Management of post-keratoplasty astigmatism

Post-keratoplasty astigmatism remains a challenge for corneorefractive surgeons. While maintaining a healthy graft is the most crucial issue in keratoplasty procedures, astigmatism is a limiting factor in the visual rehabilitation of otherwise successful corneal grafts. The management of post-keratoplasty astigmatism takes place at 2 stages: when sutures are still present at the graft-host junction and when all sutures have been removed. Excessive suture-in post-keratoplasty astigmatism is usually managed by selective suture manipulation, ie, suture adjustment and/or suture removal along the steep meridian of astigmatism. A small amount of suture-out post-keratoplasty astigmatism can be managed by spectacles. Higher magnitudes of astigmatism can be addressed by contact lenses or surgical intervention, such as relaxing and compressing procedures. Laser lamellar refractive surgery can also be used to manage post-keratoplasty astigmatism, and toric phakic intraocular lenses have recently been recommended. In this review, we discuss the etiology and management of post-keratoplasty astigmatism and provide recommendations and tips to minimize it.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Long-term refractive stability following combined astigmatic keratotomy and phakoemulsification

BACKGROUND

To determine whether combined astigmatic keratotomy and cataract surgery induces a sustained reduction in astigmatism.

METHODS

Patients who had previously undergone combined cataract surgery and astigmatic keratotomy for naturally occurring astigmatism were identified and their notes reviewed. Mean final follow-up was 34 months (30-42 months). Fourteen eyes of 11 patients were eligible for study. Arcuate corneal incisions had been employed using the Buzard nomogram. Using power vector analysis, the post-operative refractive change at 6 months and final follow-up was determined.

RESULTS

The mean preoperative manifest cylindrical refractive error was 2.88 D (1.50-5.50 D). The mean postoperative manifest cylindrical refractive error was 1.89 and 1.79 D at 6 months and final follow-up, respectively. Power vector analysis demonstrated a significant postoperative reduction in refractive blur at 6 months and final follow-up (P = 0.006, P = 0.004, respectively): mean preoperative blur strength was 2.90 D and mean postoperative blur strength was 1.33 and 1.25 D at 6 months and final follow-up, respectively. Sustained postoperative reduction in astigmatism was noted in 12 of 14 eyes at final follow-up.

CONCLUSIONS

Astigmatic keratotomy is a well-established treatment for astigmatism. In this series, the refractive benefit from combined astigmatic keratotomy and cataract surgery is maintained for several years. No surgical complications were observed.

Mechanized astigmatic arcuate keratotomy with the Hanna arcitome for astigmatism after keratoplasty

PURPOSE

To report the results of correction of post-keratoplasty astigmatism by arcuate keratotomy performed with the Hanna arcitome (Moria).

SETTING

Service 5, Hôpital des 15-20, Paris VI University, Paris, France.

METHODS

Forty eyes operated on for post-keratoplasty astigmatism using the Hanna arcitome were retrospectively studied. Paired symmetrical arcuate keratotomies were performed on the graft button. Mean follow-up was 10.8 months +/- 11.2 (SD). Outcome measures included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and subjective refraction. For statistical analysis, visual acuity data were transformed into logMAR units. The refractive data were analyzed using the Alpins method.

RESULTS

By a mean of 10.8 +/- 11.2 months after surgery, the UCVA had improved a mean of 0.28 +/- 0.46 lines, which was significant (P = .013). The BSCVA remained stable. The mean subjective cylinder was 8.84 +/- 3.00 diopters (D) preoperatively and 4.88 +/- 2.50 D postoperatively (P<.001). The changes in postoperative subjective cylinder values correlated with preoperative cylinder values (r(s) = 0.584; P<.0001). The subjective axis was modified by 20 degrees or less in 27 eyes (67.5%). The mean surgically induced astigmatism was 8.07 +/- 3.83 D and the mean correction index, 0.96 +/- 0.46. One microperforation occurred and required suturing. Incisions were off center in 1 case, and 2 patients had an allograft rejection after the procedure.

CONCLUSIONS

Arcuate keratotomy performed with the Hanna arcitome was effective in reducing post-keratoplasty astigmatism. The device enabled safer, easier arcuate incisions than with manual techniques. However, predictability and efficacy could be improved by a more accurate nomogram.

Standardized arcuate keratotomy for postkeratoplasty astigmatism

PURPOSE

To assess the effect of standardized, paired arcuate keratotomy (AK) on the change in astigmatism in postkeratoplasty eyes.

SETTING

Moorfields Eye Hospital, London, United Kingdom.

METHODS

A retrospective review was conducted of 20 eyes of 19 patients having the same AK procedure regardless of the magnitude of the preoperative astigmatism. Each eye had a pair of 60-degree arc length incisions placed in the corneal stroma. The incisions were 600 mum deep and 6.0 mm apart. The preoperative and postoperative refractions and complications were analyzed. Astigmatic change was analyzed without regard to axis, as surgically induced refractive change, and using a modified polar plot of change in astigmatism.

RESULTS

The mean cylinder was reduced from -10.99 diopters (D) +/- 4.26 (SD) to -3.33 +/- 2.18 D. There was no significant change in the mean spherical equivalent. There was a strong correlation between the magnitude of the preoperative cylinder and the magnitude of the change in astigmatism (R2 = 0.76). In 3 eyes, the surgically induced axis of astigmatism was more than 15 degrees from that expected.

CONCLUSIONS

In postkeratoplasty eyes, the change in the magnitude of astigmatism induced by standardized AK was proportional to the preoperative magnitude of astigmatism. Arcuate nomograms for congenital astigmatism have no role in the management of astigmatism in postkeratoplasty eyes.

Refractive outcomes after arcuate keratotomy using the Terry astigmatome

PURPOSE

To investigate the refractive outcomes after arcuate keratotomy for astigmatism.

SETTING

Uludag University, Faculty of Medicine, Department of Ophthalmology, Bursa, Turkey.

METHOD

Sixteen eyes of 11 patients with astigmatism had arcuate keratotomy using the Terry astigmatome. The mean age of the patients was 36 years +/- 10 (SD). All patients received preoperative and postoperative ophthalmic examinations consisting of best spectacle-corrected (BSCVA) and uncorrected (UCVA) visual acuities, corneal topography, and ultrasonic pachymetry. Surgery was performed using topical anesthesia of oxybuprocaine 0.1% eyedrops. The Terry astigmatome was selected by the mean paracentral (estimated incision area) corneal thickness. All patients received topical ofloxacin 0.3% and topical diclofenac 0.1% eyedrops postoperatively.

RESULTS

The mean corneal astigmatism was -4.0 +/- 1.1 diopters (D) (range -2.2 to -6.0 D) preoperatively and -1.8 +/- 0.8 D (range -0.6 to -3.0 D) postoperatively. The mean surgically induced corneal astigmatism was 2.5 +/- 0.6 D. The mean UCVA (logMAR) was 0.74 +/- 0.25 preoperatively and 0.18 +/- 0.23 1 week postoperatively, and the mean BSCVA (logMAR) was 0.19 +/- 0.24 and 0.19 +/- 0.23, respectively. There were no intraoperative or postoperative complications.

CONCLUSION

Arcuate keratotomy using the Terry astigmatome was a safe and reliable treatment for corneal astigmatism.

Limbal relaxing incisions in congenital astigmatism: 6 month follow-up

PURPOSE

To evaluate the effectiveness of limbal relaxing incisions (LRIs) for correcting naturally occurring astigmatism.

SETTING

Ankara Hospital, Ankara, Turkey.

METHODS

This prospective analysis of the results of the first LRIs in 22 eyes of 13 patients with congenital astigmatism was done using a modified Gills nomogram and was based on preoperative refractive astigmatism determined by manifest and cycloplegic refractions. There were no adjustments based on sex or age.

RESULTS

An absolute decrease of 0.91 diopter (D) (44%) in mean astigmatism was achieved after 6 months in 22 eyes. The mean uncorrected visual acuity (logMAR) increased from 0.42 to 0.26 from preoperatively to 6 months postoperatively. No patient lost best corrected visual acuity. Most regression occurred in eyes with more than 3.50 D of astigmatism and between the first and third postoperative months.

CONCLUSION

Limbal relaxing incisions are a practical, simple, and forgiving approach for the correction of lower degrees of astigmatism.

Opposite clear corneal incisions to correct pre-existing astigmatism in cataract surgery

In cataract surgery, the clear corneal incision (CCI) has a small flattening effect on corneal curvature, which can be used to reduce pre-existing astigmatism (PEA). Adding an identical, penetrating CCI opposite the first one can enhance the flattening effect. The paired opposite CCIs (OCCIs) are placed on the steepest meridian axis to flatten it. One CCI is used to perform cataract surgery, and the opposite CCI is made to enhance the flattening effect on the cornea to modulate PEA. During the past 12 months, we have used 2.8 to 3.5 mm OCCIs in 33 eyes with PEA greater than 2.00 diopters (D) having cataract surgery. The mean astigmatism correction achieved with this technique was 2.06 D. This technique is simple and effective and yields stable results that rival those of arcuate keratotomy. The OCCI technique has a potential application for the correction of astigmatism in general refractive surgery. Opposite clear corneal incision nomograms with variables such as width, length, and distance from the limbus will be needed for future applications.

Implantation of a toric poly(methyl methacrylate) intraocular lens to correct high astigmatism

A 57-year-old man experienced a decrease in visual function because of cataract formation. Corneal astigmatism was 13.4 diopters (D) because he had had a penetrating keratoplasty 27 years before. Cataract surgery was planned, and biometric data for toric intraocular lens (IOL) implantation were collected for the manufacture of a custom IOL. After phacoemulsification, a toric poly(methyl methacrylate) (PMMA) IOL of +19.0 D spherical and +12.0 D cylindrical power was implanted via a sclerocorneal tunnel incision. Three months postoperatively, corneal astigmatism was 14.3 D and best corrected visual acuity (BCVA), 20/25. Postoperative refraction (+1.5 -3.0 x 90) and BCVA remained stable for 7 months. No significant IOL rotation was observed. Implantation of a toric PMMA IOL corrected high corneal astigmatism. Toric IOL technology with high cylindrical power allows enhancement of IOL surgery.

Effect of astigmatic keratotomy on spherical equivalent: results of the Astigmatism Reduction Clinical Trial

PURPOSE

To determine the effect of astigmatic keratotomy on spherical equivalent, as measured by the coupling ratio and a new quantity, coupling constant.

METHODS

In a prospective multicenter study, subjects underwent arcuate keratotomy at a 7-mm optical zone by means of the Lindstrom nomogram for correction of astigmatism. One hundred fifty-seven eyes of 95 patients who had a follow-up examination 1 month postoperatively were studied. Mean preoperative refractive cylinder +/- SEM was 2.82 +/- 1.17 diopters. Coupling ratio was defined as the ratio of the flattening of the incised meridian to the steepening of the opposite meridian. Coupling constant was defined as the ratio of the change in spherical equivalent to the magnitude of the vector change in astigmatism. Coupling ratio, coupling constant, and change in spherical equivalent were calculated on the basis of change in refraction and keratometry.

RESULTS

On the basis of change in refraction, coupling ratio was 0.95 +/- 0.10 (mean +/- SEM) and coupling constant was -0.01 +/- 0.03, consistent with a minor shift in the spherical equivalent of -0.03 +/- 0.07 diopter. On the basis of change in keratometry, coupling ratio was 0.84 +/- 0.05 and coupling constant was -0.04 +/- 0.02, consistent with minor postoperative keratometric steepening of -0.10 +/- 0.04 diopter. Coupling ratio based on change in refraction was not statistically different from the coupling ratio predicted by the Gauss' law for inelastic domes (P = .370). Incision length and number, amount of achieved cylinder correction, age, and sex had no statistically significant effect on coupling ratio, coupling constant, and change in spherical equivalent.

CONCLUSIONS

Cornea behaved as an inelastic surface in response to arcuate keratotomy performed with the Astigmatism Reduction Clinical Trial study nomogram. On average, astigmatic keratotomy had a minimal effect on spherical equivalent refraction. There was variability, however, in coupling ratio, coupling constant, and change in spherical equivalent from eye to eye after astigmatic keratotomy. Caution is therefore advised when simultaneous correction of cylinder and spherical equivalent is planned.

Limbal relaxing incisions with cataract surgery

PURPOSE

To evaluate the effectiveness of limbal relaxing incisions (LRIs) for correcting corneal astigmatism during cataract surgery.

SETTING

Cullen Eye Institute, Houston, Texas, USA.

METHODS

In 12 eyes of 11 patients, cataract surgery was combined with LRIs. The LRIs were made according to a modified Gills nomogram and were based on preoperative corneal astigmatism determined with standard keratometry and computerized videokeratography (EyeSys Corneal Analysis System Version 3.2).

RESULTS

The mean preoperative keratometric cylinder was 2.46 +/- 0.81 diopters (D). At 1 month postoperatively, mean arithmetic reduction in keratometric cylinder was 1.12 +/- 0.74 D, and the with-the-wound (WTW) change (calculated by Holladay, Cravy, Koch vector analysis formula) was -0.70 +/- 0.44. From 1 day to 1 month postoperatively, there was 0.55 D of WTW regression with minimal change in the mean cylindrical axis. There were no overcorrections.

CONCLUSION

Limbal relaxing incisions are a practical, simple, and forgiving approach to the correction of astigmatism during cataract surgery.

Improved Technique of Circular Keratotomy for the Correction of Corneal Astigmatism

BACKGROUND

Based on Gauss' law governing the comparison of hyperbaric pressure in the eye and atmospheric pressure, the authors present a procedure to correct astigmatism. The present paper describes an improvement of a technique for circular keratotomy that was published previously.

METHODS

We present data on a consecutive series of 32 eyes with a mean corneal astigmatism of 4.66 diopters (D) (range -2.25 to -6.00 D) with a variety of clinical diagnoses. The astigmatic cornea was trephined with a diameter of 7 mm and a depth of 300 microns. After deepening of the trephination with a diamond knife to 550 microns over the steeper semimeridians, the intraocular pressure created a rounding of the cornea. The amount of astigmatic correction and extent of deepening were controlled intraoperatively with a keratoscope. No sutures were placed.

RESULTS

In 32 consecutive eyes, corrections were between 50 and 90% of the initial cylindrical values after 1 week to 1 month. In 29 eyes (91%), the results obtained remained stable during a 1-year follow-up; in two eyes (6%), the 1-month results worsened by more than 1.00 D and in one eye (3%), results improved by more than 1.00 D. There were no complications during or after surgery. Wound gaping resulting in epithelial plugs did not occur. No patient lost one or more lines of spectacle-corrected visual acuity, but 13 eyes (40%) gained one or more lines.

CONCLUSION

The technique of correcting corneal astigmatism by trephining to a depth of 300 microns, with deepening of the wound to 550 microns along the steep meridian and using no sutures can correct up to 10.00 D of astigmatism with reasonable stability.

Correcting postoperative astigmatism using curved lamellating keratotomy

PURPOSE

To ascertain whether the change in refraction caused by paired lamellating corneal incisions in cadaver eyes could be achieved in living eyes and whether wound healing influences this effect.

SETTING

Virchow Hospital Eye Clinic, Humboldt University, Berlin, Germany.

METHODS

This prospective study included 45 patients who had a follow-up of 15 months. All had astigmatism of at least 2.00 diopters (D) induced by previous cataract surgery. Optical zones of 7.0 and 8.0 mm and chordal lengths of 3.0 and 5.0 mm were used. All incisions were paired.

RESULTS

Mean preoperative astigmatism measured with a keratometer was 3.64 D +/- 0.89 (SD). After 15 months, it was 1.00 +/- 0.76 D, and mean induced astigmatism was 3.18 +/- 1.30 D. The 7.0 mm group had a mean induced astigmatism of 3.93 +/- 1.52 D, which was significantly higher than that in the 8.0 mm group (mean 2.60 +/- 0.74 D) at a uniform chordal length of 3.0 mm. Mean uncorrected visual acuity was 0.26 +/- 0.14 preoperatively and 0.50 +/- 0.28 after 15 months; mean corrected visual acuity improved from 0.58 +/- 0.21 to 0.76 +/- 0.21. Mean endothelial cell count was 1799 +/- 595 cells/mm2 preoperatively and 1784 +/- 589 cells/mm2 after 6 months; the difference was not significant.

CONCLUSION

Curved lamellating keratotomy gives stable postoperative refractive results without significantly affecting endothelial cell count or visual acuity.

Clinical results of arcuate incisions to correct astigmatism

PURPOSE

To evaluate the effectiveness of arcuate incisions for correcting congenital, post-cataract, post-radial keratotomy, and post-trapezoidal keratotomy astigmatism.

SETTING

Buzard Eye Institute, Las Vegas, Nevada.

METHODS

In this retrospective study, 46 eyes of 29 patients had arcuate incisions to correct astigmatism. The average age of patients was 52 years.

RESULTS

Mean preoperative astigmatism was 3.51 +/- 1.57 D (keratometric) and 3.41 +/- 1.44 D (manifest). Mean preoperative uncorrected visual acuity was 20/80, ranging from 20/30 to 20/400. Thirty eyes had a pair of 45-degree arcuate incisions, 10 eyes had a pair of 60-degree arcuate incisions, and 6 eyes had a pair of 90-degree arcuate incisions. Mean follow-up was 6 months. Mean postoperative astigmatism was 1.46 +/- 1.07 D (keratometric) and 1.05 +/- 0.94 D (manifest), with a reduction of astigmatism in all operated eyes. Mean postoperative uncorrected visual acuity was 20/32, ranging from 20/20 to 20/60. The analysis of the vector astigmatic change showed that only two patients were overcorrected after the procedure.

CONCLUSION

The predictability and safety of arcuate incisions are reflected in these results.

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

BACKGROUND

High astigmatism can be corrected using trapezoidal or arcuate transverse keratotomies. Videokeratography enables qualitative evaluation of the corneal topography.

METHODS

Fifty-five eyes of 41 patients presenting with high astigmatism after penetrating keratoplasty or naturally occurring astigmatism (mean, 6.29 diopters [D]; range, 3.00 to 16.00 D) underwent correction using either intersecting trapezoidal or arcuate transverse keratotomies. Corneal topographic maps were analyzed and classified into keratographic patterns. Mean follow up was 3 years (range, 1 to 6 years).

RESULTS

The mean net decrease in refractive astigmatism was 3.60 D (52.7% reduction). The flattening/steepening ratio was on average higher for intersecting trapezoidal keratotomy (7.26 for astigmatism after penetrating keratoplasty and 8.31 for naturally occurring astigmatism) than for arcuate transverse keratotomy (.98 in astigmatism after penetrating keratoplasty and 1.76 in naturally occurring astigmatism). Accordingly, intersecting trapezoidal keratotomy tended to produce a hyperopic shift in the spherical equivalent refraction (mean hyperopic shift, 2.65 and .56 D, respectively). The mean vector-corrected change of refractive astigmatism after intersecting trapezoidal keratotomy was 88.8% in naturally occurring (n = 21 eyes) and 70.3% in penetrating keratoplasty astigmatism (n = 13). Arcuate transverse incisions corrected on average 79.9% of naturally occurring (n = 13) and 60.8% of penetrating keratoplasty astigmatism (n = 8). Videokeratography showed the asymmetric bowtie pattern as the most frequent pattern for both procedures. Intersecting trapezoidal keratotomy was characterized by relatively higher incidences of polygonal and irregular patterns. Arcuate transverse incisions caused less wound healing defects and glare than intersecting trapezoidal keratotomy.

CONCLUSIONS

Both intersecting trapezoidal keratotomy and arcuate transverse incisions effectively reduced high naturally occurring astigmatism and astigmatism after penetrating keratoplasty. However, greater corneal surface irregularity and more complications were seen following intersecting trapezoidal keratotomy. Trapezoidal keratotomy should not be used unless a large decrease of myopia is needed, and then a nonintersecting technique is preferable.

Transverse incisions for mixed and myopic idiopathic astigmatism

PURPOSE

To determine the efficacy and safety of the Casebeer transverse nomogram for correcting idiopathic astigmatism using transverse incisions (T-incisions) with variable optical zones.

SETTING

Rancho Bernardo Eye Center, San Diego, California.

METHODS

This retrospective study comprised 173 eyes of 100 consecutive patients who had T-incisions according to the Casebeer transverse nomogram to correct mixed or myopic astigmatism. Preoperative cylinder ranged from 0.75 to 6.00 diopters (D). The nomogram was modified for eyes with preoperative cylinder from 1.75 to 6.00 D. Principal outcome measures were net residual astigmatism for all eyes and uncorrected visual acuity in eyes with the highest preoperative cylinder (3.25 to 6.00 D).

RESULTS

A comparison of preoperative astigmatism (mean 3.07 D +/- 1.53 [SD]) and net residual astigmatism showed significant reduction in all diopter categories. Enhancements were done in 16.2% of eyes, mostly those with high preoperative cylinder. Patient age did not seem to affect results. No patient, including those with smaller optical zones, lost two or more Snellen lines of best corrected visual acuity.

CONCLUSION

Use of the Casebeer transverse nomogram with T-incisions and variable optical zones effectively and safely reduced most idiopathic astigmatism between 0.75 and 5.50 D. Modifications to the nomogram yielded similar results in eyes with a higher preoperative cylinder.

Transverse keratotomy to correct high corneal astigmatism after cataract surgery

PURPOSE

To assess the outcome of transverse keratotomy to correct high corneal astigmatism after cataract surgery.

SETTING

Vall d'Hebron Hospital, Department of Ophthalmology, Cornea and Refractive Surgery Unit, Barcelona Autónoma University, Spain.

METHODS

Thirty-two eyes with regular corneal astigmatism between 2.50 and 5.00 diopters (D) after previous cataract surgery had two transverse incisions with an optical zone of 5.0 or 7.0 mm, a depth of 80 or 90%, and a length of 3.0 or 4.0 mm, depending on the amount of astigmatism and based on a personal nomogram we developed.

RESULTS

From 80 to 100% of the desired correction was achieved in 38.7% of eyes and from 60 to 80% in 38.9%. At 6 months, only 9.1% had a keratometric change of more than 0.50 D. Best corrected visual acuity was the same or better in 85.2% of patients; no patient lost more than one Snellen line.

CONCLUSION

This easy, safe technique had low anatomical and refractive morbidity and high efficacy, making it an excellent option for eyes with high astigmatism after cataract surgery. More research is required in view of the considerable unpredictability of our results and the disparity in methods and results of other published studies.

Analysis of astigmatic keratotomy with a 5.0-mm optical clear zone

PURPOSE

To investigate the surgically induced refractive change after astigmatic keratotomy with a 5.0-mm optical clear zone in patients with severe naturally occurring astigmatism.

METHODS

We analyzed surgically induced refractive change in 40 consecutive eyes undergoing astigmatic keratotomy with a 5.0-mm optical clear zone. The surgically induced refractive change was calculated according to the method of Holladay, Cravy, and Koch with some modifications. Eyes were divided into two groups: Group I included eyes with mixed astigmatism and a maximum preoperative spherical equivalent of +1.25 diopters that underwent arcuate keratotomy, and Group II included eyes with compound myopic or simple myopic astigmatism (maximum preoperative spherical equivalent of -3.00 diopters) or mixed astigmatism with low minus spherical equivalent that underwent four-incision radial keratotomy and arcuate keratotomy.

RESULTS

After refractive surgery, all eyes experienced a reduction of astigmatism when examined three months or more after surgery. Only one eye from each group was overcorrected. The magnitude of refractive astigmatism of surgically induced refractive change was 3.25 +/- 0.90 diopters for eyes in Group I and 3.25 +/- 0.80 diopters for eyes in Group II. There was minimal axis deviation. Eyes in Group I had more flattening with the wound than steepening against the wound, with a coupling ratio of -0.86 +/- 0.36, whereas in Group II, there was flattening both with the wound and against the wound. The net effect of surgery (sum of the primary and secondary effects) was more flattening than steepening in Group I eyes, and flattening of the circumference of the eye in Group II. A decrease of one line of best-corrected visual acuity was observed in one (6.6%) of 15 eyes in Group I and in two (8%) of 25 eyes in Group II.

CONCLUSIONS

A 5.0-mm optical clear zone arcuate keratotomy is an effective method for correcting moderate to severe naturally occurring astigmatism. Further investigation of this optical clear zone size on glare and contrast sensitivity testing is necessary and is underway.

Photoastigmatic refractive keratectomy in 168 eyes: six-month results

Using a 193 nm excimer laser, we performed elliptical astigmatic and spherical corneal ablation on 168 eyes with compound myopic astigmatism and analyzed the three- and six-month postoperative results. Mean preoperative astigmatism was 1.51 +/- 0.81 diopters (D). Mean three- and six-month postoperative astigmatism was 0.70 +/- 0.58 D and 0.67 +/- 0.60 D, respectively. Six months after surgery, eyes with less than 1.00 D preoperative astigmatism improved 4.8%. The improvement was 53.5% and 59.1% for eyes with a preoperative astigmatism of 1.00 D to 2.00 D and above 3.00 D, respectively. Overall, astigmatism improved 55.6%. There was a wide distribution from overcorrection to undercorrection. Astigmatism six months after surgery was within 10 degrees of the preoperative axis in 46.1% of eyes.

Transverse astigmatic keratotomy combined with phacoemulsification and intraocular lens implantation

Transverse astigmatic keratotomy is a surgical technique to correct preoperative corneal astigmatism during cataract surgery. The operative technique is described and the results of my first 40 cases are reviewed. The average keratometric astigmatism for this group before surgery was 2.6 dipoters (D). The average reduction in astigmatism was 1.5 D, which yielded a final residual average astigmatism of 1.1 D after surgery. Cases of substantial astigmatism showed the most improvement. Less improvement was seen in cases of minimal preoperative astigmatism. No increase in net keratometric astigmatism was seen in any of the eyes studied. Minor complications were limited to several small corneal abrasions created by the front-cutting diamond blade and one late temporary wound dehiscence. The only serious complication was one case of corneal macroperforation. Recommendations for handling this complication and future high astigmatism cases are given.