Correlation of corneal thickness and volume with intraoperative phacoemulsification parameters using Scheimpflug imaging and optical coherence tomography

Corneal Endothelial Cell Loss After Endocapsular and Supracapsular Phacoemulsification: The PERCEPOLIS Randomized Clinical Trial

PURPOSE

Subluxation techniques are superior to divide-and-conquer in procedure duration, pain, and ultrasound quantity, but their safety in endothelial cell loss (ECL) is unclear. This randomized single-blind noninferiority clinical trial aimed to determine whether subluxation supracapsular phacoemulsification techniques are inferior to a reference endocapsular technique (divide-and-conquer) regarding postoperative corneal ECL.

METHODS

Patients (aged18 years or older) with greater than +0.2 logarithm of the minimum angle of resolution best spectacle-corrected visual acuity and normal to severe density cataract were randomized to subluxation or divide-and-conquer phacoemulsification in 2015 to 2016. Follow-up with ophthalmic tests was conducted on day 4 and months 1, 3, and 12. The primary study outcome was ECL at all time points. Secondary study end points were operative variables, including effective phaco time and procedure duration. A clinically relevant noninferiority ECL limit was established on the basis of the literature.

RESULTS

In total, 292 patients (mean age, 73 yrs; 59% female) were randomized and underwent subluxation (n = 148) or divide-and-conquer (n = 144). Day 4 and month 1, 3, and 12 data were available for 243, 270, 275, and 198 patients, respectively. The unexpectedly high dropout at 12 months meant that the 12-month ECL data could only be assessed qualitatively. Surgery was successful in all patients. Subluxation was noninferior to divide-and-conquer in ECL. Effective phaco times were similar, but subluxation associated with shorter procedure duration.

CONCLUSIONS

The subluxation technique was noninferior to divide-and-conquer regarding postoperative ECL, at least in the first 3 months, and associated with reduced intervention time. Subluxation techniques may be suitable alternatives to endocapsular techniques.Clinical Trial Registration-URL: ClinicalTrials.gov. Unique identifier: NCT02535819.

Peripheral corneal thickness and associated factors - results from the population-based German Gutenberg Health Study

PURPOSE

Changes in peripheral corneal thickness are described in various corneal diseases such as corneal ectasia. However, few data exist describing the increase in corneal thickness from central to peripheral and reporting the normal distribution of corneal thickness in rings around the corneal centre. The aim of this study was to report these cornea characteristics and investigate associated factors in a population-based setting.

METHODS

The Gutenberg Health Study is a prospective, population-based study examining participants in a 5-year follow-up (age range 40-80 years) using Scheimpflug imaging. Corneal thickness was assessed in each participant at the apex, as well as in the corneal centre (thinnest corneal thickness) and in rings with 2, 4, 6, 8 and 10 mm diameter around the corneal centre, and the increase in corneal thickness towards the periphery. The relationship between corneal thickness at these locations and possible associated factors was determined using linear regression models. For this purpose, general and ocular parameters were included.

RESULTS

A total of 9729 participants were included in the present analysis (4874 women, age 59.2 ± 10.8 years). Multivariable analysis showed a correlation between the increase in corneal thickness in the circles from 0 to 10 mm (diameter) and the following parameters: age (B = -0.24 µm per year, p < 0.001); body height (B = -0.04 µm, p = 0.005); smoking (B = -0.72 µm, p < 0.001); spherical equivalent (B = -0.70 µm per dioptre, p < 0.001); white-to-white distance (B = -0.75 µm/mm, p < 0.001); mean corneal radius (B = -3.61 µm/mm, p < 0.001); intraocular pressure (B = -0.12 µm/mmHg, p < 0.001); glaucoma (B = -1.94 µm, p < 0.001); and pseudophakia (B = 0.89 µm, p < 0.001).

CONCLUSION

The results of the present study suggest that several general and ocular parameters are associated with peripheral corneal thickness. In the context of diagnosing glaucoma, a smaller increase in corneal thickness towards the periphery might be a new additional marker.

Defining the surgical footprint in cataract surgery: patient-related outcomes dependent on the experience of the surgeon

PURPOSE

To investigate which patient-related outcomes are dependent on the experience of the cataract surgeon.

METHODS

The study was designed as a prospective observational study. Novice (<150 surgeries performed) and experienced (>1000 surgeries performed) cataract surgeons from the Department of Ophthalmology, Rigshospitalet - Glostrup and Nordsjaellands Hospital - Hillerød were included in the study. Patients operated by the included surgeons were examined preoperatively, 1 day, 3 days, and 3 weeks after standard, noncomplicated cataract surgery. Primary outcomes were change in central corneal thickness and endothelial cell loss. Secondary outcomes were best-corrected visual acuity, intraocular pressure, aqueous flare, central macular thickness, and surgical complications.

RESULTS

Surgery performed by novice surgeons resulted in significantly lower visual acuity (mean -3.6 letters (Early Treatment Diabetic Retinopathy Study (ETDRS)); 95% CI: -7.3; -0.4, p = 0.03) and greater corneal thickness (mean 26.7 µm; 95% CI: 6.8; 46.6, p = 0.01) on the first day postoperative than surgery performed by experienced surgeons.

CONCLUSION

The experience of the cataract surgeon affected visual acuity and central corneal thickness in the immediate postoperative period. In the future, these patient-related outcomes may be used to assess the technical proficiency of surgical trainees and investigate the effect of different training programs.

Simultaneously Monitoring Whole Corneal Injury with Corneal Optical Density and Thickness in Patients Undergoing Cataract Surgery

To pursue the least corneal implication during cataract surgery, this study aimed to monitor corneal wound injury after cataract surgery with a novel method. The prospective cohort study involved thirty-two patients, who were assessed by a Scheimpflug tomography AxL^® (Oculus GmbH, Wetzlar, Germany) via the following two kinds of indices: whole corneal optical density (COD) and corneal thickness (CT), two weeks before and one month after cataract surgery. The results of the COD revealed that corneal annuli 0.0–2.0 mm and 2.0–6.0 mm, and the average and maximal values at the incisional site significantly increased postoperatively. Also, the anterior and central stroma of 0.0–2.0 mm, and all three depths of 2.0–6.0 mm, increased remarkably after the operation. For the CT, all ranges of diameters plus incisional sites showed significant increases postoperatively. Furthermore, we analyzed the differences (delta) of COD and CT between pre- and post-operation, and found significant correlations between the delta of COD and the delta of CT, regarding annuli 0.0–2.0 mm, 2.0–6.0 mm, and 6.0–10.0 mm, but no correlation at the incisional site, with either average density or maximal density, was detected. We concluded that whole COD and CT, especially at the central zones of the cornea (annulus < 6 mm), are both valuable parameters in the assessment of corneal damage post-cataract surgery, and are independent indices at the incisional site.

Is the Corneal Thickness Profile Altered in Diabetes Mellitus?

Purpose: To investigate the influence of chronic hyperglycemia in diabetes mellitus (DM) on spatial corneal thickness distribution and to analyze the influence of disease-specific factors. Methods: DM patients and healthy subjects were matched according to age and intraocular pressure (IOP). In diabetics, disease duration, DM type, and HbA_1c value were assessed. Spatially resolved corneal thickness was measured by Pentacam HR. Thinnest corneal thickness (TCT) and peripheral pachymetry of concentric circles around TCT were determined. The Dynamic Scheimpflug Analyzer Corvis ST (CST) was used to measure the parameter pachy slope, which is an indicator of the change of corneal thickness from the apex to the periphery. Results: 59 DM patients and 57 healthy subjects were included. Age (P = .486) and IOP (P = .154) were not different between the groups. In DM, pachy slope was significantly higher than in healthy subjects (41.1 ± 9.87 vs. 35.18 ± 10.64 μm, P = .004). Also, the differences between TCT and the average of peripheral corneal thickness of concentric circles with a diameter of 2 mm (10.3 ± 1.7 vs. 9.3 ± 3.8 μm, P < .001) to 6 mm (82.2 ± 12.4 vs. 76.8 ± 12.6 μm, P = .011) were increased in patients. Changes in thickness profile were associated with HbA_1c value and presence of diabetic retinopathy or maculopathy. Conclusion: In DM, a stronger peripheral corneal thickness increase was detectable. This change was shown using the novel CST parameter pachy slope and confirmed by Pentacam readings. These alterations might affect IOP and biomechanical measurements, and influence refractive procedures.

Active-fluidics-based torsional phacoemulsification in diabetic eyes: A prospective interventional study

Purpose

To compare the outcomes of active-fluidics based torsional phacoemulsification in diabetics and nondiabetics using a balanced tip.

Methods

Two hundred and forty-eight patients undergoing senile cataract surgery using torsional phacoemulsification on an active-fluidics-based platform from December 2016 to August 2017 were included in this prospective, nonrandomized, interventional cohort study; of the 248 patients, 54 were controlled diabetics and 194 were nondiabetics. Intraoperative parameters such as cumulative dissipated energy (CDE), total ultrasound time, torsion usage time, torsion amplitude, aspiration time, and fluid usage were documented and compared. Endothelial cell loss (ECL) and central corneal thickness (CCT) were evaluated at 1 month postoperatively.

Results

Diabetics and nondiabetics did not differ in CDE, total ultrasound time, torsion amplitude, aspiration time, fluid usage, endothelial cell count, and CCT. ECL on Day 1 (10.2 ± 8.0%) and Day 30 (11.05 ± 8.3%) were significantly higher in diabetics (P = 0.025 and P = 0.045, respectively). There was an increase in CCT on Day 1 (P = 0.018), which settled by Day 30. Grade 4 cataracts in diabetics had significantly higher CCT at Day 1 (P = 0.032) and Day 30 (P = 0.007). In the diabetic subgroup, Grades 3 and 4 cataracts required lower CDE (P < 0.001) and Grade 4 cataracts showed higher ECL than others till 1 month of follow-up (P < 0.05).

Conclusion

Intraoperative and postoperative parameters after torsional phacoemulsification are comparable in diabetics and nondiabetics. Endothelial changes and pachymetry may be related to the grade of cataract in diabetics.

Central corneal thickness and corneal volume changes in eyes with and without pseudoexfoliation after uneventful phacoemulsification

AIM

To investigate the effects of uneventful phacoemulsification on central corneal thickness (CCT) and corneal volume (CV) in pseudoexfoliative eyes during a 3 months postoperative period and compare these changes to eyes without pseudoexfoliation (PEX) syndrome. Another purpose of this study was to compare the CCT measurements done by ultrasound pachymetry (UP) with those done by the Oculus Pentacam.

MATERIAL AND METHOD

A total of 42 eyes of 42 consecutive patients with cataracts and PEX syndrome that underwent uneventful phacoemulsification were enrolled in this prospective study. A control group of 42 eyes of 42 patients with cataracts/without PEX was employed for comparison. CV and CCT measurements were obtained preoperatively and at 1 and 3 months postoperatively with the Pentacam. CCT values were also measured with UP. T test and Wilcoxon sign test were used to compare the variables.

RESULTS

The mean age of the patients was 72.1 ± 8.3 and 66.6 ± 9.6 years in PEX and non-PEX group, respectively. In both groups, there were no significant differences between preoperative and postoperative CV (Fig. 1), CCT by the Pentacam (Fig. 2) and CCT by UP (Fig. 3) values (p > 0.05). CCT measurements obtained by two devices were also similar, and there were no statistically significant differences (p > 0.05). Changes in CV and CCT remained stabile at 3 months postoperatively.

CONCLUSION

Eyes with and without PEX syndrome exhibit similar corneal features before and after phacoemulsification. A surgery in early stages of cataracts in PEX syndrome, not only provides a non-complicated surgery, but also leads to a less damaged cornea similar to eyes without PEX.

Comparison of specular microscopy and ultrasound pachymetry before and after cataract surgery

PURPOSE

To compare specular microscopy (Topcon SP-3000P, Topcon Corporation, Tokyo, Japan) and ultrasound (US) technology when evaluating central corneal thickness (CCT) prior to and after phacoemulsification.

METHODS

Corneal edema was assessed in phacoemulsification patients due to senile cataract by measuring CCT preoperatively and 1 day, 1 month, and 3 months postoperatively. Bland-Altman analysis was performed to assess interchangeability between pachymetry techniques for each visit. Repeated measures analysis of variance was performed to evaluate variation in CCT agreement depending on the degree of corneal edema.

RESULTS

One hundred and eighteen patients aged 73.9 ± 10.1 years were recruited. Topcon SP-3000P provided significant (p < 0.0001) lower CCT values than US with and without induced corneal edema. Mean differences between CCT techniques for baseline, 1 day, 1 month and 3 months after cataract surgery were -28.9 ± 22.6, -30.5 ± 41.4, -32.3 ± 16.2 and -33.0 ± 16.9 μm, respectively. The systematic bias observed was not significantly different among the 4 visits (p = 0.59). The estimated limits of agreement (based on 1.96 standard deviation) were substantial, being 90.5, 165.8, 64.9 and 67.5 um at baseline, 1 day and 1 and 3 months.

CONCLUSIONS

Topcon SP-3000P provides similar systematic bias in comparison with US technique for CCT measurements regardless of the degree of corneal edema after phacoemulsification, which should be reduced after applying a constant calibration adjustment of ∼30 μm. However, interchangeability between techniques may be still limited by the notable random measurement error.