Corneal edema and the intraocular use of epinephrine

The Effects of Donor-Recipient Age and Sex Compatibility in the Outcomes of Deep Anterior Lamellar Keratoplasties

Purpose

Corneal transplantations are the commonest allogenic transplant surgeries performed worldwide. Transplantable grade donor cornea is a finite resource. There is thus an impetus for eye banks to optimize the use of each harvested cornea, and clinicians to minimize the risks of graft rejection and failure. With better survival and lower rejection rates, anterior lamellar keratoplasty has gained popularity as an alternative technique to full-thickness penetrating keratoplasty, for the treatment of corneal stromal diseases. This study evaluated the effects of donor-recipient age- and sex-matching on the outcomes of eyes that had undergone deep anterior lamellar keratoplasty (DALK) surgeries.

Design

Observational cross-sectional study (national corneal graft registry data).

Subjects

All DALK surgeries performed in a tertiary ophthalmic hospital over an 11-year period.

Methods

To analyse the effects of donor-recipient sex-matching, transplantations were classified as “presumed H-Y incompatible” (male donor to female recipient) or “presumed H-Y compatible” (all other donor-recipient sex combinations). For age-matching, differences in donor and recipient ages were calculated. Cox proportional hazards regressions were used to evaluate the influence of donor-recipient sex-matching and age-matching on graft failure and rejection.

Main Outcome Measures

Rates of graft failure and rejection within each group.

Results

401 eyes were included. 271 (67.6%) transplants were presumed H-Y compatible. 29 (7.2%) grafts failed and 9 (2.2%) grafts rejected. There were trends of lower hazard ratios (HRs) in graft failure and rejection in the presumed H-Y compatible group [HRs: 0.59 (95% CI 0.20–1.77, p = 0.34) and 0.93 (95% CI 0.22–3.89, p = 0.926), respectively]. Median difference in age between recipients and donors was 15.0 years (IQR −2.8–34.3). The HRs of graft failure and rejection were not influenced by donor-recipient age [HRs per 1-year increase in age difference: 0.995 (95% CI 0.98–1.01, p = 0.483) and 1.01 (95% CI 0.99–1.03, p = 0.394), respectively].

Conclusion

In eyes that had undergone DALK surgeries, no significant influence of donor-recipient sex- or age-matching on graft rejection and failure was observed. Without strong evidence and the limitations of obtaining sample sizes required for an adequately powered study, the benefits of sex- and age-matching of donors and recipients during graft allocation for DALK surgeries is currently inconclusive.

Correlation between Corneal Endothelial Cell Density and Central Ocular Surface Temperature in Normal and Keratoconus Eyes

PURPOSE

In keratoconus (KC), an increase of the corneal back surface area may result in endothelial cell density (ECD) decrease and an increase of the corneal front surface area in ocular surface temperature (OST) decrease due to increased heat dissipation. Along with these hypotheses, we aimed to analyse the correlation between ECD and central corneal OST in patients with KC and healthy controls.

PATIENTS AND METHODS

A total of 154 eyes with KC (mean age 36.1 ± 12.5 years) and 92 healthy eyes (mean age 36.4 ± 12.8 years) were examined. Corneal front and back surface area at the central 5 mm corneal diameter (FSA and BSA) were calculated based on Pentacam measurement data:FSA or BSA = 2×3.14×R(R-√R²-D/2)²,where R referred to corneal front or back surface radius of curvature and D to the corneal front or back surface diameter (5 mm for the present study), respectively.ECD was determined by specular microscopy (EM-3000) and central corneal OST by thermography (TG-1000).

RESULTS

ECD was significantly lower in KC (2498 ± 356/mm²) patients than in controls (2638 ± 294/mm²; p < .001). FSA (20.35 ± 0.26 mm² vs. 20.17 ± 0.03 mm²) and BSA (20.84 ± 0.58 mm² vs. 20.45 ± 0.08 mm²) were significantly higher in KC patients than in controls (p = .001; p < .001), but the average central corneal OST did not differ significantly between both groups (34.2 ± 0.6°C vs.34.3 ± 0.7°C; p = .62). OST at the corneal centre correlated weakly, positively with ECD (r = 0.2; p < .05), but OST did not correlate with FSA (r = 0.045) or BSA (r = 0.064).

CONCLUSIONS

Endothelial cell density seems to have a mild impact on central ocular surface temperature in keratoconus and normal subjects. This effect is not correlated to the corneal front or back surface area.

Phaco-antigenic glaucoma following uncomplicated cataract surgery

INTRODUCTION

Phaco-antigenic glaucoma occurs in less than 1% of cataract surgeries. Managing this rare complication is challenging, especially when there are few documented cases reported. We describe the challenges of managing a case of bilateral phaco-antigenic glaucoma following uncomplicated cataract surgery requiring viscocanalostomy.

CASE DESCRIPTION

An 82-year-old atopic lady presented with a 2-day history of painful injected right eye. She was 4 days post left and 8 days post right uncomplicated cataract surgery. On examination, the anterior chambers were deep with no hypopyon. Intraocular pressure was raised at 38 mmHg in the right eye and 24 mmHg in the left eye initially. However, intraocular pressure remained uncontrolled despite maximum medical treatment; she attended A + E six times within 11 days with intraocular pressures of up to 48 mmHg in the right eye and 46 mmHg in the left eye. A vitreous biopsy was reported negative for infective organisms. Eventually, bilateral viscocanalostomies were performed and vision improved to 0.24 logMAR in both eyes with intraocular pressures of 8 mmHg in the right eye and 10 mmHg in the left eye.

CONCLUSION

We present a rare presentation of phaco-antigenic glaucoma following an uncomplicated cataract surgical procedure with good results following timely intervention.

Efficacy of 0.015% intracameral epinephrine for significant miosis induced by photodisruption during femtosecond laser-assisted cataract surgery

Despite the various advantages of femtosecond laser-assisted cataract surgery (FLACS), pupillary constriction during laser photodisruption is considered one of the most unfavorable events. This study aimed to investigate the efficacy of intracameral 0.015% epinephrine injection for miosis after laser pretreatment during FLACS.A total of 82 patients who underwent FLACS for age-related cataracts were investigated in this retrospective study. The epinephrine group included patients who received intracameral epinephrine injection for miosis after femtosecond laser pretreatment, while the no-epinephrine group included the patients who underwent FLACS without intracameral epinephrine due to minimal miosis. Quantitative pupil area measurements were performed through the analysis of captured images extracted from surgical videos of both femtosecond laser pretreatment and phacoemulsification.Laser photodisruption induced miosis in both groups, although the degree of miosis was greater in the epinephrine group (4.65 ± 0.87 mm) than in the no-epinephrine group (6.30 ± 0.65 mm; P < .001). The intracameral epinephrine injection significantly increased the pupil diameter from 4.65 ± 0.87 to 5.49 ± 0.76 mm (21.61 ± 22.68%; P < .001) and the pupil area from 70.28 ± 24.46 to 96.49 ± 25.24 mm (52.89 ± 63.54%; P < .001). After additional viscomydriasis, there was no difference between groups in pupil diameter (epinephrine vs no-epinephrine group; 6.10 ± 0.77 vs 6.39 ± 0.65 mm; P = .073).A single intracameral injection of 0.015% epinephrine provided immediate and appropriate redilation of pupil in patients with significant miosis after femtosecond laser photodisruption. Intracameral epinephrine is a simple and practical option for pupil redilation in case of miosis during FLACS.

Stability of Adrenaline in Irrigating Solution for Intraocular Surgery

Intraocular irrigating solution containing 1 µg/mL adrenaline is widely used during cataract surgery to maintain pupil dilation. Prepared intraocular irrigating solutions are recommended for use within 6 h. After the irrigating solution is admistered for dilution, the adrenaline may become oxidized, and this may result in a decrease in its biological activity. However, the stability of adrenaline in intraocular irrigating solution is not fully understood. The aim of this study was to evaluate the stability of adrenaline in clinically used irrigating solutions of varying pH. Six hours after mixing, the adrenaline percentages remaining were 90.6%±3.7 (pH 7.2), 91.1%±2.2 (pH 7.5), and 65.2%±2.8 (pH 8.0) of the initial concentration. One hour after mixing, the percentages remaining were 97.6%±2.0 (pH 7.2), 97.4%±2.7 (pH 7.5), and 95.6%±3.3 (pH 8.0). The degradation was especially remarkable and time dependent in the solution at pH 8.0. These results indicate that the concentration of adrenaline is decreased after preparation. Moreover, we investigated the influence of sodium bisulfite on adrenaline stability in irrigating solution. The percentage adrenaline remaining at 6 h after mixing in irrigating solution (pH 8.0) containing sodium bisulfite at 0.5 µg/mL (concentration in irrigating solution) or at 500 µg/mL (concentration in the undiluted adrenaline preparation) were 57.5 and 97.3%, respectively. Therefore, the low concentration of sodium bisulfite in the irrigating solution may be a cause of the adrenaline loss. In conclusion, intraocular irrigation solution with adrenaline should be prepared just prior to its use in surgery.

Phacoemulsification without preoperative topical mydriatics: induction and sustainability of mydriasis with intracameral mydriatic solution

Context:

Intracameral mydriatic solution can eliminate the disadvantages of repeated eye drop instillation regimen and provide adequate mydriasis for phacoemulsification with added advantages.

Aims:

Evaluating the role of intracameral irrigating solution (0.5% lignocaine + 0.001% epinephrine) in initiating and maintaining the pupillary mydriasis during phacoemulsification. Secondary aims were to observe the effect of surgical time, nucleus density and ultrasound time on mydriasis during the procedure.

Settings and Design:

The study is a prospective interventional case series, conducted at tertiary care institution.

Materials and Methods:

Thirty patients underwent phacoemulsification under topical anesthesia for visually significant cataract. Pupillary dilatation was achieved by intracameral irrigation of mydriatic solution alone. Pupillary diameter was measured serially during surgery and ultrasound time and total surgical time were noted.

Statistical Analysis Used:

Paired samples student–t test was done to compare means. Spearman correlation coefficient was used to study the effect of various parameters on mydriasis.

Results:

Thirty eyes completed the study. The pupil size increased from 2.1 mm (Range 2-3.5 mm SD ± 0.32) to 6.9 mm (Range 5-9 mm SD ± 1.02) in 30 seconds time after intracameral mydriatic solution delivery, and was 7.0 mm (Range 3.5 - 9 mm SD ± 0.20) at the end of surgery. Duration of surgery, grade of nucleus and ultrasound time had statistically insignificant effect on mydriasis.

Conclusions:

Intracameral solution containing 0.5% lignocaine and 0.001% epinephrine provides rapid mydriasis which is adequate for safe phacoemulsification and is unaffected by other parameters.

Interaction of intravitreal combination drugs and the effect on the targeted site

BACKGROUND

After evaluating experimentally the diffusion processes in the retina using peroxidase as a tracer material (previously published work), we found that junctional complexes of the retinal pigment epithelium and retinal capillaries were the major impediment to free diffusion between the retina and choroidal-retinal blood vessels. These experiments indicated that to achieve high therapeutic concentrations of medications inside the eye, it was necessary to administer them by intravitreal injection. Soon after initial experimental work the necessity of combining antibiotics or antibiotics with steroids became obvious. As the use of intravitreal injection grew over the last 2 decades, so did the concept of combination therapy.

METHODS

This review describes potential causes of drug-drug interaction and the rationale for combination therapy when injected into the vitreous cavity, encompassing publications between 1971 and 2008.

RESULTS

We describe the conditions that can cause physical-chemical interactions between the medications and the need for combination therapy for treatment of various intraocular disease processes.

CONCLUSIONS

The intravitreal injection of medication and their combinations has become a part of standard care for many diseases of the retina and choroid. This article reviews the potential interaction of nontoxic doses of medications when injected simultaneously in the vitreous cavity, and disease processes that are now treated with these combination therapies.

Development of toxic anterior segment syndrome immediately after uneventful phaco surgery

Purpose

We report on 15 cases of suspected toxic anterior segment syndrome after uneventful phaco surgery.

Methods

We retrospectively reviewed the charts of patients who had developed toxic anterior segment syndrome (TASS) after uneventful phacoemulsification for senile cataracts between April and December of 2005. Clinical features and all possible causes were investigated including irrigating solutions or drugs, surgical instruments or intraocular lenses, sterilization techniques for instruments, or any other accompanying disease.

Results

The patients consisted of 2 males and 13 females with an average age of 64.7±10.9 years. Five different surgeons had performed their phaco surgeries. No abnormal preoperative or operative findings were reported. Nevertheless, all 15 patients developed a moderate degree of corneal edema. Ordinary treatments were not helpful. We suspect that lack of sterilization resulted in the development of the syndrome, because after ethylene oxide gas sterilization was replaced with autoclaving, no such incidents have occurred.

Conclusions

Toxic anterior segment syndrome requires special attention and thorough management, including sterilization of reused surgical instruments.

Toxic endothelial cell destruction syndrome after intraocular lens repositioning with intracameral epinephrine

A 66-year-old Chinese man developed corneal endothelial decompensation after intraocular lens (IOL) repositioning using intracameral epinephrine was performed. The presentation was compatible with toxic endothelial cell destruction syndrome, which is caused by prolonged, direct exposure of the corneal endothelium to relatively high concentrations of intracameral epinephrine. Despite its effective and immediate mydriatic effect, intracameral epinephrine is not recommended for intraoperative mydriasis in procedures such as IOL repositioning or secondary IOL implantation in which minimal irrigating solution is used.

The human corneal endothelium: new insights into electrophysiology and ion channels

The corneal endothelium is a monolayer that mediates the flux of solutes and water across the posterior corneal surface. Thereby, it plays an essential role to maintain the transparency of the cornea. Unlike the epithelium, the human endothelium is an amitotic cell layer with a critical cell density and the risk of corneal decompensation. The number of endothelial cells subsequently decreases with age. Moreover, the endothelial cell loss is accelerated after various impairments such as surgical trauma (e.g. cataract extraction) and following corneal transplantation. This cell loss is associated with programmed cell death (apoptosis) and changed ion channel activity. However, little is known about the electrophysiology and ion channel expression (in particular Ca2+ channels) in corneal endothelial cells. This article reviews our current knowledge about the electrophysiology of the corneal endothelium. It highlights ion channel expression, which may have a major role in corneal cell physiology and pathological events. A better understanding of the (electro)physiological function of the cornea may lead to the development of clinical relevant new therapeutic and preventive measures.

Presumed herpetic endotheliitis following phacoemulsification surgery*

The authors present an observational case series. Three cases of presumed herpetic endotheliitis presented as cases of pseudophakic bullous keratopathy many years after successful phacoemulsification surgery. All patients had reduction of vision in the involved eye, corneal oedema and secondary glaucoma. The patients were treated with medical therapy consisting of topical corticosteroids, antiviral and antiglaucoma drugs. Resolution of corneal oedema, control of glaucoma and restoration of visual acuity were achieved in all cases. Specular microscopy performed thereafter demonstrated relatively normal endothelial cell counts. The authors conclude that pseudophakic bullous keratopathy occurring after phacoemulsification surgery may be caused by herpetic endotheliitis.

Nonhypotensive autonomic agents in veterinary ophthalmology

The parasympathetic and sympathetic divisions of the autonomic nervous system are involved in homeostatic control of a wide variety of ocular functions, including accommodation, pupillomotor control, lacrimation, eyelid position, and aqueous humor production. Familiarity with the functional anatomy of the autonomic nervous system is paramount to the understanding and application of the large number of autonomic drugs used in veterinary ophthalmology. The cholinergic and adrenergic agents discussed in this article are commonly employed to facilitate routine ophthalmic examination, in the diagnosis of autonomic dysfunction, and in the treatment of a variety of ocular diseases.

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.

Effects of intraocular epinephrine on the corneal endothelium of rabbits

Epinephrine is frequently used in the phacoemulsification to dilate pupils. To determine the effects of different concentration of epinephrine on the corneal endothelial cells, twenty-eight rabbit eyes were equally divided into four groups. Solutions, which contained normal saline, 1:1000 epinephrine, 1:5000 epinephrine and 1:10000 epinephrine respectively, were injected into the anterior chambers of the eyes of four groups of rabbits. In vivo morphological changes of corneal endothelium and changes of thickness were checked with specular microscopy. In vitro morphological evaluation of corneal endothelium was observed in excised corneal buttons stained with alizarin red with trypan blue, and with scanning electron microscopy. Our results showed that there was no significant difference in cell density and corneal thickness among the four groups. Alizarin red with trypan blue stain and SEM exam revealed smooth and distinct cell borders of endothelial cells in each group. Intracameral injection of epinephrine does not produce toxic effect on corneal endothelial cells in rabbits.

Maintenance of mydriasis with one bolus of epinephrine injection during phacoemulsification

Surgically-induced miosis commonly occurs during cataract extraction surgery, complicating removal of lens cortex and placement of a posterior chamber intraocular lens. To maintain intraoperative mydriasis, one bolus of epinephrine injection was used in our study. The pupillary response to various doses of intracameral epinephrine (0.1 ml of 1:25,000, 1:50,000, 1:100,000, 1:200,000, 1:400,000) was assessed in 60 consecutive patients. The pupil size was measured just prior to the incision, one min after epinephrine injection, after phacoemulsification and after irrigation/aspiration. There was no significant difference among the mean mydriatic responses to the epinephrine concentrations we tested. The 1:400,000 concentration appeared to be as effective as 1:25,000, but two cases of the 1:400,000 group failed to maintain the pupil diameter after irrigation/aspiration. In addition, we found that blood pressure did not elevate after injection of any concentration of epinephrine. We concluded that one bolus of an extremely dilute concentration of epinephrine (i.e., 1:400,000) injection might be effective in maintaining mydriasis during cataract surgery without systemic side effects.

Corneal opacities after cataract surgery with hypromellose

26 cases of corneal opacity after cataract surgery occurred in a period of 2 weeks in one surgical unit. Cases occurred after a change in source of intraocular hypromellose solution and only among patients in whom the new product had been used.

The effect of intracameral adrenaline infusion on pupil size, pulse rate, and blood pressure during phacoemulsification

Pupillary constriction during phacoemulsification (phaco) and irrigation/aspiration (I/A) is found to be the major cause of iris damage, incomplete cortex removal, posterior capsule rupture, vitreous loss and even posterior lens material dislocation. Cataract surgery is performed more easily if mydriasis can be maintained. Irrigation fluid containing adrenaline is thought to be of benefit in this respect. We designed a prospective study assessing the efficacy and safety of using perioperative adrenaline during phacoemulsification, as an adjunct to preoperative topical mydriatics. Forty-two cases were randomized to receive intraocular irrigation fluid with or without 1:1,000,000 adrenaline, as a study or control group. Diameter of the pupil, pulse rate, systolic and diastolic pressure before-phaco, after-phaco-before-I/A and after-I/A were measured. All of the operations were performed by the same surgeon with the same technique. The pupil size after-phaco-before-I/A was 8.00 mm in the study group and 5.96 mm in the control group. The mydriasis maintained during phacoemulsification was significantly greater in the study group, p < 0.00001. The pupil size after-I/A was 8.03 mm in the study group, and 5.54 mm in the control group. The mydriasis maintained during I/A was significantly greater in the study group, p < 0.00001. Pulse rate and blood pressure in patients of the study group, even those with hypertension, showed no significant fluctuation during the surgery. We concluded that intraocular irrigation with 1:1,000,000 adrenaline was a safe and effective way of maintaining mydriasis during cataract surgery.

Intraocular adrenaline maintains mydriasis during cataract surgery

Cataract surgery is performed more easily if mydriasis can be maintained until the intraocular lens has been inserted. Intraocular irrigation with adrenaline is thought to be of benefit in this respect, and is used by some surgeons but not others. This prospective double blind controlled trial assessed the efficacy and safety of using perioperative adrenaline during extracapsular cataract surgery, as an adjunct to preoperative topical mydriatics. Seventy patients were randomised to receive intraocular irrigation fluid with or without 1:1,000,000 adrenaline. The adrenaline entering the eye through the anterior capsulotomy needle helped to resist the miosis induced by expression of the nucleus (7.1 versus 6.5 mm). The mydriasis maintained during irrigation aspiration was significantly greater in the group receiving adrenaline (6.6 versus 6.0 mm, p < 0.02). Their pupil diameters were also significantly larger at 20 minutes (p < 0.001) and 30 minutes (p < 0.01) into surgery. Pupillary constriction to a diameter of less than 5 mm occurred more frequently in the group not receiving adrenaline. Pulse rate and blood pressure in the 27 patients who had local anaesthesia showed no significant difference between the treatment groups (p > 0.05), and there was no significant variation from baseline (p > 0.05). Intraocular irrigation with adrenaline 1:1,000,000 is a safe and effective means of maintaining mydriasis during cataract surgery.

The effects of denatured sodium hyaluronate on the corneal endothelium in cats

In an in vivo cat model, wide-field specular microscopy and scanning electron microscopy were used to observe whether heat-denatured sodium hyaluronate causes cell damage to the corneal endothelium. The endothelial cell toxicities of various drugs, including 0.01% benzalkonium chloride, 0.2% chlorhexidine digluconate, and 0.5% lidocaine, mixed with intact or untreated sodium hyaluronate were also investigated. Neither heat-denatured nor intact or untreated sodium hyaluronate alone had any adverse effect on the corneal endothelium in cats, whereas 0.01% benzalkonium chloride and 0.2% chlorhexidine digluconate, mixed with sodium hyaluronate, caused substantial endothelial morphologic changes, which resulted in corneal edema. By comparison, 0.5% lidocaine with sodium hyaluronate was found to have minimal effect on the corneal endothelium in cats. These findings indicate that some chemical contaminant with sodium hyaluronate, not heat-denatured sodium hyaluronate, induces an immediate onset of pseudophakic bullous keratopathy.

A bisulfite-free intraocular epinephrine solution

We evaluated a preservative-free, sulfite-free epinephrine solution for potential corneal toxicity, which has been described for sulfite-containing epinephrine solutions. The preservative-free, sulfite-free epinephrine solution did not exhibit endothelial toxicity in three-hour paired human corneal endothelial perfusion at two and four times the concentration of the 1:1,000,000 dilution currently recommended for anterior chamber intraocular irrigating solutions. When epinephrine at a dilution of 1:1,000 was injected directly into the anterior chamber of New Zealand white rabbits, there was markedly less corneal edema induced than there was in previous studies with sulfite-containing solutions of comparably low pH but higher buffer capacities. Although potential toxicity exists for any irrigating solution with a pH outside of the 6.5 to 8.5 pH range, the endothelial toxicity of this solution has been reduced by its low buffer capacity, lack of preservatives, and lack of sulfite, offering an extra margin of safety for intraocular use.

The corneal endothelium

The endothelium is a monolayer of cells on the posterior corneal surface that transports water from the stroma into the anterior chamber. This movement of water counters a natural tendency for the stroma to swell and is necessary to maintain a transparent cornea. Embryologic studies, in particular the demonstration of the derivation of the endothelium from the neural crest, have provided insight into the factors that govern the response of this tissue to disease. In some species the endothelium can regenerate after injury, but in man cellular enlargement is the main mechanism of repair after cell loss. A clinical estimate of endothelial cell density and function is provided by specular microscopy, fluorophotometry and pachymetry. In this paper we review the development, structure and function of the corneal endothelium, and then consider the pathological processes that can affect this tissue.

The effect of epinephrine and benzalkonium chloride on cultured corneal endothelial and trabecular meshwork cells

We evaluated the effect of dipivefrin hydrochloride, epinephrine hydrochloride, epinephrine borate and their respective vehicles with and without the preservative benzalkonium chloride, on the in vitro growth characteristics of human corneal keratocytes, endothelial cells and trabecular meshwork. Epinephrine hydrochloride and borate at low concentrations (0.0002%) significantly inhibited growth of both trabecular meshwork and corneal endothelial cells. Higher concentrations (0.02%) of these same drugs induced the same effect on the growth of keratocytes in vitro. Similar observations were made on the effect of dipivefrin hydrochloride on human corneal cells in vitro. Benzalkonium chloride alone was demonstrated to be responsible for the growth inhibitory effects on trabecular cells. The susceptibility of trabecular meshwork cells in culture to the commonly used ophthalmic preservative benzalkonium chloride is demonstrated.

Effect of inflammation on the corneal endothelial pump and barrier

Corneal thickness is a reflection of endothelial barrier and pump functions. The corneal edema that occurs during intraocular inflammation is a consequence of the breakdown of one or both of these parameters. Results of this study demonstrate that, during intraocular inflammation induced by an intravitreal injection of bovine serum albumin (BSA), the permeability of rabbit corneal endothelia to inulin was increased. By comparison, treatment with oral aspirin and/or subconjunctival triamcinolone acetonide prevented the endothelial barrier breakdown induced by the BSA. Concomitant with the loss of the barrier function, endothelial ouabain binding decreased in the BSA injected eye, indicating a reduction in endothelial Na/K ATPase pump site density. A subconjunctival injection of triamcinolone prevented this decrease in pump sites. The increase in endothelial permeability and the decrease in pump site density correlated with an increase in corneal thickness. It can be concluded that the intraocular inflammation induced by BSA effects corneal edema by both an increase in endothelial permeability and a decrease in Na/K ATPase pump site density. Subconjunctival triamcinolone is effective in preventing this response.

Effect of oxybuprocaine 0.4% in preventing surgically induced miosis

In a group of 68 patients a double-blind study was performed to assess the effect of preoperative oxybuprocaine 0.4% (Dorsacaine, Novesin) eye drops in comparison with a placebo in preventing surgically induced miosis during extracapsular cataract extraction. One drop of oxybuprocaine 0.4% or placebo was instilled 10 and 5 minutes preoperatively. The pupil diameter was recorded at different stages of the operation. It was found that oxybuprocaine reduced the amount of pupil constriction during the operation significantly as compared with the placebo group, facilitating the removal of lens material and the implantation of an intraocular lens. The effect of oxybuprocaine is considered to be due to anaesthetic action on sensory nerves in the eye, which may inhibit the release of a miotic substance.

Complications of vitreous surgery for diabetic retinopathy. II. Postoperative complications

One hundred seventy-nine eyes were analyzed to determine the incidence of postoperative complications after vitrectomy for proliferative diabetic retinopathy. One hundred twenty-nine (72%) of the 179 eyes achieved improved vision, and 117 (65%) were considered visual successes with final vision in the functional range of 5/200 or better. Corneal epithelial defects occurred in 51 eyes (28%), but severe corneal complications were rare, and no eye developed corneal clouding as the sole cause of later visual loss. The lens was retained in 128 eyes (75%), and visually significant lens opacities occurred later in 17% of the phakic eyes. Postoperative iris neovascularization was reduced by not removing the lens, and rubeosis iridis occurred in 15 (13%) of 114 phakic eyes and in 21 (32%) of 65 aphakic eyes (P = 0.012). Vitreous hemorrhage was present in 75% of eyes immediately after surgery and cleared in an average of 6.2 weeks in phakic eyes and 5.4 weeks in aphakic eyes. Fifty-two eyes (29%) had recurrent vitreous hemorrhage after the initial postoperative period. New retinal detachment occurred after surgery in 16% of eyes and was treated successfully in 38%. Reoperations were done in 45 eyes (25%), and 32 (71%) of these were for repair of retinal detachment or removal of nonclearing vitreous hemorrhage. Six eyes (3%) developed phthisis bulbi, and one other eye was enucleated.