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.
I. 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. to assess the patient’s preoperative visual acuity and other conditions.
② Slit lamp and ophthalmoscopic examination to record the degree of clouding of the 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 condition of the fundus, etc.
2.Special eye examination
①IOP, tear duct flushing to rule out glaucoma, dacryocystitis and other diseases.
② Corneal curvature, ocular A ultrasound, calculation of IOL prescription and selection of suitable IOL.
③ Corneal endothelial cell count, the endothelial cells of the cornea cannot be regenerated, and with age, the number gradually decreases and the area gradually increases. the cornea will most likely develop edema or even large vesicular keratopathy after surgery due to endothelial cell loss.
④ corneal topography to screen for corneal lesions such as cone corneas and to confirm the astigmatism of the cornea
⑤ ocular ultrasound to observe the posterior segment (vitreous, retina, optic nerve, orbit).
⑥OCT examination to observe the fundus, clarify macular morphology and structure.
3.Systemic examination
(i) Functional examination of the heart, lungs, liver, kidneys and other organs to ensure that the surgery can be tolerated, and if necessary, request consultation with internal medicine.
②For hypertensive patients, try to maintain blood pressure below 150/90mmHg, for diabetic patients, try to maintain fasting blood sugar below 8.0mmol/L, for patients with high intraocular pressure, try to maintain intraocular pressure below 21mmHg.
③ Coagulation function check, patients taking anticoagulant drugs should preferably stop taking them for 3 days before surgery, and they can recover after surgery.
④ Hepatitis 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 attention, 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 do laser interferometry and other examinations, which are of some significance in judging the efficacy of cataract surgery.
5.Special condition examination
①Patients with combined dry eyes, etc.: 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
(i) Routine preparation.
1. In general, the eyes should be spotted with antibiotic eye drops three days before surgery. The day before surgery, the bedside physician should communicate 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.Rinsing 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 of the operating field such as spreading of towels.
5.About 10 minutes before the operation, start to use surface anesthetic drug drops.
(ii) Preparation for special cases.
1. For children with congenital cataract surgery.
(i) Compared with adult patients, more attention should be paid to communication with their families and guardians so that they fully understand the purpose of the operation and the possible results of the operation, and sign the operation consent form after they fully understand.
②For 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. 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 method, 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, selectively apply IOP-lowering drugs, anti-inflammatory drugs, antibiotics, sedatives, laxatives and other internal medicine according to the actual condition of the patient.