Keratophakia and keratomileusis: safety and effectiveness. American Academy of Ophthalmology

Inlays and the cornea

Presbyopia is a growing problem in view of an aging global population and increasingly patients desire spectacle-free solutions to address this condition. Surgically implanted corneal inlays have been the topic of renewed research efforts in the past several years as a treatment option for presbyopia, with several approaches being used to modify the refractive properties of the cornea and enhance near vision. In this review we discuss historical approaches to corneal inlay surgery, critically appraise the current generation of presbyopia-correcting corneal inlays and their associated complications and consider the future prospects for emerging corneal inlay technologies that aim address the shortcomings of currently available inlays.

Corneal indentation in the early management of acute angle closure

PURPOSE

To describe in detail corneal indentation (CI) in the management of a series of patients treated for acute angle closure (AAC).

DESIGN

Retrospective, consecutive, noncomparative case series.

PARTICIPANTS

Seven consecutive patients (8 eyes) referred to the authors with the diagnosis of AAC. Patients presented to the Prince of Wales Hospital, Randwick, or to the private practices of the authors.

INTERVENTION

Seven patients (8 eyes) underwent CI as part of their early management for AAC.

MAIN OUTCOME MEASURES

Reduction in intraocular pressure (IOP), symptoms of AAC and pain relief.

RESULTS

Of the 7 patients, complete data were available for 6. The IOP was significantly reduced (P<0.05) and 3 of 4 patients with severe acute pain reported early resolution of pain after CI. The average reduction in IOP was 20.9 mmHg (range +1 to -45). All patients subsequently underwent definitive management with laser peripheral iridotomies or lensectomy using phacoemulsification. Three patients treated acutely with CI without any medical agents had a mean IOP reduction of 21 mmHg (range, 20-23) after indentation.

CONCLUSIONS

Corneal indentation is a rapid, portable, and effective method of reducing elevated IOP in the setting of AAC. It can be performed with instrumentation that is readily at hand and allows for rapid pain relief. This reduction in IOP improves corneal clarity and permits further definitive management of the patient with AAC.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Surgical Correction of Hyperopia

Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.

Excimer laser photorefractive keratectomy for hyperopia: 7.5-year follow-up

PURPOSE

To report the results of a long-term prospective study to evaluate refractive stability and safety of hyperopic photorefractive keratectomy (H-PRK).

SETTING

Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

METHODS

Twenty-one patients (49%) (40 eyes) of cohort of 43 patients who participated in 1 of the first clinical trials of H-PRK were assessed at a mean follow-up of 90.7 months (range 62 to 106 months). The H-PRK was performed using a Summit Technology Apex Plus Excimer laser (Summit Technology, Inc.). The mean preoperative spherical equivalent refraction (SEQ) was +4.70 diopters (D) (range +2.00 to +7.50 D). Patients were allocated to 1 of 4 treatment groups based on their preoperative refraction and received 1 of the following spherical corrections: +1.50 D, +3.00 D, +4.50 D, or +6.00 D.

RESULTS

At 7.5 years, the refractive correction remained stable with a mean difference in SEQ between 1 year and 7.5 years of +0.28 D. The mean manifest SEQ was +0.83 D (range +5.00 to -3.00 D). Sixty-seven percent of eyes having corrections of +1.50 D and +3.00 D were within +/-1.00 D of the predicted correction. Predictability was poorer with +4.50 D and +6.00 D corrections, with 40% of eyes within +/-1.00 D of that expected. An improvement in uncorrected near acuity was achieved in 35 eyes (87.5%), and 35 eyes (87.5%) showed an improvement in uncorrected distance acuity from preoperative levels. Best spectacle-corrected visual acuity (BSCVA) was unchanged or improved from preoperative values in 25 eyes (62.5%). Three eyes (8%) lost 2 lines of Snellen BSCVA, which in 2 cases was attributable to cataract formation. A peripheral ring of haze, 6.5 mm in diameter, appeared in most eyes. Its intensity was greatest at 6 months and then diminished with time. In 10 eyes (25%), remnants of the haze ring were evident at 7.5 years and subepithelial iron rings, 6.5 mm in diameter were evident in 26 eyes (70%). No patient complained of night-vision problems and no eye developed ectasia.

CONCLUSIONS

In H-PRK, refractive stability achieved at 1 year was maintained up to 7.5 years with no evidence of hyperopic shift, diurnal fluctuation, or late regression. Peripheral corneal haze decreased with time but was still evident in a number of eyes at the last follow-up visit.

5-year follow-up of LASIK for hyperopia

PURPOSE

To assess the long-term efficacy and stability of LASIK for hyperopia (+0.75 to +7.00 diopters [D]).

DESIGN

Retrospective follow-up study of a previous phase III multicenter clinical trial (unpublished data).

PARTICIPANTS

Patients who had been treated for hyperopia (33 individuals, 47 eyes) attended follow-up 5 years after surgery. The preoperative mean spherical equivalent at the spectacle plane was +3.58 D (range, +0.75 to 7.00 D), and the attempted mean spherical correction at the corneal plane was +3.18 D (range, +1.00 to +6.00 D).

INTERVENTION

Treatments were performed using a Moria LSK One microkeratome and a Summit Technology SVS Apex Plus excimer laser fitted with an Axicon.

MAIN OUTCOME MEASURES

Manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity, corneal transparency, complications, and patient satisfaction were recorded.

RESULTS

At 5 years, for treatments between +1.00 to +3.00 D, 71.0% of eyes were within +/-1.00 D of the intended correction, and for treatments between +3.5 to +6.0 D, 37.5% of eyes were within +/-1.00 D of intended correction. From 12 to 54 months after surgery for all patients, there was a hyperopic shift of +0.53 D (range, -0.13 to +3.13 D), with 51.1% of eyes experiencing an increase of +0.50 D or more and 27.7% of eyes showing a hyperopic shift of more than +1.00 D. This hyperopic shift was +0.67 D (range, 0 to +1.125 D) for patients younger than 40 years of age and +0.44 D (range, -1.33 to +1.50 D) for patients between 43 and 55 years of age.

CONCLUSIONS

LASIK was moderately effective for the correction of low degrees of hyperopia. However, there was regression throughout the 5-year follow-up that was greater than would be expected as a result of aging. Long-term stability of hyperopic LASIK refractive corrections, therefore, is uncertain.

Laser Intrastromal Keratoplasty-Case Report

PURPOSE

To evaluate the feasibility of correcting high hyperopia by means of intrastromal implantation of a laser shaped corneal lenticule prepared from a human donor eye.

METHODS

A female patient with high hyperopia and irregular astigmatism resulting from multiple laser in situ keratomileusis procedures and lamellar keratoplasty underwent laser intrastromal keratoplasty. Her preoperative uncorrected visual acuity (UCVA) was 20/300 and best spectacle-corrected visual acuity (BSCVA) was 20/100 with a refraction of +8.00 -1.00 x 130 degrees. Corneal topography showed a highly irregular corneal surface. Central corneal thickness was 398 microm. Lenticule preparation included mechanical de-epithelialization of a human donor eye, keratectomy with a microkeratome, user-designed software combining a photorefractive keratectomy (PRK) treatment for +8.00 D sphere, an ablation zone of 7.0 mm, and a circumferential cut (internal diameter of 6.5 mm) for tissue ablation. Implantation involved re-lifting the flap, positioning the lenticule onto the corneal bed, and repositioning of the flap.

RESULTS

The operation was uneventful as was the early postoperative follow-up. BSCVA improved to 20/50 with +1.00 -2.25 x 120 degrees at 2 months postoperatively. Corneal topography showed a more regular cornea with increased curvature in all meridians. Central corneal thickness increased to 600 microm.

CONCLUSION

Laser intrastroma keratoplasty may be an option for correcting high hyperopa and irregular astigmatism in eyes with a thin corneal bed.

Long-term evaluation of hyperopic laser in situ keratomileusis

PURPOSE

To evaluate the efficacy, safety, and predictability of hyperopic laser in situ keratomileusis (H-LASIK).

SETTING

Departments of Ophthalmology, Hadassah University Hospital, Jerusalem, and Assaf Harofeh Medical Center, Zerifin, Israel.

METHODS

This prospective noncomparative case series studied the results of H-LASIK in the first 92 consecutive eyes of 50 patients with up to +10.25 diopters (D) of hyperopia. For analysis, the patients were divided into 3 groups based on preoperative hyperopia: low hyperopia (< +3.00 D), moderate hyperopia (> or = +3.00 to 6.00 D), and high hyperopia (> or = +6.00 D).

RESULTS

Forty-two patients, 77 eyes (83.7%), were followed for at least 12 months. At 12 months, the mean manifest spherical equivalent was +0.33 +/- 0.65 D (93.1% of eyes within +/-1.0 D of the intended correction) in the low myopia group, +0.21 +/- 0.60 D (92.3% within +/-1.0 D of the intended correction) in the moderate hyperopia group, and +1.62 +/- 1.50 D (36.4% within +/-1.0 D of the intended correction) in the high hyperopia group. The uncorrected visual acuity (UCVA) was 20/40 or better in all eyes (100%), 24 eyes (92.3%), and 13 eyes (59.1%) in the low, moderate, and high hyperopia groups, respectively. Comparing the UCVA at the last examination with the best corrected visual acuity (BCVA) before surgery in all patients showed that 59 eyes (76.6%) were within +/-1 line and 18 eyes (23.4%) were within +/-2 or more lines of the preoperative BCVA. Three eyes (3.9%) in the high hyperopia group lost 2 or more lines of BCVA. Three eyes (3.9%) had flap- related complications. Eight patients (15 eyes) with a follow-up less than 12 months did not have intraoperative or postoperative complications.

CONCLUSION

Laser in situ keratomileusis was a safe, effective, and predictable procedure for hyperopia up to +6.0 D and less predictable for higher hyperopia.

Laser in situ Keratomileusis Results of DOS and Windows Software Versions for the Nidek EC-5000 Excimer Laser Using the Same Nomogram

PURPOSE

To compare the results of laser in situ keratomileusis (LASIK) correction for myopia and myopic astigmatism between the previous DOS software version and the Windows software version for the Nidek EC-5000 excimer laser, using the same nomogram.

METHODS

This retrospective review included 2021 eyes (980 patients) after LASIK using the Nidek EC-5000 excimer laser. Of these, 1,632 eyes were corrected with the DOS software version and the other 389 eyes were corrected with the Windows software version of the laser. Both groups were treated with the same surgical nomogram. Minimum follow-up time was 6 months. Patients were classified into range of myopia: low, moderate, and high.

RESULTS

Postoperative uncorrected visual acuity was not statistically significantly different between the two groups in any range of refractive error. There was no loss of best spectacle-corrected visual acuity for any patient. Uncorrected visual acuity equal to or better than 20/40 was achieved in 96.3% of eyes in the Windows version group and 94.9% in the DOS version.

CONCLUSION

Results for the correction of myopia or myopic astigmatism were similar using the Nidek EC-5000 excimer laser with either the DOS software version or Windows software version, with the same surgical nomogram.

Early Rhegmatogenous Retinal Detachment Following Laser in situ Keratomileusis for High Myopia

PURPOSE

Four eyes had early rhegmatogenous retinal detachment within 3 months of laser in situ keratomileusis (LASIK) for correction of high myopia using the microkeratome, Clear Corneal Molder.

METHODS

In two eyes, retinal detachment resulted from horseshoe tears, one occurring in an otherwise normal region of the retina and the other at the margin of an area of lattice degeneration detected during preoperative examination. The first eye was treated with retinopexy using a 287 encircling scleral exoplant, drainage of subretinal fluid, and laser photocoagulation by indirect ophthalmoscopy. The other eye was treated with pneumatic retinopexy and cryotherapy. In the other eyes, retinal detachment was the result of giant tears with no evidence of prior retinal degeneration. These eyes were treated with pars plana vitrectomy, fluid-gas exchange with 15% perfluoropropane (C3F8), endolaser photocoagulation, and a 42 encircling scleral exoplant.

RESULTS

After treatment, the first two eyes achieved spectacle-corrected visual acuity of 20/40. In the last two eyes, final spectacle-corrected visual acuity was 20/400 in one eye and light perception in the other.

CONCLUSIONS

Although no cause-effect relationship between LASIK and retinal detachment can be stated, these cases suggest that LASIK may be associated with retinal detachment, particularly in highly myopic eyes. Further studies are necessary to determine high-risk patient characteristics.

Surgical correction of severe myopia with an angle-supported phakic intraocular lens

PURPOSE

To evaluate the effectiveness, predictability, and safety of a fourth-generation angle-supported anterior chamber phakic intraocular lens (IOL) in patients with severe myopia.

SETTING

Refractive Surgery and Cornea Unit, Alicante Institute of Ophthalmology, Miguel Hernández University School of Medicine, Alicante, Spain.

METHODS

In this prospective study, 23 eyes (16 patients) with a mean preoperative myopia of -19.56 diopters (D) +/- 1.76 (SD) (range -16.75 to -23.25 D) were implanted with the ZSAL-4 phakic IOL. Basic examinations were performed before and after surgery in all patients. Eighteen eyes were also studied by clinical specular microscopy, and the endothelium was analyzed for cell density, coefficient of variation in cell size, and hexagonality. The location of the IOL in the anterior chamber was evaluated in 10 eyes by A-scan biometry. To evaluate haptic geometry, a theoretical mechanical model was used. The follow-up was 24 months in all patients.

RESULTS

Uncorrected visual acuity was 20/40 or better in 13 eyes (56.0%) 12 months after surgery and in 14 eyes (60.8%) at 24 months. Best spectacle-corrected visual acuity improved 0.19 at 12 and 24 months (0.1 = 1 line) from preoperative values. The efficacy index was 1.12 at 24 months and the safety index, 1.45. The mean postoperative spherical equivalent was -0.65 +/- 0.65 D at 24 months. The postoperative spherical equivalent was within +/-1.00 D of emmetropia in 19 eyes (82.6%) at 12 and 24 months. The mean endothelial cell loss was 3.50% at 12 months and 4.18% at 24 months. The coefficient of variation in cell size decreased from 0.34 before surgery to 0.28 at 24 months after surgery. The IOL was located 0.79 +/- 0.24 mm in front of the crystalline lens. Postoperative complications included night halos in 6 eyes (26.1%) at 12 and 24 months and pupil ovalization in 4 eyes (17.4%). Intraocular lens rotation was observed in 10 eyes (43.5%) at 24 months. Two eyes (8. 7%) developed a slight inflammatory response during the first 6 months. Our mechanical model predicted that the compression forces against the angle structures were greater at the first footplate than at the second.

CONCLUSIONS

Implantation of the ZSAL-4 IOL in the anterior chamber of phakic eyes was effective and predictable in correcting severe myopia. However, the ZSAL-4 did not prevent pupil ovalization, IOL rotation, or low-grade postoperative uveitis. Improvements in haptic design following our mechanical model could decrease these haptic-related complications.

Hyperopic laser in situ keratomileusis with the Nidek EC-5000 excimer laser

OBJECTIVE

To evaluate the efficacy, safety, and predictability of hyperopic laser in situ keratomileusis (H-LASIK) using modified software.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

The first 72 consecutive eyes of 44 patients with up to +5.00 diopters (D) hyperopia.

INTERVENTION

Hyperopic LASIK using the Automatic Corneal Shaper (ACS; Chiron Vision, Claremont, CA) and the Nidek EC-5000 excimer laser (Nidek, Tokyo, Japan).

MAIN OUTCOME MEASURES

Uncorrected visual acuity, manifest spherical equivalent (MSE), best-corrected visual acuity (BCVA), and complications were studied.

RESULTS

At 6 months, in the low hyperopia group (<3.00 D), mean MSE was +0.30 +/- 0.71 D, with 88.9% eyes within 1 D of emmetropia compared with +1.09 +/- 0.92 D and 51.8% within 1 D of emmetropia in the moderate hyperopia group (> or =3.00 D; P = 0.003). Uncorrected visual acuity was 20/40 or better in 43 of 45 eyes (95.6%) and in 21 of 27 (77.8%) eyes in the low and moderate hyperopia groups, respectively. Only one eye (1.4%) from the moderate hyperopia group lost two lines of BCVA. Eighteen eyes (25%) required retreatment to correct residual hyperopia, 9 eyes (20.0%) in the low hyperopia group and 9 eyes (33.3%) in the moderate hyperopia group. Retreatments resulted in an MSE of +0.02 +/- 0.45 D and +0.04 +/- 0.73 D in the low and moderate hyperopia groups, respectively. No flap-related complications were seen.

CONCLUSIONS

Hyperopic LASIK with the ACS and the Nidek EC-5000 excimer laser using our modified software is a safe, effective, and predictable procedure for low hyperopia. Results are satisfactory up to moderate hyperopia. Significant regression can occur for low and moderate hyperopia. Retreatment can be performed safely and effectively to improve the visual and refractive results.

Hyperopic photorefractive keratectomy with the erodible mask and axicon system: two year follow-up

PURPOSE

To evaluate efficacy and long-term stability of hyperopic photorefractive keratectomy (H-PRK) using the erodible mask and Axicon system.

SETTING

Department of Ophthalmology, St. Thomas' Hospital, London, England.

METHODS

Forty-three patients (43 eyes), with a mean preoperative refraction (spherical equivalent) of +4.54 diopters (D) (range +1.75 to +7.50 D), were treated using an Apex Plus(R) excimer laser (Summit Technology). This uses an erodible mask to ablate a 6. 50 mm diameter hyperopic correction and an Axicon to fashion a 1.50 mm blend zone around the correction. The overall ablation diameter was 9.50 mm. Follow-up was 2 years.

RESULTS

At 2 years, the mean manifest refraction was +0.16 D (range +4.125 to -4.000 D), with the induced correction appearing stable after 9 months. Based on the Munnerlyn algorithm, predictability was acceptable for corrections up to +4.50 D, with 68% of eyes within +/-1.00 D of the predicted correction. It was poorer for +6.00 D corrections, with 33% of eyes within +/-1.00 D of that expected. Patient satisfaction was high. Forty eyes (93%) had an improvement in uncorrected near visual acuity and 37 (86%), an improvement in uncorrected distance acuity. A peripheral ring of haze, 6.5 mm in diameter, appeared in all eyes 1 month postoperatively. Its intensity was maximal at 3 to 9 months and then diminished over time. There were no significant differences in measurements of the central corneal transparency at 12 and 24 months and those preoperatively. Measurements of flicker contrast sensitivity, forward light scatter (glare), and scotopic halos showed no significant differences between preoperative values and those measured after 6 months.

CONCLUSIONS

Achieved H-PRK corrections with the erodible mask and Axicon system agreed closely with the Munnerlyn algorithm, with refractive stability after 9 months. Predictability was acceptable for corrections up to +4.50 D. Axial corneal transparency was not compromised and visual performance, in terms of best spectacle-corrected visual acuity, forward light scatter, and night halos, was not impaired.

High incidence of cataract formation after implantation of a silicone posterior chamber lens in phakic, highly myopic eyes

OBJECTIVE

To assess the effectiveness and safety of implantation of a negative, silicone, posterior chamber intraocular lens (IOL) in the ciliary sulcus of phakic, highly myopic eyes.

DESIGN

Noncomparative consecutive interventional series.

PARTICIPANTS

Eighteen eyes of 10 patients suffering from high-degree myopia (spherical equivalent < -10 diopters) undergoing implantation of a Fyodorov 094M-1 IOL by the same surgeon (P.H.B.) were evaluated.

INTERVENTION

A standard surgical technique was used in all patients under peribulbar anesthesia. The IOL was implanted in the ciliary sulcus immediately in front of the natural lens under protection of a viscoelastic substance (Healon) through a 3.5-mm temporal or nasal clear-corneal tunnel. No sutures were necessary in any case. A peripheral iridectomy was performed intraoperatively in 14 eyes, whereas 4 additional eyes received a yttrium-aluminum-garnet peripheral iridectomy after surgery. At the end of surgery, gentamicin and dexamethasone were given both topically and subconjunctivally.

MAIN OUTCOME MEASURES

Visual acuity and refraction were measured before surgery, as well as 1 day, 3 months, 6 months, and 2 years after surgery. Postoperative complications were recorded.

RESULTS

Best-corrected visual acuity remained unchanged (1 eye) or improved (6 eyes by 1, 5 eyes by 2, and 2 eyes by 3 Snellen lines, respectively) in 14 of 17 eyes, whereas 3 eyes experienced a decrease in best-corrected visual acuity by 1 Snellen line. Postoperative refraction approached the desired slight undercorrection at all times of examination. Cataract formation of the anterior subcapsular (8 eyes) or nuclear (only 1 eye) type was observed in overall 9 (52.9%) of 17 eyes. When considering only the patients with a follow-up of 2 years, the incidence of cataract formation was 81.9% (9 of 11 eyes).

CONCLUSIONS

The high incidence of cataract formation should discourage the implantation of the type of IOL used in this study in phakic eyes to correct high-degree myopia.

Corneal flap thickness in laser in situ keratomileusis using an SCMD manual microkeratome

PURPOSE

To evaluate corneal flap thickness in laser in situ keratomileusis (LASIK) and to measure variables correlated with corneal flap thickness.

SETTING

Kangnam St. Mary's Hospital, Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea.

METHODS

This prospective study comprised 69 eyes of 66 patients having LASIK with the VISX Star laser and SCMD manual microkeratome. Corneal thickness, keratometry, and refractive error were measured preoperatively, the time taken to complete the corneal flap and its thickness were recorded intraoperatively, and visual outcome was followed postoperatively. Corneal flap thickness was calculated as the thickness of the corneal stromal bed subtracted from the total corneal thickness.

RESULTS

Mean corneal flap thickness was 137.18 microns +/- 33.66 (SD). The thickness in 32 eyes (46.4%) was less than 135 microns, in 17 eyes (24.6%) from 135 to 165 microns, and in 20 eyes (29.0%) greater than 165 microns. There was no relationship between corneal flap thickness and degree of myopia, steepening of cornea, or time taken to complete the flap. However, the thickness of the corneal flap increased with the thickness of the cornea. Visual outcome was slightly better in the group with thick corneal flaps than in the one with thin corneal flaps, although the difference was not statistically significant.

CONCLUSION

Corneal flap thickness was variable in LASIK using the SCMD microkeratome. There was a correlation between corneal flap thickness and preoperative corneal thickness.

The status of hyperopic laser-assisted in situ keratomileusis

The development of excimer laser technology, coupled with advances in lamellar corneal surgery, has heralded a new era in the treatment of refractive errors. This paper discusses the current status of hyperopic laser-assisted in situ keratomileusis. This surgical modality is at a relatively early stage of investigation but appears to offer promise for the surgical correction of hyperopia. This paper considers the evolution of the technique, analyzes the current literature, and discusses the current indications, limitations, and possible future developments.

Excimer laser assisted in situ keratomileusis for hyperopia

PURPOSE

To evaluate hyperopic surgical correction with 6.0 mm optical zone hyperopic laser in situ keratomileusis (LASIK) after various refractive procedures.

SETTING

Buzard Eye Institute, Las Vegas, Nevada, USA.

METHODS

This study followed 14 eyes of 14 patients who had hyperopic LASIK with a VISX Star laser. Mean follow-up was 8 months. The patients represented a variety of preoperative situations, including primary radial keratotomy (RK) (5 eyes) primary automated lamellar keratectomy (ALK) (2 eyes), primary LASIK (3 eyes), congenital hyperopia (1 eye), and combinations of ALK, RK, and LASIK. In all patients, a toroidal or "doughnut-shaped" ablation was constructed with the use of a 3.5 mm diameter soft contact lens as a blocking agent centrally with a 6.0 mm outside beam diameter.

RESULTS

Mean preoperative spherical equivalent was +1.33 diopters (D) +/- 0.5 (SD) (range +0.50 to +1.88 D). The mean spherical equivalent was -0.32 +/- 1.20 D (range -1.25 to +2.63 D) at 1 month postoperatively and -0.15 +/- 0.60 D (range -1.13 to +1.25 D) at the last follow-up. Uncorrected visual acuity of 20/40 was obtained by 13 eyes (93%). No eye lost 2 or more lines of best corrected visual acuity at last follow-up. Four eyes required a postoperative LASIK enhancement procedure to correct induced myopia. No significant complications were seen.

CONCLUSION

Hyperopic LASIK with the technique used in this study appeared safe, predictable, and stable. It represents a simple way to add hyperopic correction to existing laser systems.

Retreatment after laser in situ keratomileusis

OBJECTIVE

To evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) retreatment for correcting residual myopia.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS AND INTERVENTION

Fifty-nine consecutive eyes (43 patients) underwent LASIK retreatment at 3 or 6 months after the primary LASIK procedure. Lifting the corneal flap and reablating the stromal bed with a VISX 20/20 excimer laser was the procedure used for LASIK enhancement.

MAIN OUTCOME MEASURES

The following parameters were studied before and after retreatment: visual acuity, refraction, videokeratography, applanation tonometry, and corneal thickness. Complications after LASIK enhancement also were evaluated. Follow-up was 12 months.

RESULTS

Before retreatment, only 3.38% of eyes (2 of 59) had an uncorrected visual acuity of 0.5 (20/40) or better, and after retreatment, this percentage increased to 60% (30 of 50) at 6 months and 61.8% (34 of 55) at 12 months. After reoperation, mean best-corrected visual acuity improved by half a line over the values before retreatment. The preretreatment refraction of -2.92 +/- 1.22 diopters (D) (mean +/- standard deviation) decreased significantly to -0.44 +/- 0.80 D at 6 months and to -0.61 +/- 0.82 D at 12 months (P < 0.001). In 82% of eyes (41 of 50) at 6 months and 81.8% (45 of 55) at 12 months, the spherical equivalent was within 1.00 D of emmetropia. There was a significant regression of effect (0.38 D) between 3 and 12 months (P < 0.01). Postretreatment refraction was related to the original refraction before the primary LASIK, the preretreatment refraction, and the ablation diameter used. Although no vision-threatening complications were found, epithelial ingrowth and flap melting were more common after than before LASIK retreatment, with 31% of eyes at 12 months with epithelial ingrowth and 10.9% with flap melting. However, LASIK enhancement improved decentration and night-vision problems.

CONCLUSIONS

LASIK retreatment was an effective and predictable procedure for correcting residual myopia. Epithelial ingrowth and flap melting were more frequent after than before LASIK retreatment, whereas decentration and night-vision symptoms improved.

Excimer laser photorefractive keratectomy for the correction of hyperopia using an erodible mask and axicon system

PURPOSE

The purpose of the study is to evaluate photorefractive keratectomy for the correction of hyperopia using the erodible mask and Axicon system.

METHODS

Forty-three patients (43 eyes) with a mean refraction (spherical equivalent) of +4.54 diopter (D) (range, +1.75 to +7.50 D) were treated using a Summit Technology "Apex Plus" excimer laser. This system uses an erodible mask to create a 6.50-mm diameter hyperopic correction over the axial cornea. An Axicon then is used to fashion a 1.50-mm "blend zone" around the correction. On the basis of preoperative refractions, patients were assigned to 3 groups: 2 groups of 14 patients underwent either "+2.00 D" or "+3.00 D" corrections and 15 patients had "+4.00 D" corrections.

RESULTS

All patients had a reduction in their hyperopia with an overcorrection, especially in the first month after surgery and some stability in the refractive change at 3 to 6 months. The mean manifest refraction (n = 43) at 6 months was -0.17 D (range, +4.50 D to -3.125 D). Patient satisfaction was high. At 6 months, all eyes had an improvement in unaided near visual acuity. Unaided distance acuity was improved in 37 eyes (86%). A ring of haze 6.5 mm in diameter appeared in all eyes 1 month after surgery. Night halo measurements at 6 months showed no differences from preoperative levels. Flicker contrast sensitivity and forward light scatter (glare) measurements showed no differences after surgery.

CONCLUSIONS

In this short-term study, photorefractive keratectomy for hyperopia using the erodible mask and Axicon system appeared to be a promising procedure. Visual performance, in terms of flicker contrast sensitivity, forward light scatter, and night halos, was not compromised. There was an overcorrection based on the manufacturer's algorithms. Manipulation of the treatment algorithms should improve future predictability.

Laser in situ keratomileusis to correct high myopia

PURPOSE

To evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) in 143 eyes with myopia from 8.00 to 20.00 diopters (D).

SETTING

Alicante Institute of Ophthalmology, University of Alicante School of Medicine, Alicante, Spain.

METHODS

This prospective study comprised 143 eyes (94 patients) that had LASIK with the Chiron Automated Corneal Shaper and the VISX 20/20 excimer laser using a multizone profile and a sutureless hinged corneal flap technique.

RESULTS

Uncorrected visual acuity of 20/40 or better in 45.0% of eyes 3 months postoperatively and in 46.4% at 6 months. Best corrected visual acuity (BCVA) improved by 0.07 at 3 and 6 months and was stable after 3 months. Mean spherical equivalent was -13.19 diopters (D) +/- 2.89 (SD) preoperatively and +0.51 +/- 1.63 D at 3 months and +0.18 +/- 1.66 D at 6 months postoperatively. At 3 months, spherical equivalent was within 1.00 D of emmetropia in 57.5% of all eyes, 71.0% of eyes with a baseline refraction from -8.00 to -11.99 D (n = 59), 44.4% with a baseline refraction from -12.00 to -15.99 D (n = 54), and 53.0% of eyes with a baseline refraction from -16.00 to -20.00 D (n = 30). The respective 6 month percentages were 60.0, 72.4, 46.0, and 50.0%. The regression of effect was similar in all groups (approximately 0.50 D) between 1 and 3 months, although the high myopia group had further regression. Significant corneal steepening and an increase in corneal thickness occurred between 1 and 3 months. Flap thickness was always less than predicted with both the 130 microns plates, and achieved laser ablation was deeper than programmed. The relationships between postoperative refraction and preoperative keratometry and postoperative refraction and the difference in achieved versus programmed ablation were significant. Complications at 6 months included epithelial ingrowth, corneal flap melting, decentered ablation, and irregular astigmatism with loss of BCVA, although none was vision threatening.

CONCLUSION

In this study, LASIK was effective and predictable in the correction of high myopia but was more accurate for myopia up to 12.00 D. Current surgical algorithms must be modified to improve predictability in higher corrections. Longer follow-up is necessary to evaluate long-term incidence of vision-threatening complications.

Laser in situ keratomileusis to treat myopia: early experience

PURPOSE

To present our early experience in methodology and results of laser in situ keratomileusis (LASIK) in treating moderate and high myopia.

SETTING

Vardinoyannion Eye Institute of Crete and the Cornea and Refractive Surgery Service, Department of Ophthalmology, Heraklion University Hospital, Crete, Greece.

METHODS

Forty-three moderately to highly myopic eyes has LASIK. Follow-up was between 12 and 24 months. The Draeger's rotor microkeratome was used to create a 150 microns thick 8.5 x 9.5 mm corneal flap, and the stromal bed was ablated for the myopic correction using the Munnerlynn photorefractive keratectomy algorithm. The preoperative spherical equivalent ranged from -8.50 to -25.87 diopters (D). Attempted correction ranged from 8.00 to 16.00 D. Four eyes developed complications (i.e., anterior chamber perforation and keratoconus, intrastromal epithelial cells, macular lacquer cracks, and transient endothelial decompensation) and were excluded from the study. The remaining 39 eyes were retrospectively divided into two groups--A (21 eyes) and B (18 eyes)--according to the preoperative spherical equivalent (higher or lower than -14.00 D, respectively).

RESULTS

Refraction and corneal topography stabilized between 4 and 12 weeks postoperatively. Best spectacle-corrected visual acuity was within one Snellen line in all eyes. At 24 months, 19 eyes (79.2%) were within 2.00 D of intended correction. Attempted correction (12.20 D +/- 2.30 [SD]) was very close to mean achieved correction at 12 and 24 months (11.60 +/- 2.65 D). Mean postoperative astigmatism at 24 months (1.41 +/- 0.87 D; range 0 to 3.50 D) was close to the mean preoperative value (1.52 +/- 1.08 D; range 0 to 4.00 D). An average 2.43% endothelial cell loss was observed at 24 months.

CONCLUSION

With limitations, LASIK could be considered as a treatment for moderate and high myopia.

Lamellar Keratoplasty for Hyperopia

PURPOSE

Lamellar keratoplasty for hyperopia (automated lamellar keratoplasty for hyperopia) can correct hyperopia by weakening the cornea with a deep lamellar resection. The safety and efficacy of the procedure is uncertain.

METHODS

Twenty-four eyes of 17 patients underwent hyperopic lamellar keratoplasty using the automated corneal shaper (Chiron Corp, Irvine, Calif) by one surgeon using a flap technique. The mean attempted correction was +3.90 +/- 0.90 D (range, +2.00 to +6.00). The eyes were followed for 1 month (23 eyes) to 6 months (17 eyes).

RESULTS

Six months after hyperopic lamellar keratoplasty, the mean difference between attempted and achieved correction was an undercorrection of +1.40 +/- 0.80 diopters (D) with 7 of 17 eyes within 1.00 D of the attempted correction. No eyes were overcorrected, and 15 eyes were undercorrected. In eyes with a refractive goal of emmetropia, uncorrected visual acuity was 20/40 or better in 13 of 15 eyes and 20/20 or better in 8 of 15 eyes. No eye lost two or more lines of spectacle-corrected visual acuity at 3 or 6 months postoperatively. Between 1 and 6 months, there was a mean hyperopic shift of 0.20 D. There was clinically significant epithelial ingrowth into the interface in two eyes.

CONCLUSION

Hyperopic lamellar keratoplasty is an effective method of reducing hyperopia and induces little irregular astigmatism. The nomogram we used produces a consistent undercorrection. Refraction appears to stabilize at 1 month, but longer follow up is necessary to assess stability.

Initial results of automated lamellar keratoplasty for correction of myopia: one year follow-up

PURPOSE

To report our initial results with automated lamellar keratoplasty (ALK) to correct myopia and to evaluate the short-term efficacy, safety, and predictability of this procedure.

METHODS

A prospective series of 128 eyes of 81 consecutive patients who had ALK were reviewed for a mean follow-up of 13.6 months (range 12 to 19 months). Preoperative data, intraoperative parameters, and postoperative visual acuity, refraction, keratometric readings, and complications at 1 day, 1 week, 1, 3, and 6 months, 1 year, and last follow-up visit were used for analysis. The procedure was performed for myopia in 120 eyes (-4.50 to -13.25 diopters [D]) and for residual myopia following radial keratotomy (RK) in eight eyes (-1.75 D to -3.75 D). A hinged-flap technique was used in 17 cases (13%) once this method was introduced.

RESULTS

Preoperative mean uncorrected visual acuity was 0.04 +/- 0.05 (20/500). Postoperatively (12 to 19 months), overall uncorrected visual acuity was 20/40 or better in 86.4% of eyes with a mean uncorrected acuity of 0.68 +/- 0.22 (20/30) 76.2% of eyes were within 1.00 D of emmetropia and 93.6%, within 2.00 D. After the initial ALK procedure, 77% of eyes had RK or astigmatic keratotomy (AK). Among the 29 eyes with ALK alone, 86% had 20/40 or better uncorrected visual acuity, with mean uncorrected acuity and mean corrected acuity of 0.69 +/- 0.21 (20/30) and 0.95 +/- 0.10 (20/21), respectively; 72% of eyes were within 1.00 D of emmetropia and 90%, within 2.00 D. In 4%, astigmatism increased more than 1.00 D from the preoperative value and 4% of eyes (5/128) had persistent irregular astigmatism. Four percent of eyes (5/128) had overcorrection, with a final spherical equivalent greater than +1.00 D. Epithelial growth in the interface requiring surgical removal occurred in 2% of cases. One eye with residual myopia from a previous RK lost the cap after ALK. A homologous donor graft was performed, which resulted in 20/30 uncorrected visual acuity. Best corrected visual acuity of two lines or more was lost in 6.3% of eyes (8/128). This was caused by irregular astigmatism in 63% of cases.

CONCLUSIONS

The results of our initial experience indicate that ALK is a reasonably safe, effective, and predictable procedure for correction of high myopia and myopia following previous RK. With additional enhancement with RK/AK, good visual and refractive outcome can be expected.