Changes in shape and astigmatism of total, anterior, and posterior cornea after long versus short clear corneal incision cataract surgery

Analysis of surgically induced astigmatism of the anterior, posterior, and total cornea after implantable collamer lens implantation: a comparative study between temporal and superior clear corneal incisions

BACKGROUND

To comparatively analyze the surgically induced astigmatism (SIA) of the anterior, posterior, and total corneas of eyes undertaking implantable collamer lens (ICL) implantation with temporal or superior corneal incisions.

METHODS

One hundred and nine eyes of 109 patients who received ICL implantation were recruited: 40 eyes had temporal incisions and 69 eyes had superior incisions. Total corneal refractive power (TCRP); simulated keratometry of the anterior (Sim-KAnt) and posterior (Sim-KPost) corneal curvature; and astigmatism of the anterior (CAAnt), posterior (CAPost), and total (CATCRP) cornea were recorded through a Pentacam preoperatively and 3 months postoperatively. The SIA of the anterior, posterior, and total cornea were also compared between the two groups.

RESULTS

There were no significant intergroup differences for TCRP, Sim-KAnt, Sim-KPost, CAAnt, CAPost, or CATCRP, preoperatively. However, values of CAAnt, CAPost, and CATCRP with temporal incision were significantly higher than those parameters with superior incision postoperatively. All of the SIA of the anterior, posterior, and total cornea were significantly lower for temporal incision than those with a superior incision (p < 0.001, p = 0.006 and p = 0.001 respectively). Meanwhile, the superior incisions created against-the-rule (ATR) astigmatism, and temporal incisions always induce with-the-rule (WTR) astigmatism in total cornea.

CONCLUSIONS

A superior incision may be suitable for correcting WTR astigmatism, while a temporal incision for correcting ATR astigmatism when using a non-toric ICL. Meanwhile, temporal incision could be a better choice with little preoperative astigmatism or that preoperative astigmatism would be corrected with toric ICLs.

TRIAL REGISTRATION

Registration number: ChiCTR2100051739. Prospectively registered: 01 October 2021.

Does the Difference in Axial Length Affect the Refractive Outcome?

Background

The purpose of this study is to compare axial length (AL) and the refractive outcome after phacoemulsification surgery from 2014 to 2019 at Hospital Sultanah Nur Zahirah, Terengganu, Malaysia.

Method

This was a retrospective record review of all cataract patients who met the inclusion criteria and underwent uneventful superior wound phacoemulsification with nontoric intraocular lens (IOL) by a single surgeon from 2014 to 2019. Using optical biometry or immersion technique, the preoperative AL determined solely via the Sanders, Retzlaff and Kraff 2 (SRK2) formula was selected. The postoperative spherical equivalent (SE) at 6 weeks-12 weeks was retrieved. Using Statistical Package for the Social Sciences version 24.0, the mean differences between targeted and actual postoperative SE were analysed based on the AL.

Result

In this study, 490 eyes of 472 patients aged 25 years old-88 years old (mean age 65.72 years old [SD 8.83]) were involved. There were 162 eyes (33%) in Group A (< 23 mm), 189 eyes (39%) in Group B (23.01 mm-24.0 mm) and 139 eyes (28%) in Group C (> 24.0 mm). The mean AL was 23.63 mm (SD 1.19). The mean differences between the targeted and actual postoperative SE were: -0.09 D (SD 0.60) in Group A, -0.07 D (SD 0.53) in Group B and -0.16 D (SD 0.52) in Group C. No significant difference was found between these groups (P = 0.327).

Conclusion

There was no significant difference in the refractive outcome using the SRK2 formula in different ALs after phacoemulsification surgery. Hence, there is no reason to modify or adjust the targeted SE based on AL.

Laboratory Analysis of Causative Factors for the Final Incision Size due to Intraocular Lens Injector Insertion

Purpose

In intraocular lens (IOL) implantation, insertion of the IOL injector enlarges the clear corneal incision. A larger incision size (IS) is associated with a higher risk for surgically induced astigmatism and endophthalmitis. The goal of this study was to determine which parameters most influence the final IS.

Design

Experimental study.

Subjects

A total of 126 cadaver porcine eyes were included in this study.

Methods

We analyzed 409 clear corneal incisions made with 126 injectors from 13 injector models. We noted the vertical diameter and the tip angulation for every model. The corneal thickness of each incision location was measured using Scheimpflug tomography. The IS was measured before and after injector insertion and described as preoperative and final ISs, respectively. During surgery, the insertion depth and incision length were documented. A mixed effects model was applied to analyze the influence of the parameters on the final IS.

Main Outcome Measures

Influence on the final IS.

Results

Increases in the vertical diameter of the injector tip, the preoperative IS and the insertion depth, and a reduction of incision length were all significantly associated with increased final IS (P < 0.05). The conditional Pseudo-R2-Measure was 0.92. The preoperative IS had the largest standardized estimated effect on the final IS, followed by the vertical diameter of the injector tip, insertion depth, and lastly, incision length. Neither corneal thickness nor the tip angle of the injector had a significant effect on the final IS (P > 0.05).

Conclusions

The IOL injector's vertical diameter should be as small as possible to ensure a minimal final IS. The injector's insertion depth may be minimized, and the incision length should be long enough to reduce the final IS. Further studies are needed to confirm the findings in human autopsy eyes and in clinical practice.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article..

Clear corneal incision, an important step in modern cataract surgery: a review

A clear corneal incision (CCI) is the most commonly used entrance site in modern phacoemulsification cataract surgery. Despite some initial concerns about increased endophthalmitis rates through a self-sealing CCI, recent literature suggests that the risk of infection with proper wound construction and all other necessary precautions is minimal. The technique of creating a clear corneal incision has, with recent developments in corneal imaging, undergone critical appraisal leading to a better understanding of incision architecture. Many surgeons operate through smaller incisions, and they have a wide choice of surgical instruments to create their corneal incisions. The aim of this review is to discuss the history and the current status of clear corneal incision creation, the design and materials of surgical blades, and the current trends in manufacturing and sustainability. Although disposable instruments have some advantages and are very popular, recycling, if possible, and avoiding unnecessary plastic waste are important considerations. In any case, the step of CCI is a small one for the surgeon, but a big one for the eye. That is why it has to be done with the utmost precision and in-depth knowledge is important.

The Impact of Posterior Corneal Astigmatism on Surgically Induced Astigmatism in Cataract Surgery

PURPOSE

This study aimed to evaluate the changes in posterior corneal astigmatism after cataract surgery and provide a theoretical basis to accurately evaluate the total corneal astigmatism (TA) to be corrected before toric intraocular lens (IOL) implantation.

PATIENTS AND METHODS

Sixty-two patients (89 eyes) who underwent phacoemulsification combined with toric IOL implantation (AcrySof IQ Toric SN6AT2-T9) at Shanxi Eye Hospital between January 2017 and September 2018 were enrolled. Surgically induced astigmatism of the posterior cornea (SIAPA) was analysed using vector analysis during pentacam examination.

RESULTS

The vector variances of keratometric astigmatism (KA), TA, and posterior corneal astigmatism (PA) preoperatively and postoperatively in the "with-the-rule (WTR) astigmatism" group and "overall patient" group were statistically significant (P < 0.05). A statistically significant difference was observed between surgically induced KA (SIAKA) and surgically induced astigmatism of the total cornea (SIATA) for all patients, including those with WTR astigmatism. For all patients, SIAKA was less than SIATA by 0.05 ± 0.21 D, and for patients with WTR astigmatism, SIAKA was less than SIATA by 0.09 ± 0.22 D. For patients in the "against-the-rule (ATR) astigmatism" group, there were no statistically significant differences between SIAKA and SIATA, although SIAKA was greater than SIATA by 0.03 ± 0.18 D. When PA ≤0.4 D or KA ≤2.0 D, SIAPA can be ignored. However, when PA >0.4 D or KA >2.0 D, ignoring SIAPA caused by cataract surgery incision will cause SIAKA in patients with WTR astigmatism to underestimate SIATA, while SIAKA in patients with ATR astigmatism will cause an overestimation of SIATA.

CONCLUSION

SIA on the posterior corneal astigmatism may have a significant role on more precise planning of toric IOL implantation, especially in cases with higher preoperative anterior or posterior corneal astigmatism.

Predicting Residual Astigmatism in Cataract Surgery

The purpose of this review is to evaluate the prediction of postoperative residual astigmatism and to determine the best prediction method for astigmatism correction. In recent findings for residual astigmatism in non-toric monofocal intraocular lens (IOL) implanted eyes, vector analysis can be used to correctly evaluate residual astigmatism by decomposing it. In predicting residual astigmatism, the with-the-rule (WTR) and against-the-rule (ATR) astigmatism components can now be almost predicted. This may be due to advances in inspection equipment and surgical technique. However, there are still issues with the oblique astigmatism component. In addition, corneal astigmatism is the most important predictor of postoperative residual astigmatism, and other predictors, such as refractive astigmatism, age, and lens thickness, have also been mentioned. However, all but corneal astigmatism are questionable because of the possibility of confounding variables. Total corneal astigmatism is more accurate in predicting residual astigmatism than anterior corneal astigmatism. Several predictions of residual astigmatism have been reported, but complete prediction has not been possible. Further research is needed, especially in predicting oblique astigmatism. However, I emphasize that the accuracy of predicting WTR and ATR astigmatism has improved considerably and can be predicted using regression equations with total corneal astigmatism.

A Study Linking Axial Length, Corneal Curvature, and Eye Axis With Demographic Characteristics in the Emmetropic Eyes of Bangladeshi People

Background Axial length (AL) and corneal curvature (CC) are one of the furthest critical parameters for optometry and oculoplastic surgery. These two variables are crucial in biometry for accurately measuring the power of the intraocular lens in cataract surgery. This research aimed to determine the association linking axial length and corneal curvature with demographic characteristics in emmetropic eyes of Bangladeshi people. Methods This descriptive cross-sectional research was carried out among 200 emmetropic eyes of Bangladeshi people attending the Department of Ophthalmology at Rajshahi Medical College, Bangladesh, with different eye conditions, between July 2017 and June 2018. Data was gathered by conducting person-to-person interviews, checking visual activity using the Snellen chart, and measuring corneal curvature using an auto-keratometer and axial eyeball length using A-scan ultrasonography. Results A total of 200 attendances were studied, 90 males and 110 females. All were emmetropic. The age range was 21-52 years, and the highest contributors were in the 21-30-year age group. The association between right axial length and right corneal curvature shows a negative relation among both sexes. It was -0.61 (β-coefficient (β-coff)), and highly significant in females at -0.89 (β-coff). Additionally, the association between left axial length and left corneal curvature shows a negative relation of -0.65 (β-coff), which was again highly significant in females at -0.87 (β-coff). Both were not significant in males. There was no significant association linking axial length and eye axis in both sexes. The multivariate regression model was used to assess the p-value, and the regression model was adjusted by age. Conclusion Optical parametric measurement is a noninvasive diagnostic and assessment tool that might help in the actual measurement of intraocular lens implantation in cataract surgery and may also provide supplementary information to the researcher domain.

Prediction of residual astigmatism in cataract surgery at different diameter zones using optical biometry measurement

The studies for astigmatism prediction error at different diameters using optical biometry are scant. We investigated patients who underwent cataract surgery with monofocal, nontoric intraocular lens (IOL) from 2017 through 2019 in a medical center. Patients with prior refractive surgeries, corneal opacity, or surgical complications were excluded. Corneal astigmatism (CA) was measured using AL-Scan at 2.4- and 3.3-mm diameter zones and calculated using the Barrett toric calculator preoperatively and postoperatively. The mean absolute error and centroid prediction error for the two zones were computed using double-angle plots. In total, 101 eyes of 76 patients were analyzed. Mean patient age was 68.7 ± 9.3 years and mean preoperative CA power was 0.7 ± 0.5 D. The overall centroid prediction error a 3.3 mm (0.09 ± 0.58 D@25) was significantly lower than that at 2.4 mm (0.09 ± 0.68 D@87) on the X-axis (P = 0.003). The 3.3-mm measurement also had a lower centroid prediction error than the 2.4-mm did for eyes with against-the-rule (ATR) and oblique astigmatism (P = 0.024; 0.002 on X-axis, respectively). The 3.3-mm measurement provided a more accurate CA estimation than the 2.4-mm did, particularly for ATR astigmatism. Diameter zone and astigmatism type should be considered crucial to precise astigmatism calculation.

Incidence of Incision-Related Descemet Membrane Detachment Using Phacoemulsification With Trapezoid vs Conventional 2.2-mm Clear Corneal Incision: A Randomized Clinical Trial

Importance

The conventional 2.2-mm clear corneal incision is relatively narrow compared with the sleeves of Phaco handpieces, resulting in friction at the incision site and increased risk of incision-related Descemet membrane detachment (DMD). The modified 2.2-mm incision only enlarged internal width to 3.0 mm, forming a trapezoid incision shape, which may reduce the friction of surgical instruments and decrease the risk of incisional DMD.

Objective

To compare the incidence of incision-related DMD between eyes undergoing modified vs conventional 2.2-mm incision phacoemulsification for hard nuclear age-related cataract.

Design, Setting, and Participants

This double-masked, parallel randomized clinical trial was conducted from July 22, 2019, to January 22, 2020, at Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. The study included patients with age-related cataract and nuclear opalescence grade of 4.0 or greater based on the Lens Opacities Classification System III. Patients were enrolled in this study according to the following inclusion criteria: (1) age between 65 to 90 years; (2) pupil size of 6 mm or greater after dilation; (3) Lens Opacities Classification System III nuclear opalescence grade of 4.0 or more; and (4) corneal endothelial cell density greater than 1500 cells/mm2.

Interventions

Modified (enlarged internal width to 3.0 mm) or conventional 2.2-mm incision phacoemulsification with intraocular lens implantation.

Main Outcomes and Measures

Incidence of incision-related DMD at postoperative day 1.

Results

A total of 130 eyes of 130 patients were randomized into the conventional group (n = 65) or the modified group (n = 65). The mean (SD) age of participants was 74.5 (5.9) years and 74.3 (6.0) years in the conventional and modified groups, respectively. A total of 26 participants in the conventional group (40%) and 27 in the modified group (42%) were men. Compared with eyes in the conventional group, the incidence of DMD in eyes in the modified group was significantly lower at postoperative day 1 (difference, 26.15; 95% CI, 9.60-42.71; P = .003). The difference at postoperative day 7 was 16.92 (95% CI, 2.91-30.94; P = .02). The length of DMD (postoperative day 1: difference, 0.188; 95% CI, 0.075-0.301; P = .002) and maximal corneal thickness at incision site (postoperative day 1: difference, 0.032; 95% CI, 0.006-0.057; P = .02; postoperative day 7: difference, 0.019; 95% CI, 0.003-0.035; P = .02) were lower in the modified group, while visual quality parameter modulation transfer function (postoperative day 1: difference, -0.033; 95% CI, -0.064 to -0.001; P = .04) was higher. No difference was observed between the 2 groups in best-corrected visual acuity, central corneal endothelium loss, or surgically induced astigmatism at any follow-up time. There were no intraoperative complications in the 2 groups.

Conclusions and Relevance

These findings suggest that modified 2.2-mm trapezoid incision phacoemulsification reduces the incidence of DMD for hard nuclear age-related cataract at postoperative day 1 and might be considered in patients at high risk of incision-related DMD, although the clinical relevance cannot be determined with certainty from this trial.

Trial Registration

ClinicalTrials.gov identifier: NCT04014699.

Effect of corneal incision features on anterior and posterior corneal astigmatism and higher-order aberrations after cataract surgery

PURPOSE

To evaluate the influence of 2.2 mm clear corneal incision (CCI) features in surgically induced astigmatism (SIA) and higher-order aberrations (HOAs) after cataract surgery.

METHODS

Right eyes of 92 subjects receiving 2.2 mm incision cataract surgery were involved. A total of 38 eyes were categorized as the intact incision group, and 54 eyes were the defective incision group. Pre- and postoperative (1 month and 6 months) corneal astigmatism and HOAs on anterior and posterior corneal surfaces, corneal volume, and corneal thickness (CT) were measured using Pentacam. The CCI features including incision length (IL), incision angles, distance from incision to central cornea (Dis-En/Ex), and CT at incision site were quantified using AS-OCT.

RESULTS

The defective incision group showed shorter IL and larger incision angles [false discovery rate (FDR) - p < 0.05]. Changes in CT at incision site were more pronounced for the defective incision group (FDR - p < 0.05). Some SIA parameters were related to the certain specific CCI features, especially IL (FDR - p < 0.05). Both groups exhibited significant increased 6 mm posterior corneal tHOAs at 1 month (Bonferroni corrected - p < 0.01) and the defective incision group showed increased 6 mm posterior tHOAs at 6 months (Bonferroni corrected - p = 0.023). There were characteristic correlations between Zernike terms and CCI features including IL, CT, Dis-En/Ex, and incision angles at 1 month, especially over 6 mm zone.

CONCLUSION

The CCI deformities can affect corneal recovery and induce more HOAs at 1 month postoperatively. Such effects became minor, but could persist until 6 months. The IL combined with Angle-En/Ex was important factor influencing CCI integrity and corneal optical quality.

Long-Term Changes in Manifest Refraction Subsequent to Cataract Surgery

PURPOSE

To examine the long-term refractive changes after stabilization of surgically induced changes (SICs) subsequent to cataract surgery.

SETTING

Private hospital.

DESIGN

Case-control study.

METHODS

Manifest refraction of 300 eyes of 300 patients that underwent phacoemulsification and 300 eyes of 300 age- and sex-matched patients without surgery was examined the day on which SICs stabilized (baseline) and ≥7 years postbaseline using an autorefractometer. Refraction was divided into 3 components: spherical power (M), vertical/horizontal astigmatism (J0), and oblique astigmatism (J45) using power vector analysis, and the components were compared between the 2 time-points and between groups.

RESULTS

In the surgery group, the mean M and J45 did not change significantly between baseline and ≥7 years postbaseline, but the J0 significantly decreased between the 2 time-points (P < .001), indicating an against-the-rule (ATR) shift. In the non-surgery group, the mean M significantly increased and J0 significantly decreased between the time-points (P < .001), whereas J45 did not change significantly. The mean change in M between the 2 time-points was significantly smaller in the surgery group (P < .001), whereas the changes in J0 and J45 did not differ significantly between the time-points.

CONCLUSION

Spherical power did not change and refractive astigmatism significantly changed toward ATR astigmatism during the more than 7-year follow-up after stabilization of SICs in pseudophakic eyes, while hyperopic and ATR shifts occurred in phakic eyes, and the astigmatic changes were comparable between pseudophakic and phakic eyes.

Pupillary light response after cataract surgery in healthy patients

PURPOSE

To examine the changes in the pupillary light response after phacoemulsification and to compare the difference in the response among patients in different age categories.

STUDY DESIGN

Prospective observational study.

METHODS

Four-hundred twenty-two eyes of 422 patients in 3 age categories (60-69 years, 70-79 years, and 80-89 years) scheduled for phacoemulsification were consecutively enrolled. The eyes underwent examinations with an infrared pupillometer to obtain the parameters of the pupillary light response preoperatively and at 1 day and 1 and 3 months postoperatively. Differences in the parameters of the pupillary response were compared among 4 time intervals and the 3 age categories.

RESULTS

The mean maximum and minimum pupillary diameters significantly decreased at 1 day postoperatively and returned to the preoperative level by 1 month postoperatively (P<.0001). The mean percentage of pupillary constriction was significantly reduced at 1 and 3 months postoperatively compared with preoperatively and at 1 day postoperatively (P<.0001). The average pupillary constriction and dilation velocities were significantly lower at 1 and 3 months postoperatively than they were preoperatively and at 1 day postoperatively (P<.0001). The latency to constriction did not differ significantly among the time intervals. The percentage of pupillary constriction was significantly smaller, and the average constriction and dilation velocities were lower in association with higher age categories at all time intervals (P≤.0185).

CONCLUSION

The pupillary light response was impaired several months after cataract surgery and worsened with increasing patient age, indicating that cataract surgery may compromise the pupillary constriction and dilation functions in association with age.

Curved single-plane clear corneal incision made under anterior chamber collapse by aqueous humor aspiration prevents leakage after cataract surgery

PURPOSE

To evaluate the self-sealing on curved single-plane clear corneal incisions (CCIs) after cataract surgery. The collapse of the anterior chamber was made by aspirating the aqueous humor in order to make curved single-plane CCI.

METHODS

A retrospective study was conducted at Asai Hospital in Japan. There were 189 eyes of 132 patients scheduled from February to April 2017 for single-plane CCI. There were 175 eyes of 128 patients from February to April 2018 for curved single-plane CCI. Curved single-plane CCIs were made with aqueous humor aspiration via aqueous humor pipette, and single-plane CCIs were made without the aspiration. In case of leakage of aqueous humor from the CCI at the end of surgery, sutures were used. The main outcome measure was the proportion of sutures for CCI. Secondary outcomes included CCI length and surgically induced astigmatism (SIA) magnitude.

RESULTS

The proportions of suture in single-plane CCI and in curved single-plane CCIs were 25.4% (48/189) and 0% (0/175), respectively (p < 0.001). The length of curved single-plane CCI (2.06 ± 0.18 mm) was significantly greater than that of single-plane CCI (1.66 ± 0.12 mm; p < 0.001). The median postoperative SIAs of single-plane and curved single-plane CCIs were 0.64 D (n = 89) and 0.73 D (n = 85) for nasal incision, and 0.46 D (n = 100) and 0.47 D (n = 90) for temporal incision at examination 3 months after surgery, respectively, without significant change (p = 0.12 for nasal incision and p = 0.37 for temporal incision).

CONCLUSION

The curved single-plane CCI achieved by only aqueous humor aspiration showed significant effectiveness in self-sealing.

TRIAL REGISTRATION

UMIN clinical trials registry UMIN000032480, retrospectively registered on 6 May 2018.

Site of clear corneal incision in cataract surgery and its effects on surgically induced astigmatism

Clear corneal incision (CCI) is a commonly used surgical approach in cataract surgery. In this prospective study, we evaluated the effect of CCI site on surgically induced astigmatism (SIA) and other postoperative astigmatic changes. CCIs were constructed based on the steep meridian of the total corneal refractive power in the 4.0-mm-zone (TCRP_4.0), and patients were divided into four groups: temporal, superotemporal, superonasal, and superior according to the site of the incision. TCRP_4.0 analysis demonstrated a statistically significant reduction of astigmatism with superior incisions (P < 0.001), and the combined mean polar values for SIA changed significantly in the temporal (Hotelling T² = 1.977), superotemporal (Hotelling T² = 0.544), superonsal (Hotelling T² = 1.066), and superior incision groups (Hotelling T² = 1.134) (all P < 0.001). The posterior axis alignment should be considered in cataract surgery with CCI, and the SIA is affected by axis rotation, and incision orientation.

Multivariate Regression Analysis to Predict Postoperative Refractive Astigmatism in Cataract Surgery

Purpose

To assess the correlation between postoperative refractive astigmatism and preoperative parameters in cataract surgery.

Methods

Left eyes of 100 consecutive patients scheduled for cataract surgery with a 2.4 mm clear corneal incision were examined prospectively. Refractive astigmatism was measured using an autokerato/refractometer. Corneal astigmatism of the total cornea was calculated using a Scheimpflug camera. The vertical/horizontal component (J0) and oblique component (J45) of refractive and total corneal astigmatism were determined using power vector analysis. Refractive astigmatism at 8 weeks postoperatively was estimated using multivariate linear regression analysis. Independent variables analyzed included age, sex, refractive astigmatism, total corneal astigmatism, sphere, intraocular pressure, corneal thickness, anterior chamber depth, lens thickness, axial length, and pupil diameter.

Results

Multivariate regression analysis identified total corneal J0 and age as significant contributors to postoperative refractive J0 (P < 0.001 and P=0.029, respectively). The standard partial regression coefficients in the multiple regression analysis were 0.59 and −0.16 for total corneal J0 and age, respectively. Significant contributors to postoperative refractive J45 were total corneal J45 and lens thickness (P < 0.001 and P=0.015, respectively). The standard partial regression coefficients were 0.79 and −0.15 for total corneal J45 and lens thickness, respectively.

Conclusion

These results suggest that preoperative total corneal astigmatism is the most significant predictor of postoperative refractive astigmatism when performing astigmatism correction in cataract surgery.

Relationship between early structural changes at cornea incision sites and surgical outcomes after phacoemulsification

AIM

To assess the early structural changes at clear corneal cataract incision sites and surgical outcomes using anterior segment optical coherence tomography (AS-OCT).

METHODS

We evaluated 80 eyes of 59 patients who underwent phacoemulsification with a clear corneal incision. All incisions were evaluated 1wk, 1, and 3mo postoperatively using AS-OCT and analyzed regarding angle, length of the incision, maximal corneal thickness at the incision, and if present, corneal endothelial gap length and incision gap area. The patients were divided into two groups according to whether or not an endothelial gap was present at 1wk postoperatively (endothelial gap, group 1; no endothelial gap, group 2). We analyzed the difference in patient and surgical factors between the two groups, and compared the surgical outcome and the refractive outcome.

RESULTS

An endothelial gap was observed in 56 (70.0%) of 80 eyes at 1wk postoperatively but not at 3mo postoperatively. The mean patient age was significantly higher in group 1 than in group 2. The longer the length of the corneal incision and the steeper the incision angle, the greater the length and area of the endothelial gap. In group 1, the mean change in mean keratometry of the anterior cornea was significantly greater than in group 2, and the spherical equivalent (SE) and mean numerical error indicated significant myopic changes at 1wk postoperatively.

CONCLUSION

The risk of an endothelial gap increases with patient age and a long corneal incision and steep incision angle. The presence of an endothelial gap after surgery may affect the early postoperative corneal curvature and SE.

Corneal shape changes of the total and posterior cornea after temporal versus nasal clear corneal incision cataract surgery

Aim

To compare changes in the shape and astigmatism of the total and posterior cornea between eyes with a nasal clear corneal incision (CCI) and eyes with a temporal CCI in cataract surgery.

Methods

The left eyes of 100 patients undergoing phacoemulsification were randomly assigned to undergo a 2.4 mm nasal (nasal CCI group) or temporal CCI (temporal CCI group). Corneal astigmatic changes were compared between groups using power vector analysis, and corneal shape changes were compared using videokeratography maps at 2 days, and at 2, 4 and 8 weeks postoperatively.

Results

The mean J₀ and J₄₅ values of the total cornea were significantly greater in the nasal CCI group than in the temporal CCI group at 2 and 4 weeks postoperatively (p≤0.0392), but did not differ significantly between groups at 2 days and 8 weeks. The videokeratography maps revealed a wedge-shaped flattening in the total cornea and a steepening in the posterior cornea around the CCIs in both groups at 2 days postoperatively; those were more prominent in the nasal CCI group than in the temporal CCI group. The wound-related changes diminished by 8 weeks postoperatively in the total and posterior cornea, and were not markedly different between groups at 8 weeks postoperatively.

Conclusion

Corneal shape and astigmatic changes were comparable between groups at 8 weeks postoperatively, although the changes were greater after nasal CCI than after temporal CCI in the early postoperative periods, indicating that nasal or temporal CCI can be selected based on the surgeon’s preference.