Endothelial cell loss after phacoemulsification and insertion of silicone lens implants

Phacoemulsification and IOL-Implantation without Using Viscoelastics: Combined Modeling of Thermo Fluid Dynamics, Clinical Outcomes, and Endothelial Cell Density

Phacoemulsification is a widely used surgical method in cataract surgery with a high energy ultrasound source. The viscoelastic is considered to be tissue protective. The aim of this study is to investigate during surgery the impact of using viscoelastic versus no viscoelastic on clinical outcomes, potential complications and effect on endothelial cell density. The study group included 64 patients, who were subjected to phacoemulsification using balanced salt solution (BSS). Control group consisted of 62 patients, who underwent phacoemulsification using Hyaloronic acid 1% Healon 1%. Student’s t-test was applied for statistical analysis. The simulations of temperature changes during phacoemulsification were performed by COMSOL Multiphysics software. In the BSS group, a mean endothelial cell loss (ECL) of 4.5% was measured one month postoperatively, while in the Healon group ECL was 5.3%. Data analysis showed no significant difference in ECL between the groups (Student’s t-test, p = 0.8). No significant difference was observed in endothelial cell morphology and IOP between the two groups pre- and postoperatively (all p > 0.05). The modeling of thermo fluid dynamics showed that the heating of the cornea is slightly less when Healon was used as irrigation fluid. The phacoemulsification technique can be performed by an experienced surgeon with viscoelastics or continuous anterior chamber (AC) irrigation on the same level of safety regarding endothelial cell damage, providing equally satisfying clinical outcomes.

Protective effect of free-radical scavengers on corneal endothelial damage in phacoemulsification

PURPOSE

To examine the role of the water-soluble antioxidants glutathione and ascorbic acid in the irrigating solution on corneal endothelial cells following exposure to high-intensity ultrasound energy.

SETTING

Goldschleger Eye Research Institute, Sheba Medical Center, Tel-Aviv University, Tel Aviv, Israel.

METHODS

Thirty-two rabbit eyes were subjected to prolonged exposure to the phacoemulsification device in the anterior chamber. The eyes were divided into 4 groups that differed only in the composition of the irrigating solution applied to the eyes: balanced salt solution (BSS) BSS Plus BSS containing additional soluble components including glutathione, BSS with 10(-3) M of oxidized glutathione (GSSG), and BSS with 10(-2) M of ascorbic acid. Specular microscopy was performed preoperatively and 1 week after surgery.

RESULTS

The BSS group exhibited the highest endothelial cell loss (19.3%), followed by the BSS Plus group (10.6%), the GSSG group (5.2%), and the ascorbic acid group (0.9%). An overall difference was found between the groups (F = 11.046, P<.0001), and all groups demonstrated a statistically significant difference from the control BSS group (P<.02, P = .001, and P<.0001, respectively).

CONCLUSIONS

Damage to the cornea is largely due to the free radicals generated by high-intensity ultrasound energy during phacoemulsification. Adding the antioxidants ascorbic acid and GSSG to the irrigation solution significantly reduced the endothelial corneal cell damage. Ascorbic acid in the concentration of 10(-2) M had the highest protective effect; thus, it should be evaluated for clinical use.

Endothelial cell density after posterior lamellar keratoplasty (Melles techniques): 3 years follow-up

PURPOSE

To report the midterm endothelial cell density measurements after posterior lamellar keratoplasty (Melles techniques).

DESIGN

Cohort study.

METHODS

Fifteen consecutive eyes of 15 patients in whom a posterior lamellar keratoplasty procedure was performed for pseudophakic bullous keratopathy or Fuchs' endothelial dystrophy were evaluated. In 11 corneas the donor tissue was inserted through a 9.0-mm sclerocorneal pocket incision (technique A); in four cases the donor was folded and inserted through a 5.0-mm incision (technique B). Specular microscopy was performed at 6, 12, 24, and 36 months after surgery, to measure the endothelial cell density.

RESULTS

Mean postoperative endothelial cell density averaged 2,126 cells/mm(2) (+/-548) at 6 months, 1,859 cells/mm(2) (+/-477) at 12 months, 1,385 cells/mm(2) (+/-451) at 24 months, and 1,047 cells/mm(2) (+/-425) at 36 months.

CONCLUSION

In posterior lamellar keratoplasty, the donor corneal endothelium showed a decrease in cell density similar to that after conventional full-thickness penetrating keratoplasty.

Effect of incision size and site on corneal endothelial changes in cataract surgery

PURPOSE

To compare endothelial damage induced by different cataract incision sites and sizes using specular microscopy.

SETTING

Department of Ophthalmology, Hospital of San Donà di Piave, Venice, Italy.

METHODS

Eighty-one eyes having phacoemulsification were randomly assigned to 1 of 3 groups of 27 eyes each: 3.5 mm clear corneal incision (CCI) with silicone foldable intraocular lens (IOL) implantation; 5.5 mm sutured CCI with poly(methyl methacrylate) (PMMA) IOL implantation; 5.5 mm scleral tunnel with PMMA IOL implantation. All incisions were centered at the 120-degree semimeridian; that is, they were superotemporal in right eyes and superonasal in left eyes. Noncontact specular microscopy was performed in the center and at the 12 o'clock position preoperatively as well as 1 week and 1, 3, and 12 months postoperatively. The endothelial cell density, mean cell area, cell size variation coefficient, percentage of hexagonality, and corneal thickness were considered.

RESULTS

Progressive endothelial cell loss and an increase in mean cell area occurred in all groups during the follow-up. The cell loss percentages relative to the endothelial center appeared similar among the groups and slightly although not significantly lower in the scleral tunnel group. The scleral tunnel group had a statistically significant lower cell loss percentage at the 12 o'clock position than the 2 CCI groups at all follow-ups.

CONCLUSIONS

The scleral tunnel group had less postoperative endothelial damage than the 2 CCI groups, with a statistically significant difference at the 12 o'clock position. This is probably because the scleral tunnel incision is placed more posteriorly and therefore induces less direct and indirect endothelial trauma.

Effects of intraocular cefotaxime on the human corneal endothelium

PURPOSE

To ascertain whether 0.4 mL of cefotaxime 0.25% applied intracamerally causes toxic alteration of the human corneal endothelium.

METHODS

In this prospective randomized masked study, 66 patients had cataract extraction using phacoemulsification, a frown incision, and implantation of a poly(methyl methacrylate) intraocular lens. This was followed by intraocular injection of 0.4 mL of cefotaxime 0.25% or balanced salt solution (BSS(R)). Contact specular microscopy and photography were performed preoperatively and 1 to 4 days and 3 months postoperatively.

RESULTS

In the cefotaxime group, the mean endothelial cell count was 2729 cells/mm(2) +/- 474 (SD) preoperatively, 2520 +/- 462 cells/mm(2) 1 to 4 days postoperatively, and 2560 +/- 495 cells/mm(2) 3 months postoperatively. The mean endothelial cell count in the BSS (control) group was 2657 +/- 413 cells/mm(2), 2475 +/- 384 cells/mm(2), and 2486 +/- 427 cells/mm(2), respectively. There was no significant difference in cell count or morphology between groups (P <.05).

CONCLUSIONS

Intraocular application of cefotaxime produced no significant changes in endothelial cell count or morphology when compared with application of a control substance. With its broad spectrum of antibiotic activity, cefotaxime might be an appropriate alternative to other intraocularly administered antibiotics in anterior segment surgery for prophylaxis and management of infection.

Double-masked prospective ocular safety study of a lens epithelial cell antibody to prevent posterior capsule opacification

PURPOSE

To evaluate the intraocular safety of an immunoconjugate (MDX-RA) developed to prevent posterior capsule opacification (PCO) in human eyes.

SETTING

St. Thomas's Hospital Eye Department, London, United Kingdom.

METHODS

Twenty-six patients had phacoemulsification and implantation of an intraocular lens (IOL). All were randomly allocated at the end of surgery to receive a 0.1 mL placebo or 0.1 mL of the immunotoxin MDX-RA intracamerally. Two doses of the drug were tested: 8 patients with a low dose (50 units), 9 patients with a high dose (100 units), and 9 with placebo. Follow-up at days 1, 14, 30, 60, 90, and 180 consisted of visual acuity measured by the Early Treatment of Diabetic Retinopathy Study test, contrast sensitivity, aqueous flare, specular microscopy of the IOL's anterior surface, and corneal endothelial counts. The percentage area of PCO was measured from retroillumination images of the posterior capsule.

RESULTS

There was no decrease in corneal endothelial cell count in toxin-treated patients. Early postoperative flare, anterior chamber cell count, and corneal pachymetry were higher in toxin-treated patients. The median percentage area of PCO at 1 year was 32.0 in the placebo group, 3.8 in the low-dose group, and 7.4 in the high-dose group (P = .06).

CONCLUSION

This prospective, randomized, placebo-controlled trial confirmed that MDX-RA is safe for intraocular use and is of potential value for further clinical trials of the prevention of PCO.

Irreversible corneal decompensation in patients treated with topical dorzolamide

PURPOSE

To describe irreversible corneal decompensation after topical dorzolamide hydrochloride (Trusopt; Merck and Co, Inc, West Point, Pennsylvania) therapy in nine patients who had histories consistent with corneal endothelial compromise.

METHOD

Multicenter review of patients' charts.

RESULTS

Nine eyes of nine patients developed overt corneal decompensation after starting topical dorzolamide, a condition that did not resolve with drug cessation. This occurred after 3 to 20 weeks (mean, 7.8) of therapy. All nine patients had undergone intraocular surgery. Eight patients had undergone cataract surgery; three were aphakic and three had posterior chamber intraocular lenses. Two patients had anterior chamber intraocular lenses and also had undergone trabeculectomies. Four patients had undergone penetrating keratoplasties, each case complicated by episodes of corneal allograft rejection that were successfully treated. Two patients had asymptomatic Fuchs endothelial dystrophy. Seven patients have since undergone successful penetrating keratoplasties.

CONCLUSION

The reports suggest that dorzolamide can cause irreversible corneal edema in a subset of glaucoma patients with endothelial compromise. The findings suggest a rationale for research into the long-term effects of dorzolamide on the corneal endothelium.

Corneal endothelial changes after divide and conquer versus chip and flip phacoemulsification

PURPOSE

To evaluate changes in central corneal endothelial cells and corneal thickness after divide and conquer phacoemulsification and chip and flip phacoemulsification.

SETTING

Houston Eye Clinic, Houston, Texas, USA.

METHODS

Forty-four eyes were randomly assigned to one of two groups to have divide and conquer (D/C Group) or chip and flip (C/F Group) phacoemulsification with implantation of a posterior chamber, foldable, silicone intraocular lens performed by one surgeon. Of these, 41 eyes of 37 patients (22 D/C Group, 19 C/F Group) met the inclusion criteria. All surgeries were uneventful. A complete eye examination including specular microscopy and pachymetry was performed preoperatively and 1 week and 1 and 3 months postoperatively.

RESULTS

There were no significant between-group differences in any of the following means: sex; age; time at 70% phaco power; total phacoemulsification time. No correlation was found between ultrasound time and increased corneal thickness except for a significant increase in percentage of hexagonal cells in the C/F Group at 1 month. The only statistically significant between-group differences were greater endothelial cell loss in the C/F Group at 1 month and the percentage change in hexagonal cells at 1 week (1.1% increase, D/C Group; 10.7% decrease, C/F Group).

CONCLUSION

The divide and conquer technique led to less endothelial loss and hexagonal cell change than the chip and flip technique, although at 3 months the differences were not significant.

Corneal endothelial cell loss in phacoemulsification surgery with silicone intraocular lens implantation

PURPOSE

To clarify the extent of corneal endothelial injury from silicone intraocular lens (IOL) implantation in small incision cataract surgery.

METHODS

Two hundred forty eyes that had phacoemulsification surgery were divided into four groups: Group A comprised 70 eyes that received a conventional silicone IOL; Group B, 63 eyes that received a higher refractive index silicone IOL; Group C, 71 eyes that received a poly(methyl methacrylate) (PMMA) IOL; Group D, 36 eyes that had phacoemulsification without an IOL. Cell density of the corneal endothelium in all eyes was examined by specular microscopy preoperatively and 3 months postoperatively, and the percentage of endothelial cell loss was determined. The differences in endothelial cell loss between the four groups were statistically compared using the Kruskal-Wallis test.

RESULTS

Percentages of endothelial cell loss were 4.5 +/- 5.1% in Group A, 4.3 +/- 5.3% in Group B, 6.3 +/- 5.4% in Group C, and 4.3 +/- 4.9% in Group D. No statistically significant difference was observed among these four groups, although the percentage of cell loss in Group C was slightly larger than that in the other groups.

CONCLUSION

The implantation of silicone IOLs and PMMA IOLs causes minimal corneal endothelial cell loss in contemporary small incision surgery.

Comparison of the induced astigmatism after temporal clear corneal tunnel incisions of different sizes

A prospective, randomized study compared the surgically induced astigmatism after 3.5 mm, 4.0 mm, and 5.0 mm temporal corneal tunnel incisions over six months. We studied 60 eyes of 60 patients who had phacoemulsification through a two-step clear corneal tunnel incision and implantation of one of three posterior chamber intraocular lenses (IOLs). Patients were divided into three groups of 20 each: Group A, cartridge injection of a foldable plate-haptic silicone IOL through a 3.5 mm self-sealing incision; Group B, cartridge injection of a disc silicone IOL through a 4.0 mm self-sealing incision; Group C, 5.0 mm optic poly(methyl methacrylate) IOL through a 5.0 mm incision with one radial suture. Corneal topography data were obtained using a computerized videokeratographic analysis system preoperatively and one week and six months postoperatively. Vector analysis was performed to calculate the surgically induced astigmatism. After the first postoperative week, mean induced astigmatism was 0.63 diopters (D) (+/- 0.41) in Group A, 0.64 D (+/- 0.35) in Group B, and 0.91 D (+/- 0.77) in Group C. After six months, it was 0.37 D (+/- 0.14) in Group A, 0.56 D (+/- 0.34) in Group B, and 0.70 D (+/- 0.50) in Group C. Surgically induced astigmatism was significantly lower in Group A than in Group B (P < .05) and Group C (P < .005) after six months. Vector analysis demonstrated that temporal corneal tunnel incisions induced clinically minimal astigmatism over six months postoperatively depending on incision size.

Visual acuity recovery rates following cataract surgery and implantation of soft intraocular lenses

To determine whether eyes receiving soft optic lens implants had faster visual recovery times than eyes receiving firm optic lens implants, we calculated the visual acuity recovery rates following our standard cataract operation. Visual acuity of 20/50 or better without correction was obtained in 31% of eyes on the first day following surgery, 55% at one week, 74% at three weeks, and 89% at six weeks and three months. Fifty best-case soft optic lens implant cases were reviewed and their visual recovery rates were calculated. There were no statistically significant differences in the visual acuities without correction at any follow-up point. There was a slightly significant difference at one week with correction and a significant difference at three weeks with correction favoring the soft lens/small incision group. Because optical correction is generally not provided on these visits, we conclude that soft lens implants with small incisions did not provide clinically significant improvement in visual acuity recovery over our standard cataract procedure.

Keratometric cylinder and visual performance following phacoemulsification and implantation with silicone small-incision or poly(methyl methacrylate) intraocular lenses

Silicone and poly(methyl methacrylate) (PMMA) intraocular lenses from Allergan Medical Optics were implanted in the posterior chamber of 96 cataract patients with small or standard incisions following phacoemulsification. Significantly less keratometric cylinder (astigmatism) and better uncorrected visual acuity were observed during the six week postsurgical follow-up in the patients who received the small incision silicone lens than in those who received the standard PMMA lens.