Initial results of photorefractive keratectomy and laser in situ keratomileusis performed by a single surgeon

Learning curve of laser-assisted subepithelial keratectomy

PURPOSE

To study the effect of the learning curve of laser-assisted subepithelial keratectomy (LASEK) on the visual and refractive results.

METHODS

This retrospective study comprised 56 eyes that had LASEK for myopia. The eyes were among the first 143 that had LASEK by the same surgeon with the same excimer laser and same nomogram. The 56 eyes were separated into 2 groups. Group 1 included the first 28 eyes to have LASEK by the surgeon. Group 2 comprised the last 28 eyes in the series whose refractive error could be matched with that in Group 1. The outcomes in the 2 groups were compared.

RESULTS

The mean preoperative spherical refraction was -3.90 diopters (D) +/- 1.90 (SD) in Group 1 and -3.70 +/- 2.53 D in Group 2 (P = .2). There were no significant differences in preoperative cylinder or best spectacle-corrected visual acuity (BSCVA) between groups. The postoperative uncorrected visual acuity (UCVA) was significantly worse in Group 1 on 1 day and 7 days postoperatively (P = .02 and P = .03, respectively); there was no significant difference at 1 month and 3 months. The safety index (postoperative BSCVA/preoperative BSCVA) and efficacy index (postoperative UCVA/preoperative BSCVA) were better in Group 2, although the difference was not statistically significant. The spherical refraction 3 months postoperatively was +0.50 +/- 0.83 D in Group 1 and +0.10 +/- 0.27 D in Group 2 (P = .02); 75.00% of eyes and 96.42% of eyes, respectively, were within +/-0.50 D of the intended correction (P = .01). Seven percent of eyes in Group 1 and no eye in Group 2 lost 2 or more lines of BSCVA.

CONCLUSIONS

Results indicate that the outcomes of LASEK depend on surgeon experience. Thus, caution is advised when interpreting LASEK results without knowing the surgeon's level of experience.

Complications and visual outcome of LASIK performed by anterior segment fellows vs experienced faculty supervisors

PURPOSE

To determine the complication rates and visual outcome of laser-assisted in situ keratomileusis (LASIK) that is performed by anterior segment fellows and to compare their results with the results of their experienced faculty supervisors.

DESIGN

A single-center, retrospective, interventional, nonrandomized, comparative case series.

METHODS

Chart review of the initial 50 LASIK procedures that were performed by each of 10 anterior segment fellows and the first 50 inclusion criteria-matched, contemporaneously performed cases of four faculty members at the King Khaled Eye Specialist Hospital between March and December 2003.

RESULTS

There were no statistically significant differences between fellow and faculty cases with respect to complication rates and final visual outcomes. The fellows were significantly more likely to experience microkeratome-related flap complications during their first 25 cases, compared with their second 25 cases (4.8% vs 1.2%; P = .03). Fellows were significantly more likely to perform enhancements (8.0% vs 2.0%; P = .0002), after which the eyes in their group were more likely to be within 1 diopter of the intended refractive target than those in the faculty group (96.0% vs 91.0%; P = .01). Although not statistically significant, eyes in the fellow group were four-fold (2.0% vs 0.5%) more likely to lose two or more lines of best spectacle corrected visual acuity than those in the faculty group.

CONCLUSION

To minimize the adverse impact of complications during the learning curve of novice LASIK surgeons, the introduction of this procedure in a well-structured, supervised setting (such as a subspecialty fellowship training program) is recommended.

Laser in situ keratomileusis for refractive error after cataract surgery

PURPOSE

To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) to correct refractive error following cataract surgery.

SETTING

The Eye Institute, Sydney, Australia.

METHODS

This retrospective study reviewed 23 eyes (19 patients; 10 female, 9 male) treated with LASIK for refractive error following cataract surgery. The Summit Apex Plus and Ladarvision excimer laser and the SKBM microkeratome were used. The mean age was 63.5 years (range 50 to 88 years). The mean length of follow-up was 8.4 months (range 1 to 12 months) and mean interval between cataract surgery and LASIK was 12 months (range 2.5 to 46 months).

RESULTS

The mean preoperative spherical equivalent refraction (SEQ) for myopic eyes was -3.08 +/- 0.84 diopters (D) (range -4.75 to -2.00 D) and for hyperopic eyes was +1.82 +/- 1.03 D (range +0.75 to +3.00 D). The mean improvement following LASIK surgery was greater for myopic than hyperopic eyes (myopic, 2.54 +/- 1.03 D versus hyperopic, 1.73 +/- 0.62 D; P=.033). The percentage of patients within +/-0.5 D of intended refraction post-LASIK surgery was 83.3% for myopic eyes and 90.9% for hyperopic eyes and all eyes were within +/-1.0 D of intended (P<.001). The percentage of eyes with uncorrected visual acuity of 20/40 or better in the myopic group improved from none preoperatively to 91.7% postoperatively (P<.001) and in the hyperopic group improved from 27.3% preoperatively to 90.9% postoperatively (P=.008). No eyes lost 2 or more lines of best corrected visual acuity.

CONCLUSION

Laser in situ keratomileusis appears to be effective in correcting refractive error following cataract surgery. Longer-term studies are required to determine refractive stability.

Outcomes of Laser in situ Keratomileusis in a Refractive Surgery Fellowship Program

PURPOSE

The purpose of this study was to document the learning curve and evaluate the success of laser in situ keratomileusis (LASIK) performed by fellows in a Cornea/External Disease and Refractive fellowship program.

METHODS

Two surgeons performed LASIK within a fellowship training program between July 2000 and August 2001. A retrospective review was conducted to determine the visual outcomes and operative complications from this non-comparative case series of 755 consecutive eyes. All LASIK procedures were performed using a Bausch & Lomb Technolas 217A laser and the Bausch & Lomb Hansatome or the Automated Corneal Shaper microkeratome. All eyes were evaluated for operative complications. Visual acuity was reported with a minimum of 1 month follow-up.

RESULTS

Data analysis revealed that uncorrected visual acuity of 20/40 or better was attained in 99.4% of treated eyes, and 20/20 or better in 77.2%. With both eyes open, 100% of patients saw 20/30 or better, 94% saw 20/20 or better, 70% saw 20/15 or better, and 5.5% saw 20/10. Flap related complications occurred in 7 of 755 eyes (0.9%) and all were successfully treated. Forty-two eyes (5.6%) were lost to follow-up prior to the 1-month examination and were excluded from analysis of visual acuity.

CONCLUSIONS

Favorable operative and visual acuity 1-month results in 755 eyes after LASIK with the Bausch & Lomb Technolas 217A laser were in part due to a well organized system of education, patient examination, execution of surgery, and postoperative care. A team approach was essential.

Evaluation of corneal functional optical zone after laser in situ keratomileusis

PURPOSE

To evaluate the corneal functional optical zone (FOZ) after laser in situ keratomileusis (LASIK) using a primary 6.0 mm ablation diameter without a transition zone.

SETTING

University-based practice.

METHODS

In this retrospective study, 76 eyes of 53 patients who had LASIK for myopia were evaluated. The size of the preoperative and postoperative FOZ was compared in each eye. Preoperative refraction, attempted correction, and achieved correction were correlated with the preoperative and postoperative FOZ using regression analysis.

RESULTS

After LASIK, the FOZ decreased a mean 1.2 mm +/- 0.67 (SD) (P < 0.0001). The size of the FOZ was correlated with the preoperative manifest refraction, attempted correction, and achieved correction (P <.0001). The FOZ reduction was significantly correlated with the preoperative manifest refraction, attempted correction, and achieved correction (P <.05). Before LASIK, there was no correlation between the FOZ and the preoperative manifest refraction (P = 0.9427).

CONCLUSIONS

Spherical aberrations exist within the laser ablation zone and are related to the amount of myopic treatment. This has implications for patients with large pupil diameters under mesopic conditions. Future studies are necessary to understand the implications in patients with high refractive errors.

Comparison of photorefractive keratectomy, astigmatic PRK, laser in situ keratomileusis, and astigmatic LASIK in the treatment of myopia

PURPOSE

To determine factors affecting refractive and visual outcomes in patients treated with astigmatic and spherical photorefractive keratectomy (A-PRK and PRK) and laser in situ keratomileusis (A-LASIK and LASIK).

SETTING

University referral refractive surgery clinic.

METHODS

Refractive and visual acuity results in 619 eyes of 388 consecutive patients having refractive surgery over a 2-year period by a single surgeon were retrospectively analyzed. Patients were divided into mild-to-moderate myopia (spherical equivalent [SE] less than -6.12 diopters [D]) and high myopia (SE -6.12 D or higher). Multivariate and logistic regression analyses were performed.

RESULTS

Refractive results in flap-based and PRK-based procedures were comparable in mild-to-moderate myopia patients but were significantly better in high-myopia patients having flap-based procedures. Refractive stability was greater in flap-based procedures than in PRK-based procedures. Elliptical ablations yielded a marked reduction in the astigmatic cylinder in patients having A-LASIK and A-PRK, while spherical PRK induced small amounts of with-the-rule astigmatism. Complications were uncommon in both groups, consisting primarily of epithelial ingrowth in flap-based procedures and haze in PRK-based procedures. Multivariate regression identified the preoperative SE as a significant determinant of PRK outcomes (with higher success for lower myopia) and intraocular pressure as a minor determinant of outcomes in PRK-based and flap-based procedures. Logistic regression suggested that only the preoperative SE was a significant factor in predicting the likelihood of poor outcomes in PRK patients.

CONCLUSIONS

Refractive outcomes were almost identical in patients having elliptical or spherical ablations with flap-based or PRK-based procedures. In eyes with mild-to-moderate myopia, there was little difference in refractive or visual outcomes between flap-based and PRK-based procedures; in eyes with high myopia, flap-based procedures offered more predictable refractive outcomes and better visual outcomes.

Risk Factors for Insufficient Fixation of Microkeratome During Laser in situ Keratomileusis

PURPOSE

To investigate the potential risk factors leading to insufficient fixation of a microkeratome during laser in situ keratomileusis (LASIK), especially in Asian eyes.

METHODS

We performed a retrospective analysis of 1809 eyes of 972 patients that underwent LASIK. Profiles of patients (age, sex, past medical history, width of palpebral fissure, corneal power, and postoperative clinical course) whose operations were discontinued due to insufficient fixation were compared to all LASIK patients.

RESULTS

Insufficient fixation was observed in 18 eyes of 16 patients. Those patients were significantly younger (26.1 +/- 5.5 yr) compared to all patients (32.3 +/- 8.6 yr). Mean keratometric power was 42.40 +/- 1.37 D in patients with insufficient fixation and 43.60 +/- 1.40 D in all patients (P < .001). Maximum width of palpebral fissure with eyes wide open was 0.96 +/- 0.20 mm in patients with insufficient fixation, and 1.10 +/- 0.19 mm in all patients (P = .0015). These patients subsequently underwent LASIK utilizing combinations of cooling, frequent corticosteroid instillation for several hours, and lateral canthotomy.

CONCLUSION

Narrow palpebral fissures commonly found in Asian populations might be a risk factor for insufficient fixation of a microkeratome in LASIK, especially in young patients with flat corneas.

200 Hz flying-spot technology of the LaserSight LSX excimer laser in the treatment of myopic astigmatism: six and 12 month outcomes of laser in situ keratomileusis and photorefractive keratectomy

PURPOSE

To evaluate safety, efficacy, predictability, and stability in the treatment of myopic astigmatism with laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) using the 200 Hz flying-spot technology of the LaserSight LSX excimer laser.

SETTING

SynsLaser Clinic, Tromsø, Norway.

METHODS

This retrospective study included 110 eyes treated with LASIK and 87 eyes treated with PRK that were available for evaluation at 6 and 12 months, respectively. The mean preoperative spherical equivalent (SE) was -5.35 diopters (D) +/- 2.50 (SD) (range -1.13 to -11.88 D) in the LASIK eyes and -4.72 +/- 2.82 D (range -1.00 to -15.50 D) in the PRK eyes. The treated cylinder was 4.00 D in both groups. Eleven (8.5%) LASIK eyes and 8 (7.4%) PRK eyes had secondary surgical procedures before 6 and 12 months, respectively, and were excluded when the 6 and 12 month outcomes were analyzed.

RESULTS

None of the eyes lost 2 or more lines of best spectacle-corrected visual acuity. Seventy-seven percent of the LASIK eyes and 78% of the PRK eyes achieved an uncorrected visual acuity of 20/20 or better; 98% in both groups achieved 20/40 or better. The SE was within +/-0.5 D of the desired refraction in 83% of the LASIK eyes and 77% of the PRK eyes; it was within +/-1.0 D in 97% and 98%, respectively. The cylinder correction had a mean magnitude of error of 0.04 +/- 0.31 D (range -0.96 to +0.85 D) in the LASIK eyes and 0.02 +/- 0.37 D (range -1.44 to +0.72 D) in the PRK eyes. Refractive stability was achieved at 1 month and beyond in the LASIK eyes and at 3 months and beyond in the PRK eyes.

CONCLUSION

The outcomes of this study are comparable to those achieved with lasers that use small-beam technology with a lower frequency, as well as with other types of delivery systems. They suggest that the 200 Hz technology used in the LaserSight LSX excimer laser is safe, effective, and predictable and that with LASIK and PRK the results are stable when treating low to moderate myopia and astigmatism up to 4.0 D.