Lamellar Keratoplasty for Hyperopia

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.

The thin-flap LASIK technique

PURPOSE

To determine if LASIK using a 130-microm microkeratome head (thin-flap LASIK) is as visually effective and safe as when using a 160-microm head.

METHODS

A study was performed comparing postoperative day 1 uncorrected visual acuity (UCVA) and flap complications in eyes undergoing myopic LASIK with a 130-microm head versus a 160-microm head using the BD K-3000 microkeratome (BD Ophthalmic Systems, Waltham, Mass).

RESULTS

The mean preoperative myopia in the 155 eyes of 80 patients in the 130-microm head group was -5.00+/-2.53 diopters (D) compared to -3.78+/-1.73 D in the 279 eyes of 148 patients in the 160-microm head group. The groups were otherwise similar in terms of age, preoperative cylinder, and best spectacle-corrected visual acuity. The geometric mean postoperative day 1 UCVA was 20/25 in the 130-microm head group compared to 20/26 in the 160-microm head group. The only flap complication in the series was a single partial flap in the 160-microm head group.

CONCLUSIONS

LASIK with a 130-microm head (thin-flap LASIK) is as visually effective and safe as when using a 160-microm head with the BD K-3000 microkeratome.

Changes of posterior corneal astigmatism and tilt after myopic laser in situ keratomileusis

PURPOSE

The purpose of this study was to assess the changes of posterior corneal astigmatism and tilt after laser in situ keratomileusis (LASIK) and to correlate these changes with the amount of correction and the residual stromal bed thickness.

METHODS

This prospective nonrandomized (self-controlled) comparative trial included 57 eyes from 14 females and 15 males, whose mean age (+/- standard deviation [SD]) at the time of surgery was 33 +/- 9 years (range, 19-53), with a spherical equivalent (SEQ) of -1.00 to -15.50 (mean, -5.07 +/- 2.81) diopters (D). All LASIK procedures were accomplished with the Keratom II Coherent-Schwind excimer laser and the Moria Model One microkeratome (150-microm head). Subjective refractometry, Orbscan slit-scanning corneal topography analysis, and pachymetry were performed before and 3 months after LASIK for myopia (n= 35; -1.00 to -15.50 D [mean, -4.75 +/- 3.07]) or myopic astigmatism (n= 22; sphere, 0.00 to -9.75 D [mean, -4.75 +/- 2.36]; cylinder, -0.75 to -3.50 D [-1.68 +/- 0.86]). Intended ablation depth ranged from 12 to 108 (mean, 48 +/- 22) microm. Topographic raw data were decomposed into a set of Zernike polynomials as published in detail previously, and parameters for detection of asymmetric mechanical deformation of the cornea were derived. Posterior corneal astigmatism and tilt before and after LASIK were compared, and changes in these variables were correlated with the SEQ change (DeltaSEQ) and the residual corneal bed thickness (RBT).

RESULTS

The RBT after LASIK ranged from 186 to 373 (mean, 280 +/- 42) microm. Overall, astigmatism (0.19 +/- 0.07 D/0.22 +/- 0.13 D; p= 0.80) and tilt (3.58 +/- 0.35 degrees /3.65 +/- 0.48 degrees; p= 0.61) did not change significantly by 3 months after LASIK. In eyes with RBT < or =250 microm, the average change in astigmatism (0.05 +/- 0.11 versus 0.01 +/- 0.13 D; p= 0.46) and tilt (0.21 +/- 0.45 degrees versus 0.04 +/- 0.55 degrees; p= 0.30) was not greater than in eyes with RBT > 250 microm. Change in astigmatism (p= 0.19) and tilt (p= 0.56) did not correlate with the RBT during LASIK.

CONCLUSIONS

Zernike decomposition of topographic height data discloses that no significant asymmetric mechanical deformation of the posterior corneal curvature occurs after myopic LASIK. Further studies with long-term follow-up are needed to clarify whether this symmetry of the posterior corneal surface can indeed be preserved over time after LASIK if the RBT is < 250 microm.

Hyperopic laser-assisted in situ keratomileusis for radial keratotomy induced hyperopia

PURPOSE

To evaluate hyperopic laser in situ keratomileusis (H-LASIK) for radial keratotomy (RK)-induced hyperopia.

DESIGN

Noncomparative interventional retrospective nonconsecutive case series.

PARTICIPANTS

Sixty-nine eyes of 47 patients who had undergone RK and were seen with induced hyperopia.

METHODS

H-LASIK was performed with an excimer laser.

MAIN OUTCOME MEASURES

The mean refractive error, in spherical equivalents (SE), uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) before and after H-LASIK are reported. Safety was analyzed using a mean follow-up time of 6.6 plus minus 3.24 months.

RESULTS

Preoperative mean SE was +3.4 plus minus 1.6 diopters (D). Postoperative mean SE was -0.32 plus minus 1.2 D. A high percentage of eyes (79.7%; n = 55) were between plus minus1.0 D of emmetropia and 88% within plus minus 2.0 D. Preoperative BSCVA was 20/20 in 53.6% of eyes (n = 37) and 20/40 or better in 100% (n = 69). Postoperative BSCVA was 20/20 in 55% of eyes (n = 38) and 20/40 or better in 95.6% (n = 66) of eyes. Preoperative UCVA was less-than-or-equal20/50 in 52 cases (75.4%). Postoperative UCVA was 20/20 in 13 cases (18.8%) and greater-than-or-equal20/40 in 45 cases (65.2%). Four eyes lost 2 Snellen lines because of epithelial ingrowth in the interface (n = 3) and diffuse lamellar keratitis (Sands of the Sahara syndrome; n = 2). One of the eyes with Sahara syndrome also had epithelial ingrowth and flap necrosis. Thirteen eyes lost 1 Snellen line, and 50 eyes maintained or gained Snellen lines. The only intraoperative complication was incision opening (n = 8) while the flap was lifted; there were no further complications. These patients did not lose any Snellen lines of their BSCVA.

CONCLUSIONS

H-LASIK can be used successfully to correct RK-induced hyperopia.

Laser in situ Keratomileusis for Hyperopia and Hyperopic Astigmatism With the Nidek EC-5000 Excimer Laser

PURPOSE

We evaluated the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) for hyperopia and hyperopic astigmatism.

METHODS

A retrospective study was performed for 92 eyes of 62 consecutive patients to evaluate uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA) and manifest refraction before and 3 and 6 months after LASIK (Moria LSK-ONE microkeratome, Nidek EC-5000 excimer laser). Eyes were divided into groups: Group 1 (low hyperopia) for spherical correction of +1.00 to +3.00 D (22 eyes), Group 2 (low hyperopic astigmatism) for toric correction with spherical equivalent refraction of +1.00 to +3.00 D (18 eyes), Group 3 (moderate hyperopia) for spherical correction of +3.25 to +6.00 D (10 eyes), and Group 4 (moderate hyperopic astigmatism) for toric correction with spherical equivalent refraction between +3.25 and +6.00 D (18 eyes).

RESULTS

At 3 and 6 months after LASIK, 68 eyes (73.9%) were available for follow-up examination. Percentage of eyes with a spherical equivalent refraction within +/-0.50 D of emmetropia for Group 1 was 54.5% (12 eyes); Group 2, 50% (9 eyes); Group 3, 40% (4 eyes), and Group 4, 38.8% (7 eyes). UCVA > or =20/20 in Group 1 was 14% and in Groups 2, 3, and 4, 0%. One eye (5.5%) lost two lines of BSCVA.

CONCLUSION

LASIK with the Moria LSK-ONE microkeratome and the Nidek EC-5000 excimer laser reduced low and moderate hyperopia and was within +/-0.50 D of target outcome in approximately 50% of eyes. Undercorrection was evident in all groups. The procedure was safe.

Posterior corneal curvature changes after myopic laser in situ keratomileusis

OBJECTIVE

To assess the posterior corneal power and asphericity changes after myopic laser in situ keratomileusis (LASIK) and to correlate these changes with the amount of correction and the residual stromal bed thickness.

DESIGN

Prospective nonrandomized (self-controlled) comparative study.

PARTICIPANTS

Fifty-seven eyes of 14 women and 15 men, mean age at the time of surgery 33 +/- 9 (range, 19-53) years with a spherical equivalent (SEQ) of -1.00 to -15.50 (mean, -5.07 +/- 2.81) diopters (DI).

INTERVENTION

All procedures were performed with the Keratom II Coherent-Schwind excimer laser and and the Moria Model One microkeratome (150-microm head). Subjective refractometry, Orbscan slit scanning corneal topography analysis and pachymetry were performed before and 3 months after LASIK for myopia (n=35, -1.00 to -15.50 D, mean -4.75 +/- -3.07 D) or myopic astigmatism (n=22, sphere 0.00 to -9.75 D, mean -4.75 +/- 2.36 D; cylinder -0.75 to -3.50 D, mean -1.68 +/- 0.86 D). Intended ablation depth ranged from 12 to 108 (mean, 48 +/- 22) microm. Topographic raw data were decomposed into a set of Zernike polynomials as published in detail previously, and parameters potentially indicative for detection of a "mild keratectasia" were derived.

MAIN OUTCOME MEASURES

Posterior central corneal power and asphericity before and after LASIK were compared, and changes of these variables were correlated with the SEQ change (deltaSEQ)and the residual corneal bed thickness RBT).

RESULTS

The mean RBT after LASIK was 280 +/- 42 microm. Overall, change of posterior power (-6.28 +/- 0.22 D/ -6.39 +/- 0.23 D, P=0.02) was statistically significant and change of asphericity (0.98 +/-0.07/1.14 +/- -.20, P<0.0001) was highly significant. In eyes with RBT < or =250 microm, the average change of posterior central power (-0.20 +/- 0.10 D vs. -0.08 +/- 0.18 D) was significantly greater than in eyes with RBT >250 microm (P=0.003). The change of posterior corneal power correlated significantly with deltaSEQ (P=0.004) and the RBT (P=0.002).

CONCLUSIONS

Increased negative keratometric diopters and oblate asphericity of the posterior corneal curvature suggest that mild "keratectesia" of the cornea may be common early after LASIK. Further stuudies with longer follow-up are required to clarify whether this biomechanical deformation is progressive and whether a residual bed thickness of >250 microm can completely prevent it.

Laser in situ Keratomileusis for the Correction of Hyperopia From +0.50 to +11.50 Diopters With the Keracor 117C Laser

PURPOSE

To evaluate excimer laser in situ keratomileusis (LASIK) for the correction of hyperopia.

METHODS

We reviewed retrospectively the medical records of 46 patients treated with LASIK for hyperopia. All patients had a complete ophthalmologic evaluation. The corneal bed was ablated using the Bausch & Lomb Chiron Keracor 117C excimer laser to create a paracentral annular ablation under a nasally hinged 160-microm corneal flap with the Chiron Automatic Corneal Shaper microkeratome. Follow-up was a minimum of 6 months.

RESULTS

Eighty eyes of 46 patients (23 males and 23 females) were included. Age ranged from 18 to 65 years (mean, 42 yr). The range of preoperative spherical equivalent refraction was +0.50 to +11.50 D (mean, +3.40 D). Mean postoperative spherical equivalent refraction at 6 months was +0.26 D. Six months after surgery, 35 eyes (44%) achieved uncorrected visual acuity of 20/20 or better and 78 eyes (97.5%) achieved 20/40 or better. Forty-six eyes (58%) had a postoperative spherical equivalent refraction within +/-0.50 D of attempted correction, and 67 eyes (84%) were within +/-1.00 D of attempted correction. When using the Bausch & Lomb Chiron Keracor 117C excimer laser to correct hyperopia, eyes with a spherical equivalent refraction less +2.00 D should be overcorrected by 25%, +2.00 to +4.00 D by 30%, and over +4.00 by 40%. The positive cylinder should be overcorrected by 10%.

CONCLUSIONS

LASIK was safe and effective in the treatment of hyperopia from +0.50 to +11.50 D. Regression following LASIK for hyperopia remains a problem. A special nomogram was required to achieve results comparable with those for myopia.

Laser in situ Keratomileusis for the Correction of Hyperopia From +1.25 to +5.00 Diopters With the Technolas Keracor 117C Laser

PURPOSE

To assess the efficacy, predictability, stability, and safety of laser in situ keratomileusis (LASIK) in patients with hyperopia and to evaluate the visual and refractive results of the procedure.

METHODS

LASIK was performed on 85 eyes of 53 patients for correction of hyperopia, with a preoperative mean manifest spherical equivalent refraction of +3.31 +/- 0.69 D (range, +1.25 to +5.00 D) and mean refractive astigmatism of +0.91 +/- 1.06 D (range, 0 to +3.00 D). The Carriazo-Barraquer (Moria) manual microkeratome was used to create the corneal flap, and laser ablation was performed using the Technolas Keracor 117C excimer laser with an ablation zone diameter of 6.0 mm and a transition zone diameter to 9.0 mm. Follow-up was 12 months for all patients.

RESULTS

Refraction was stable by 3 months after surgery. At 1 year after LASIK, the mean manifest spherical equivalent refraction was +0.43 +/- 0.57 D (range, -1.25 to +2.00 D) and refractive astigmatism was reduced to a mean of 0.36 +/- 0.30 D (range, 0 to 1.00 D). Fifty-two eyes (61.2%) had a manifest spherical equivalent refraction within +/- 0.50 D of emmetropia, and 76 eyes (89.4%) were within +/- 1.00 D. Uncorrected visual acuity was 20/20 in 21 eyes (24.7%) and 20/40 or better in 79 eyes (92.9%). Spectacle-corrected visual acuity was reduced by two lines in one eye (1.2%) and improved by two lines in five eyes (5.9%). There were no significant complications.

CONCLUSION

LASIK was an effective, safe, and predictable procedure for the correction of hyperopia up to +5.00 D and hyperopic astigmatism up to +3.00 D with the Technolas Keracor 117C excimer laser. The large size of the corneal flap obtained by the Carriazo-Barraquer (Moria) manual microkeratome facilitated laser ablation entirely in the exposed corneal stromal bed.

Advances in refractive surgery: 1975 to the present

PURPOSE

To review the major advances in the field of refractive surgery occurring over the past 25 years.

METHODS

Literature review.

RESULTS

The major developments in refractive surgery over the past 25 years are reviewed.

CONCLUSIONS

The past 25 years have witnessed great changes in refractive surgery. As a result of advancements in technology, instrumentation, and technique, we have seen improvements in the treatment of all types of ametropias. In this article, we review some of the successes and failures of the past quarter-century.

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.

Lasso procedure to revise overcorrection with radial keratotomy

PURPOSE

To report three patients who underwent the lasso procedure to revise overcorrection with radial keratotomy.

METHODS

Case report and review of the literature.

RESULTS

Four eyes of three patients who had undergone radial keratotomy with resultant hyperopic overcorrection underwent a lasso procedure. Before the procedure, average cycloplegic refraction spherical equivalent was +3.656 +/- 1.352 diopters, and average manifest refraction spherical equivalent was +2.250 +/- 0.621 diopters. A 10.0 monofilament nylon suture was placed in a circumferencial manner through the corneal stroma and overlapping the old radial keratotomy incisions. At 1 month postoperatively, best-corrected visual acuity was 20/20 in all four eyes, with average cycloplegic refraction spherical equivalent +0.438 +/- 1.423 diopters and average manifest refraction spherical equivalent -0.156 +/- 1.147 diopters. Mean delta cycloplegic refraction spherical equivalent was 3.219 +/- 1.724.

CONCLUSIONS

The lasso procedure provides an immediate solution for symptomatic overcorrected hyperopic eyes after radial keratotomy. Predictability and long-term stability necessitate further follow-up.

LASIK for hyperopia and hyperopic astigmatism--results of a pilot study

Laser-assisted in situ keratomileusis (LASIK) was evaluated in hyperopia and hyperopic astigmatism. LASIK was safe and effective in spherical hyperopia up to +5 D and acceptable in toric hyperopia up to +5 D but results were poor in hyperopia of more than +5 D.

Posterior Chamber Phakic Intraocular Lens for Hyperopia of +4 to +11 Diopters

PURPOSE

To examine the efficacy, predictability, stability, and safety of posterior chamber phakic intraocular lens (IOL) implantation in eyes with high hyperopia.

METHODS

We analyzed the results of 24 eyes that received a posterior chamber hydrogel-collagen plate phakic IOL (Staar Collamer Implantable Contact Lens, ICL) for the correction of hyperopia with the goal of emmetropia. Mean follow-up was 8.4 months (range, 1 to 18 mo).

RESULTS

The mean preoperative spherical equivalent refraction was +6.51 +/- 2.08 D (range, +3.75 to +10.50 D). Mean postoperative spherical equivalent refraction at last examination was -0.39 +/- 1.29 D (range, +1.25 to -3.88 D), with 79% (19 eyes) within +/-1.00 D and 58% (14 eyes) within +/-0.50 D of emmetropia. Postoperative uncorrected visual acuity at last examination was 20/20 or better in 8% (two eyes) and 20/40 or better in 63% (15 eyes). A gain of two or more lines of spectacle-corrected visual acuity was seen in two eyes (8%) at last examination. One eye (4%) lost two or more lines of spectacle-corrected visual acuity due to progressive neovascular glaucoma initiated by early postoperative pupillary block.

CONCLUSION

Posterior chamber phakic IOL implantation with the Staar Collamer plate lens is an effective method for correcting high hyperopia. Large, patent iridotomies are important in hyperopic eyes to lower the risk of postoperative pupillary block. Improved phakic IOL power calculation formulas will refine predictability of refractive outcome.

Laser in situ Keratomileusis to Correct Hyperopia from +4.25 to +8.00 Diopters

OBJECTIVE

To evaluate the efficacy and predictability of laser in situ keratomileusis (LASIK) for hyperopia in a prospective study of 54 eyes of 29 patients.

METHODS

Before LASIK, 44 eyes (81.48%) had a spectacle-corrected visual acuity of 20/20 or better, and 54 eyes (100%) had 20/40 or better. Surgery was performed under topical anesthesia using the Keracor 116 excimer laser and Chiron automated corneal shaper. Mean follow-up was 19 months.

RESULTS

Mean baseline uncorrected hyperopia was +6.50 +/- 1.33 D (range, +4.25 to +8.00 D). Mean uncorrected manifest spherical equivalent refraction was +0.44 +/- 1.95 D at 18 months after LASIK. Twenty-one eyes (38.8%) were within +/-0.50 D of emmetropia, 41 eyes (75.92%) were within +/-1.00 D, and 47 eyes (87.03%) were within +/-2.00 at 18 months after LASIK. Uncorrected visual acuity was 20/20 or better in eight eyes (14.81%) and 20/40 or better in 36 eyes (66.66%) 18 months after LASIK. Regression and undercorrection of more than 2.00 D occurred in seven eyes (12.9%) between the 3 and 6 month examinations; three of these seven eyes (42.8%) required retreatment to correct residual hyperopia. Three eyes (6.8%) lost two or more lines of spectacle-corrected visual acuity.

CONCLUSION

Excimer laser keratomileusis in situ with the Keracor 116 appears to be an effective and safe procedure to decrease low and moderate hyperopia, but the predictability of the procedure needs improvement.

Factors influencing the outcome of hyperopic lamellar keratoplasty

PURPOSE

To determine which factors affect the refractive outcome of hyperopic lamellar keratoplasty.

SETTING

Jules Stein Eye Institute and Department of Ophthalmology, UCLA, Los Angeles, California, USA.

METHODS

This retrospective study comprised 38 consecutive eyes of 25 patients with naturally occurring hyperopia who had automated lamellar keratoplasty by one surgeon. Mean attempted correction was 3.80 diopters (D) (range of 1.50 to 6.00 D); 34 eyes were followed for 3 months. The effect of applanation lens diameter, keratometry, age, corneal thickness, absolute flap thickness in microns, thickness of the posterior lamellae in microns, and flap thickness as a percentage of corneal thickness were determined using multivariate linear regression.

RESULTS

With current nomograms, mean undercorrection 3 months after hyperopic lamellar keratoplasty was 1.26 D +/- 0.91 (SD); 14 of 34 eyes were within +/- 1.00 D of the attempted correction. The best predictive factors of achieved correction were applanation lens diameter and absolute flap thickness in microns, which accounted for 54% of the variability in outcome. Keratometry, corneal thickness, and flap thickness as a percentage of corneal thickness had no significant additional predictive value.

CONCLUSION

The refractive outcome of hyperopic lamellar keratoplasty was primarily determined by applanation lens diameter and absolute flap thickness in microns. Current nomograms suggest that flap thickness as a percentage of corneal thickness is a major determinant of effect, but this factor appears unimportant to the refractive effect of hyperopic lamellar keratoplasty. We hypothesize that it is slight swelling of the anterior corneal stroma rather than the bulging of the posterior cornea that causes the hyperopic correction in hyperopic lamellar keratoplasty.