Analysis of Changes in Anterior, Posterior and Total Corneal Astigmatism after On-Axis Cataract Surgery

PURPOSE: To assess the changes in anterior, posterior, and total corneal astigmatism after cataract surgery with on-axis clear corneal incision cataract surgery. METHODS: This study included 48 eyes (24 eyes with 'with-the-rule [WTR]' and 24 eyes with 'against-the-rule [ATR]') that underwent phacoemulsification and intraocular lens insertion through on-axis clear corneal incision. The ATR group with vertically steep axis of posterior corneal astigmatism was divided into subgroups 1 and 2 for the opposite axis. Autorefraction, uncorrected and best-corrected visual acuities were measured. Corneal astigmatism (anterior, posterior and total) was measured using Pentacam(R) preoperatively and 1 week, 1 month, and 2 months postoperatively. RESULTS: Multivariate linear regression analysis of preoperative data showed positive correlations among anterior, posterior and total astigmatism. Anterior corneal astigmatism showed a significant decrease in both WTR and ATR groups in all measured points (all p 0.05) and significant decrease in the ATR subgroup 1 (p 0.05). According to correlation analysis based on trend line equations, 1.7 diopters of anterior astigmatism could expect 0.3 diopters of posterior astigmatism and 0.5 diopters of total astigmatism for the WTR group and 0.4 diopters of anterior astigmatism could expect 0.2 diopters of posterior astigmatism and 0.4 diopters of total astigmatism for the ATR group. CONCLUSIONS: Considering the majority of cataract patients have vertically steep posterior corneal astigmatism, temporal incision for ATR patients is generally effective. Moreover, for patients with WTR astigmatism of more than 1.7 diopters or ATR astigmatism greater than 0.8 diopters, additional preoperative correction based on posterior astigmatism is needed for more precise prediction of postoperative total corneal astigmatism.

Comparative study of surgically induced astigmatism in superior versus temporal incision in small incision cataract surgery cases.

Background: Location of incision has a significant impact on surgical outcome. It has been reported that temporal incisions induce less astigmatism than superior incisions indicating the importance of incision location. The objective of the present study was to study the effect of surgical induced astigmatism in superior versus temporal incision in small incision cataract surgery cases. Methods: 100 patients of cataract attending to Sarojini Devi eye hospital with the rule and against the rule astigmatism were included in the study. The astigmatic profile and the effect of surgical incision on astigmatism were studied. A prospective study was done in which patients were divided into two groups. MSICS was performed with superiorly located incision in group I and temporally located incision in group II. Results: Out of the total 100 patients undergoing MSICS, 59 patients had ATR, 36 patients had WTR and 5 patients had no astigmatism. Thus the pre-operative astigmatic profile shows that ATR is more common type of astigmatism in this group. Among 50 patients in superior incision group, 18 had pre-operative WTR, 29 had ATR and 3 did not have astigmatism. Postoperatively the no. of patients with WTR decreased to 10, the no. of patients with ATR increased to 35 showing that superior incision flattens vertical meridian and steepens the horizontal meridian causing ATR shift. Among 50 patients in temporal incision group, 18 had pre-operative WTR, 30 had ATR and 2 did not have astigmatism. Post operatively the no of patients with WTR increased to 25, the no of patients with ATR decreased to 20. Conclusions: Placement of incision on steep axis reduces pre-existing astigmatism. Thus in ATR astigmatism it is placed temporally and in WTR astigmatism it is placed superiorly. Thus a simple modification in incision placement can minimize surgically induced astigmatism and reduce pre-existing astigmatism.

Comparison of Higher Order Aberrations and Astigmatism after On-Axis Small Incision Cataract Surgery

PURPOSE: To assess the changes of corneal astigmatism and higher order aberrations (HOAs) of the anterior and posterior corneal surface after cataract surgery with on-axis clear corneal incision in eyes with-the-rule (WTR) astigmatism and against-the-rule (ATR) astigmatism. METHODS: This study included 50 patients who underwent phacoemulsification and IOL insertion through a 2.8-mm on-axis clear corneal incision. The eyes were divided into two groups: (1) 26 eyes with WTR astigmatism with a superior incision and (2) 24 eyes with ATR astigmatism with a temporal incision. During the follow-up period, visual acuity was measured, and the surgically induced astigmatism (SIA) and HOAs of the anterior and posterior corneal surface were measured with Pentacam(R) (Occlus, Wetzlar, Germany) preoperatively and 1 week, 1 month, and 2 months postoperatively. RESULTS: There were no significant differences in UCVA and BCVA between the two groups. HOAs increased in both groups 1 week after surgery, but no significant differences were found between the groups (p > 0.05). Surgically induced astigmatism was larger in the WTR group than in the ATR group (p < 0.05). At postoperative 2 months, there were significant differences in HOAs between the two groups, and there were statistically significant differences in HOAs, oblique trefoil at front side, and in HOAs, horizontal coma at rear side (p < 0.05). CONCLUSIONS: In conclusion, superior incision in eyes with WTR astigmatism resulted in higher SIA compared to temporal incision in eyes with ATR astigmatism. Moreover, HOAs was significantly decreased in eyes with WTR astigmatism with superior incision. Thus, superior incision could be more effective in reducing corneal astigmatism in eyes with WTR astigmatism.

Distribution and Change of Total Astigmatism, Corneal Astigmatism and Residual Astigmatism with Age in Patient with Emmetropia

PURPOSE: We evaluated the distribution and change of total, corneal and residual astigmatism with age in patients with emmetropia. METHODS: We examined the visual acuity, refraction, and corneal curvature in 263 persons aged from 3 to 83 years (mean, 38 years), with a spherical equivalent refraction of under +/-0.75 diopter (D). We analysed the distribution and change of the astigmatism. RESULTS: Total astigmatism was changed from with-the-rule (WTR) to against-the-rule (ATR) with aging based on WTR of 0.31 +/- 0.48 D in the 3-10 year-old group, ATR of 0.02 +/-0.52 D in the 31-40 year-old group and ATR of 0.65 +/- 0.66 D in the 71-83 year-old group. Corneal astigmatism showed a similar pattern to that of total astigmatism with WTR of 1.03 +/- 0.47 D, WTR of 0.37 +/- 0.78 D, ATR of 0.05 +/- 0.59 D and ATR of 0.31 +/- 0.64 D in the 3-10, 31-40, 61-70 and 71-83 year-old groups, respectively. Residual astigmatism showed ATR astigmatism in all age groups such as ATR of 0.71 +/- 0.48 D, ATR of 0.60 +/- 0.44 D and ATR of 0.35 +/- 0.71 D in the 3-10, 41-50 and 71-83 year-old groups, respectively. CONCLUSIONS: Total and corneal astigmatism showed the change from WTR to ATR, and residual astigmatism showed the pattern of decreasing ATR with aging in patients with emmetropia. The change of total astigmatism with aging seems to be influenced by that of corneal astigmatism rather than by that of residual astigmatism.

Pseudophakic Residual Astigmatism

We investigated pseudophakic residual astigmatism in order to minimize postoperative refractive astigmatism. We examined 110 eyes of 87 patients who had undergone phacoemulsification with small incision and posterior chamber intraocular lens (IOL) implantation. Corneal astigmatism was measured using an autokeratometer (RK-5, canon), refractive astigmatism by manifest refraction, and residual astigmatism by vector analysis. Mean pseudophakic residual astigmatism was +0.47 X 176degrees, predominantly against-the-rule. Variations of pseudophakic residual astigmatism according to sex, age and IOL type were not statistically significant. When performing cataract surgery as refractive surgery, we may consider that pseudophakic residual astigmatism is approximately 0.50D against-the-rule.

Change of Corneal Astigmatism with Aging in Koreans with Normal Visual Acuity

PURPOSE: To evaluate the distribution and change of corneal astigmatism with aging in persons with normal visual acuity. METHODS: We classified 504 subjects (504 eyes) showing good naked vision at least 1.0 from 3 to 83 years into 15 groups with 5 year interval and analyzed corneal astigmatism using refraction and keratometry. RESULTS: With-the-rule astigmatism (WTR) was shown in 98.5% between 3 and 25 years and progressively decreased with aging. In 61 to 65 years' group WTR was 34.1% and against-the-rule astigmatism (ATR) was 36.4%. After then ATR was more predominant. Mean corneal astigmatism was about 1 diopter under 20 years and progressively decreased to 0.5 D at 60 years with aging. CONCLUSIONS: 84.7% of persons with normal visual acuity have corneal astigmatism. WTR was predominant in the youth but progressively decreased with aging to equal balance with ATR in the mid sixties. After then corneal astigmatism would be inclined to against-the-rule. The amount of corneal astigmatism was decreased from about an 1 diopter in twenties to 0.5 diopter in sixties.

Induced Astigmatism after Rabbit Cataract Surgery Using Tissue Adhesive

In order to compare the amount of surgically induced astigmatism among sutureless group(Group 1),10-0 nylone suture group(Group 2),and using tissue adhesive group(Group 3),we analysed a series of rabbit cataract surgery cases in these three groups. We performed cataract surgery on 30 eyes of 15 rabbits by Irrigation and aspiration technique. After cataract surgery,10 eyes by sutureless technique,10 eyes were closed by conventional 10-0 nylon suture technique, and 10 eyes by tissue adhesive(Beriplast) technique.We collected keratometric data before and after surgery(At 1,2,4,8 weeks).In postoperative astigmatic change,three groups had the distinct features in the evolution for postoperative astigmatism.The group 1 showed early against-the-rule(ATR)astigmatism,which advanced ATR and showed about 0.5D astigmatic change at 8 weeks.The group 2 showed early with-the-rule(WTR)astigmatism about 1.13D,which advanced toward ATR from 1week.The group 3 showed little ATR about 0.2D,which was minimal change in astigmatism.At 8 weeks after operation,there was no signifi-cant difference in the astigmatic change among the three groups(P>0.05), which were no complications observed. In this study,the tissue adhesive(Beriplast)seem to be a simple,effective and less induced astigmatic changing corneoscleral suture technique than other suture techniques

The Location of Scleral Incision for Decrease of corneal Astigmatism in Sutureless Cataract Surgery

We analysed postoperative corneal astigmatic changes to know that preoperative astigmatism was able to decreased according to the location of incision in sutureless cataract surgeries. We divided 70 patients, 81 eyes that scleral pocket incision, phacoemulsification, and posterior chamber intraocular lens implantation was performed into two groups. The one is the preoperative with-the-rule(WTR)astigmatism more than 1 diopter(D) with superior incision, and the other is the preoperative WTR less than 1D or against-the-rule (ATR) astigmatism with temporal incision. We followed up the corneal astigmatic chnges until six months postoperatively. According to the results of algebraic analysis, in the superior incision group, postoperative astigmatic changes showed WTR decrease of 0.43D immediately, which advanced toward ATR decrease of 0.41D immediately, which keep up ATR decrease and showed ATR decrease of 0.44D at 6 months. According to the results of vector analysis, surgical inducced corneal astigmatism was o.69D in superior incision group and 0.50D in temporal incision group at postoperative 1day. It was 0.98D in superior incision group and 0.57D in temporal incision group at postoperative 6 months. We could decrease preoperative corneal astigmatism with performing incision at the position of greater corneal curvature. Temporal incision group showed less surgical induced astigamatic changes than superior incision.

Short-term Effect of Suture Tension after Scleral Tunnel Incision in Posterior Chamber Lens Implantation on Preexisting Astigmatism

In this two-month prospective study, reduction of preexisting astigmatism in 35 eyes was attempted by tension control of a mattress. In the first group, which had WTR astigmatism over 1.5 diopter(D) the wound was closed with loose mattress suture(MS). This reduced WTR astigmatism 1.52 D at 2 months. In the second group(WTR astigmatism, under 1.5 D)closed with a adaptation suture, the preexisting WTR astigmatism did not show a significant shift toward ATR astigmatism. In the third group closed with a tight MS, the preexisting ATR astigmatism was not significantly increased.

Cataract Surgery Using a Sleral Pocket Incision of 7 mm in Length

During a eight-month period from june 1993, cataract surgery using a scleral pocket of 7 mm in length was performed on 30 eyes of 26 patients. In order to evaluate the effect of chamber entry length and closure technique on astigmatic changes and visual recovary, three different surgical procedures were carried out and compared retrospectively. The visual acuity, refraction and keratometry were assessed at every week. The H group(15 eyes) had a single horizontal suture after phacoemulsification followed by implantation of a one piece of PMMA lens through 7 mm chamber entry. The F group(6 eyes) had a single horizontal suture followed by implantation of a foldable lens through 4 mm chamber entry. The R group(9 eyes) had a single radial suture followed by implantation of one piece of PMMA lens through 7 mm chamber entry. Overall uncorrected visual acuity of 20/40 or better was 67% at 1 week, 93% at 8 weeks postoperatively and there was no statistically significant difference among the three groups(p>0.05). The overall change of mean refractive astigmatism from 1 to 8 weeks postoperatively was 0.69D and there was no statistically significant difference among the three groups(p>0.05). The overall change of mean keratometric astigmatism method from 1 to 8 weeks postoperatively was 0.12D and there was no statistically significant difference among the three groups(p>0.05). Early clinical observations indicate that cataract surgery using a scleral pocket of 7 mm in length shows early visual recovery and minimizes surgically induced astigmatism without serious complications.

Corneal Astigmatism after Cataract Surgery: The Effect of Electrocautery

Corneal astigmatism after cataract surgery: The effect of electrocautery. We analized the effect of electrocautery on corneal astigmatism after cataract operation. Phacoemulsification and PCL implantation were performed by standard technique with 5.5 mm scleral pocket incision and sutureless method. In electrocautery group. scleral cautery was done at the site of scleral pocket incision and in no electrocautery group, cautery was not performed. 53 eyes(electrocautery group) showed slight against the rule change(-0.26D +/- 0.72) of corneal astigmatism, while 24 eyes(no electrocautery group) showed slight with the rule change(+0.36D +/- 0.67) of corneal astigmatism at post-operative 2 months. And these difference was statistically significant.(Student's t-test; p=0.019) Therefore, we found the scleral electrocautery at the incision site during cataract surgery induced slight against the rule change of corneal astigmatism.

The Effect of Astigmatic Control after Cataract Extraction with Temporal Incision

A group of 25 preoperative against-the-rule(AR) eyes had undergone phacoemulsification and posterior chamber lens implantation, 15 of them prepared with lateral(temporal) scleral pocket incision and 10 with superior scleral incision. Temporal incision group showed early AR astigmatism increment by about 1 diopter(D), which decayed slowly over the next 2 months. Superior incision group showed early with-the-rule (WR) astigmatism by about 2.5D, which shifted toward AR astigmatism at postoperative 10 day and the AR astigmatism increased substantially by the next 2 months. The early postoperative complications were hyphema(2 eyes, 13.3%) and corneal edema(1 eye, 6.7%) in the temporal incision group, which cleared spontaneously within 1 week pctoperative. There were no hyphema and corneal edema in the superior incision group. In summary, the temporal incision effectively achived rapid post-operative astigmatic recovery with strong axial stability in a manner that surgically induced astigmatism favorably reduces pre-existing AR astigmatism.