Cataract is a change in the transparency of the lens and is one of the major blinding eye diseases in China. Since medications have not yet been able to completely stop or reverse the lens clouding, cataract surgery is still the main treatment for this disease. Before performing cataract surgery, in addition to a comprehensive medical history of the patient, corresponding preoperative examinations and adequate preparation should be done.
Pre-operative examination
1.Ocular routine examination
①Check the patient’s eye appearance, near and far vision, corrected visual acuity, light perception and light localization, red-green vision, etc., and assess the patient’s preoperative visual acuity and other conditions;
② Slit lamp and ophthalmoscopy to record the degree of clouding of cornea, anterior chamber, iris and lens, and to examine the lens, vitreous, optic papilla, retina and macula after pupil dilatation to exclude active inflammation of the eye and to understand the fundus condition, etc.
2.Special eye examination
①Intraocular pressure and tear duct flushing to exclude glaucoma and dacryocystitis;
(2) Corneal curvature and A ultrasound to calculate the IOL and select a suitable IOL;
③ Corneal endothelial cell count, the endothelial cells of the cornea cannot be regenerated, and as age increases, the number gradually decreases and the area gradually increases, the normal value of corneal endothelial cell count is 3000~4000/mm2, if the corneal endothelial cell density decreases to below the critical level of 800 cells/mm2,
If the density of corneal endothelial cells decreases to below the critical level of 800 cells/square millimeter, the cornea will most likely suffer from edema or even large vesicular keratopathy due to the loss of endothelial cells after surgery due to the mechanical and chemical stimulation during cataract surgery;
④ Corneal topography to screen for corneal lesions such as cone corneas and to confirm the astigmatism of the cornea;
⑤ Ultrasound of the eye to observe the posterior segment (vitreous, retina, optic nerve, orbit);
(6) OCT examination to observe the fundus and clarify the macular morphology and structure.
3.Systemic examination
①Check the function of heart, lung, liver, kidney and other organs to ensure that they can tolerate the surgery, and if necessary, ask for internal medicine consultation;
②Try to maintain blood pressure below 150/90mmHg for hypertensive patients, fasting blood sugar below 8.0mmol/L for diabetic patients, and intraocular pressure below 21mmHg for patients with high intraocular pressure;
③ Coagulation function check, patients taking anticoagulant drugs should stop taking them for 3 days before surgery, and they can recover after surgery;
④Hepatitis B and syphilis examination to exclude infectious diseases.
4.Vision prediction after cataract surgery
Vision loss is the main reason for cataract patients to seek medical treatment, so it is very important to make postoperative vision prediction before cataract surgery. Since the cloudy lens obscures the direct observation of the retina, those who are in a position to do so can have laser interferometry and other examinations, which are of some significance in determining the efficacy of cataract surgery.
5.Special condition examination
①Patients with combined dry eyes: dry eye test, tear secretion test, corneal fluorescence staining, etc;
②Patients with combined glaucoma need to perform: UBM (check the cross-sectional condition of the front 1/5 of the eye and observe the atrial angle), computerized visual field (check the visual field defect), etc.
II Preoperative preparation
Routine preparation.
1. In general, the eye is spotted with antibiotic eye drops three days before surgery. The day before surgery, the bedside physician should communicate well with the patient and his family to make them understand the purpose of the surgery and the possible results of the surgery, and sign the surgery consent form after they fully understand. Patients should have good personal hygiene. On the day of surgery, please wash your face well and do not use any cosmetics. The patient’s preoperative preparation time is about half an hour. Eat easily digestible food on the day of surgery, and be accompanied by a family member.
2. Rinse the conjunctival sac and tear duct before surgery;
3.Start dilating the pupil 1 hour before surgery, once every 5 minutes or so, for a total of 3-5 times;
4.After being sent to the operating room, prepare for the disinfection and towel laying of the operating field;
5.About 10 minutes before the operation, start to use surface anesthetic drugs.
Preparation for special cases
1. For children with congenital cataract surgery.
1. Compared with adult patients, more attention should be paid to communication with their families and guardians so that they fully understand the purpose of surgery and the possible results of surgery, and sign the surgery consent form after they fully understand;
2, for children with general anesthesia, preoperative fasting should be routine: infants should fast 4 hours before surgery, and children over 2 years old should fast 6-8 hours before surgery. And an adequate amount of anticholinergic drugs should be used before surgery.
2. For cataract patients with complicated cases.
1.Before surgery, the doctor communicates fully with the patient and his family to let them understand the current condition, treatment methods, the purpose of surgery and possible situations during and after surgery, so that the patient can be prepared psychologically to eliminate tension and better cooperate with the surgery.
2.Preoperatively, according to the actual condition of the patient, selectively apply IOP-lowering drugs, anti-inflammatory drugs, antibiotics, sedatives, laxatives and other internal medicine.