Evaluation of corneal biomechanical parameters after simultaneous phacoemulsification with intraocular lens implantation and limbal relaxing incisions

Usefulness of Intraocular Pressure With the Ocular Response Analyzer to Predict Postoperative Hypotony Complications in Glaucoma

Purpose

To investigate the usefulness of intraocular pressure (IOP) using the ocular response analyzer to predict the occurrence of hypotony complications following trabeculectomy or bleb needling revision with mitomycin C.

Methods

This study included 66 eyes of 66 patients who underwent trabeculectomy (58 eyes of 58 patients) or bleb needling (8 eyes of 8 patients) with mitomycin C. A significant predictor of hypotony complications was identified from (1) operation (trabeculectomy or bleb needling), (2) age, (3) sex, (4) disease type (primary open-angle glaucoma, primary angle closure glaucoma, or exfoliation glaucoma), (5) lens status (phakia or pseudophakia), (6) preoperative Goldmann applanation tonometry IOP, (7) preoperative central corneal thickness, (8) preoperative axial length, (9) preoperative anterior chamber depth, (10) preoperative corneal hysteresis, (11) preoperative corneal resistance factor, (12) preoperative corneal compensated IOP (IOPcc), and (13) minimum IOP (IOP value when hypotony complications occurred, otherwise the minimum IOP during 3 months from trabeculectomy or bleb needling) using multivariate logistic regression.

Results

The probability of the occurrence of hypotony complications tended to increase by applying higher cutoff values to preoperative Goldmann applanation tonometry IOP and IOPcc, but not lower cutoff values to the minimum IOP. Multivariate logistic regression suggested that higher preoperative IOPcc and pseudophakia were significant predictors of the occurrence of hypotony complications (P = 0.0062 and 0.0069, respectively).

Conclusions

Higher preoperative IOPcc and pseudophakia were significant predictors of the occurrence of hypotony complications.

Translational Relevance

It is useful to measure IOP using the ocular response analyzer before trabeculectomy.

Evaluation of corneal hysteresis after pars plana vitrectomy combined phacoemulsification and intraocular lens implantation

We evaluated the early effects of pars plana vitrectomy (PPV) on corneal biomechanics by comparing corneal hysteresis (CH) after cataract surgery (phacoemulsification and aspiration with intraocular lens implantation; PEA + IOL) alone and PPV combined with cataract surgery. This study included 20 eyes (18 patients), who underwent cataract surgery alone (PEA + IOL group), and 28 eyes (27 patients) who underwent PPV combined with cataract surgery (PPV triple group). The CH was 11.1 ± 1.1, 10.4 ± 1.1, and 11.0 ± 1.0 mmHg in the PEA + IOL group and 11.0 ± 1.4, 9.8 ± 1.4, and 10.6 ± 1.6 mmHg in the PPV triple group, preoperatively, at 2 weeks, and 3 months after surgery, respectively. The CH was not significantly different after surgery in the PEA + IOL group, but decreased significantly in the PPV triple group 2 weeks following surgery (p < 0.01). Intraocular pressure (IOP) and central corneal thickness (CCT) did not change significantly after surgery in either group. Preoperatively, there was a positive correlation between CH and CCT in the PPV triple group, but the correlation disappeared postoperatively. In PPV combined with cataract surgery, CH temporarily decreased postoperatively, independent of IOP and CCT. Removal of the vitreous may reduce the elasticity and rigidity of the entire eye.

Corneal Biomechanical Changes After Uneventful Phacoemulsification in Patients With Type 2 Diabetes Mellitus and Patients Without Diabetes

PURPOSE

To compare corneal biomechanical changes after uneventful phacoemulsification cataract surgery between type 2 diabetic (DM) and nondiabetic patients.

METHODS

Forty-four diabetic (44 eyes) and 44 (44 eyes) age and sex-matched non-DM controls with age-related cataract were enrolled in this prospective observational study. Corneal hysteresis (CH), corneal resistance factor (CRF), and corneal-compensated intraocular pressure (IOPcc) were evaluated by using the ocular response analyzer; central corneal thickness was recorded by using the Pentacam HR. Patients were evaluated preoperatively and 1 and 6 months after surgery.

RESULTS

In the DM group, CH was observed to be significantly lower than preoperative value (9.8 ± 1.5 mm Hg) at 1 month (9.4 ± 1.2 mm Hg, P = 0.040), but not at the 6-month follow-up (9.6 ± 1.6 mm Hg, P = 0.437),whereas it did not change significantly in the non-DM group (preoperative 9.8 ± 1.3 mm Hg vs. 1 month 9.6 ± 1.1 mm Hg vs. 6 months 10.1 ± 1.1 mm Hg, P > 0.05). CRF was significantly lower than the preoperative values at 1 and 6 months in both groups (P ≤ 0.001). Postoperative CH change was significantly associated with preoperative CH (P < 0.001), preoperative IOPcc (P = 0.004), and IOPcc change (P < 0.001), whereas CRF change was only correlated with preoperative CRF (P < 0.001). There was a significant postoperative IOPcc reduction 6 months after surgery (P < 0.001) in both DM and non-DM groups; however, central corneal thickness was not found to significantly change in the postoperative period (P > 0.05).

CONCLUSIONS

This study showed that phacoemulsification causes a significant and persistent decrease in intraocular pressure and CRF in both groups, whereas CH recovered to preoperative values, although more slowly in patients with diabetes.

Changes in Corneal Biomechanics and Intraocular Pressure Following Cataract Surgery

PURPOSE

To investigate the effects of cataract surgery on corneal biomechanics and intraocular pressure (IOP) measured with the updated Corvis ST tonometer (CST).

DESIGN

Prospective, interventional case series study.

METHODS

This study included 39 eyes of 39 cataract patients. CST measurements were performed at presurgery (Pre) as well as 1 week (1W), 1 month (1M), and 3 months (3M) postsurgery. The following CST parameters were recorded: deformation amplitude max (DA max), DA ratio max 1 mm and 2 mm, integrated radius, stiffness parameter at applanation 1 (SP A1), Ambrosio relational thickness to the horizontal profile (ARTh), Corvis biomechanical index (CBI), central corneal thickness (CCT), noncorrected intraocular pressure (IOPnct), and biomechanically corrected IOP (bIOP). IOP was also measured with Goldmann applanation tonometry and the noncontact tonometer CT-90A. All measurements were compared at each period using the linear mixed model, with and without adjustment for bIOP and CCT.

RESULTS

All IOP measurements decreased over time (P < .01). CCT was increased at 1W and 3M (P < .01), whereas ARTh was decreased at 1W and 1M (P < .01), but returned to its Pre level at 3M. DA max and Integrated radius were increased at 3M (P < .01), whereas SP A1 was decreased at 3M (P < .01). CBI was increased at 1W (P < .01), but returned to its Pre level at 1M.

CONCLUSIONS

IOP and Corneal biomechanical properties are changed after cataract surgery. In particular, SP A1 decreases while DA max and integrated radius increase, even at 3M, suggesting a less stiff cornea.

Corneal biomechanical properties changes after coaxial 2.2-mm microincision and standard 3.0-mm phacoemulsification

AIM

To compare the changes in corneal biomechanics measured by ocular response analyzer (ORA) after 2.2-mm microincision cataract surgery and 3.0-mm standard coaxial phacoemulsification.

METHODS

The prospective nonrandomized study comprised eyes with cataract that had 2.2-mm coaxial microincision or 3.0-mm standard incision phacoemulsification. The corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) were measured by ORA preoperatively and at 1d, 1-, 2-, 3- and 4-week postoperatively. Results were analyzed and compared between groups.

RESULTS

In both groups, CH decreased in the immediate postoperative period (P<0.05), returned to the preoperative level at one week (P=0.249) in the 2.2-mm group, and at two weeks in the 3.0-mm group (P=0.264); there was no significant change in CRF values. In 2.2-mm group, mean IOPcc and IOPg increased at 1d postoperatively (both P<0.05), and returned to preoperative level at one week (P=0.491 and P=0.923, respectively). In 3.0-mm group, mean IOPcc and IOPg increased at 1d and 1wk postoperatively (P=0.005 and P=0.029, respectively), and returned to preoperative level at 2wk (P=0.347 and P=0.887, respectively).

CONCLUSION

Significant differences between preoperative and postoperative corneal biomechanical values were found for CH, IOPcc and IOPg. But the recovery time courses were different between the two groups. The 2.2-mm coaxial microincision cataract surgery group seemed recovery faster compared to the 3.0-mm standard coaxial phacoemulsification group.

Clinical utility of femtosecond laser-assisted astigmatic keratotomy after cataract surgery

PURPOSE

To examine the clinical utility of femtosecond laser-assisted astigmatic keratotomy (FSL-AK) for eyes after cataract surgery.

METHODS

Eight eyes of 6 patients with an intraocular lens and corneal astigmatism of 2.0 diopters (D) or more underwent FSL-AK. The mean preoperative manifest cylindrical refraction was 2.88 ± 0.64 D and the mean corneal astigmatism was 2.84 ± 0.83 D. Paired symmetrical arcuate incisions were created with the same settings, except for the incision depth. Uncorrected distance visual acuity (UDVA), manifest cylindrical power, and surgically induced astigmatism (SIA) were measured at 1 day, 1 week, and 1 month postoperatively. Fourier analysis of corneal topography and incision depths measured with anterior-segment optical coherence tomography were evaluated 1 month postoperatively.

RESULTS

In all eyes, the UDVA improved at 1 week and 1 month postoperatively, and the manifest cylinder also decreased postoperatively, while the SIA showed overcorrections in 6 eyes. Fourier analysis showed decreases in spherical and regular astigmatic components and increases in higher-order irregularity. The mean incision depth was measured as 60 µm deeper than the intended depth.

CONCLUSION

The FSL-AK effectively reduced corneal astigmatism and improved the UDVA, although it was demonstrated that the deeper incisions led to overcorrection.

Effects of phacoemulsification surgery on ocular hemodynamics

AIM

To evaluate the possible effects of phacoemulsification cataract surgery on ocular hemodynamics.

METHODS

In this prospective study, intraocular pressure (IOP), pulsatile ocular blood flow (POBF), and ocular pulse amplitude (OPA) were measured pre-operatively (baseline) and at 1 week and 3 weeks postoperation in 52 eyes of 26 patients (mean age 63.15±10.25 years) scheduled for unilateral phacoemulsification cataract surgery with intraocular lens implantation. In all of the eyes, a blood flow analyzer (Paradigm DICON; Paradigm Medical Industries Inc.; USA) was used to obtain measurements of IOP, POBF, and OPA. The data obtained from operated eyes were compared statistically to untreated fellow phakic eyes of the patients.

RESULTS

For operated eyes, the mean baseline IOP, POBF, and OPA values were 15.9±4.64mmHg, 17.41±4.84µL/s, and 2.91±1.12mmHg, respectively. The IOP, POBF, and OPA values were 17.19±4.34mmHg, 17.56±6.46µL/s, and 3.12±1.1mmHg, respectively, in the nonoperated control eyes. Statistically significant differences from baseline measurements were not observed 1 week and 3 weeks postoperation for the operated or nonoperated eyes. There were also no statistically significant differences in any measurements between the operated and nonoperated eyes in all the examination periods (P>0.05 for all).

CONCLUSION

Uncomplicated phacoemulsification surgery does not affect ocular hemodynamics in normotensive eyes with cataracts.

Influence of corneal biomechanical properties on surgically induced astigmatism in cataract surgery

PURPOSE

To perform an overall follow-up of the morphologic, optical, and biomechanical properties of the cornea to determine new parameters influencing the refractive outcomes of cataract surgery.

DESIGN

Clinical study.

METHODS

Patients scheduled for cataract surgery were assessed for surgically induced corneal astigmatism (SIA) and higher-order aberrations, (HOAs) using a Scheimpflug rotating camera (Pentacam) together with corneal imaging by optical coherence tomography (Spectralis) and biomechanical analysis by the Ocular Response Analyzer preoperatively and 1, 7, and 30 days postoperatively. The central and peripheral corneal thicknesses; incision width, length, and architecture; corneal hysteresis (CH); and corneal resistance factor (CRF) were computed to identify new parameters influencing corneal optical changes that determine the final refractive result.

RESULTS

The study enrolled 40 patients (40 eyes). The SIA and HOAs were significantly lower after microincision surgery (≤ 2.2 mm) than after small-incision surgery (2.75 mm) (both P<.01). The CRF was significantly reduced with a direct corneal incision compared with a constructed incision (P<.01). Multivariate analysis showed that SIA was correlated not only with incision width (P<.05) but also with preoperative CH (P<.01). Corneal 3rd-order trefoil depended on incision width (P<.01).

CONCLUSIONS

In addition to the well-known influence of incision size on SIA, CH also modulates optical changes. The biomechanical features of the cornea should be taken into account preoperatively to better predict the refractive outcomes of cataract surgery.