Transverse astigmatic keratotomy combined with phacoemulsification and intraocular lens implantation

Three Methods for Correction of Astigmatism during Phacoemulsification

PURPOSE

To compare the safety and efficacy of three methods for correcting pre-existing astigmatism during phacoemulsification.

METHODS

This prospective, comparative, non-randomized study was conducted from March 2010 to January 2011, and included patients with keratometric astigmatism ≥1.25 D undergoing cataract surgery. Astigmatism was corrected using the following approaches: limbal relaxing incisions (LRI) on the steep meridian, extension and suturing of the phaco incision created at the steep meridian (extended-on-axis incision, EOAI), and toric intraocular lens (tIOL) implantation. Keratometric and refractive astigmatism were evaluated 1, 8, and 24 weeks postoperatively.

RESULTS

Eighty-three eyes of 72 patients (35 male and 37 female) with mean age of 62.4 ± 14.3 (range, 41-86) years were enrolled. The astigmatism was corrected by using the LRI, EOAI and tIOL implantation methods in 17, 33 and 33 eyes, respectively. Postoperative uncorrected distance visual acuity (UDVA) was significantly improved in all three groups. The difference in postoperative UDVA was not statistically significant among the study groups throughout follow-up except at week 24, when UCVA was significantly better in the tIOL group as compared to the EOAI group (P = 0.024). There is no statistically significant difference of correction index and index of success between three groups at week 24 (P = 0.085 and P = 0.085 respectively).

CONCLUSION

There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon.

Peripheral corneal relaxing incisions combined with cataract surgery

PURPOSE

To analyze the effectiveness of peripheral corneal relaxing incisions (PCRIs) in correcting corneal astigmatism during cataract surgery.

SETTING

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.

METHODS

In 115 eyes of 94 patients (mean age 69 years +/- 12 [SD]), cataract surgery was combined with PCRIs. The PCRIs were created according to a nomogram based on age and preoperative keratometric astigmatism. Postoperative keratometric astigmatism was measured at 1 day and 1 and 4 months. Vector analyses using the Holladay-Cravy-Koch formula and Alpins method were performed.

RESULTS

The PCRIs significantly decreased keratometric astigmatism in patients with preexisting with-the rule (WTR) or against-the-rule (ATR) astigmatism and increased the percentage of the eyes with lower keratometric astigmatism in each group. Four months postoperatively in patients with WTR astigmatism, single and paired 6.0 mm PCRIs induced mean with-the-wound minus against-the-wound changes (WTW-ATW) of -0.55 diopter (D) and -1.18 D, respectively. In eyes with ATR astigmatism, the mean WTW-ATW changes induced by single 4.5 mm, single 6.0 mm, and paired 6.0 mm PCRIs were -2.18 D, -2.02 D, and -2.72 D, respectively. These mean WTW-ATW changes did not significantly regress from 1 day to 4 months postoperatively.

CONCLUSIONS

Peripheral corneal relaxing incisions were effective in reducing preexisting astigmatism during cataract surgery. A modified nomogram is proposed. The long-term effect of PCRIs should be evaluated.

Intraoperative Arcuate Transverse Keratotomy With Phacoemulsification

PURPOSE

To evaluate the efficacy of paired intraoperative arcuate transverse keratotomy at a 7-mm-diameter zone along with a 3.5-mm clear corneal phaco tunnel in the steeper axis to correct pre-existing astigmatism.

METHODS

A prospective randomized case-control study was conducted on 34 eyes of 28 patients with immature senile cataract. They were divided into two groups; in one group (17 eyes) intraoperative arcuate keratotomy was coupled with phacoemulsification in the steeper meridian (arcuate keratotomy group; mean preoperative astigmatism 2.28 +/- 0.89 D) and the other group (17 eyes) phacoemulsification was performed in the steeper meridian without arcuate keratotomy (control group; mean preoperative astigmatism 2.04 +/- 0.50 D). The patients were examined at 1 day, and 1, 4, and 8 weeks postoperatively. Correction of keratometric astigmatism, surgically induced refractive changes, magnitude and axis of cylinder, spherical equivalent refraction, with and against the wound change, and coupling ratio were evaluated.

RESULTS

Mean reduction in keratometric astigmatism in the keratotomy group was 1.26 +/- 0.54 D (P = .0067) and in the control group was 0.48 +/- 0.60 D (P = .0423). The difference in reduction of keratometric astigmatism between the two groups was statistically significant (P = .0296). Surgically induced refractive change at 8 weeks follow-up was 2.15 +/- 1.13 D in the keratotomy group and 1.50 +/- 1.32 D in the control group (P = .046). Coupling ratio was -1.10 +/- 0.43 in the keratotomy group at 8 weeks after surgery while the control group was -0.82 +/- 0.38.

CONCLUSION

A combination of intraoperative arcuate keratotomy with steep axis phacoemulsification incision is more effective than steep axis phacoemulsification incision alone in reducing pre-existing astigmatism.

Paracentral photoablations to correct higher grades of naturally occurring astigmatism

PURPOSE

To evaluate the efficacy of paracentral ablations in treating higher degrees of naturally occurring myopic and hyperopic astigmatism.

SETTING

Augenklinik, Kreiskrankenhaus Bad Hersfeld, Germany.

METHODS

Twenty-five eyes (7 with hyperopia, 18 with myopia) with naturally occurring corneal astigmatism greater than 1.75 diopters (D) were treated by excimer laser. The mean refractive cylinder was -4.05 D +/- 1.46 (SD) (range -1.75 to -7.00 D). The intention was to reduce the astigmatism without consideration of the spherical refractive error. Two paracentral ablations were performed by photorefractive keratectomy with treatment zones of 3.5 mm in the flatter meridian of the cornea. Objective refraction, best corrected visual acuity (BCVA), changes in corneal radius, development of haze, and regression were recorded.

RESULTS

The paracentral ablations induced a steepening of the corneal radius in the flatter meridian from 8.12 mm (mean preoperative value) to 7. 84 mm (mean postoperative value) and thus reduced the mean refractive cylinder to -1.12 +/- 0.82 D (range 0.00 to - 3.00 D), corresponding to a mean reduction of 78%. No eye experienced a loss of Snellen lines. The preoperative BCVA (mean 20/25; range 20/50 to 20/20) was unchanged postoperatively

CONCLUSIONS

Paracentral ablations resulted in a stable corneal curvature immediately after epithelial healing, with a moderate regression over time. Paracentral ablations with the excimer laser appear to be a safe and effective method to correct higher grades of corneal astigmatism.

Clear corneal cataract surgery and the correction of myopia, hyperopia, and astigmatism

PURPOSE

Advances in cataract removal using topical anesthesia through a clear corneal microincision have created a new opportunity to fully correct refractive errors at the time of cataract surgery. This study was undertaken to assess the effectiveness of keratolenticuloplasty (KLP), the simultaneous modification of the cornea at cataract removal to create emmetropia with lens implantation.

METHODS

Data were analyzed for 690 consecutive cataract procedures performed between March 1993 and March 1995, with follow-up of 12 to 24 months. Each patient underwent cataract removal with topical anesthesia, clear corneal incision fashioned as an arcuate keratotomy to correct pre-existing astigmatism, intercapsular phacoemulsification, and microinjection of a single-piece elastic intraocular lens (IOL) into the capsular bag to correct spherical error.

RESULTS

Preoperative best-corrected visual acuity was worse than 20/50 in all patients; 58% were myopic, 32% were hyperopic, and 57% had astigmatism of greater than 1 diopter (D). Postoperatively, spectacle independence was achieved with uncorrected visual acuity of 20/40 or better in 87% of eyes. The sphere was fully corrected in 78%, within 1 D in 17%, and within 2 D in 5%. No patients were overcorrected. The cylinder was fully corrected in 72%, within 1 D in 26%, and within 2 D in 2%. Of those with residual astigmatism, there was no significant postoperative shift in cylinder axis. There were no sight-threatening complications. All patients were able to resume normal unrestricted activities within 24 hours of undergoing the procedure.

CONCLUSIONS

The KLP technique can correct spherical and astigmatic refractive errors, helping individuals become free of eyeglasses after clear corneal cataract surgery.

Astigmatic keratotomy combined with myopic keratomileusis in situ for compound myopic astigmatism

PURPOSE

Myopic keratomileusis in situ by an automated microkeratome corrects myopia but not astigmatism, which is traditionally corrected by astigmatic keratotomy months after keratomileusis. We developed a technique for simultaneously correcting astigmatism and severe myopia, and examined its effectiveness in a retrospective case-control study.

METHODS

Thirty-four eyes (23 patients) underwent myopic keratomileusis in situ combined with one or two arcuate keratotomy incisions performed after the refractive cut, in the bed of the primary keratectomy flap. The myopic keratomileusis control group consisted of 34 matched eyes (30 patients) undergoing keratomileusis without astigmatic keratotomy. The astigmatic control group consisted of 117 unmatched eyes (85 patients) undergoing astigmatic keratotomy combined with radial keratotomy.

RESULTS

Mean refractive astigmatism in the study group decreased from 2.4 diopters (range, 1.0 to 4.0 diopters) preoperatively to 1.7 diopters (range, 1.0 to 4.0 diopters) at three months postoperatively, and increased by 0.4 diopter in the myopic keratomileusis control group at three months postoperatively (P < .005). Eighteen of 27 eyes in the study group showed decreased refractive astigmatism compared with ten of 34 eyes in the myopic keratomileusis control group (P < .0001). Combining astigmatic keratotomy with myopic keratomileusis produced 0.2 +/- 0.9 diopter less astigmatic correction than that expected from the astigmatic control group. One of 27 eyes lost two or more lines of best spectacle-corrected visual acuity at the three-month postoperative visit. No eye lost two or more lines of best spectacle-corrected visual acuity at postoperative month 6.

CONCLUSION

Eyes with substantial preoperative refractive astigmatism that undergo myopic keratomileusis in situ may benefit from simultaneous astigmatic keratotomy to reduce residual post-operative refractive astigmatism.

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.

Toric intraocular lenses: correcting astigmatism while controlling axis shift

We evaluated the efficacy of toric intraocular lenses (IOLs) implanted in the eyes of 47 patients who had preoperative against-the -rule astigmatism. The lenses, which had a cylinder power of 2.00 diopters (D) (n = 26) or 3.00 D (n = 21), were implanted through a 5.7 mm incision after cataract extraction by phacoemulsification. Best corrected visual acuity three months postoperatively was 20/25 or better in 77% of eyes. The 3.00 D IOLs resulted in better correction than the 2.00 D IOLs when the axis shift of the lens was less than 30 degrees. A negative effect occurred in some eyes in which the lens axis rotated more than 30 degrees. The maximum acceptable axis shift seems to be less than 30 degrees.

Reduction of corneal astigmatism at cataract surgery

We studied the effect at three months of four transverse astigmatic keratotomy incisions (TAK) performed prior to phacoemulsification in 61 eyes on corneal astigmatism. The optical zone was varied in each case depending upon the magnitude of preoperative astigmatism. The eyes were compared to 105 control eyes in which no astigmatic incisions were performed to assess the estimated effect of the TAK incisions. Keratometry readings were taken preoperatively and three months postoperatively. Surgically induced astigmatism was measured using vector corrected astigmatism. Improvement in astigmatism was reported in all three optical zone groups, but the astigmatism was undercorrected in each. No complications affecting vision were reported, indicating that TAK may be a safe way to reduce postoperative astigmatism when combined with phacoemulsification.