Healon GV in extracapsular cataract extraction with intraocular lens implantation

Oral versus topical carbonic anhydrase inhibitors in ocular hypertension after scleral tunnel cataract surgery

Purpose:

To compare the effect of oral acetazolamide and topical 2% dorzolamide in prevention of ocular hypertension after scleral tunnel cataract surgery.

Setting:

Ophthalmic department, Sana’a University, Yemen Sana’a from March 2007 to October 2007.

Methods:

This prospective double-blind, randomized study included 150 eyes undergoing scleral tunnel cataract surgery with hard posterior chamber intraocular implantation. Methylcellulose was used as the viscoelastic in all surgery cases. Patients were assigned to one of three groups: group 1: topical gentamicin eye drops (control; n = 52); group 2: systemic acetazolamide 250 mg (n = 45); and group 3: topical 2% dorzolamide (n = 53). Acetazolamide patients received one 250 mg tablet, one hour before surgery, then half a tablet every eight hours. A topical dorzolamide 2% or gentamicin was applied in one drop one hour before surgery then every eight hours, for three days postoperatively. Intraocular pressures (IOP) were measured by Goldman applanation tonometry one hour preoperatively and 16, 24, and 48 hours postoperatively.

Results:

At 16 hours, IOP between the three groups increased significantly with a statistically significant p-value of 0.008, but the mean IOP of acetazolamide patients was less than other groups. IOP nearly returned to the normal level 24 and 48 hours postoperatively, but this was not statistically significant (p = 0.452 and 0.138, respectively).

Conclusion:

Acetazolamide offers better IOP control than topical dorzolamide 2% in preventing ocular hypertension after scleral tunnel cataract surgery.

Corneal endothelial cell protection with a dispersive viscoelastic material and an irrigating solution during phacoemulsification: low-cost versus expensive combination

PURPOSE

To evaluate the protective effect on corneal endothelial cells of a low-cost and an expensive combination of a dispersive viscoelastic material and an irrigating solution during phacoemulsification.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective randomized examiner- and patient-masked study comprised 90 eyes of 45 consecutive patients with age-related cataract in both eyes. For each patient, the first eye was randomly assigned to receive hydroxypropyl methylcellulose 2% (Ocucoat) and Ringer's solution (low-cost combination) or sodium chondroitin sulfate 4%-sodium hyaluronate 3% (Viscoat) and an enriched balanced salt solution (BSS Plus) (expensive combination) during phacoemulsification. The contralateral eye received the other treatment. Endothelial cell function was evaluated by measuring corneal thickness (CT) using partial coherence interferometry, morphology assessment, and endothelial cell counts.

RESULTS

The acute postoperative increase in CT was +9.8 microm in the low-cost group and +10.9 microm in the expensive group; the difference between groups was not significant. After 1 month, the CT still differed significantly from baseline in the low-cost group. Three months after surgery, the CT had returned to baseline values in both groups. There was no significant between-group difference in endothelial cell counts or morphology.

CONCLUSIONS

During phacoemulsification in a nonselected patient population, there was no difference in acute postoperative corneal edema and endothelial cell morphology after 3 months between a Viscoat and BSS Plus combination and an Ocucoat and Ringer's solution combination. Eyes receiving the expensive combination had marginally faster recovery of corneal swelling by 3 months. However, the cost of Viscoat and 500 mL BSS Plus is 5 times that of Ocucoat and Ringer's solution.

Comparison of the clinical performance of Healon 5 and Healon in phacoemulsification

PURPOSE

Healon 5 is a high-molecular-mass fraction of sodium hyaluronate. Its density endows it with a number of viscoelastic characteristics. In this prospective, randomised clinical study we compared the performance of Healon 5 and Healon in phacoemulsification.

SETTING

Institute of Ophthalmology, University of Modena and Reggio Emilia, Italy.

METHODS

Two groups of patients underwent phacoemulsification and intraocular lens (IOL) implantation. In the first 27 patients Healon 5 was used as viscoelastic substance during surgery, and in the second 27 Healon was used. The surgeons subjective comments on the performance of these viscoelastic agents were recorded at the different steps of surgery: injection, capsulorhexis, phacoemulsification, IOL implantation, removal of viscoelastic agent and trasparency throughout the operation. The surgeon's overall impression of the viscoelastics during the whole operation was noted. Tonometry and endothelial cell count were performed in all patients before and after operation.

RESULTS

There was no statistical difference between the two groups as regards visual acuity, ocular pressure and endothelial damage. Healon 5 showed excellent ability to maintain the anterior chamber during capsulorhexis, phacoemulsification and IOL implantation. Removal time with Healon 5 was not appreciably longer than Healon.

CONCLUSIONS

Healon 5 emerges as a very interesting viscoelastic substance. Visibility is better if the anterior chamber is filled completely. Removal is easier if it is aspirated while moving the irrigation aspiration tip with circular movements over the top and around the border of the IOL.

Corneal thickness and visual acuity after phacoemulsification with 3 viscoelastic materials

PURPOSE

To determine whether differences exist in visual acuity and corneal thickness after phacoemulsification using various viscoelastic substances.

SETTING

Phillips Eye Institute, Minneapolis, Minnesota, USA.

METHODS

Fifty patients having routine phacoemulsification cataract extraction and intraocular lens implantation by a single surgeon using the same technique were randomly assigned to receive intraoperative administration of 1 of 3 viscoelastic substances: Amvisc Plus(R) (sodium hyaluronate 1.6%), OcuCoat(R) (hydroxypropyl methylcellulose 2%), or Viscoat(R) (chondroitin sulfate 4%-sodium hyaluronate 3%). Visual acuity and corneal thickness on the first postoperative day were compared between groups.

RESULTS

Patients with a best corrected visual acuity (BCVA) of 20/40 or better 1 day postoperatively had significantly thinner corneas (596 microm) than those with a BCVA worse than 20/40 (639 microm). There were no differences in postoperative BCVA or percentage increase in central corneal pachymetry among the 3 viscoelastic groups.

CONCLUSION

Viscoat, Amvisc Plus, and OcuCoat were comparable in their ability to produce clear corneas and good vision after routine phacoemulsification.

Intraocular pressure after small incision cataract surgery with Healon5 and Viscoat

PURPOSE

To evaluate the effect of Healon5 (sodium hyaluronate) and Viscoat (sodium chondroitin sulfate-sodium hyaluronate) on intraocular pressure (IOP) after bilateral small incision cataract surgery.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective randomized study comprised 70 eyes of 35 consecutive patients with age-related cataract in both eyes scheduled for bilateral small incision cataract surgery. The patients were randomly assigned to receive Healon5 or Viscoat during cataract surgery in the first eye. The second eye received the other viscoelastic substance. Cataract surgery was performed in an identical fashion in both eyes, with a temporal 3.5 mm sutureless posterior limbal incision, phacoemulsification, and implantation of a foldable silicone intraocular lens. The IOP was measured preoperatively and 6 hours, 20 to 24 hours, and 1 week postoperatively.

RESULTS

At 6 hours after surgery, the mean IOP increased by 5.2 mm Hg +/- 5.3 (SD) in the Healon5 group (P < .0001) and by 10.1 +/- 8.7 mm Hg in the Viscoat group (P < .0001). The increase was significantly higher in the Viscoat group than in the Healon5 group (P = .0016). Intraocular pressure spikes of 30 mm Hg or more occurred in 2 eyes in the Healon5 group and in 10 eyes in the Viscoat group (P = .0112). Twenty to 24 hours and 1 week postoperatively, the mean IOP in the 2 groups was not statistically different.

CONCLUSIONS

Viscoat caused a significantly higher IOP increase and significantly more IOP spikes than Healon5 in the early period after small incision cataract surgery.

Comparison of the effects of viscoelastic agents on clinical properties of the Unfolder lens injection system

PURPOSE

To evaluate the effect of 7 viscoelastic materials on the physical properties of the Unfolder lens injection system.

SETTING

John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA.

METHODS

New sterile SI-40NB intraocular lenses (IOLs) were loaded into the Unfolder (AMO PhacoFlex II SofTip insertion system (Allergan) using 7 viscoelastic materials: sodium hyaluronate 1.0% (Healon, Provisc), sodium hyaluronate 1.4% (Healon GV), sodium hyaluronate 1.6% (Amvisc Plus), hydroxypropyl methylcellulose 2.0% (Occucoat), sodium chondroitin 4.0%--sodium hyaluronate 3.0% (Viscoat), and hyaluronate 3.0% (Vitrax). The IOLs were then injected after 10 or 120 seconds in the chamber (chamber dwell time) and 10, 60, or 180 seconds in the barrel of the Unfolder cartridge (barrel dwell time). Torque values (g/cm) required to extrude the lenses were measured with a torque gauge, and the cartridges and IOLs were inspected for damage.

RESULTS

Longer chamber dwell times resulted in lower torque values to extrude the IOLs (P < .001). Conversely, longer barrel dwell times resulted in higher torque requirements for IOL extrusion (P < .001). Furthermore, rates of adverse events, such as nondelivery, IOL damage, or Unfolder cartridge damage, were higher with shorter chamber dwell times and longer barrel dwell times (P < .001). However, IOL damage was avoided when the manufacturer's recommended chamber and barrel times were used.

CONCLUSION

Increasing chamber dwell time and decreasing barrel dwell time resulted in lower torque values to extrude IOLs from the Unfolder and increased successful use. Moreover, dispersive viscoelastic agents tended to be more forgiving of changing dwell times and therefore had lower torque values and adverse event rates overall.

Manual nucleofragmentation and endothelial cell loss

PURPOSE

To compare corneal endothelial cell loss with two cataract surgery techniques: manual nucleofragmentation performed with the Keener nucleus divider and planned extracapsular extraction.

SETTING

Department of Ophthalmology "Memorial Cristóbal Garrigosa," Hospital de l'Esperança, Universitat Autònoma de Barcelona, Spain.

METHODS

Contact specular microscopy was performed before and 8 weeks after surgery in 51 patients who had been prospectively randomized into 2 groups: 26 patients had manual nucleofragmentation (NF) with the Keener divider and 25, planned extracapsular cataract extraction (ECCE). The analyzed parameters were preoperative and postoperative endothelial cell density and variations in cell size (polymegethism) and cell shape (pleomorphism). The results were compared and statistically analyzed.

RESULTS

The mean percentage of endothelial cell loss in the NF group was 11.08% and in the ECCE group, 9.86%. This difference was not statistically significant. Postoperative variation in cell shape and size did not differ significantly between the two groups and was fairly constant.

CONCLUSION

The percentage of endothelial cell loss that occurred with manual NF using the Keener nucleus divider was similar to the one that occurs with other cataract surgery techniques. The small variation detected in postoperative endothelial morphology suggests that this endothelial cell population is stable.

Corneal endothelial protection by different viscoelastics during phacoemulsification

PURPOSE

To evaluate corneal endothelium morphology and function after phacoemulsification using different viscoelastics.

SETTING

Eye Clinic, University of Trieste, Italy.

METHODS

This prospective, randomized study included results of preoperative and postoperative (7, 30, and 90 days) examinations of 66 patients scheduled for phacoemulsification without ocular pathology; 8 patients were excluded. Patients were randomly assigned to one of four groups based on type of viscoelastic used: 1% sodium hyaluronate (Healon); 1.4% sodium hyaluronate (Healon GV); 4% sodium chondroitin sulfate-3% sodium hyaluronate (Viscoat); 2% hydroxypropyl methylcellulose (Hymecel). Mean cell density and cell size variation coefficient were determined by specular microscopy; central corneal thickness, by ultrasonic pachymetry; and endothelial permeability coefficient and active pump function, by anterior segment fluorophotometry.

RESULTS

There were no significant differences in postoperative mean cell loss among the groups. The cell size variation coefficient was altered in all groups 7 days after surgery and was still impaired at 30 days in the Hymecel group. A significant increase in mean corneal thickness, endothelial permeability, and active pump function occurred in the Healon and Hymecel groups 7 days after surgery. These parameters were still altered 30 days after surgery in the Hymecel group. Endothelial functional alterations did not occur in the Healon GV or Viscoat group.

CONCLUSION

Viscoat and Healon GV are effective in minimizing functional damage of endothelial structure in the early medium-term postoperative period.

Comparison of viscoelastic substances used in phacoemulsification

PURPOSE

To evaluate the usefulness of four viscoelastic agents during phacoemulsification: 2% hydroxypropylmethylcellulose (HPMC) (Methocel), 3% sodium hyaluronate with 4% chondroitin sulfate (Viscoat), 1% sodium hyaluronate (Healon), 1.4% sodium hyaluronate (Healon GV).

SETTING

Eye Clinic, Kreiskrankenhaus Bad Hersfeld, Germany.

METHODS

Two hundred patients, divided into four groups of 50 patients, received one of the viscoelastic substances during phacoemulsification and posterior chamber intraocular lens implantation. Patients were followed for 1 month. Visual acuity and intraocular pressure (IOP) were measured. The following were subjectively evaluated for each viscoelastic: corneal findings, anterior chamber reaction, visibility of intraocular structures and retention time during phacoemulsification, space maintaining ability, and removability and ease of injection.

RESULTS

Postoperative IOP and visual acuity were comparable among the four groups. Viscoat tended to trap nuclear fragments and air bubbles during the phacoemulsification procedure, which decreased visibility during surgery. Space maintenance and injection ease were significantly better with Healon and Healon GV.

CONCLUSION

The high molecular weight viscoelastics (Healon and Healon GV) performed better as viscosurgical tool during cataract surgery using phacoemulsification.

Evaluation of intraocular pressure with Healon and Healon GV in sutureless cataract surgery with foldable lens implantation

PURPOSE

To evaluate transient increases in intraocular pressure (IOP) after use of high-viscosity viscoelastic agents in cataract surgery.

SETTING

Military Hospital, Ulm, Germany.

METHODS

In a prospective, randomized study, we evaluated IOP following cataract surgery using two different viscoelastic substances (Healon, Healon GV). The viscosity of Healon GV is 10 times higher than that of Healon because of higher concentration and molecular weight. Patients having identical phacoemulsification procedures (sutureless clear corneal tunnel incision with foldable silicone lens implantation) (N = 60) and identical viscoelastic removal were assigned to groups of 15 based on viscoelastic used and removal time (20 or 40 seconds). Intraocular pressure was measured preoperatively and at 6, 24, 36, and 48 hours and 1 month postoperatively.

RESULTS

The highest mean IOP elevations in both viscoelastic groups were obtained at 24 hours postoperatively (2.9 mm Hg +/- 4.3 [SD] with Healon and 3.3 +/- 6.3 mm Hg with Healon GV). There were no statistically significant differences between the two viscoelastics and the two removal times during the entire follow-up period (unpaired t-test), but standard deviations were higher in the Healon GV groups at 6 and 24 hours. Two patients in the Healon groups and three in the Healon GV groups required medical treatment for IOP within the first 24 postoperative hours; however, all five patients had an IOP lower than 22 mm Hg on the second postoperative day.

CONCLUSIONS

Based on postoperative IOP, both viscoelastics can be equally well removed from the anterior chamber. Incidence of high IOP using high-viscosity hyaluronic acid is minimized by the described removal technique.

Healon GV versus Healon in demanding cataract surgery

This study compared how well two sodium hyaluronate viscoelastics maintained the anterior chamber during cataract surgery in eyes at risk for high vitreous pressure. Patients were divided into two groups based on the sodium hyaluronate used: Healon or Healon GV. Qualitative data were obtained with a digital slide gauge attached to the operating microscope. After capsulorhexis, mean anterior chamber depth (distance of the corneal apex to the iris plane) was significantly greater in the Healon GV group (P = .0012). Subjective intraoperative evaluation by surgeons also favored Healon GV. There was no difference between the groups in postoperative inflammation, corneal edema, intraocular pressure, or visual acuity. Therefore, although the two viscoelastics are equally safe, Healon GV maintains the anterior chamber better during cataract surgery.

Comparison of endothelial cell loss and phacoemulsification energy during endocapsular phacoemulsification surgery

We counted central corneal endothelial cells and measured corneal thickness in 64 human eyes before and three months after cataract extraction and posterior chamber lens implantation. Cataract surgery was the same in all patients and included capsulorhexis and posterior chamber phacoemulsification of the nucleus. Total phacoemulsification energy and time were recorded. A heparin-surface-modified intraocular lens or a regular poly(methyl methacrylate) lens, both having the same design and a 5.0 mm optic, was implanted in the capsular bag with the aid of sodium hyaluronate (Healon). Mean endothelial cell loss was 4%. However, the change in cell density did not correlate with the total phacoemulsification energy used during surgery. Three months after surgery, the central corneal thickness was the same as it had been preoperatively. The results suggest that phacoemulsification in the posterior chamber is a safe procedure even in cases with a hard nucleus.

Viscoelastic-related glaucomas

The routine surgical use of viscoelastic substances has revolutionized many anterior segment procedures. All of the currently available agents may be responsible for causing or exacerbating a transient, but occasionally significant, postoperative IOP elevation. In spite of differences in physical properties such as molecular weight, concentration, and viscosity, none of the various viscoelastics has consistently shown a decreased likelihood of producing ocular hypertension. Moreover, any newly introduced product must be evaluated carefully for this potential complication. Lavage of viscomaterial from the anterior chamber and administration of ocular antihypertensives may be helpful in averting or controlling the increased IOP. The surgeon should be cognizant of any pre-existing optic nerve damage and adjust the aggressiveness of postoperative glaucoma therapy accordingly. In the future, the development of new substances or simultaneous use of degrading enzymes may reduce or eliminate the incidence of viscoelastic-induced ocular hypertension.