Intraocular irrigating solutions. A comparative study of BSS Plus and lactated Ringer's solution

Effects of a fortified balanced salt solution and Ringer's lactate solution on anterior chamber inflammation after phacoemulsification in diabetes

PURPOSE

To compare the effects of a fortified balanced salt solution (fSS) and Ringer's lactate solution (Ringer) on anterior chamber (AC) inflammation in patients undergoing phacoemulsification.

SETTING

Tianjin Medical University Eye Hospital, Tianjin, China.

DESIGN

Prospective masked controlled trial.

METHODS

80 patients (40 patients with regular cataract and 40 cataract patients with diabetes mellitus [DM]) were randomized to receive either fSS (n = 40) or Ringer's solution (n = 40). Anterior-segment optical coherence tomography was used to evaluate AC cells and flare. Transepithelial electrical resistance (TEER) and zonula occludens-1 (ZO-1) immunofluorescence were used for tight junction examination. Monocytic leukemia cell line (Tohoku Hospital Pediatrics-1 [THP-1]) transmigration assay was performed to observe the effects of the 2 perfusates on the inflammatory response in vitro.

RESULTS

In patients with regular cataracts, postoperative AC cells and flare on the 1st and 7th days were not significantly different between the Ringer and fSS groups. However, in cataract patients with DM, AC cells were higher in the Ringer group than in the fSS group ( P = .003) on postoperative day 1. The AC flare was also significantly higher in the Ringer group than in the fSS group ( P < .0001). No significant differences between the groups were observed on day 7. Compared with Ringer, fSS increased the TEER value and ZO-1 content and reduced the adhesion of THP-1 cells.

CONCLUSIONS

The results of this study indicated that early postoperative AC inflammation is more severe in patients with cataracts and DM. In addition, fSS attenuates inflammation by protecting the blood-aqueous barrier and inhibiting the exudation of inflammatory cells.

A Novel Small Peptide H-KI20 Inhibits Retinal Neovascularization Through the JNK/ATF2 Signaling Pathway

Purpose

Abundant evidence has shown benefits of antivascular endothelial growth factor (anti-VEGF) therapies in neovascular eye diseases. However, the high cost, side effects, and inconvenience of frequent injections demand alternative novel drug candidates. This study aimed to analyze antiangiogenic effects of peptide H-KI20 and illustrated signaling mechanisms.

Methods

Live cell culture and tracing, wound healing assay, and tube formation were performed in human retinal microvascular endothelial cells (HRECs). The chick embryo chorioallantoic membrane and mouse oxygen-induced ischemic retinopathy model were applied to examine the effects of H-KI20 in vivo. The intracellular signaling pathways were examined. Molecular docking and surface plasmon resonance assay were used to validate the direct interaction of H-KI20 and c-Jun N-terminal kinase 2 (JNK2).

Results

H-KI20 had high penetration ability in vitro and in vivo. It inhibited motility, migration, and tube formation of HRECs, without cytotoxicity, and inhibited angiogenesis in vivo. Furthermore, H-KI20 treatment reduced the phosphorylation level of activating transcription factor 2 (ATF2) stimulated by VEGF via downregulating p-JNK. H-KI20 bound to JNK2 directly with a dissociation constant value of 83.68 µM. The knockdown of ATF2 attenuated VEGF-induced tube formation and decreased the movement speed of HRECs.

Conclusions

H-KI20 inhibited angiogenesis both in vitro and in vivo. The ratios of p-ATF2/ATF2 and p-JNK/JNK stimulated by VEGF were decreased by H-KI20, and H-KI20 targeted JNK2 directly. In addition, the pivotal role of ATF2 in VEGF-induced retinal neovascularization was elucidated for the first time. Taken together, H-KI20 displays potential for pathological retinal angiogenesis as a sustained and low-toxic peptide.

Comparison of corneal changes after phacoemulsification using BSS Plus versus Lactated Ringer's irrigating solution: a prospective randomised trial

Background/aims

To compare two intraocular irrigating solutions, Balanced Salt Solution Plus (BSS Plus) versus Lactated Ringer's (Ringer), for the preservation of corneal integrity after phacoemulsification.

Methods

110 patients undergoing phacoemulsification were randomised to either BSS Plus (n=55) or Ringer (n=55) as the irrigating solution. Patients were examined at baseline and at 1, 8, 15, 30 and 60 days postoperatively. Evaluations included specular microscopy to evaluate endothelial cell density (ECD) and endothelial cell size variability (CV), and corneal pachymetry for central corneal thickness (CCT) measurement.

Results

Groups were well balanced regarding baseline ECD, CV and CCT (p>0.05). There was no statistically significant difference between ECD reduction in group BSS Plus 13.1±2.0% and Ringer 9.2±1.9% (p<0.05) at day 60 or in any study visit. There was no statistically significant difference between CV increase in group BSS Plus 23.0±3.0% and Ringer 20.2±4.0% (p<0.05) at day 60 or in any study visit. CCT was significantly increased (p<0.05) at 1, 8, 15 and 30 days postoperatively, returning to baseline at 60 days in both groups. There was no significant difference in CCT increase in both groups at any visit. Interestingly, there were statistically significant correlations between ECD loss and phacoemulsification time (p<0.0001) and ECD loss and irrigation solution volume (p<0.0001) in the Ringer group, but not in the BSS Plus group.

Conclusions

Ringers solution was similar to BSS Plus for corneal preservation in atraumatic cataract surgery. However, our study demonstrates that there is a trend towards lower postoperative endothelial cell density for surgeries with longer phacoemulsification time and higher irrigation volumes if Ringer is used.

Trial registration number

NCT00801358.

Comparison between Ringer's lactate and balanced salt solution on postoperative outcomes after phacoemulsfication: a randomized clinical trial

Aim:

To compare the effects of balanced salt solution (BSS) and Ringer's lactate (RL) on corneal thickness, endothelial morphology, and postoperative anterior chamber inflammation in eyes undergoing phacoemulsification.

Setting:

Iladevi cataract and IOL research center, Ahmedabad, India.

Materials and Methods:

This prospective randomized study comprised 90 consecutive patients with age-related cataract who were randomly assigned to either Group 1 (n = 45) with BSS or Group 2 (n = 45) with RL. Observations made included measurement of central corneal thickness (CCT), presence of anterior chamber flare and cells, endothelial cell loss, and change in coefficient of variation (CV). Data was analyzed using Mann Whitney test and test of proportion.

Results:

Mean increase in CCT on postoperative Day 1 was 58 µm and 97 µm in Groups 1 and 2 respectively (P = 0.01). Increase in CCT at one month was 10µm and 11µm in Groups 1 and 2 respectively (P = 0.99); increase in CCT at three months was 3 µm and 6 µm in Groups 1 and 2 respectively (P = 0.86). Number of eyes with flare grades in a range of 0 to 3 was statistically higher in Group 2 on postoperative Day 1 (P = 0.004, 0.016, <0.001, 0.047 for Grade 0, 1, 2 and 3 respectively). Number of eyes with cells of Grade 3 on first postoperative day was significantly higher in Group 2 as compared to Group 1 (P = 0.004). Three months postoperatively, endothelial cell loss was 5.5% and 7.8% in Groups 1 and 2 (P = 0.21) and change in CV was 3 and 5.4 in Groups 1 and 2 (P = 0.20) respectively.

Conclusion:

BSS offers a significant advantage over RL in terms of increase in corneal thickness and postoperative inflammation on the first postoperative day in patients undergoing phacoemulsification.

Rinsing with isotonic saline solution for eye burns should be avoided

BACKGROUND

Recent approaches to emergency treatment of eye burns have given rise to many questions on the effectiveness of traditional rinsing solutions. This led us to study the use of isotonic saline solution and a recently introduced, highly effective solution, Cederroth Eye Wash, in the initial treatment of eye burns.

METHODS

A central area (Ø 10mm) of the cornea of isolated ex vivo rabbit eyes was burnt for 20s with 25+/-1.4 micro L of 2N NaOH. The anterior chamber pH was measured continuously via microelectrode. The corneas were immediately rinsed for 15 min with flow rates of 50, 100, 200, 300, 400, and 500 mL/min.

RESULTS

After 20 min measurement, no significant differences in intraocular pH were found between unrinsed eyes and eyes rinsed with isotonic saline solution at any flow rate. At all flow rates, Cederroth Eye Wash brought about a significant decrease (p<0.001; Tukey t-test).

CONCLUSIONS

Isotonic saline solution was ineffective in the emergency treatment of severe alkali eye burns in this ex vivo rabbit eye model. Cederroth Eye Wash, even at the lowest flow rate, significantly reduced intracameral pH. Thus a small amount of buffer solution effectively decontaminated the eye, whilst large amounts of saline solution did not.

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.

EFFECT OF OXYGENATED INTRAOCULAR IRRIGATION SOLUTIONS ON THE ELECTRORETINOGRAM AFTER VITRECTOMY

PURPOSE

To investigate the effect of oxygenated intraocular irrigating solutions on electroretinograms (ERGs) for postvitrectomy rabbits.

METHODS

Eight groups of five rabbits each underwent pars plana vitrectomy on the right eye; the left eye of each rabbit served as control. The intraocular irrigating solutions were balanced salt solution (BSS), BSS-plus, BSS + oxygen (BSS + O2), BSS-plus + O2, and combinations of each with the addition of endoillumination (L). All animals were evaluated by single-flash scotopic electroretinography on the operated and nonoperated eyes before surgery and at 1 hour, 1 day, 1 week, and 1 month after surgery by an unmasked observer. The main outcome measures were dark-adapted b-wave amplitudes of operated eye/nonoperated eye ratios. The results for the different groups were compared by analysis of variance.

RESULTS

Mean dark-adapted b-wave amplitudes of operated eye/nonoperated eye ratios +/- SD for BSS-plus and BSS-plus + O2 before surgery and 1 hour, 1 day, 1 week, and 1 month after surgery were 1.01 +/- 0.09, 0.50 +/- 0.11, 0.95 +/- 0.11, 0.97 +/- 0.11, and 0.99 +/- 0.08 and 0.98 +/- 0.08, 0.59 +/- 0.10, 0.92 +/- 0.06, 0.97 +/- 0.08, and 0.97 +/- 0.10, respectively. At both 1 hour and 1 day after surgery, rabbits treated with BSS-plus + O2 had an earlier b-wave return to baseline findings, but the differences were not statistically significant (P > 0.05). Mean dark-adapted b-wave amplitudes of operated eye/nonoperated eye ratios +/- SD for BSS and BSS + O2 before surgery and 1 hour, 1 day, 1 week, and 1 month after surgery were 1.02 +/- 0.10, 0.47 +/- 0.09, 0.77 +/- 0.07, 0.89 +/- 0.07, and 0.89 +/- 0.07 and 1.02 +/- 0.06, 0.62 +/- 0.16, 0.94 +/- 0.09, 0.97 +/- 0.08, and 0.96 +/- 0.06, respectively. One hour and 1 day after surgery, ERG readings for rabbits treated with BSS + O2 exhibited a statistically significantly earlier return of ERG voltage to baseline values compared with both BSS and BSS + L (P = 0.05 and P = 0.02, respectively). One day after surgery, rabbits treated with BSS alone had the lowest ERG ratios. One week and 1 month after surgery, for all solutions tested other than BSS, ERG values were within normal limits.

CONCLUSION

The use of oxygenated solutions appears to affect ERG readings after pars plana vitrectomy. Further studies to evaluate the role of oxygenated solutions in different vitreoretinal surgical procedures are warranted.

The effects of different intraocular irrigating solutions on the apoptosis of cultured RPE cells

PURPOSE

To investigate the effect on porcine retinal pigment epithelial (RPE) cells of modified intraocular irrigating solutions compared with BSS and BSS plus.

METHODS

Confluent cultures of RPE cells were incubated in experimental intraocular irrigating solutions. The cells were then examined for breakdown of DNA by the TUNEL procedure. Fragmentation of the DNA from cells was also confirmed by flow cytometry.

RESULTS

Most of the experimentally, treated cells exhibited a shrunken appearance for up to 72 h. There was a steady increase in the number of cells labeled by the TUNEL method in three solutions with time. The data demonstrated that the influence of solutions on the percentage of RPE cell nuclei that gave a clear positive TUNEL stain was, in ascending order: modified solution>BSS>BSS plus. Of the three solutions tested, BSS plus showed least apoptosis.

CONCLUSIONS

It is suggested that BSS plus is less harmful to RPE cells than the other solutions tested. Introduction of other adjunctive solutions of antibiotics, mydriatics, miotics, and steroid, resulting in an altered electrolyte balance, pH, or osmolality in the solution, may compromise the safety and efficacy of a properly formulated and packaged solution.

Cataracts in New World camelids (llamas, alpacas, vicuñas, and guanacos)

Cataracts are the most frequently seen lens diseases in New World camelids. The causes of cataracts are unknown in many animals, but cataracts secondary to intraocular inflammation seem to be common. Congenital or juvenile-onset cataracts, if another cause is not apparent, should be considered as possibly caused by heredity, and the affected animals should not be bred. Persistent hyaloid vascular anomalies may also have an important role in cataract formation and could be heritable or caused by an in utero disturbance. Pedigree analyses, test breedings, and possibly DNA studies of llamas with cataracts will be required to determine their potential heritability in these species. Cataract surgery can be done successfully in camelids. It is important to evaluate the posterior segment with B scan ultrasonography before surgery in animals in which the posterior segment previously has not been seen. This evaluation allows the surgeon to better prepare for the presence of hyaloid vascular anomalies. Use of phacoemulsification, gentle tissue handling, liberal use of anti-inflammatory medications and endothelial protectants (BSS + and viscoelastics) during surgery has increased the success rate of this surgery in camelids. Unlike cataract surgery in dogs and horses undergoing, cataract surgery, in camelids seems to be important to remove much of the posterior lens capsule. This removal prevents severe capsular fibrosis and subsequent vision loss. There is evidence that a posterior capsulectomy and anterior viterectomy can help prevent postoperative glaucoma. Research needs to be done to see whether these species have an increased risk for ciliary-block glaucoma.

Analysis of aqueous humor obtained from normal eyes of llamas and alpacas

OBJECTIVE

To evaluate composition of aqueous humor obtained from normal eyes of llamas (Lama glama) and alpacas (Lama pacos).

SAMPLE POPULATION

Aqueous humor obtained from 10 male llamas and 10 male alpacas.

PROCEDURE

All animals had normal eyes, as determined by ocular examination. Aqueous humor samples were obtained via paracentesis of the anterior chamber of animals that were heavily sedated. Chemical analysis included measurement of concentrations of sodium, potassium, magnesium, chloride, bicarbonate, phosphorus, and glucose as well as osmolality and pH.

RESULTS

With the exception of potassium concentrations, values for aqueous humor composition did not differ significantly between llamas and alpacas. Mean +/- SD values for llamas and alpacas, respectively, were: sodium, 154.7 +/- 2.1 and 152.7 +/- 2.1 mEq/L; potassium, 5.3 +/- 0.4 and 4.6 +/- 0.4 mEq/L; magnesium, 1.8 +/- 0.1 and 1.7 +/- 0.1 mg/dl; chloride, 130.0 +/- 1.6 and 127.0 +/- 3.3 mEq/L; bicarbonate, 19.2 +/- 1.5 and 20.2 +/- 2.3 mEq/L; phosphorous, 2.7 +/- 0.3 and 2.5 +/- 0.4 mg/dl; glucose, 80.3 +/- 3.9 and 80.8 +/- 7.3 mg/dl; total protein, 29.0 +/- 8.6 and 31.5 +/- 10.1 mg/dl; and osmolality, 305.8 +/- 11.8 and 306.2 +/- 4.9 mOsm. The pH ranged from 7.5 to 8.0 for both species. Potassium concentrations were significantly higher in llamas than alpacas.

CONCLUSIONS AND CLINICAL RELEVANCE

Except for potassium, composition of aqueous humor did not differ significantly between llamas and alpacas. Aqueous humor composition of llamas and alpacas is similar to that of other species that have been examined.

The resiliency of the corneal endothelium to refractive and intraocular surgery

PURPOSE

To describe stress factors (phenylephrine and contact lenses) from the corneal epithelium that can affect the corneal endothelium, and to describe the effects of refractive and intraocular surgery on the corneal endothelial structure and function.

METHODS

Significant clinical and experimental publications are reviewed and recent experiments conducted in the author's laboratory to describe the corneal endothelial stresses.

RESULTS

The corneal epithelium serves as a barrier to topical phenylephrine (2.5-10%). In a compromised epithelium, topical phenylephrine will cause drug-induced stromal edema and endothelial vacuolization. Contact lenses are capable of stimulating the epithelial arachidonic acid cascade to release 12(R)hydroxyeicosatetraenoic acid (12(R)HETE) and 8(R)hydroxy-hexadecatrienoic acid (8(R)HHDTrE) to cause endothelial Na+/K+ adenosine triphosphatase (ATPase)-inhibition and polymegethism. Specular microscopy of the corneal endothelial cells after refractive surgery (photorefractive keratectomy [PRK], laser in situ keratomileusis [LASIK], intrastromal rings [INTACs]) has shown that there is minimal effect. However, laser ablation of the stroma within 200 microm of the corneal endothelium will result in endothelial cell structural changes and the formation of the amorphous substance deposited onto Descemet's membrane. Phacoemulsification with a high flow of the irrigation solution can alter the endothelial surface glycoprotein layer. Lidocaine hydrochloride (1%) used as intracameral anesthesia readily diffuses through the corneal endothelium, resulting in stromal uptake and endothelial cell swelling. With phacoemulsification, however, the washout of lidocaine from the cornea (T1/2, 5 minutes) and iris (T1/2, 9 minutes) occurs quickly. Corneal endothelial wound healing after keratoplasty occurs in the following sequence: migration of endothelial cells, development of tight junctions, and the formation of Na+/K+ ATPase pump sites.

CONCLUSIONS

Corneal endothelial resiliency is due to the increased peripheral endothelial cell number for migration, the ability of endothelial cells to form tight junctions to maintain the endothelial barrier, the increase in endothelial Na+/K+ ATPase pump sites under stress, and the ability of the corneal endothelial cells to shift their metabolism of glucose to the hexose monophosphate shunt for the production of nicotinamide adenine dinucleotide phosphate (NADPH) and membrane repair. All of these factors are important, along with the aqueous humor sodium concentration, which establishes the osmotic gradient for corneal deturgescence and transparency.

Effect of irrigating solution and irrigation temperature on the cornea and pupil during phacoemulsification

PURPOSE

To evaluate the effect of irrigation solution and temperature on pupil diameter, corneal endothelium, and corneal pachymetry during and after phacoemulsification.

SETTING

Klinik Dardenne, Bonn, Germany.

METHODS

Eighty patients who had cataract surgery by phacoemulsification were assigned to 1 of 4 cross-classified groups and had intraoperative irrigation with room-temperature or refrigerated fortified balanced salt solution (BSS Plus) or modified Ringer's solution. Pupil diameters were recorded at different stages during the surgery. Epithelial cell counts and pachymetry were determined before and 1 day after surgery.

RESULTS

The solution temperature did not affect any parameter. The type of solution did not influence endothelial cell loss; however, the solution had a significant effect on corneal pachymetry 1 day postoperatively. The corneas irrigated with BSS Plus were less swollen than the corneas irrigated with Ringer's solution. By day 14, corneal thickness was equal among all groups.

CONCLUSION

Long-term results were equally favorable in all 4 groups. However BSS Plus induced less short-term corneal swelling than Ringer's solution. From these findings, it appears that BSS Plus may decrease corneal risk in cases with compromised corneas or prolonged surgery.

The tolerability of lactated Ringer's solution and BSS plus for ocular irrigation with and without the Morgan therapeutic lens

OBJECTIVE

To evaluate two solutions, lactated Ringer's (LR) and a balanced salt solution (BSS Plus, Alcon Laboratories, Ft. Worth, TX), compared with normal saline solution (NSS), for ocular irrigation in healthy adult volunteers with and without the Morgan therapeutic lens (MTL).

METHODS

This was a prospective, double-blind, randomized study of healthy volunteers who were at least 18 years of age. Exclusion criteria included the use of analgesics within four hours of the study. A complete ophthalmologic examination was performed at baseline and at the completion of the study. Following randomization and prior to any intervention, baseline discomfort scores were obtained by means of a verbally administered, horizontal, 100-mm, unnumbered analog discomfort scale. Both eyes of each volunteer were irrigated simultaneously for 15 minutes, with additional discomfort scores being recorded every 5 minutes using the same 100-mm, unnumbered analog discomfort scale. A global evaluation to assess the method of irrigation and the solutions used for irrigation was completed by both the physician blinded to the treatment groups and the volunteers. The volunteers were continuously monitored for any adverse effects resulting from the irrigation solutions or MTL.

RESULTS

Sixty-three volunteers were recruited into the study, with 61 entered in the final analysis. Age and gender were balanced within each group. There was no significant difference in discomfort scores between the two groups; however, all discomfort scores decreased over time (p = 0.008). A lens-solution interaction was identified, with LR being the most tolerated when administered with the MTL. A statistically higher ocular pH difference was seen between the pre- and postirrigation readings for the control eye in volunteers irrigated with MTL (p = 0.046). Analysis of the global evaluations for each group revealed no difference in the distributions of physician and volunteer scores. No adverse event was reported in either group.

CONCLUSION

There does not appear to be any difference in discomfort scores between the ocular irrigation fluids when used without the MTL. Overall, the use of the MTL appears well tolerated by healthy, adult volunteers. However, there does appear to be a significant lens-solution effect on volunteers' discomfort scores, with LR having significantly lower discomfort scores when used for ocular irrigation with the MTL. The authors conclude that the use of the MTL for ocular irrigation is well tolerated and recommend using LR as the irrigation solution for maximal patient comfort.

Effect of intraocular irrigating solutions on the viability of cultured retinal vascular endothelial cells

PURPOSE

To compare the abilities of balanced salt solution, BSS Plus and Hartmann's lactated Ringer's (HLR) solution to maintain the viability of retinal vascular endothelial cells (RVEC) in vitro.

METHODS

Cultured retinal vascular endothelial cells were suspended in each irrigating solution for four hours. Viability was determined by trypan blue exclusion at 30 minute intervals. Regression analysis was used to determine the rate of viability loss. Additional studies were performed to determine the effectiveness of lactate in maintaining cell viability.

RESULTS

Retinal vascular endothelial cells lost viability at a greater rate (p < 0.001) in BSS (8.7%/hr) compared with BSS Plus (3.3%/hr). Cells in Hartmann's lactated Ringer's lost viability at a significantly lower rate (4.4%/hr) than retinal vascular endothelial cells in lactate-free Hartmann's lactated Ringer's solution (8.4%/hr). Lactate was as effective as glucose in preserving RVEC viability. By comparison, the viability of corneal endothelial cells was not effectively maintained by lactate. For these cells, BSS Plus was clearly superior to Hartmann's lactated Ringer's solution in maintaining viability.

CONCLUSIONS

BSS Plus and Hartmann's lactated Ringer's solution are both superior to balanced salt solution in maintaining retinal vascular endothelial cell viability. For retinal vascular endothelial cells, Hartmann's lactated Ringer's solution preserves cell viability as well as BSS Plus, since the retinal vascular endothelial cells, unlike corneal endothelial cells, can apparently utilize lactate as an energy source.

Effects of acetylcholine and carbachol on bovine corneal endothelial cells in vitro

PURPOSE

To assess the relative cytotoxicity of Miochol (1% acetylcholine and mannitol), Miostat (0.01% carbachol, sodium, potassium, magnesium, and calcium salts), and their individual components using in vitro models of bovine corneal endothelial cells (BCECs).

SETTING

Laboratories of the Departments of Ophthalmology and Physiology, The University of Texas Health Science Center, Houston.

METHODS

The study was divided into four experiments. Experiment 1 used a confluent model to compare the relative cytotoxicity of Miochol and Miostat on BCECs following short-term exposure. In Experiments 2, 3, and 4, the proliferation model (preconfluent BCECs) was used to detect the possible cytotoxicity of individual components in the commercial preparations of the miotics; i.e., the preconfluent BCECs were exposed to buffered salt solutions containing mannitol (1%, 3%, and 4%), acetylcholine (0.5%, 1%, and 2%), or carbachol (0.1%, 0.5%, and 1%) for 3 hours.

RESULTS

Confluent BCECs exposed to Miochol for 30 minutes underwent necrosis and degeneration, while those treated with Miostat did not show any morphological changes. None of the tested solutions except 2% acetylcholine and 1% carbachol caused observable changes in the nuclear densities of BCECs at 24, 72, 120, and 168 hours.

CONCLUSION

The major components of Miochol (acetylcholine and mannitol) were found to be nontoxic; the cytotoxicity of the preparation was possibly due to the lack of an appropriate balanced salt solution. These findings may influence the selection of a miotic for use during intraocular surgery.

A comparative study of intraocular irrigating solutions: effects on electroretinography readings during closed vitrectomy in humans

The effects of intraocular irrigating solutions on electroretinography have been extensively studied in animal models, but effects on human electroretinography have not been reported. This study examined the effects of two commercially available irrigating solutions, S-MA2 (Opeguard MA) and DE-057 (BBS-Plus) on 30-Hz flicker electroretinography during closed vitrectomy in humans. Eight eyes of 8 patients were examined. All patients underwent a simple vitrectomy without treatment of proliferative membrane. For 30-Hz flicker electroretinography recording, a contact lens with a built-in light-emitting diode was sterilized and used as both a stimulus source and a recording electrode. Replacing S-MA2 with DE-057 decreased the electroretinography amplitude from 55.8 +/- 15.2 to 45.5 +/- 13.2 microV (mean +/- SEM). Changing the irrigation solution from DE-057 back to S-MA2 increased the amplitude from 45.5 +/- 13.2 to 59.9 +/- 17.3 microV. However, these changes were not statistically significant. Replacing S-MA2 with DE-057 significantly increased the peak time from 50.1 +/- 1.5 to 57.6 +/- 1.3 msec (p < 0.001). This change was reversible; after changing from DE-057 back to S-MA2, the peak time of flicker electroretinography significantly decreased from 57.6 +/- 1.3 to 49.0 +/- 2.1 msec (p < 0.01). Thus intraoperative 30-Hz electroretinography showed delayed peak time during irrigation with DE-057, as compared with S-MA2. The lower potassium concentration and higher glucose concentration of S-MA2, as compared with DE-057, may be the cause of such electroretinography changes.

Intraocular irrigating solutions. A randomized clinical trial of balanced salt solution plus and dextrose bicarbonate lactated Ringer's solution

BACKGROUND

Two intraocular irrigating solutions which differ principally by the presence of oxidized glutathione were compared in this randomized, masked, prospective study to discern differences in preservation of endothelial cell size.

METHODS

Sixty-four patients undergoing extracapsular cataract extractions were randomized between two irrigating solution groups, Balanced Salt Solution (BSS) Plus (n = 30) and dextrose bicarbonate lactated Ringer's solution (n = 34). Preoperative and postoperative endothelial specular photomicrographs were analyzed for cell size and hexagonality, and the two groups were compared using repeated measures analysis of variance.

RESULTS

Fifty-eight subjects (91%) completed the 2-month study. Change in cell size for the BSS Plus group (n = 28) (mean +/- standard error, 29.4 +/- 12.3 microns2) was not significantly different from the dextrose bicarbonate lactated Ringer's solution group (n = 30) (27.5 +/- 12.9 microns2) (P = 0.92). Groups did not differ significantly in percent hexagonality (P = 0.57) or in the variability of cell size (P = 0.61).

CONCLUSION

The presence of glutathione in BSS Plus and other minor electrolyte differences between the solutions is not more advantageous with regard to endothelial cell size than dextrose bicarbonate lactated Ringer's solution for standard extracapsular cataract surgery. Cost per 500-microliters bottle of BSS plus is $62 compared with $9.80 for dextrose bicarbonate lactated Ringer's solution.

Effects of irrigation solutions on corneal endothelial function

Rabbit corneas were perfused in vitro with an irrigation solution for 90 minutes. This was followed by 6 hours of perfusion with tissue culture medium TC199 during which endothelial function was assessed by monitoring rates of swelling during a period of perfusion in the absence of bicarbonate ions, and subsequent rates of thinning when bicarbonate ions were restored to the perfusate. Corneal thickness (measured with an ultrasonic pachymeter) immediately following excision was 401 microns (SD 19, n = 23). During the 90 minute perfusion at 35 degrees C, corneas exposed to balanced salt solution (BSS), Hartmann's solution or 0.9% NaCl (all initially at room temperature) swelled, respectively, at 14 (SD 2.3, n = 4), 11 (SD 2.6, n = 4), and 70 (SD 4.3, n = 4) microns/h. Cold Hartmann's solution (initially at 4 degrees C) caused corneas to swell at 9 (SD 2.3, n = 4) microns/h. On the other hand, corneas perfused with BSS Plus thinned at 9 (SD 3.4, n = 4) microns/h and TC199 with Earle's salts had little effect on thickness. Rates of swelling and thinning during the following assessment perfusion showed no apparent effects of prior exposure to any of the irrigation solutions on the barrier properties or pump function of the endothelium. Despite this, the increased thickness of corneas exposed initially to BSS, cold Hartmann's solution, or 0.9% NaCl was not fully reversed, even by the end of the 6 hour assessment perfusion. In contrast, the swelling observed in corneas exposed to Hartmann's solution at room temperature was reversed and these corneas had returned to their normal thickness by the end of the assessment period. All corneas, even those exposed to 0.9% NaCl, had an intact endothelial mosaic with no evidence of damage or cell loss, although morphological differences in cell shape and the appearance of cell borders were evident compared with freshly isolated cornea.

Corneal endothelial permeability of human tissue after storage in Optisol

The purpose of this study was to compare Optisol to moist chamber storage for maintaining human corneal endothelial barrier function. Human corneas preserved in Optisol were stored for up to 35 days at 4 C. Endothelial carboxyfluorescein permeability (P(ac)) was measured and endothelial ultrastructure was evaluated by electron microscopy. Endothelial P(ac) (x 10(-4) cm/min) of Optisol-stored corneas was 1.7, 2.0, and 3.1 at five, seven, and 14 days, respectively. The P(ac) increased to 6.5 at 35 days of storage. Endothelial P(ac) in moist chamber stored-eyes was 2.6 at two days, and increased to 13.5 14 days of storage. Multiple regressional analysis showed that storage time and donor age affected P(ac); but time from death to enucleation, time from enucleation to storage, or endothelial cell number did not. Electron microscopy showed that endothelial junctions were maintained through two weeks by Optisol. Large areas of cellular destruction were seen after five days of moist chamber storage. These results show that Optisol can preserve endothelial barrier function through 14 days; barrier function is lost by three days of moist chamber storage.

Retinal separation, retinotomy, and macular relocation: I. Experimental studies in the rabbit eye

An animal model in the rabbit eye was utilized to study mobilization and relocation of the fovea as a potentially beneficial surgical approach to age-related macular disease. After lentectomy and vitrectomy, the retina was completely separated from the pigment epithelium by means of infusion into the subretinal space. A 360 degrees peripheral retinotomy was performed. The retina was rotated up to 60 degrees around the optic nerve as axis and reattached. Scanning and transmission electron microscopy revealed the relative intactness of outer segments and pigment epithelium after this procedure, both acutely and 3 days following reattachment.

Rapid toxicological model for use in assessing ocular drugs

Nonsteroidal antiinflammatory drugs (NSAIDs) were applied to corneas either by in vitro or in vivo methods. The in vitro method involved excising and mounting corneas in a perfusion system at 37 degrees and exposing drug for 2.5 h. The in vivo methods represent either topical administration to the rabbit eye or topical in vivo infusion using a fixed well which permitted a constant concentration (0.05 per cent) to be applied to the eye of anesthetized rabbits for up to 120 min. An overlay grid procedure using scanning electron microscopy (SEM) showed less per cent endothelial damage with in vivo methods than with the in vitro method of administration, but per cent damage depended on which section was viewed. Damage to the epithelium and endothelium were also assessed by quantitative carboxyfluorescein and Janus green staining and uptake procedures, respectively, following drug exposure by the in vivo infusion method. Results for the epithelium indicated that the more lipophilic NSAIDs damaged the epithelial layer to a greater degree than newly synthesized hydrophilic NSAIDs. Damage to the epithelium correlated to the surface activity of the NSAIDs. Qualitative assessment of epithelial and endothelial toxicity can be performed with SEM and transmission electron microscopy (TEM) while vital staining procedures and the SEM grid procedure can be used to quantitatively assess corneal toxicity. The staining methods, however, possess advantages over SEM and TEM procedures in that they are rapid and do not require laborious preparation. As a result of these characteristics, the vital staining procedures could be used as part of a biopharmaceutical screening technique in evaluating new ophthalmic drugs.

Comparison of the effects of intraocular irrigating solutions on the corneal endothelium in intraocular lens implantation

We conducted a randomised prospective controlled study to determine the effects of a glucose glutathione bicarbonate solution (BSS Plus) and a citrate acetate bicarbonate solution (S-MA2) on the corneal endothelium in patients undergoing extracapsular cataract extraction with posterior chamber lens implantation. One eye of each patient was randomly assigned to receive BSS Plus, and the other eye to receive S-MA2. BSS Plus caused significantly less corneal swelling on the first postoperative day than did S-MA2. There was no difference between the two solutions in their effect on corneal thickness one week and one month postoperatively. Computer assisted morphometric analysis of wide-field specular microscopic photographs demonstrated minimal changes in endothelial morphological characteristics in the eyes irrigated with BSS Plus. By comparison S-MA2, caused a significant loss of endothelial cells and a marked reduction in the figure coefficient. These results indicated that BSS Plus has a clinical advantage over S-MA2 with respect to the corneal endothelium.

Clinical comparison of ocular irrigation fluids following chemical injury

This study tested the hypothesis that four ocular irrigating solutions were equally irritating during copious irrigation. We conducted a prospective, double-blind study of patients with chemical exposure to the eye. Each underwent cross-over irrigation with all of the following in random order: normal saline (NS), lactated Ringer's (LR), normal saline adjusted to pH 7.4 with sodium bicarbonate (NS + Bicarb), and Balanced Saline Solution Plus (BSS Plus, Alcon Laboratories, Fort Worth, TX). Compared with traditional NS and LR, NS + Bicarb tended to be more comfortable. BSS Plus was statistically superior (P less than .05) to NS and preferred over LR and NS + Bicarb. Three patients demanded discontinuance of NS or NS + Bicarb infusions. All solutions had comparable normalization of conjunctival pH and degree of injection. Alternate solutions including BSS Plus should be considered for use in those patients whose poor tolerance to normal saline threatens to delay or interrupt eye irrigation following a chemical injury.

Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker

We evaluated the occurrence or progression of nuclear sclerosis of the crystalline lens in 100 eyes after vitrectomy for removal of idiopathic epiretinal membranes causing macular pucker. The follow-up period ranged from six to 99 months (average, 29 months). Visually significant nuclear sclerosis was present preoperatively in three of the operated on eyes and four of the fellow eyes. The rate of occurrence or progression of visually significant nuclear sclerosis was far greater in the operated on eyes (P less than .0001). Of 100 patients, 80 operated on eyes and 24 fellow eyes had visually significant nuclear sclerosis or had undergone previous cataract extraction at the conclusion of the study. Different concentrations of glucose in the intraocular irrigating solution did not affect occurrence of later nuclear sclerosis. Patients older than 50 years of age had a far greater incidence of later nuclear sclerosis than patients younger than 50 years of age (P = .0003). Nuclear sclerosis may be caused by altered lens metabolism after removal of part of the vitreous gel, since nuclear sclerosis also occurs in other conditions associated with vitreous liquefaction.

A method for the in vitro determination of feline corneal endothelial permeability

A mounting block for in vitro perfusion of the cat cornea is described. Using this apparatus and the techniques of Araie, the permeability (Pac) of the normal cat corneal endothelium to carboxyfluorescein was determined to be 2.5 +/- 0.2 x 10(-4) cm/min. To assess the sensitivity of this technique in determining changes in Pac associated with alterations in endothelial, morphology, three cats underwent 2 successive unilateral, central, 10 mm diameter circular areas of endothelial debridement 6 weeks apart. Six weeks following the second wounding all 3 animals underwent morphometric analysis and Pac determination. A trend toward an elevation in Pac with extreme reductions in cell density was observed.

In vitro corneal endothelial permeability in rabbit and human: the effects of age, cataract surgery and diabetes

Endothelial permeability was examined in rabbit and human corneas using an in vitro perfusion system with 5(6)-carboxyfluorescein as the permeability tracer. Following endothelial removal, the permeability of de-epithelialized rabbit corneas increased from 3.19 x 10(-4) cm min-1 to 31.21 x 10(-4) cm min-1, and de-epithelialized human donor corneal permeability values increased from 2.26 to 12.85. In human corneas, no correlation was seen between endothelial permeability and donor age, moist chamber storage time, endothelial cell density, coefficient of variation of cell area, or percent hexagonal cells. A positive correlation was found between permeability and time between donor death and enucleation. Donor eyes from three separate populations, having undergone cataract surgery prior to death (aphakic, posterior and anterior chamber implants), all showed a significant increase in permeability. Neither Type I nor Type II diabetes had an effect on the endothelial permeability of human donor corneas.

Comparison of intraocular solutions on glycolysis and levels of ATP and glutathione in the retina

The effects of several intraocular irrigating solutions on the rate of glycolysis and the levels of ATP and glutathione in the isolated rat retina were investigated. The media were HCO3-Ringer, balanced salt solution (BSS) (to which 5 mM glucose was added), and BSS PLUS. There were no significant differences in the metabolic activities and metabolite levels in retinas incubated with either HCO3-Ringer or BSS PLUS. Retinas incubated with BSS PLUS had higher rates of aerobic and anaerobic glycolysis and more ATP than did retinas incubated with BSS. There were no significant differences, however, in the glutathione content of retinas incubated with BSS PLUS and BSS. These results show that retinal energy metabolism is maintained better with BSS PLUS because this irrigating solution contains glucose and bicarbonate.

K-Sol corneal preservation at room temperature

K-Sol, a recently developed corneal storage medium that contains purified chondroitin sulphate in tissue culture medium (TC 199), is capable of preserving corneal tissue for 14 days at 4 degrees C. To study the effect of tissue storage in K-Sol at room temperature we preserved rabbit corneas in K-Sol and M-K medium for three or seven days at 25 degrees C. All of the corneal endothelial sheets were intact after three days. At seven days the change in pH of the K-Sol medium was less than that of M-K medium. Corneas preserved in M-K medium showed swelling of mitochondria and a decrease in the number of cytoplasmic organelles. Corneas preserved in K-Sol had organised cytoplasmic organelles and nuclei. Scanning electron micrographs revealed well preserved endothelial sheets. Corneas stored in the two media showed no significant difference in thickness. A pair of human corneas preserved in K-Sol at room temperature for six days maintained about 95% of the endothelial sheet in good condition. Small separations were observed between some of the endothelial cells. However, even in these areas, the cytoplasmic organelles were well preserved. It appeared that K-Sol is more stable than M-K medium at room temperature, and that both rabbit and human corneas can be preserved in good condition in K-Sol for at least six days at 25 degrees C.

Nuclear sclerosis after vitrectomy for idiopathic epiretinal membranes

We performed a retrospective analysis of lens changes occurring after vitrectomy for idiopathic epiretinal membranes causing macular pucker on 75 consecutive phakic eyes. Thirty-five eyes (47%) had appearance or progression of nuclear sclerosis. There were no changes in anterior subcapsular cataracts and three eyes (4%) had minimal changes in posterior subcapsular cataracts. Based on univariate analysis, presence of preoperative nuclear sclerosis, length of follow-up period, and surgeon were found to be associated with the occurrence or progression of nuclear sclerosis. Differences between surgeons were largely accounted for by the difference in proportions with preoperative nuclear sclerosis, and differing lengths of follow-up. Kaplan-Meier life table analysis performed on 53 eyes with examination of fellow eyes and longer follow-up showed significantly more nuclear sclerosis in the operated on eye when compared to the fellow eye (log-rank test, P less than .0001).

Role of the intraocular irrigating solutions in the pathogenesis of the postvitrectomy retinal edema

Alterations in the vitreo-retinal barrier can modify the exchange of water taking place between the retina and the vitreous body and cause retinal edema to develop. To verify this fact, albino rabbits were subjected to vitrectomies perfusing various intraocular irrigating solutions for various durations. The following conclusions were drawn from these experiments: Ringer's Lactate and physiological saline solutions are more edematogenous than BSS plus; the induced edema is more severe, the longer the perfusion. We have also confirmed that this edema is inhibited by topically administered indomethacin, which proves that in the rupture of blood-retinal barriers during the vitrectomy, prostaglandins play an important role.

Corneal epithelial Cl-dependent pump quantified

Pairs of rabbit corneas were perfused and corneal thickness monitored. The epithelial side of the preparation, and after stabilization also the endothelial side, was covered with silicone oil. A constant thinning of the cornea was observed at a rate of 11.1 microns hr-1 (= 1.0 micron L h-1 cm-2) S.D. 2.1, n = 9. This thinning was also present after endothelial removal: 12.3 microns hr-1, S.D. 1.6 (n = 5). Epithelial abrasion virtually abolished the thinning (2.5 microns hr-1, S.D. 1.89, n = 4), as did cooling from 34 to 0 degrees C. When the preparation was perfused with a Cl-free solution (SO4(2-) instead of Cl-, corrected for osmolarity with sucrose) no significant thinning of the preparation was observed (2.4 microns hr-1, S.D. 2.49, n = 4) after covering both surfaces with silicone oil. This simple set of experiments quantified the epithelial pump mechanism. The epithelial pump rate of about 1.2 microns L hr-1 cm-2 has to be taken into account when endothelial pump rates are measured in the in vitro preparation with intact epithelium.

BSS Plus: a potential irrigating solution for neurosurgery

BSS Plus is a pH-stable balanced salt solution similar to glutathione bicarbonate Ringer's solution. Extensively used in ophthalmology, it is of potential value in neurosurgery. In comparative tests of its effectiveness, 28 cats underwent bilateral irrigation of the surface of the cerebral cortex with normal saline on one side and BSS Plus on the other. After 2 hours, a marked decrease was seen in the surface pH of the hemisphere irrigated with normal saline but not of the hemisphere treated with BSS Plus. Blood-brain barrier changes (measured with Evans blue dye techniques) were more evident following saline irrigation. Somatosensory evoked potentials and cerebral blood flow were not significantly altered. Conventional light microscopy using three standard stains did not reveal a significant difference. Transmission electron microscopy studies were performed in 14 animals and scanning electron microscopy in six. In five animals both transmission and scanning electron microscopy studies were conducted after irrigation with both agents without a cottonoid cover and with immediate harvest of superficial layers from the living brain and immersion-fixation in glutaraldehyde. Tissue preservation was superior on the BSS Plus side in all studies. This agent may represent an improved irrigation solution for neurosurgery, but further studies are required.

Comparison of intraocular irrigating solutions in pars plana vitrectomy

A prospective, randomized, masked clinical study was conducted to examine the effects of pars plana vitrectomy on the corneal endothelium comparing Balanced Salt Solution (BSS) to BSS-Plus as an intraocular irrigating solution. Seventy-one patients were followed for at least six months. A significant 6.9% decrease in endothelial cell density was observed among all patients at six months postoperatively, compared to preoperative values, using the contralateral eye as a control. However, no significant difference in endothelial cell loss was found between BSS and BSS-Plus eyes. Both aphakic eyes and those undergoing lensectomy (with vitrectomy) showed a significantly greater reduction of endothelial cell density at six months compared to phakic eyes. No significant difference in corneal thickness was observed at six months postoperatively compared to preoperative values. For the one-year duration of our study BSS was as efficacious in preserving the integrity of the corneal endothelium as was BSS-Plus.

Posttraumatic autoimmune reaction in peripheral nerve: effect of a single injury

This study was conducted to show that local autoimmune reactions could be observed in rat sciatic nerve after a single injury. Furthermore, we attempted to correlate the intensity of the immunological reaction with the severity of nerve damage, with the type of surgical treatment and with the degree of functional recovery. Through the use of direct immunofluorescence techniques, we found that the severity of the initial damage was associated with the intensity of the local immunological response assessed 2.5 months after surgery. There was an association between type of surgical treatment and intensity of the autoimmune reaction. A correlation between autoimmune reaction and degree of long-term functional impairment was not immediately clear. The probable factors that underlie these results are discussed.