Standard Coaxial Phacoemulsification Research Articles

Evaluation of corneal biomechanical properties after uneventful standard coaxial phacoemulsification surgery

Evaluation of corneal biomechanical properties after uneventful standard coaxial phacoemulsification surgery

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

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. 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. 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). 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.

Dry Eye Changes after Phacoemulsification and Manual Small Incision Cataract Surgery (MSICS)

Purpose: Evaluation of tear film stability and tear secretion after phacoemulsification and manual small incision cataract surgery (MSICS). Design: Prospective comparative randomized clinical study. Subject and methods: 40 Patients included in this study divided into, Group A: 20 eyes with phacoemulsification. Group B: 20 eyes with MSICS. All patients had full ophthalmic examination including Tear film break-up time (TF-BUT), schirmer test, corneal fluorescein staining and dry eye symptoms recorded pre- and post- operatively. All patients were done by the same surgeon randomly selected standard coaxial phacoemulsification or MSICS. Results: The mean age in group A 55.8 ± 15.8 while, 60.65 ± 9.2 in group B. Most of patients in group B were females (90%) versus 45% in group A with statistically significant difference (p-value < 0.05). Grade of dry eye symptoms (DES) has significantly increased 1 week after each procedure and remained increased after 4 weeks of surgery. After 3 months, the grade of DES has decreased again and returned to near baseline data. There was no statistically significant difference between both groups regarding TF-BUT, Cornea fluorescein staining, and Schirmer test. Conclusion: The present study has shown that MSICS is as effective as phacoemulsification with no difference between both techniques as regarding effect on tear film stability and tear secretion.

Real-time intraocular pressure measurement during phacoemulsification in dogs &lt;i&gt;ex vivo&lt;/i&gt;

This study was performed to evaluate changes in intraocular pressure (IOP) during standard coaxial phacoemulsification using 4 different bottle heights (BHs) and 2 different incision sizes. Coaxial phacoemulsification was performed with a venturi-based machine in 8 enucleated canine eyes through 3.0 and 3.2 mm clear corneal incisions (CCIs). A pressure transducer inserted in the peripheral cornea monitored the IOP in real-time. The surgery was subdivided into 4 stages: sculpt-segment removal, irrigation/aspiration, capsular polishing and viscoelastic removal. The mean IOP and the difference between the maximum and minimum IOPs were calculated at each stage and compared. The ultrasound time and volume of irrigation fluid used were recorded. The mean IOP increased with an elevation in the BH. The mean IOP in the irrigation/aspiration stage was significantly higher than that in the sculpt-segment removal stage at the same BH. The difference between the maximum and minimum IOP at each stage was greater in the 3.2 mm than the 3.0 mm CCIs, although the mean IOP was lower with the 3.2 mm than the 3.0 mm CCIs. The ultrasound time and irrigation fluid volume were greater with the 3.2 mm than the 3.0 mm CCIs. Therefore, fluidic parameters during each stage could be reassessed and adjusted to reduce complications arising from an elevated IOP. Phacoemulsification with 3.0 mm CCIs at a lower BH might lead to less stress on the eye from IOP fluctuations, ultrasound energy and irrigation fluid.

Pupil-expansion ring implantation through a 0.9 mm incision

Disposable square and hexagonal Bhattacharjee pupil-expansion rings are made of 5-0 nylon, have notches at the corners, and flanges at the sides in a single 0.1 mm thin plane. To insert the ring, a flange is held with a 23-gauge forceps and the ring is inserted through a 0.9 mm (20-gauge) or larger main- or side-port incision. Alternate flanges are tucked under the iris using a Kuglen hook. A 23-gauge forceps and an iris hook can also be used to tuck the flanges bimanually. The ring is removed by disengaging 2 notches and pulling it out of a 0.9 mm (20-gauge) incision. No snagging of the incision occurs at insertion or removal. No injector is required. The device is useful in standard coaxial phacoemulsification, femtosecond laser-assisted cataract surgery, biaxial microincision cataract surgery (MICS), coaxial sub-2.0 mm MICS, and small-pupil microincision vitreous surgery and in eyes with shallow anterior chambers. Dr. Bhattacharjee has a pending international patent application (PCT-WIPO) for the pupil-expansion devices.

Comparison of Surgically-induced Astigmatism after Combined Phacoemulsification and 23-Gauge Vitrectomy: 2.2-mm vs. 2.75-mm Cataract Surgery

PurposeThe 2.2-mm microincision cataract surgery and small-gauge vitrectomy system is known to result in less surgically-induced astigmatism (SIA) in comparison to conventional surgical methods. We compared the amounts of SIA after combined phacoemulsification and 23-gauge transconjunctival sutureless vitrectomy (23G-TSV) using the 2.2-mm microincision and 2.75-mm standard incision methods.MethodsWe studied 59 patients (61 eyes) who underwent combined phacoemulsification and 23G-TSV from November 2008 to September 2012. Twenty-eight patients (28 eyes) underwent 2.2-mm microincision coaxial phacoemulsification, and 31 patients (33 eyes) underwent 2.75-mm standard incision phacoemulsification. SIA was evaluated using Naeser's polar method with the simulated keratometric values obtained from corneal topography. Preoperative and 1-week and 1-month postoperative KP (Naeser's polar value along the specific axis) and ΔKP values were compared between the 2.2-mm microincision and 2.75-mm standard incision groups.ResultsOne week after surgery, both groups exhibited similar amounts of SIA (-ΔKP[120], 0.40 ± 0.41 vs. 0.51 ± 0.56 diopters [D]; p = 0.390). One month after surgery, however, the amount of SIA was significantly smaller in the 2.2-mm microincision group as compared to the 2.75-mm standard incision group (-ΔKP[120], 0.31 ± 0.54 vs. 0.56 ± 0.42 D; p = 0.045).ConclusionsIn combined phacoemulsification with 23G-TSV, 2.2-mm microincision coaxial phacoemulsification induces less SIA than does 2.75-mm standard coaxial phacoemulsification.

Stereo-PIV study of flow inside an eye under cataract surgery

We measured velocity distributions in the anterior chamber of porcine eyes under simulated cataract surgery using stereoscopic particle image velocimetry (stereo-PIV). The surface of the cornea was detected based on the images of laser-induced fluorescent light emitted from fluorescent dye solution introduced in a posterior chamber. A coaxial phacoemulsification procedure was simulated with standard size (standard coaxial phacoemulsification) and smaller (micro coaxial phacoemulsification) surgical instruments. In both cases, an asymmetric flow rate of irrigation was observed, although both irrigation ports had the same dimensions prior to insertion into the eye. In cases where the tip of the handpiece was placed farther away from the top of the cornea, i.e., closer to the crystalline lens, direct impingement of irrigation flow onto the cornea surface was avoided and the flow turned back toward the handpiece along the surface of the corneal endothelium. Viscous shear stress on the corneal endothelium was computed based on the measured mean velocity distribution. The maximum shear stress for most cases exceeded 0.1 Pa, which is comparable to the shear stress that caused detachment of the corneal endothelial cells reported by Kaji et al. in Cornea 24:S55–S58, (2005). When direct impingement of the irrigation flow was avoided, the shear stress was reduced considerably.

Factors influencing corneal biomechanical changes after microincision cataract surgery and standard coaxial phacoemulsification

To determine the factors affecting corneal biomechanics using biomechanical waveform analysis after microincision cataract surgery (MICS) and standard coaxial phacoemulsification with different incision sizes. Vissum-Instituto Oftalmologico de Alicante, Alicante, Spain. This prospective nonrandomized study comprised eyes with significant cataract that had MICS (sub-1.8 mm incision) or coaxial phacoemulsification (2.75 mm incision). Corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured by biomechanical waveform analysis (Ocular Response Analyzer) preoperatively, immediately postoperatively, and at 1 month. Results were analyzed and compared between groups. In the MICS group (n = 30), there was a significant increase in Goldmann-correlated intraocular pressure (IOP) and corneal-compensated IOP, although CH decreased in the immediate postoperative period (P<.05). At 1 month, all parameters in the MICS group returned to normal. The coaxial group (n = 30) had an increase in Goldmann-correlated IOP and corneal-compensated IOP, both of which were higher than normal at 1 month. Backward multiple regression analysis showed significant correlations between CH and preoperative Goldmann-correlated IOP and preoperative CRF (r(2) = 0.631, P<.05); between age, axial length (AL), and preoperative CRF (r(2) = 0.418, P<.05); and between the change in CH and AL, total incision length, and preoperative CH (r(2) = 0.429, P<.05). Cataract surgery with MICS and coaxial phacoemulsification significantly altered corneal biomechanics. Corneal hysteresis was inversely correlated with Goldmann-correlated IOP; CRF was inversely correlated with age and AL. The MICS technique provided more stable corneal biomechanical properties than standard coaxial phacoemulsification 1 month postoperatively.

Corneal Wound Architecture and Integrity After Torsional and Mixed Phacoemulsification: Evaluation of Standard and Microincisional Coaxial Techniques

To compare the effects of torsional and mixed ultrasound on clear corneal incision architecture, wound integrity, and apposition using standard (2.75 mm) and microincisional (2.2 mm) coaxial phacoemulsification. Twenty human cadaver eyes (4 groups of 5 eyes) underwent simulated coaxial phacoemulsification for 45 seconds of ultrasound time (group 1 = 2.75 mm, 100% torsional; group 2 = 2.2 mm, 70% torsional; group 3 = 2.2 mm, 100% torsional; group 4 = 2.2 mm, mixed ultrasound). All phacoemulsification settings were kept constant across each group. Following phacoemulsification, intraocular pressure (IOP) was cyclically raised and lowered from 0 to 125 mm Hg. Two eyes from each group had India ink placed over the wound and were observed for leakage and for histopathologic examination. Eyes not exposed to India ink (three eyes of each group) were examined using anterior segment optical coherence tomography (OCT) and scanning electron microscopy (SEM). Wound leakage was evident in one eye from group 1 and no eyes from the other three groups. Histopathologic examination revealed no India ink penetration in any of the eyes studied. Anterior segment OCT showed good wound apposition in each group. SEM demonstrated partially compromised endothelium and Descemet's membrane in all eyes studied from each group. No differences in corneal wound architecture and integrity were observed. Torsional and mixed ultrasound settings do not appear to induce any adverse effects on corneal wound architecture and integrity in standard and microincisional coaxial phacoemulsification techniques.

Uncorrected visual acuity in the immediate postoperative period following uncomplicated cataract surgery: bimanual microincision cataract surgery versus standard coaxial phacoemulsification

We compared bimanual microincision cataract surgery (MICS) and standard coaxial phacoemulsification (CAP) in terms of uncorrected visual acuity (UCVA) recorded 1 h and 2 weeks postoperatively. This was a prospective, nonrandomised comparative study. All MICS procedures were performed by one surgeon (MGM), and all CAP procedures were performed by another surgeon (SB). Eyes with visually consequential ocular morbidity were excluded. The primary outcome measure was UCVA recorded 1 h postoperatively. One hundred eyes underwent MICS and CAP (50 eyes in each group). The treatment groups did not differ significantly in terms of preoperative mean best corrected visual acuity (6/24 +/- 4.3 lines and 6/20 +/- 4.4 lines in the MICS and the CAP groups, respectively; P = 0.65). Also, there was no significant difference in terms of postoperative UCVA at 1 h or at 2 weeks (mean +/- standard deviation UCVA 1 h postoperatively: MICS: 6/36 +/- 5.7 lines; CAP: 6/30 +/- 4.7 lines; P = 0.80; UCVA 2 weeks postoperatively: MICS: 6/10 +/- 1.9 lines; CAP: 6/10 +/- 2.2 lines; P = 0.90). However, nine eyes (18%) and one eye (2%) achieved a UCVA of C6/12 at 1 h following MICS and CAP, respectively, and this difference was statistically significant (P = 0.02). Mean UCVA at 1 h and at 2 weeks following cataract surgery was not significantly different between eyes undergoing MICS and CAP. However, a greater proportion of patients achieved a UCVA of C6/12 following MICS when compared with CAP.

Corneal wound architecture and integrity after phacoemulsification: Evaluation of coaxial, microincision coaxial, and microincision bimanual techniques

To compare the effects of microincision bimanual phacoemulsification, standard coaxial phacoemulsification, and microincision coaxial phacoemulsification on clear corneal incision architecture and wound integrity.Department of Ophthalmology, Duke University, Durham, North Carolina, USA.A prospective study of 15 human cadaver eyes (3 groups of 5 eyes) ranging 1 to 4 days postmortem had simulated phacoemulsification by bimanual phacoemulsification (1.2 mm incision), standard coaxial phacoemulsification (2.75 mm), or microincision coaxial phacoemulsification (2.2 mm). All phacoemulsification settings were kept constant across each group. After phacoemulsification, intraocular pressure (IOP) was cyclically raised and lowered from 0 to 125 mm Hg. Two eyes in each group had India ink placed above the wound, and the IOP was varied as above. Entry of India ink into the wound or aqueous leakage from the wound was recorded. The same 2 corneas in each group were removed for histopathologic review of India ink penetration. Scanning electron microscopy was used to evaluate wound architecture in 1 eye in each group.Spontaneous wound leakage was evident in all 5 eyes having bimanual phacoemulsification, in 1 eye (20%) having standard coaxial phacoemulsification, and no eye having microincision coaxial phacoemulsification. India ink penetration was grossly evident in 2 of 2 eyes having bimanual phacoemulsification, 1 of 2 eyes having standard coaxial phacoemulsification, and neither of the 2 eyes having microincision coaxial phacoemulsification. Scanning electron microscopy showed increased endothelial cell loss and greater compromise to Descemet's membrane with bimanual phacoemulsification than with standard coaxial phacoemulsification or microincision coaxial phacoemulsification.Results in this experimental setting suggest microincision coaxial phacoemulsification and standard coaxial phacoemulsification induce less wound stress and alteration of wound morphology leading to wound leakage than microincision bimanual phacoemulsification.

Clear corneal incision leakage after phacoemulsification––detection using povidone iodine 5%

The purpose of this work was to study the incidence of clear corneal wound leakage at the conclusion of standard co-axial phacoemulsification in a prospective observational series of 100 consecutive cataract cases in a single surgeon's institutional practice. At the conclusion of standard co-axial phacoemulsification using a 2.75 mm temporal single plane clear corneal incision with a 1 mm clear corneal side-port incision, the wounds were hydrated and checked for water-tightness. Povidone iodine 5% (P-I) was then evenly dripped over the cornea and the wounds were inspected visually. Any leakage of aqueous observed was recorded. The amount of leakage was graded as small or large from each wound. Leaky wounds were further hydrated and retested with P-I until sealed. Wound integrity was reassessed on the first postoperative day by use of fluorescein. Of the 100 cases, wound leakage was observed for 31 eyes (31%)-ten main incisions, nineteen side-port incisions, and both incisions in two cases. Wound leakage was easily detected as a ribbon of clear fluid streaming from the incision amid a pool of brown solution. Povidone iodine was not observed within the tract in any incision. All wound leakage was small except for one from the main incision and two from the side-port incision. None of the eyes developed wound leakage the day after surgery and none developed endophthalmitis. In conclusion, leakage from clear corneal incisions at the conclusion of phacoemulsification occurs in almost a third of cases, predominantly from the side incision. It is easily detected by use of the P-I test.

Intraocular pressure during phacoemulsification

To assess changes in intraocular pressure (IOP) during standard coaxial or bimanual microincision phacoemulsification. Oregon Eye Center, Eugene, Oregon, USA. Bimanual microincision phacoemulsification (microphaco) was performed in 3 cadaver eyes, and standard coaxial phacoemulsification was performed in 1 cadaver eye. A pressure transducer placed in the vitreous cavity recorded IOP at 100 readings per second. The phacoemulsification procedure was broken down into 8 stages, and mean IOP was calculated across each stage. Intraocular pressure was measured during bimanual microphaco through 2 different incision sizes and with and without the Cruise Control (Staar Surgical) connected to the aspiration line. Intraocular pressure exceeded 60 mm Hg (retinal perfusion pressure) during both standard coaxial and bimanual microphaco procedures. The highest IOP occurred during hydrodissection, ophthalmic viscosurgical device injection, and intraocular lens insertion. For the 8 stages of the phacoemulsification procedure delineated in this study, IOP was lower for at least 1 of the bimanual microphaco eyes compared with the standard coaxial phaco eye in 4 of the stages (hydro steps, nuclear disassembly, irritation/aspiration, anterior chamber reformation). There was no consistent difference in IOP between the bimanual microphaco eyes and the eye that had standard coaxial phacoemulsification. Bimanual microincision phacoemulsification appears to be as safe as standard small incision phacoemulsification with regard to IOP.