Comparison of Intersecting Trapezoidal Keratotomy and Arcuate Transverse Keratotomy in the Correction of High Astigmatism

Advances in technologies for laser-assisted in situ keratomileusis (LASIK) surgery

Laser-assisted in situ keratomileusis (LASIK) has become the most widely used form of refractive surgery today. The objective of this surgical technique is to modify the anterior corneal shape by ablating tissue from the stroma by means of the excimer laser after creating a hinged corneal flap. This way, we are able to change the refractive status of the patient, providing better unaided vision. Continuous improvements in the original technique have made the surgical procedure safer, more accurate and repeatable. These progressions are due to the development of novel technologies that are the responsible for new surgical instrumentation, which makes the surgical procedure easier for the surgeon, and better excimer laser ablation algorithms, which increase the optical quality of the ablation and thus the safety of the vision correction procedure. This article aims to describe the more relevant advances in LASIK that have played an important role in the spread and popularity of this technique.

Cataract Surgery With Toric Intraocular Lenses Can Optimize Uncorrected Postoperative Visual Acuity in Patients With Marked Corneal Astigmatism

PURPOSE

To study the change in visual acuity and refraction after cataract surgery using a toric posterior chamber intraocular lens in patients with astigmatism after penetrating keratoplasty.

METHODS

A retrospective case note analysis of cataract surgery involving toric lens implants performed at the Norfolk and Norwich University Hospital was conducted. The pre- and postoperative visual acuities and refractions were recorded.

RESULTS

Seven consecutive patients are described (5 men and 2 women) with a mean age of 62 years. They all underwent penetrating keratoplasty, and in every case, all sutures were removed (mean, 11.2 months before cataract surgery). A marked improvement in both unaided visual acuity and astigmatism was shown after the procedure. The average preoperative unaided acuity was 6/120 (range, 6/24 to counting fingers) compared with a postoperative unaided visual acuity average of 6/15 (6/9-6/24). The average preoperative cylinder was 10.12 D (range, 3.40-17.89 D); postoperatively, this fell to 2.75 D (range, 0.75-4.25).

CONCLUSIONS

Cataract surgery with toric intraocular lenses allows the correction of high degrees of regular corneal astigmatism. We discussed the potential advantages and complications of performing toric lens cataract surgery as a secondary procedure.

Linear–long incisions with a small optical zone for the correction of astigmatism in older patients

PURPOSE

To evaluate the efficacy of astigmatic keratotomy (AK) by paired linear (transverse)-long incisions within a small optical zone in older patients with 3.00 diopters (D) or more of astigmatism who are intolerant of contact lenses, spectacles, or both.

DESIGN

Prospective, noncomparative case series.

PARTICIPANTS

Twenty-one eyes (20 patients; age range, 58-87 years) treated at clinics of the Taipei Veterans General Hospital were included in this study.

METHODS

Paired linear incisions (90 degrees in length) with a central optical zone (OZ) of 4.5 mm were made to correct high astigmatism in older patients. The incisions were 80% of the corneal thickness and parallel to the axis of the steepest cylinder.

MAIN OUTCOME MEASURES

Refraction, keratometry, corneal topography, and visual acuity with and without correction were measured as the outcome indicators.

RESULTS

The mean course of the stabilization of corneal curvature was 1.8 months. Significant improvement from a preoperative corneal astigmatism of 4.52+/-1.39 D to a postoperative value of 1.82+/-0.88 D (P<0.0001) was shown. Marked axis deviations of more than 30 degrees were observed in 5 cases and corneal perforation was observed in 1 case. When the corneal curvature stabilized, uncorrected visual acuity was improved by 2 lines or more in 15 eyes (71.4%). Spherical equivalents and best-corrected visual acuity did not change significantly. Postoperative glare was absent in all patients.

CONCLUSIONS

We conclude that AK by linear-long incisions extending from a small OZ is effective and safe for correcting astigmatism.

Correction of astigmatism after penetrating keratoplasty by relaxing incision with compression suture: a comparison between the guiding effect of photokeratoscope and of computer-assisted videokeratography

PURPOSE

To report the results of astigmatism correction after penetrating keratoplasty by relaxing incision with compression suture and to compare the guiding ability of a photokeratoscope with that of computer-assisted videokeratography.

METHODS

In the two independent retrospective series, 11 eyes received a relaxing incision with compression suture guided by photokeratoscope or computer-assisted videokeratography.

RESULTS

In 22 eyes, the relaxing incision with compression suture showed a mean 56% reduction in astigmatism and 78% reduction in vector-calculated astigmatism. The mean postoperative visual acuity was improved 2.92 Landolt lines. The 11 eyes in which treatment was guided by photokeratoscope demonstrated a mean reduction of 50% and 71% in astigmatism and vector-calculated astigmatism, respectively, and visual acuity increased 2.44 Landolt lines. Another 11 eyes in which treatment was guided by computer-assisted videokeratography achieved a mean reduction of 67% and 90% in astigmatism and vector-calculated astigmatism, respectively, together with 3.41 Landolt lines improvement in visual acuity. There were no significant differences in astigmatism correction and visual acuity improvement between the two groups.

CONCLUSION

The results demonstrate that the relaxing incision with compression suture is an effective and safe procedure for correcting high astigmatism after penetrating keratoplasty. The two instruments have no significant difference in their guiding capacities for this procedure.

Undersurface ablation of the flap for laser in situ keratomileusis retreatment

OBJECTIVE

To develop a novel technique, undersurface ablation of the flap (UAF), for laser in situ keratomileusis (LASIK) retreatment in eyes with insufficient posterior stroma.

DESIGN

Noncomparative, interventional case series.

PARTICIPANTS

From 30 eyes examined, 25 eyes with a spherical equivalent residual refraction between -0.75 and -3.25 diopters (D) and astigmatism between 0.0 and -1.5 D were prospectively included in the study. In these eyes, calculated postenhancement flap thickness was >150 micro m using micropachymetric optical coherence tomography (OCT), whereas with further ablation of the bed, posterior stromal thickness would have been <250 micro m. Primary LASIK procedures had been performed with the Hansatome microkeratome.

INTERVENTION

The flap was lifted and the eye deviated downward, so that the corneal visual axis mark aligned with the laser beam. Mirror pattern ablations with an optical zone of 5 mm were performed on the flap stroma using either the Summit Apex Plus excimer laser or the Technolas Keracor 217 spot-scanning excimer laser. New axis orientation for toric ablations was calculated with the formula: beta = 180 degrees - alpha.

MAIN OUTCOME MEASURES

Refraction, visual acuity, OCT pachymetry, tangential videokeratography, and patient satisfaction.

RESULTS

The average follow-up was 6.36 +/- 2.64 months (range, 3-12 months). Mean preenhancement spherical equivalent (-2.05 +/- 0.75 D) was reduced to -0.19 +/- 0.38 D at the last visit (P = 0.001). Mean cylinder decreased from -0.48 +/- 0.53 D before retreatment to -0.23 +/- 0.28 D at the last follow-up (P = 0.003). Best-corrected visual acuity worsened by 1 line in two eyes (8%), and no eye lost 2 or more lines. Satisfactory globe stabilization and stromal smoothness during ablation were more difficult to achieve than with conventional LASIK enhancements. The average central flap thickness before UAF, 187 +/- 13 micro m, decreased to 164 +/- 12 micro m after 1 month (P = 0.001). No keratectasia developed. Finally, 92% of cases were satisfied with surgery compared with 48% before UAF retreatment (P = 0.001).

CONCLUSIONS

UAF retreatment for low residual refractive errors after LASIK in eyes with sufficient flap stroma seems to be effective and may prevent future keratectasia.

Correction of high astigmatism with astigmatic keratotomy combined with laser in situ keratomileusis

PURPOSE

To evaluate the efficacy, predictability, and stability of a combined procedure, arcuate keratotomy and laser in situ keratomileusis (LASIK), for the correction of high astigmatism.

SETTING

Instituto de Microcirugía Ocular (IMO), Barcelona, Spain.

METHODS

Fifteen eyes of 11 patients with naturally occurring astigmatism (NOA) (86. 66%) or surgically induced astigmatism (SIA) (13.34%) between -3.00 and -8.00 diopters (D) who had astigmatic keratotomy were studied. The patients had a secondary procedure, LASIK, to correct the residual refractive error.

RESULTS

Mean baseline spherical equivalent refraction was -2.47 D +/- 3.69 (SD) and mean refractive cylinder, -4.59 +/- 1.66 D. Twelve months after LASIK, mean spherical equivalent was -0.09 +/- 1.50 D and the mean refractive cylinder, -1. 21 +/- 1.07 D. The mean cylindrical correction attempted in the NOA group was -4.05 +/- 1.19 D and in the SIA group, -7.00 +/- 1.41 D. Postoperatively, the values were -1.50 +/- 1.17 D and -1.62 +/- 0.17 D, respectively. Twelve months after LASIK, the uncorrected visual acuity (UCVA) was 0.5 +/- 0.1. The UCVA in the NOA group (0.50 +/- 0. 08) was better than in the SIA group (0.32 +/- 0.10). The efficacy index was 0.96 overall. Best corrected visual acuity deteriorated by 1 Snellen line in 1 case (6.6%) but improved by 1 and 2 Snellen lines in 4 cases (26.6%) and 2 cases (13.3%), respectively. All procedures were completed without adverse reactions intraoperatively or postoperatively.

CONCLUSION

This combined technique was effective in the treatment of high astigmatism, with excellent results compared with the results of each procedure alone. Because of its high predictability, we strongly recommend the technique in cases with astigmatism higher than 3.0 D, particularly in those with astigmatism higher than 5.0 D.

Surgical correction of postkeratoplasty astigmatism with the Hanna arcitome

PURPOSE

To report the results of arcuate keratotomy performed with the Hanna arcitome in patients with postkeratoplasty astigmatism.

SETTING

Department of Ophthalmology, Saint-Antoine Hospital, Paris VI University, Paris, France.

METHODS

This retrospective study comprised 22 eyes (22 patients) with postkeratoplasty astigmatism. Paired symmetrical arcuate keratotomy was performed with the Hanna arcitome. Outcome measures included refraction, videokeratography, and keratometry.

RESULTS

At 6.6 months +/- 8.9 (SD) after surgery, the mean increase in best spectacle-corrected visual acuity (BSCVA) was 2.1 +/- 2.4 lines. Thirteen eyes gained 2 lines or more of BSCVA, and 15 gained 3 lines or more of uncorrected visual acuity. Two patients had a decrease in BSCVA: 1 had lens opacification unrelated to arcuate keratotomy and 1, increased corneal irregularity. Mean refractive astigmatism was 6.94 +/- 2.11 diopters (D) preoperatively and 3.85 +/- 1.95 D postoperatively (P < .01). Mean change in keratometric astigmatism was -51 +/- 36%. Astigmatism decreased in 21 eyes as measured by manifest refraction, keratometry, and videokeratography; it increased in 1 cornea with a microperforation.

CONCLUSIONS

The results of arcuate keratotomy performed with the Hanna arcitome were comparable to those with freehand relaxing incisions. The instrument made safer and more uniform arcuate incisions than a freehand technique.

Surgical control of late postkeratoplasty astigmatism with or without the use of computerized video keratography: a prospective, randomized study

OBJECTIVE

To assess the effectiveness of computerized videokeratography (CVK) in refining the surgical design and in improving predictability of surgical correction of postkeratoplasty astigmatism.

DESIGN

A prospective, controlled, randomized, clinical trial.

PARTICIPANTS

A total of 31 postkeratoplasty eyes, divided into 2 groups (group A, 16 eyes; group B, 15 eyes), with more than 4 diopters (D) of disabling astigmatism were studied.

INTERVENTION

All eyes were treated with a combination of arcuate relaxing incisions and compression sutures. The surgical plan in group A was based on topographic information, whereas in the control group B, the surgical plan was based on information obtained by refraction and keratometry alone.

MAIN OUTCOME MEASURES

Change in the surgical plan induced by the CVK information, astigmatism, topographic patterns, and factors associated with outcome were measured.

RESULTS

In all 16 cases of group A, the use of CVK changed some aspect of the surgical plan. At 12 months after surgery, both groups showed a significant net reduction (P = 0.001) of baseline astigmatism. However, the reduction (47% and 41 % for groups A and B, respectively) did not differ significantly between the two groups. The topographic astigmatism at 12 months measured 4.24 +/- 0.71 D in group A and 5.60 +/- 0.51 D in group B (P = 0.139). Significant differences between the two groups at 12 months were seen only for keratometric astigmatism (3.60 +/- 0.81 D in group A vs. 5.77 +/- 0.52 D in group B, P = 0.035) and refractive astigmatism (2.34 +/- 0.37 D in group A vs. 4.88 +/- 0.52 D in group B, P = 0.000). The mean vector surgical effect was 91 % for group A and 70% for group B. Regular astigmatism patterns had a greater benefit from surgery than irregular patterns (P = 0.008). Previous refractive surgery was associated with less-favorable outcome (P = 0.045).

CONCLUSIONS

The current study indicates that the use of CVK provides a benefit compared to keratometry and refraction alone in the planning and outcome of surgical treatment for high postgraft astigmatism.