in situ keratomileusis for patients with myopia: a prospective randomized contralateral eye study

PURPOSE

To compare the clinical outcomes of wavefront-guided and wavefront-optimized laser in situ keratomileusis (LASIK).

DESIGN

Prospective, randomized, fellow-eye-controlled study.

METHODS

The setting was a single academic institution. The study population included 110 eyes of 55 patients with myopia with and without astigmatism. One eye of each patient was randomized to undergo wavefront-guided LASIK by the AMO Visx CustomVue S4 IR excimer laser system; the fellow eye received wavefront-optimized LASIK by the Alcon Allegretto Wave Eye-Q 400 Hz excimer laser system. Corneal flaps were constructed using the Intralase FS 60 Hz femtosecond laser. Patients were followed at postoperative months 1, 3, 6, and 12. The study's main outcome measures were uncorrected visual acuity, stability of refractive correction, contrast sensitivity, and wavefront aberrometry.

RESULTS

After 12 months, LASIK eyes had achieved visual acuity of 20/12.5 or better (30 eyes, 56%) in the wavefront-guided group compared to those receiving wavefront-optimized treatment (22 eyes, 41%) (P = 0.016). Average spherical equivalent refractions were -0.13 ± 0.46 diopters in wavefront-guided eyes whereas in wavefront-optimized eyes the refractions were -0.41 ± 0.38 diopters at 12 months. Wavefront-guided eyes also achieved better best-corrected visual acuity at both the 5% and 25% contrast levels (P = 0.022 and P = 0.004, respectively). There were no differences in levels of residual astigmatism (P = 0.798) or in higher order aberrations (P = 0.869).

CONCLUSIONS

Both wavefront-guided and wavefront-optimized treatments are able to correct myopia safely and effectively in eyes with and without astigmatism. However, wavefront-guided treatment platforms appear to offer significant advantages in terms of residual refractive error, uncorrected distance acuity and contrast sensitivity.

Prospective randomized contralateral eye evaluation of subjective quality of vision after wavefront-guided or wavefront- optimized photorefractive keratectomy

PURPOSE

To compare the effect of wavefront-guided (WFG) and wavefront-optimized (WFO) photorefractive keratectomy (PRK) on patient perceived quality of vision.

METHODS

Seventy-one patients (142 eyes) were enrolled in this prospective, randomized, fellow eye controlled study. One eye was randomized to undergo WFG PRK treatment by the AMO Visx CustomVue S4 IR excimer laser system (Abbott Medical Optics, Inc., Santa Clara, CA) and the fellow eye received WFO PRK treatment by the Alcon Allegretto Wave Eye-Q 400 Hz excimer laser system (Alcon Laboratories, Inc., Fort Worth, TX). Patients answered questionnaires on their visual symptoms and quality of vision preoperatively and at 1, 3, 6, and 12 months after surgery.

RESULTS

Patients in both groups reported better vision compared to baseline from 3 months onward (mean change in score of 1.56 to 2.51 in the WFO group and 1.54 to 2.28 in the WFG group, P ⩽ .003). Both groups experienced less nighttime glare from 6 months onward (P ⩽ .030). Halos, double vision, and visual clarity were initially worse (P ⩽ .025) but not significantly different after 1 month. Haze and fluctuating vision resolved after 3 months. Visual symptoms were similar between the two groups at all times (P ⩾ .059) except at 6 months, when patients felt their WFG eyes had more excellent vision (P = .029). A composite of all symptoms was also similar between the groups until 12 months when patients had fewer symptoms in their WFO eye (P = .044).

CONCLUSIONS

One year after surgery, patient self-reported visual symptoms were not significantly different in eyes receiving WFG or WFO PRK. However, the average of all symptoms was lower in eyes receiving wavefront-optimized treatment.

Pupil size and LASIK: a review

PURPOSE

To provide a literature review on the evidence both for and against pupil size as an independent predictor of adverse visual outcomes after LASIK.

METHODS

Peer-reviewed publications on the effect of pupil size on LASIK outcomes since 2002 are reviewed. Particular attention was paid to the following attributes of each publication: type of study, number of patients or eyes, mean age, mean level of myopia, mean pupil size, testing conditions, ablation zone diameter, presence or absence of blend zones, and mean follow-up period.

RESULTS

Among the 19 studies examined, none correlates a persistent relationship between pupil size and night vision complaints (NVCs) beyond 3 months when LASIK was performed with a 6.0-mm optical zone or larger ablation. The studies that did explicitly determine a correlation either included some or all patients with ablation zones smaller than 6.0 mm or did not specify ablation diameter at all. Among the studies that had drawn more mixed conclusions, the studies either covered short follow-up intervals (1 to 3 months) or showed a progressive improvement in NVCs over time in a relatively small patient cohort.

CONCLUSIONS

As keratorefractive technology continues to evolve, the role of pupil size warrants further investigation; however, based on the literature reviewed herein, modern LASIK has negated the role of the low light pupil in predicting adverse visual outcomes after LASIK outside of the early postoperative period.

One-year outcomes from a prospective, randomized, eye-to-eye comparison of wavefront-guided and wavefront-optimized LASIK in myopes

OBJECTIVE

To compare wavefront (WF)-guided and WF-optimized LASIK in myopes.

DESIGN

Prospective, randomized, eye-to-eye study.

PARTICIPANTS

A total of 72 eyes of 36 participants with myopia with or without astigmatism.

METHODS

Participants were randomized to receive WF-guided or WF-optimized LASIK with the WaveLight Allegretto Eye-Q 400-Hz excimer laser platform (Alcon, Inc., Hüenberg, Switzerland). LASIK flaps were created using the 150-kHz IntraLase iFS (Abbott Medical Optics, Santa Ana, CA). Evaluations included measurement of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), <5% and <25% contrast sensitivity, and WF aberrometry. Patients also completed a validated questionnaire detailing symptoms on a quantitative scale.

MAIN OUTCOME MEASURES

Safety, efficacy, predictability, refractive error, UDVA, CDVA, contrast sensitivity, and higher-order aberrations (HOAs).

RESULTS

The frequency with which the WF-guided and WF-optimized groups achieved postoperative UDVA of ≥ 20/16 or ≥ 20/20 and the frequency with which the groups lost 1 or 2 or more lines or maintained their preoperative CDVA were not statistically different from each other (all P > 0.05). The frequency with which the WF-guided group attained a refractive error within ± 0.25 diopters of emmetropia was higher than in the WF-optimized group (67.6%, 95% confidence interval [CI], 50.4-84.8 vs. 41.2%, 95% CI, 23.2-59.2; P = 0.03). The WF-guided group's mean UDVA was better than the WF-optimized group's UDVA by approximately 1 Early Treatment Diabetic Retinopathy Study line (-0.17 ± 0.11 logarithm of the minimum angle of resolution [logMAR], slightly <20/12 Snellen vs. -0.13 ± 0.12, slightly >20/16; P = 0.05). There were no statistically significant differences in contrast sensitivity, astigmatism, coma, or higher-order root mean square error between the groups (all P > 0.05), but the WF-guided group had less trefoil compared with the WF-optimized group (0.14 ± 0.07 vs. 0.20 ± 0.09; P < 0.01). There were no statistically significant differences in subjective parameters between the groups (all P > 0.05).

CONCLUSIONS

Wavefront-guided and WF-optimized LASIK using the Alcon WaveLight Allegretto Eye-Q 400-Hz excimer laser platform provide similar results in myopic patients; however, the WF-guided approach may yield small gains in visual acuity, predictability, and HOAs.

Wavefront-guided laser in situ keratomileusis (Lasik) versus wavefront-guided photorefractive keratectomy (Prk): a prospective randomized eye-to-eye comparison (an American Ophthalmological Society thesis)

PURPOSE

To compare the safety and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) vs photorefractive keratectomy (PRK) in a prospective randomized clinical trial.

METHODS

A cohort of 68 eyes of 34 patients with -0.75 to -8.13 diopters (D) of myopia (spherical equivalent) were randomized to receive either wavefront-guided PRK or LASIK in the fellow eye using the VISX CustomVue laser. Patients were evaluated at 1 day, 1 week, and months 1, 3, 6, and 12.

RESULTS

At 1 month, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), 5% and 25% contrast sensitivity, induction of higher-order aberrations (HOAs), and subjective symptoms of vision clarity, vision fluctuation, ghosting, and overall self-assessment of vision were worse (P<0.05) in the PRK group. By 3 months, these differences had resolved (P>0.05). At 1 year, mean spherical equivalent was reduced 94% to -0.27 ± 0.31 D in the LASIK group and reduced 96% to -0.17 ± 0.41 D in the PRK group. At 1 year, 91% of eyes were within ±0.50 D and 97 % were within ±1.0 D in the PRK group. At 1 year, 88% of eyes were within ±0.50 D and 97% were within ±1.0 D in the LASIK group. At 1 year, 97% of eyes in the PRK group and 94% of eyes in the LASIK group achieved an UCVA of 20/20 or better (P=0.72). Refractive stability was achieved in both PRK and LASIK groups after 1 month. There were no intraoperative or postoperative flap complications in the LASIK group. There were no instances of corneal haze in the PRK group.

CONCLUSIONS

Wavefront-guided LASIK and PRK are safe and effective at reducing myopia. At 1 month postoperatively, LASIK demonstrates an advantage over PRK in UCVA, BSCVA, low-contrast acuity, induction of total HOAs, and several subjective symptoms. At postoperative month 3, these differences between PRK and LASIK results had resolved.

Comparison of intraoperative subtraction pachymetry and postoperative anterior segment optical coherence tomography of laser in situ keratomileusis flaps

PURPOSE

To prospectively compare intraoperative subtraction pachymetry flap thickness measurements and postoperative anterior segment optical coherence tomography (AS-OCT) flap thickness measurements in eyes that had laser in situ keratomileusis (LASIK) flap creation with a femtosecond laser or a mechanical microkeratome.

SETTING

Stanford Eye Laser Center, Stanford University School of Medicine, Stanford, California, USA.

DESIGN

Comparative case series.

METHODS

Each patient received wavefront-guided LASIK using an Intralase femtosecond laser in 1 eye and a Hansatome mechanical microkeratome in the fellow eye. Flap morphology was assessed with an ultrasound pachymeter intraoperatively and an AS-OCT system postoperatively at 1 year.

RESULTS

Thirty-six eyes (18 patients) were enrolled. Intraoperative subtraction pachymetry consistently underestimated mechanical microkeratome flap thickness compared with postoperative AS-OCT (P<.001). There was no significant difference between intraoperative subtraction pachymetry and postoperative AS-OCT measurements for femtosecond flaps (P=.38). The overall mean variation in flap thickness (ie, mean deviation from targeted flap thickness) was 2.6 μm (range 3 to 11 μm) with the femtosecond laser and 14.2 μm (range 17 to 52 μm) with the mechanical microkeratome (P<.001). Postoperative AS-OCT measurements showed femtosecond flaps had a planar configuration and mechanical microkeratome flaps had a meniscus-shaped configuration.

CONCLUSIONS

The femtosecond laser created more uniformly planar flaps than the mechanical microkeratome as measured by intraoperative subtraction pachymetry and postoperative AS-OCT. Postoperative AS-OCT measurements varied less than intraoperative subtraction pachymetry measurements for mechanical microkeratome flaps.

FINANCIAL DISCLOSURE

Neither author has a financial or proprietary interest in any material or method mentioned.

Dry eye after laser in situ keratomileusis with femtosecond laser and mechanical keratome

PURPOSE

To prospectively compare dry-eye symptoms after laser in situ keratomileusis (LASIK) with mechanical keratome-created flaps and femtosecond laser keratome-created flaps.

SETTING

Department of Ophthalmology, Stanford University School of Medicine, Stanford, California, USA.

DESIGN

Randomized clinical trial.

METHODS

Fellow eyes were prospectively randomized to the mechanical keratome group and femtosecond laser keratome group. Patients had wavefront-guided LASIK using a mechanical keratome in 1 eye and a femtosecond laser keratome in the fellow eye. They completed dry-eye questionnaires preoperatively and 1, 3, 6, and 12 months postoperatively. The effect of laser ablation depth, sex, age, and flap thickness on dry-eye symptoms was also analyzed.

RESULTS

The study enrolled 51 patients. There was no statistically significant change in dry-eye symptoms except in the femtosecond group 1 month postoperatively (mean increase 1.08) (P=.03). There were no significant differences in symptoms between the 2 groups (P=.7). The dry-eye score was 1.3 points lower in women than in men (P=.01). Central ablation depth, flap thickness, and age did not significantly affect the reported dryness.

CONCLUSION

There appeared to be no statistically significant difference in self-reported dry-eye symptoms between the mechanical keratome group and the femtosecond laser keratome group.

Late onset secondary cataract following implantation of an iris-fixated phakic intraocular lens

PURPOSE

To report a case of bilateral late onset anterior cortical cataract following implantation of an iris-fixated phakic intraocular lens (pIOL).

METHODS

Single observational case report.

RESULTS

Three and a half years following uncomplicated consecutive implantation of iris-fixated pIOL in both eyes, anterior cortical cataract changes inferiorly emanating from the site of enclavation of the lens in the right eye were noted. By 7 years after implantation, anterior cortical cataract changes were seen emanating from the enclavation sites superiorly and inferiorly in both eyes. These cataracts did not cause any loss of corrected distance visual acuity.

CONCLUSIONS

This case demonstrates that a potential complication of an iris-fixated pIOL is late onset secondary cataract formation.