First Clinical Experience With the Alcon LADAR 6000 Excimer Laser

PURPOSE

To evaluate the reliability and ergonomics and to assess the first clinical results provided by the new LADAR 6000 excimer laser used to correct myopia and astigmatism, both by conventional and wavefront-guided ablation.

METHODS

Seventy-four consecutive eyes from 37 patients underwent LASIK as the first field evaluation protocol of the Alcon LADAR 6000 excimer laser. Forty-six eyes were treated by wavefront-guided ablation to correct a manifest spheroequivalent refractive error (MSRE) of -0.50 to -9.75 diopters (D) (mean: -4.19 D, cylinder range: 0.0 to -3.50 D). Twenty-eight eyes were treated by conventional ablation to correct MSRE of -1.00 to -7.00 D (mean: -3.11 D, cylinder range: 0.0 to -1.75 D). Uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), MSRE, and wavefront measurements were assessed. Follow-up was 3 months for all eyes.

RESULTS

Three months after surgery, all eyes were within +/- 1.00 D of intended correction. Forty-three (93.5%) eyes treated with wavefront-guided ablation and 25 (89.3%) eyes treated with conventional ablation were within +/- 0.50 D. All eyes reached > or = 20/25 UCVA. UCVA > or = 20/20 was reached in 45 (97.8%) wavefront-guided eyes and 26 (92.9%) conventional eyes; 37 (80.4%) wavefront-guided eyes and 17 (60.7%) conventional eyes had 20/16 UCVA. None of the eyes treated lost > or = 2 lines of BSCVA.

CONCLUSIONS

The LADAR 6000 excimer laser results proved to be at least as accurate, predictable, and safe as the results currently achieved with the LADARVision4000 excimer laser. The improved microscope illumination enhances visibility for better consistency and ease of use. The better ergonomics and software design of this platform improved patient flow.

Photorefractive Keratectomy for Hyperopia Using an Erodible Disc and Axicon Lens: 2-Year Results

BACKGROUND

This paper presents the results over a 2-year follow-up of the first human trial of photorefractive keratectomy (PRK) for correction of hyperopia using an erodible disc excimer laser delivery system (Summit) coupled to an axicon lens.

METHODS

We treated 25 eyes of 21 patients for a mean correction of +3.38 +/- 0.97 D (range, +1.00 to +4.00 D). The hyperopic correction was made using an erodible disc inserted on the laser optical pathway; an axicon lens was then used to create a blend transition zone. Eyes were evaluated at 1, 3, 6, and 12 months after surgery. For a smaller series of 11 eyes, we also present 24-month results.

RESULTS

Mean refractive error 1 month after treatment (25 eyes) was -2.35 +/- 1.55 D (range, +1.00 to -6.50 D). Eight eyes (32%) had a spectacle-corrected visual acuity loss greater than 1 line. Twelve months after treatment, mean spherical equivalent refraction was -0.47 +/- 0.80 D (range, +1.25 to -2.25 D). Nineteen eyes showed an improvement (range, 3 to 8 lines) in uncorrected distance visual acuity and 23 showed improvement in uncorrected vision at reading distance (1 to 7 lines).

CONCLUSION

This technique proved effective in reducing hyperopia, but predictability must be demonstrated in a larger treatment group. Safety was confirmed by the absence of delayed reepithelialization and the absence of spectacle-corrected visual acuity loss greater than 1 line at 1 year after surgery.

Ultrastructural and Immunohistochemical Findings after Linear Excimer Laser Keratectomy

BACKGROUND

One human pathology specimen has been studied previously following the use of the excimer laser for the correction of astigmatism. We report histopathologic findings following linear corneal excisions with the excimer laser.

METHODS

A 193 nm excimer laser was used to create symmetrical, transverse excisions in a human eye to correct astigmatism. Three months later, a full-thickness corneal transplant was performed due to unsatisfactory refractive results. The excised corneal button was examined with light microscopy, transmission electron microscopy and immunohistochemistry.

RESULTS

An area 10 to 20-micron wide was observed between the epithelial cells within the keratectomy and the sharply dissected stromal lamellae. This area stained positive for laminin and pro-collagen type III. Some epithelial cells showed processes reaching into this area. Descemet's membrane, immediately underneath the area of the keratectomy, contained atypically striated collagen fibers.

CONCLUSIONS

These findings demonstrate wound healing changes similar to those reported following diamond knife keratotomy and photorefractive keratectomy for myopia. The changes in the posterior cornea are similar to those previously reported when an excimer laser beam approached Descemet's membrane.

Photorefractive Keratectomy for Compound Myopic Astigmatism With an Eye Cup Erodible Mask Delivery System

BACKGROUND

The erodible mask is a new energy delivery system for the 193-nm argon fluoride excimer laser. It consists of a polymethyl-methacrylate button, whose profile is transferred by photoablation onto the corneal surface. We present the 6- and 12-month results of this technique in the correction of compound myopic astigmatism.

METHODS

We performed the mask procedure on 21 eyes of 16 subjects (mean age, 30.7 years; range, 24 to 46) to correct combined myopia and astigmatism. Attempted myopic correction ranged between -1.50 diopters (D) and -10.00 D (mean, -7.07 D). Attempted astigmatic correction ranged between -1.50 D and -4.00 D (mean, -2.46 D).

RESULTS

Mean procedure error was: sphere +0.74 D (range, -3.00/+5.00), cylinder -1.41 D (range, -3.50/0.00) at 1 month after surgery; sphere +0.18 D (range, -2.50/+ 3.50), cylinder -1.56 D (range, -4.00/0.00) at 6 months; and sphere -1.30 D (range, -3.00/0.00), cylinder was -1.25 D (range, -2.00/-0.50) at 12 months (10 eyes). During follow up, haze values were never higher than 1, except for one case of haze 2 that regressed to 0 during follow up. Postoperative uncorrected visual acuity improved in all eyes where emmetropia was envisaged; none of the eyes lost spectacle-corrected visual acuity lines 6 or 12 months after surgery.

CONCLUSIONS

The erodible mask proved effective and fairly predictable mainly in the correction of the spherical component of refractive error, while the correction of astigmatism revealed greater unpredictability, with a constant trend to undercorrection.