An intraocular irrigation solution containing niacinamide and its application

Abstract

The present invention discloses an intraocular irrigation solution containing niacinamide. Niacinamide serves as an active substance in the intraocular irrigation solution, which has the effects of improving the function of corneal endothelial cells, inhibiting cell apoptosis and cell fusion, and improving the mitochondrial damage condition, thereby alleviating or inhibiting corneal edema, reduction of corneal endothelial cells, abnormal corneal transparency, abnormal corneal thickness, abnormal corneal endothelial cell density, abnormal corneal endothelial cell morphology, and abnormal expression of corneal endothelial cell functional proteins caused by ultrasonic stimulation, heat stimulation or oxidative damage to corneal endothelial cells during phacoemulsification surgery.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine, and particularly relates to an intraocular irrigation solution containing nicotinamide and its application. Background Art

[0002] Cataract is the leading cause of blindness in the world. At present, most cataract surgeries are completed through phacoemulsification surgery, that is, using high-intensity ultrasonic energy to break and emulsify the cloudy lens. With the progress of surgical equipment and the development of technology, the indications of phacoemulsification have been extended to mature cataracts with harder lens nuclei, so greater phacoemulsification energy and time are required. However, excessive phacoemulsification energy, lens nucleus fragments, local temperature increase, etc. will all damage corneal endothelial cells (CECs), cause a significant decrease in the number of CECs, and then lead to corneal edema, and even corneal endothelial decompensation, and severe cases require corneal transplantation. So far, there is no effective, convenient and widely promoted protection strategy for CECs during cataract phacoemulsification in clinical practice. There are research reports that during phacoemulsification, part of the corneal endothelial damage is caused by oxidative stress. As a strong reducing agent, hydrogen (H2) dissolved in the irrigation solution can reduce corneal endothelial damage during phacoemulsification, but H2 has strong penetrability and is volatile, and it is difficult to be retained in the irrigation solution for a long time. There are also studies showing that adding glutamine to the irrigation solution can protect CECs damaged by high intraocular pressure, but the effect after phacoemulsification has not been reported. At present, the BSS PLUS irrigation solution launched by Alcon shows a role in protecting CECs, but its price is expensive. There is still a lack of effective and low-cost products to reduce corneal damage during phacoemulsification. Summary of the Invention

[0003] In the first aspect of the present invention, to solve the deficiencies of the prior art, there is provided the use of nicotinamide in preventing or improving oxidative stress damage of corneal endothelial cells; or the use of nicotinamide in preparing a drug or medical device for protecting corneal endothelial cells during phacoemulsification or corneal transplantation.

[0004] Preferably, as an active substance, nicotinamide has the effects of improving endothelial cell function, inhibiting cell apoptosis and cell fusion, and improving the mitochondrial damage condition.

[0005] Preferably, protecting corneal endothelial cells includes alleviating or inhibiting the damage of corneal endothelial cells caused by ultrasonic stimulation, heat stimulation or oxidative stimulation, including corneal edema, reduction of corneal endothelial cells, abnormal corneal transparency, abnormal corneal thickness, abnormal corneal endothelial cell density, abnormal corneal endothelial cell morphology, and abnormal expression of corneal endothelial cell functional proteins.

[0006] Optionally, the phacoemulsification process includes phacoemulsification surgery or phacoemulsification treatment. Preferably, the phacoemulsification process is intracapsular phacoemulsification surgery.

[0007] Preferably, the intracapsular phacoemulsification surgery is applied to individuals with cataracts, including senile cataracts and diabetic cataracts.

[0008] Optionally, the individual is a vertebrate, preferably a mammal, including humans, non-human primates, mice, rats, dogs, cats, horses or cows.

[0009] Optionally, the drug or medical device is an electrolyte solution, a balanced salt solution, a cell culture medium, or an intraocular irrigation solution.

[0010] Preferably, the concentration of nicotinamide in the drug is not less than 1 mM / l. More preferably, the concentration of nicotinamide in the drug is 1-5 mM / l. More preferably, the concentration of nicotinamide in the drug is not less than 2.5 mM / l. More preferably, the concentration of nicotinamide in the drug is 2.5-5 mM / l.

[0011] In the second aspect of the present invention, there is provided an intraocular irrigation solution containing nicotinamide, including nicotinamide and an electrolyte solution; or, nicotinamide and a balanced salt solution; or, nicotinamide and a cell culture solution.

[0012] Preferably, the concentration of nicotinamide in the intraocular irrigation solution is not less than 1 mM / l. More preferably, the concentration of nicotinamide is not less than 2.5 mM / l. More preferably, the concentration of nicotinamide is 1-5 mM / l. More preferably, the concentration of nicotinamide is 2.5-5 mM / l.

[0013] In the third aspect of the present invention, there is provided the application of the above-mentioned intraocular irrigation solution containing nicotinamide in the phacoemulsification process.

[0014] Optionally, the phacoemulsification process includes phacoemulsification surgery or phacoemulsification treatment. Preferably, the phacoemulsification process is intracapsular phacoemulsification surgery.

[0015] Preferably, the intracapsular phacoemulsification surgery is applied to individuals with cataracts, including senile cataracts and diabetic cataracts.

[0016] Optionally, the individual is a vertebrate, preferably a mammal, including humans, non-human primates, mice, rats, dogs, cats, horses or cows.

[0017] Preferably, nicotinamide acts as an active substance in the intraocular irrigation solution, having the effects of improving endothelial cell function, inhibiting cell apoptosis and cell fusion, and improving the mitochondrial damage condition, thereby realizing the function of protecting corneal endothelium.

[0018] Optionally, the methods for protecting corneal endothelial cells include alleviating or inhibiting the damage to corneal endothelial cells caused by ultrasonic stimulation, heat stimulation or oxidative stress, including corneal edema, reduction of corneal endothelial cells, abnormal corneal transparency, abnormal corneal thickness, abnormal corneal endothelial cell density, abnormal corneal endothelial cell morphology, and abnormal expression of corneal endothelial cell functional proteins.

[0019] It should be understood that the content described in the Summary of the Invention section is not intended to limit the key or important features of the embodiments of the present invention, nor to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description.

[0020] The present invention has the following beneficial effects:

[0021] There are nearly 200 million cataract patients and 141 million diabetic patients in our country. When diabetic cataract patients undergo cataract surgery, it will cause varying degrees of damage to corneal endothelial cells, which will further lead to corneal edema and opacity. In severe cases, it can cause decompensation of corneal endothelial cell function. The present invention can be prepared by adding nicotinamide to conventional electrolyte solutions, balanced salt solutions, and cell culture media. It is convenient to operate and low in price. It will greatly protect corneal endothelial cells, improve the postoperative visual acuity improvement level of cataract patients, and prevent the occurrence of decompensation lesions of corneal endothelial cells (corneal endothelial blindness), which is of great significance to the social development of our country and the improvement of people's living standards. Brief Description of the Drawings

[0022] Figure 1 Schematic diagrams of different corneal endothelial cell damage models and analysis and verification of the mechanism of endothelial damage caused by phacoemulsification surgery.

[0023] Figure 2 Showing the protective effect of different concentrations of nicotinamide on corneal endothelial cells cultured in vitro during phacoemulsification stimulation. (A) Photographs of corneal endothelial cells after 1 hour and 24 hours of phacoemulsification stimulation; (B) Fold change in corneal endothelial cell density after treatment with different concentrations of nicotinamide for 24 hours.

[0024] Figure 3 Showing the corneal transparency and thickness conditions of rabbits after phacoemulsification surgery with different energies and different times.

[0025] Figure 4 Showing the protective effect of different concentrations of nicotinamide on corneal transparency and thickness of rabbits during phacoemulsification surgery in the animal experiment of Example 4. (A) Gross images and OCT photographs of the cornea 2 days after phacoemulsification surgery; (B) Statistical results of corneal thickness 2 days after phacoemulsification surgery.

[0026] Figure 5Show the photos of the effects of nicotinamide on the gross appearance and OCT of rabbit corneas at different time points after phacoemulsification surgery in the animal experiment of Example 4.

[0027] Figure 6 Show the changing trends of intraocular pressure and corneal thickness of rabbit corneas after nicotinamide treatment combined with phacoemulsification surgery in the animal experiment of Example 4. (A) The changing graph of rabbit intraocular pressure; (B) The changing graph of rabbit corneal thickness.

[0028] Figure 7 Show the protective effect of nicotinamide (NAM) treatment on rabbit corneal endothelial cells after phacoemulsification surgery in the animal experiment of Example 4. (A) Images of corneal endothelial cells at 7 days after surgery shown by confocal microscopy of corneal endothelium, and the red arrows show enlarged endothelial cells; (B) Statistical analysis of the multiple comparison of corneal endothelial cell density at 7 days after surgery under the conditions of adding or subtracting NAM (**P<0.01); (C) Detection of the effects of NAM treatment on the expression and distribution of the corneal endothelial cell marker functional genes ZO1 and ATP1A1 by corneal endothelial sheet staining at 7 days after surgery.

[0029] Figure 8 Show the analysis of the protective effect of an intraocular irrigation fluid containing NAM on corneal endothelial cell damage in patients after clinical phacoemulsification surgery. (A) Gross appearance pictures and OCT pictures of the patient's cornea before surgery, 1 day after surgery, and 30 days after surgery; (B) The changing trend of corneal thickness in the patient's cornea within 1 month after surgery; (C) The changing trend of corneal endothelial cell density in the patient's cornea within 1 month after surgery.

[0030] Figure 9 Show the conditions of corneal transparency (A) and thickness (B) of rabbits after using intraocular irrigation fluids containing glutamine (Gln) and NAM respectively during phacoemulsification surgery in a rabbit model. Detailed implementation manners

[0031] The inventors have previously published an article (Nicotinamide inhibits corneal endothelialmesenchymal transition and accelerates wound healing, Zongyi Li et al. Exp EyeRes. 2019) reporting that 5 mM nicotinamide (niacinamide) promotes the proliferation of human corneal endothelial cell lines and inhibits TGF-β-induced endothelial-mesenchymal transition; meanwhile, 2.5 mM nicotinamide can promote the regeneration and repair of mechanically removed rabbit corneal endothelial cells. The animal model of corneal endothelial cell mechanical removal injury is established by Figure 1A modeling method for corneal endothelial cell removal in half of the cornea (shaded area) as shown, resulting in the loss of corneal endothelial cells and subsequent corneal edema and opacity. Among them, the function of adding nicotinamide to the ocular surface is to inhibit the endothelial-mesenchymal transition of regenerated cells and promote the proliferation of rabbit corneal endothelial cells to play a reparative role. For the specific mechanism research, please refer to the discussion in the article. When considering using drugs to protect corneal endothelial cells against mechanical tearing injury, drugs with the ability to promote cell migration, inhibit mesenchymal transition, or promote proliferation will be selected, such as Y27632, FGF10, NAM, etc.

[0032] However, it is completely different from the mechanical tearing injury in the previous research. In cataract surgery, phacoemulsification equipment is used to remove the lens, which subsequently causes corneal endothelial damage. The main injury mechanism is the stimulation and oxidative stress injury caused by various factors such as ultrasound and / or heat stimulation to corneal endothelial cells ( Figure 1 ). After corneal transplantation, oxidative stress injury also exists. When considering using drugs to protect corneal endothelial cells against oxidative stress injury, drugs with the effect of inhibiting oxidative stress will be selected, such as vitamin C, glutathione, ascorbic acid, metal ion chelators, etc.

[0033] The inventors' research found that the main reasons for the supra-physiological decrease in corneal endothelial cell density caused by cataract surgery mainly include cell apoptosis, cell fusion, and mitochondrial damage caused by oxidative stress. This is a completely new discovery in this field and a new mechanism of action that is completely different from the previous research. As Figure 1 shown, in vitro transcriptomic analysis of corneal endothelial cells treated with cataract surgery equipment found that ultrasound stimulation would cause a decrease in the expression of genes related to mitochondrial function and an increase in the expression of apoptosis-related genes mediated by mitochondria ( Figure 1 B). Immunofluorescence staining of corneal endothelial cells treated surgically for 7 days showed that cataract surgery alone would promote cell fusion and generate multinucleated giant cells; combined with nicotinamide, it could significantly inhibit cell fusion and maintain the single-cell state, thereby protecting the number of corneal endothelial cells ( Figure 1 C). In addition, cataract surgery alone would increase the mitochondrial oxidation level Mitosox; combined with nicotinamide, it could significantly inhibit the Mitosox level and increase the expression level of mitochondrial membrane protein TOM20, suggesting that nicotinamide protects the mitochondrial function of corneal endothelial cells ( Figure 1 D). Based on the research results, the inventors selected and verified nicotinamide as a drug for protecting corneal endothelial cells during cataract surgery through the functional analysis and prediction of small molecule drugs, and confirmed that it has the effect of protecting the density and function of corneal endothelial cells by inhibiting cell apoptosis and cell fusion and improving mitochondrial damage.

[0034] Nicotinamide is a known compound. However, there has been no precedent so far for using it as a drug for preventing corneal injury in combination with an intraocular irrigation solution. The use of nicotinamide as a drug for protecting corneal endothelium in cataract surgery in the present invention is also the first time.

[0035] During cataract surgery, an intraocular irrigation solution is used for assistance, and the time is generally 5 - 30 minutes. In order to provide protection for corneal endothelial cells during the surgery, adding an active protective molecule to the intraocular irrigation solution is one of the best choices. Therefore, in the present invention, nicotinamide is added to a conventional intraocular irrigation solution (such as an electrolyte solution, a balanced salt solution), which is convenient to operate and low in price.

[0036] However, the concentration of nicotinamide used needs to be strictly controlled. If the concentration is too low, the expected protective effect cannot be achieved; if the concentration is too high, it will cause cell damage and affect the function and survival of endothelial cells. Through in vitro cell experiments and in vivo animal experiments, the present invention has found the appropriate concentration of nicotinamide in terms of protecting the density and function of corneal endothelial cells.

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0038] Unless otherwise specified, all technical and scientific terms and abbreviations used herein have the meanings commonly understood by those of ordinary skill in the art in the field of the present invention or the field where the term is applied. Although any substances or materials similar to or equivalent to those disclosed herein can be used in the implementation of the present invention, the preferred substances or materials are described herein.

[0039] Unless otherwise specified, all scientific and technical terms used in this application have the meanings commonly used in the art. As used in this application, the following words or phrases have the specified meanings.

[0040] The singular forms "a", "an", and "the" used in the specification and the appended claims include plural referents unless the context clearly dictates otherwise.

[0041] As used herein, "individual" and "patient" have the same meaning and refer to a vertebrate, preferably a mammal. Mammals can be humans, non-human primates, mice, rats, dogs, cats, horses or cows, but are not limited to these examples. Mammals other than humans can be advantageously used as patients representing a cataract surgery model. Preferably, the patient is a human. Such patients typically suffer from or are predisposed to a disorder that can be prevented or treated by administering the above-mentioned traditional Chinese medicine composition or the above-mentioned preparation of the present invention.

[0042] As used herein, "phacoemulsification" refers to a process in which, under the action of ultrasonic energy, two (or more) immiscible liquids are mixed evenly to form a dispersion system, in which one liquid is evenly distributed in the other liquid to form an emulsion.

[0043] Example 1 Preparation of an intraocular irrigation solution containing nicotinamide (NAM)

[0044] Nicotinamide is added to a pharmaceutically acceptable solvent or culture medium, such as cell culture medium, electrolyte solution or balanced salt solution, to obtain an intraocular irrigation solution containing nicotinamide (anterior chamber perfusion solution for intraocular surgery). Those skilled in the art can routinely select the solvent or culture medium according to needs and obtain it through commercial purchase.

[0045] In some embodiments, a compound electrolyte intraocular irrigation solution (Shike, Shenyang Xingqi Eye Pharmaceutical Co., Ltd.) is used. The compound electrolyte intraocular irrigation solution is prepared according to the instructions (Part I of the compound electrolyte intraocular irrigation solution: 480 ml of sterile solution, the main components include sodium chloride, potassium chloride, magnesium sulfate, sodium bicarbonate; Part II: 20 ml of sterile solution, the main components include glucose, calcium chloride). The solution in Part II is transferred into the solution in Part I with a sterile syringe, and the two are gently shaken to mix them evenly to obtain a compound electrolyte intraocular irrigation solution. Then, nicotinamide is added to the compound electrolyte intraocular irrigation solution to obtain intraocular irrigation solutions with different addition amounts of nicotinamide.

[0046] In other embodiments, nicotinamide injection (specification: 1 ml: 100 mg per vial, Guangzhou Baiyunshan Mingxing Pharmaceutical Co., Ltd.) is used. 3 vials of nicotinamide injection (300 mg) are taken and added to the intraocular irrigation solution, and the final volume is made up to 492 ml to prepare an intraocular irrigation solution containing 5 mM nicotinamide; 1 vial of nicotinamide injection (100 mg) is taken and added to the intraocular irrigation solution, and the final volume is made up to 328 ml to prepare an intraocular irrigation solution containing 2.5 mM nicotinamide; 1 vial of nicotinamide injection (100 mg) is taken and added to the intraocular irrigation solution, and the final volume is made up to 820 ml to prepare an intraocular irrigation solution containing 1 mM nicotinamide.

[0047] In some other embodiments, a culture medium or balanced salt solution is used. 1.22 g of nicotinamide powder (purchased from ThermoFisher Scientific Inc.) is dissolved in 10 ml of PBS buffer to prepare a 1 M nicotinamide stock solution. Then, it is diluted to the required concentration with a culture medium or balanced salt solution as needed. For example, it is diluted at a ratio of 1:1000 to obtain a culture medium / balanced salt solution containing 1 mM nicotinamide; diluted at a ratio of 1:400 to obtain a culture medium / balanced salt solution containing 2.5 mM nicotinamide; diluted at a ratio of 1:200 to obtain a culture medium / balanced salt solution containing 5 mM nicotinamide.

[0048] Example 2 Protective effect of different concentrations of nicotinamide on corneal endothelial cells stimulated by phacoemulsification - in vitro cell experiment

[0049] Construct an in vitro cell model treated with phacoemulsification: Select the human corneal endothelial cell line B4G12 for culture, and inoculate it into a 48-well cell culture plate according to a cell density of 1×10 5 After culturing for 24 hours, prepare for the experiment.

[0050] Experimental grouping:

[0051] Control group: Use a complete cell culture medium for corneal endothelial cells (purchased from Creative Bioarray);

[0052] Experimental treatment groups: (1) Complete cell culture medium containing 1 mM nicotinamide; (2) Complete cell culture medium containing 2.5 mM nicotinamide; (3) Complete cell culture medium containing 5 mM nicotinamide.

[0053] Phacoemulsification treatment: Aspirate the culture medium in the cell culture plate and replace it with a balanced salt solution. Prepare and debug the Oertli phacoemulsification instrument (CataRhex Swisstech, Oertli Instrumente AG, Switzerland). Insert the phacoemulsification needle into the balanced salt solution in the culture well plate, use ultrasonic energy of 20 - 40%, and ultrasonic time of 20 - 30 seconds. Then replace the balanced salt solution with the above four groups of culture media and place them in the incubator for continued culture. After 1 h and 24 h, observe and photograph the cell status under a microscope.

[0054] The results of protecting human corneal endothelial cells from damage and death caused by phacoemulsification treatment with different concentrations of nicotinamide are as Figure 2 shown: Treatment with different concentrations of nicotinamide can inhibit cell death caused by phacoemulsification and promote cell survival ( Figure 2 A). After 24 hours, statistical comparison of the cell density in different treatment groups found that the protective effect of nicotinamide on the number of corneal endothelial cells was concentration-dependent and gradually increased with the increase in concentration ( Figure 2 B).

[0055] Example 3: Establishment of an animal model of corneal endothelial cell injury caused by phacoemulsification for cataract

[0056] Experimental animals: New Zealand white rabbits (age, 1.5 years; weight, 5 - 7 kg, purchased from Jinan Xilingjiao Biological Co., Ltd.).

[0057] Phacoemulsification surgery: Use the AMO Signature phacoemulsification system (AMO, USA) to perform phacoemulsification and lens extraction on the right eye of each rabbit. The left eye serves as the normal eye. Make a 3.0 - mm clear corneal tunnel incision at the 11 - 12 o'clock position, and perform a continuous circular capsulorhexis in the center of the anterior lens capsule with a diameter of approximately 5.0 mm. Then, aspirate the lens contents, including the lens nucleus and residual lens cortex, using phacoemulsification. Set the ultrasonic energy to 25% and 30%, and the ultrasonic time to 4 minutes and 6 minutes respectively. After the operation, use a slit lamp to observe and record the changes in corneal transparency of New Zealand rabbits, and use optical coherence tomography (OCT) to analyze and measure the corneal thickness.

[0058] Results are as Figure 3 shown. With the increase in phacoemulsification intensity and prolongation of time, the degree of corneal turbidity and corneal thickness increase; when the cornea is treated with 25% energy, the cornea is edematous and turbid in the first 2 days after surgery; when treated with 30% energy for 4 minutes, the cornea remains edematous until it returns to normal on the 5th day after surgery; when treated with 30% energy for 6 minutes, corneal endothelial decompensation occurs, and the cornea remains edematous and turbid on the 11th day after surgery.

[0059] To better simulate the corneal change pattern in clinical patients after cataract surgery and screen effective drugs for protecting corneal endothelial cells, the condition of 30% energy for 4 minutes is selected for subsequent drug screening.

[0060] Example 4: Conduct animal experiments to verify the effective concentration of nicotinamide

[0061] Experimental grouping:

[0062] Control group: Compound electrolyte intraocular irrigation solution (Shike, Shenyang Xingqi Eye Medicine Co., Ltd.);

[0063] Experimental treatment groups: (1) Intraocular irrigation solution containing 2.5 mM nicotinamide; (2) Intraocular irrigation solution containing 5 mM nicotinamide. The preparation method is shown in Example 1.

[0064] Phacoemulsification surgery: According to the description in Example 3, perform phacoemulsification surgery on rabbits, aspirate the lens nucleus and residual lens cortex, set the ultrasonic energy to 30%, and the ultrasonic time to 4 minutes.

[0065] Results:

[0066] As Figure 4As shown, on the 2nd day after surgery, the corneas of rabbits in the experimental treatment group were all transparent, while those of the control group were edematous; moreover, the corneal thickness of the experimental treatment group was significantly lower than that of the control group.

[0067] As Figure 5 shown, the corneas of rabbits in the control group were edematous on the 1st day after surgery, with decreased transparency and increased corneal thickness. Within 5 days, the corneal transparency and thickness gradually returned to the normal state; however, in the experimental treatment group containing 2.5 mM nicotinamide, the corneas of rabbits were protected during the operation, and the corneal transparency and thickness were normal on the 1st day after surgery; on the 5th day after surgery, the corneas remained transparent and the thickness maintained the normal state.

[0068] As Figure 6 shown, the intraocular pressures of rabbits in the control group and the 2.5 mM nicotinamide experimental treatment group were measured. Comparative analysis found that: the nicotinamide irrigation fluid treatment group did not cause pathological increase in intraocular pressure within 7 days after surgery. Compared with the control group, the change trends of intraocular pressure in the two groups were the same, indicating that phacoemulsification cataract surgery would cause a transient increase in intraocular pressure, which basically returned to the baseline level after 3 days, and the increase in intraocular pressure did not exceed the normal range. At the same time, compared with the increased corneal thickness of the control group, the corneal thickness of rabbits in the experimental treatment group was lower than that of the control group on the 1st day after surgery, and the corneal thickness basically returned to the normal level after 3 days, and the recovery rate of its corneal thickness was better than that of the control group.

[0069] As Figure 7 shown, the morphology density of corneal endothelial cells treated with nicotinamide was detected on the 7th day after surgery. First, corneal endothelial confocal photography showed that, different from the enlarged cell volume and abnormal morphology of corneal endothelial cells in the control group, the endothelial cells in the nicotinamide treatment group were dense and regular in morphology ( Figure 7 A); the statistical analysis results of corneal endothelial cell density showed that the cell density in the nicotinamide treatment group increased significantly ( Figure 7 B); corneal tissue of the control group and the 2.5 mM nicotinamide experimental treatment group was collected for corneal endothelial cell spreading staining. The results showed that the barrier function protein ZO1 of corneal endothelial cells in the control group showed enlarged cells and increased atypia, and the expression and localization of the pump function protein ATP1A1 were disordered. However, the ZO1 staining of corneal endothelial cells in the 2.5 mM nicotinamide experimental treatment group showed regular cell morphology and normal expression and distribution of ATP1A1 ( Figure 7 C).

[0070] Example 5 Clinical Application Effectiveness Study

[0071] For cataract patients (humans, clinically diagnosed with cataract), phacoemulsification surgery was performed. During the operation, the experimental treatment group was irrigated with the NAM intraocular irrigation fluid containing 2.5 mM nicotinamide prepared according to the method of Example 1, and the compound electrolyte intraocular irrigation fluid was used as the control group.

[0072] The results are as Figure 8 shown. The corneas of the patients in the control group were edematous, with decreased transparency and increased corneal thickness on the first day after surgery. Within 7 days, the corneal transparency and thickness gradually returned to the normal state. However, for the patients in the experimental treatment group, their corneas were protected, with normal transparency and thickness on the first day after surgery. At 7 days after surgery, the corneas remained transparent and the thickness maintained the normal state. Meanwhile, by photographing the corneal endothelial cell density of both groups using a specular microscope, the results showed that the patients in the experimental treatment group better retained the corneal endothelial cell density, while the corneal endothelial cell density in the control group decreased significantly.

[0073] Based on the above results, the clinical application of the intraocular irrigation solution containing nicotinamide can reduce the corneal edema of cataract patients on the first day after surgery, decrease the reduction of corneal endothelial cell density, and lower the corneal endothelial cell loss rate.

[0074] Example 6 Comparison of the protective effects between nicotinamide irrigation solution and glutamine irrigation solution

[0075] It has been reported in the literature that glutamine (Gln) has a protective effect on corneal endothelial cells of mice under high intraocular pressure treatment. In this invention, 5 mM Gln was added to the irrigation solution as the control group (Gln group) and applied to the animal model of phacoemulsification surgery in rabbits; the NAM group used the intraocular irrigation solution containing 2.5 mM nicotinamide.

[0076] As Figure 9 shown, on the second day after surgery, the corneas of rabbits in the NAM group were transparent, while the corneas of rabbits in the Gln group were still edematous, and the corneal thickness in the NAM group was significantly lower than that in the Gln group. The results suggest that NAM has a specific protective effect on corneal endothelial cells when used in phacoemulsification surgery. Although it has been reported in the literature that Gln has a protective effect on corneal endothelial cells of mice during high intraocular pressure treatment, in terms of protecting corneal endothelial cells during phacoemulsification surgery, the protective effect of NAM is better than that of Gln treatment.

[0077] For the above specific embodiments, the present invention has been described in detail with general descriptions and specific implementation schemes. However, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. Use of nicotinamide in the preparation of an intraocular irrigation solution for protecting corneal endothelial cells during phacoemulsification surgery; The concentration of nicotinamide is 2.5 - 5 mM; The phacoemulsification surgery is performed on an individual with cataract; the individual is a human.

2. The application according to claim 1, characterized in that, Nicotinamide, as an active substance, has the effects of improving endothelial cell function, inhibiting cell apoptosis and cell fusion, and improving the condition of mitochondrial damage.

3. The application according to claim 1, wherein Protecting corneal endothelial cells includes alleviating or inhibiting the damage of corneal endothelial cells caused by ultrasonic stimulation, heat stimulation or oxidative stimulation, including corneal edema, reduction of corneal endothelial cells, abnormal corneal transparency, abnormal corneal thickness, abnormal corneal endothelial cell density, abnormal corneal endothelial cell morphology, and abnormal expression of corneal endothelial cell functional proteins.

4. The application according to claim 1, characterized in that, The cataract is senile cataract or diabetic cataract.

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