Intraoperative intracameral carbachol in phacoemulsification and posterior chamber lens implantation

Prophylaxis against intraocular pressure spikes following uncomplicated phacoemulsification: a systematic-review and meta-analysis

BACKGROUND

To investigate the effect of perioperative intraocular pressure (IOP) lowering medications on controlling postoperative IOP following uncomplicated phacoemulsification.

METHODS

Ovid MEDLINE, EMBASE, and Cochrane CENTRAL databases were searched up until November 2022. Randomised controlled trials (RCTs) that assessed IOP change via applanation tonometry in medicated and control arms following uncomplicated cataract surgery in healthy eyes were included. The primary outcome was the weighted mean difference (WMD) of IOP at 2-8 h, 12-24 h, and 1-7 days postoperatively within each medication class or common fixed-combination formulations. Risk of bias was assessed using the revised risk of bias in randomised trials (RoB-2). Level of evidence was rated using the Grading of Recommendation, Assessment, Development and Evaluation (GRADE) RESULTS: From 702 screened articles, 30 RCTs involving 2986 eyes were included. There was a statistically significant reduction in IOP favouring treatment arms at 2-8 h (WMD = -3.87 mmHg; 95% CI [-4.75, -3.00]; p < 0.001) and 12-24 h (WMD = -2.69 mmHg; 95% CI [-3.36, -2.02]; p < 0.001), with the effect wearing off beyond 1 day (p = 0.18). Between medication classes, the largest effect at both 2-8 h and 12-24 h was observed with intracameral cholinergics or fixed-combination carbonic anhydrase inhibitor-beta-blocker (FCCB) formulations. Conversely, the smallest effect was observed with prostaglandin analogues, alpha-agonists, and topical carbonic anhydrase inhibitors (CAIs).

CONCLUSION

Prophylaxis against acute IOP elevations following uncomplicated cataract surgery is effective. FCCB and intracameral cholinergics are the most effective ocular antihypertensive agents, while alpha-agonists, prostaglandin analogues, and topical CAIs were found to be the least effective. These findings may inform future surgical guidelines.

Cholinergic nervous system and glaucoma: From basic science to clinical applications

The cholinergic system has a crucial role to play in visual function. Although cholinergic drugs have been a focus of attention as glaucoma medications for reducing eye pressure, little is known about the potential modality for neuronal survival and/or enhancement in visual impairments. Citicoline, a naturally occurring compound and FDA approved dietary supplement, is a nootropic agent that is recently demonstrated to be effective in ameliorating ischemic stroke, traumatic brain injury, Parkinson's disease, Alzheimer's disease, cerebrovascular diseases, memory disorders and attention-deficit/hyperactivity disorder in both humans and animal models. The mechanisms of its action appear to be multifarious including (i) preservation of cardiolipin, sphingomyelin, and arachidonic acid contents of phosphatidylcholine and phosphatidylethanolamine, (ii) restoration of phosphatidylcholine, (iii) stimulation of glutathione synthesis, (iv) lowering glutamate concentrations and preventing glutamate excitotoxicity, (v) rescuing mitochondrial function thereby preventing oxidative damage and onset of neuronal apoptosis, (vi) synthesis of myelin leading to improvement in neuronal membrane integrity, (vii) improving acetylcholine synthesis and thereby reducing the effects of mental stress and (viii) preventing endothelial dysfunction. Such effects have vouched for citicoline as a neuroprotective, neurorestorative and neuroregenerative agent. Retinal ganglion cells are neurons with long myelinated axons which provide a strong rationale for citicoline use in visual pathway disorders. Since glaucoma is a form of neurodegeneration involving retinal ganglion cells, citicoline may help ameliorate glaucomatous damages in multiple facets. Additionally, trans-synaptic degeneration has been identified in humans and experimental models of glaucoma suggesting the cholinergic system as a new brain target for glaucoma management and therapy.

Is the 1-day postoperative IOP check needed post uncomplicated phacoemulsification in patients with glaucoma and ocular hypertension?

PURPOSE

To determine whether the 1-day postoperative intraocular pressure (IOP) check following routine uncomplicated phacoemulsification is necessary in patients with pre-existing glaucoma and ocular hypertension (OHT), if acetazolamide prophylaxis is used. To investigate the practice of U.K. glaucoma specialists in IOP rise prophylaxis and follow-up regimes.

PATIENTS AND METHODS

The IOP 1-day postoperatively was analysed against the last recorded IOP before phacoemulsification in a cohort of patients with glaucoma or OHT who underwent uncomplicated phacoemulsification cataract surgery between December 2009 and September 2012, where it was routine practice to give acetazolamide postoperatively. U.K. and Eire Glaucoma Society members were surveyed via an online questionnaire to analyse practice among U.K. glaucoma specialists.

RESULTS

One hundred and seven eyes were studied: 99 with glaucoma and 8 with OHT. The mean IOP change was -0.8 mm Hg with only two eyes measuring >30 mm Hg postoperatively (2%). Both these eyes received 750 mg acetazolamide. Eighteen (17%) eyes had an IOP rise of at least 30%. In the survey of practice there were 65 respondents. Twenty-one (32%) respondents did not use IOP prophylaxis. Only 17 (26%) of respondents routinely reviewed their patients 1-day postoperatively.

CONCLUSION

Our prophylactic acetazolamide regime does not completely eliminate the risk of an IOP >30 mm Hg on day 1 post routine phacoemulsification in glaucoma/OHT patients. Patients with pre-existing glaucoma, despite acetazolamide prophylaxis, will require IOP management decisions on the first postoperative day after uncomplicated phacoemulsification surgery. U.K. expert practice is non-uniform with regard to IOP prophylaxis, and the 1-day review, and further discussion and formulation of consensus appears necessary.

Effect of intracameral carbachol in phacoemulsification surgery on macular morphology and retinal vessel caliber

OBJECTIVE

To investigate the effects of intracameral carbachol in phacoemulsification surgery on central macular thickness (CMT), total macular volume (TMV) and retinal vessel caliber (RVC).

MATERIALS AND METHODS

In this prospective consecutive case series, 82 patients underwent uneventful phacoemulsification and in-the-bag intraocular lens implantation. Unlike patients in the control group (43 eyes), patients in the study group (42 eyes) were injected with intracameral 0.01% carbachol during surgery. Spectral-domain optical coherence tomography (OCT) was used to analyze the parameters of CMT, TMV and RVC.

RESULTS

On the first postoperative day, mean CMT and TMV decreased markedly in the carbachol group, though these values did not change significantly in the control group. During follow-up visits, no statistically significant differences between the groups occurred regarding changes in mean CMT (p = 0.25, first day; p = 0.80, first week; p = 0.95, first month). However, change in mean TMV between groups on the first postoperative day was statistically significant (p = 0.01, first day; p = 0.96, first week; p = 0.68, first month). RVC values were similar on the preoperative and postoperative first days in both groups (p > 0.05).

DISCUSSION

Results suggest that the effect of intracameral carbachol on macular OCT is related to pharmacological effects, as well as optic events (e.g. miosis).

CONCLUSION

Intracameral carbachol given during cataract surgery decreases macular thickness and volume in the early postoperative period but does not exert any gross effect on RVC.

Agents for intraocular surgery

No single viscoelastic material has all the properties required for every surgical procedure. Ophthalmic surgeons should be familiar with the advantages and disadvantages of several viscoelastics and realize the limitations encountered if the surgeon chooses to rely on a single viscoelastic. It is possible in the future that newer viscoelastics may become available offering aspects of cohesive and dispersive properties that make them easy to remove and not associated with postoperative hypertension. Investigation into other types of viscoelastic materials, such as poly-acrylamide (Orcolon) [33,51,52], human collagen [33,53], polytriethylene-glycol monomethacrylate, and polyglycerol monomethacrylate [48], may result in the availability of synthetic viscoelastic materials. Rethinking how we use viscoelastics may also be indicated. The approach of a single or repeat instillation of a viscoelastic only to have it aspirated during the procedure could be modified by using a continuous infusion ofa dilute viscoelastic [54]. One study diluted hyaluronic acid to a concentration of 0.06% to 0.12% and maintained continuous infusion of the viscofluid through the PE irrigation line [54]. It has been suggested that this may reduce turbulence and improve tissue protection [54].

Efficacy of brimonidine 0.2% in controlling acute postoperative intraocular pressure elevation after phacoemulsification

PURPOSE

To determine the efficacy of brimonidine tartrate 0.2% drops given 2 times a day in reducing intraocular pressure (IOP) spikes during the first 24 hours after phacoemulsification cataract surgery.

SETTING

Department of Ophthalmology, General Hospital of Patras Agios Andreas, Patras, Greece.

METHODS

In this prospective double-blind placebo-controlled study, 1 eye of 40 consecutive normotensive cataract patients having small-incision cataract surgery was randomized into 1 of 2 treatment arms. Twenty patients received a placebo (artificial tears) and 20 patients received brimonidine tartrate 0.2% drops 2 times a day the day before and the day of surgery. Diurnal IOP variation was the primary efficacy variable; IOP was measured at baseline, before surgery, and 4, 6, 12, and 24 hours postoperatively.

RESULTS

The placebo group had higher IOPs at every time point after surgery. Peak elevation of IOP occurred 6 hours after surgery. The mean IOP in the placebo group (27.71 mm Hg +/- 3.75 [SD]) was statistically significantly higher than in the brimonidine group (21.45 +/- 1.32 mm Hg) (P<.001). A major IOP rise (>/=20 mm Hg above baseline IOP) occurred in 1 patient (5%) in the placebo group who required emergency hypotensive therapy. Twenty-four hours after surgery, 11 eyes (55%) in the brimonidine group and 4 eyes (20%) in the placebo group had an IOP lower than baseline.

CONCLUSION

Prophylactic treatment with brimonidine tartrate 0.2% 2 times a day for 2 days was effective in reducing IOP peaks throughout the first 24 hours after phacoemulsification surgery.

Effect of dorzolamide and latanoprost on intraocular pressure after small incision cataract surgery

PURPOSE

To evaluate the effect of dorzolamide 2% and latanoprost 0.005% on intraocular pressure (IOP) after small incision cataract surgery.

SETTING

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

METHODS

This prospective study comprised 102 eyes of 102 consecutive patients scheduled for small incision cataract surgery. The patients were assigned preoperatively to 1 of 3 groups of 34 each: dorzolamide, latanoprost, and control (no treatment). One drop of the assigned medication was instilled immediately after surgery. Intraocular pressure was measured preoperatively and 6 and 20 to 24 hours postoperatively.

RESULTS

Six hours after surgery, the mean increase in IOP was 1.9 mm Hg +/- 3.9 (SD) in the dorzolamide group (P = .004 versus control), 2.2 +/- 3.0 mm Hg in the latanoprost group (P = .005 versus control), and 4.8 +/- 5.2 mm Hg in the control group. Twenty to 24 hours postoperatively, IOP decreased a mean of -0.9 +/- 3.5 mm Hg in the dorzolamide group (P = .012 versus control) and increased a mean of 0.3 +/- 3.6 mm Hg in the latanoprost group (P = 0.24 versus control) and 1.3 +/- 4.2 mm Hg in the control group. One eye in the dorzolamide group, 1 eye in the latanoprost group, and 4 eyes in the control group had an IOP of 30 mm Hg or higher 6 hours postoperatively.

CONCLUSION

Six hours postoperatively, dorzolamide and latanoprost were effective in reducing the IOP increase after small incision cataract surgery; however, at 20 to 24 hours, only dorzolamide was effective. Neither drug prevented IOP spikes of 30 mm Hg or higher.

The placebo effect

Placebos have been traditionally regarded as deceptive therapies and have not been understood in the broader context of social symbols and of interpersonal factors that surround the healing process itself. Although the power of inert substances to heal is well recognized, the placebo effect also influences the outcome of conventional therapies. The role of the placebo in modern medicine is poorly defined because of a lack of a common understanding of what the placebo effect is and because of the negative connotions associated with its use. The response rate to placebo varies by illness. The natural course of disease and patient or physician bias can be misinterpreted as a placebo response. In research, the placebo effect is therapeutic noise to be removed by placebo-controlled trials. Few studies are designed to measure the placebo response rate directly. Placebos are a reminder of how little is known about mind-body interaction. The placebo effect may be one of the most versatile and underused therapeutic tools at the disposal of physicians.

Effect of intracameral carbachol on intraocular pressure following clear corneal phacoemulsification

PURPOSE

To investigate the effect of 0.01% carbachol on early intraocular pressure (IOP) after cataract extraction with phacoemulsification.

METHODS

Fifty-one patients who underwent cataract extraction with phacoemulsification and intraocular lens implantation were prospectively randomly assigned to one of two groups. Twenty-seven patients were given 0.5 ml carbachol intracamerally (carbachol group); the other 24 patients were given the same amount of balanced salt solution intracamerally (control group). IOPs were measured by Goldmann applantation tonometry on the day before surgery, and at 8 h, 24 h and 7 days post-operatively.

RESULTS

There was no difference between the mean IOPs of the groups pre-operatively (p > 0.5). All the mean post-operative IOP values of the carbachol group were lower than those of the control group. At 8 and 24 h post-operatively the mean IOP was 12.4 +/- 3.4 mmHg and 13.1 +/- 4.5 mmHg respectively in the carbachol group, 19.4 +/- 6.4 mmHg and 17.2 +/- 4.2 mmHg respectively in the control group. The differences were significant (p < 0.04 and p < 0.05). There was no significant difference between the values at 7 days post-operatively (p > 0.8). An IOP greater than 25 mmHg was recorded at 8 h and 24 h post-operatively in 8 (33%) and 4 (17%) of the control group and in 1 (4%) and 1 (4%) of the carbachol group. All the IOPs were 20 mmHg or lower in both groups at 7 days post-operatively.

CONCLUSION

Patients treated with intracameral carbachol following uncomplicated clear corneal phacoemulsification and posterior chamber intraocular lens implantation demonstrate lower early post-operative IOP.