Surgically induced astigmatism assessment: comparison between three corneal measuring devices

Comparison of corneal surgically induced astigmatism calculations based on keratometry measurements made by 2 biometric devices

PURPOSE

To compare calculated corneal surgically induced astigmatism (SIA) by means of anterior-based keratometry (K) and total keratometry (TK) measurements made by 2 biometric devices.

SETTING

Ophthalmology Department, Shaare Zedek Medical Center, Jerusalem, Israel.

DESIGN

Retrospective, consecutive case series.

METHODS

The medical records of patients who had undergone cataract surgery through a 2.4 mm temporal clear corneal incision by a single surgeon between March 2018 and November 2020 were retrospectively reviewed. Patients for whom there were preoperative and postoperative K measurements assessed by 2 biometric devices, optical low-coherence reflectometry (OLCR) (Lenstar LS900, Haag-Streit, software v. eye suite i/9.1.0.0) and swept-source optical coherence tomography (SS-OCT) (IOLMaster700, Carl Zeiss Meditec AG, software v. 1.80.6.60340), were identified. Corneal SIA (mean vector value) was calculated by vector analysis for 3 groups: SS-OCT(K), SS-OCT(TK), and OLCR(K). Bivariate analyses were applied for comparisons.

RESULTS

147 eyes of 123 patients (73 right eyes and 74 left eyes) were enrolled in the study. The right eye corneal SIA values were 0.09 diopters (D) @ 136 degrees, 0.09 D @ 141 degrees, and 0.07 D @ 123 degrees for the SS-OCT(K), SS-OCT(TK), and OLCR, respectively. The corresponding left eye corneal SIA values were 0.13 D @ 120 degrees, 0.11 D @ 123 degrees, and 0.08 D @ 120 degrees. There were no statistically significant differences between the mean vector value and variance of the corneal SIA for the right (P = .78 and P = .65) and the left (P = .75 and P = .37) eyes of the 3 groups.

CONCLUSIONS

Corneal SIA values were low (0.07 to 0.13 D) and similar for the SS-OCT and the OLCR biometric devices with standard K measurements. TK measurements yielded similar corneal SIA values compared with anterior corneal-based measurements.

Comparison of surgically induced astigmatism between anterior and total cornea in 2.2 mm steep meridian incision cataract surgery

Background

This study aimed to compare surgically induced astigmatism (SIA) on the anterior and total cornea during cataract surgery through a 2.2 mm steep meridian incision.

Methods

The study included 69 left eyes of 69 patients who had undergone cataract surgery. The 69 eyes were classified into three subgroups according to the preoperative steep meridian. Following phacoemulsification, an intraocular lens was inserted into the bag. The keratometric measurements were taken 12 months postoperatively, on the anterior cornea (automated keratometer and anterior keratometry [K] from a rotating Scheimpflug camera) and total cornea (equivalent K reading [EKR] 3.0 mm, EKR 4.5 mm, total corneal refractive power (TCRP) 2.0 mm ring, TCRP 3.0 mm zone, TCRP 4.0 mm zone). The SIA was analyzed for each parameter.

Results

On the double-angle polar plot, the summated vector mean values of SIA determined by the automated keratometer and Scheimpflug anterior K were 0.28 diopter (axis: 177°) and 0.37 diopter (axis: 175°) in with-the-rule (WTR) astigmatism; 0.03 diopter (axis: 156°) and 0.18 diopter (axis: 177°) in oblique astigmatism; 0.15 diopter (axis: 96°) and 0.17 diopter (axis: 73°) in against-the-rule (ATR) astigmatism. The mean SIAs on the total cornea ranged from 0.31 to 0.42 diopter in WTR astigmatism; from 0.16 to 0.27 diopter in oblique astigmatism; from 0.04 to 0.11 diopter in ATR astigmatism. Mean magnitude SIA ranged from 0.41 to 0.46 diopter on anterior corneal surface and 0.50 to 0.62 diopter on total cornea. J₀ and J₄₅ of the posterior cornea showed no significant changes after cataract surgery, and the changes in J₀ and J₄₅ did not show any statistical differences between the anterior and total cornea (all p > 0.05).

Conclusions

There were no differences in the summed vector mean values of SIA between the anterior cornea and the total cornea.

Outcomes of 1.8-3.0 mm incision phacoemulsification combined with trabeculectomy for primary angle-closure glaucoma with cataract

AIM

To compare efficacy of coaxial microincisions (1.8 mm, 2.2 mm) and small incisions (3.0 mm) on phacoemulsification combined with trabeculectomy for primary angle-closure glaucoma (PACG) with cataract.

METHODS

Ninety-six patients (96 eyes) with PACG and cataract were recruited and randomly divided into three groups between January 2015 and June 2017. Group A (3.0 mm incision), B (2.2 mm incision), and C (1.8 mm incision) comprised 30, 34 and 32 eyes respectively. All cases were treated with clear corneal incision phacoemulsification combined with trabeculectomy. Data including best corrected visual acuity (BCVA), corneal astigmatism, corneal endothelial cell counts (CECC), intraocular pressure (IOP), and complications were collected before the operation, and at postoperative 1d, 1 and 3mo.

RESULTS

All the patients were successfully treated with surgery. The BCVA of groups B and C were significantly improved as compared to group A at postoperative 1d, 1 and 3mo (all P<0.05), but there was no difference between groups B and C at each time interval (all P>0.05). The corneal astigmatism of group A was statistically higher than that of group B (P=0.026); corneal astigmatism of group B was statistically higher than that of group C at postoperative 1d (P=0.006). The corneal astigmatism of group A at postoperative 3mo was significantly higher than that before operation (P=0.003). At postoperative 1 and 3mo, corneal astigmatism of groups B and C were significantly lower than that of group A (all P<0.05). The CECC in group B was significantly higher than that of group A (P=0.020), and CECC in group C was significantly higher than that of group B (P=0.034) at postoperative 1d. At postoperative 1 and 3mo, CECC of groups B and C were significantly higher than that of group A (all P<0.05). In each group, postoperative mean IOP at each time interval was significantly lower than preoperative IOP (all P<0.05).

CONCLUSION

Coaxial microincision phacoemulsification combined with trabeculectomy for PACG with cataract has better curative efficacy in reducing postoperative corneal astigmatism and corneal endothelial cell injury than traditional small incision combined surgery, and the 1.8 mm microincision has better curative efficacy than 2.2 mm microincision in the early postoperative period.

Comparative Analysis of One-Handed and Two-Handed Coaxial Phacoemulsification with 2.4-mm Clear Corneal Incision

PURPOSE

To compare the efficiency and safety of one-handed and two-handed coaxial phacoemulsification Material and Methods: Patients with cataracts underwent one-handed (one-handed group) or two-handed coaxial phacoemulsification (two-handed group) with a 2.4-mm clear corneal incision. Intraoperative phaco parameters, total surgical time, postoperative visual acuity, surgically induced astigmatism (SIA), corneal volume (CV), central corneal thickness (CCT) and corneal endothelial cell counts/size were compared between the two groups.

RESULTS

Each group comprised 105 eyes. There were no significant differences in the intraoperative phaco parameters and total surgical time between the two groups (all p > 0.05). Visual outcomes were significantly better in the one-handed group than in the two-handed group 1 week postoperatively (all p< 0.05) but not 1 month postoperatively. There was no significant difference in SIA between the two groups 1 week (p = 0.695) or 1 month postoperatively (p = 0.772). CV, CCT and endothelial cell loss were significantly lower in the one-handed group than in the two-handed group 1 week postoperatively (CV: p = 0.004; CCT: p = 0.046; endothelial cell loss: p = 0.021), but the above differences were absent 1 month postoperatively except for endothelial cell loss (endothelial cell loss: p = 0.038).

CONCLUSIONS

Both one-handed and two-handed coaxial phacoemulsification were effective and safe surgical techniques. However, the one-handed technique had the advantages of less trauma to the cornea and better early clinical outcomes than the two-handed technique for cataract patients within nuclear opalescence (NO) 3 grade ≤ 3.

Analysis of cataract surgery induced astigmatism: Two polar methods comparison

PURPOSE

Surgically induced astigmatism (SIA) caused by the incision after cataract surgery may be calculated to improve IOL toric power calculation and achieve better visual outcome. SIA could be determined as the difference between preoperative and postoperative keratometry expressed in polar values using different equations. The objective of this study is to compare the SIA calculated with two different polar value analysis methods [Method #1: KP (90)/KP (135) developed to be used with incisions placed at 90° and Method #2: AKP/AKP (+45) developed to be used independently of the incision location].

METHODS

Preoperative and one month postoperative data of 210 cataractous eyes (131 patients) undergoing uncomplicated cataract surgery were assessed. All incisions were performed at 11 o'clock (120°). No sutures were used in any patient. IOLMaster (Carl Zeiss Meditec, Dublin, Ireland) keratometry was used to polar calculation.

RESULTS

The average age was 66.25±12.33 years (range 22-89). SIA polar value data calculated with Method #1 were KP (90) -0.06±0.52D and KP (135) +0.05±0.91D and calculated with Method #2 were AKP -0.10±0.87D and AKP (+45) +0.02±0.02D. However, SIA value represented in traditional notation (diopters@axis in degrees) was the same value independently of the method used to calculate; +0.65@110.70°.

CONCLUSION

SIA value is independent of the polar method used to its calculation and slight variations in the incision position could be accepted without clinical relevant impact in SIA magnitude. Both methods [Method #1: KP (90)/KP (135) and Method #2: AKP/AKP (+45)] are useful to calculate SIA with superior incisions at 120°.

Clinical evaluation of surgery-induced astigmatism in cataract surgery using 2.2 mm or 1.8 mm clear corneal micro-incisions

AIM

To evaluate corneal astigmatism after phacoemulsification using 2.2 mm or 1.8 mm clear corneal micro-incisions and its effects on visual function.

METHODS

Sixty cases (60 eyes) with cataract were randomly divided into groups A (n=30) and B (n=30) respectively underwent 2.2 mm and 1.8 mm clear corneal tunnel incision phacoemulsification combined with folding intraocular lens implantation from the time direction of 11:00. On day 1 and at 1, 4, and 6wk after operation, patients' vision was measured and both the corneal curvature and corneal thickness (CT) were recorded using Pentacam.

RESULTS

The measured surgery-induced astigmatism (SIA) in both groups A and B peaked on day 1 after operation, and then gradually decreased and eventually stabilized in week 4. No statistically significant difference was found in corneal astigmatism between two groups (P>0.05). The measured corneal astigmatism at 4wk and 6wk postoperatively were 0.28±0.09 D and 0.27±0.10 D for groups A and 0.27±0.09 D and 0.25±0.10 D for groups B without statistically significant difference (P>0.05). In addition, no significant differences in visual acuity and CT were found between groups A and B before or after operation.

CONCLUSION

Both 2.2 mm and 1.8 mm micro-incision cataract surgeries result in relatively small SIA with no difference in visual function and corneal astigmatism between two surgery approaches. Thus, the two types of surgical systems are safe and efficient for cataract treatment, by which satisfactory uncorrected visual acuity can be regained early postoperatively.